WO2020261605A1

WO2020261605A1 - Washer fastening structure

Info

Publication number: WO2020261605A1
Application number: PCT/JP2019/049481
Authority: WO
Inventors: 松尾　誠; 興明林田; 喜直岩本
Original assignee: 株式会社松尾工業所; 株式会社iMott
Priority date: 2019-06-25
Filing date: 2019-12-17
Publication date: 2020-12-30
Also published as: JPWO2020261605A1; CN114008335A; CN114008335B; JP7128500B2

Abstract

The present invention optimizes a washer and a washer fastening structure such that a force is mostly oriented toward the opening side of a nut by guiding the position of the force applied onto the nut toward the outer circumferential side of a nut bearing surface and, consequently, reduces a load on the first thread where the bolt and nut are fastened and become engaged. A washer according to the present invention has a washer body and a bolt hole that passes through the washer body, the washer having, in the vertical cross-section thereof, a stress non-transmitting space that opens toward the bolt hole and that extends in the radial direction of the bolt hole, and the stress non-transmitting space having a concentric annular shape centered on the axis of the bolt hole.

Description

Washer fastening structure

The present invention relates to an improvement of a washer used in a properly tightened bolt / nut fastener, and reduces the load sharing ratio of the first mesh thread that maximizes the thread load sharing ratio of the bolt. It relates to a washer and a manufacturing method thereof for improving the breaking strength of fatigue cracks from the bottom of the valley. The improvement of the washer of the present invention not only reduces the load sharing rate of the first thread of meshing of the bolt, but also has an effect of leveling the load sharing rate of each thread, and the fatigue breaking strength from the threaded portion of the bolt. Can be enhanced.

Bolts, nuts and washers are used to fasten various structures. It is used in all kinds of equipment such as automobiles, ships, construction, railroad vehicles, civil engineering machines, and various machine tools. Fatigue fracture starting from the bottom of the bolt thread valley (Fig. 4, * part of the bolt) at the first meshing thread is often a problem with this fastening member, and efforts have been focused on improving the strength of the bolt as a countermeasure against fatigue fracture. Excessive load due to the static fastening force and external force of the first meshing thread is known, but the structure of the washer was examined for the purpose of improving the fatigue strength of the bottom of the bolt screw valley of the first meshing thread. It hasn't been done.

FIG. 1 is a vertical cross-sectional view showing fastening of objects to be fastened with conventional bolts, nuts, and washers. 1 is a washer, 2 is an object to be fastened, 3 is a bolt, 4 is a nut, 5 is a base, 4o is the open side of the nut thread (the direction of the arrow is the direction in which the screw is loosened), and 4c is the fastening side of the nut thread ( The direction of the arrow indicates the direction in which the screw is tightened).

Regarding the conventional fastening of bolts, nuts and washers, the numerical value of the load sharing ratio for flange nuts with 7 threads verified by the present inventor by finite element analysis (FEM analysis) is 35.6% for the first thread. The 2nd mountain is 20.8%, the 3rd mountain is 14.4%, the 4th mountain is 11.0%, the 5th mountain is 8.6%, the 6th mountain is 5.9%, and the 7th mountain is 3 It was also confirmed that the load sharing decreased sharply toward the open side of the screw thread at 9.9% (see FIGS. 4 and 9), which is consistent with many reports.

There are standards such as JIS and ISO for washers, and the main regulations are size (dimensions), hardness, parallelism, and geometric tolerance. Regarding the shape, the ring has a rectangular cross section, and part of the outermost surface is chamfered diagonally. There are only some that have been made (Non-Patent Document 1).

Regarding the structure and shape of the conventional washer, it is about "no harmful burrs", and the instructions for chamfering and deburring are unclear for those actually made by press working. As described above, the conventional washer has not been expected to have a function of improving the flow of force entering the nut or bolt in the required function. There was only a demand for functions such as the nut bearing surface not sinking into the object to be fastened and the surface texture of the object to be fastened not affecting the rotation of the nut.

Patent Document 1 discloses a set of high-strength bolts, nuts, and washers that reduce stress concentration generated at the bottom of the thread at the meshing end and have excellent delay fracture resistance and fatigue resistance. A protruding portion is provided on the center side of the diameter of the nut, and the washer has a height so that the protruding portion does not come into contact with the object to be fastened at a steady state. An example of a straight notch is shown for the central corner in contact with the nut of the washer. However, Patent Document 1 is characterized by a special nut having a protruding portion on the center side of the diameter, and the washer is a set part that complements the special nut, and the washer alone is not useful. The inner peripheral surface of the washer of Patent Document 1 does not align (center) the shaft of the bolt.

Japanese Unexamined Patent Publication No. 2003-4016

In the case of a conventional washer, the force flow on the nut side is most concentrated on the first thread for meshing with respect to the force in the bolt axial direction (initial tightening axial force: average stress, axial external force: fluctuating stress). It shows a non-uniform force flow characteristic that drops sharply after the second thread. In the case of the washer of the present invention, the force flow between the object to be fastened, the washer, and the nut is arranged as wide as possible on the outer peripheral side of the nut so that the force flow is widely distributed on each meshing thread and the first meshing screw. It has the effect of reducing the load concentration on the mountain. It provides a washer fastening structure that realizes this effect.

In the present invention, the washer fastening structure is optimized, and the inflow position of the force entering the nut is guided to the outer peripheral side of the nut bearing surface, so that a large amount of force is directed to the open side of the nut, and as a result, the bolt and the nut are fastened and meshed. It relates to the object of reducing the load on the first mountain, and the following aspects of the invention are provided.

(Aspect 1)
A bolt (3) extending from the object to be fastened (2) is inserted into a bolt hole (1h) of the object to be fastened (2) and a washer (1), and the washer (1) is inserted into the bolt (3) and the nut (4). ) Is used to fasten the object to be fastened (2) to the substrate (5) with a washer fastening structure.
The bolt (3), the washer (1), the nut (4), and the washer fastening structure have a common axis and axis direction (hereinafter, also simply referred to as "the axis" and "the axis direction") and the axis. Has a radial direction perpendicular to (hereinafter, also simply referred to as "the radial direction").
The washer (1) has a washer body (1b) and a bolt hole (1h) penetrating the washer body (1b).
The washer body (1b) has a stress non-transmission space (1s) that is a concentric annular shape centered on the axis of the bolt hole (1h).
The washer fastening structure, wherein the stress non-transmission space (1s) is open to the bolt hole (1h).

(Aspect 2)
In the radial direction, the side closer to the axis is the inside, and the side far from the axis is the outside.
The direction from the object to be fastened (2) to the washer (1) and from the washer (1) to the nut (4) is upward, upward or upward, and the opposite direction is downward, downward or downward.
The nut (4) has a flat lower plane (4w) extending in the radial direction and a screw extending in the axial direction, and the screw is alternately composed of threads and threads, and is a screw. Has a pitch p and
The stress non-transmission space (1s) of the washer body (1b) is formed from the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in a vertical cross section including the axis of the washer (1). The distance Ls in the radial direction from the position Ps to the extension line (4e) of the line connecting the screw valley bottoms of the nut (4) is the said distance Ls of the nut (4), where Ps is the position farthest to the outside in the radial direction. The washer fastening structure according to aspect 1, which has a length range of more than 0.5 times and 6 times or less the screw pitch p.

(Aspect 3)
The washer body (1b) has a flat upper plane (1u) extending in the radial direction on the nut (4) side and a flat lower surface (1u) extending in the radial direction on the object to be fastened (2) side. It has a flat surface (1w) and a bolt hole inner peripheral surface (1i) parallel to the axis line defining the bolt hole (1h).
The washer (1) has a thickness (T) from the upper plane (1u) to the lower plane (1w).
The stress non-transmission space (1s) is a first stress non-transmission space (11s) that opens in the bolt hole (1h) and also in the upper plane (1u) of the washer body (1b).
The first stress non-transmission space (11s) is formed in a vertical cross section including the axis of the washer (1).
The extension line of the upper plane (1u) of the washer body (1b) is defined as the first boundary line (B1), and the extension line of the inner peripheral surface of the bolt hole (1i) is defined as the second boundary line (B2). Position Pt below the one boundary line (B1) and outside the second boundary line (B2) in the radial direction and above the first boundary line (B1) and the position of the second boundary line (B2). It is a space where the line connecting Ph is the third boundary line (B3).
The position where the first boundary line (B1) intersects the second boundary line (B2) is Po, and the distance Lh in the axial direction from the position Ph to the position Ph is the screw of the nut (4). It is in the range of 0.01 times or more of the pitch p to 99% or less of the thickness (T) of the washer (1).
The first stress non-transmission space (11s) is a space surrounded by the first boundary line (B1), the second boundary line (B2), and the third boundary line (B3) in the vertical cross section. A concentric annular three-dimensional space formed by rotating the washer (1) around the axis.
(Hereinafter, the washer fastening structure having the first stress non-transmission space (11s) is referred to as "aspect A".)
The washer fastening structure according to the second aspect. The drawings of this aspect A correspond to FIGS. 5 to 12.

(Aspect 4)
In the aspect A, in the vertical cross section, the third boundary line (B3) of the first stress non-transmission space (11s) is at least deep in the axial direction from the first boundary line (B1). The washer fastening according to the third aspect, wherein the region up to 0.1 times the screw pitch p is composed of a curved line or a combination of a curved line and a straight line, has no corners, and is a stress concentration relaxation line. Construction.

(Aspect 5)
In the aspect A, in the vertical cross section, the third boundary line (B3) of the first stress non-transmission space (11s) is a fastening force applied to the upper plane (1u) of the washer body (1b). Is applied to the washer (1) assuming that the upper plane (1u) of the washer (1) is flat from the position Pt to the position Po, and is generated in the washer of the assumption. In the stress distribution equivalent to Mieses, the bolt hole is more than the stress distribution line on the bolt hole (1h) side where the relative stress is 95% based on the magnitude of the stress equivalent to Mieses applied vertically downward from the position Pt. The washer fastening structure according to

aspect

3 or 4, which is on the (1h) side.

(Aspect 6)
The washer body (1b) has a flat upper plane (1u) extending in the radial direction on the nut (4) side and a flat lower surface (1u) extending in the radial direction on the object to be fastened (2) side. It has a flat surface (1w) and a bolt hole inner peripheral surface (1i) parallel to the axis line defining the bolt hole (1h).
The washer (1) has a thickness (T) from the upper plane (1u) to the lower plane (1w).
The stress non-transmission space (1s) of the washer body (1b) is a second stress non-transmission space (12s) that does not open in the upper plane (1u) of the washer body (1b).
The second stress non-transmission space (12s) is radially outside from the position P1 of the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section including the axis of the washer (1). The line extending to the position Ph of the inner peripheral surface (1i) of the bolt hole or reaching the position P3 of the lower plane (1w) of the washer body (1b) is defined as the fourth boundary line (B4), and the bolt. A space in which the extension line of the inner peripheral surface (1i) of the hole is the fifth boundary line (B5), or optionally, the extension line of the lower plane (1w) of the washer body (1b) is the sixth boundary line (B6). And
The minimum thickness (Th) of the eaves, which is the shortest dimension in the axial direction from the upper plane (1u) of the washer body (1b) to the second stress non-transmission space (12s), is the thickness of the washer 1. 1% or more of T,
The second stress non-transmission space (12s) is the fourth boundary line (B4) and the fifth boundary line (B5), or the fourth boundary line (B4) and the fifth boundary line (B4) in the vertical cross section. A concentric annular three-dimensional space formed by rotating the space surrounded by B5) and the sixth boundary line (B6) around the axis of the washer (1).
(Hereinafter, the washer fastening structure having the second stress non-transmission space (12s) is referred to as "aspect B").
The washer fastening structure according to the second aspect.

(Aspect 7)
In the aspect B, in the vertical cross section, the second stress non-transmission space (12s) is also opened on the lower plane (1w) side of the washer body (1b), and the fourth boundary line (B4). ) Extends upward from the lower plane (1w) of the washer body (1b) at an angle within 20 degrees with respect to the axis direction, and is in contact with a straight line forming an elevation angle of 20 to 25 degrees with respect to the axis. A corner portion (Bc) connecting the rising portion (Br) leading to the position and a position in contact with two straight lines forming elevation angles of 20 to 25 degrees and 65 to 70 degrees with respect to the axis, and the corner portion (Bc) connecting the corner portion to the above. The washer fastening structure according to aspect 6, which includes a bolt hole inner peripheral end portion (Be) leading to the bolt hole inner peripheral surface (1i).

(Aspect 8)
In the aspect B, in the vertical cross section, the fourth boundary line (B4) is a connection point of the washer body (1b) with the lower plane (1w) and / or the inner peripheral surface of the bolt hole (1i). The washer fastening structure according to

aspect

6 or 7, wherein the stress concentration relaxation line is composed of a curved line or a straight line with a curved line and has no corners.

(Aspect 9)
In the plan view of the fastening structure viewed from the axial direction, the contact surface between the upper plane (1u) of the washer (1) and the lower plane (4w) of the nut (4) is centered on the axis. Assuming a circle inscribed in the contact surface, the radius of the inscribed circle is the radial distance between the line (4e) connecting the valley bottoms of the screws of the nut (4) and the axis of the nut. The washer fastening structure according to any one of aspects 3 to 8, which has a dimension of at least 0.8 times the sum of 2 times the distance Ls and the distance Ls.

(Aspect 10)
The washer fastening structure according to any one of aspects 2 to 9, wherein the distance Ls is in the range of a length of 2 times or more and 4 times or less of the screw pitch p.

(Aspect 11)
The washer fastening structure according to any one of aspects 1 to 10, wherein the nut (4) is a flange nut.

(Aspect 12)
A washer body (1b) having parallel first and second planes (1u, 1w) and a washer body (1b) penetrating and extending in a direction perpendicular to the first and second planes (1u, 1w). A washer (1) having a bolt hole (1h) to be formed, wherein the washer (1) has an axis of the bolt hole (1h) and a radial direction perpendicular to the axis.
The washer body (1b) has a stress non-transmission space (1s) that opens into the bolt hole (1h) and extends in the radial direction in a vertical cross section including the axis of the washer (1).
A washer characterized in that the stress non-transmission space (1s) is a concentric annular shape centered on the axis of the bolt hole (1h).

(Aspect 13)
The stress non-transmission space (1s) of the washer body (1b) is in the radial direction from the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section of the washer (1). Let Ps be the position of the stress non-transmission space (1s) farthest to the outside, and the distance L in the radial direction from the position Ps to the inner peripheral surface parallel to the axis of the bolt hole (1h) or an extension line thereof. But,
0.5p ≤ L ≤ 5.7p
(In the formula, the diameter of the bolt hole (1h) is R, and the units of R and p are mm.
When R is 1.9 or less, p is 0.2 and
When R is more than 1.9 and less than 2.4, p is 0.25.
When R is more than 2.4 and 3.7 or less, p is 0.35.
When R is more than 3.7 and 5.5 or less, p is 0.5.
When R is more than 5.5 and 7.5 or less, p is 0.75.
When R is more than 7.5 and 9.5 or less, p is 1.0.
When R is more than 9.5 and 13 or less, p is 1.25.
When R is more than 13 and 23 or less, p is 1.5.
When R is more than 23 and less than 34, p is 2.
When R is more than 34 and less than 40, p is 3.
When R is more than 40 and 150 or less, p is 4. )
The washer according to aspect 12, which satisfies the above conditions.

(Aspect 14)
The direction from the second plane (1w) of the washer body (1b) toward the first plane (1u) is defined as an upward, upward or upward direction, and the opposite direction is defined as a downward, downward or downward direction.
In the vertical cross section of the washer (1), the stress non-transmission space (1s) is a first stress non-transmission space (11s) that also opens to the first plane (1u) of the washer body (1b). ,
The washer body (1b) extends below the first stress non-transmission space (11s) to an inner peripheral surface of the bolt hole (1h) parallel to the axis.
(Hereinafter, the washer fastening structure having the first stress non-transmission space (11s) is referred to as "aspect A".)
The washer according to aspect 12 or 13.

(Aspect 15)
In the washer (1) of the aspect A, in the vertical cross section, the third boundary line (B3) between the washer body (1b) and the first stress non-transmission space (11s) is the first plane. From (1u), at least in the region from the depth in the axial direction to 0.1 times the p, the stress concentration relaxation line is composed of a curved line or a combination of a curved line and a straight line, and has no corners. A washer according to aspect 14.

(Aspect 16)
The washer (1) of the aspect A, in the vertical cross section of the washer (1).
The boundary line (B3) between the washer body (1b) and the first stress non-transmission space (11s) has a shape in which the washer body (1b) does not have the first stress non-transmission space (11s). In the stress distribution corresponding to Mieses formed on the washer body (1b) when a fastening force is applied to the upper plane (1u) of the washer body (1b), the upper plane (1u) is assumed to be. Is 95% of the stress value equivalent to Mieses, which is 95% of the stress value equivalent to Mieses applied in the downward direction perpendicular to the upper plane (1u) from the position where is in contact with the first stress non-transmission space (11s). It is on the bolt hole (1h) side of the distribution curve and
The third boundary line (B3) between the washer body (1b) and the first stress non-transmission space (11s) is a curved line or a straight line with a curved line, and is a stress concentration relaxation line having no corners. , The washer according to aspect 14 or 15.

(Aspect 17)
In the vertical cross section of the washer (1), the first plane (1u) of the washer body (1b) extends to the inner peripheral surface (1i) of the bolt hole parallel to the axis of the bolt hole (1h). The washer body (1b) forms an eaves portion (1p) on the upper side of the first plane (1u), and the stress non-transmission space (1s) is formed on the lower side of the eaves portion (1p). The existing second stress non-transmission space (12s),
(Hereinafter, the washer fastening structure having the second stress non-transmission space (12s) is referred to as "aspect B").
The washer according to aspect 12 or 13.

(Aspect 18)
In the washer (1) of the aspect B, in the vertical cross section of the washer (1), the second stress non-transmission space (12s) is on the second plane (1w) side of the washer body (1b). The boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is in the axial direction from the second plane (1w) of the washer body (1b). The rising portion (Br) that extends upward at an angle within 20 degrees to reach a position where it comes into contact with a straight line forming an elevation angle of 25 degrees with respect to the axis, and elevation angles of 20 to 25 degrees and 65 with respect to the axis. Aspect 17 includes a corner portion (Bc) connecting a straight line forming about 70 degrees and a position in contact with each other, and a bolt hole inner peripheral end portion (Be) extending from the corner portion to the bolt hole inner peripheral surface (1i). Described washer.

(Aspect 19)
The fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) in the vertical cross section of the washer (1) of the aspect B. ) Is a curved line or a straight line with a curved line and has no corners, and is a stress concentration relaxation line. However, the connection portion with the second plane (1w) does not have to be a stress concentration relaxation line. Or the washer according to 18.

(Aspect 20)
The washer according to any one of aspects 13 to 19, satisfying 2p ≦ L ≦ 4p.

(Aspect 21)
In the plan view of the washer (1) viewed from a direction perpendicular to the axis, the diameter of the circle inscribed in the outer circumference of the upper plane (1u) of the washer body (1b) is D, and the diameter of the circle of the bolt hole (1h) is defined as D. Described in any one of aspects 13 to 20, wherein the diameter is R, and (D / 2) ^2- (R / 2 + L) ² ≧ k (R / 2) ² (k = 2.5 in the formula). Washer.

(Aspect 22)
Aspect 12 in which a part or all of the surface of the washer (1) is subjected to surface treatment for the purpose of rust prevention, abrasion resistance, lubricity improvement, slidability improvement, appearance improvement, decoration, or identification. The washer according to any one of 21 to 21.

(Aspect 23)
22. Aspect 22 in which the surface treatment is plating, plasma CVD coating, plasma PVD coating, vacuum deposition, resin coating, polymer coating, alumite, or manganese phosphate chemical conversion treatment, or a combination of two or more thereof. Washer.

(Aspect 24)
The washer according to any one of aspects 12 to 23, wherein the material of the washer (1) is selected from a metal, a nitride, a carbide, an oxide, or a hard resin (including CFRP).

(Aspect 25)
The washer according to any one of aspects 12 to 24, wherein the two planes of the washer (1) have a surface roughness of 50 μm or less and a flatness of 0.2 mm or less in arithmetic average roughness Ra.

(Aspect 26)
Aspects 12 to 25 characterized in that the washer (1) is processed and manufactured by pressing, cutting, grinding, cold, warm, hot pressing, casting, forging, or a combination of these methods. The method for manufacturing a washer according to any one of the items.

(Aspect 27)
The method for manufacturing a washer according to aspect 26, wherein molding is performed using a mold, a cutting tool, a cutting tool, or a combination thereof.

When the washer fastening structure of the present invention is used, the load sharing ratio of the first thread of fastening mesh of bolts and nuts can be reduced, for example, from 35.6% of the conventional structure to around 30%. Due to this effect, the stress of the total actual load, which is repeatedly input in the direction of the initial fastening axial force, is also reduced at the same rate, so that the fatigue strength of the bolt thread valley bottom of the first meshing thread is improved. It has the effect of improving the safety and durability of the fastening structure.

For the processing and manufacturing of the washer of the present invention, conventionally used machines, processing jigs, processing tools, press processing machines, cold, warm, hot forging machines, casting equipment, etc. can be used. In press working (an example of plastic working), only the shape of the plastic working die changes.

In addition, among the construction methods and processing tools for processing this washer, special cutting tools are rational, which leads to realization of reduced man-hours and prevention of processing errors. The plastic working die (pressing die, etc.) is the same as the dedicated tool, and since the space structure machining portion is inserted in the die, the fatigue strength improving effect of the bolt of the present invention can be obtained without increasing the man-hours. Similarly, in forging, casting, etc., by incorporating this technology into the die, it is possible to obtain the effect of improving the fatigue strength of the first mountain valley bottom of bolt fastening.

In the present disclosure, it is described that the washer fastening structure of the present invention mainly improves the fatigue strength of a bolt screw, but it is known that a nut screw also deteriorates due to the same cause and mechanism as a bolt screw. Although the fatigue failure of bolts is less than that of bolts, the washer of the present invention is also effective in improving the fatigue strength of nut screws.

FIG. 1 is a vertical cross-sectional view showing an example of a fastening structure using a conventional washer. FIG. 2 is a diagram showing a flow of tensile stress applied to a bolt in the fastening structure of FIG. FIG. 3 is a diagram showing the flow of compressive stress applied to the nut in the fastening structure of FIG. FIG. 4 is a diagram showing a Mises equivalent stress distribution in which the tensile stress of FIG. 2 and the compressive stress of FIG. 3 are combined. FIG. 5 is a vertical cross-sectional view showing an example of a fastening structure using a washer according to the aspect A of the present invention. FIG. 6 is a partially enlarged vertical sectional view of the washer fastening structure of FIG. 7 (a) is a vertical cross-sectional view of the washer of FIG. 5, and FIGS. 7 (b) and 7 (c) are perspective views of the washer of FIG. FIG. 8 is a diagram showing a Mises equivalent stress distribution in the example of the washer fastening structure of FIG. 9 (a) and 9 (b) are tables and graphs comparing the Mises equivalent stress distributions of FIGS. 4 and 8. FIG. 10 is a graph and a diagram showing a Mises equivalent stress distribution when the shape of the first stress non-transmission space is changed in the example of the washer of the aspect A. 11 (a) and 11 (b) are diagrams showing the Mises equivalent stress distribution and the shape of the first stress non-transmission space in the washer of the aspect A. 12 (a) to 12 (e) are vertical cross-sectional views showing a modified example of the washer according to the aspect A of the present invention. FIG. 13 is a vertical sectional view showing an example of a fastening structure using a washer according to the aspect B of the present invention. FIG. 14 is a partially enlarged vertical sectional view of the vertical sectional view of the washer of FIG. 15 (a) is a vertical cross-sectional view of the washer of FIG. 13, and FIGS. 15 (b) and 15 (c) are perspective views of the washer of FIG. FIG. 16 is a diagram showing a Mises equivalent stress distribution in the example of the washer fastening structure of FIG. 17 (a) and 17 (b) are tables and graphs comparing the Mises equivalent stress distributions of FIGS. 4 and 16. FIG. 18 is a graph and a diagram showing a Mises equivalent stress distribution when the shape of the second stress non-transmission space is changed in the example of the washer of the aspect B. 19 (a) to 19 (d) are vertical cross-sectional views showing a modified example of the washer according to the aspect B of the present invention. FIG. 20 is a vertical sectional view showing a modified example of the washer according to the aspect B of the present invention. 21 (a) to 21 (d) show an example of the shape of the cutting tool for manufacturing the washer of the present invention. FIG. 22 shows an example of a mold for manufacturing the washer of the present invention. FIG. 23 shows an example of a mold such as a mold for manufacturing the washer of the present invention.

[First aspect of the present invention]
In the first aspect, the present invention
A bolt (3) extending from the object to be fastened (2) is inserted into a bolt hole (1h) of the object to be fastened (2) and a washer (1), and the washer (1) is inserted through the bolt (3) and the nut (4). ) Is used to fasten the object to be fastened (2) to the base (5) (the base 5 may be the head (3h) of the bolt 3) with a washer fastening structure.
The bolt (3), the washer (1), the nut (4), and the washer fastening structure have a common axis and axis direction (hereinafter, also simply referred to as "the axis" and "the axis direction") and the axis. Has a radial direction perpendicular to (hereinafter, also simply referred to as "the radial direction").
The washer (1) has a washer body (1b) and a bolt hole (1h) penetrating the washer body (1b).
The washer body (1b) has a stress non-transmission space (1s) that is a concentric annular shape centered on the axis of the bolt hole (1h).
The stress non-transmission space (1s) provides a washer fastening structure characterized in that it is open to the bolt hole (1h).
The first aspect of the present invention will be described in detail below with reference to the drawings without any limitation.

FIG. 1 is a vertical cross-sectional view showing an example of a washer fastening structure in the prior art, and FIG. 5 is a vertical cross-sectional view showing an example of a washer fastening structure on the first side surface of the present invention. With reference to FIGS. 1 and 5, a bolt (3) extending from the substrate 5 side is inserted into a bolt hole (1h) of the object to be fastened (2) and a washer (1), and a washer (1) is interposed. The present invention relates to a washer fastening structure for fastening an object to be fastened (2) to a substrate (5) with bolts (3) and nuts (4). In the washer fastening structure on the first side surface of the present invention, the washer (1) exists between the nut (4) and the object to be fastened (2).

In FIGS. 1 and 5, the bolt (3) penetrates the substrate (5), the object to be fastened (2) and the washer (1) and is connected to the nut (4), whereas the bolt (3) is It may be a part of the substrate (5), or it may be embedded in the substrate (5) and does not penetrate the substrate (5). The bolt (3) has a columnar screw shaft body and a screw portion (male screw) that engages with a nut at the tip of the screw shaft body, and the screw portion has threads and threads, and between threads and threads. It has a pitch p, which is the distance between the valleys. The outer diameter of the bolt (3) is usually designated by the diameter of the thread top. In the axial direction of the bolt (3), the tip side having the threaded portion of the bolt (3) is called the (screw) opening side, and the opposite direction is called the (screw) fastening side. Correspondingly, the nut (4) also has an open side (4o) at which the screw of the nut is released and a fastening side (4c) at which the nut is fastened.

The nut (4) has a screw shaft portion (4s) and a female screw (thread portion) that penetrates the screw shaft portion (4s) and corresponds to the male screw of the bolt (3). The thread diameter of a nut is usually referred to by the diameter of the thread root. The cross section of the screw shaft portion (4s) is generally hexagonal, but it may be a polygon other than a hexagon. In the present invention, the nut (4) is not essential, but preferably has a flange portion (4f) on the washer (1) side of the screw shaft portion (4s). The flange portion (4f) refers to a portion having an outer peripheral dimension larger than the outer peripheral dimension of the screw shaft portion (4s). Here, the outer peripheral dimensions of the screw shaft portion (4s) and the flange portion (4f) may be the dimensions (diameter) of a circle inscribed in the screw shaft portion (4s) and the flange portion (4f) in the plan view. The thread of the nut (4) has threads and threads and has the same pitch p as the thread of the bolt (3), but the diameter of the thread root of the nut (4) is slightly smaller than the outer diameter of the bolt (3). Is set to a large value. Similarly, the diameter of the thread crest of the nut (4) is set slightly larger than the diameter of the thread crest bottom of the bolt (3). In the axial direction of the nut (4), the open side of the bolt (3) is called the open side (4o) of the nut (4), and the opposite direction is called the fastening side (4c).

In the present invention, the object to be fastened (2) and the substrate (5) are not particularly limited. If the object to be fastened and the substrate are fastened with bolts and nuts, the benefits of the washer fastening structure of the present invention can be enjoyed. Fastening with bolts and nuts is widely used in aircraft, automobiles, railroad vehicles, machine tools, civil engineering machines, agricultural machines, various manufacturing equipment, bridges, building structures, etc., and the washer fastening structure of the present invention is any of them. Is also applicable.

(Load sharing rate of fastening stress in screws)
When fastening the bolt (3) and the nut (4), the slope on the thread valley opening side of the nut (4) presses against the fastening side slope of the thread of the bolt (3), so that the bolt (3) A tensile stress is applied to the fastening side slope of the screw thread with the root of the bolt (3) (the bolt head (3h) in FIG. 1A), and this becomes the axial force. Further, when the nut (4) is pressed toward the fastening side, a compressive stress is applied between the slope of the nut (4) on the thread valley opening side and the object to be fastened (the seating surface of the nut (4)), and the bolt (3) The slope on the fastening side of the screw thread is pressed by the slope on the thread valley opening side of the nut (4), and compressive stress is applied. As a result, the screw of the bolt (3) is subjected to a stress obtained by combining the above tensile stress and compressive stress (vector synthesis). Since the tensile stress and the compressive stress have the property of bearing a larger stress closer to the bolt head (3h), the maximum stress is applied to the first thread of the fastening engagement of the bolt (3), and the second and third threads are applied. The stress load decreases toward the eyes and the open side. Hereinafter, in the present disclosure, the number of threads of a screw indicates the order of the threads counted from the first thread of fastening meshing. Since the screw is spiral in the axial direction, the position of the thread number of the screw is the position at the average value (median value).

FIG. 2 is a vector diagram showing the direction and magnitude of tensile stress applied to the bolt (3) when the bolt (3) and the nut (4) are fastened in a fastening body including a conventional washer by FEM analysis. The direction of the vector in the figure is the direction of stress, and the length and density of the vector represent the magnitude of stress. The tensile stress applied to the bolt (3) is maximum at the first thread of the fastening mesh and decreases toward the higher thread on the open side. Similarly, FIG. 3 shows FEM analysis of the direction and magnitude of the compressive tension applied to the nut (4) when the bolt (3) and the nut (4) are fastened in the fastening body including the conventional washer. It is a vector diagram to represent, the direction of the vector in the figure is the direction of stress, and the length and density of the vector represent the magnitude of stress. The reaction force of this compressive tension is applied to the slope on the fastening side of the thread of the bolt (3). FIG. 4 is a FEM analysis of the Mises equivalent stress applied when fastening the bolt (3) and the flange nut (4) having the shape shown in FIG. 4 in the fastening body including the conventional washer. It is a diagram that combines the tensile stress diagram, the compressive stress of FIG. 3, and its reaction force.

In FIG. 4, the region where the Mises equivalent stress is maximum is white, the region where it is minimum is black, and the middle is represented by two levels of light and dark gray (gray scale). In FIG. 4, the force (white area) applied from the innermost diameter of the washer concentrates on the first thread on the fastening side of the nut immediately above, and the first thread of this nut is filled with white and light gray. It works in the direction of pressing the fastening side surface of the first thread of the bolt, and presses against each other in white, and white and light gray are also generated inside the bolt. As shown in FIG. 4, an axial force is applied to the bolt downward (toward the bolt head direction), and the force is exchanged with the nut at the thread on the open side from the first mesh thread. The thread just below the first thread of the bolt screw (on the bolt head side) receives a lot of bolt axial force because there is no nut thread, and the first thread of the nut works to push up the first thread of the bolt screw. It is under great stress to open the part. Next, it is transmitted to the second thread, and there are small white and light gray around, but it is much smaller than the first thread, and dark gray has entered the nut thread. Next, the light gray on the 3rd thread appears small on the nut thread side, the 4th thread becomes almost dark gray, and the 5th thread has a lot of weak black stress, and the 6th and 7th threads. In the eyes, black with low stress is the most distributed. As shown in the load sharing ratio table, this stress distribution situation shows a non-uniform situation far from leveling. This * part is the bottom of the first bolt screw valley of the fastening mesh, and is a place where fatigue fracture often occurs. With reference to FIG. 4, it can be seen that the maximum stress is applied to the first thread from the fastening side of the bolt 3, and the stress load becomes smaller toward the second and third threads and the open side. As shown in FIG. 9, the numerical value of the load sharing ratio is 35.6% for the first mountain, 20.6% for the second mountain, 14.5% for the third mountain, and 11. It was 0%, the 5th mountain was 8.5%, the 6th mountain was 5.9%, and the 7th mountain was 3.9%.

Looking at the stress distribution generated in the washer (1) in FIG. 4, since the washer (1) and the nut (4) are in contact with each other on the entire seat surface, the black color with a small stress is on the outer peripheral side of the washer (1) and It spreads widely in the center and receives the compressive force from the nut (4) in a wide range, but a white with a large stress appears at the point where it is in contact with the nut (4) at the innermost diameter, and a light gray color. It has the same area as the first thread of the nut, and the dark gray area is greatly expanded. This indicates a situation in which a high Mises equivalent stress is propagated to the contact portion with the nut (4) directly above at the end of the washer (1) on the inner wall side of the bolt hole.

(Stress non-transmission space)
The washer fastening structure of the present invention aims to improve the durability of the bolt (3) and extend the fatigue life by reducing the stress load factor of the first thread of the fastening mesh of the bolt (3).

FIG. 6 is a partially enlarged view of the washer (1) near the bolt hole (1h) in which the washer (1) and the nut (4) of FIG. 5 are engaged. FIG. 7A is a vertical sectional view of the washer (1), and FIGS. 7B and 7C are perspective views seen from above and below the washer (1).

According to the first aspect of the present invention, referring to FIGS. 5 to 7, the washer (1) is a washer body (1b) having an upper plane (1u) and a lower plane (1w), and a washer body (1b). ) Has a bolt hole (1h) penetrating the upper plane (1u) and the lower plane (1w), and the washer body (1b) has a stress non-transmission space (1s). The upper plane (1u) of the washer body (1b) refers to the surface on the side that engages with the nut (4). In the following description, the side of the washer (1) that engages with the nut (4) is referred to as the upper, upper, and upper directions, and the side of the washer (1) that engages with the object (2) is referred to as the lower and lower sides. , Called downward.

In the first aspect of the present invention, the washer body (1b) has a stress non-transmission space (1s) that is concentric and annular around the axis of the bolt hole (1h), and the stress non-transmission space (1s) is It is open to the bolt hole (1h). The stress non-transmission space (1s) may be opened in the bolt hole (1h) and also in the upper plane (1u) of the washer body (1b) (for example, FIGS. 5 to 7), or the bolt hole (1h). It may be opened in the lower plane (1w) of the washer body (1b) as well as in the bolt hole (1h) (for example, FIGS. 13 to 15), or it may be opened in the bolt hole (1h) but in the upper plane (1b) of the washer body (1b). It does not have to be open in either 1u) or the lower plane (1w) (for example, FIG. 19C). FIGS. 5 to 7 show an example in which the stress non-transmission space (1s) is opened not only in the bolt hole (1h) but also in the upper plane (1u) of the washer body (1b). When the non-transmission space (1s) is also open to the upper plane (1u) of the washer body (1b), the stress non-transmission space (1s) is referred to as a first stress non-transmission space (11s) (Aspect A). The first stress non-transmission space (11s) is not open to the lower plane (1w) of the washer body (1b). On the other hand, as in the examples of FIGS. 13 to 15, when the stress non-transmission space (1s) is not opened in the upper plane (1u) of the washer body (1b), the stress non-transmission space (1s) is not second stressed. A transmission space (12s) (Aspect B). The second stress non-transmission space (12s) may or may not be open in the lower plane (1w) of the washer body (1b). In the following, if necessary, the first stress non-transmission space (11s) and the second stress non-transmission space (12s) are collectively referred to as a stress non-transmission space (1s).

In the aspect A, the first stress non-transmission space (11s) has an extension line of the upper plane (1u) of the washer body (1b) as the first boundary line (B1) in the vertical cross section including the axis of the washer (1). , The extension line of the inner peripheral surface (1i) of the bolt hole is the second boundary line (B2), which is below the first boundary line and radially outside the second boundary line, and is located at the position Pt of the first boundary line and the second. It is a space where the line connecting the position Ph of the boundary line is the third boundary line (B3), and the first boundary line (B1), the second boundary line (B2), and the third boundary line (B3) in the vertical cross section. It is a concentric annular three-dimensional space formed by rotating the space surrounded by the washer (1) around the axis of the washer (1). The position Pt where the third boundary line (B3) is in contact with the first boundary line (B1) is the position farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the first stress non-transmission space (11s). preferable. With reference to the preferred examples of FIGS. 5 to 7, the first stress non-transmission space (11s) is the boundary position Pt between the first stress non-transmission space (11s) and the upper plane (1u) of the washer body (1b). It has a boundary position Ph between the one stress non-transmission space (11s) and the inner peripheral surface of the bolt hole (1i) of the washer body (1b), and the nut (4) is located farthest in the radial direction from the inner peripheral surface of the bolt hole (1i). The distance from the extension line of the upper plane (1u) of the washer body (1b) to the position Ph has Ls as the distance to the extension line of the line connecting the screw valley bottoms of). In the first aspect of the present invention, the distance Ls is defined as the distance from the position farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole to the extension line of the line connecting the thread valley bottoms of the nut (4), and the first stress. The boundary position Pt between the non-transmission space (11s) and the upper plane (1u) of the washer body (1b) is the position Ps farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the first stress non-transmission space (11s). It is preferable to have (for example, FIGS. 5 to 7). However, the position Ps farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the first stress non-transmission space (11s) is the upper plane (1u) of the first stress non-transmission space (11s) and the washer body (1b). It may be in the middle of the third boundary line (B3) connecting the position Pt and the position Ph instead of the boundary position Pt with the position Pt.

In aspect B, the second stress non-transmission space (12s) extends radially outward from the position P1 of the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section including the axis of the washer (1). At present, it reaches the position P2 of the inner peripheral surface (1i) of the bolt hole (see, for example, FIG. 19 (c)) or reaches the position P3 of the lower plane (1w) of the washer body (1b) (see, for example, FIGS. 13 to 15). )) The line is the fourth boundary line (B4), the extension line of the inner peripheral surface of the bolt hole (1i) is the fifth boundary line (B5), or additionally the lower plane (1w) of the washer body (1b) is extended. It is a space where the line is the sixth boundary line (B6), and the fourth boundary line (B4) and the fifth boundary line (B5) or the fourth boundary line (B4) and the fifth boundary line (B5) in the vertical cross section. ) And the sixth boundary line (B6), which is a concentric annular three-dimensional space formed by rotating the space around the axis of the washer (1). Referring to FIGS. 13 to 15, even in the second stress non-transmission space (12s), the position farthest from the bolt hole (1h) is set as Ps, and the position Ps is extended to the extension line of the line connecting the screw valley bottom of the nut (4). Has Ls as the distance of. In the examples of FIGS. 13 to 15, the position P3 on the lower plane (1w) is the position Ps farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the second stress non-transmission space (12s).

In the vertical section of the washer (1), the washer body (1b) extends to the bolt hole 1h below and / or above the stress non-transmission space (1s), and the tip of the extending portion extends the bolt hole. The inner peripheral surface (1i) of the bolt hole to be defined is formed. The inner peripheral surface (1i) of the bolt hole should have a line segment parallel to the axis in the vertical cross section, but may be a point as the ultimate case of the line segment. The extending portion of the washer body (1b) forming the inner peripheral surface (1i) of the bolt hole is for aligning the bolt (3) and the washer (1), and is at least two places, preferably at least three, in the plan view. At the location, it is necessary to extend to the inner peripheral surface (Ii) of the bolt hole, but the portion extending to the inner peripheral surface (1i) of the bolt hole may be convex, that is, in the plan view. A space may be formed in a region other than the protrusion (not shown). Such a space is a region where the washer body 1b below the stress non-transmission space (1s) exists in the vertical cross-sectional views of FIGS. 5 to 7, and the stress in the vertical cross-sectional views of FIGS. 13 to 15. This is the region where the washer body (1b) above the non-transmission space (1s) exists. Such a space does not need to be formed, but when it is formed, it forms a space continuous with the stress non-transmission space (1s). However, this space is different from the stress non-transmission space (1s) defined by the present invention.

In the washer fastening structure on the first side surface of the present invention, since the washer (1) has a stress non-transmission space (1s), when fastening the bolt (3) and the nut (4), the nut (4) and the washer (1s) are fastened. In the compressive stress applied to and from 1), the stress cannot be transmitted in the region on the bolt hole (1h) side of the washer body (1b) where the stress non-transmission space (1s) exists. The compressive stress at the time of fastening basically acts at an angle slightly inclined from the outside to the inside in the axial direction or the radial direction of the bolt holes (1h) of the nut (4) and the washer body (1b) (that is, basically). In addition, it acts in the axial direction and in the vertical direction of FIG. 6). Therefore, in the vertical section of the washer (1), in the region where the stress non-transmission space (1s) exists, the compressive stress is not transmitted in the vertical direction or the horizontal direction, so that the stress non-transmission space (1s) of the washer (1) is not transmitted. ) The vertical compressive stress in the outer region in the radial direction bends inward in the radial direction above the stress non-transmission space (1s), so that the screws of the bolt (3) and nut (4), especially the lower order. Can act on threaded threads. The maximum angle at which the compressive stress in the vertical direction can be bent is about 45 degrees. Therefore, the larger the radial dimension of the stress non-transmission space (1s) on the bolt hole side at the boundary between the washer (1) and the nut (4), the more the compression acting on the screws of the bolt (3) and the nut (4). The stress moves to the higher-order side threads, and the stress on the lower-order threads, especially the first thread, becomes smaller. Thus, in the washer fastening structure on the first side surface of the present invention, the stress non-transmission space (1s) as described above is formed in the washer (1) to lower the order of the bolt (3) and the nut (4). The stress load sharing ratio of the threads of the threads, especially the threads of the first thread, can be reduced, and the fatigue strength of the valley bottom of the first thread where the bolt (3) is engaged can be improved.

FIG. 8 shows an example of the washer fastening structure on the first side surface as shown in FIGS. 5 to 7, with the same dimensional configuration as the conventional method of FIG. 4, and the radial dimension of the stress non-transmission space (1s), that is, The boundary between the upper plane (1u) of the washer (1) and the stress non-transmission space (11s) at the position farthest from the bolt hole (1h) of the stress non-transmission space (1s) in the upper plane (1u) of the washer (1). The distance Ls from the position Pt to the extension line (4e) of the line connecting the thread valley bottom of the nut (4) is set to about 2.21p (corresponding to 2.21 pitch), and the axial dimension of the stress non-transmission space (11s). (Depth), that is, the deepest in the inner peripheral surface (1i) of the bolt hole of the stress non-transmission space (11s) from the position Po of the upper plane (1u) of the washer (1) in the extension line of the inner peripheral surface (1i) of the bolt hole. Bolt (3) and nut (4) with the distance Lh to the boundary position Ph between the inner peripheral surface of the bolt hole (1i) and the stress non-transmission space (11s) being about 1.0p (equivalent to 1.0 pitch). It is a figure which FEM-analyzed the stress equivalent to Mieses applied at the time of fastening, and it becomes the figure corresponding to FIG. 4. It should be noted that the other part except the shape and dimension of the washer of aspect A is the fastener of FIGS. 1 and 5. In reference to FIG. 8 together with FIG. 7, when comparing the vicinity of the position Pt (Ps) and the outermost peripheral portion of the nut, a larger stress is generated in the vicinity of the position Pt (Ps). A large amount of stress emerges from the position Pt (Ps) in the diagonal thread direction, and when it enters the inside of the nut, light gray and dark gray spread widely, and spread widely to the 3rd, 4th, and 5th threads on the open side of the nut thread. The 6th and 7th threads are black. On the other hand, the strength of the washer is white, light gray, and dark gray slightly diagonally from the position Pt (Ps) as the same material as the conventional method. The distribution is similar to the line 1 mg of the stress distribution equivalent to Mieses (see FIG. 11 (a)). This distribution state represents the flow of force.

Comparing FIGS. 8 and 4, it can be seen that the stress distribution states are significantly different. In FIG. 8, it can be seen that light gray and dark gray spread to the fifth mountain. A small white color can be seen in the diagonal thread direction from the vicinity of the washer position Pt (Ps), and this white color indicates the magnitude of stress, and the

nut thread threads

3, 4, 5 are in the direction of this white color. There is a mountain. With reference to FIG. 8, it can be seen that the stress is larger and the stress load sharing ratio of the first peak is smaller toward the open side as compared with FIG. The numerical value of the load sharing ratio is 30.2% for the first mountain, 19.4% for the second mountain, 15.2% for the third mountain, 12.6% for the fourth mountain, and 10. 3%, the 6th mountain was 7.4%, and the 7th mountain was 4.9%.

FIGS. 9 (a) and 9 (b) show the results of examining the load sharing ratio of each thread of FIG. 7. FIG. 9A shows a load sharing ratio of an example of the fastening structure of the present invention (FIG. 8), and a table comparing the load sharing ratios corresponding to FIG. 4 of the conventional washer fastening structure and FIG. 9B. The comparison is displayed as a bar graph. Comparing these two, the load sharing ratio of the first meshing thread of the conventional bolt is 35.6%, whereas the load sharing rate of the first meshing thread of the bolt of the present invention is 30. The absolute value is 2%, which is 5.4 points, and the relative ratio is about 15%. By reducing the load on the first thread, it is effective in improving the fatigue strength of the bolt meshing on the bottom of the first thread.

Fracture of bolt and nut fasteners often occurs as crack shaft fracture at the bottom of the first mountain valley where bolts mesh, but how is the reduction of the initial fastening load, which is said to have the effect of improving fatigue fracture strength, effective? Explain whether it will work. The SN diagram obtained from the bolt fatigue test results shows the relationship between the fatigue fracture life (repetition number Nf) and the external force load (stress amplitude σr), but it is generally shown by the following empirical formula. Can be done.
Nf · σr ^b = C
(In the formula, Nf: Number of repeated loads until fatigue failure σr: Stress amplitude of load b: Stress index (generally 3 to 5)
C: Material constant)
As shown here, lowering the load on the bottom of the bolt screw valley at the first thread of fastening mesh leads to lowering the share of the external force load (σr) at the same rate, and the stress amplitude of the lowered load b. (Generally 3 to 5) It leads to the effect that the number of repetitions Nf can be increased by a multiplication factor. Since the load sharing rate is reduced by 15%, it is expected that Nf is improved by 50 to 100% and the life is increased by 1.5 to 2 times from the above equation. When the stress index b = 4, the life is expected to increase about 1.9 times.

The elements such as thread shape, member strength, member Young's modulus, Poisson's ratio, fastening torque, and axial force, which are the boundary conditions for bolts, nuts, and washers used in the present invention for FEM analysis, are all the same as those of the conventional method. The improvement effect is confirmed by analyzing by adopting the one specified in JIS (ISO) and comparing. Finer details are used for the screw pitch. In the analysis shown in FIGS. 4 and 8, the case of M12 × P1.25 (fine screw) is displayed for reference. An example showing the third boundary line (B3) in a typical shape is shown in FIG. 8, and the FEM analysis result of an example in which Ls is changed with the same shape is shown in the interruption and the lower part of the right figure of FIG. The load sharing ratio is shown by converting it into a value with respect to Ls / p. The diameter of the bolt hole in the washer is set to the minimum gap (0.5 mm) for the screw to pass through, and the gap is the same as that of the conventional bolt hole and the bolt screw, and is straight. The distance Ls is about 2.21p (corresponding to 2.21 pitch), and the distance Lh is about 1.0p (1.0 pitch). The outer peripheral diameter of the seat surface of the nut is 24 mm.

An example of a preferable embodiment of the stress non-transmission space (1s) is shown in the vertical cross-sectional views of FIGS. 5 to 7, and the washer body (1b) is opened in the bolt hole (1h). The stress non-transmission space (1s) is three-dimensionally a concentric ring centered on the axis of the bolt hole (1h) of the washer (1) in the vertical cross-sectional view (see FIGS. 7 (b) and 7 (c)). ). That is, the stress non-transmission space (1s) is a three-dimensional space (concentric annular space) formed by rotating the cross-sectional space 1s shown in FIGS. 5 to 7 by 360 degrees around the axis. The stress non-transmission space (1s) with reference to FIGS. 5 to 7 is opened in the bolt hole (1h) in the vertical sectional view of the washer (1), so that the washer body (1b) is fastened on the bolt hole side. Since the transmission of the force in the axial direction is cut off, the force applied to the lower ridges of the fastening mesh of the bolt (3) on the bolt hole side is reduced.

Similar to FIG. 7, FIG. 10 shows the Mises equivalent stress applied when fastening the bolt (3) and the nut (4) in the example of the washer fastening structure on the first side surface by FEM analysis, and the distance Ls (Ls / Ls / It is a graph which summarizes the change of the stress load factor of the 1st mountain when p) is changed, and the Mises equivalent stress distribution map. With reference to FIG. 10, it is recognized that as the distance Ls (Ls / p) increases, the load sharing ratio of the first mountain becomes smaller. When Ls / p increases from 0 to 0.80, 2.21, 3.00, 3.41, and 3.81, the load sharing ratio of the first peak is 35. When Ls / p = 0. It decreased from 6% to 32.8%, 30.2%, 29.1%, 28.7%, and 28.3% in that order. Looking at the graph in FIG. 8 (b). Each number is on a downwardly convex curve. In the washer design, the user may select it as a design condition related to various conditions such as material, Young's modulus, and hardness.

From the relational expression of the SN diagram obtained from the bolt fatigue test results described above, the load sharing ratio is from 35.6% to 32.8%, 30.2%, 29.1%, 28.7%. When it decreases to%, 28.3%, the stress index b = 4, and the Nf and lifetime are about 1.39 times, about 1.92 times, about 2.22 times, about 2.33 times, about 2. It is expected to increase by 56 times.

FIG. 11 shows an example in which the force F is vertically applied at the position Pt, but in the relationship between the actual bolt, nut, and washer, the direction of the arrow F in FIG. 11 is the upper right with respect to the figure. It may go to the lower left from. The reason is that there is a bolt on the right side of the position Pt and there is a nut seat surface on the position Pt, so the bolt (3) and nut (4) pass the force at the thread, and the compressive force is the nut seat. This is due to stress concentration on the innermost peripheral portion (here, position Pt) of the contact portion between the surface and the washer (1). Therefore, for example, the stress line 1 mg of the Mises equivalent stress distribution curve also rotates slightly clockwise (in FIG. 8). This means that the entire compressive stress distribution including the stress line 1 mg is inclined and separated from the boundary line (B3) on the left half side of FIG. 11 in the clockwise direction, so that there is no adverse effect on the evaluation of the present invention. Looking at the Mises equivalent stress distribution diagram in FIG. 8, the region of white with high stress, light gray with slightly high stress, and dark gray with slightly weak stress is the force F near the position Pt where the nut bearing surface and washer (1) contact. It shows the direction and spreads in the washer (1) and nut (4). The direction of this stress appears to be from the position Pt toward the fourth thread of the screw.

(Suitable stress non-transmission space; Aspect A)
In one preferred embodiment of the first aspect of the present invention, it has been found that the stress non-transmission space (1s) is preferably the first stress non-transmission space (11s) satisfying the following conditions (this). Aspects are referred to as Aspect A). That is, the first stress non-transmission space (11s) has a vertical cross section including the axis of the washer (1) as shown in FIGS. 5 to 7, and particularly when referring to FIG.
-The extension line of the upper plane (1u) of the washer body (1b) is set as the first boundary line (B1), and the extension line of the inner peripheral surface (1i) of the bolt hole is set as the second boundary line (B2). The third boundary line is a line that is below B1) and radially outside the second boundary line (B2) and connects the position Pt of the first boundary line (B1) and the position Ph of the second boundary line (B2). The space to be referred to as (B3), in the first stress non-transmission space (11s), the position farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole is Ps, and preferably the position Pt is the position Ps.
The radial distance Ls from the position Ps to the extension line (4e) of the line connecting the screw valley bottoms of the nut (4) exceeds 0.5 times the screw pitch p of the nut (4) and is 6 times or less. In the range of length,
The distance Lh in the axial direction from the first boundary line (B1) to the position farthest in the axial direction of the first stress non-transmission space (11s), preferably the first boundary line (B1) is the second boundary line (B2). The position where it intersects with () is Po, and the distance in the axial direction from the position Pо to the position Ph is the distance Lh, but the thickness T of the washer (1) is 0.01 times or more the screw pitch p of the nut (4). It is in the range of 99% or less of.

The vertical sectional views of FIGS. 5 to 7 show an example of a preferable mode of the first stress non-transmission space (11s), but the washer body (1b) is opened in the bolt hole (1h) and also in the upper plane (1u). It has a first stress non-transmission space (11s) that opens. The first stress non-transmission space (11s) is not open to the lower plane (1w) of the washer body (1b). In the vertical cross section of the washer (1), the third boundary line (B3) between the first stress non-transmission space (11s) and the washer body (1b) is the inner peripheral surface (1i) of the bolt hole from the position Pt of the upper plane (1u). ) (A surface defining the bolt hole (1h)), which is a convex stress concentration relaxation curve connected to the position Ph. In FIGS. 5 to 7, the third boundary line (B3) is an arc or an elliptical arc. If it is an arc, the center point is directly below the Pt passing through the inside of the washer, and if it is an elliptical arc, Pt is preferably the apex of the minor axis of the ellipse. Further, since the force from the nut (4) is applied near the position Pt of the upper plane (1u), the connection method between the upper plane (1u) and the third boundary line (B3) is also a stress concentration relaxation curve. Is desirable, and it is important that the stress concentration relaxation curve has no corners and moves from the straight line of the upper plane (1u) to the third boundary line (B3) with a gentle curve. On the other hand, the connection method between the third boundary line (B3) and the bolt hole inner peripheral surface (1i) near the position Ph of the bolt hole inner peripheral surface (1i) is from the nut (4) and the object to be fastened (2). Since almost no force is applied, it does not necessarily have to be a stress concentration relaxation curve. For example, the third boundary line (B3) may start with an upwardly convex curve from the position Pt and inflection to form a downwardly convex curve to reach the position Ph, as shown in FIG.

In this embodiment, the first stress non-transmission space (11s) has an upwardly convex cross-sectional shape shown in FIGS. 5 to 7 in the vertical cross section, but three-dimensionally, the bolt hole (1h) of the washer (1) ) Is a concentric ring centered on the axis (see FIGS. 7B and 7C). That is, the first stress non-transmission space (11s) is a three-dimensional space (concentric annular space) formed by rotating the cross-sectional space (11s) shown in FIGS. 5 to 7 by 360 degrees around the axis. ..

With reference to FIGS. 5 to 7, the first stress non-transmission space (11s) is opened in the bolt hole (1h) in the vertical cross section of the washer (1). Since the first stress non-transmission space (11s) is opened in the bolt hole (1h), the transmission of the fastening force on the bolt hole side of the washer body (1b) in the axial direction is blocked, so that the fastening force is blocked on the bolt hole side. The force applied to the lower ridges of the fastening mesh of a certain bolt is reduced. The first stress non-transmission space (11s) is also open to the upper plane (1u) of the washer body (1b) in the vertical sectional view of the washer (1). Since the first stress non-transmission space (11s) is also open to the upper plane (1u) of the washer body (1b), it is located near the low-order threads of the nuts (4) and bolts (3). The effect of reducing the force applied to the lower-order ridges of the bolt (3) is strong and reliable, and the load reduction effect can be strong and reliable even if the depth of the space is small. The formation of the space in 1b) is also easy.

When the first stress non-transmission space (11s) has a radial distance Ls, the fatigue strength of the first mountain valley bottom where the bolt (3) meshes due to the lower order of the bolt (3), especially the load reduction of the first mountain The effect is greater as the distance Ls is larger, but the effect is gradually saturated. In one preferred embodiment, the distance Ls is, for example, 0.8 times or more, 1 time or more, 1.5 times or more, 2 times or more, 2.5 times or more the length of the screw pitch p of the nut (4). It may be in the range of 3 times or more, 5 times or less, 4 times or less, and 3.5 times or less. In particular, it is preferably 2.0 times or more and 4 times or less.

The axial distance Lh of the first stress non-transmission space (11s) is set so as to secure a space in which Ph does not come into contact with the nut bearing surface even if the washer (1) is elastically deformed, and the screw pitch is set. It may be as shallow as 0.01 to 0.1 times, and may be deep to reduce the weight of the washer (1). In one preferred embodiment, the distance Lh is, for example, in the range of 0.1 times or more the screw pitch p of the nut (4) to 90% or less of the following thickness T of the washer (1), and further 1 of the screw pitch p. The range may be from double or more to 65% or less of the thickness T of the washer (1). It is preferably in the range of more than 0.01p and 65% or less of the washer thickness T, and more preferably in the range of more than 0.03p and 50% or less of the washer (1) thickness T. More preferably, it exceeds 0.04p and is in the range of 40% or less of the thickness T of the washer (1). The distance Lh is a distance on the inner peripheral surface (1i) of the bolt hole. The distance Lh may be the longest distance in the axial direction of the first stress non-transmission space (11s), but may not be the longest distance in the axial direction of the first stress non-transmission space (11s). Regardless of whether the distance Lh is the longest distance in the axial direction of the first stress non-transmission space (11s), the longest distance in the axial direction of the first stress non-transmission space (11s) is the nut (4). It is preferable that the thickness T of the washer (1) is 99% or less from 0.01 times the screw pitch p of.

In one preferred embodiment, the longest distance in the axial direction of the distance Lh or the first stress non-transmission space (11s) is from 0.5 times or more the screw pitch p of the nut (4) to the thickness of the washer (1). It is in the range of 95% or less of T, and may be in the range of 30 to 90% and 50 to 90%. The longest distance in the axial direction of the distance Lh or the first stress non-transmission space (11s) may be 1% or more, 3% or more, 5% or more, 10% or more of the thickness T, and the thickness T. It may be 50% or less, 30% or less, 20% or less, 10% or less, and 5% or less.

The mode having the stress non-transmission space (1s) and the first stress non-transmission space (11s) has been described above, but by referring to the Mises equivalent stress evaluation results in FIGS. 8 to 10, the distance Ls ( As already described, the stress load sharing ratio of the first peak becomes smaller as the Ls / p) increases.

(Mises equivalent stress distribution)
In the washer fastening structure of aspect A of the first side surface, in one preferred embodiment, the third boundary line (B3) of the first stress non-transmission space (11s) is formed on the upper plane (1u) of the washer body (1b). When such a fastening force is applied to a washer (1) assuming that the upper plane (1u) of the washer (1) is flat from the position Pt to the position Po, it is generated in the washer (1) of the above assumption. In the stress distribution corresponding to Mieses, the relative stress is 95% on the bolt hole side of the stress distribution line on the bolt hole side with reference to the magnitude of the Mieses equivalent stress applied vertically downward from the position Pt.

The Mises equivalent stress distribution is a technique for visualizing the state of force inside a ductile material that cannot be actually seen. It subdivides the inside of a substance, calculates a vector in three axial directions, and expresses it collectively. Therefore, the direction of the internal force and the magnitude of the force (stress) are expressed as a distribution. It is a method known in strength of materials, and a typical formula is as follows, and the Mises stress σMises is expressed by the following formula using the principal stresses σ ₁ , σ ₂ , and σ ₃ .

In the present invention, the present invention uses the Mises equivalent stress distribution in order to improve the conventional method according to the purpose by comparing the states when the bolts, nuts, and washers are fastened with the axial force specified by JIS. The fastening structure of the invention was evaluated.

All the axial forces of the bolts generated at the time of fastening mesh unevenly over the entire ridge that contacts the nut, transfer the force equivalent to the axial force to the nut, and the sum of the forces that are unevenly shared by the ridges of the nut is the nut. After passing through the inside, it becomes a stress that compresses the entire contact surface with the washer. The total bolt axial force is equal to the sum of the forces received on the entire surface of the washer. Although one vertical section is shown in FIGS. 4 and 8, the analysis is performed at 1/360 degree, which is consistent with the sum of 360 degrees. In addition, the stress applied to the washer is never even, and is concentrated on the inner peripheral side of the nut (bolt side) or at a considerably higher ratio (from various simulation results) on the inner peripheral side of the nut, and on the outer peripheral side of the nut. The load sharing is small (there are many black parts in the simulation). Therefore, even if it is considered that the parts are concentrated on the contact point Pt between the nut and the washer on the inner peripheral side, by arranging many members of the washer body on the bolt hole side of the washer, it becomes stronger and the washer can be prevented from buckling. It has a safe fastening structure.

As the first element of the fastening structure of the first side surface of the present invention, in the examples of FIGS. 6 and 8, from the line (4e) connecting the screw valley bottoms of the nut (4), the nut bearing surface (4w) and the washer There is a distance Ls to the position (point) Pt where (1) starts to touch. The maximum load is applied to this position Pt, and the maximum compressive stress is generated immediately below the position Pt.

The stress distribution 1 m equivalent to Mises in FIG. 11 (a) is generally a post-processing of the calculation by FEM analysis of the distribution state of the compressive stress generated inside the washer when a force is applied perpendicularly to the position Pt. It is expressed as. In FIG. 11A, the third boundary line (B3) is also shown, but in the present invention, the washer (1) provides a flat upper plane (1u) without the first stress non-transmission space (11s). Assuming that it has, when a force F is applied to the position Pt (boundary with the first stress non-transmission space (11s)) on the upper plane (1u) of the assumed washer (1), the assumed washer (1). The Mises equivalent stress distribution applied to the inside of) is used as a reference, and FIG. 11A also schematically shows the Mises equivalent stress distribution obtained in this way. The stress distribution equivalent to Mieses depends on the Young ratio and Poisson ratio of the washer, and the magnitude of the stress depends on the force F, but the stress distribution situation is based on the relative stress distribution that does not depend on the magnitude of the force F. As shown, an arrow curve 1 m (specifically, 1 ma to 1 mg; a vector indicating the magnitude and direction of the force, which represents the stress distribution equivalent to Mieses shown in FIG. 11 (a), is a vector indicating the magnitude and direction of the force. The stress 1 ma in the innermost part (immediately below Pt) is the largest, and the stress increases as the stress increases to the outside and farther from the inside of the semicircle, which is the range in which the force diffuses. It becomes smaller in order (from 1 mb to 1 mg). In FIG. 11A, the third boundary line (B3) is an example formed on the side (bolt hole side) farther than the smallest stress line 1 mg from the Pt direct perpendicular line. However, although the stress line 1 m (1 ma to 1 mg) in FIG. 11A represents a stress distribution in seven stages, it is schematically an arbitrary stress distribution.

FIG. 11B shows the magnitude of the force in this state actually obtained and shown in an eight-step gradation pattern using black (high stress), gray, light gray, and white (low stress). The darker the color, the larger the stress. In the display, the stress of 1 ma directly below the central portion Pt to which the force F is applied is the largest, and the portion of the outermost line 1 mg from the position Pt is the smallest. This stress further extends to the outside of the outermost circumference line 1 mg, but the magnitude of the stress outside the outer circumference line 1 mg (on the right side of the line 1 mg in the figure) is extremely small, and the influence as stress can be ignored. It is getting smaller. The inside of the outermost circumference line 1 mg (inside of a substantially semicircle) in the figure shares 95% or more of the total load F. If the third boundary line (B3) of the first stress non-transmission space (11s) is in a region far from the position Pt and the Mises equivalent stress is smaller, the stress that is not shared by the first stress non-transmission space (11s) is Since only the small stress is applied, the stress applied to the washer body (1b) can be made smaller, so that the strength of the washer can be improved and buckling of the washer can be prevented or reduced.

In a typical bolt hole structure of a conventional washer, the end of the washer (1) on the bolt hole side is perpendicular to the upper plane (1u) of the washer (1) and is in the axial direction of the bolt (3). The structure was such that the bolt hole end was 100% directly underneath the entire stress of the force F applied to the bolt hole end. In the first aspect of the present invention, the third boundary line (B3) forming the first stress non-transmission space (11s) of the washer (1) is added directly below the position Pt in the above-mentioned Mieses equivalent stress distribution curve. When the stress is 95%, 90%, or even smaller on the bolt hole side than the stress distribution curve, the force applied to the position Pt is shared on the bolt hole side from directly below the position Pt, so that the fatigue strength of the washer 1 is improved. When the third boundary line (B3) is on the bolt hole side of the 95% stress distribution curve of the magnitude of the Mieses equivalent stress 1 ma applied directly under the position Pt, the 95% stress distribution curve is shown in FIG. 11 (a). Is a line that is almost vertical from the upper plane 1u to the lower plane 1w, for example, 1 mb, but in many cases, the third boundary line (B3) depends on the condition of the distance Ls / p = 0.5 to 6. Even if it follows a stress distribution curve such as 1 mb, it will bend somewhere along the way and extend to the bolt hole side. The third boundary line (B3) is the stress distribution of 80%, 70%, 50%, 30%, 20%, 10%, or 5% of the stress applied directly under the position Pt in the Mises equivalent stress distribution curve. It may be on the bolt hole side of the curve. It is particularly preferable that the boundary line B3 is on the bolt hole side of the Mises equivalent stress distribution curve with respect to the stress distribution curve of 5% of the stress applied immediately below the position Pt.

Further, when the third boundary line (B3) is on the bolt hole side of the stress distribution curve equivalent to Mieses immediately below the position Pt, for example, the stress distribution curve of X%, the third boundary line (B3) Does not have to completely follow the X% stress distribution curve 1 m, it may be on the bolt hole side of the X% stress distribution curve, especially from the upper plane to the lower plane of the washer (1) to a predetermined depth. After extending (usually with an upwardly convex curve), while maintaining the stress deconcentration line, toward the bolt hole side (in the direction parallel to the upper plane of the washer (1), that is, downward) It may be bent (as a convex curve). For example, the third boundary line (B3) in FIG. 11 initially follows the stress distribution curve 1 mg in the depth direction from the position Pt (upwardly convex curve), but bends toward the bolt hole at a predetermined depth. It extends (through the inflection point and toward the bolt hole in a downwardly convex curve). In a typical example, the third boundary line (B3) in the longitudinal section may be configured to start as an upwardly convex curve from position Pt and inflection to reach position Ph as a downwardly convex curve. (Here, an upwardly convex or downwardly convex curve means that a straight line connecting any two points of the curve has a point between the two points above or below the straight line, respectively, with respect to the curve. The tangents are above or below, respectively). Since the third boundary line (B3) is such a curve, the washer (1) is near the bolt hole of the washer body (1b) while achieving a small stress concentration by the first stress non-transmission space (11s). The decrease in strength can be reduced, the amount of processing for forming the first stress non-transmission space (11s) can be reduced, and it can be advantageous for alignment with the bolt (3). The third boundary line (B3) is on the bolt hole side of the stress distribution curve of 5% of the stress applied directly under the position Pt in the stress distribution curve equivalent to Mieses, and is near the upper plane (1u) of the washer (1). It is particularly preferable to bend the bolt hole side from a position where the depth reaches a certain magnification (for example, 0.01 times to 0.03 times) or more of the screw pitch while following the stress distribution curve of 5%.

With reference to FIG. 11 (b), the radial dimension of the distribution state of the specific stress magnitude initially expands in the depth direction, but the vector line (1 m) through which the force flows as shown in FIG. 11 (a). ) Spreads to about 45 degrees, the large stress in the center of FIG. 11B gradually propagates and expands, and the region where the stress is slightly weakened is gradually expanded around. The black range, which represents the maximum stress, is reduced from the middle. When the radial dimension of the third boundary line (B3) is reduced in the middle of the depth direction (in the direction of 1 ma in FIG. 11 (a), for example, to 1 mc), the third boundary line (B3) is reduced most. The stress of the stress distribution curve closest to the position Pt (the stress distribution curve closer to the position Pt than the shrinking stress distribution curve above) that intersects when the line in the axial direction is drawn from the position is applied to the object to be fastened (2). It takes. Therefore, for the purpose of the present invention, the Mises equivalent stress distribution range may be considered as a straight line extending from that position to the lower surface in the axial direction at a position deeper than the position where the radial dimension is maximized.

In FIG. 11B, at the third boundary line (B3), even if the radial dimension of the stress large range of the stress distribution diagram is reduced in the depth direction, the stress of the surrounding stress is propagated. Since it is enlarged, it is not preferable that the radial dimension of the third boundary line (B3) is reduced. Basically, the third boundary line (B3) expands in the bolt hole direction from the position Pt and reaches Ph, and the third boundary line (B3) from the position Pt to Ph decreases in the depth direction. It is preferable that there is nothing, and that it only expands. Alternatively, since the relative stress of the stress distribution differs in magnitude between the upper part (near Pt) and the lower part (near the arrow of the arrow in the figure) of the curved arrow, in one embodiment, the lower surface of the object to be fastened (2) or the screw. It may be evaluated at a pitch of 10 to 20 p or more. In another aspect, the evaluation may be performed from the nut-side plane of the object to be fastened (2) to a depth of 0.1 to 1 pitch or 1 to 2 pitch of the screw.

On the contrary, in the vertical cross section, the region where the third boundary line (B3) of the first stress non-transmission space (11s) should not exist is a small region from the line 1ma directly under Pt to the bolt hole side. It is preferable that the length of the third boundary line (B3) starting from the position Pt in the radial direction toward the bolt hole is, for example, a stress concentration relaxation curve with a screw pitch of 0.01p to 0.5p. The stress concentration relaxation curve has been described above. For example, since the point where the first boundary line (B1) and the third boundary line (B3) meet is Pt, the contact form is the third boundary line (B3). Is a part of an arc or elliptical arc as a stress concentration relaxation curve, and it is desirable that is tangent to the arc or elliptical arc at the Pt position. If it is an arc, the center of the circle is below Pt, and if it is an ellipse, Pt is the apex of the minor axis.

Further, the third boundary line (B3) starting from the position Pt is preferably a stress concentration relaxation curve from the position Pt toward the bolt hole side at least from a screw pitch of 0.01p to 0.5p. The hole side does not necessarily have to be the stress concentration relaxation curve.

(Modification example of aspect A of the first stress non-transmission space)
FIG. 12 shows a modified example of the first stress non-transmission space (11s) in a vertical sectional view. For example
FIG. 12A is composed of one ellipse or a part of a large arc.
-In FIG. 12 (b), the first stress non-transmission space (11s) is formed symmetrically on both planes of the washer (1), and both both sides of the washer (1) can be used as upper planes. As a feature of FIG. 12 (b), the third boundary line (B3) forming the first stress non-transmission space (11s) is extended downward by the required amount from Pt to the bolt hole side via the turning point. It is composed of a convex, for example, a part of an arc, returns to the upper plane (1u) side of the washer, and extends (in the radial direction) to the bolt hole side in the middle (as long as it does not touch the upper plane (1u) of the washer). It is a shape that reaches Ph in the bolt hole. It has a shape that requires a small amount of processing during washer manufacturing and is easy to center with bolts.
In FIG. 12 {c), an asymmetric first stress non-transmission space (11s) is formed on both planes of the washer (1), but either side of the washer (1) can be used as the upper plane. When an asymmetric first stress non-transmission space (11s) is formed on both planes of the washer (1), either side of the washer (1) may be used as the upper plane, but it is formed on the upper plane. There is a possibility that the stress non-transmission space acts as the first stress non-transmission space, or the stress non-transmission space formed on the lower plane acts as the second stress non-transmission space. The stress non-transmission space having the larger distance Ls functions as a substantial stress non-transmission space. In this case, the compressive force passes between the position Pt where the washer (1) touches the nut (4) and the point where it touches the object to be fastened (2), and the bolt hole side (so-called peninsula shape) from between these two points. The protruding part (of) exists as a part for centering with the bolt.
12 (d) shows a curved shape in which the central portion is wavy or partially recessed. There may be various other shapes.
In FIG. 12 (e), the position Ps farthest in the radial direction from the bolt hole (1h) in the first stress non-transmission space (11s) is the first stress non-transmission space (11s) in the upper plane (1u) of the washer. This is an example in which the position is farther from the bolt hole (1h) than the position Pt forming the boundary point with.

(Suitable stress non-transmission space; aspect B)
As one aspect of the first aspect of the present invention, it has been found that the stress non-transmission space (1s) is preferably a second stress non-transmission space (12s) satisfying the following conditions (this aspect). Is referred to as aspect B). That is, the second stress non-transmission space (12s) is the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section including the axis of the washer (1) as shown in FIGS. 13 to 15 and 19. The line extending outward in the radial direction from the position P1 to the position P2 on the inner peripheral surface (1i) of the bolt hole or to the position P3 on the lower plane (1w) of the washer body (1b) is the fourth boundary line (B4). ), The extension line of the inner peripheral surface (1i) of the bolt hole is the fifth boundary line (B5), or optionally, the extension line of the lower plane (1w) of the washer body (1b) is the sixth boundary line (B6). It is a space to do
The second stress non-transmission space (12s) has a vertical cross section.
-Preferably, the position farthest in the radial direction from the peripheral surface (1i) of the bolt hole is Ps, and the radial distance Ls from the position Ps to the cylindricity of the line connecting the thread valley bottom of the nut is the screw of the nut (4). It is in the range of length exceeding 0.5 times the pitch p and 6 times or less.
The eaves thickness Th, which is the shortest dimension in the axial direction from the upper plane (1u) of the washer body (1b) to the second stress non-transmission space (12s), is 1% of the thickness T of the washer (1). That is all.

The vertical cross-sectional view of FIGS. 13 to 15 shows an example of a preferable embodiment of the second stress non-transmission space (12s), but the washer body (1b) is opened in the bolt hole (1h) and also in the lower plane (1w). It has a second stress non-transmission space (12s) that opens. The second stress non-transmission space (12s) is not open to the upper plane (1u) of the washer body (1b). The fourth boundary line (B4) between the second stress non-transmission space (12s) and the washer body (1b) has a rising edge (Br) that rises almost vertically from the lower plane (1w), and is a curved corner close to an arc. The end of the inner circumference of the bolt hole that approaches the upper plane (1u) in the portion (Bc) and extends from the corner portion (Bc) to the inner peripheral surface (1i) of the bolt hole of the washer body (1b) (the surface that defines the bolt hole (1h)). It ends with (Be) and forms a washer (1p) on the upper side of the second stress non-transmission space (12s), particularly on the upper side of the inner peripheral end portion (Be) of the bolt hole. The rising portion (Br) rising substantially vertically from the lower plane (1w) may be within an angle of ± 20 degrees with respect to the vertical direction in consideration of manufacturing accuracy. The corner portion (Bc) is not limited, but in the vertical sectional views of FIGS. 13 to 15, the line segment of the corner portion (Bc) is 20 to 25 degrees, particularly 25 degrees with respect to the axis z. It may be a portion from a position in contact with a straight line to be formed to a position in contact with a straight line forming 65 to 70 degrees, particularly 65 degrees with respect to the axis z. The end of the inner circumference of the bolt hole (Be) is from the end of the corner (Bc) (the position in contact with the straight line forming 65 to 70 degrees, particularly 65 degrees with respect to the axis z) to the inner peripheral surface of the bolt hole (1i). is there.

In this aspect, the second stress non-transmission space (12s) has an upwardly convex cross-sectional shape shown in FIGS. 13 to 15 in the vertical cross-sectional view, but three-dimensionally, the bolt hole of the washer (1) ( It is a concentric ring centered on the axis of 1h) (see FIGS. 15B and 15C). That is, the second stress non-transmission space (12s) is a three-dimensional space (concentric annular space) formed by rotating the cross-sectional space shown in FIGS. 13 to 15 by 360 degrees around the axis.

With reference to FIGS. 13 to 15, the second stress non-transmission space (12s) is opened in the bolt hole (1h) in the vertical cross section of the washer (1). Since the second stress non-transmission space (12s) is opened in the bolt hole (1h), the axial transmission of the fastening force on the bolt hole side of the washer body (1b) is reduced, so that it is on the bolt hole side. The force applied to the lower ridges of the fastening mesh of a certain bolt (3) is reduced.

When the washer of aspect B is used together with the nut, the fastening force (compressive stress) from the contact surface between the washer (1) and the nut (4) to the bolt (3) is determined by the presence of the second stress non-transmission space (12s). (Ii) The angle (direction in which the compressive stress extends to the bolt hole side) from the outside of the position Ps farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the stress non-transmission space (12s) to the bolt hole side is upright from the position Ps. The limit is an elevation angle of approximately 45 degrees with respect to the axis z from the vicinity of passing through the upper portion (Br) and beyond the apex of the curve at the corner portion (Bc). By directing the wraparound compressive stress toward the higher ridges (particularly the summit) of the bolt, the load sharing of the lower ridges (particularly the first ridge) of the bolt can be reduced.

Radial direction from the position Ps farthest in the radial direction from the inner peripheral surface (1i) of the bolt hole in the second stress non-transmission space (12s) to the line (4e) connecting the screw valley bottom of the bolt hole (1h) of the nut (4). The distance Ls is preferably 0.5 times or more and 6 times or less the length of the screw pitch p of the nut. In one preferred embodiment, the distance Ls is 0.7 times or more, 1 time or more, 1.5 times or more, 2 times or more, 2.5 times or more, 3 times or more the length of the screw pitch p. Further, it is preferably 5 times or less, 4.5 times or less, 4 times or less, and 3.5 times or less. It is particularly preferable that the distance Ls is 2 pitches or more and 4 pitches or less. When the radial dimension of the second stress non-transmission space (12s) is set to an appropriate dimension or less, the outer diameter dimension of the nut and washer can be kept small while the stress applied to the low-order thread is sufficiently small. It is preferable because it can be done.

In the vertical cross-sectional views of FIGS. 13 to 15, the washer body (1b) has an eaves portion (1p) above the second stress non-transmission space (12s). The eaves portion (1p) is a member for centering the bolt (3) with respect to the bolt hole (1h), and the tip of the eaves portion (1p) constitutes the inner peripheral surface of the bolt hole (1h). Just do it. The eaves portion (1p) forming the inner peripheral surface of the bolt hole (1h) does not necessarily exist on the entire circumference of the bolt hole (1h) in the plan view of the washer body (1b), but exists on the entire circumference. It is preferable to define a circular bolt hole (1h). Since the eaves (1p) is not a part that transmits stress, the vertical thickness in the figure may be as small as long as the strength of the eaves (1p) is maintained, and the smaller the thickness, the more the contribution to stress transmission. Is preferable because For example, the minimum thickness Th of the eaves portion (1p) is 1% or more of the thickness T of the washer, but it is desirable that it is 0.1 times or more and 0.7 times or less. More preferably, Th is 0.2T ≦ Th ≦ 0.6T, and even more preferably 0.22T ≦ Th ≦ 0.5T. The thickness of this eaves 1p can be partially reduced, and if the shape is the thinnest on the way to the inner peripheral surface Ii of the bolt hole through the corner Bc, centering with the bolt on the innermost diameter side It is possible to secure the length t of the inner peripheral surface that can be easily performed.

With reference to the vertical sectional views of FIGS. 13 to 15, the fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is approximately the same as the lower plane (1w) of the washer body (1b). Between the rising portion (Br) that rises vertically, the bolt hole inner peripheral side end (Be) connected to the bolt hole inner peripheral surface (1i), and the rising portion (Br) and the bolt hole inner peripheral end (Be). It has a corner portion (Bc) to be connected. The fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s), particularly the upwardly convex curve in FIGS. 13 to 15, but the corner portion (Bc) is entirely curved or It is preferably composed of a combination of curved lines and straight lines, and is composed of stress concentration relaxation lines having no corners where the straight lines intersect. In the vertical cross-sectional view of FIGS. 13 to 15, the corner portion (Bc) is not limited, but is 20 to 25 degrees with respect to the axis z, particularly from a position in contact with a straight line forming 25 degrees with respect to the axis z. It may be a portion up to a position tangent to a straight line forming 65 to 70 degrees, particularly 65 degrees, and there is a position where a straight line having an elevation angle of 45 degrees with respect to the axis z touches the fourth boundary line (B4). It is a part. The corner portion (Bc) may be composed of, for example, a straight line having an elevation angle of about 40 to 50 degrees, particularly about 45 degrees. In that case, the connecting portion between the corner portion (Bc) and the rising portion (Br), It is preferable that the connecting portion between the corner portion (Bc) and the inner peripheral side end portion (Be) of the bolt hole is joined by a curved line so as not to form a corner. Further, the corner portion (Bc) may be formed by an arc, an elliptical arc, or a shape close thereto. How to connect the lower plane (1w) of the washer body (1b) to the fourth boundary line (B4), and the connection between the inner peripheral surface of the bolt hole (1i) of the washer body (1b) and the fourth boundary line (B4). Although it is preferable that the stress concentration relaxation line is used, the connection point between the inner peripheral surface (1i) of the bolt hole of the washer body (1b) and the fourth boundary line (B4) is a nut. It does not have to be a stress concentration relaxation line because the force applied between the objects to be fastened hardly reaches or is small.

In one embodiment, referring to the vertical cross-sectional views of FIGS. 13 to 15, the fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is the lower plane of the washer body (1b). From the rising portion (Br) rising almost vertically from (1w), a corner portion (Bc) is formed by being connected to an arc or an elliptical arc, and then the inner peripheral surface of the bolt hole is formed by the inner peripheral end portion (Be) of the bolt hole whose curvature is further reduced. (1i) may be reached. Such a fourth boundary line (B4) is a stress concentration relaxation curve except for the connection point with the lower plane (1w) and the inner peripheral surface of the bolt hole (1i), and is a second stress non-transmission space having this shape (1i). 12s) is easy to form. Further, when the position P where the straight line having an elevation angle of 45 degrees with respect to the axis is in contact with the corner portion (Bc) is close to the upper plane (1u), the compressive stress transmitted from the object to be fastened (2) to the screw is not transmitted as the second stress. The position around the outside of the space (12s) has an effect of being farther from the inner peripheral surface (1i) of the bolt hole, which is preferable. The position P where the corner portion (Bc) is in contact with a straight line having an elevation angle of 45 degrees with respect to the axis is located at an axial distance of 1/2 or more of the thickness T of the washer (1) from the lower plane (1w) of the washer body (1b). It is preferably less than or equal to the length of one pitch of the screw from the position P3 (Ps) of the starting point of the rising portion (Br) on the lower plane (1w) of the washer body (1b) toward the inner peripheral surface (1i) of the bolt hole. It is preferable to have. The rising portion (Br) (from the lower plane (1w) to the position where a straight line having an elevation angle of 20 to 25 degrees with respect to the axis touches the fourth boundary line (B4)) is not limited, but is 1 of the thickness T of the washer (1). It is preferable to have an axial length of / 4 to 1/3 or more. The end of the inner circumference of the bolt hole (Be) (from the position where the straight line with an elevation angle of 65 to 70 degrees with respect to the axis touches the fourth boundary line (B4) to the inner peripheral surface of the bolt hole (1i)) is the connection point with the corner (Bc). The shape is such that the elevation angle formed by the tangent line with respect to the axis gradually increases from the bolt hole inner peripheral surface (1i), and the maximum elevation angle is preferably 90 degrees or less. The minimum thickness of the eaves (1p) formed above the bolt hole inner peripheral end (Be) (thickness t of the bolt hole inner peripheral surface (1i) in FIG. 14) is the thickness T of the washer (1). It is preferably in the range of 3 to 20%, more preferably 5 to 15%. The bolt hole inner peripheral end portion (Be) may have various deformations as shown in FIGS. 19 and 20, in addition to the shape shown in FIG. 13, and further, the bolt hole inner peripheral end portion (Be) does not exist. In addition, the middle or the end of the corner portion (Bc) may be a connection portion with the inner peripheral surface (1i) of the bolt hole.

(FEM analysis result of washer fastening structure of aspect B)
FIG. 16 shows the stress situation shown by the Mises equivalent stress distribution by performing FEM analysis on the washer fastening structure of the aspect B shown in FIGS. 13 to 15. There is white (high stress) diagonally around the position corresponding to the position P on the corner (Bc) of the fourth boundary line (B4) shown in FIG. 13, the compressive stress is large, and the thread faces the fourth direction. It can be seen that Light gray (slightly large stress) spreads, and the nut threads are applied to the 2nd to 5th threads. Looking at the bolt side, white (high stress) is on the first and second threads of the bolt screw, but the area is small. Light gray is No. 3, and dark gray (slightly small stress) extends widely to the 5th and 6th ridges at the end of the bolt. In this way, stress spreads to many parts of the nut (4), and the bolts (3) and nuts (4) exert forces on many of the threads. Looking at the washer (1), the stress is contained in the washer, and the small black stress portions are on the outer peripheral side and the inner peripheral side (bolt side) of the washer (1). No adverse effects such as seat deformation have occurred here.

17 (a) and 17 (b) show the results obtained by FEM analysis in the case of fastening with the washer fastening structure of the aspect B shown in FIG. 16 and the case of fastening with a conventional washer. A comparison of the load sharing ratios of the mountains is shown in a list, and the comparison is shown in a bar graph in FIG. 17 (b). The load sharing ratio at the first thread of fastening engagement is 35.6% in the case of the conventional structural washer, whereas it is 32.3% in the first thread in the model of aspect B (examples of FIGS. 13 to 15). The absolute value is reduced by 3.3 points, and the relative value is reduced by about 9%.

Aspect B is equivalent to increasing the ratio (Ls / p) of the radial distance Ls of the second stress non-transmission space (12s) to the pitch p, that is, increasing Ls, but the first meshing peak. The load sharing ratio of the thread tends to decrease. The reason is that the force from the washer is applied to the nut bearing surface on the outer peripheral side of the position Ps (P3), which is the end of the distance Ls, and the force from the input position toward the nut thread increases diagonally, and the nut This is because the stress increases after the third thread on the open side of the thread, so that the load sharing ratio that enters the first thread decreases relatively.

FIG. 18 shows the relationship between the change in the distance Ls (Ls / p) of aspect B and the load sharing rate of the first mountain of meshing. FIG. 18 summarizes the effects of changing the washer distance Ls of aspect B. The upper right figure of FIG. 18 is a Mises equivalent stress distribution diagram of a conventional structure washer fastening (Ls = 0), the middle row is a Mises equivalent stress distribution diagram of model 2 (Ls = 2.21p), and the lower row is a model 3 (Ls = 3). It is a Mises equivalent stress distribution diagram of .00p). In model 2 and model 3, the shape of the second stress non-transmission space (12s) has the same depth to the inner peripheral surface of the bolt hole (1i), and the distance Ps (up to position P3) in model 3 compared to model 2 Distance) is longer in the radial direction. With reference to these Mises equivalent stress distribution maps, it can be seen that the white portion having a large stress extends from the first thread to the higher-order thread side from the upper figure to the middle figure and the lower figure. From these figures, the load sharing ratio for the first thread of the bolt screw at each black spot position is 35.6% in the upper figure (conventional washer), 32.3% in the middle figure, and 30.9% in the lower figure. It was. It was shown that the load sharing ratio of the first thread of the screw decreases substantially linearly as the distance Ls increases, and the load sharing ratio of the first thread of the bolt screw decreases from 35.6% to 32.3% as the distance Ls increases. It has decreased by about 9% relatively. By reducing the load on the first thread, it is effective in improving the fatigue strength of the bolt meshing on the bottom of the first thread. From the relational expression of the SN diagram obtained from the bolt fatigue test results described above, the load sharing ratio is from 35.6% to 34.5%, 32.3%, 30.9%, 30.3. When it decreases to% and 29.7%, respectively, the stress index b = 4, and the Nf and lifetime are about 1.12 times, about 1.45 times, about 1.75 times, about 1.92 times, and about 2. It is expected to increase by 13.13 times.

(Modification example of aspect B of the second stress non-transmission space)
19 (a) to 19 (d) and FIG. 20 show a schematic diagram of a modified example of the second stress non-transmission space (12s). In FIG. 19, the fourth boundary line (B4) is the boundary line between the washer body (1b) and the second stress non-transmission space (12s).
FIG. 19A is an example in which the axial length t of the inner peripheral surface (1i) of the bolt hole is longer than the minimum thickness Th of the eaves portion (1p).
FIG. 19B shows the structure of the stress concentration relaxation curve from the contact position P3 (Ps) to the rising portion (Br) of the lower plane (1w) of the object to be fastened (2) and the washer (1). An example of the attached one is shown, and the length of the second stress non-transmission space (12s) in the radial direction in this case is more radial outside than the rising portion (Br) as shown in the figure.
FIG. 19 (c) shows a second stress non-transmission space (12s) that is convex from the inner peripheral surface of the bolt hole toward the outside in the radial direction in the middle of the thickness of the washer body (1b). (12s) is an example in which the washer body (1b) is not opened in the vertical planes (1u, 1w). FIG. 19C is an example in which two washers of FIG. 19B are attached facing each other. When the thickness T of the washer body (1b) is thick, the second stress non-transmission space (12s) as shown in FIG. 19 (c) is provided near the nut (4) to provide the first meshing thread. The thread load sharing ratio can be reduced. Further, in this example, the upper and lower planes of the washer are the same, so that there is no misuse during use.
-Fig. 19 (d) shows a shape that takes into consideration the centering of the washer (1), and shows a method of increasing the length t of the inner peripheral surface of the bolt hole (see the shape on the bolt hole side) and the nut side on the outer peripheral side. A modified example of a method (see the protrusions on the outer peripheral side of the washer body (1b)) in which a ring shape or several protrusions are provided on the bolt and the outer peripheral portion of the nut is used to align the center with the bolt is shown. ..
FIG. 20 has a curve or a straight line at the rising portion (Br) on both sides of the corner portion (Bc) and the inner peripheral end portion (Be) of the bolt hole, and the middle of the curve or the straight line, that is, the corner portion (Bc) is a straight line. This is an example. In the example of FIG. 20, the rising portion (Br) and the inner peripheral end portion (Be) of the bolt hole are also straight lines, and only the connecting portion of each line is connected by the stress concentration relaxation curve.

(chamfer)
In the present invention, the washer body (1b) is formed with a stress non-transmission space (1s) so as to be connected to the upper plane (1u), lower plane (1w), and bolt hole inner peripheral surface (1i) of the washer body (1b). When the connection point is configured as part of the stress concentration relaxation curve in the cross section, chamfering is basically unnecessary, but depending on the shape of the stress non-transmission space (1s), it may be particularly arc-shaped or elliptical arc-shaped. It may be chamfered. The position Ph on the inner peripheral surface (1i) side of the bolt hole of the washer body (1b) in the first stress non-transmission space (11s) may be configured as a part of the stress concentration relaxation curve, or a part of the stress concentration relaxation curve. Although not, it may be chamfered arbitrarily. The position P3 on the lower plane (1w) of the washer body (1b) in the second stress non-transmission space (12s) or the position P2 on the inner peripheral surface (1i) side of the bolt hole may be configured as a part of the stress concentration relaxation curve. Although it is not a part of the stress concentration relaxation curve, it may be chamfered arbitrarily.

In the prior art, the corners of the bolt hole forming portion of the washer body may be chamfered. The chamfer in the prior art is often arcuate or triangular in vertical cross section, but its dimensions are fine, with a maximum screw pitch p of less than 0.35p, more than 0.5p, and more. Since it is not the same as the pitch p, it can be clearly distinguished from the stress non-transmission space (1s) of the present invention.

(Outer circumference of washer)
The outer peripheral dimension of the washer (1) is preferably the same as or slightly larger than the outer peripheral dimension of the nut (4). The outer peripheral dimension of the washer (1) can be considered as the diameter of the circle inscribed in the washer (1) in the plan view looking into the screw hole of the washer (1). In this sense, the outer peripheral dimension D of the washer (1) may be the same as the outer peripheral dimension of the washer (1) that is standardly used corresponding to the outer diameter of the bolt used in the first aspect of the present invention. In one embodiment, the outer peripheral dimension of the washer (1) may be 1.8 times or more the inner diameter of the washer (1) (or the outer diameter of the bolt), and is 1.9 times or more, 2 times or more, 2 times or more. . It may be 1 times or more, 2 times or more, 2 or 3 times or more. Further, the outer peripheral dimension D of the washer (1) may be 4 times or less, 3 times or less, and 2.5 times or less the inner diameter of the washer (1) (or the outer diameter of the bolt).

In another preferred embodiment, the outer peripheral dimension D of the washer (1) is (D / 2) ² -{(R4) / 2 + Ls} ² when the inner diameter (or the outer diameter of the bolt) of the washer (1) is R4. ≧ k {(R4) / 2} ² (in the equation, k = 2.5), and further, k = 2.7, k = 2.9, and k = 3.0. Further, the outer peripheral dimension D of the washer may be (D / 2) ² -{(R4) / 2 + Ls} ² ≤ q {(R4) / 2} ² (in the formula, q = 3.5), and further. May be q = 3.3, q = 3.1, q = 3.0.

(nut)
The outer peripheral dimension of the nut (4) can be considered as the diameter of a circle inscribed in the nut (screw shaft portion, or flange portion in the case of a flange nut) in a plan view looking into the screw hole of the nut (4). In this sense, the outer peripheral dimension D of the nut (4) is the same as the outer peripheral dimension of the nut (4) which is standardly used corresponding to the outer diameter of the bolt (3) used in the first aspect of the present invention. However, in one embodiment, the outer peripheral dimension of the nut (4) may be 1.8 times or more the inner diameter of the nut (4) (or the outer diameter of the bolt) 1.9 times or more and 2 times or more. As mentioned above, it may be 2.1 times or more, 2.2 times or more, and 2 or 3 times or more. Further, the outer peripheral dimension D of the nut (4) may be 4 times or less, 3 times or less, and 2.5 times or less the inner diameter of the nut (4) (or the outer diameter of the bolt).

Further, in one aspect of the aspect A, in the plan view of the fastening structure viewed from the axial direction, the contact surface between the upper plane (1u) of the washer (1) and the lower plane (4w) of the nut (4) is the axis. Assuming a circle inscribed in the contact surface centered on, the radius of the inscribed circle is twice the distance between the line (4e) connecting the roots of the threads of the nut (4) and the axis of the nut (4). It may have a dimension of 0.8 times or more, further 0.9 times or more, and 1.0 times or more the sum of the distance Ls and the distance Ls. Further, in one aspect of the aspect B in which the second stress non-transmission space (12s) is open to the lower plane (1w), the lower plane of the washer (1) in the plan view of the fastening structure viewed from the axial direction Assuming that the contact surface between 1w) and the object to be fastened (2) is a circle inscribed in the contact surface centered on the axis, the radius of the inscribed circle is the line connecting the valley bottoms of the threads of the nut (4) (4e). ) And twice the distance (radius) of the axis and 0.8 times or more the sum of the distance Ls, and further 0.9 times or more and 1.0 times or more.

The outer circumference of the washer body (1b) may be larger than the outer circumference of the upper plane (1u) in contact with the nut (4). In the vertical cross section, the washer body (1b) may be cut out at an elevation angle of, for example, 30 to 60 degrees, and further 40 to 50 degrees at the connection portion between the outermost circumference (1о) and the upper plane (1u). The size of the notch portion (1d) is the dimension in the thickness direction of the washer body (1b), and may be half or less, further one-third or less of the thickness T of the washer body (1b). The notch portion (1d) can have a shape corresponding to the flange portion of the flange nut.

In another preferred embodiment, the outer peripheral dimension D'of the nut (4) is (D' / 2) ² -{(R4) / 2 + Ls, where R4 is the inner diameter of the nut (4) (or the outer diameter of the bolt). } ² ≧ k {(R4) / 2} ² (in the equation, k = 2.5), and further, k = 2.7, k = 2.9, k = 3.0. Good. Further, the outer peripheral dimension D'of the nut may be (D'/2) ² -{(R4) / 2 + Ls} ² ≤ q {(R4) / 2} ² (q = 3.5 in the formula). Furthermore, q = 3.3, q = 3.1, and q = 3.0 may be obtained.

The nut (4) may be a polygonal nut without a flange portion (usually a hexagon nut), but a flange nut having a flange portion (4f) is preferable. The flange nut has a screw shaft portion and a flange portion (4f) widened from the screw shaft portion, and the bottom surface (seat surface) on the flange portion (4f) side is a flat surface. In the flange nut, it is preferable that the outer peripheral dimension D'of the bottom surface (seat surface) on the flange portion side has the above-mentioned dimension in order to secure a predetermined fastening area. On the other hand, the screw shaft portion of the flange nut can be smaller than the outer peripheral dimension D of the bottom surface (seat surface), and the material cost can be saved. The flange portion (4f) in the flange nut bears (increases) the required fastening area in order to secure the fastening force between the nut (4) and the washer (1), and has the required axial thickness. However, since the required (minimum) thickness in the axial direction is sufficient and the axial thickness portion on the screw opening side is not required, an elevation angle of about 70 degrees or less is preferable in the vertical cross section. Further, about 60 degrees or less, about 50 degrees or less, particularly about 45 degrees or less or about 40 degrees or less, more preferably about 20 degrees or more, and further about 30 degrees or more, about 35 degrees or more, particularly about 40 degrees or more elevation angle (tilt). The material of the screw shaft portion may be reduced as the shape having the portion). The fastening force between the washer (1) and the nut (4) is from the fastening surface of the washer (1) and the nut (4) to the nut (4) and near the outer circumference of the nut (4) (at a position far from the bolt hole). Compressive stress in the elevation angle direction of approximately 40 to 45 degrees or more toward the screw of the bolt (3) is important, and the stress transmission in the portion with a smaller elevation angle is not directed to the screw of the nut (4) or the force is small. In some cases, such a portion of the nut (4) may be absent and therefore an inclined portion and a screw shaft portion of the flange nut (see FIG. 3). Further, in the vertical cross section, the vicinity of the outer peripheral surface of the flange portion of the flange nut may be substantially perpendicular to the seat surface for strength reinforcement, and the thickness of that portion is, for example, 0.5 p with respect to the screw pitch p. It may be 1p or more, 1.5p or more, 2p or more, 3p or more, 20p or less, 10p or less, and further 5p or less. It is desirable that the outer peripheral surface of the connecting portion between the nut shaft portion (4s) and the flange portion (4f) is connected by a stress concentration relaxation line. The outer diameter of the screw shaft portion is preferably a standard dimension corresponding to the screw hole diameter of the nut, and the outer diameter of the bearing surface of the flange portion is the radial dimension (Ls) of the stress non-transmission space (1s). Correspondingly, it is preferable to expand the outer diameter of the screw shaft portion, and the enlarged dimension is preferably 0.7 times or more the radial dimension (Ls) of the stress non-transmission space (1s), 0.8. It may be double or more, 0.9 times or more, 1.0 times or more, preferably 1.3 times or less, and may be 1.2 times or less, 1.1 times or less, 1.0 times or less. Further, the axial (maximum) dimension of the flange portion, that is, the dimension from the start point at which the radial dimension of the flange portion expands to the nut bearing surface is the radial dimension (Ls) of the stress non-transmission space (1s). It is preferable to correspond, and the dimension is preferably 0.5 times or more, 0.7 times or more, 0.8 times or more, 0.9 times the radial dimension (Ls) of the stress non-transmission space (1s). It may be double or more, 1.0 times or more, preferably 1.3 times or less, and may be 1.2 times or less, 1.1 times or less, 1.0 times or less.

In one embodiment, when the washer (1) is aspect B, the outer peripheral inclined portion of the flange portion (4f) of the nut (4) is the second stress non-transmission space (12s) of the washer (1) in the vertical cross section. Corresponding to the corner portion (Bc), the shortest distance between the outer peripheral inclined portion of the flange portion (4f) and the corner portion (Bc) of the washer (1) is the radial dimension of the screw shaft portion (the outer peripheral dimension of the screw shaft portion). The difference between the screw and the inner diameter of the screw) is substantially the same, for example, 0.8 to 1.2 times and 0.9 to 1.1 times.

The surface (seat surface) of the nut (4) on the washer (1) side may be a flat surface. The nut (4) having a flat seat surface is preferable because it is easily available and manufactured. However, it is not necessary, but at the time of fastening, on the washer (1) side surface (seat surface 4w) of the nut, on the upper side (nut side) of the stress non-transmission space of the washer (1), the screw shaft portion As long as it retains the strength of (4s) and does not need to transmit the fastening force, it may be formed as a space (recess). Further, even when the above space exists, the nut (4) comes into contact with the washer (1) on the flat surface on the washer (1) side, and the threaded portion of the nut (4) (including the first screw thread). ) Is not located below the washer (1) side flat surface (washer side).

Further, the nut (4) does not need to form a notch or a recess (space) with respect to the normal shape, and when the nut (4) is a flange nut, the flange portion (4f) and the screw shaft portion (4s) In any of the above cases, it is not necessary to form a notch or recess (space) with respect to the normal shape of the nut (4), and it is preferable that there is no such notch or recess (space). Notches or recesses (spaces) may impair the strength of the nut. Here, the normal shape of the nut (4) is that if the screw shaft portion main body (polygonal portion including the screw shaft portion), the distance from the bolt hole (1h) to the outer periphery of the screw shaft portion main body is in the axial direction. It means that there is no notch or gap in the meat part, and if it is the flange part (4f), the distance from the bolt hole (1h) to the outer circumference of the screw shaft part main body is the corresponding distance of the screw shaft part main body. Expands in the axial direction to reach the seating surface (as described above, the distance from the bolt hole (1h) to the outer periphery of the screw shaft portion main body may be constant in the vicinity of the seating surface), and extra meat is added to the meat portion. It means that there is no notch or void.

[Second aspect of the present invention]
According to the second aspect of the present invention, a washer body (1b) having parallel first and second planes (1u, 1w) and the first and second planes (1b) penetrating the washer body (1b). A washer (1) having a bolt hole (1h) extending in a direction perpendicular to 1u and 1w), wherein the washer (1) has an axis (z) and an axial direction of the bolt hole (1h). , Has a radial direction (r) perpendicular to the axis (z),
The washer body (1b) has a stress non-transmission space (1s) that opens into the bolt hole (1h) and extends in the radial direction in a vertical cross section including the axis of the washer (1).
A washer (1) is provided in which the stress non-transmission space (1s) is a concentric annular shape centered on the axis (z) of the bolt hole (1h).
Hereinafter, the second aspect of the present invention will be described without limitation using preferred embodiments and drawings.

The second aspect of the present invention is an invention having an application development aspect of the first aspect, and the matters described in the first aspect can be applied as they are or modified to be applied to the second aspect. , Also adapts to the second aspect. Therefore, in particular, it is understood that the matters described about the washer in the first aspect and the matters concerning the relationship between the washer and the washer fastening structure also apply to the second aspect without any particular notice. Should be. On the contrary, it is understood that the matters described about the washer in the second aspect and the matters concerning the relationship between the washer and the washer fastening structure can be applied to the first aspect without any particular notice. Should be.

1 and 5 show an example of a structure in which the object to be fastened (2) is fastened to the substrate (5) using a bolt (3), a nut (4), and a washer (1) as a vertical sectional view thereof. , FIG. 1 is an example of the prior art, and FIG. 5 is an example of a fastening structure using the washer of the present invention. When fastening the object to be fastened (2) to the substrate (5) with the bolt (3), the nut (4) and the washer (1), the washer (1) is placed between the object to be fastened (2) and the nut (4). By interposing the washer (1) having an area larger than the fastening surface of the nut (4), the fastening of the object to be fastened (2) by the nut (4) can be stabilized. In the present invention, the fastening direction of the bolt (3), the nut (4), the washer (1), the object to be fastened (2) and the substrate (5) is the axial direction of the bolt (3), and the fastening structure and the bolt ( 3), the axial direction common to the nut (4) and the washer (1). The direction perpendicular to the axial direction is called the radial direction. For the nut (4) and washer (1), the radial bolt side (bolt hole side) is referred to as the inside, and the direction away from the bolt side is referred to as the outside.

Bolt-nut fastening is performed by tightening the female screw formed on the nut (4) against the male screw formed on the bolt (3). Therefore, basically, the screw of the bolt (3) is fastened. From the nut (4) to the washer (in the direction perpendicular to the contact surface between the nut (4) and the washer (1) and the contact surface between the washer (1) and the object to be fastened (2)) of the bolt (3). A tensile stress acts toward the side of 1) (see FIG. 2). At the same time, when the nut (4) is tightened against the bolt (3), a compressive stress acts on the screw of the nut (4) between the contact surface of the nut (4) and the washer (1). Since the compressive stress acts between the position radially away from the screw axis of the washer (1) and the screw of the nut (4), it acts in a direction inclined with respect to the screw axis (see FIG. 3). In FIGS. 2 and 3, the intensity is represented by the vector density and length as well as the direction of the field line. The compressive stress acts on the screw of the bolt (3) as a reaction force of the compressive stress acting on the screw of the nut (4). Therefore, a stress obtained by combining the above tensile stress and compressive stress acts on the screw of the bolt (3) (see FIG. 4). In FIG. 4, * indicates a place that is easily destroyed.

In this fastening structure, as described above, there is a problem that the crack shaft breakage easily occurs due to the fatigue of the first thread of the fastening mesh of the bolt (3) (* position in FIG. 4). 2 and 3 show the results of actual evaluation by the present inventor of the tensile stress and the compressive stress acting on the bolt (3) and the nut (4) in the example of the fastening structure of the prior art, in the direction of the vector and in FIG. It is a figure which shows as an intensity (the density and length of a vector). Fastening and meshing of the bolt (3) with respect to the screw of the bolt (3) From the low-order mountain side to the high-order mountain side, the 1st, 2nd, 3rd, 4th ... The stress applied sequentially becomes smaller, and the maximum stress is applied to the first mountain. FIG. 4 shows the result of synthesizing the tensile stress and the compressive stress of FIGS. 2 and 3, and shows the magnitude of the stress vector in grayscale (white represents the largest force). The direction of stress can be understood by the position and orientation of the white part. The first thread (mountain peak) and the second thread (mountain peak) of the bolt (3) are fastened and meshed with the screw of the nut (4).・・ Corresponds to each. The numerical value of the load sharing rate with nuts (the load sharing rate of bolts is also supported) is 35.6% for the first thread of fastening meshing, 20.6% for the second thread, 14.5% for the third thread, and 4 The threads are 11.0%, 5th 8.5%, 6th 5.9%, 7th 3.9%, and sharply toward the open side (higher-order side) 4o of the thread. It was confirmed that the load sharing was reduced.

Therefore, the stress (tensile stress and compressive stress) applied to each thread by fastening is moved to the higher-order thread side (upward in FIGS. 1 to 4 and fastening force release side) 4о as compared with the conventional product, and fastened. It is considered that if the stress applied to the first and second threads of the bolt (3), especially the first thread, can be reduced, the fatigue failure of the bolt (3) can be reduced and the fatigue life can be extended. ..

The washer (1) on the second aspect of the present invention is a washer having a structure that enables this. FIG. 5 is a view showing a vertical cross section including an example bolt hole (1h) of the washer (1) on the second side surface of the present invention. In the vertical cross section, the washer body (1) of the washer (1) A stress non-transmission space (1s) is provided on the object to be fastened (2) side and the bolt hole (1h) side of 1b). This stress non-transmission space (1s) has a concentric annular shape centered on the axis of the bolt hole (1h). Since the fastening force is not propagated in the stress non-transmission space (1s) in the washer body (1b), the compressive stress from the contact surface between the washer (1) and the object to be fastened (2) is the stress non-transmission space (1s). It acts between the contact surface between the washer (1) and the object to be fastened (2) and the screw of the nut (4) and the bolt (3) only in the portion where 1s) does not exist. A part of the stress propagated in the axial direction (upper direction in the figure) of the bolt (3) in the portion where there is no stress non-transmission space (1s) is deflected toward the bolt (3) above the stress non-transmission space (1s). Although it is (diffused), there is a limit to the angle at which the stress is deflected (diffused). Compared to the case without 1s), as a result of moving the bolt (3) to the higher-order mountain valley bottom side, the stress applied to the bolt (3) fastening mesh lower-order mountain valley bottom side can be reduced. It is possible.

The stress non-transmission space shown in FIG. 5 is an example (an example of aspect A) of the stress non-transmission space of the washer (1) on the second side surface of the present invention, and the washer (1) of the present invention has this structure. Not limited. The stress non-transmission space (1s) is a space that opens in the bolt hole (1h) and extends in the radial direction in the vertical cross section including the axis of the washer (1), and is centered on the axis of the bolt hole (1h). It may be a concentric ring.

(Stress non-transmission space)
The stress non-transmission space (1s) is opened in the bolt hole (1h) in the vertical cross section of the washer (1). Since the stress non-transmission space (1s) is opened in the bolt hole (1h), the axial transmission of the fastening force on the bolt hole (1h) side of the washer (1) is blocked, so that the stress non-transmission space is blocked. Since only the fastening force from the outer peripheral side of (1s) is transmitted to the bolt hole (1h) side and the fastening force has to wrap around from the outer peripheral side of the stress non-transmission space (1s), the bolt on the bolt hole (1h) side. The force applied to the lower-order mountain grain side of the fastening mesh of (3) is reduced.

The stress non-transmission space (1s) opens in the bolt hole (1h) in the vertical cross section of the washer (1), and further, the first plane (upper plane) (1u) on the nut (4) side of the washer body (1b). ), Or the second plane (lower plane) (1w) of the washer body (1b) on the object to be fastened (2) side, or the washer body (1w). The shape may not be open to either the first plane (upper plane) (1u) or the second plane (lower plane) (1w) of 1b). 5 to 7 are examples of the washer body (1b) opening on the first plane (upper plane) (1u) side. At least one stress non-transmission space, since the washer body (1b) must partially extend to the bolt hole (1h) for alignment (centering) to allow bolt alignment. (1s) is usually the first plane (upper plane) (1u) and the second plane of the washer body (1b) in the vertical cross section including the portion extending to the bolt hole (1h) of the washer (1). (Bottom plane) A shape that does not open to one or both of (1w). In the second aspect of the present invention, either the first plane (1u) or the second plane (1w) of the washer (1) can be on the top, but in the bolt / nut fastening structure, the nut side is on the top. Since it is convenient to think about it, the first plane will be referred to as an upper plane (1u) and the second plane will be referred to as a lower plane (1w) for convenience of explanation. The washer (1) on the second side surface of the present invention can satisfy the requirements of the washer (1) on the second side surface of the present invention when one of the two planes is the first plane (upper plane). Just do it.

The stress non-transmission space (1s) is different from the conventional chamfering and deburring, at least in terms of purpose and dimensions, and in most cases in shape. In particular, chamfering and deburring of corners on the surface of the washer body (1b) in contact with the bolt hole (1h) should be done in the axial direction to prevent interference such as the bolt neck R riding on the bolt (3) when it is placed under the neck. It is necessary to have the same dimensions in the radial direction, and when C or R is chamfered and brought into contact with the nut (4), unnecessary protrusions (not to damage the nut seat surface or the surface of the object to be fastened) For the purpose of removing burrs), the corners are ground or cut to the minimum allowable size, and the chamfering and deburring dimensions are made as small as possible as long as the purpose is achieved. Its dimensions are about 5% or less of the thickness T of the washer body 1b, particularly 4% or less, or 5% or less of the diameter of the bolt hole 1h, particularly 4% or less. Specific dimensions are less than 0.5 mm when the bolt hole diameter is 13 mm, less than 0.5 mm when the bolt hole diameter is 21 mm, and less than 1 mm when the bolt hole diameter is 36 mm in the radial direction of the bolt hole (1h). Degree. In most cases, the chamfering or deburring shape is either cut with a straight line having an inclined corner or the corner is made into an arc shape in the vertical cross section of the washer (1) (axis line at the corner). Same shape in direction and radius). On the other hand, the stress non-transmission space (1s) in the present invention cuts off the transmission of the fastening force between the bolt and the nut, and reduces the stress applied to the lower-order chamfer side of the bolt fastening engagement. Since it is intended, the dimensions for that purpose are substantially different (larger dimensions) from chamfering and deburring. Also, the shape of the stress non-transmission space (1s) is usually substantially different from chamfering and deburring. In many cases, the shape of the stress non-transmission space 1s is not the same shape in the axial direction and the radial direction at the corners like chamfering, but is a shape having a larger radial dimension than the axial direction. It is clear that the stress non-transmission space of the present invention is different from chamfering and deburring when looking at its shape and dimensions. The washer (1) of the present invention has a function of "not damaging the mating surface (nut seat surface, surface of the object to be fastened), and avoiding interference with the bolt neck R when the bolt (3) is inserted" required for the conventional washer. Can be designed and manufactured with.

The stress non-transmission space (1s) is a concentric ring centered on the axis of the bolt hole (1h). The stress non-transmission space (1s) is, for example, a three-dimensional space (concentric annular space) formed by rotating a space (1s) having a cross-sectional shape as shown in FIG. 5 by 360 degrees about an axis. The concentric annular space may be displaced or fluctuated in shape (for example, axial dimension) within a range that does not impair the effect of the present invention. Even if there is displacement or fluctuation, the range or average value may be within the range defined by the present invention. In the plan view of the upper plane of the washer (1), the washer body (1b) extends to the bolt hole (1h) may be a part of the washer body (1b). In that case, the washer body (1b) The space formed by the portion where 1b) does not extend to the bolt hole (1h) can be continuous with the concentric annular stress non-transmission space. The space continuous with the stress non-transmission space is a portion that does not transmit stress, but is not the stress non-transmission space (concentric annular space) defined in the present invention.

As described above, the fastening force basically acts in the axial direction, but the compressive stress from the contact surface of the washer (1) with the object to be fastened (2) is transmitted inside the nut (4) and is transmitted from the axial direction. It can be transmitted to the screw of the bolt (3) with a constant spread (inclination), and can wrap around from the outside of the stress non-transmission space (1s) to the bolt hole (1h) side. When the washer (1) of the present invention is used, the compressive stress between the washer (1) and the object to be fastened (2) is limited to the outside of the stress non-transmission space (1s) due to the presence of the stress non-transmission space (1s). (As a result, it moves outward in the radial direction), and its compressive stress has no choice but to wrap around from the outside of the stress non-transmission space (1s) to the bolt hole side, and the wraparound compressive stress extends to the bolt hole side. The maximum angle is about 45 degrees from the end far from the bolt hole (1h) in space (1s). Even if the compressive stress between the nut (4) and washer (1) wraps around from the outside of the stress non-transmission space (1s) at a maximum angle of 45 degrees and is not transmitted to the lower thread of the screw, the bolt (3) ) And the nut (4) are basically the tensile stress of the bolt screw and the shaft, and the lower the thread is, the larger the fastening stress is. Therefore, these two fastening stresses (tensile stress and compressive stress) are used. The combined force is still greater for the lower threads of the screw. However, when the stress non-transmission space 1s exists, the compressive stress applied to the low-order thread of the screw becomes smaller than that in the case where the stress non-transmission space (1s) does not exist, and as a result, the stress applied to the low-order thread of the screw becomes smaller. Becomes smaller. Further, the larger the radial dimension of the stress non-transmission space (1s) is, the smaller the compressive stress applied to the lower thread of the screw can be reduced. Therefore, the tensile stress and the compressive stress applied to the lower thread of the screw The combined stress is smaller. If the radial dimension of the stress non-transmission space (1s) is set to an appropriate dimension or less, the stress applied to the low-order thread of the bolt can be reduced, and the outer diameter of the nut and washer does not need to be increased too much. preferable.

In the washer on the second side surface of the present invention, the radial dimension of the stress non-transmission space (1s) is from the position Ps, where Ps is the position farthest from the bolt hole (1h) of the stress non-transmission space (1s). , The distance L in the radial direction to the inner peripheral surface (1i) of the bolt hole parallel to the axis z or its extension line can be defined.

With reference to the vertical cross-sectional views of FIGS. 5 to 7, the washer (1) has a stress non-transmission space (11s) opened on the bolt hole (1h) side and the upper plane (1u) side of the washer body (1b). Can be done. In the first stress non-transmission space (11s), the position Ps farthest from the bolt hole (1h) in the first stress non-transmission space (11s), and in FIGS. 5 to 7, the first stress non-transmission space (11s) is the washer body (11s). The distance in the radial direction from the position Pt in contact with the upper plane (1u) of 1b) to the extension line of the inner peripheral surface (1i) of the bolt hole parallel to the axis is defined as L.

With reference to the vertical sectional views of FIGS. 13 to 14, the washer (1) has a second stress non-transmission space (12s) opened on the bolt hole (1h) side and the lower plane (1w) side of the washer body (1b). Can have. At the fourth boundary line (B4) of the washer body (1b) and the second stress non-transmission space (12s), in the radial direction from the bolt hole of the second stress non-transmission space (12s) of the fourth boundary line (B4). The farthest position Ps, in FIGS. 13 to 14, from the position P3 where the second stress non-transmission space (12s) is in contact with the lower plane (1w) of the washer body (1b), the inner peripheral surface (1i) of the bolt hole parallel to the axis or its The radial distance to the extension line is defined as L.

The washer (1) on the second side surface of the present invention is, in one preferred embodiment, when the stress non-transmission space (1s) has the position Ps farthest in the radial direction from the axis z in the vertical cross section of the washer (1). , The radial distance L from the position Ps to the inner peripheral surface (1i) parallel to the axis of the bolt hole 1h or its extension line is
0.5p ≦ L ≦ 5.7p, more preferably 0.8p ≦ L ≦ 5.6p, 1.0p ≦ L ≦ 5.0p, still more preferably 1.5p ≦ L ≦ 4.5p, especially 2.0p ≦ L ≦ 4.0p, and further 2.5p ≦ L ≦ 3.5p
(In the formula, the diameter of the bolt hole (1h) is R, and the units of R and p are mm.
When R is 1.9 or less, p is 0.2 and
When R is more than 1.9 and less than 2.4, p is 0.25.
When R is more than 2.4 and 3.7 or less, p is 0.35.
When R is more than 3.7 and 5.5 or less, p is 0.5.
When R is more than 5.5 and 7.5 or less, p is 0.75.
When R is more than 7.5 and 9.5 or less, p is 1.0.
When R is more than 9.5 and 13 or less, p is 1.25.
When R is more than 13 and 23 or less, p is 1.5.
When R is more than 23 and less than 34, p is 2.
When R is more than 34 and less than 40, p is 3.
When R is more than 40 and 150 or less, p is 4. )
Meet. This aspect is advantageous when the washer is combined with bolts and nuts having fine or coarse threads, and especially when combined with bolts and nuts having fine threads. For bolts and nuts, fine screws are preferably used for precision structural applications, and the problem of durability is more serious with fine screws, so improvement of the fastening structure when using fine screws is more sought after. Therefore, the effect of the washer in this embodiment is more remarkable when used together with the bolt and nut of the fine screw. However, the washer of this aspect is also effective when used with bolts and nuts of coarse threads, and may be effective even in the case of coarse threads.

Further, the washer (1) on the second aspect of the present invention can have an L in a range different from the above range in another preferred embodiment. For example, washers may be provided that are particularly advantageous when combined with coarse or coarse threaded bolts and nuts.

(Preferable stress non-transmission space)
FIG. 5 shows a washer (1) which is a preferable example in the second aspect of the present invention, and a vertical cross-sectional view of a washer fastening structure using the washer (1). (3) is a bolt, (4) is a nut, (1) is a washer, (2) is an object to be fastened, and (5) is a substrate. The washer (1) has a washer body (1b) and a bolt hole (1h) that penetrates the washer body (1b) and has an axis. The washer (1) and the washer body (1b) have an axis and an axis direction z, and a radial direction r perpendicular to the axis z.

The washer body (1b) has two parallel planes, that is, an upper plane (1u) and a lower plane (1w), and an inner peripheral surface (1i) defining a bolt hole (1h) in the center and a bolt hole (1i). It has an outer peripheral surface (1о) that is radially outside from 1h). The bolt hole (1h) is a hole through which the bolt (3) is penetrated, and has a diameter R slightly larger than the bolt diameter according to the assumed bolt diameter. For example, the bolt hole diameter of a nut for a nominal M10 (thread diameter of 10 mm) may be 11 mm. The surface (inner peripheral surface) (1i) defining the diameter R of the bolt hole 1h is parallel to the axis in the vertical cross-sectional view including the axis as shown in FIG. The shape of the cross section of the bolt hole (1h) (shape in the plan view) is not limited, but is usually circular. In order to stably arrange the washer (1) with respect to the bolt (3) by penetrating the bolt through the bolt hole 1h, the bolt hole (1h) of the washer (1) has the outer diameter of the bolt (3). On the other hand, it is preferable that it has a predetermined size and is circular. However, it is preferable that the inner peripheral surface of the eaves portion 1p described later is composed of the inner peripheral surface (1i) of the bolt hole, but the inner peripheral surface (1i) of the eaves portion (1p) is a plan view (cross section). In the plan view), it is not necessary to exist on the entire circumference of the circular bolt hole (1h), and it is sufficient that two or more protrusions are formed so that the bolt (3) can be positioned. When having this protruding eaves portion (1p), the space between the protrusions in the plan view is not a bolt hole in the second side surface of the present invention. In the plan view, the space between the bolt hole and its protrusion is continuous. Considering the space between the protrusions as a bolt hole, the planar shape of the bolt hole is not circular, but in such a case, the bolt hole is a virtual circular hole, and the washer body 1b has a virtual shape. Only the inner peripheral surface (1i) constituting the circular hole of the bolt hole is considered as the inner peripheral surface (1i) of the bolt hole.

In the vertical cross-sectional views of FIGS. 5 to 7, the washer body (1b) has a stress non-transmission space (1s), and the stress non-transmission space (1s) is opened in a bolt hole (1h). The stress non-transmission space (1s) is a space having a cross-sectional shape shown in FIGS. 6 and 7 (a), three-dimensionally, about the axis of the bolt hole (1h) of the washer (1) in the vertical cross-sectional view. Is a three-dimensional space (concentric ring) formed by rotating 360 degrees (see FIGS. 7 (b) and 7 (c)). Since the stress non-transmission space (1s) is opened in the bolt hole (1h), the axial transmission of the fastening force on the bolt hole side of the washer body (1b) is blocked, so that the bolt on the bolt hole side The force applied to the lower ridges is reduced.

When the washer (1) on the second side surface of the present invention is used together with the nut (4), the compressive stress applied to the screw of the bolt (3) from the contact surface between the washer (1) and the nut (4) is a stress non-transmission space. Due to the presence of (1s), it is limited to the outer peripheral side of the stress non-transmission space (1s) and wraps around the bolt hole (1h) from the outer peripheral side of the stress non-transmission space (1s), but the compressive stress extends to the bolt hole side. The maximum direction is an elevation angle (angle θ) of approximately 45 degrees with respect to the axis z from the position Ps, which is the end far from the bolt hole (1h) in the stress non-transmission space (1s). The compressive stress transmitted to the bolt hole side at an angle of about 45 degrees or less with respect to the axis z depends on the size of the radial dimension L of the stress non-transmission space 1s, and the higher-order peaks (particularly the peaks) of the bolts. ), That is, it goes to the open side, and it is possible to reduce the load sharing ratio of the low-order thread of the bolt, especially the first thread. Further, when the radial dimension L of the stress non-transmission space (1s) is set to an appropriate dimension or less, the stress applied to the low-order thread is sufficiently reduced, and the outer diameter of the nut and washer is kept small. It is preferable because it can be used.

The distance L of the stress non-transmission space (1s) is 0.5p or more based on the value of p defined above. For example, 0.6p or more, 0.7p or more, 0.8p or more, 1. It may be 0p or more, 1.2p or more, 2.0p or more, 2.5p or more, 3p or more, and may be 5.7 or less, but for example, 5.0p or less, 4.0p or less, 3.5p or less. 0.6p ≦ L ≦ 5.6p, more preferably 0.8p ≦ L ≦ 5.6p, 1.0p ≦ L ≦ 5.0p, still more preferably 1.5p ≦ L ≦ 4.5p. In particular, it is preferable to satisfy 2.0p ≦ L ≦ 4.0p and further 2.5p ≦ L ≦ 3.5p.

(Stress non-transmission space of aspect A; first stress non-transmission space)
FIG. 5 shows a washer (1) which is a preferable example of the aspect A in the second aspect of the present invention, and a vertical sectional view of a washer fastening structure using the washer (1). (3) is a bolt, (4) is a nut, (1) is a washer, (2) is an object to be fastened, and (5) is a substrate. The washer (1) has a washer body (1b) and a bolt hole (1h) that penetrates the washer body (1b) and has an axis. The washer (1) and the washer body (1b) have an axis and an axis direction z, and a radial direction r perpendicular to the axis z.

In the vertical cross-sectional views of FIGS. 5 to 7, the washer body (1b) has a first stress non-transmission space (11s), and the first stress non-transmission space (11s) is opened in a bolt hole (1h). It is also open on the upper plane (1u). That is, the first stress non-transmission space (11s) is in contact with the extension line (B1) of the upper plane (1u) in the vertical sectional view and is below the extension line (B1). In the vertical sectional view, the third boundary line (B3) between the first stress non-transmission space (11s) and the washer body (1b) is a stress such as an arc or an elliptical arc convex upward from the position Pt on the upper plane (1u). The concentration relaxation curve extends to the position Ph of the inner peripheral surface (1i) (the surface defining the bolt hole (1h)) of the washer body (1b). Since the position Pt is on the upper plane (1u) of the washer body (1b) (the end of the upper plane (1u) and the boundary between the upper plane (1u) and the first stress non-transmission space (11s)), with line X of the elevation angle of 45 degrees with respect to the axis z is the position Ps in contact farthest from the bolt hole (1h) of the first stress non-transmitting space (11s), a straight line X is the washer body through the position P ₁ (1b) It is also the position Pt that intersects the upper plane (1u). In this case, the straight line X is said to "contact" the first stress non-transmission space (11s), but the straight line X is "the farthest position" from the bolt hole (1h) that "intersects" the first stress non-transmission space (11s). Means.

The first stress non-transmission space (11s) has a cross-sectional shape in contact with the upper plane (1u) (or an extension line thereof) of the washer body (1b) and below it in the vertical cross-sectional view, but three-dimensionally. Is a three-dimensional space (concentric annular shape) formed by rotating the cross-sectional space shown in FIGS. 6 and 7 (a) by 360 degrees around the axis of the bolt hole (1h) of the washer (1). ) (See FIGS. 7 (b) and 7 (c)).

With reference to FIGS. 5 to 7, the first stress non-transmission space (11s) is opened in the bolt hole (1h) in the vertical cross-sectional view of the washer (1). Since the first stress non-transmission space (11s) is opened in the bolt hole (1h), the axial transmission of the fastening force on the bolt hole side of the washer body (1b) is blocked, so that the bolt hole side The force applied to the lower ridges of the fastening mesh of a certain bolt is reduced.

When the washer on the second side surface of the present invention is used together with the nut, the compressive stress applied to the screw of the bolt (3) from the contact surface between the washer (1) and the nut (4) is in the first stress non-transmission space (11s). Due to the presence, it is limited to the outer peripheral side of the first stress non-transmission space (11s) and wraps around the bolt hole (1h) from the outer peripheral side of the first stress non-transmission space (11s), but the compressive stress extends to the bolt hole side. The maximum direction is an elevation angle (angle θ) of approximately 45 degrees with respect to the axis z from the position Ps, which is the end far from the bolt hole in the first stress non-transmission space (11s). The compressive stress transmitted to the bolt hole side at an angle of about 45 degrees or less with respect to the axis z is a higher-order mountain of the bolt according to the magnitude of the radial dimension L of the first stress non-transmission space (11s). It is possible to reduce the load sharing ratio of the lower thread of the bolt, especially the first thread, by moving toward the grain (especially the peak), that is, the open side. Further, when the radial dimension L of the first stress non-transmission space (11s) is set to an appropriate dimension or less, the stress applied to the low-order thread is sufficiently reduced, and the outer diameter of the nut and washer is reduced. It is preferable because it can be suppressed.

In one embodiment, the distance L of the first stress non-transmission space (11s) is
0.6p ≦ L ≦ 5.6p, more preferably 0.8p ≦ L ≦ 5.6p, 1.0p ≦ L ≦ 5.0p, still more preferably 1.5p ≦ L ≦ 4.5p, especially 2. 0p ≦ L ≦ 4.0p, and further 2.5p ≦ L ≦ 3.5p
(In the formula, the radius of the bolt hole is R, the unit of R and p is mm, and R and p have the above-mentioned relationship.)
It is preferable to satisfy.

The end of the washer body (1b) on the bolt hole (1h) side constitutes an inner peripheral surface (1i) at which the end of the washer body (1b) faces the bolt hole (1h), and the bolt (3) is centered. The thickness of the end portion (lower side of the first stress non-transmission space (11s)) of the washer body (1b) may be reduced so as to enable the above. The end of the washer body (1b) (the axial dimension of the inner peripheral surface (1i) may be 1 to 99% of the thickness T of the washer body (1b). For example, the end of the washer body (1b). The minimum axial dimension (thickness) Th of the portion (inner peripheral surface (1i)) is preferably 0.1 times or more and 0.7 times or less the thickness T of the washer, and more preferably, Th is. 0.2T ≦ Th ≦ 0.6T, and more preferably 0.22T ≦ Th ≦ 0.5T.

In the vertical sectional view of the washer, the third boundary line (B3) of the washer body (1b) and the first stress non-transmission space (11s) is composed of a curved line or a combination of a curved line and a straight line, and is composed of a stress concentration relaxation curve without corners. It is preferably composed, and particularly preferably composed only of curves. Further, the connection point between the upper plane (1u) of the washer body (1b) and the third boundary line (B3) of the first stress non-transmission space (11s) is a place where stress for fastening is likely to be concentrated. It is particularly preferable that the stress concentration relaxation curve has no corners. On the other hand, the stress concentration relaxation curve is not necessarily large at the connection point between the inner peripheral surface (1i) of the bolt hole of the washer body (1b) and the third boundary line (B3) of the first stress non-transmission space (11s). It does not have to be configured as.

(Mises equivalent stress distribution)
In one preferred embodiment, the washer of aspect A of the second aspect of the present invention is the third boundary line between the washer body (1b) and the first stress non-transmission space (11s) in the longitudinal section of the washer (1). In (B3), assuming that the washer body (1b) does not have the first stress non-transmission space (11s), the fastening force by the virtual nut is applied to the upper plane (1u) of the washer body (1b). In the stress distribution equivalent to Mieses formed on the washer body (1b) when is added, the lower plane (1u) is perpendicular to the upper plane (1u) from the position Pt in contact with the first stress non-transmission space (11s). It is preferable that the stress distribution curve of the Mieses equivalent stress value at a predetermined ratio with respect to the reference is on the bolt hole 1h side with respect to the Mieses equivalent stress value applied in the direction. This predetermined ratio may be 95%. Further, the predetermined ratio may be, for example, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, or 5%. It is particularly preferable that the predetermined ratio is 20%, 10%, or 5%.

All the axial forces of the bolts generated at the time of fastening mesh unevenly over the entire thread that is in contact with the nut, transfer the force equivalent to the axial force to the nut, and the sum of the forces that are unevenly shared by the nut threads is the nut. It becomes a stress that compresses the entire contact surface with the washer through the inside of. The total bolt axial force is equal to the total stress received on the entire surface of the washer. FIG. 13 shows one vertical cross section. For example, the analysis of FIGS. 8 and 11 is performed at 1/360 degree, which is consistent with the sum of 360 degrees. In addition, the stress applied to the washer (1) is never even, and is concentrated on the bolt hole side (inner circumference side of the nut) or at a considerably large rate (from various simulation results). The load sharing on the outer peripheral side of the nut (4) and washer (1) is small (there are many black parts in the simulation). Therefore, even if it is considered that the nuts and washers on the inner diameter side are concentrated on the contact point Pt, it is appropriate to analyze and design in consideration of the safer side.

With reference to FIG. 11, a fastening force is applied from the seat surface of the nut (4) to the contact surface (region on the outer diameter side of Pt) of the washer (1) at the time of fastening, and the nut seat is located at the position Pt of FIG. 11 (a). The compressive force F from the surface is vertically applied, and compressive stress is generated in the washer from the position Pt. At this time, it is assumed that the washer (1) is flat on both the upper and lower surfaces and has the same thickness on the entire surface, and the force applied to the washer is concentrated only on the position Pt. And the force F diffuses in the washer. In this way, when FEM analysis is performed on the state where the force is applied to the end of the bolt hole of the washer as described above, a large force acts in the direction of the force F, and at the same time, a stress diffused in the washer is generated. Here, since the Mises equivalent stress distribution (relative value) in the washer does not depend on the magnitude of the fastening force once the shapes of the washer and the nut are determined, the above assumption can be adopted. The Mises equivalent stress distribution depends on the material of the washer (Young's modulus and Poisson's ratio), but in a specific washer, it is determined by the Young's modulus, Poisson's ratio and shape.

An example of visualizing the Mises equivalent stress distribution under the above assumption is shown in FIG. 11 (b) with a black and white gradation. The maximum stress is directly below the position Pt, and the stress becomes weaker as the distance from the Pt increases. Further, in FIG. 11A, the flow of force is represented by a curved arrow schematically showing a force line. In FIG. 11A, six lines of 1 mb, 1 mc, 1 md, 1 me, 1 mf, and 1 mg are displayed from 1 ma in the center to the bolt hole side. The numbers are on one side only, but the stress distribution curves are contrasting on both sides. When arranged in descending order of stress, 1ma> 1mb> 1mc> 1md> 1me> 1mf> 1mg. 1 ma is a stress applied vertically downward from Pt, which is the maximum stress. The relative magnitude of the stress represented by 1ma, 1mb, 1mc, 1md, 1me, 1mf, and 1mg based on the magnitude of the stress of 1ma is determined regardless of the magnitude of the fastening force of the washer. It can be arbitrarily selected at regular intervals or at non-constant intervals. In this example, there are 7 levels from 1 ma to the outside of 1 mg. The black-and-white gradation of FIG. 11 (b) is displayed in nine stages, and does not directly correspond to the line of FIG. 11 (a). However, when looking at the region where the depth from the nut side plane of the washer is shallow, there may be a place where a line close to the line shown in FIG. 11A can be obtained. Since it is possible to obtain the Mises equivalent stress distribution, it is sufficient to display the stages according to the relative stress to be obtained. For example, the display of 5 steps, 7 steps, 8 steps, and 9 steps can be selected, and the strength difference of each step may be the same, or only the relative stress in the vicinity of Pt can be evaluated in small steps. It is possible. It is possible to know the Mises equivalent stress distribution curve to be obtained according to the application. Simply, based on the stress 1 ma applied vertically downward from the position Pt, in the region where the relative stress is greater than 95% to 90%, the third boundary line of the first fastening force non-transmission space (11s) (11s). It is preferable that B3) does not exist, and the relative stress line may be obtained from the Mises equivalent stress distribution.

In FIG. 11A, 1ma is a vertical line directly below the position Pt, is the line on the bolt hole side most in the upper plane (1u) of the washer (1), and is the maximum stress line. 1 mb to 1 mg are stress lines smaller than 1 ma in order. Since 1 mg is the smallest stress line and the stress on the bolt hole side is smaller than this, the effect of the fastening force on the strength of the washer can be ignored. Therefore, if the third boundary line (B3) of the first fastening force non-transmission space (11s) exists in the region (broken line shaded portion) on the bolt hole side from 1 mg, the first fastening force non-transmission space (11s) is formed. Even so, the effect of the force applied to the position Pt on the washer strength can be ignored. When the third boundary line (B3) is on the bolt hole side of the 95% stress distribution curve of the magnitude of the Mieses equivalent stress 1 ma applied directly under the position Pt, the 95% stress distribution curve is shown in FIG. 11 (a). Is a line that is almost vertical from the upper plane 1u to the lower plane 1w, for example, 1 mb, but in many cases, the third boundary line (B3) has a distance L / p = 0.5 to 5.7. Depending on the conditions, even if it follows a stress distribution curve such as 1 mb, it will bend somewhere along the way and extend to the bolt hole side. 1 mg is preferably, for example, 10%, particularly 5% of the stress at 1 ma. As can be understood from FIG. 11B, this relative stress has different magnitudes of stress at the upper part (near Pt) of the curved arrow and at the lower part (near the arrow of the arrow in the figure). The evaluation may be performed on the lower plane (1w) of the washer (that is, the surface in contact with the object to be fastened (2)).

In another aspect, the washer may be evaluated from the nut side plane to a specific depth. Black (large stress) to gray to white (small stress) in FIG. 11B shows such a stress distribution. Even when the force is diffused, it often spreads to about 45 degrees in the tangential direction. At that time, if the stress strength (1 ma) directly under Pt is compared with the stress strength (for example, 1 mc) on the bolt hole side, 1 ma is larger than that in black and gray in FIG. 11 (b). It is expressed by. It can be seen that the black and dark gray (high stress) regions in FIG. 11B show a decrease in stress toward the bottom of the position Pt, which means that the applied force is applied in the lateral direction (screw shaft) inside the washer. Since it is also diffused in the radial direction), the stress is displayed to be relatively small compared to the vicinity of Pt.

In the vertical cross section as shown in FIGS. 11A and 11B, the region where the third boundary line (B3) of the first fastening force non-transmission space (11s) should not exist is a bolt from the line 1ma directly below the position Pt. Although it is a small region on the hole side, the third boundary line (B3) of the first fastening force non-transmission space (11s) starting from the position Pt is, for example, larger than 0.01p and within 0.03p (p is defined earlier). It is important that the stress concentration relaxation curve is obtained in the vicinity of the position Pt up to the value obtained.). The stress concentration transition curve is, for example, an arc or an elliptical arc. If it is an arc, Pt is the apex, the center of the circle is directly below Pt, and if it is an elliptical arc, the Pt point is the apex of the minor axis of the ellipse. desirable. Further, the portion connected from the position Pt of the upper plane (1u) of the washer body (1b) to the third boundary line (B3) of the first fastening force non-transmission space (11s) is also one of the above arcs and ellipses. It is particularly desirable to construct it as a stress concentration relaxation curve for parts and other parts.

In the second aspect of the present invention, the fact that the third boundary line (B3) of the washer body (1b) is on the bolt hole (1h) side from the specific Mises equivalent stress distribution indicates that, for example, 1 mb, 1 mc of the curved arrow. It means that there is a third boundary line (B3) of the first stress non-transmission space (11s) only on the bolt hole side of any one of 1, 1md, 1me, 1mf, and 1mg. For example, when the most preferable specific Mises equivalent stress distribution is a line 1 mg (the stress line having a relative stress of 5% described above), the stress from the position Pt is on the region side on the right side of the third boundary line (B3). It is a region that has almost no effect, and the washer (1) does not deform or buckle even if a space is created.

In one embodiment, the range shown by the dashed diagonal line in FIG. 11A is a range that is not affected by the stress from the position Pt, and the region of the first stress non-transmission space (11s) can be set only in that range. preferable. However, since it may be used within the range of stress due to the component configuration, in that case, the vicinity of the position Pt starts with a stress concentration relaxation curve, resembling the shape of the curved arrow in FIG. 11 (a). On the more bolt hole side, the third boundary line (B3) has a shape that goes down to the lower plane side, but the third boundary line (B3) may be provided on the bolt hole side from 1 ma and may be provided on the outer peripheral side from 1 mg. Good. In FIG. 11, the third boundary line (B3) is on the bolt hole (1h) side from the position Pt and the stress distribution line equivalent to Mieses 1 mg, starts with an upwardly convex curve, and inflections in the middle and downwards. The position Ph is reached as a convex curve, but in particular, the portion connected from the position Pt on the upper plane (1u) of the washer body (1b) to the third boundary line (B3) is also configured as a stress concentration relaxation curve. There is. It may be on the bolt hole side from 1 ma, and more preferably on the bolt hole side of 1 mb, the bolt hole side of 1 mc, the bolt hole side of 1 md, the bolt hole side of 1 me, and the bolt hole side of 1 mf. It is particularly preferable that it is formed on the bolt hole side outside 1 mg. On the contrary, it is the conventional method of fastening that vertically cuts the stress distribution range at the strictest 1 ma, which is the state of the stress distribution in FIG. Therefore, the boundary line B3 should not be a vertical line such as 1 ma. The method of obtaining the Mises equivalent stress distribution is known as described above. The Mises equivalent stress changes depending on the magnitude of the fastening force, but the above relative stress magnitude distribution does not change.

The force from the nut corresponding to the stress distribution is applied to the range of the Mises equivalent stress distribution shown in FIG. 11, and the compressive stress is acting inside the washer. For example, assuming that the third boundary line (B3) of the washer leaves Pt and immediately enters the inside of the washer, and that it enters between the line 1 mb and the line 1 mc and has a line that goes down vertically as it is. , The third boundary line B3 passes through a place where there is a compressive force vector directed from Pt toward the bolt hole side. At this time, the part between the stress field lines 1 mb and 1 mc near Pt (the part that is lowered by about 5 degrees from Pt toward the bolt hole side when viewed from the center of the force line radius) faces the bolt hole side. The vector is working great. This vector continues to be given by the load F from Pt. When there is a third boundary line (B3) in this range, a force derived from the load F is applied from the inside of the washer (1) to the curve created by the third boundary line B3. When the stress distribution is examined with reference to FIG. 11B or the like, the stress magnitude is indicated on the third boundary line (B3). When this vector is in the washer toward the bolt hole side, when the external load fluctuation is repeatedly applied to the initial fastening load F entering from the nut, if the external load is excessive, the initial fastening load is working significantly. , The surface on the bolt hole side of the first stress non-transmission space (11s) composed of the third boundary line (B3) may be fatigue-broken and buckling may occur. Therefore, when the third boundary line (B3) enters the region where the internal stress is large, it is desirable to satisfy the usage conditions such as increasing the strength and rigidity of the washer.

Aspect A of the second aspect is, in one preferred embodiment, subject to a thickness limitation on the shape of the third boundary (B3) forming the first fastening force non-transmission space (11s) of the washer (1). There is. The restrictions are: i) Within a certain thickness T, the third boundary line (B3) has a surface on the bolt hole side that has a length that allows centering with the shaft of the bolt, except that the outermost part of the washer. Not required if a centering mechanism is provided in ii) The washer's first fastening force non-transmission space (11s) may be on one or both sides, iii) The washer's first fastening force non-transmission space (11s) The thickness of the washer member reduced by the depth is in the range of 1% to 99% of the washer thickness T. Iv) The point Pt in contact with the nut bearing surface starts from the reference point _Po and goes toward the outer periphery. It must be in the range of 0.5p or more and 6p or less (0.5p ≤ L ≤ 6p), v) The boundary line B3 that creates the first fastening force non-transmission space (11s) of the washer is stressed by the stress distribution equivalent to Mieses. Do not enter the range, vi) At position Pt, the boundary line B3 should be in contact with the nut seating surface with an edgeless stress concentration relaxation curve, vii) The contact between the nut seating surface and washer should be on the outer peripheral side of the position Pt as the boundary. It is preferable that the first fastening force non-transmission space 11s of the washer of the aspect A satisfies these conditions as much as possible. Here, the distance L between Pt and P ₀ is in the range of 0.5 p or more and 6 p or less (0.5 p ≦ L ≦ 6 p) toward the outer peripheral side starting from the reference point P ₀ , and is preferably 1 p ≦ L. It is in the range of ≦ 5p, and more preferably 2p ≦ L ≦ 4p.

(Modification example of aspect A of the first stress non-transmission space)
12 (a) to 12 (d) show a schematic view of a modified example of the first stress non-transmission space (11s).
FIG. 12A is an example in which only a part of the ellipse from the position Pt has a third boundary line (B3) reaching the position Ph.
In FIG. 12 (b), the first stress non-transmission space (11s) is located on both the upper and lower planes and has a vertically symmetrical shape. This is an example of a boundary line B3 that approaches the plane of the washer by a downwardly convex line, has an inflection point again, and reaches the position Ph by a horizontal straight line.
FIG. 12C is an example of a shape in which the first stress non-transmission space (11s) is located on both the upper and lower planes and reaches Ph by the third boundary line (B3) which is vertically asymmetrical.
・ FIG. 12D has a first stress non-transmission space (11s) only on the upper plane, starts with a part of an ellipse, enters a part of an arc in the opposite direction in the middle, and finally reaches the position Ph in a straight line. This is an example in which the first stress non-transmission space (11s) is formed by the boundary line (B3), and each line is connected by a curve.
In FIG. 12 (e), the position Ps farthest in the radial direction from the bolt hole (1h) in the first stress non-transmission space (11s) is the first stress non-transmission space (11s) in the upper plane (1u) of the washer. This is an example in which the position is farther from the bolt hole (1h) than the position Pt forming the boundary point with.

In FIG. 12, 1 m is a Mises equivalent stress distribution curve. According to the first stress non-transmission space (11s) created by such a third boundary line (B3), there is an advantage that the amount of deformation and wall thinning is reduced when the space (11s) is produced by cutting or pressing. There is. Further, in such a case, since the first stress non-transmission space (11s) can be set on both sides of the washer, there is an advantage that it is not necessary to distinguish the front and back when using the washer. Further, the washer of the aspect A is not limited to the modification shown in FIG. Since the washer is centered with the bolt, it is desirable that the axial dimension of the inner peripheral surface of the bolt hole is longer than p (p is a value defined above). The contact surface dimension of p or more is not limited to the dimension of one cross section, but may be a shape and a dimension for centering using a plurality of locations in the axial direction or the circumferential direction of the inner peripheral surface of the bolt hole. If the washer is centered with the bolt on the outer peripheral side of the washer, the bolt hole size indicates the Pt position and Mises stress distribution. If there is a third boundary line (B3) on the bolt hole side of the washer from at least 1 mb. Often, it is possible to widen the bolt holes of the washer and reduce the weight of the widened part.

When the first stress non-transmission space (11s) is provided on both sides of the washer (1) as shown in FIGS. 12 (b) and 12 (c), the contact surface of the nut (4) and the object to be fastened (2) come into contact with each other. The position Pt is often about the same distance on both sides, but in this case, the distribution of the stress equivalent to Mieses generated in the washer (1) is compressed because the spread from the nut bearing surface to the bolt hole side of the washer is small. It is desirable that the washer under stress has higher hardness and strength so as not to cause buckling. The choice of washer strength needs to be factored in at design time. In this case, the points where the object to be fastened (2) and the washer (1) are also formed so as to be in contact with each other at the tangent line of the stress concentration relaxation curve, and the corners are on the bolt hole side and the outer peripheral side so as not to cause unnecessary buckling. Regardless of, it is desirable to attach a part of the circle or ellipse of the stress concentration relaxation structure.

(FEM analysis result of washer of aspect A)
FIG. 8 shows the stress status shown by the Mises equivalent stress distribution by performing FEM analysis on the washer of aspect A with the same dimensional configuration as that of FIG. 4 (conventional washer). It can be seen that the white color (high stress) is diagonally present at the position Pt, the compressive stress is large, and the thread is oriented in the fourth direction. Light gray (slightly large stress) spreads, and flange nut screws are applied to the 2nd to 5th threads. Looking at the bolt side, white (high stress) is on the first and second threads of the bolt screw, but the area is small. Light gray is the third thread of the screw, and dark gray (slightly small stress) extends widely to the end of the bolt. In this way, stress spreads to many parts of the nut (4), and the bolts (3) and nuts (4) exert forces on many of the threads. Regarding the stress distribution of the washer (1), the stress is contained in the washer (1), and the black stress small portion is on the bolt (3) side and the outer peripheral side of the washer (1). No adverse effects such as bearing surface deformation occur at the contact portion corresponding to Pt.

9 shows the results obtained by FEM analysis when fastened with the washer structure of aspect A shown in FIG. 6 and when fastened with the washer having the conventional structure shown in FIG. 1, and the results obtained by FEM analysis are shown in FIG. 9A for each thread. The load sharing ratios are compared and shown in a list, and FIG. 9B shows the comparison of the load sharing ratios in a bar graph. The load sharing ratio at the first thread of fastening mesh is 35.6% in the case of the conventional structural washer, whereas it is absolutely 30.2% in the model of aspect A (example of FIG. 6). The value is reduced by 5.4 points, and the relative value is reduced by about 15%.

In aspect A, as L / p increases (equivalent to increasing L), the load sharing ratio of the first mesh thread tends to decrease. The reason is that there is a position Ps (position Pt in FIG. 8) at a distance L, and a force from a washer is applied to the nut bearing surface on the outer peripheral side thereof, and as shown in FIG. 8, diagonally to the upper right from the input position. This is because the force toward the thread of the nut increases and the stress increases after the third thread on the open side of the thread of the nut, so that the load sharing ratio entering the first thread decreases relatively. In FIG. 6, on the upper plane (1u) of the washer (1), Ls is the distance from the point at right angles to the axial extension line (4e) of the bottom of the nut screw valley to the position Ps (Pt). Further, the distance from the inner peripheral surface (1i) of the bolt hole of the washer (1) to the position Ps (Pt) is L. L is shorter than Ls by the length of the gap with the bolt hole. This gap length is the gap length of the bolt hole with respect to the bolt, and is typically 0.35 to 0.65 times the screw pitch p of the nut to be used, and is set to 0.4 p here. ..

The left figure of FIG. 10 shows the relationship between the change in the distance L (L / p) and the load sharing ratio of the first mountain of meshing in the aspect A of the first aspect of the present invention. The value of L / p on the horizontal axis is shown above the graph in the figure. In the example of the left figure of FIG. 10, Ls = L + 0.5 mm = L + 0.4p (L / p = (Ls / p) −0.4). The right figure of FIG. 10 summarizes the effects when the washer distance L of the aspect A is changed. The upper right figure of FIG. 10 is the Mises equivalent stress distribution diagram of the washer fastening of the conventional structure of FIG. 1, the middle right figure is the Mises equivalent stress distribution diagram of model 2 (L / p = 1.81), and the lower right figure is model 3 ( It is a Mises equivalent stress distribution diagram of L / p = 2.60). In model 2 and model 3, the shape of the first stress non-transmission space (11s) is the same in depth Lh from Po to Ph of the inner peripheral surface of the bolt hole (1i), and the distance Ls in model 3 is the same as that in model 2. Is a shape that is longer in the radial direction. With reference to these Mises equivalent stress distribution maps, it can be seen that the white part with high stress extends from the first thread to the higher-order thread side from the upper right figure to the middle right figure and the lower right figure. .. From these figures, when the load sharing ratio of the first thread of the bolt screw was obtained at each black spot position, it was 35.6% in the upper right figure, 30.2% in the middle right figure, and 29.1% in the lower right figure. It was shown that as the distance L or Ls increased, the load sharing ratio of the first thread of the screw decreased substantially linearly, and as the distance L increased, the load sharing ratio of the first thread of the bolt screw decreased from 35.6% to 29. It has decreased by about 18% to 1%. By reducing the load on the first thread, it is effective in improving the fatigue strength of the bolt meshing on the bottom of the first thread.

(Stress non-transmission space of aspect B; second stress non-transmission space)
FIGS. 13 to 15 show an example of the washer (1) of the second aspect aspect B of the present invention. It is a vertical cross-sectional view except for FIGS. 15 (b) and 15 (c). 15 (b) and 15 (c) are perspective views. The washer (1) has a washer body (1b) and a bolt hole (1h) that penetrates the washer body (1b) and has an axis. The washer (1) and the washer body (1b) have an axis and an axis direction z, and a radial direction r perpendicular to the axis z.

The washer body (1b) has two parallel planes (also referred to as an upper plane (1u) and a lower plane (1w) for convenience in this embodiment), and an inner peripheral surface defining a bolt hole (1h) in the center. It has (1i) and an outer peripheral surface (1о) that is radially outside the bolt hole (1h). The bolt hole (1h) is a hole through which a bolt is penetrated, and has a diameter R slightly larger than the bolt diameter according to the assumed bolt diameter. For example, the bolt hole diameter of a nut for a nominal M10 (thread diameter of 10 mm) may be 11 mm. The surface (inner peripheral surface (1i)) defining the diameter R of the bolt hole (1h) is parallel to the axis in the vertical cross-sectional view including the axis as shown in FIGS. 13 to 15. The shape of the cross section of the bolt hole (1h) (shape in the plan view) is not limited, but is usually circular. The bolt hole (1h) of the washer (1) is predetermined with respect to the outer diameter of the bolt in order to stably arrange the washer (1) with respect to the bolt by penetrating the bolt through the bolt hole (1h). It is preferably circular in size. However, it is preferable that the inner peripheral surface of the eaves portion (1p) described later is composed of the inner peripheral surface (1i) of the bolt hole, but the inner peripheral surface (1i) of the eaves portion (1p) is a plan view. In the (cross-sectional view), it is not necessary to exist on the entire circumference of the circular bolt hole (1h), and it is sufficient that the bolt can be positioned with respect to the bolt by forming two or more protrusions. When having this protruding eaves portion (1p), the space between the protrusions in the plan view is not a bolt hole in the present invention. In the plan view, the space between the bolt hole and its protrusion is continuous. Considering the space between the protrusions as a bolt hole, the planar shape of the bolt hole is not circular, but in such a case, the bolt hole is a virtual circular hole of the washer body (1b). Only the inner peripheral surface (1i) constituting the virtual circular hole is considered as the inner peripheral surface (1i) of the bolt hole.

In the vertical sectional views of FIGS. 13 to 15, the washer body (1b) has a second stress non-transmission space (12s) that opens into the bolt hole (1h), and the second stress non-transmission space (12s) is a lower plane. It is also open to (1w). The boundary line between the second stress non-transmission space (12s) and the washer body (1b) rises almost vertically from the lower plane (1w) (rising edge (Br)) and passes through the corner of a curve close to an arc. It approaches the upper plane (1u), extends to the inner peripheral surface (1i) (the surface defining the bolt hole (1h)) of the washer body (1b), and extends above the second stress non-transmission space (12s). Part (1p) is formed. The rising portion (Br) rising substantially vertically from the lower plane (1w) may be within an angle of ± 20 degrees with respect to the vertical direction in consideration of manufacturing accuracy.

The second stress non-transmission space (12s) has an upwardly convex cross-sectional shape shown in FIGS. 13 to 15 in the vertical cross-sectional view, but three-dimensionally, the axis of the bolt hole (1h) of the washer (1). It is a concentric ring centered on (see FIGS. 15 (b) and 15 (c)). That is, the second stress non-transmission space (12s) is a three-dimensional space (concentric annular space) formed by rotating the cross-sectional space shown in FIGS. 13 to 15 by 360 degrees around the axis.

With reference to FIGS. 13 to 15, the second stress non-transmission space (12s) is opened in the bolt hole (1h) in the vertical cross-sectional view of the washer. Since the second stress non-transmission space (12s) is opened in the bolt hole (1h), the axial transmission of the fastening force on the bolt hole side of the washer body (1b) is blocked, so that the bolt hole side The force applied to the lower ridges of the fastening mesh of a certain bolt is reduced.

When the washer on the second side surface is used together with the nut, the compressive stress from the contact surface between the washer (1) and the nut (4) to the threaded portion of the bolt (3) is due to the presence of the second stress non-transmission space (12s). It is limited to the outside of the second stress non-transmission space (12s), and as a result of wrapping around from the outside of the second stress non-transmission space (12s) to the bolt hole side, the direction in which the compressive stress extends to the bolt hole side is the second. It is a region having an elevation angle (angle θ) of about 45 degrees or less with respect to the axis z from the position Ps farthest in the radial direction from the bolt hole in the stress non-transmission space (12s). The compressive stress that bends toward the bolt hole side at an angle of about 45 degrees or less with respect to this axis z is applied to the bolt fastening meshing low-order peak by moving toward the open side of the bolt's higher-order peak (especially the peak). We found a favorable feature that the stress is small. When the radial dimension of the second stress non-transmission space (12s) is set to an appropriate dimension or less, the outer diameter dimension of the nut and washer can be kept small while sufficiently reducing the stress applied to the low-order thread. It is preferable because it can be done.

In one aspect of aspect B of the second side surface, the radius from the position Ps farthest from the axis of the second stress non-transmission space (12s) to the inner peripheral surface (1u) parallel to the axis of the bolt hole (1h). The distance L in the direction is
0.5p ≦ L ≦ 5.6p, more preferably 0.7p ≦ L ≦ 5.6p, 1.0p ≦ L ≦ 5.0p, still more preferably 1.5p ≦ L ≦ 4.5p, especially 2. 0p ≦ L ≦ 4.0p, and further 2.5p ≦ L ≦ 3.5p
(In the formula, the diameter of the bolt hole is R, the unit of R and p is mm, and R and p have the above-mentioned relationship.)
It is preferable to satisfy.

In the vertical cross-sectional view of FIGS. 13 to 15, the washer body (1b) has an eaves portion (1p) on the upper side of the second stress non-transmission space (12s). The eaves portion (1p) is a member for centering with the bolt 3 with respect to the bolt hole (1h), and the tip of the eaves portion (1p) may form the inner peripheral surface of the bolt hole (1h). .. The eaves (1p) forming the inner peripheral surface (1i) of the bolt hole (1h) do not necessarily exist on the entire circumference of the bolt hole (1h) in the plan view of the washer body (1b), but all of them. It is preferable to define a circular bolt hole (1h) existing on the circumference. Since the eaves (1p) is not a part that transmits stress, the vertical thickness of FIGS. 13 to 15 may be as small as long as the strength of the eaves (1p) is maintained, and the smaller the thickness, the smaller the stress transmission. It is preferable because the contribution to is small. For example, it is desirable that the minimum thickness (Th) of the eaves portion (1p) is 0.1 times or more and 0.7 times or less the thickness T of the washer. More preferably, Th is 0.2T ≦ Th ≦ 0.6T, and even more preferably 0.22T ≦ Th ≦ 0.5T. The thickness of this eaves (1p) can be partially reduced, and if the shape is the thinnest on the way to the inner peripheral surface of the bolt hole through the corner, centering with the bolt on the innermost diameter side It is possible to secure the length of the inner peripheral surface (1i) that can be easily performed.

With reference to the vertical sectional views of FIGS. 13 to 15, the fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is approximately the same as the lower plane (1w) of the washer body (1b). It has a corner portion (Bc) that connects a rising portion (Br) that rises vertically and a portion that defines an eaves portion (1p) facing a bolt hole (1h). The boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s), particularly the boundary line (B4) at the corner portion (Bc), which is an upwardly convex curve in FIGS. 13 to 15, is It is preferable that the whole is composed of a curved line or a combination of curved lines and straight lines, and is composed of stress concentration relaxation lines having no corners where straight lines intersect. The corner portion (Bc) is not limited, but in the vertical cross-sectional view of FIGS. 13 to 15, from the position where the boundary line is in contact with a straight line forming 20 to 25 degrees, particularly 25 degrees with respect to the axis z. There is a position (P) where a straight line having an elevation angle θ of 45 degrees with respect to the axis z is in contact with the boundary line, which is a portion up to a position tangent to a straight line forming 65 to 70 degrees with respect to the axis z, particularly 65 degrees. It is the part to do. The corner portion (Bc) may be composed of, for example, a straight line having an elevation angle of about 40 to 50 degrees, particularly about 45 degrees. In that case, the connecting portion between the corner portion (Bc) and the rising portion (Br), It is preferable that the connecting portion between the corner portion (Bc) and the eaves portion (1p) is joined by a curved line so as not to form a corner. Further, the corner portion (Bc) may be formed by an arc, an elliptical arc, or a shape close thereto. The area from the corner portion (Bc) to the inner peripheral surface of the bolt hole (1i) is the inner peripheral end portion (Be) of the bolt hole.

In one embodiment, referring to the vertical cross-sectional views of FIGS. 13 to 15, the fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is the lower plane of the washer body (1b). A bolt that rises almost vertically from (1w) and is connected to an arc or elliptical arc or a composite line in which both sides are connected to a curve to form a corner portion (Bc), and then the curvature is further reduced. The inner peripheral surface of the bolt hole (1i) may be reached by the inner peripheral end portion (Be) of the hole. Such a fourth boundary line (B4) is a stress concentration relaxation curve except for the connection point with the lower plane (1w) and the inner peripheral surface of the bolt hole (1i), and is a second stress non-transmission space having this shape (1i). 12s) is easy to form. Further, when the position P where the straight line having an elevation angle of 45 degrees with respect to the axis is in contact with the corner portion (Bc) is close to the upper plane (1u), the compressive stress transmitted from the object to be fastened (2) to the screw is not transmitted as the second stress. The position around the outside of the space (12s) has an effect of being farther from the inner peripheral surface (1i) of the bolt hole, which is preferable. The position P where the corner portion (Bc) is in contact with a straight line having an elevation angle of 45 degrees with respect to the axis is located at an axial distance of 1/2 or more of the thickness T of the washer (1) from the lower plane (1w) of the washer body (1b). It is preferably less than or equal to the length of one pitch of the screw from the position P3 (Ps) of the starting point of the rising portion (Br) on the lower plane (1w) of the washer body (1b) toward the inner peripheral surface (1i) of the bolt hole. It is preferable to have. The rising portion (Br) (from the lower plane (1w) to the position where a straight line having an elevation angle of 20 to 25 degrees with respect to the axis touches the fourth boundary line (B4)) is not limited, but is 1 of the thickness T of the washer (1). It is preferable to have an axial length of / 4 to 1/3 or more. The end of the inner circumference of the bolt hole (Be) (from the position where the straight line with an elevation angle of 65 to 70 degrees with respect to the axis touches the fourth boundary line (B4) to the inner peripheral surface of the bolt hole (1i)) is the connection point with the corner (Bc). The shape is such that the elevation angle formed by the tangent line with respect to the axis gradually increases from the bolt hole inner peripheral surface (1i), and the maximum elevation angle is preferably 90 degrees or less. The minimum thickness of the eaves (1p) formed above the bolt hole inner peripheral end (Be) (thickness t of the bolt hole inner peripheral surface (1i) in FIG. 14) is the thickness T of the washer (1). It is preferably in the range of 3 to 20%, more preferably 5 to 15%. The inner peripheral end portion (Be) of the bolt hole may have various deformations as shown in FIGS. 19 and 20, and further, the inner peripheral end portion (Be) of the bolt hole does not exist and is in the middle of the corner portion (Bc). Alternatively, the end may be a connection point with the inner peripheral surface (1i) of the bolt hole.

(FEM analysis result of washer of aspect B)
Washers (1), nuts (4) and bolts (1), nuts (4) and bolts (4) when the nut (4) is tightened to the bolt (3) using the washer of aspect B of the second aspect of the present invention as shown in FIG. The stress applied to 3) was analyzed by FEM. All the elements such as the thread shape of bolts, nuts and washers, member strength, member Young's modulus, Poisson's ratio, fastening torque, and axial force were applied as specified in JIS {ISO}. However, it is assumed that the thickness of the flange portion of the nut and the strength of the screw shaft portion have sufficient strength. There is no particular regulation in JIS for this part, and it is assumed that the minimum strength is recommended. A fine screw pitch was adopted (bolt screw diameter M = 12 mm, screw pitch P = 1.25 mm).

FIG. 16 shows a Mises equivalent stress distribution diagram. In FIG. 16, the Mises equivalent stress is larger as the color is whiter and smaller as the color is blacker. Gray has an intermediate size, and the black part indicates that the stress is smaller than that of white. Comparing FIG. 16 with FIG. 4 of the washer having the conventional structure, it can be seen that the range and position of the large stress of white are clearly different. In FIG. 16, it can be seen that the range of light gray and dark gray extends to the fifth thread, and the black (small stress) portion becomes smaller. FIG. 16 shows that the stress distribution shows that the stress is diffused after the third thread. Looking at the white part where the Mises equivalent stress is large, the large Mises equivalent stress extends from the corner of the concave space mainly at an elevation angle of 45 degrees or a little smaller than the screw axis direction. It can be seen that there are white and gray parts representing a large Mises equivalent stress in the subsequent (5th mountain). In this way, if the destination where the Mises equivalent stress, which is larger than when there is no recessed space, goes to the third and subsequent threads of the nut screw, the stress load sharing ratio of the first thread is set, and when there is no recessed space. Can be reduced compared to.

17 (a) and 17 (b) are bar graphs comparing the load sharing ratio and the load sharing ratio of each thread of the washer of aspect B and the washer of the conventional structure obtained by FEM analysis. In the model used in FIG. 16, the distance Ls is set to 2.21 times p (1.25 mm). The load sharing rate of the first thread of fastening engagement is 32.3%, which is 3.3 points in absolute value and 9.3 in relative ratio compared to the same load sharing rate of 35.6% for the washer of the conventional structure. It has been shown to be reduced by%.

In the left figure of FIG. 18, in the washer of aspect B of the second side surface, the horizontal axis is L / p (since the pitch p is the same, it is equivalent to the case where the distance L is changed), and the load sharing ratio of the first meshing peak is set. It is a graph which shows. The upper right figure of FIG. 18 is the Mises equivalent stress distribution diagram of the washer fastening of the conventional structure corresponding to FIG. 1, the middle right figure is the Mises equivalent stress distribution diagram of model 2 (L = 1.81p), and the lower right figure is. It is a Mises equivalent stress distribution diagram of model 3 (L = 2.60p). In the model 2 and the model 3, the shape of the second stress non-transmission space (12s) is almost the same as the shape of the rising portion and the corner portion, and in the model 3, the eaves portion (1p) is different in the radial direction as compared with the model 2. It has a long shape. With reference to these Mises equivalent stress distribution maps, it can be seen that the white part with high stress extends from the first thread to the higher-order thread side from the upper right figure to the middle right figure and the lower right figure. .. From these figures, the load sharing ratio of the first thread of the bolt screw at each black spot position is 35.6% in the upper right figure (conventional washer), 32.3% in the middle right figure, and 30.9% in the lower right figure. %Met. It is shown that the load sharing ratio of the first thread of the screw decreases substantially linearly as the distance L (L / p) increases, and the load sharing ratio of the first thread of the bolt screw decreases as the distance L (L / p) increases. The absolute value decreased from 35.6% to 30.9% by 4.7 points, and the relative ratio decreased by about 13%. By reducing the load on the first thread, it is effective in improving the fatigue strength of the bolt meshing on the bottom of the first thread. From the relational expression of the SN diagram obtained from the bolt fatigue test results described above, the load sharing ratio is from 35.6% to 34.5%, 32.3%, 30.9%, 30.3. When it decreases to% and 29.7%, respectively, the stress index b = 4, and the Nf and lifetime are about 1.12 times, about 1.45 times, about 1.75 times, about 1.92 times, and about 2. It is expected to increase by 13.13 times.

(Modification example of aspect B of the second stress non-transmission space)
19 (a) to 19 (c) and FIG. 20 show a schematic diagram of a modified example of the second stress non-transmission space (12s). In FIG. 19, B4 is a boundary line between the washer body (1b) and the second stress non-transmission space (12s).
FIG. 19A is an example in which the axial length (t) of the bolt hole inner peripheral surface (1i) is longer than the minimum thickness (Th) of the eaves portion (1p).
FIG. 19B shows an example in which a stress concentration relaxation curve structure is attached to a portion from the contact position between the object to be fastened and the washer (1) to the rising portion (Br), and the distance L in this case is shown. It is on the outer peripheral side in the radial direction from the rising portion (Br) as in.
In FIG. 19 (c), a second stress non-transmission space (12 s) that is convex from the inner peripheral side of the bolt hole to the outer peripheral side is provided in the middle of the thickness of the washer body, and the second stress non-transmission space (12 s) is provided. This is an example in which the washer body is not opened on the upper and lower planes (1u, 1w). FIG. 19C is an example in which two washers of FIG. 19B are attached facing each other. When the thickness (T) of the washer body is thick, by providing a stress non-transmission space (12s) as shown in FIG. 19 (c) near the nut, the thread load sharing ratio of the first meshing thread can be increased. It can be reduced. Further, in this example, the upper and lower planes of the washer are the same, so that there is no misuse during use.
-Fig. 19 (d) shows a shape that takes into consideration the centering of the washer, and shows a method of increasing the length t of the inner peripheral surface of the bolt hole (see the shape on the bolt hole side) and a ring shape on the nut side on the outer peripheral side. A modified example of a method of providing several protrusions and using the outer periphery of the nut to align the center with the bolt (see the protrusions on the outer circumference of the washer body) is shown. In the example of FIG. 19D, since the bolt (3) and the washer (1) are centered using the outer peripheral portion of the nut, the diameter of the bolt hole may be larger than the expected diameter of the bolt. .. In that case, it is used for a bolt having a screw with a pitch smaller than the value of p based on the definition in the inequality 0.5p ≦ L ≦ 5.6p based on the diameter R of the bolt hole in the example of FIG. 19 (d). However, when the above inequality is satisfied, the effect of reducing the load sharing ratio of the first thread of the bolt screw can be obtained.
In FIG. 20, the corner portion (Bc) of the boundary line (B4) of the second stress non-transmission space (12s) is composed of a straight line, and both the rising portion (Br) and the inner peripheral end portion (Be) of the bolt hole are composed of a straight line. This is an example in which the connecting portion between the corner portion (Bc), the rising portion (Br), and the inner peripheral end portion (Be) of the bolt hole is formed by a curved line.

The washer (1) on the second side surface of the present invention has two planes, that is, the first plane and the second plane (1u, 1w), but the bolt (3) and the nut (4) are used to fasten the object (2). ) Is used with either of the two planes of the washer (1) facing the object to be fastened (or the nut side). Whether the washer on the second side surface is aspect A or aspect B is aspect A or aspect when one of the two planes is considered as the first plane (1u) (nut side, upper plane). The requirement of B may be satisfied. Therefore, one washer may be a washer of aspect A when one plane is considered as the first plane (1u), and a washer of aspect A when the other plane is considered as the first plane (1u). it can. In such a case, the washer can be used as the washer of the aspect A regardless of which plane is used as the upper plane. Further, one washer can be a washer of aspect A when one plane is considered as a first plane (1u), and a washer of aspect B when the other plane is considered as a first plane (1u). .. A washer that satisfies the requirements of aspect A can often be used as it is as a washer of aspect B by turning over the upper and lower planes. On the other hand, the washer satisfying the requirement of the aspect B may be used as the washer of the aspect A by turning over the upper and lower planes, but in order to use it as the washer of the aspect A, the portion connecting the rising portion and the lower surface is stress-free. It is preferably configured as a concentrated curve.

It is also possible that one washer has two stress non-transmission spaces (1s), and the two stress non-transmission spaces (1s) satisfy the requirements of aspect A and the requirements of aspect B, respectively. In such a case, the washer is both the washer of the aspect A and the washer of the aspect B when one plane is used as the upper plane, but the washer has a substantially large effect of reducing the burden on the first mountain when used. It is thought that it acts as a washer. However, the washer of the second aspect of the present invention is manufactured with the intention of being used as either aspect A or aspect B, even if the requirements of aspects A and B are met at the same time. It goes without saying that it is preferable to use it in the intended manner.

(Washer thickness)
The thickness of the washer (1) of the present invention (axial dimension between the upper and lower planes) is 0.1 with respect to the bolt hole diameter R as the thickness T in the washer main body portion in which the stress non-transmission space is not formed. It may be double or more, 0.2 times or more, further 0.5 times or more, and may be 20 times or less, 10 times or less, and further 1.0 times or less.

In one aspect of the washer of aspect A of the present invention, the thickness (T) is 0.1 times or more the inner diameter of the bolt hole, preferably 0.2 times or more and 2.0 times or less the diameter of the bolt hole, and more preferably. May be 0.3 times or more and 1.5 times or less the bolt hole diameter.

(Outer circumference of washer)
The outer peripheral surface of the washer (1) of the present invention is the contact surface (upper plane) of the washer (1) with the nut (4) and the object to be fastened (2) of the washer (1), referring to FIG. It is preferable that the contact surface (lower plane) has a sufficient area for fastening the object to be fastened (2) from the nut (4) and the washer (1). The area for fastening the object to be fastened (2) with the nut (4) and the washer (1) may be the same as that in the conventional washer having no stress non-transmission space (1s). The outer peripheral surface of the washer (1) in the conventional washer may have a size having an inscribed circle of about twice the bolt hole diameter (for example, within 2R ± 10%).

In one aspect of the present invention, the outer peripheral surface of the washer (1) of the present invention has a diameter D _{1 of} a circle inscribed in the outer circumference of the upper plane (1u) of the washer body (1b) and a bolt hole diameter R. It may be ₁ = nR (n ≧ 1.8, further n ≧ 1.9, n ≧ 2.0, n ≧ 2.2). Here, the bolt hole diameter R is the diameter of the center hole defined by the inner peripheral surface of the washer body (the same applies to other parts in the present disclosure).

In one aspect of the present invention, the outer peripheral surface of the washer of the present invention has a diameter of a circle inscribed in the outer peripheral surface of the upper plane of the washer in the plan view of the upper plane of the washer body (1b), which is 2 of the bolt hole diameter. The size may be greater than or equal to the sum of the double (or within ± 10% of that; same as above) and the distance L at the position Ps from the inner peripheral surface of the bolt hole. _{D o = nR + L (n} ≧ 1.8, more n ≧ 1.9, n ≧ 2.0, n ≧ 2.2) may be.

In another aspect of the present invention, for example, the diameter D _{0 of} the circle inscribed in the outer periphery of the upper plane of the washer body, the bolt hole diameter R, and the distance L from the inner peripheral surface of the bolt hole at the position Ps are set to (D). _{^{^{0/2) 2 - (R}}} / 2 + L1) 2 = 3k (R / 2) 2 ( wherein, is suitable to be k ≧ 0.8). In the formula, k = 0.8 to 1.5, more preferably k = 0.9 to 1.3. Further, in the vertical cross-sectional view of the washer, it is preferable that the outer peripheral surface of the washer body is not on the inner peripheral side from the position where it intersects the straight line having an elevation angle of 45 degrees passing through the position Ps. At this time, in the vertical cross-sectional view of the washer (1), the outer peripheral dimension on the lower plane 1w side is larger than the outer peripheral dimension on the upper plane 1u side of the washer body, so that the upper plane 1u side of the washer body is shown in FIGS. As shown in 12, inclined cutting (for example, an elevation angle of 30 to 60 degrees with respect to the axis line, particularly about 40 to 50 degrees) may be performed.

In one aspect of aspect A of the present invention, the outer diameter of the washer is 1.4 times or more and 4 times or less of the bolt hole diameter, preferably 1.5 times or more and 3.5 times or less of the bolt hole diameter, and more preferably bolts. The hole diameter may be 1.7 times or more and 2.8 times or less.

The outer circumference of the washer body (1b) may be larger than the outer circumference of the upper plane (1u) in contact with the nut. In the vertical cross section, the washer body (1b) may have a connecting portion between the outer circumference (1о) and the upper plane (1u) cut at an elevation angle of, for example, 30 to 60 degrees, and further 40 to 50 degrees. The size of the notch portion (1d) is the dimension in the thickness direction of the washer body (1b), and may be half or less, further one-third or less of the thickness (T) of the washer body (1b). ..

(Other shapes of Wassy)
The washer (1) of the present invention is preferably a solid body that does not form a space other than the stress non-transmission space in the washer main body (1b). However, a space other than the stress non-transmission space may be provided as long as the strength and fastening force of the washer of the present invention are not impaired.

The washer (1) of the present invention can chamfer the corners, and it is particularly preferable to chamfer with a curved line. Since the chamfering dimension is small, when considering the shape and dimensions of the washer body and the stress non-transmission space, the chamfering may be ignored or the chamfered portion may be excluded.

The other configurations and manufacturing methods of the washer (1) will be described below, but these matters are common to both the first aspect and the second aspect of the present invention.

(Washer material)
Regarding the material of the washer (1) of the present invention, metals, non-ferrous metals, various alloys, polymer resins, oxides, carbides, nitrides, composite materials (CFRP; carbon fiber reinforced plastic, etc.) used in the conventional washer. , Hard resin (for example, having a hardness of Vickers hardness Hv70 or more, and further Hv100 or more) can be used from one or a combination of two or more. It has sufficient strength to withstand the compressive stress at the time of fastening. In addition, the selection of material and strength can be decided by the selection by the engineer on the user side.

(surface treatment)
The washer (1) of the present invention can be subjected to surface treatment having effects such as rust prevention, decoration, slidability improvement, and identification, which have been conventionally required for washers. Specifically, one type such as metal plating, polymer coating, fluororesin coating, coating of DLC, TiN, CrN, BN by plasma coating treatment such as PVD, CVD, manganese phosphate chemical conversion treatment, alumite, electrolytic polishing, etc. It can be selected and used from two or more combinations. The washer (1) can be polished to improve the surface roughness in the previous step in order to secure the slidability with the nut (4). In particular, the part of the washer surface that comes into contact with the nut bearing surface is surface-treated with a small frictional resistance and a stable friction coefficient to improve the efficiency of converting the nut tightening torque into axial force, and the shaft due to friction variation. There is an advantage that the force generation fluctuation becomes small.

(S-DLC coating)
Since the surface of the washer (1) slides with the nut bearing surface with pressure, a surface having a small relative friction coefficient is desirable. The external force load applied not only at the time of initial fastening but also during use is input to each other between the nut seat surface and the washer. When fastening with reference to the tightening torque at the time of initial fastening, the frictional resistance between the nut bearing surface and the thread is included, and when the friction is large, the actual axial force generation is affected to be small. At this time, lubricating oil may be applied to reduce the frictional resistance of the thread and nut bearing surface. By this refueling, the coefficient of friction can be regarded as the same as that of oil, and the coefficient of friction drops to about 0.1. Considering that the friction coefficient of many metals is about 0.5 in a dry environment, the friction coefficient of 0.1 is a remarkably low value. For the same purpose, the surface of the washer may be fastened by applying manganese phosphate treatment, solid lubricant, molybdenum disulfide paste, etc. to reduce friction. Since such treatment has weak adhesion to the washer surface, it is not suitable for repeated retightening, disassembly, and refastening. As a surface treatment that can solve these problems, there is a solid lubricating layer film such as DLC (diamond-like carbon film), and among them, the DLC film is further subdivided and the surface is divided by grooves and the like, which is suitable for repeated fastening. It is a segment structure DLC in which a large number of discontinuous films are arranged. In the segment structure DLC (S-DLC), elastic deformation occurs significantly on the softer base material when the nut and washer come into contact with each other. Therefore, even if the thin film has high brittleness and high hardness, it follows the deformation of the base material. It is known that membrane destruction is unlikely to occur. When the washer is coated with a film having a low friction coefficient such as DLC, the friction becomes smaller within the range where the nut seat surface and the washer come into contact, so when the nut is tightened with the same torque, the seat surface resistance and friction coefficient vary. There is an advantage that it becomes smaller, the bolt axial force is improved, and the variation of the axial force is reduced. By coating the upper flat surface (nut seat surface side) of the washer with S-DLC, the friction reducing effect is most exhibited, and the effect of applying S-DLC is greatly exhibited.

In the case of the S-DLC coating, even if the washer undergoes a small elastic deformation, the destruction of the film is minimal, and when the fastening is completed, the torsional torque of the bolt is reduced without changing the axial force. It has the feature of being able to rotate. Being able to reduce the torsional torque of the bolt leads to the effect of delaying the start of loosening of the screw.

It is preferable that the sliding surface of the washer is formed so as to have surface roughness and flatness that do not hinder the rotation of the nut when it is screwed. As such surface roughness, the arithmetic average roughness Ra is preferably 50 μm or less, more preferably 6.5 μm or less, and the flatness is preferably 0.2 mm or less, further 0.05 mm or less. The arithmetic mean roughness Ra is measured according to JISB0601: 2013.

(Washer usage pattern)
Like the conventional washer, the washer (1) of the present invention can be used by being inserted between the object to be fastened (2) and the nut (4), for example, as shown in FIGS. 2 and 14. The nut (4) used together with the washer of the present invention may be a hexagon nut, but is preferably a flange nut. This is because, in the case of a flange nut, the area of the contact side surface with the washer can be increased without increasing the screw shaft portion other than the flange portion of the nut.

(Washer manufacturing method)
The washer manufacturing method can be roughly divided into i) removal processing (machine cutting processing, etc.) and ii) plastic working (press processing, forging processing, etc.). i) is made from materials using machine tools such as NC lathes, precision automatic machines, and general-purpose lathes, and cutting tools, and has the characteristics dedicated to the object to be used. ii) is excellent in manufacturing a large number of general-purpose products with the same shape, and is continuously manufactured using a mold. As an example, a small object is punched from a plate by press working to determine its shape and dimensions, and a deburring process and surface treatment result in a finished product. In addition, when making medium to large washers, it is possible to create a shape by continuous forging from the material by the cold forging (fine blanking) method, finishing processing such as surface roughness and flatness, surface When there is post-process work such as processing, it becomes a finished product by performing that part.

When manufacturing by the above machining (machining, cutting), machine tools such as NC lathes (including automatic machines) that process one by one often use end mill-shaped special cutting tools, so special cutting tools The shape of the cutting edge is important. Since the seat surface of the conventional washer is almost flat, the cutting tool is also suitable for cutting a flat surface. In order to cut out the washer of the present invention, it is necessary to cut out the stress concentration relaxation curve, and by using a molded blade whose blade part is finished in a special shape in advance, the NC program (numerical control part) of the machine tool It is easy to create an elliptic curve that is not provided in), and there is no need to create an external program in advance, which makes it rational to reduce man-hours.

About the cutting tool for forming the washer of the present invention:
It is roughly divided into 1; the case where the structure is directly processed by machining and 2; the method where a mold is created and the shape is transferred using this mold. In the case of direct machining of 1, by forming an end mill-shaped blade similar to a drill for drilling into a shape that suits the purpose, "easy to cut, suitable for machine tools, strength and durability of the blade There is a track record. " In the case of 2, since the object to be processed is finally a product, the transferred shape has a so-called male-female relationship. In order to cut such a shape, it is desirable to use a cutting tool having a curved line that has the structure of the washer of the present invention. Cutting tools are not limited to cutting, but also include grinding wheels.

21 (a) to 21 (e) show some examples of special shapes of cutting tools. The white part is the cross section of the cutting tool 21, and the //// part (diagonal line portion) around it is a modification of the cutting tool 21 in which the cutting blade 22 is provided. Since the shape of the cutting blade 22 corresponds to the shape of the stress non-transmission space, when the cutting tool 21 rotates, the cutting blade 22 creates a space having a cross-sectional shape of a //// part (diagonal portion) in the bolt hole portion of the washer. Is formed.
FIG. 21A shows an end mill shape, in which the boundary lines B3 and B4 of the washer structure are formed into a blade shape 22 formed in the shape of an ellipse or a circle, and can correspond to many hole diameters.
FIG. 21 (b) shows a drill 23 in the center and blades 22 forming a stress relaxation curve similar to that in (a) added to both sides of the drill 23 in a guide hole provided in the object to be cut. Therefore, it is easy to align the center of the hole with the center of the washer structure.
-Fig. 21 (c) has a structure in which protrusions can be mainly carved out, such as a mold, and is used when the shape of the object to be transferred is a mold to be a mother.
21 (d) is an example used when a structure is formed on the bolt hole side of the washer shown in FIG. 19 (c). When the washer is in the shape of a long pipe, it is suitable for forming the washer structure of aspect B near the inner diameter end of the pipe. In addition to this, there are many modified examples depending on the intended use. In particular, when creating a stress concentration relaxation curve such as an ellipse or a circle, if a desired shape is previously inserted in the cutting tool to be used, an NC machine tool can easily create a shape having the desired stress concentration relaxation curve.

In order to make the washer (1) of the present invention by plastic working, a desired washer structure can be made by weaving a desired shape into a mold in advance. The manufacturing method does not change at all except that the mold shape is different, and various washers of the present invention can be obtained without increasing man-hours. Since the transfer mold of the mold becomes a product, it is rational that the cutting tool for cutting the mold also has a shape that forms a stress concentration relaxation curve. The forging method is the same.

When making a thin washer, a mold for plastic working is often used. To give an example of the manufacturing order, i) punch the inner diameter hole, ii) form the washer structure forming part of the present invention provided in the die into a push-in shape, iii) punch the outer diameter part, iv) deburring. Perform, v) Surface treatment is performed to obtain a finished product. Here, i) and ii) can be performed with the same mold. By devising the mold in this way, the product of the present invention can be produced without increasing the man-hours. An example of this mold is shown in FIG. A casting method may be adopted when making a thick washer, a washer having a special material, a large washer, or the like, and an example of a mold at that time is shown in FIG. If the mold is provided with a curved surface in advance, the washer of the present invention can be made by the conventional casting technique. There is no increase in processing man-hours.

FIG. 22 shows a vertical cross-sectional view of a punch die as an example of a die. The thick black line between the male type (upper part) 31 and the female type (lower part) 32 represents the workpiece 33. Before machining, the workpiece 23, which is a flat plate (shown by the dotted line), undergoes press plastic working with punch dies (die) 31 and 32 based on the hole, and the shoulder to hole portion is deformed downward into an elliptical shape. .. The corners of the washer holes have the shape of a washer structure. At the time of use, the bolt thread comes out from the lower side of the figure, and the nut bearing surface is screwed into the bolt from the upper side. In addition, as in the past, it can be said that the man-hours required to create the structure do not increase if the target processing can be performed by one press processing. The mold is a dedicated mold, so there is no mistake in the hole position, direction, etc.

FIG. 23 shows an example of the casting mold 41. The ring-shaped casting 42 is shown in black, and the shaded area indicates the casting mold 41. Although the shape is simplified, the black arrow points to the gate 43, from which molten metal is poured to fill the space, and after cooling, a black product is produced. If the shape of the washer structure is prepared in advance in the mold (casting mold) indicated by the diagonal line, the desired washer structure is transferred to the product. Since the casting method can be formed from all directions instead of one-way processing such as press working, for example, a block-shaped mold is provided with multiple mold shapes, and a washer structure is installed inside the mold at once. It has the feature that it can be made with different dimensions from multiple angles. Molds such as casting, die casting, MIM (metal powder injection molding), lost wax, injection molding, etc., which are molded by melting materials and putting them in a mold, can have endless application deformation examples.

Cutting tool material The material of the cutting tool for processing can be selected and used from alloy steel, cutlery steel, carbides such as tungsten carbide (WC), ceramics, and nitrides, which have been proven in the past.

Surface treatment As described above, the washer (1) of the present invention can be subjected to a surface treatment having effects such as rust prevention, decoration, slidability improvement, and identification, which have been conventionally required for washers.

Surface treatment of cutting tools In addition to the conventional high-frequency quenching, carburizing quenching, and nitriding treatment, the surface of the cutting tool can be coated with a cured film to improve durability. A thin film coating method that can coat a coating thin film such as DLC, TiN, TiC, CrN, BN, Al ₂ O ₃ is PVD (physical vapor deposition), CVD (chemical vapor deposition), arc ion plating, sputtering, FCVA (filter type cassette). Dick vacuum arc), magnetron sputtering, PBII (plasma-based ion injection method), DC single-pulse CVD and the like can be used.

The present invention proposes an improvement in the structure of a washer used in a properly tightened bolt / nut fastener. By improving the washer structure of the present invention, not only the load sharing rate of the first thread of the bolt meshing is reduced, but also the load sharing rate of each thread is leveled, and the fatigue breakage from the threaded portion of the bolt is effective. It is possible to increase the strength.

1 Washer 1b Washer body 1h Bolt hole 1u Upper plane (first plane)
1w lower plane (second plane)
1h Bolt hole 1s Stress non-transmission space 1p Eaves 1i Bolt hole inner peripheral surface 1о Outer surface of washer 2 To be fastened 3 Bolt 3h Bolt head 4 Nut 4e Line connecting the thread valley bottom of the nut 4o Open side of the nut thread (arrow The direction is the direction to loosen the screw)
4c Nut thread fastening side (arrow direction is the direction in which the screw is tightened)
4w The surface in contact with the washer of the nut 4s Screw shaft of the nut 4f Flange of the nut 5 Base 11s First stress non-transmission space 12s Second stress non-transmission space 21 Cutting tool 22 Cutting edge cross section 23 Drill 31 Male type 32 Female type 33 Work piece 41 Casting mold 42 Casting 43 Gate
B1 to B6 Boundary line Br Boundary line of rising edge Bc Boundary line of corner part Be Boundary line of inner peripheral end of bolt hole p Screw pitch z Axis line r Radial direction θ Elevation angle Pt Top plane start position of first stress non-transmission space Pо Above Intersection of the plane and the extension of the inner peripheral surface of the bolt hole P1 Start position of the inner peripheral surface of the bolt hole in the second stress non-transmission space P2 End point position of the inner peripheral surface of the bolt hole in the second stress non-transmission space P3 Lower plane end point of the second stress non-transmission space Position Ps The position farthest in the radial direction from the inner peripheral surface of the bolt hole in the stress non-transmission space R Bolt hole diameter of the washer Do Outer circumference of the washer Ls Distance from position Ps to the line connecting the bottom of the bolt hole L position Ps to the inner peripheral surface of the bolt hole Distance from Lh washer Top plane to position Ph T Washer thickness Th Minimum thickness of eaves t Thickness of bolt hole side end of eaves * Destructible bolt meshing 1st thread valley bottom Position of

Claims

A bolt (3) extending from the substrate (5) side is inserted into a bolt hole (1h) of the object to be fastened (2) and a washer (1), and the washer (1) is inserted by the bolt (3) and the nut (4). It is a washer fastening structure for fastening the object to be fastened (2) to the substrate (5).
The bolt (3), the washer (1), the nut (4), and the washer fastening structure have a common axis and axis direction (hereinafter, also simply referred to as "the axis" and "axis direction") and the axis. It has a vertical radial direction (hereinafter, also simply referred to as "the radial direction").
The washer (1) has a washer body (1b) and a bolt hole (1h) penetrating the washer body (1b).
The washer body (1b) has a stress non-transmission space (1s) that is a concentric annular shape centered on the axis of the bolt hole (1h).
The washer fastening structure, wherein the stress non-transmission space (1s) is open to the bolt hole (1h).
In the radial direction, the side closer to the axis is the inside, and the side far from the axis is the outside.
The direction from the object to be fastened (2) to the washer (1) and from the washer (1) to the nut (4) is upward, upward or upward, and the opposite direction is downward, downward or downward.
The nut (4) has a flat lower plane (4w) extending in the radial direction and a screw extending in the axial direction, and the screw is alternately composed of threads and threads, and is a screw. Has a pitch p and
The stress non-transmission space (1s) of the washer body (1b) is formed from the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in a vertical cross section including the axis of the washer (1). The distance Ls in the radial direction from the position Ps to the extension line (4e) of the line connecting the screw valley bottoms of the nut (4) is the said distance Ls of the nut (4), where Ps is the position farthest to the outside in the radial direction. The washer fastening structure according to claim 1, which has a length range of more than 0.5 times and 6 times or less the screw pitch p.
The washer body (1b) has a flat upper plane (1u) extending in the radial direction on the nut (4) side and a flat lower surface (1u) extending in the radial direction on the object to be fastened (2) side. It has a flat surface (1w) and a bolt hole inner peripheral surface (1i) parallel to the axis line defining the bolt hole (1h).
The washer (1) has a thickness (T) from the upper plane (1u) to the lower plane (1w).
The stress non-transmission space (1s) is a first stress non-transmission space (11s) that opens in the bolt hole (1h) and also in the upper plane (1u) of the washer body (1b).
The first stress non-transmission space (11s) is formed in a vertical cross section including the axis of the washer (1).
The extension line of the upper plane (1u) of the washer body (1b) is defined as the first boundary line (B1), and the extension line of the inner peripheral surface of the bolt hole (1i) is defined as the second boundary line (B2). Position Pt below the one boundary line (B1) and outside the second boundary line (B2) in the radial direction and above the first boundary line (B1) and the position of the second boundary line (B2). It is a space where the line connecting Ph is the third boundary line (B3).
The position where the first boundary line (B1) intersects the second boundary line (B2) is Po, and the distance Lh in the axial direction from the position Ph to the position Ph is the screw of the nut (4). It is in the range of 0.01 times or more of the pitch p to 99% or less of the thickness T of the washer (1).
The first stress non-transmission space (11s) is a space surrounded by the first boundary line (B1), the second boundary line (B2), and the third boundary line (B3) in the vertical cross section. A concentric annular three-dimensional space formed by rotating the washer (1) around the axis.
(Hereinafter, the washer fastening structure having the first stress non-transmission space (11s) is referred to as "aspect A".)
The washer fastening structure according to claim 2.
In the aspect A, in the vertical cross section, the third boundary line (B3) of the first stress non-transmission space (11s) is at least deep in the axial direction from the first boundary line (B1). The washer according to claim 3, wherein the region up to 0.1 times the screw pitch p is composed of a curved line or a combination of a curved line and a straight line, has no corners, and is a stress concentration relaxation line. Fastening structure.
In the aspect A, in the vertical cross section, the third boundary line (B3) of the first stress non-transmission space (11s) is a fastening force applied to the upper plane (1u) of the washer body (1b). Is applied to the washer (1) assuming that the upper plane (1u) of the washer (1) is flat from the position Pt to the position Po, and is generated in the washer of the assumption. In the stress distribution equivalent to Mieses, the bolt hole is more than the stress distribution line on the bolt hole (1h) side where the relative stress is 95% based on the magnitude of the stress equivalent to Mieses applied vertically downward from the position Pt. The washer fastening structure according to claim 3 or 3, which is on the (1h) side.
The washer body (1b) has a flat upper plane (1u) extending in the radial direction on the nut (4) side and a flat lower surface (1u) extending in the radial direction on the object to be fastened (2) side. It has a flat surface (1w) and a bolt hole inner peripheral surface (1i) parallel to the axis line defining the bolt hole (1h).
The washer (1) has a thickness (T) from the upper plane (1u) to the lower plane (1w).
The stress non-transmission space (1s) of the washer body (1b) is a second stress non-transmission space (12s) that does not open in the upper plane (1u) of the washer body (1b).
The second stress non-transmission space (12s) is radially outside from the position P1 of the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section including the axis of the washer (1). The line extending to the position Ph of the inner peripheral surface (1i) of the bolt hole or reaching the position P3 of the lower plane (1w) of the washer body (1b) is defined as the fourth boundary line (B4), and the bolt. A space in which the extension line of the inner peripheral surface (1i) of the hole is the fifth boundary line (B5), or the extension line of the lower plane (1w) of the washer body (1b) is the sixth boundary line (B6). ,
The minimum thickness (Th) of the eaves, which is the shortest dimension in the axial direction from the upper plane (1u) of the washer body (1b) to the second stress non-transmission space (12s), is the thickness of the washer 1. 1% or more of T,
The second stress non-transmission space (12s) is the fourth boundary line (B4) and the fifth boundary line (B5), or the fourth boundary line (B4) and the fifth boundary line (B4) in the vertical cross section. It is a concentric annular three-dimensional space formed by rotating the space surrounded by the B5) and the sixth boundary line (B6) around the axis of the washer (1).
(Hereinafter, the washer fastening structure having the second stress non-transmission space (12s) is referred to as "aspect B").
The washer fastening structure according to claim 2.
In the aspect B, in the vertical cross section, the second stress non-transmission space (12s) is also opened on the lower plane (1w) side of the washer body (1b), and the fourth boundary line (B4). ) Extends upward from the lower plane (1w) of the washer body (1b) at an angle within 20 degrees with respect to the axis direction, and is in contact with a straight line forming an elevation angle of 20 to 25 degrees with respect to the axis. A corner portion (Bc) connecting the rising portion (Br) leading to the position and a position in contact with two straight lines forming elevation angles of 20 to 25 degrees and 65 to 70 degrees with respect to the axis, and the corner portion (Bc) connecting the corner portion to the above. The washer fastening structure according to claim 6, further comprising a bolt hole inner peripheral end portion (Be) leading to the bolt hole inner peripheral surface (1i).
In the aspect B, in the vertical cross section, the fourth boundary line (B4) is a connection point of the washer body (1b) with the lower plane (1w) and / or the inner peripheral surface of the bolt hole (1i). The washer fastening structure according to claim 6 or 7, wherein the stress concentration relaxation line is composed of a curved line or a straight line with a curved line and has no corners.
In the plan view of the fastening structure viewed from the axial direction, the contact surface between the upper plane (1u) of the washer (1) and the lower plane (4w) of the nut (4) is centered on the axis. Assuming a circle inscribed in the contact surface, the radius of the inscribed circle is the radial distance between the line (4e) connecting the valley bottoms of the screws of the nut (4) and the axis of the nut. The washer fastening structure according to any one of claims 3 to 8, which has a dimension of at least 0.8 times the sum of twice the distance Ls and the distance Ls.
The washer fastening structure according to any one of claims 2 to 9, wherein the distance Ls is in the range of a length of 2 times or more and 4 times or less of the screw pitch p.
The washer fastening structure according to any one of claims 1 to 10, wherein the nut (4) is a flange nut.
A washer body (1b) having parallel first and second planes (1u, 1w) and a washer body (1b) penetrating and extending in a direction perpendicular to the first and second planes (1u, 1w). A washer (1) having a bolt hole (1h) to be formed, wherein the washer has an axis of the bolt hole (1h) and a radial direction perpendicular to the axis.
The washer body (1b) has a stress non-transmission space (1s) that opens into the bolt hole (1h) and extends in the radial direction in a vertical cross section including the axis of the washer (1).
A washer characterized in that the stress non-transmission space (1s) is a concentric annular shape centered on the axis of the bolt hole (1h).
The stress non-transmission space (1s) of the washer body (1b) is in the radial direction from the inner peripheral surface (1i) of the bolt hole of the washer body (1b) in the vertical cross section of the washer (1). Let Ps be the position of the stress non-transmission space (1s) farthest to the outside, and the distance L in the radial direction from the position Ps to the inner peripheral surface parallel to the axis of the bolt hole (1h) or an extension line thereof. But,
0.5p ≤ L ≤ 5.7p
(In the formula, the diameter of the bolt hole (1h) is R, and the units of R and p are mm.
When R is 1.9 or less, p is 0.2 and
When R is more than 1.9 and less than 2.4, p is 0.25.
When R is more than 2.4 and 3.7 or less, p is 0.35.
When R is more than 3.7 and 5.5 or less, p is 0.5.
When R is more than 5.5 and 7.5 or less, p is 0.75.
When R is more than 7.5 and 9.5 or less, p is 1.0.
When R is more than 9.5 and 13 or less, p is 1.25.
When R is more than 13 and 23 or less, p is 1.5.
When R is more than 23 and less than 34, p is 2.
When R is more than 34 and less than 40, p is 3.
When R is more than 40 and 150 or less, p is 4. )
12. The washer according to claim 12.
The direction from the second plane (1w) of the washer body (1b) toward the first plane (1u) is defined as an upward, upward or upward direction, and the opposite direction is defined as a downward, downward or downward direction.
In the vertical cross section of the washer (1), the stress non-transmission space (1s) is a first stress non-transmission space (11s) that also opens to the first plane (1u) of the washer body (1b). ,
The washer body (1b) extends below the first stress non-transmission space (11s) to an inner peripheral surface of the bolt hole (1h) parallel to the axis.
(Hereinafter, the washer fastening structure having the first stress non-transmission space (11s) is referred to as "aspect A".)
The washer according to claim 12 or 13.
In the washer (1) of the aspect A, in the vertical cross section, the boundary line (B3) between the washer main body (1b) and the first stress non-transmission space (11s) is the first plane (1u). ) To at least the region where the depth in the axial direction is 0.1 times the p, which is a stress concentration relaxation line composed of a curve or a combination of a curve and a straight line and having no corners. , The washer according to claim 14.
The washer (1) of the aspect A, in the vertical cross section of the washer (1).
The boundary line (B3) between the washer body (1b) and the first stress non-transmission space (11s) has a shape in which the washer body (1b) does not have the first stress non-transmission space (11s). In the stress distribution equivalent to Mieses formed on the washer body (1b) when a fastening force by a virtual nut is applied to the upper plane of the washer body (1b), the upper plane (1u) is assumed to be. The stress value equivalent to Mieses applied in the downward direction perpendicular to the upper plane (1u) from the position where is in contact with the first stress non-transmission space (11s) is used as a reference value, and the stress value equivalent to Mieses is 95% of the reference value. It is on the bolt hole (1h) side of the stress distribution curve of
The third boundary line (B3) between the washer body (1b) and the first stress non-transmission space (11s) is a curved line or a straight line with a curved line, and is a stress concentration relaxation line having no corners. , The washer according to claim 14 or 15.
In the vertical cross section of the washer (1), the first plane (1u) of the washer body (1b) extends to the inner peripheral surface (1i) of the bolt hole parallel to the axis of the bolt hole (1h). The washer body (1b) forms an eaves portion (1p) on the upper side of the first plane (1u), and the stress non-transmission space (1s) is formed on the lower side of the eaves portion (1p). The existing second stress non-transmission space (12s),
(Hereinafter, the washer fastening structure having the second stress non-transmission space (12s) is referred to as "aspect B").
The washer according to claim 12 or 13.
In the washer (1) of the aspect B, in the vertical cross section of the washer (1), the second stress non-transmission space (12s) is on the second plane (1w) side of the washer body (1b). The fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) is formed from the second plane (1w) of the washer body (1b). The rising part (Br) that extends upward at an angle within 20 degrees with respect to the axis direction and reaches a position where it comes into contact with a straight line forming an elevation angle of 20 to 25 degrees with respect to the axis, and an elevation angle of 20 to 20 to the axis. Includes a corner portion (Bc) connecting the straight lines forming 25 degrees and 65 to 70 degrees and positions in contact with each other, and a bolt hole inner peripheral end portion (Be) extending from the corner portion to the bolt hole inner peripheral surface (1i). , The washer according to claim 17.
The fourth boundary line (B4) between the washer body (1b) and the second stress non-transmission space (12s) in the vertical cross section of the washer (1) of the aspect B. ) Is a curved line or a straight line with a curved line and has no corners, and is a stress concentration relaxation line. However, the connection portion with the second plane (1w) does not have to be a stress concentration relaxation line. The washer according to 17 or 18.
The washer according to any one of claims 13 to 19, which satisfies 2p ≦ L ≦ 4p.
In a plan view of the washer (1) viewed from a direction perpendicular to the axis, the diameter of the circle inscribed in the outer periphery of the first plane (1u) of the washer body (1b) is D, and the bolt hole (1h). Any one of claims 13 to 20, where (D / 2) 2- (R / 2 + L) 2 ≧ k (R / 2) 2 (in the formula, k = 2.5), where R is the diameter of Washers listed in.
Claim that a part or all of the surface of the washer (1) is subjected to surface treatment for the purpose of rust prevention, abrasion resistance, lubricity improvement, slidability improvement, appearance improvement, decoration, or identification. The washer according to any one of 12 to 21.
22. The surface treatment is plating, plasma CVD coating, plasma PVD coating, vacuum deposition, resin coating, polymer coating, alumite, or manganese phosphate chemical conversion treatment, or a combination of two or more thereof. Washer.
The washer according to any one of claims 12 to 23, wherein the material of the washer (1) is selected from metal, nitride, carbide, oxide, composite resin, CFRP or hard resin.
The washer according to any one of claims 12 to 24, wherein the two planes of the washer (1) have a surface roughness of 50 μm or less and a flatness of 0.2 mm or less in arithmetic average roughness Ra.
It is characterized by processing and manufacturing washers (1) by pressing, cutting, grinding, cold, warm, hot pressing, casting, forging, injection molding, sintering, or a combination of these methods. The method for manufacturing a washer according to any one of claims 12 to 25.
The method for manufacturing a washer according to claim 26, wherein molding is performed using a mold, a cutting tool, a cutting tool, or a combination thereof.