TWI705202B - Double screw structure - Google Patents

Abstract

In the double screw structure 1 of the present invention, a first screw (S1) and a second screw (S2) with different leads are formed in the double screw portion, which has a locking function and sufficient strength of the screw portion. The screw portion includes a first screw (S1) and a special second screw (S2) composed of coarse screws having a standard pitch P. The second screw (S2) is continuously formed on the thread of the first screw (S1). The cross-sectional shape of the screw groove has the same or substantially the same shape as the first screw (S1), and has the same twisting direction, and is a self-contained lead with a predetermined multiple n of the standard pitch P (L=n*p ) A screw with a triangular cross-sectional shape and multiple screws with less than one screw.

Description

Double screw structure

The present invention relates to a double screw structure with locking function and the like. In more detail, the double screw structure (male screw) is a first screw (S1) with a triangular cross-sectional shape formed with threads, and a second screw (S1) formed on the threads of the first screw (S1). S2) Two kinds of structures. The second screw (S2) is a plurality of screws with a different lead (lead) from the first screw (S1), and is a double screw structure having the same triangular thread as the first screw (S1) with the same cross-sectional shape . The double screw structure relates to a double screw structure that can be used in fasteners and lead cam devices with sufficient strength and a locking function.

Regarding the fastening structure of a screw having a locking function, various structures have been proposed from the past. The general method is called a "double nut" fastening method. The tightening method is to tighten the nut 1 of the female screw on the screw part of the double screw structure (male screw), and then contact the nut 2 of the female screw with the nut 1 to tighten it to stretch A method in which force (axial force) acts between two nuts. The mutual fastening of the nut 1 and the nut 2 prevents the loosening of the screw due to the vibration or the like of the structure in which it is used. The "double nut" usually means that the nut 1 is a locking nut (a thin nut), and the nut 2 that is tightened later is a tightening nut (a thick nut).

As one of the techniques to improve the technology, it has been proposed to form screws with different pitches (for example, coarse-thread screws and fine-thread screws) in the screw portion (male screws), using nuts for coarse-thread screws and fine-thread screws. The nut is tightened, and the technology has a locking function due to the difference in the distance between the two. As a manufacturing method of the bolt used here, the manufacturing method of the multiple bolt which formed the coarse screw and the fine screw is known (for example, refer patent document 1). In addition, there is also known a related technology in which either one of a coarse screw and a fine screw is used as a locking bolt of a plurality of screws (for example, refer to Patent Document 2 and Patent Document 3).

In addition, in order to equalize the plastic deformation during rolling, that is, the rolling load, there have been proposed rolling screws including coarse-threaded screws having a standard first pitch and fine-threaded screws having a second pitch smaller than the first pitch. The related art of making the shape of the screw thread of the bolt (refer to Patent Document 4).

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3546211

[Patent Document 2] Japanese Patent Laid-Open No. 2003-184848

[Patent Document 3] Japanese Patent Laid-Open No. 2003-220438

[Patent Document 4] Japanese Patent Laid-Open No. 2010-014226

As explained above, the existing bolt with locking function as a double-screw structure is used in the screw part of the bolt including coarse-threaded and fine-threaded screws. The principle of the screw pitch of the nut of the coarse thread screw and the nut of the fine thread screw is different. That is, two nuts are tightened separately, and when the two screws are tightened, the tightening torque is different due to the difference in the screw pitch. The difference in torque is mainly used to prevent loosening. However, most of such bolts are bolts having a structure in which the screw portion is a fine screw in which the same triangular thread is provided on a coarse screw having a triangular cross-sectional shape.

The screw portion of the bolt has a structure in which a fine-pitch screw is formed on the thread of a coarse-pitch screw, and the pitch of the fine-pitch screw is small and the threads with shallow grooves become periodically formed protrusions (the cross-sectional shape is approximately triangular). As a result, the bolts including coarse-threaded screws and fine-threaded screws described in Patent Document 1 to Patent Document 4 have a small cross-sectional shape (area) of fine-threaded screws, and therefore, the strength during screw tightening is insufficient (shearing of threads). Destruction, insufficient allowable contact surface pressure, etc.). That is, the triangular cross-sectional area of the fine thread screw is small, so the strength of the screw portion is weakened. For example, if a large axial force is applied to a fine-pitch screw via a nut, since the shearing length of the fine-pitch screw (the length of the bottom side of the thread) is short, deformation or shear failure may occur. In addition, in the rolling die for manufacturing the screw, since the cross-sectional area constituting the triangle is small, there is a possibility that a part of the protrusion of the rolling die for forming the fine screw may be damaged. A rolling die with a defect in a part of the protrusion becomes a defective product, and an operation of replacing it with a new rolling die is required, which reduces the productivity of the bolt rolling operation.

On the other hand, the double screw structure (male screw) is formed with coarse-threaded screws with a standard pitch and a thread of the coarse-threaded screw having n times the standard pitch. The multiple screw structure of the lead coarse screw is also considered to have a locking effect due to the difference in the two leads. However, in the double screw structure, the height of the thread periodically changes. At a certain angular position, a continuous part of the thread with a low height is formed, and the volume of the thread (or the cross-sectional area of the cut surface) is smaller than The usual screws. Therefore, in the screw portion of the double screw structure, the area where the screwed nut engages (contacts) with its thread is small, and the strength of the screw portion (shear failure of the screw, contact surface pressure, etc.) may be insufficient. On the other hand, in lock bolts that include a double-screw structure, for example, in infrastructure equipment such as bridges, there is a demand for high strength in the screw part, and it is hoped that the development can be improved without using fine-threaded screws. Double screw structure with screw tightening strength.

The present invention was created to solve the above-mentioned existing problems, and achieve the following objectives.

The object of the present invention is to provide a double screw structure formed with a first screw of a general design specification and a special second screw, which can be used as a locking fastener with sufficient strength of the screw part, and the second screw is in the On the thread of the first screw, the lead is different from that of the first screw, and multiple screws are deformed.

Another object of the present invention is to provide a double screw structure, which can be used as a lead cam device for converting rotation into linear motion. The double screw structure is formed with the first general design specification 1 screw and a special second screw, the second screw is on the thread of the first screw, the lead is different from the first screw, and multiple screws are deformed.

In order to achieve the objective, the present invention adopts the following means.

The double screw structure of the present invention 1 is formed with two kinds of screws on the screw shaft. The double screw structure is characterized by including: a first screw (S1) formed on the screw shaft (3), and The cross-sectional shape of the thread is a screw with a pitch (P); and the second screw (S2) is a screw continuously formed on the thread, the cross-sectional shape is a triangular screw, and has the same twisting direction as the thread , And it is one or more screws that have a lead (Ln) of a predetermined multiple (n) of the pitch (P) of the thread.

The double screw structure of the present invention 2 is the present invention 1, characterized in that the predetermined multiple (n) is an integer multiple of the pitch (P).

The double screw structure of the present invention 3 is the present invention 1 or the present invention 2, characterized in that: in the second screw (S2), the lead (Ln) is twice the pitch (P) of the thread The number of the plurality of screws is two, and one screw is formed.

The double screw structure of the invention 4 is the invention 1 or the invention 2, characterized in that: in the second screw (S2), the lead (Ln) is 3 times the pitch (P) of the thread , The number of the plurality of screws is 3, and one or two of the screws are formed.

The double screw structure of the present invention 5 is like the present invention 1 or the present invention 2. It is characterized in that: in the second screw (S2), the lead (Ln) is 4 times the pitch (P) of the thread, the number of the plurality of screws is 4, and 2 are formed The screws.

The double screw structure of the present invention 6 is the present invention 1 or the present invention 2, characterized in that: the first screw (S1) and the second screw (S2) are located on the center line including the double screw structure On the cross-section of, the hill-shaped thread grooves appearing at specific angle positions are filled with base metal.

The double screw structure of the present invention 7 is the present invention 6, characterized in that the outer diameter of the valley is the effective diameter of the first screw (S1).

The double screw structure of the present invention 8 is the present invention 1 or the present invention 2, characterized in that: the first screw (S1) and the second screw (S2) are raw materials whose macroscopic fibrous structure is continuous along the thread Rolling screws flowing groundlessly.

The double screw structure of the invention 9 is the invention 1 or the invention 2, and is characterized in that the first screw (S1) is a metric coarse screw.

The double screw structure of the present invention 10 is the present invention 1 or the present invention 2, characterized in that: the double screw structure is that the screw shaft (3) is a bolt (81), including screwed into the first screw The first nut (82) of (S1) and the second nut (84) that is screwed into the thread of the second screw (S2) and has a triangular cross-sectional shape for tightening and fixing parts and parts Parts of the fastener (80).

The double screw structure of the invention 11 is the invention 1 or the invention 2, characterized in that: the double screw structure is that the screw shaft (3) is a lead cam (91), including the first screw (S1) Parts of the lead cam device (90) of the first cam follower (92) to be engaged and the second cam follower (94) to be engaged with the second screw (S2).

The double screw structure of the present invention includes a first screw (S1) and a second screw (S2). At each angular position in the circumferential direction of the axis of the screw shaft, a reference mountain shape or a reference mountain can be formed continuously or at regular intervals. Since the thread has a shape similar to the reference mountain shape, the strength of the screw portion can be improved. In addition, the double screw structure has increased the volume of the thread, increased the contact surface pressure applied to the nut, and improved the thread’s resistance compared with the existing locking bolts including coarse-threaded and fine-threaded screws. Resistance to shear failure stress. In addition, since the double screw structure of the present invention does not use conventional fine-threaded screws, it does not fill the thread grooves with, for example, molten tin during the immersion treatment for plating. As a result, it can also be used for fasteners of infrastructure equipment such as bridges that use large-diameter bolts with thickly plated threads.

1, 10, 11, 12, 20, 30, 100: double screw structure

2: Double screw part

2h: height of nut 53b

3: Screw shaft

50, 55, 60, 81: bolts

50a: head

51: Fixed side fixture member

52: Moving side fixture member

53, 62, 84, 120: 2nd nut

53a, 53b, 58: nut

54, 61, 82, 110: 1st nut

56: cushion

65: Sensor

70: Locking test device

71: Fulcrum

72: The first member

73: Heavy Hammer

74: Exciting point

75: The second member

80: Fasteners with lock nuts

83: conical surface

85: conical hole

86: Fastened component

90: Lead cam device

91: Lead cam

92: 1st cam follower

93: Servo motor

94: 2nd cam follower

101: small thread

102: The usual metric coarse thread

103: The line segment of the hill-shaped thread 101

104: The line segment of the thread 102 of the usual metric coarse thread

105, 130: Filling part

106: Contour

109: Centerline

121: straight part

131: effective diameter

132, 134, 135, 136, 137: outer diameter

B01: Locking bolt

B0, B11: Bolt

B11-1, B11-2: Bolt body

de: Part (the part that is the outer peripheral surface of the screw shaft and is flat when viewed in section)

D: Double screw rolling die

F: direction

F2: Exciting force

g ₀ : Screw groove of the first screw (coarse screw)

g ₁ , g ₂ , g ₁₁ , g ₁₂ , g ₂₁ : Screw groove for the second screw (the second screw with 3 times the lead)

g ₃₁ , g ₃₂ : Screw groove for the second screw (the second screw with 4 times the lead)

g ₄₁ : Screw groove for the second screw (2nd screw with 2 times the lead)

h: height of nut 53a

h ₁ , h ₂ , h ₃ , h ₄ , hn: spiral

L ₁ , L ₂ , L ₃ , L ₄ , Ln: lead

M: Screw raw material

Q1: The outline of the first screw

Q3-1, Q3-1', Q3-2, Q4-2, Q2-1: Contour line of the second screw

r: 1st thread

r _s , r _s ', r _s1 : the second thread

r _s2 : 3rd thread

W: axial load

θ: direction

Fig. 1 (a) and Fig. 1 (b) are diagrams showing the double screw structure of the present invention, Fig. 1 (a) is a side view, and Fig. 1 (b) is a front view.

2(a) and 2(b) are cross-sectional views cut by a plane passing through the screw shaft in order to explain the structure of the double screw portion of the double screw structure 10 of the first embodiment of the present invention, FIG. 2( a) is an explanatory diagram partially showing the cross-sectional shape of the double screw portion at the "0° angular position", and FIG. 2(b) is an explanatory diagram partially showing the cross-sectional shape of the double screw portion at the "90° angle position".

Figures 3(a) and 3(b) are for explaining the structure of the double screw portion of the double screw structure 11 as a modification of the double screw structure 10 of the first embodiment, which is cut by a plane passing through the screw shaft Fig. 3(a) is an explanatory diagram showing the cross-sectional shape of the double screw part at the "0° angle position", and Fig. 3(b) is a part showing the double screw part at the "90° angle position" Illustration of the cross-sectional shape.

4(a) and 4(b) are for explaining the structure of the double screw portion of the double screw structure 12, which is another form of the double screw structure of the first embodiment, and is cut by a plane passing through the screw shaft Fig. 4(a) is an explanatory diagram showing the cross-sectional shape of the double screw part at the "0° angle position", and Fig. 4(b) is a part showing the double screw part at the "90° angle position" Illustration of the cross-sectional shape.

Fig. 5 is a double screw structure 10, a double screw structure 11, a double screw structure 12, and a double screw structure including a coarse screw and three well-known screws of the first embodiment, partially showing the position of each angle A list of cross-sectional views of the cross-sectional shape of the double screw portion at each position, cut by a plane passing through the screw shaft.

Fig. 6 is a graph showing the relationship between each angular position and the area ratio with respect to the double screw structure shown in Fig. 5.

FIG. 7 is an explanatory diagram for explaining the filling state of each angular position in the double screw structure 11 of the first embodiment when the screw material is rolled using a rolling die.

FIG. 8 is a graph showing the relationship between the filling rate of the rolling die and the filling rate of the space in the double screw structure 11 of the first embodiment.

9(a) and 9(b) are cross-sectional views cut by a plane passing through the screw shaft in order to explain the structure of the double screw portion of the double screw structure 20 of the second embodiment of the present invention. An explanatory diagram showing the cross-sectional shape of the double screw portion at "0° angle position" and "90° angle position".

10 is a cross-section of the double screw structure 20 of the second embodiment and the double screw structure including the coarse screw and four known screws, partially showing the cross-sectional shape of the double screw portion at each angular position Figure.

FIG. 11 is a graph showing the relationship between each angular position and the area ratio with respect to the double screw structure 20 shown in FIG. 10.

FIG. 12 is an explanatory diagram for explaining the filling conditions at each angular position when the screw material is rolled by a rolling die in the double screw structure 20 of the second embodiment.

FIG. 13 is a graph showing the relationship between the amount of rolling dies and the filling rate of the space in the double screw structure 20 of the second embodiment.

14(a) and 14(b) are cross-sectional views cut by a plane passing through the screw shaft in order to explain the structure of the double screw portion of the double screw structure 30 of the third embodiment of the present invention. Represents "0° angle position" and "90° angle position" An explanatory diagram of the cross-sectional shape of the double screw part.

15 is a cross-section of the double screw structure 30 of the third embodiment and the double screw structure including the coarse screw and two known screws, partially showing the cross-sectional shape of the double screw portion at each angular position Figure.

Fig. 16 is a graph showing the relationship between each angular position and the area ratio with respect to the double screw structure 30 shown in Fig. 15.

Fig. 17 is a schematic diagram showing the outline of a test device for measuring the tensile strength of a screw including the double screw structure of the present invention.

FIG. 18 is a diagram showing the results of a tensile test of the double screw structure 11 which is a modification of the normal coarse screw and Embodiment 1 (see FIGS. 3(a) and 3(b)).

19 is a schematic diagram showing the outline of a test device for performing a "screw cutting torque comparison test" of a screw including the double screw structure of the present invention.

Fig. 20 shows a conventional coarse screw, a conventional lock bolt including a fine screw and a coarse screw, and a modification of Embodiment 1 (refer to Figs. 3(a) and 3(b)), namely, a double screw structure 11 is a histogram of the test results of screw cutting torque.

Figures 21 (a) and 21 (b) are diagrams showing the outline of a test device used to confirm the locking effect of screws. Figure 21 (a) is a front view schematically showing the main parts of the device. 21(b) is the AA cross-sectional view of FIG. 21(a) cut along the AA line.

Fig. 22 shows a normal coarse screw, a conventional lock bolt including a fine screw and a coarse screw, and a modification of Embodiment 1 (refer to Figs. 3(a) and 3(b)), namely, the double screw structure 11 Figure of the comparative test results of the locking effect.

Fig. 23 is a diagram showing a comparison test result of a conventional coarse screw and a modification of Embodiment 1 (refer to Figs. 3(a) and 3(b)), that is, the locking effect of the double screw structure.

Figure 24 (a) and Figure 24 (b) are examples of using the double screw structure for a fastener with a lock nut, Figure 24 (a) is a partial cross-sectional view, Figure 24 (b) is a screw Sectional view of the engagement between the cap and the double screw structure.

Fig. 25 is a conceptual diagram showing an example in which a double screw structure is used for a lead cam device.

Fig. 26 is a cross-sectional view of screwing a fastening nut to a specific angle position of a double screw structure (4 times lead 2 screws), which is to fill the thread space presented by two small hills with base metal ( Ditch) example.

Fig. 27 is a diagram showing a state in which a locking nut is screwed into the double screw structure of Fig. 26, and is a cross-sectional view at a specific angle position thereof.

Figure 28 is the application of Embodiment 4 to each of the angular positions of Embodiment 1 "3x lead 2 screws", "3x lead 2 screws modification" and "3x lead 1 screw" The cross-sectional shape of each angular position of the double screw structure.

Figure 29 is a cross-section of the double screw structure at each angular position of the "4-fold lead 2 screws" of the second embodiment shown in Figures 10 and 15 and the "double lead 1 screw" of the third embodiment shape.

Figures 30(a) and 30(b) are modified examples of the filling portion of the fourth embodiment, and Figure 30(a) is the use of base metal to fill the threaded space (grooves) presented by two small hills to the effective diameter An example, Figure 30(b) is to fill the space (gully) Examples up to a diameter smaller than the effective diameter.

Figure 31 (a) ~ Figure 31 (c) are modified examples of the filling part of the fourth embodiment, Figure 31 (a) is the use of base metal, the cross-sectional shape of the outer diameter is inclined (relative to the center line) to fill An example of a threaded space (gully) presented by two hills. Fig. 31(b) is an example of V-shaped landfill, and Fig. 31(c) is an example of convex-shaped landfill.

Hereinafter, each embodiment of the double screw structure of the present invention will be described based on the drawings. Fig. 1(a) and Fig. 1(b) show an embodiment of a double screw structure, Fig. 1(a) is a front view, and Fig. 1(b) is a side view.

[Double screw structure 1]

Hereinafter, first, the outline of the double screw structure of the present invention will be explained. The double screw structure 1 has a thread with a triangular cross-sectional shape on the outer circumference of the screw shaft 3. In this example, a standard pitch P (= lead L ₁ ) standardized according to the nominal diameter is formed as a metric helix having a coarse screw threads (hereinafter also referred to as "coarse screw threads") h 1 of the first screw (S1). On the thread of the first screw (S1), a screw having a helix h n having a lead L _n (=n*P) that is a predetermined multiple (n) times the pitch P of the coarse screw is formed 2 screws (S2). The second screw (S2) is a screw (thread and screw groove) that is continuously and spirally formed on the thread of the first screw (S1) and has a triangular cross-sectional shape. In addition, the spiral direction of the second screw (S2) is the same twist direction as the thread of the first screw (S1), and is a screw with a lead (nP) that is a multiple (n) of the pitch (P) of the thread Or multiple screws. However, to be precise, the second screw (S2) is one or more screws less than the original number of screws. That is, from the original multiple screws, one or more screws are removed from the number of the multiple screws (also referred to as "new multiple screws"). In addition, although one or more screws are removed from the original number of multiple screws, depending on the number of removed screws, there are cases where it is not multiple screws, but results in one screw.

In addition, the lead L _{1 of the} first screw (S1) is smaller than the lead L _{n of} the second screw (S2). The shape and pitch P of the first screw (S1) are determined by the relevant specifications of the screw (for example, International Standardization Organization (ISO)), and in this example are the standard specifications of the metric coarse screw. However, the pitch P of the first screw (S1) may be a screw having a pitch different from the standard specification. 1(a) and 1(b), regarding the double screw structure 1, only the double screw portion and its vicinity are shown, but the double screw structure 1 is formed on a screw shaft, a bolt ( For example, hexagonal bolts, hexagonal socket bolts, eyebolt, studbolt, anchor bolt, stop screw, wing bolt, U-bolt, ceiling bolt (ceiling bolt)) etc.

For example, when the double screw structure 1 is used as a double nut for locking, the first screw (S1) (metric coarse screw) is screwed into the first nut 82 (tightening screw) as a female screw. Cap), and screw a second nut 84 (locking nut) as a female screw to the second screw (S2) (refer to Figs. 24(a) and 24(b)). With the configuration described above, the first nut 82 screwed into the first screw (S1) generates a large tightening force, and is tightened by the second nut 84 as a lock nut. By so The lead angles of the two nut caps are different, which produces a locking effect. That is, the double screw structure 1 can give a large screw shaft 3 by tightening the fastened body with the first screw cap 82 of the first screw (S1) screwed into the double screw part 2 Preload. As a result, the fastened state can be maintained even when external force acts on the fastened member 86 from the axial direction.

In addition, the second screw (S2) of this example includes screws (threads and screw grooves) having the same triangular cross-sectional shape as the coarse-thread screws, and fine-thread screws are not used. Therefore, the double-screw structure 1 can increase the contact area between the thread and the nut, and the volume of the thread is also increased compared to the conventional bolts containing fine-thread screws. Therefore, the area to be engaged with the second nut can be increased, and the allowable shear failure stress of the thread and the allowable contact surface pressure can be increased. Therefore, insufficient strength of the screw portion will not occur. Furthermore, the second screw (S2) of this embodiment preferably has a lead that is a predetermined multiple or more of the lead of the first screw (S1), but it is considered that it is actually used as a double nut for general metal materials , The screw with a lead of 4 times or less is preferred. The reason is that if the lead of the nut screwed into the second screw (S2) is increased, the thread needs to be at least one turn, and the length of the nut in the axial direction is increased. Therefore, when manufacturing a nut with a tap, processing becomes difficult, so it is preferably 4 times the lead or less.

As described above, the embodiment of the first screw (S1) of the present invention is a metric coarse screw. The second screw (S2) is one or more screws less than the original number of screws. The inventors of the present invention aim to remove one screw from the second screw (S2) (multiple screws) formed on the coarse screw (first screw (S1)) based on the coarse screw (first screw (S1)) The above, and the double-screw structure 1 with reduced number is repeated Concentrate on research and development. As a result, the double screw structure of the present invention having both the strength improvement of the double screw portion 2 and the locking effect was discovered. Hereinafter, with regard to the double screw structure 1 of the present invention, each preferred combination of the first screw (S1) and the second screw (S2) as the double screw portion 2 will be described in detail.

[Embodiment 1] [Including coarse screw and "3x lead 2 screws" double screw structure]

Hereinafter, a specific description will be given using FIGS. 2(a) and 2(b). The double-screw structure of the first embodiment described in Figs. 2(a) and 2(b) is formed with a first screw (S1) including a thread and a screw groove on the double screw portion 2 of the screw shaft 3 . The thread is a standard "Metric Coarse Screw" (hereinafter also referred to as "Coarse Screw") prescribed by ISO (the International Organization for Standardization), and the first screw (S1 ). On the first screw (S1), screw in a nut which is a normal female screw for coarse metric thread. In addition, a second screw (S2) is formed on the thread of the first screw (S1) in such a manner that the thread appears to be chipped (walled). The second screw (S2) is a special screw, one is removed from the three screws, and the removed number of screws (threads and screw grooves) are not formed. That is, in this example, one screw is removed from the original three screws (hereinafter also referred to as "3x lead 2 screws").

Figures 2 (a) and 2 (b) are to illustrate the structure of the double screw structure 10 ("3 times lead 2 screws") of the first embodiment, cut with a plane passing through the center line of the screw shaft 3 Figure 2(a) shows the cross-sectional shape of the double screw portion 2 at the "0° angle position" of the double screw structure 10, and Figure 2(b) shows the double screw portion 2 at the "90° angle position" Section shape. The double screw structure 10 shown in FIGS. 2(a) and 2(b) is formed with a first screw (S1) as a metric coarse screw and a second screw with the same metric coarse screw as a reference chevron (S2). The second screw (S2) in this example is 2 screws (referred to as "3x lead 2 screws") by removing 1 from the original 3 screws. The first screw (S1) in this example is a metric coarse screw with a standardized pitch P (lead L ₁ =P). The second screw (S2) is two screws having a lead L ₃ (=3P) that is three times (integer multiple) of the pitch P of the metric coarse screw. The second screw (S2), which is the two screws, is formed by reducing the original three screws (hereinafter referred to as "known three screws") by one (removing one) in the first The screw on the thread of the screw (S1).

The metric coarse thread screw as the first screw (S1) is a screw with the same pitch P and lead L _1. Along the helix h ₁ , a screw groove g ₀ and a thread r (hatched line) are formed at a fixed pitch section). As the second screw (S2), the "3x lead 2 screws" (the gray part in Figure 2(a) and Figure 2(b) refers to the screw cap) is the lead L ₃ (=3P ), two screw grooves g ₁ and g ₂ are formed along the spiral line h ₃ . Furthermore, in the description of the first embodiment, for convenience of explanation, the cross-sectional shape of the screw groove g ₀ of the coarse screw is compared with the screw groove g ₁ and screw groove g ₂ of "3 times the lead 2 screws". The angular position at which the cross-sectional shapes overlap is described as the "0° angular position" in Fig. 2(a).

In Fig. 2(a) and Fig. 2(b), the first screw (coarse screw) S1 is a cross section of the first thread r with the pitch P (= lead L ₁ ) indicated by the contour line (solid line) Q1 A screw with a triangular shape. The second screw (S2) of "3 times lead 2 screws" is a screw with one thread removed from the known three screws. In other words, it is an outline (two-point chain line) that does not form a screw (groove). ) The so-called "new two screws" in the present invention indicated by Q3-1. The new two screws have a portion where two screw grooves g ₁ and a screw groove g ₂ are continuously formed at a fixed pitch, and one screw is not formed adjacent to the screw groove g ₂ (or screw groove g ₁ ) Part of the groove. That is, the new two screws are alternately formed at the portion (a portion that is the outer peripheral surface of the screw shaft portion and is flat in a cross-sectional view) de and a set of screw grooves g ₁ and screw grooves g ₂ 3 screws with lead L ₃ (=3P) produce 2 screws with variation. As mentioned above, the gray part shown in Fig. 2(a) and Fig. 2(b) refers to the thread screwed into the second nut of the second screw (S2) which is "3x lead 2 screws" Section shape.

At the "0° angular position" of FIG. 2(a), there is a first thread r (hatched portion) formed in a reference mountain shape (triangular shape) as an original coarse screw. The first thread r has a triangular reference mountain shape (triangular shape) formed continuously and regularly at intervals of a fixed pitch P. However, at the "90° angle position" in Figure 2(b), the peak of the first thread r, which is the base of the original coarse thread screw, appears to be shaved off. The hill-shaped second thread r _s of the first thread r. At the above-mentioned angular position, the second thread r _{s is} formed in a screw shape in which four mountains are continuous contour lines in a mountainous shape. That is, the first thread r that is the reference mountain shape (triangular shape) of the coarse screw is cut, the second thread r _{s is} reduced, and the shear failure stress of the thread is lower than the reference mountain shape (the original triangular shape). However, as will be described later, in the double screw structure 10 of the first embodiment, the "new multiple screws" as the second screw (S2) have locations where no screws (grooves) are formed regardless of the angular position ( 0° angle, 180° angle position, etc.), the original triangular mountain shape of the thread of the coarse screw is bound to remain.

The double screw structure 11 shown in Figs. 3(a) and 3(b) is a modification of the double screw structure 10 shown in Figs. 2(a) and 2(b), which is a double screw structure (" A cross-sectional view of the modified example of "3x lead 2 screws") 11. That is, the double screw structure 11 is a structure in which the angular phase of two screws of the double screw structure 10 is changed. Figures 3(a) and 3(b) are cross-sectional views cut by a plane passing through the screw shaft, and Figure 3(a) partially shows the cross-sectional shape of the double screw portion 2 at the "0° angle position" Fig. 3(b) is an explanatory diagram partially showing the cross-sectional shape of the double screw portion 2 at the "90° angular position". That is, the "3x lead 2 screws" shown in Figs. 2(a) and 2(b) is a screw that simply removes one screw from the original three screws, so the angular phase of the thread is variable. Therefore, the modification of the "3x lead 2 screws" shown in FIGS. 3(a) and 3(b) is a screw that changes the angular position of the two screws to equalize the arrangement of the two screws.

The "3x lead 2 screws" in the above-mentioned modification (the gray part of Fig. 3(a) and Fig. 3(b) refers to the cross section of the screw nut) is the lead L ₃ (=3P ) Screws. The screw has two screw grooves g ₁₁ and screw grooves g ₁₂ formed at equal intervals between the leads L ₃ and the "3 times lead 2" shown in Figure 2 (a) and Figure 2 (b) Two screws with different screws. That is, the deformation of the "3 times the lead 2 screws" is shown by the outline Q3-1', for example, between the screw groove g ₁₁ and the screw groove g _{12, and} between the screw groove g ₁₂ and the screw groove g ₁₁ , A portion where no screw groove is formed on the thread of the coarse screw (a portion that is the outer peripheral surface of the screw shaft and is flat in a cross-sectional view) de is formed.

The coarse screw is a screw with the same pitch P and lead L ₁ , and a screw groove g _{0 is} formed along the helix line h ₁ (if viewed from the nut, it is a thread g ₀ ). The "3x lead 2 screws (modified example)" shown in Figs. 3(a) and 3(b) are 2 screws with a lead L ₃ , which are formed along the spiral line h ₃ at predetermined intervals Two screw grooves g ₁₁ and screw grooves g ₁₂ (gray part). In the cross-sectional shape of the "0° angle position" and the "90° angle position" of the double screw structure 11, between the first thread r (hatched portion) and the first thread r of the reference mountain shape, Two hill-shaped second threads r _s ′ are formed in a mountainous shape, and the height of the second thread r _s ′ is lower than that of the first thread r. The small mountain chain shown in Fig. 2(b) has two mountains, and therefore, the shear failure strength is stronger than that of the four continuous mountains.

[Including coarse screw and "3 times lead 1 screw" double screw structure]

Figures 4(a) and 4(b) show the double screw structure 12 of the first embodiment. Fig. 4(a) is an explanatory diagram partially showing the cross-sectional shape of the double screw portion 2 at the "0° angular position", and Fig. 4(b) is a partially showing the cross-sectional shape of the double screw portion 2 at the "90° angle position" Illustration. Figures 2(a), 2(b), 3(a), and 3(b) show that the second screw (S2) is 2 screws with 1 removed from the original 3 screws, but the figure The double screw structure 12 shown in 4(a) and FIG. 4(b) is a structure obtained by removing two of them to form one screw. Therefore, no matter what the cross-sectional angle, there are still a lot of threads of coarse screw.

That is, the double screw structure 12 is formed with coarse screws having a pitch P (lead L ₁ =P), and a lead L ₃ (=3P) that is three times (integer multiple) of the pitch P of the coarse screw. ) 1 screw (hereinafter referred to as "3 times lead 1 screw"). In the cross-sectional views of Figs. 4(a) and 4(b), the coarse-threaded screws are triangular screws with a pitch P indicated by the contour line Q1. The above-mentioned "3 times lead 1 screw" is a screw that has not formed (removed) 2 screws among the "known 3 screws", and is a screw indicated by the outline Q3-2. The special one screw is a part where one screw groove g ₂₁ is formed, and a part where two screw grooves are not formed adjacent to the screw groove g ₂₁ (gray part) (as the outer peripheral surface of the screw shaft and A flat portion in a cross-sectional view) de alternately formed one screw of lead L ₃ (=3P). The coarse screw is one screw with the same pitch P and lead L ₁ , and a screw groove g ₀ and a thread r are formed along the spiral line h ₁ .

"One screw with 3 times the lead" is one screw with the lead L ₃ (3P), and one screw groove g ₂₁ (gray part) is formed along the spiral line h ₃ . At the "0° angular position" of FIG. 4(a), a cross-sectional shape of a double screw in which the first thread r (hatched portion) formed in a reference mountain shape is continuous is formed. In the cross-sectional shape of the "90° angle position" in FIG. 4(b), the first thread r, which is a reference mountain shape, and the second thread r _s (hatched part) of the two hills of mountain-like hills, are continuous. The height of the second thread r _s is lower than the first thread r.

FIG. 5 is a list of cross-sectional views showing the cross-sectional shape at each angular position of the screw ridge of the double screw portion 2 of the screw shaft 3. Fig. 5 is for each of the double screw structure 10, the double screw structure 11, and the double screw structure 12 when one or two screws are formed on a coarse screw, using the thread passing through the screw axis (center line) A partial cross-sectional view of the plane cut off. 6 is a graph showing the relationship between each angular position and the area ratio of the screw shaft of the double screw portion 2 of each screw shaft 3 shown in FIG. 5. Furthermore, the area ratio (%) in Figure 6 refers to the threaded The ratio (%) of the area of the original coarse screw having a triangular cross-sectional shape to the cross-sectional area of the double screw structure 10, the double screw structure 11, and the double screw structure 12 at each angle position. Fig. 7 is an illustration for explaining how the rolling material is filled in the recesses of the circular rolling die at each of the angular positions when the double screw structure 11 of the first embodiment is rolled. Figure. FIG. 8 is a graph showing the relationship between the amount of insertion at each angular position of the circular rolling die and the filling rate (%) when the double screw structure 11 of Embodiment 1 is rolled using the circular rolling die. From the above relationship, it can be understood that the double screw structure 11 of the first embodiment can be smoothly rolled.

As described above, the double screw structure 10, the double screw structure 11, and the double screw structure 12 shown in FIGS. 2(a) and 2(b) to 4(a) and 4(b) include The first screw (coarse screw) (S1), and the "3x lead 2 screws" as the second screw (S2) (refer to Figure 2 (a) and Figure 2 (b), Figure 3 (a) and Figure 3(b)) or "3 times lead 1 screw" (refer to Figure 4(a) and Figure 4(b)). Figures 2(a) and 2(b) to 4(a) and 4(b) illustrate the structure of the double screw structure 10, the double screw structure 11, and the double screw structure 12, respectively. The cross-sectional shape of each thread at 0° angle position" and "90° angle position". Based on FIGS. 5 and 6, another angular position of the double screw structure 10, the double screw structure 11, and the double screw structure 12 will be described. Figures 5 and 6 also show the double screw structure including coarse-threaded screws and "known 3 screws", and the coarse-threaded screws and new multiple screws ("3 times lead 1 Modifications of "3 screws", "3x lead 2 screws" and "3x lead 2 screws") A diagram comparing the double screw structure 10, the double screw structure 11, and the double screw structure 12.

That is, FIG. 5 is a diagram showing the relationship between the angular position of every 30° in the circumferential direction of the axis of the screw shaft 3 on which the double screw portion 2 shown in FIG. 1(a) is formed and the cross-sectional shape of the double screw portion 2. 6 is a graph showing the area ratio of the angular position per 30° in the circumferential direction of the axis of the screw shaft 3 (refer to FIGS. 1(a) and 1(b)) and the cross-sectional area of the double screw portion 2. As shown in FIG. 5, the double screw structure repeatedly exhibits the same combined cross-sectional shape at every predetermined period. For example, in the "3x lead 2 screws" shown in Figures 2(a) and 2(b), the two leads are combined for each cycle of 3 times the pitch of the coarse screw It is presented by repeating the same shape. FIG. 5 is a diagram showing the area of the cross-sectional area of the double screw portion 2. Fig. 6 is a diagram showing the area ratio of the cross-sectional area of the double screw portion 2, where the sum of the cross-sectional area of the triangular thread at each angular position and the cross-sectional area of the reference mountain-shaped coarse screw is set to 100%, A diagram showing comparisons at each of the angular positions.

As shown in Figure 5, the double-screw structure including the coarse-threaded screw and the "known 3 screws" has the same size and spacing as the coarse-threaded screw and the "known 3 screws", so they are in a predetermined angular position. The mountain shape generates interference, and there is an angular position where the mountain shape hardly remains (refer to the left end of FIG. 5). The double screw structure may deform from the angular position where the mountain shape does not remain and the vicinity thereof, thereby causing insufficient strength of the screw shaft portion and the screw portion. For example, the double screw structure is formed at an angular position other than "0° angular position" and "180° angular position" Above, especially at the "90° angle position", the height of the thread is lower than the reference mountain-shaped thread, and the hill-shaped thread is a cross-sectional shape of a double screw that continuously exhibits in the axial direction. Also, from the "60° angle position" to the "120° angle position", the area ratio is reduced to 42% or less. That is, the double screw structure including the coarse screw and the "known three screws" has angular positions where the strength of the double screw portion is insufficient.

In contrast, in the double screw structure 10, the double screw structure 11, and the double screw structure 12 of the first embodiment, there are places where no screw groove is formed (0°) on the new multiple screws as the second screw (S2). Angle, 180° angle position, etc.) to increase the volume of the thread, so that no standard mountain shape remains at any angle. For example, the double screw structure (coarse screw and "3x lead 2 screws") 10 at the "90° angle position" is also formed as a double screw portion 2 with a standard mountain-shaped thread at regular intervals The cross-sectional shape and area ratio have also increased to about 56%. In addition, the double screw structure (coarse screw and "3 times lead 1 screw") 12 at the "90° angle position" is also formed as a double screw portion 2 with a standard mountain-shaped thread per mountain The cross-sectional shape and area ratio have also increased to about 78%. In addition, the double screw structure (coarse screw and "3-fold lead 2 screw" modification) 11 does not have a continuous angular position of the standard mountain-shaped thread, but it is formed to be continuous or at regular intervals. The cross-sectional shape of the double screw portion 2 having a standard mountain-shaped thread has an area ratio covering all angular positions and becomes a stable large value of about 70% to about 78%. That is, the double screw structure 10, the double screw structure 11, and the double screw structure 12 are formed so that the strength of the screw portion is sufficient.

Regarding the rolling processing method of the double screw structure, the double screw The structure (coarse screw and the modification of "3x lead 2 screws") 11 will be described as an example. Fig. 7 shows the "0° angle position", "90° angle position", and "180° angle position" when the screw rolling die D is inserted into the screw material M and the double screw structure 11 is rolled. Figure of the filling result. The above-mentioned angular position is a portion where the shape of the double screw portion is significantly different in the double screw structure 10, and is shown as a representative example. In addition, FIG. 8 is a graph showing the relationship between the amount of insertion and the filling rate in the screw rolling process. As shown in Fig. 7 and Fig. 8, the following process has been confirmed: at each angular position, the screw material M is plastically deformed at approximately the same filling rate, and the rolling surface formed on the screw rolling die D is reliably filled In the space between the rolled surface of the screw material M, the double screw portion 2 is continuously rolled.

[Embodiment 2]

Figure 9 (a) and Figure 9 (b) shown in the second embodiment of the double screw structure 20 is a first screw (S1) (metric coarse screw) formed on the screw shaft 3, and formed on the thick The second screw (S2) (2 screws) with a lead L ₄ (=4P) 4 times the pitch P on the thread of the screw. The 2 screws are reduced by 2 (2 in the middle of the 4) from the general 4 screws (thread and screw groove) (hereinafter referred to as "well-known 4 screws") to form 2 screws The new multiple screws (hereinafter referred to as "4-fold lead 2 screws") are a double screw structure 20 in which a double screw portion 2 is formed.

Figures 9(a) and 9(b) are cross-sectional views for explaining the structure of the double screw structure 20 of the second embodiment, and Figure 9(a) is a partial view of the double screw portion 2 at the "0° angle position" An explanatory diagram of the cross-sectional shape, Figure 9(b) is a partial representation An explanatory diagram of the cross-sectional shape of the double screw portion 2 at the "90° angular position". Fig. 10 shows the double screw structure 20 of the second embodiment and the double screw structure including the threads of coarse screw and "well-known 4 screws" (general 4 screws), partially showing each angle position A cross-sectional view of the cross-sectional shape of the double screw portion at each position. Fig. 11 shows the area ratio (%) of the double screw portion 2 at each angular position for the double screw structure of the second embodiment and the double screw structure including coarse thread screws and four known screws Graph. Fig. 12 is an explanatory diagram for explaining the filling state of each angular position of the double screw structure of the second embodiment.

Figures 9(a) and 9(b) show the "0° angle position" and "90° angle position" of the double screw structure 20 including coarse thread screws and "4 times lead 2 screws" Section 2 of the cross-sectional shape. The double screw structure 20 includes a coarse screw with a pitch P (lead L ₁ =P), and a lead L ₄ (=4P) that is 4 times (integer multiple) of the pitch P of the coarse screw. The thread of the screw. However, the two screws mentioned above are the "two screws with 4 times the lead" except for the "well-known four screws". The coarse screw is one screw with the same pitch P and lead L ₁ , and a screw groove g ₀ (or thread) is formed along the spiral line h ₁ . "4 times lead 2 screws" are screws with lead L ₄ (=4P), and two screw grooves g ₃₁ and g ₃₂ are formed along the spiral line h ₄ . Furthermore, in the description of the second embodiment, for convenience of explanation, the cross-sectional shape of the screw groove g ₀ of the coarse screw is compared with the screw groove g ₃₁ and screw groove g ₃₂ of "4 times lead 2 screws". The angle position where the cross-sectional shape overlaps is set to "0°" for description.

In Figs. 9(a) and 9(b), the cross-sectional shape of the coarse screw is a triangular screw with a pitch P indicated by the outline Q1. The "4x lead 2 screws" is a screw that removes 2 of the "well-known 4 screws". "4 times lead 2 screws" are screws indicated by outline Q4-2 without screw groove g ₃₁ and screw groove g ₃₂ (the gray part refers to the nut screwed into it). "4 times lead 2 screws" is provided between the screw groove g ₃₁ and the screw groove g _{32, and} between the screw groove g ₃₂ and the screw groove g ₃₁ , where a screw is not formed (as the screw shaft part). 2 screws whose lead L ₄ (=4P) on the outer peripheral surface is flat in a cross-sectional view). At the "0° angular position" shown in FIG. 9(a), a standard double screw shape is formed, that is, a first thread r and a screw groove formed in a reference mountain shape are continuously formed. At the "90° angular position" shown in FIG. 9(b), the height of the first thread r and the thread of the reference mountain shape is lower than the second thread r _s1 and the third thread of the hill shape of the first thread r r _s2 is a double screw shape forming a continuous contour line of 2 mountains.

In the description of Figs. 9(a) and 9(b), the "0° angle position" and "90° angle position" in the double screw structure 20 have been described, but based on Figs. 10 and 11, The double screw structure 20 is further described. Figures 10 and 11 are a comparison of a double screw structure including coarse-threaded screws and "well-known four screws" (general four screws), and the coarse-threaded screws of the second embodiment and the "4 times lead 2 A diagram for comparison of the double screw structure 20 of the "strip screw". Fig. 10 is a diagram showing the relationship between the angular position of every 30° in the circumferential direction of the axis of the double screw portion shown in Fig. 1(a) and the cross-sectional shape of the double screw portion 2. FIG. 11 is a graph showing the area ratio of the angular position of every 30° in the circumferential direction of the axis of the screw shaft 3 to the cross-sectional area of the double screw portion 2. The area ratio of the cross-sectional area of the double screw The sum of the cross-sectional area in one cycle of the reference mountain-shaped screw is set to 100%, and it is shown in comparison with the sum of the cross-sectional area in one cycle at each position of each angular position.

The double-screw structure 20 including coarse-threaded screws and "well-known four screws" has the same size and spacing of the mountain-shaped screws and the "well-known four screws", so the mountain-shaped structure will cause interference at a predetermined angle position. And there is a position where there is almost no mountain shape left. The double screw structure 20 may be deformed in the thread from the angular position where the mountain shape does not remain and the vicinity thereof, and the strength of the screw portion may be insufficient. For example, the double screw structure 20 is formed into a cross-sectional shape of a double screw with a low height at the "60° angular position". Therefore, at the angular position, the strength of the screw portion tends to be significantly insufficient. Also, regarding the ratio of the cross-sectional area to each angular position, when the cross-sectional area of the "0° angle position" is set to 100%, "60° angle position", "180° angle position", and "300° angle position" The cross-sectional area of (not shown) is significantly reduced to approximately 35%, and the strength of the double screw portion is insufficient.

In contrast, the double screw structure (coarse screw and "4 times lead 2 screws") 20 of the second embodiment is on "4 times lead 2 screws", as shown in Figure 10, there is The part where the screw groove is not formed, so that the volume of the thread is increased, and there is no remaining mountain shape. For example, regardless of the angular position of the double screw structure 20, the cross-sectional shape of the double screw portion 2 in which the reference mountain-shaped thread always appears continuously or at predetermined intervals is formed. In addition, when the area ratio of the "0° angle position" of the double screw structure 20 is set to 100%, as shown in FIG. 11, the area ratio of the "60° angle position", "180° angle position", etc. becomes About 68%. Therefore, the double screw structure 20 is set continuously or at regular intervals. The cross-sectional shape of the double screw portion 2 in which the thread of the reference mountain shape must be formed is formed so that the strength of the screw portion is sufficient.

Fig. 12 shows the "0° angle position", "60° angle position", and "90° angle position when the double screw structure 20 is rolled into the screw rolling die D and inserted into the screw material M. The figure of the filling result on ". The above-mentioned angular position is a portion where the shape of the double screw portion is significantly different in the double screw structure 20, and is shown as a representative example. In addition, FIG. 13 is a graph showing the relationship between the filling amount and the filling rate in the screw rolling process. As shown in Figures 12 and 13, the following process has been confirmed: at each angular position, the screw material M is plastically deformed at approximately the same filling rate, and the rolling surface formed on the screw rolling die D is reliably filled In the space between the rolled surface of the screw material M, the double screw portion 2 is continuously rolled.

Furthermore, the double screw structure may also be a double screw structure including coarse screw and 4 times lead 1 screw or 4 times lead 3 screws, the 4 times lead 1 screw or 4 times lead The lead of 3 screws has a lead of 4 times the pitch P of the coarse screw, and contains screw grooves with one or three fewer screws.

[Embodiment 3]

The double screw structure 30 of the third embodiment shown in Figs. 14(a) and 14(b) is formed on the screw shaft 3, including a metric coarse screw (the first screw), and the lead L ₂ is thick The double screw structure 30 of the double screw portion 2 of the new multiple screws (hereinafter referred to as "two-fold lead 1 screw") of the number of screws is twice the pitch P of the screw. That is, the "2 times lead 1 screw" means that the first screw (S1) is a coarse screw, and the second screw (S2) has twice the lead of the coarse screw and is removed from the original two screws 1 screw of 1 piece.

Figures 14(a) and 14(b) show the "0° angle position" and "90° angle position" of the double screw structure 30 including coarse screw and "2x lead 1 screw" (second screw (S2)) The cross-sectional shape of the double screw part 2 at the angle position". For example, the double screw structure 30 includes coarse-threaded screws with pitch P (lead L ₁ =P) and "2 times lead 1 screw", and the "2 times lead 1 screw" is the lead L ₂ ( =2P) is twice the pitch P of coarse-threaded screws, and includes 1 screw whose number is reduced by 1 screw from "2 well-known screws" (general 2 screws). The coarse screw is one screw with the same pitch P and lead L ₁ , and a screw groove g ₀ (or thread) is formed along the spiral line h ₁ . "2 times the lead 1 screw" is 1 screw of the lead L _{2 and} a screw groove g _{41 is} formed along the spiral line h ₂ . Furthermore, in the description of the third embodiment, for the convenience of description, the angle at which the cross-sectional shape of the screw groove g ₀ of the coarse screw and the cross-sectional shape of the screw groove g ₄₁ of "2 times lead 1 screw" overlap Set the position to "0°" for explanation.

In Figs. 14(a) and 14(b), the coarse screw is a screw with a pitch P indicated by the contour line Q1. "2 times lead 1 screw" is a screw that has not formed one screw among the "known two screws", and is formed with one screw indicated by the outline Q2-1, which is provided in the screw groove g There is no screw formed between ₄₁ and screw groove g ₄₁ (a part that is the outer peripheral surface of the screw shaft and is flat in a cross-sectional view) of one screw of lead L ₂ (=2P). Fig. 14(a) shows the cross-sectional shape of the double screw portion 2 at the "0° angle position" of the double screw structure 30, and Fig. 14(b) shows the double screw at the "90° angle position" of the double screw structure 30 Section 2 of the cross-sectional shape. At the "0° angular position", the first thread r (or screw groove) formed in a reference mountain shape is continuously formed. At the "90° angle position", the double screw shape of the contour line Q2-1 is formed, that is, the first thread r having a reference mountain shape is formed so that the height of the thread is slightly lower than the first thread r , The second thread r _{s1 of the} medium thread, and the third thread r _{s2 of the} hill-shaped thread formed so that the height of the thread is lower than the second thread r _s1 .

Regarding the double screw structure 30 of the third embodiment, the "0° angular position" and the "90° angle position" have been described, but the double screw structure 30 will be further described based on FIGS. 15 and 16. . Figures 15 and 16 show a double screw structure including coarse-threaded screws and "well-known two screws", and a double-screw structure including coarse-threaded screws of the second embodiment and "two-fold lead 1 screw" Figure 30 for comparison. 15 is a diagram showing the relationship between the angular position of every 30° in the winding direction of the screw shaft 3 and the cross-sectional shape of the double screw portion 2. 16 is a diagram showing the area ratio of the angular position of the double screw portion 2 per 30° to the cross-sectional area of the double screw portion 2. The ratio of the cross-sectional area of the double screw portion 2 is that the sum of the cross-sectional area in one cycle of the coarse screw whose cross-section is a triangular thread, that is, the reference mountain-shaped thread is set to 100%, and the ratio of the cross-sectional area of each angular position The sum of the cross-sectional area of one cycle is compared and shown.

The double-screw structure including the coarse-threaded screw and the "known 2 screws" has the same size and spacing as the ridges of the coarse-threaded screws and the "known 2 screws", so the ridges interfere at a predetermined angular position and exist. Almost no mountain-gata position remains. The double screw structure may not leave the angular position of the mountain shape The screw thread is deformed and the strength of the screw is insufficient. For example, the double screw structure is formed into a cross-sectional shape of a double screw with continuous low threads at the "180° angular position" and the vicinity of the thread (see 180° in FIG. 15). Therefore, at the angular position, the strength of the screw portion tends to decrease significantly. Also, regarding the ratio of the cross-sectional area to each angular position, when the "0° angular position" is set to 100%, the cross-sectional area is from the "120° angular position" to the "220° angular position" (not shown) It is significantly reduced to about 40% or less, and the strength of the double screw part is insufficient.

In contrast to this, the double screw structure 30 of the third embodiment has a portion where a screw groove is not formed on the "two-fold lead 1 screw", which increases the volume of the thread and does not cause a situation where no chevron is left. . The double screw structure 30 is formed in a cross-sectional shape of the double screw portion 2 in which a reference mountain-shaped thread is always present continuously or at predetermined intervals regardless of the angular position. Therefore, the strength of the screw portion is sufficient. Moreover, when the area ratio of the "0° angular position" of the double screw structure 30 is 100%, the area ratio is approximately 65% or more regardless of the angular position.

[Tensile strength of double screw structure]

Regarding the double screw structure of the first to third embodiments, the tensile strength was confirmed. FIG. 17 is a schematic diagram showing the outline of a test device for measuring the tensile strength of a screw including the double screw structure of the present invention, and a tensile test is performed using the test device. The data shown in Fig. 18 shows the double screw structure 11 (refer to Fig. 3(a) and Fig. 3) as a normal coarse screw, as a modification of "3 times the lead 2 screws"). (b)) Graph of tensile test results. again Furthermore, the tensile strength is mainly related to the shear fracture stress of the thread in the axial direction of the double screw structure.

On the bolt 50 including the head 50a and formed with the double screw structure 11, the second nut 53 and the first nut 54 are screwed, and the first nut 54 and the second nut 53 are made into double nut Form the way to be tightened. For example, the first nut 54 is a nut of a female screw formed with a coarse screw. In addition, the second nut 53 is a nut formed with a female screw having a plurality of new screws. The bolt 50 is inserted into the bolt hole formed in the fixed side jig member 51 and the movable side jig member 52, and the lower surface of the head 50 a of the bolt 50 abuts the fixed side jig member 51. The moving-side clamp member 52 is moved in a direction away from the fixed-side clamp member 51 (the arrow F direction), and a load is applied to the bolt 50. In other words, a tensile load is applied between the head 50a of the bolt 50 and the first nut 54 and the second nut 53, and the tensile strength of the bolt 50 is measured (see FIG. 17). The measurement is performed until the screw shaft of the bolt 50 is broken or the thread is cracked, and the nut falls off.

The double screw structure 11 (a modification of Embodiment 1) is a representative example, and the result of the tensile test will be further described. In FIG. 18, the bolts (for example, hexagonal bolts) B0 of the normal coarse-threaded screws formed with the metric coarse-threaded screws whose "Nominal of the screw" is M16 and the bolts ( For example, hexagonal bolt) B11 is the result of a tensile test. In the above description, the second screw nut 53a and the first nut 54 are screwed into the double screw structure 11 as a double nut as the bolt body B11-2 is shown in FIG. 18 in. In addition, the second nut 53b and the first nut 54 are screwed into the double nut as a double nut. The heavy screw structure 11 is shown in FIG. 18 as a bolt body B11-1. In addition, the nut 53a is a standard height, ie, a height h (for example, 13 mm) of "M16 normal hexagonal nut (JIS B 1181)". The nut 53b is a nut formed to have a height 2h (for example, 26 mm) that is twice the height h (for example, 13 mm) of the nut 53a.

In FIG. 18, the vertical axis represents the tensile load (KN), and the horizontal axis represents the stroke (mm) of the tensile test. As a result, it can be confirmed that the tensile strength of the bolt body B11-1 and the bolt body B11-2 in which the dual structure 11 is formed shows 90% or more of the tensile strength of the normal bolt B0 of M16. That is, it can be confirmed that the strength of the double screw structure 11 formed on the bolt body B11-1 and the bolt body B11-2 does not cause problems in practical applications. In addition, it was confirmed that the strength of the double screw structure 11 sufficiently exceeded the guaranteed load (48,700N) of the strength class 4.8 of the M16 coarse screw. In addition, in the above-mentioned embodiment, the double screw structure 11 as a modification of the first embodiment is described as a representative example. However, it was confirmed that the same test can be obtained in the double screw structure of other embodiments. result.

[Nut screw cutting torque test]

With respect to the double screw structure of the first to third embodiments, a screw cutting torque test was performed to confirm the strength of the double screw structure. 19 is a schematic diagram showing the outline of a test apparatus for performing a comparative test of screw cutting torque (maximum tightening torque) of a screw including the double screw structure of the present invention. Figure 20 shows a normal coarse screw, a conventional lock bolt including a fine screw and a coarse screw, and a double including the "3x lead 2 screws" (modified example) of the modification of the first embodiment Column of test results of screw cutting torque of screw structure 11 State chart.

As shown in Fig. 19, in the test device, a nut 58 is screwed into a bolt 55 inserted into a block 56, and the nut 58 is tightened until the tightening torque does not rise, using a torque wrench (torque Wrench) (not shown) measures the maximum tightening torque at this time (refer to Fig. 19). In addition, in the nut screw cutting torque test, in order to compare and confirm the strength of the double screw structure, the usual bolt B0 formed with metric coarse-threaded screws, and existing lock bolts including coarse-threaded and fine-threaded screws B01. The bolt B11 formed with the double screw structure 11 as a modification of the first embodiment was tested, and the maximum tightening torque value was compared.

As shown in FIG. 20, regarding the maximum tightening torque value, the second screw (S2) as the double screw structure 11 is not inferior to the bolt B0 of a normal coarse screw. That is, it has been confirmed that the bolt B11, which is the double-screw structure 11, can be tightened with a normal coarse screw nut when it is tightened with a female screw, which is a nut with threads of a new plurality of screws. Tighten the bolt B0 of a normal coarse-threaded screw until the maximum tightening torque is approximately the same. In addition, if the height (thickness) of the nut on which the threads of the new screws are formed is increased, the maximum tightening torque is increased. In addition, regarding the double screw structure 11, compared with the conventional lock bolt B01 including a fine screw and a coarse screw, it corresponds to the "fine screw nut" (49Nm) for the fine screw The ``coarse thread nut'' (162Nm) for coarse thread screws and the ``multiple nut'' (218Nm~293Nm) of the new multiple screws corresponding to the nut of the coarse thread screw are all increased by the value of the maximum tightening torque. Therefore, it can be confirmed that the maximum tightening torque value of the double screw structure 11 has increased. In addition, in the above-mentioned embodiment, it is a double as a modification of the first embodiment. The screw structure is described as a representative example, but it was confirmed that the same test result can be obtained in the double screw structure of other embodiments.

[Locking effect of double screw structure]

Regarding the double screw structure 11 of the first embodiment to the third embodiment, the locking effect was confirmed. Figure 21 (a) and Figure 21 (b) shows a test device (Nissei (Nissei) Co., Ltd. (Headquarters: Yamanashi, Japan) to confirm the locking effect of the screw including the double screw structure of the present invention Figure of the outline of ). Fig. 21(a) is a front view schematically showing the main part of the test device, and Fig. 21(b) is an A-A cross-sectional view taken along the line A-A of Fig. 21(a). Figure 22 shows a normal coarse screw, a conventional lock bolt (B01) including a fine screw and a coarse screw, and a modification of Embodiment 1 (as a "double screw with 3 times the lead and 2 screws" A graph showing the results of a comparative test of the locking effect of the double screw structure 11 (B11) of the modified example of the structure"). FIG. 23 is a diagram showing the results of a comparative test of the locking effect between a normal coarse screw and the "modified example of the double screw structure" of the first embodiment.

The lock test device 70 includes a first member 72 that swings with a fulcrum 71 as a fulcrum, a weight 73 provided at a position spaced apart from the fulcrum 71 by a predetermined amount, a second member 75 including an excitation point 74 and the like. The first member 72 and the second member 75 are coupled by the bolt 60, the first nut (tightening nut) 61, and the second nut (tightening nut) 62. Symbol 65 is a sensor for measuring the axial force of the bolt 60, and the axial force is displayed on a measuring device body not shown. The first nut 61 and the second nut 62 constitute a so-called double nut. After the shaft portion of the bolt 60 is inserted into the bolt hole of the first member 72 and the bolt hole of the second member 75, the first nut 61 and the second nut 62 are tightened and fixed to obtain a predetermined axial force. The excitation force F2 of the prescribed conditions (frequency: 713 min ^-1 , amplitude: 11 mm) is applied to the excitation point 74 of the lock test device 70, and the second member 75 is swung in the direction of arrow θ. The sensor 65 measures this How does the axial force of the bolt 60 change?

The bolt B0 formed with the normal coarse screw of M16, the conventional lock bolt B01 including the coarse screw and the fine screw, and the bolt B11 formed with the double screw structure 11 were subjected to the lock test. The bolt B0 formed with the coarse threaded screw is fixed as a double nut by the first nut and the second nut formed with the coarse threaded female screw. The conventional lock bolt B01 is fastened and fixed using a second nut formed with a female screw with fine teeth and a first nut formed with a female screw with coarse teeth as a double nut. The bolt B11 formed with the double screw structure 11 uses the first nut (tightening nut) 54 of the female screw formed with coarse threads and the second nut (tightening nut) of the female screw formed with a plurality of new screws. Use a nut) 53 as a double nut to fasten and fix.

As shown in FIG. 22, even if the bolt B11 formed with the double-screw structure 11 is excited, the axial force hardly decreases, and the locking effect is maintained. In contrast, the bolt B0 of a normal coarse-threaded screw has a large axial force immediately after excitation, and the locking effect cannot be maintained. In addition, in the conventional locking bolt B01, a slight decrease in the axial force was observed immediately after the vibration, but the locking effect was maintained thereafter. Next, after tightening the bolt B0 of the coarse screw before excitation and the bolt B11 of the double screw structure 11 with the same axial force, an excitation test is performed under the conditions to further confirm the locking effect .

The results are shown in FIG. 23. Even if the bolt B11 formed with the double-screw structure 11 undergoes excitation, the axial force hardly decreases, and the locking effect is maintained. On the other hand, the axial force of the bolt B0 of the coarse-threaded screw drops immediately after the excitation. That is, the double screw structure 11 can be confirmed to have a locking effect. In addition, in the locking test, the double screw structure 11, which is a modification of the first embodiment, is used as a representative example. However, it is confirmed that the same can be obtained in the double screw structure of other embodiments. The test results.

In the double screw structure 1, the structure of the thread and the screw groove is equivalent to a coarse screw, and compared to the conventional double screw including a fine screw, it has a rigid shape, and the strength is maintained. At the time of tightening, the first nut screwed on the first screw is in a tightened state of a normal coarse screw, and therefore has a structure that particularly improves the strength compared to a fine screw. A load is applied to the structure fastened by the double-screw structure 1, even if an axial force is generated on the double-screw structure 1, the shaft is maintained by the first nut tightened on the first screw Xiangli. In addition, in the double screw structure 1, in addition to the friction force generated by the tightening force between the first nut and the second nut, there is a difference in the lead of the first screw and the second screw, and both The two nuts cannot rotate at the same time, which can produce a locking effect. As a result, the double-screw structure 1 can increase the axial force (torque) compared with the conventional double-screw structure including the locking of fine screw.

In addition, if it is a conventional double-screw bolt that includes coarse-threaded screws and fine-threaded screws, plating treatment, especially thicker plating treatment, will fill the screw grooves of fine-threaded screws. Applied to double screws containing fine thread screws. For example, if a thick-film plating such as high corrosion-resistant molten tin plating is applied to a fine-threaded screw, the plating will gather on the fine-threaded thread and fill the screw groove. However, the double screw structure 1 does not use fine-threaded screws, so there is no possibility of filling the screw grooves, so this kind of plating can be used. As a result, the bolts and screw shafts including the double-screw structure 1 can be plated to increase their value and function. In addition to the existing machinery and electrical fields, they can also be used in the construction and civil engineering fields that require corrosion resistance. .

[Embodiment 4]

As for the double screw structure of the embodiment described in FIGS. 5 and 6, FIG. 10 and FIG. 11, FIG. 15 and FIG. 16, a graph showing the relationship between each angular position (screw angle) and area is used As explained, at a certain angular position, the area ratio (%) is small. Therefore, when the "Tensile Strength of the Double Screw Structure" test is performed on each of the above-mentioned double screw structures using the test device of FIG. 17, shear failure occurs from the portion where the area ratio (%) is small. Even if the area ratio (%) is small, there is no problem with the mechanical design strength. However, if the allowable shear failure stress in the design is exceeded, the shear failure occurs first from the portion with a small area ratio (%). Fig. 26 is a partial cross-sectional view of screwing a fastening nut into a specific angular position of a double screw structure.

The type of the first nut (tightening nut) 110 in this example is a metric coarse nut. The example shown in FIG. 26 shows the cross section of the double screw structure 100 at a certain angle (the 90° cross section of the "3x lead 2 screws" shown in FIG. 5) on the double screw structure 100 and the first 1 Section of the nut 110. If the first nut 110 is tightened, the reaction force from the fastened body (not shown) will affect the double screw structure The body 100 is loaded with an axial load W. At the above-mentioned angular position, if the screw is tightened until shear failure occurs, at the position of the line segment (cross-sectional shape) 103 of the hill-shaped thread 101, shear failure occurs first. The line segment 103 is parallel to the center line 109 of the double screw structure 100. The line segment 103 is shorter than the line segment 104 of the thread 102 of a coarse screw having a normal size (cross-sectional area). Therefore, when the axial load W from the first nut 110 (tightening nut) equally applies a load to each thread, shear failure occurs first from the portion of the line 103 of the hill-shaped thread 101.

Even if the length of the first nut 110 in the axial direction is extended, shear failure occurs locally from the portion of the line 103 of the hill-shaped thread 101. Therefore, in the double screw structure 100 of the fourth embodiment, in order to avoid the shear failure of the hill-shaped thread 101, the space (groove) of the two hill-shaped threads 101 arranged in the axial direction is formed to fill the space (grooves) of the two hill-shaped threads 101 arranged in the axial direction using base metal. Section (the gray section in the figure) 105. As a result, the line segment 103 of the hill-shaped thread 101 is integrated with the next hill 101 to extend, and becomes approximately the same length as the line segment 104 of the thread 102 of a coarse screw of a normal size. Therefore, even if a load of the axial load W is applied to the double screw structure 100 on the hill-shaped thread 101, shear failure will not occur from the portion of the line 103 first.

Fig. 27 is a diagram showing a cross-sectional shape when a locking nut is screwed into a double screw structure (two screws with a 4-fold lead). That is, the locking nut 120 is a nut screwed into two screws of 4 times the lead as the double screw structure 10, and is another nut of the metric coarse screw cap. As shown in FIG. 26, the two hill-shaped threads 101 in the shape of a mountain are filled by the filling part 105. No. 2 nut (locking nut) 120 Since the filling portion 105 is arranged, it cannot be engaged with the two hill-shaped threads 101 in the shape of a mountain, so a straight portion (cross section) 121 is provided, that is, a circular hole with a spiral is provided. At the angle position (60° shown in FIG. 10) of the double screw structure 10 of this example, the double screw structure 10 and the second nut (locking nut) 120 and two mountain-shaped hills The shaped thread 101 is substantially not engaged.

However, since the tightening force is shared by the first nut 110 shown in FIG. 26, there is no problem. The function of the second nut 120 is not a tightening force but a nut that exerts the locking function of the first nut 110, so that the second nut 120 will not be sheared and broken. Furthermore, when it is determined that the strength of the shear fracture stress of the first nut 110 and the second nut 120 is insufficient in design, the thickness of the nut may be increased. Figure 28 is the application of this embodiment 4 to the embodiment 1 shown in Figure 5 "3 times lead 2 screws", "3 times lead 2 screws modification" and "3 times lead 1 screw" The cross-sectional shape of the double screw structure 10, the double screw structure 11, and the double screw structure 12 at each angular position. FIG. 28 is a diagram of a cross-sectional shape when the filled portion 105 is filled with base metal in the valley of the two hill-shaped thread 101 described above. Similarly, Fig. 29 shows the double screw structure at each angular position of the "4x lead 2 screws" of the second embodiment shown in Figs. 10 and 15 and the "2x lead 1 screw" of the third embodiment. The cross-sectional shape of the body 20.

[Modification of Embodiment 4]

In the modified example of the fourth embodiment described above, in the cross-sectional view, the contour line 106 of the outer peripheral surface of the filling portion 105 appears as a straight line parallel to the center line 109 of the double screw structure 100. However, the filling method of the filling portion 105 is not limited to the above-mentioned method. Figure 30 (a) In the double screw structure 100, the filling portion 130 is used to fill up to the position of the effective diameter 131 of the first screw (S1) constituting the double screw structure 100. That is, it is an example in which the space between two small hill-shaped threads 101 is filled up to the effective diameter 131 of the first screw (S1), that is, the outer peripheral surface. The diameter of the outer diameter (part of the cylindrical surface) 132 of the filling portion 130 is the same diameter as the effective diameter 131. FIG. 30(b) is an example in which the double screw structure 100 is filled up to an outer diameter (a part of the cylindrical surface) 134 smaller than the effective diameter 131 by the filling portion 130. In addition, the effective diameter refers to the diameter of a virtual cylinder where the width of the screw groove is equal to the width of the thread.

FIG. 31(a) is an example of filling in the double screw structure 100 such that the outer diameter 135 of the filling portion 130 becomes a slope. That is, the shape line of the outer diameter shown in the cross section of the filling portion 130 is a diagonal line and forms an acute angle with the center line 109. FIG. 31(b) is a diagram of the double screw structure 100 where the outer diameter 136 becomes a V-shaped V slope and is filled with the filling portion 130. That is, the shape line of the outer diameter appearing in the cross section of the filling portion 130 becomes a V-shaped line whose center is the most concave portion. FIG. 31(c) is a diagram of the double screw structure 100 where the outer diameter 137 is a convex portion and filled with the filling portion 130. The shape line of the outer diameter shown in the cross section of the filling part 130 is a convex line whose center is the most convex part. Furthermore, when the double screw structure 100 is rolled, when the outline of the outer diameter is a convex arc or ellipse, plastic deformation becomes easy, and the rolling workability is excellent. . Therefore, the life of the rolling roll for rolling these double screw structures is also long.

[Other embodiments]

The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Needless to say, changes can be made without departing from the purpose and spirit of the present invention. For example, it can also be a double screw structure that includes a combination of two screws (the first screw and S1) and two screws with a 4-fold lead (the second screw (S2)), and two screws with a 3-fold lead (the second screw). A double screw structure with a combination of 1 screw (S1)) and 4 times the lead 2 screws (second screw (S2)). In other words, the double screw structure only needs to be capable of forming a reference mountain shape or a thread similar to the reference mountain shape at each angular position in the circumferential direction of the axis of the screw shaft portion continuously or at predetermined intervals.

In addition, in the above-mentioned embodiment, the lead of the first screw (S1) and the second screw (S2) is described as an integer multiple of the lead of the coarse screw, but it may not be an integer multiple. For example, the second screw may have a lead that is a multiple of 3.1 times that of the coarse screw. In addition, the first screw may have a lead that is a multiple of 1.1 times that of the coarse screw. In other words, the double screw structure only needs to be capable of forming a reference mountain shape or a thread similar to the reference mountain shape at each angular position in the circumferential direction of the axis of the screw shaft portion continuously or at predetermined intervals.

In addition, in the above-mentioned embodiment, the double screw structure is described as being formed by a round rolling die and a flat die using rolling processing, but it may be selected from cutting processing and injection molding. Forming processing, 3D printing (three-dimensional modeling; 3D printing) processing, metal powder injection molding (Metal Injection Molding: MIM) processing, lost wax casting (Lost-wax casting) and other processing. However, the formation of threads by rolling processing does not cut the metal flow lines inside the metal structure by rolling processing. Therefore, the macroscopic fiber structure flows continuously along the screw surface. Structurally, it has the characteristics of high tensile strength and fatigue strength as screws.

[Application example 1]

Figure 24 (a) and Figure 24 (b) are examples of using the double screw structure for a fastener with a lock nut, Figure 24 (a) is a partial cross-sectional view, Figure 24 (b) is a screw Sectional view of the engagement between the cap and the double screw structure. The fastener 80 with a lock nut is an example of clamping the fastened member 86. In the screw part of the shaft part of the hexagonal bolt, the "coarse screw" and "3x lead 2 screws" shown in Figure 2 (a) and Figure 2 (b) are formed (refer to Figure 2 (a) and Figure 2(b)). The first nut 82 is screwed into the "coarse screw". The thread (helix h ₁ ) of the first nut 82 is a normalized normal thread. In this example, a conical surface 83 is formed integrally with the first nut 82 at one end of the first nut 82. In addition, the second nut 84 is screwed into the "3 times lead 2 screws" (helix h ₃ ). Since the second nut 84 is screwed into the "3 times the lead 2 screws", it is longer than the lead of the first nut 82 (consistent with the pitch P), and therefore, the amount of advancement for each revolution is large.

A tapered hole 85 is formed at one end of the second nut 84. When the first nut 82 is screwed in, the tapered surface 83 is in contact with the tapered hole 85 of the second nut 84, and the friction force is used to securely clamp by taper engagement. In addition, as long as the first nut 82 is turned and screwed in, it can be rotated and driven at the same time, so it is not necessary to screw in as a lock nut The second nut 84. The reason is that since the lead of the second nut 84 is longer than the pitch P of the first nut, the first nut 82 only needs to be screwed in, and the second nut 84 is rotated and clamped.

[Application example 2]

FIG. 25 is a front view showing an example in which a double screw structure is used for the lead cam device 90. In the above-mentioned embodiment, a metric coarse-threaded screw is used as a screw for description. It is an example in which a double screw structure formed with two kinds of threads and screw grooves with different pitches and leads is used as the lead cam 91 . The first cam follower 92 is engaged with the "coarse screw" (helix h ₁ ). In addition, the second nut 84 is screwed into the "3 times lead 2 screws" (helix h ₃ ). The second cam follower 94 is engaged with a plurality of screw grooves. When the lead cam 91 is rotationally driven by the servo motor 93, since the first cam follower 92 and the second cam follower 94 have different amounts of advancement per one revolution, they are used to rotate Convert the movement into the required linear motion. The required amount of movement is realized by the number of revolutions of the servo motor 93, the pitch of the "coarse screw", and the size of the lead of the "3x lead 2 screws". Therefore, the so-called double screw structure in the present invention is a steering cam.

In the above embodiment, the thread is described using a metric coarse-thread screw, but the same thread may have a triangular cross-sectional shape and standardized Whitworth screw, unified standard screw, fine-thread screw, etc. Therefore, in the double screw structure of the present invention, the so-called "screws with a standard pitch (P)" formed on the outer circumference of the cylindrical shaft are not limited to metric coarse-threaded screws, but can be said to be a reference The thread is formed with a thread of substantially or approximately the same shape Screws with thread grooves.

[Industrial availability]

The double screw structure of the present invention can be used for mechanical, electrical, construction, civil engineering, aerospace, aerospace, mechanical, electrical, construction, civil engineering, aerospace, aerospace, mechanical, electrical, construction, civil engineering, aerospace, and In various industries such as automobiles, railways, and ships.

10: Double screw structure

de: Part (the part that is the outer peripheral surface of the screw shaft and is flat when viewed in section)

g ₀ : Screw groove of the first screw (coarse screw)

g ₁ , g ₂ : Screw groove for the second screw (the second screw with 3 times the lead)

h ₁ , h ₃ : helix

L ₁ , L ₃ : lead

Q1: The outline of the first screw

Q3-1: The outline of the second screw

r: 1st thread

Claims (11)

A double screw structure, two types of screws are formed on a screw shaft. The double screw structure is characterized by comprising: a first screw (S1) formed on the screw shaft (3) and formed with a threaded cross section A screw with a triangular shape and a pitch (P); and a second screw (S2), which is continuously formed on the thread, has a triangular cross-sectional shape, and has the same twisting direction as the thread, and is The number of screws having a lead (Ln) that is a predetermined multiple (n) of the pitch (P) of the thread is less than one screw. In the double screw structure described in item 1 of the scope of patent application, the predetermined multiple (n) is an integer multiple of the pitch (P). The double screw structure described in item 1 or item 2 of the scope of patent application, wherein in the second screw (S2), the lead (Ln) is twice the pitch (P) of the thread, The number of the plurality of screws is two, and one screw is formed. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein in the second screw (S2), the lead (Ln) is 3 times the pitch (P) of the thread, The number of the plurality of screws is 3, and one or two of the screws are formed. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein in the second screw (S2), the lead (Ln) is 4 times the pitch (P) of the thread, The number of the plurality of screws is 4, and 2 of the screws are formed. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein the first screw (S1) and the second screw (S2) are in a cross section including the center line of the double screw structure In this, the hill-shaped thread grooves appearing at a specific angle position are filled with base metal. In the double screw structure described in item 6 of the scope of patent application, the outer diameter of the valley is the effective diameter of the first screw (S1). The double-screw structure described in item 1 or item 2 of the scope of patent application, wherein the first screw (S1) and the second screw (S2) are raw material whose macroscopic fibrous structure is continuously along the thread Flowing rolled screws. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein the first screw (S1) is a metric coarse screw. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein the double screw structure is used to tighten and fix parts and parts The parts of the fastener (80) include the screw shaft (3) as the bolt (81), the first nut (82) screwed into the first screw (S1), and the second screw A second nut (84) with a screw (S2) and a triangular cross-sectional shape of the thread. The double screw structure described in item 1 or item 2 of the scope of patent application, wherein the double screw structure is a part of the lead cam device (90), and includes the screw shaft (3) as the lead cam ( 91). A first cam follower (92) engaged with the first screw (S1), and a second cam follower (94) engaged with the second screw (S2).

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