JP5427804B2 - Wheel nut wrench - Google Patents

Description

  The present invention relates to a wheel nut wrench.

In an automobile, an L-shaped wheel nut wrench for attaching / detaching a wheel is mounted as an in-vehicle tool. The wheel nut wrench generally uses carbon steel as a material, and forms a nut fitting part to be fitted to the nut in a plurality of processes by hot forging, and machine the plane and cylindrical part of the nut fitting part by machining. Finishing is performed by bending the shaft (handle part) from a predetermined position and further quenching the whole (Patent Document 1).
In addition, for the purpose of reducing the weight of the product and reducing the cost, a technique has been proposed in which a wheel nut wrench is integrally formed using a hollow steel pipe (Patent Document 2).

JP 2001-219380 A JP-A-62-2236676 Japanese Patent No. 4436887

  However, when a wheel nut wrench is integrally formed using a steel pipe as described above, the nut fitting portion needs to be formed by expanding the steel pipe with a press. There was a problem that the strength of the nut fitting portion was insufficient. In addition, in order to secure the opening strength of the nut fitting part, a ring-shaped member (auxiliary steel pipe) is inserted into the tip of the steel pipe before forming, and manufacturing is performed so as to compensate for a reduction in plate thickness and insufficient strength by simultaneous forming. Although (patent document 3) is also proposed, since another member is used and the molding process is complicated, the cost becomes high. Furthermore, when a bending stress and a torsional stress are applied to the nut fitting portion, there is a possibility that the ring-shaped member and the steel pipe tip end are peeled off. In addition, in the case of an L-shaped wheel nut wrench, a strong bending torsional stress is also applied to the bent portion. Therefore, in order to ensure the strength of this portion, a high-strength material is used, the outer shape of the steel pipe is enlarged, A wheel nut wrench that needs to increase the thickness and achieves weight reduction and cost reduction of the product has not been put to practical use.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a wheel nut wrench that is inexpensive and lightweight and has high strength.

In order to solve the above problems, the present invention employs the following means.
The wheel nut wrench of the present invention comprises a hollow steel pipe, a handle portion, and a nut fitting portion that is formed integrally with the handle portion on one end side of the handle portion and has a nut fitting hole inside, And a folded flange portion that is folded outward from the front end of the nut fitting portion is formed integrally with the nut fitting portion on the outer peripheral surface side of the nut fitting portion. It is characterized by that.

  Moreover, it is good also as a structure which the outer peripheral surface of the said nut fitting part and the inner peripheral surface of the said folding | returning flange part are closely_contact | adhering.

  The inner diameter may be gradually reduced from the nut fitting portion toward the handle portion side.

  The steel pipe is formed by bending, and the nut fitting portion is provided on one end side of the handle portion via a bent portion, and the bent portion extends along the length direction of the bent portion. In addition, a plurality of ribs that protrude radially outward from the outer peripheral surface may be provided at predetermined intervals in the circumferential direction.

  According to the present invention, the handle portion and the nut fitting portion are integrally formed, and the flange portion that is folded outward from the tip of the nut fitting portion is formed integrally with the nut fitting portion. Therefore, compared with the case where the nut fitting portion and the folded flange portion are separate members, the strength against bending torsional stress in the nut fitting portion can be increased. In addition, an inexpensive material can be used and the weight can be reduced.

Moreover, since the outer peripheral surface of a nut fitting part and the inner peripheral surface of a return | turnback flange part are closely_contact | adhering, the intensity | strength by the side of the opening of a nut fitting part can be raised.
In addition, since the inner diameter gradually decreases from the nut fitting portion toward the handle portion, bending torsional stress does not concentrate on the portion (boundary portion) between the nut fitting portion and the handle portion. .
In addition, by providing a plurality of ribs that extend along the length direction at the bent part between the nut fitting part and the handle part, sufficient strength against bending torsional stress related to the bent part is secured. can do.

The figure which shows the whole structure of the wheel nut wrench which is one Embodiment of this invention. The fragmentary sectional view which shows the whole structure of a wheel nut wrench. The figure which shows the shape of the fitting hole of a nut fitting part. The figure which shows the shape of the fitting hole of a nut fitting part. Sectional drawing of a bending part (sectional drawing in alignment with CC line of FIG. 2). The fragmentary sectional view of a wheel nut wrench. The figure which shows the example of direction of the fitting hole with respect to a handle | steering-wheel part. The figure which shows the example of direction of the fitting hole with respect to a handle | steering-wheel part. The fragmentary sectional view which shows a return | turnback flange part. The perspective view which shows the structure of the conventional wheel nut wrench. The fragmentary sectional view which shows the fitting state of the conventional wheel nut wrench. The figure which shows the load-elongation curve at the time of applying tensile force to an electric-welded pipe. (A)-(e) is sectional drawing which shows the manufacturing process of a wheel nut wrench. Sectional drawing which shows the manufacturing process of a wheel nut wrench.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

  FIG. 1 is a diagram showing an overall configuration of a wheel nut wrench according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing the overall configuration of the wheel nut wrench. 3 and 4 are views showing the shape of the fitting hole of the nut fitting portion. FIG. 5 is a cross-sectional view of the bent portion. 6-8 is a figure which shows the example of direction of the fitting hole with respect to a handle | steering-wheel part. FIG. 9 is a partial cross-sectional view showing the folded flange portion.

  As shown in FIGS. 1 and 2, the wheel nut wrench 1 of this embodiment is an L-shaped tool for an automobile in which a handle portion 2, a bent portion 3, and a nut fitting portion 4 are integrally formed. A nut fitting portion 4 is provided on one end side of the handle portion 2 via a bent portion 3. This wheel nut wrench 1 has an outer diameter of 19 mm, a tube wall thickness of about 2 mm, and is formed by using a hollow long mild steel tube having a predetermined length, specifically, an inexpensive electric sewing tube. Is.

The nut fitting portion 4 is formed with a hexagonal nut fitting hole 5 (FIG. 2) having a predetermined length (depth) in the axial direction to be fitted to the wheel nut. The nut fitting hole 5 is formed by expanding the diameter using a jig that makes a part of the shaft hole 6 of the electric sewing tube 6 a hexagonal opening. The direction of the hexagonal nut fitting hole 5 with respect to the extending direction of the handle part 2 is arbitrary, and the extending direction of the handle part 2 and one corner of the nut fitting hole 5 coincide as shown in FIGS. The direction in which the handle portion 2 extends and one side of the nut fitting hole 5 may coincide with each other as shown in FIGS.
Here, the length of the opposite side of the nut fitting hole 5 is about 21 mm, and the outer diameter of the nut fitting portion 4 is about 30 to 31 mm.

On the outer peripheral surface 4b side of the nut fitting portion 4 of the present embodiment, the folded flange portion 7 is formed such that the front end side of the main body 1A is folded from the opening end 5a of the nut fitting hole 5 toward the bent portion 3 side. Is provided. The inner peripheral surface 7a of the folded flange portion 7 is in close contact with the outer peripheral surface 4b of the nut fitting portion 4, and there is no gap between them. The length L along the axial direction of the folded flange portion 7 is about 5 to 6 mm.
The thickness t on the opening end side of the nut fitting portion 4 provided with the folded flange portion 7 is about 3.4 to 3.7 mm.

  The outer shape of the nut fitting portion 4 is not particularly limited as long as the dimensional accuracy of the nut fitting hole 5 can be secured. For example, the outer shape reflecting the hexagonal shape of the nut fitting hole 5 as shown in FIG. As shown in FIG. 4, the outer shape may be a substantially circular shape in sectional view regardless of the shape of the nut fitting hole 5.

  Further, the wheel nut wrench 1 of the present embodiment has a reduced outer diameter from the nut fitting portion 4 to the handle portion 2 through the L-shaped bent portion 3. Along with this, the diameter of the inner shaft hole 6 is gradually reduced from the end on the nut fitting hole 5 side to the end on the handle part 2 side so as to follow the outer dimension of the bent portion 3. Thus, it is formed in a tapered shape. When the wheel nut wrench 1 is used, the bending torsional stress applied to the root portion of the nut fitting portion 4, that is, the boundary portion between the nut fitting portion 4 and the bent portion 3 is reduced.

  A plurality of convex ribs 31 extending in the axial direction and projecting outward in the radial direction are provided on the outer peripheral surface 3b of the bent portion 3 at predetermined intervals in the circumferential direction. The plurality of ribs 31 have the highest height in the central portion in the axial direction of the bent portion 3, and become lower from the central portion toward the nut fitting portion 4 side and the handle portion 2 side. As shown in FIG. 5, the cross-sectional shape of the bent portion 3 is a cross-sectional shape that can increase the strength against torsional stress when the wheel nut wrench 1 is used.

  In addition, although the wheel nut wrench 1 of this embodiment is a tool which exhibits a substantially L shape, it may have a shape other than this, for example, a T shape or a cross shape.

  A conventional wheel nut wrench 500 as shown in FIGS. 10 and 11 has a structure in which the difference in outer diameter between the nut fitting portion 504 and the bent portion 503 is large. When a force W for loosening the nut 505 is acted by such a wheel nut wrench 500, a bending stress W2 and a torsional stress W2 act from the nut fitting portion 504 as a starting point. In this case, there is a possibility that the nut fitting portion 504 or the boundary portion between the nut fitting portion 504 and the bent portion 503 may be deformed by bending torsional stress. However, as in the present embodiment, an extreme change in outer diameter between the nut fitting portion 4 and the bent portion 3 is eliminated, and a plurality of ribs 31 are provided on the bent portion 3, so that the bending twist applied during use is reduced. Strength against stress can be increased.

In addition, by providing the folded flange portion 7 integrally with the nut fitting portion 4, it is possible to eliminate the lack of strength due to the thinning of the tube wall when the nut fitting hole 5 is formed. Further, since it is not necessary to use a mild steel pipe having a thick pipe wall as a whole, the weight can be reduced. Moreover, since it forms integrally, there is no possibility that the folding | returning flange part 7 may peel from the nut fitting part 4, and sufficient opening strength is ensured.
Furthermore, in this embodiment, an electric sewing tube is used as the material of the wheel nut wrench. For this reason, a high strength wheel nut wrench can be obtained without cost.

FIG. 12 is a diagram showing a load-elongation curve when a tensile force is applied to the electric resistance welded tube.
When a tensile force (load) X is applied to the electric sewing tube, the elongation Y changes linearly to the elastic point A in proportion to the load. When the tensile force is increased beyond the elastic point A, it enters the plastic deformation region from the elastic deformation region and reaches the yield point B. Thereafter, a slight load decrease occurs, and the yield elongation occurs from the point C under the decreased substantially constant load. When the yield elongation is finished, the maximum load is reached at point D. When the point D is reached, a part of the ERW pipe is constricted, the load is reduced, and the elongation is increased, thereby breaking at the point E. Since the wheel nut wrench 1 of the present embodiment is formed in a region close to the point D (maximum load point), the breaking strength as a wheel nut wrench is larger than that of the conventional one, eliminating the lack of strength while reducing weight. It has a structure that can be done.

Next, the torsional strength accompanying the expansion of the outer diameter of the wheel nut wrench will be examined.
In principle, if the base metal diameter is increased to increase the torsional strength of the steel pipe, the thickness will decrease, but the polar section modulus (Zp) that affects the torsional strength will be increased accordingly. Therefore, it is possible to increase the torsional strength exceeding the thickness reduction.
As a specific example, consider a case where a steel pipe having an outer diameter of 19 mm, an inner diameter of 15 mm, and a tube wall thickness of 2 mm is expanded to an outer diameter of 23 mm, an inner diameter of 19.8 mm, and a tube wall thickness of 1.6 mm.

であり、 The polar section modulus Zp before diameter expansion is

And

である。 The polar section modulus Zp after diameter expansion is

It is.

  Assuming that the torsional torque applied to each steel pipe before and after diameter expansion is assumed to be the value shown below, the shear stress τ applied to the steel pipe:

となり、 The shear stress applied to the steel pipe before diameter expansion is

And

となる。 The shear stress applied to the steel pipe after diameter expansion is

It becomes.

  Therefore, as a conclusion, by expanding the diameter of the steel pipe, the torsional strength can be increased by about 30% compared to the case before the diameter expansion.

Next, a method for manufacturing the wheel nut wrench of this embodiment will be briefly described.
FIGS. 13A to 13E and FIG. 14A are cross-sectional views showing a manufacturing process of a wheel nut wrench.
FIG. 13F is a cross-sectional view corresponding to DD in FIG.
FIG. 14B is a cross-sectional view corresponding to EE in FIG.
As shown in FIG. 13A, an electric resistance welded tube (soft steel tube) 50 having a predetermined diameter is prepared as a base material. In this embodiment, an electric resistance sewing tube having a diameter of 19 mm and a wall thickness of 2 mm is used.

  Next, as shown in FIG. 13B, one end portion 50a of the electric sewing tube 50 is bent and deformed outward in the radial direction.

  Next, as shown in FIG. 13C, one end portion 50a of the electric resistance welded tube 50 that is curved and deformed radially outward is deformed along the outer peripheral surface 50b. In this way, the flange portion 7 is formed by folding back one end side of the electric sewing tube 50.

  Next, as shown in FIG. 13 (d), by inserting a taper-shaped jig (not shown) from the opening end 51 on the flange portion 7 side to the inside of the base material, The electric sewing tube 50 is deformed to increase the diameter.

  Next, as shown in FIGS. 13 (e) and 13 (f), a nut fitting (not shown) having a hexagonal outer shape in cross-sectional view is inserted from the opening end 51 on the flange portion 7 side. The hole 5 is formed, and the nut fitting portion 4 is produced at the opening end 51 on the flange portion 7 side of the electric sewing tube 50.

  Next, as shown in FIGS. 14A and 14B, a plurality of ribs 31 are formed in a predetermined region along the axial direction of the electric sewing tube 50 from the nut fitting portion 4 side. Specifically, a plurality of ribs 31 are formed in a tapered portion whose inner diameter is reduced from the nut fitting portion 4.

  Next, the electric sewing tube is bent at a predetermined angle using a pipe bending apparatus (not shown), a pipe bender, or the like. When the electric sewing tube 50 is bent, it is bent from the substantially central portion in the axial direction of the region where the plurality of ribs 31 are formed, so that the present embodiment presents a substantially L shape as shown in FIGS. The wheel nut wrench 1 is completed.

According to the present embodiment, the following effects can be obtained.
(1) A wheel nut wrench 1 having a nut fitting portion 4 integrally formed at the distal end portion of a wheel nut wrench main body 1A formed by bending a steel pipe into an L shape, and the outer side of the nut fitting portion 4 being opened Since the folded flange portion 7 is formed integrally with the portion, even a wheel nut wrench formed of a steel pipe has high strength, particularly high opening strength at the opening of the hexagonal head, and is inexpensive. A lightweight wheel nut wrench 1 can be obtained.
(2) Since the nut fitting portion 4 and the folded-back flange portion 7 are formed in close contact with each other, the wheel nut wrench 1 having a high opening strength at the opening of the hexagonal head can be obtained.
(3) Since the cross-sectional diameter is gradually changed from the nut fitting portion 4 toward the L-shaped bent portion 3 of the wheel nut wrench body, bending torsional stress is applied to the root portion of the nut fitting portion 4. There is no concentration.
(4) Since the convex rib 31 is formed in the bending part 3 along the longitudinal direction, sufficient strength can be ensured against bending torsional stress applied to the bending part 3.

ERW material: STKM11A (carbon steel pipe for machine structure)
Diameter: 19mm
Tube wall thickness: 1.6-1.8mm
Torsional stress: 226 N · m
Hex bolt compatible: Nut fitting hole opposite side length: 21m

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  DESCRIPTION OF SYMBOLS 1 ... Wheel nut wrench, 2 ... Handle part, 4 ... Nut fitting part, 3 ... Bending part, 3b, 4b, 50b ... Outer peripheral surface, 5 ... Fitting hole, 5a, 51 ... Open end, 7 ... Flange part, 7a ... Inner peripheral surface, L ... Length, 31 ... Rib, 50 ... ERW pipe (mild steel pipe)

Claims (4)

A wheel nut wrench comprising a hollow steel pipe, and having a handle portion, and a nut fitting portion formed integrally with the handle portion on one end side of the handle portion and having a nut fitting hole inside,
A wheel nut characterized in that a folded flange portion formed by folding outward from the opening end of the nut fitting portion is formed integrally with the nut fitting portion on the outer peripheral surface side of the nut fitting portion. wrench. The wheel nut wrench according to claim 1, wherein an outer peripheral surface of the nut fitting portion and an inner peripheral surface of the folded flange portion are in close contact with each other. The wheel nut wrench according to claim 1 or 2, wherein an inner diameter is gradually reduced from the nut fitting portion toward the handle portion side. The nut fitting portion is provided on one end side of the handle portion via a bent portion formed by bending the steel pipe,
The bent portion is provided with a plurality of ribs extending along the length direction of the bent portion and projecting radially outward from the outer peripheral surface at a predetermined interval in the circumferential direction. The wheel nut wrench according to any one of claims 1 to 3, wherein the wheel nut wrench is characterized.

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