JPS5916537B2 - How to form a countersunk hole with a locking mechanism - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for forming several holes for locking.

Since the countersunk hole into which the countersunk head of the mounting screw fits generally has a simple conical surface, it does not have a sufficient locking function as it is.

In particular, if the allowable dimensional difference is relatively large, for example, if the countersunk head of a countersunk head screw and the threaded part are eccentric, or if the countersunk hole and the screw hole are eccentric, the countersunk head and countersunk hole will Since each conical surface only partially contacts each other, resulting in so-called uneven contact, it is in a state where it is extremely easy to loosen.

Therefore, caulking or other measures must be taken to prevent loosening.

The present invention was made based on the above-mentioned circumstances, and
The purpose is to provide a method for forming a number of locking holes that can reliably prevent loosening even if there are slight dimensional errors in each part.

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIG. 1, the mounted member a is, for example, a striker for a door lock device, and includes a base plate 1 and an inverted U-shaped leg 2 erected on the base plate 1. It is configured to be attached to the main body by means of a countersunk head screw 6 which passes through a countersunk hole 3 and is screwed into a screw hole 5 in the main body.

The conical surface 3a of the countersunk hole 3 has a plurality of protrusions 7...
・Protrudingly installed.

The projections 7 are arranged at intervals in the circumferential direction and have a radial shape, and as shown in an enlarged view in FIG. 1C, the tightening direction of the countersunk head screw 6 is clockwise in FIG. If so, it is formed by cutting and raising in the opposite direction.

The countersunk hole 3 having the protrusions 7 has a first step of forming a conical surface 3a, and a second step of forming the protrusions 7 on the conical surface 3a.

The first step may be equivalent to normal countersinking, for example by turning or pressing, or by any other means.

In the second step, the attached member a on which the conical surface 3a was formed in the first step is attached to the lower mold 10 as shown in FIG. 2A.

An upper mold 11 that faces the lower mold 10 and is movable up and down includes a main body 12 and a lid 13.

The main body 12 is formed with a vertical screw hole 14 that is concentric with the conical surface 3a, and a recess 15 that is connected to the screw hole 14 and is approximately L-shaped. A through hole 16 concentric with the hole 14 is formed.

The punch 17 has a threaded portion 18 that threads into the threaded hole 14;
Arm portion 19 located within the recess 15 and extending in the radial direction
The spring member 20 provided in the recess 15 urges the counterclockwise direction (FIG. 2B) via the arm 19, and the contact between the arm 19 and the side wall of the recess 15 causes the clock to move in the same direction. Rotation in the direction is prevented.

The punch 17 has a conical surface 2 at its lower end that protrudes through the through hole 16 and has an apex angle substantially equal to the conical surface 3a.
1 and is provided with a plurality of blades 22 protruding from this conical surface 21.

The blades 22 are arranged at intervals in the circumferential direction and have a radial shape, and have a serrated cross section as shown in an enlarged view in FIG. When the lower mold 10 and the upper mold 11 are brought close to each other using a press device (not shown), the respective cutting edges of the blades 22 of the punch 17 first collide with the conical surface 3a of the attached member a.

When both dies io and 1i are brought closer together from this state, the blades 22... bite into the conical surface 3a, and the punch 1
7 receives an axial thrust, and the screw portion 18 is rotated clockwise in FIG. 2B against the screw hole 14 against the spring member 20. As shown in FIG.

That is, as the punch 17 is rotated and pressed against the conical surface 3a, the blades 22... bite into the conical surface 3a and cut it up to form the projections 7... as shown in FIG.
is formed, and the second step is completed.

After the second step is completed as described above, the lower mold 10
When the upper molds 11 are separated from each other, the punch 17 automatically returns to the initial position shown in the figure by the biasing force of the spring member 20.

Further, the attached member a is removed from the lower mold 10 and subjected to appropriate heat treatment, etc., as necessary.

Note that 23 and 24 in the figure are gaps for allowing relative axial displacement between the punch 17 and the upper mold 11.

In the countersink hole 3 formed through the first and second steps, the protrusions 7 protruding from the conical surface 3a are cut in a direction opposite to the tightening direction of the countersunk screw 6. Since the countersunk head screw 6 is formed by the Since it generates a large resistance force against, it does not cause loosening.

In addition, even if the dimensional tolerance is relatively large, the protrusion 7...
Since the occurrence of uneven contact can be effectively prevented by the deformation of , it is possible to prevent loosening in the same manner as described above.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that various changes and applications can be made within the scope of the gist thereof.

For example, instead of being rotated by thrust, the punch 17 may generate thrust by being rotated.

Furthermore, the projections 7 may be arranged at intervals not only in the circumferential direction but also in the radial direction.

The present invention comprises a first step of forming a conical hole as described above, and a second step of forming a protrusion in the conical part of the hole, and the protrusion is fitted into the conical hole. Since the cut is made in the opposite direction to the tightening direction of the countersunk screw to be inserted, in the tightened state, the protrusion is strongly pressed against the opposing conical surface of the countersunk screw, creating a large resistance force in the loosening direction. It is possible to form several locking holes that can reliably prevent loosening even when the conical surfaces of the screw and countersunk hole are eccentric or inclined relative to each other.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1A is a front view, FIGS. B and C are sectional views taken along lines B-B and C-C in FIG. Longitudinal sectional view; Figure B is a cross-sectional view taken along line B-B in Figure A; Figure 3A is a view taken along the ■-■ arrow in Figure 2A; Figure 3B is a cross-sectional view taken along line B-B in Figure A; It is a sectional view along a line. 3... countersunk hole, 3a... conical surface, 5...
...Screw hole, 6...Countersunk head screw, 7...
...Protrusion, 10...Lower die, 11...Upper die, 14...Screw hole, 17...Punch, 18... Threaded part, 21...conical surface,
22...Blade.

Claims (1)

[Claims] 1. A first step of forming a conical hole into which the countersunk head of the mounting screw can fit, and a punch with a plurality of blades protruding at intervals from the tip facing the conical hole. A method for forming a multiple locking hole, comprising a second step of cutting and raising a locking protrusion by pressing against the conical portion of the hole while rotating in a direction opposite to the tightening direction.