JPS61180638A - Split pin hole making method of bolts - Google Patents

Abstract

PURPOSE:To simplify the split pin hole making of bolts by punching split pin hole with driving a punch onto the following hollow after forming the shallow hollow having about the same diameter as the split pin hole at the prescribed position with constraining the bolt before threading. CONSTITUTION:The shallow hollows 18a, 18b having about the same or slightly larger diameter as the necessary split pin hole are formed by punches 16a, 16b with constraining by constraining jig 10 the thread lower diameter part 13 which is before threading of bolt 12 at the first stage. At the second stage the bolt 12 forming the hollows 18a, 18b is pressed to the constraining jig 20, punching punch 24 is driven onto the hollows 18a, 18b and the split pin hole 25 is subjecting to punching. The split pin hole making of bolts can be thus performed with the punching by punch.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a bolt for manufacturing a cotter pin hole for fitting a cotter pin for preventing rotation of a nut into a threaded portion of a bolt used in a mechanical part of an automobile, etc. This article relates to methods for machining cotter pin holes.

(Prior art) The conventional method for drilling split pin holes in bolts is as follows:
For example, there is something like the one shown in FIG.

Figure 7 shows a pole stud used in a pole joint for an automobile.As shown in enlarged view as part A, the lower diameter portion 2 of the thread of the pole stud shaft 1 before being threaded is drilled. The split pin hole 3 is drilled and finished by chamfering both sides of the drilled hole.

Further, instead of drilling holes using a drill, punching the split pin holes using a punch has also been proposed.

(Problems to be solved by the invention) However, in machining, drilling with such a conventional drill takes time because it is a cutting process, and the drilling process requires two chamfering processes later. There was a problem in that the number of man-hours required for processing increased.

In addition, when punching with a punch, the machining distance fV can be shortened, but since it is punching into a curved surface, if the bolt axis is not aligned accurately so that the punch axis passes through, the screw When the punch is driven into the first diameter portion, the bolt side moves and bending stress is applied to the punch, which causes the punch to easily break, resulting in a short life span and a lack of economic efficiency.

(Means for Solving the Problems) The present invention has been made in view of these conventional problems, and aims to shorten the processing time by using a punching process, and also to reduce the occurrence of bending stress during punching. To provide a method for machining split pin holes for bolts, which prevents the damage and ensures the durability of a punch.

In order to achieve this object, the present invention provides a bolt threading method in which a split pin hole is formed in a direction perpendicular to the axis of a bolt used in a mechanical part of an automobile, etc. The first step is to form a shallow recess with approximately the same diameter or slightly larger diameter than the split pin hole on both opposite sides of the pin hole machining position or on one side that will be the punch driving side while restraining the 1 diameter portion of the previous screw. This method includes a second step of punching a split pin hole by driving a punch into the recess formed in the first step.

(Example) Fig. 1 is a cross-sectional explanatory diagram showing the first step in the split pin hole machining method of the present invention.
As shown in the figure.

In the first step shown in FIG. 1.2, the screw 1 diameter portion 13 at the tip of the bolt 12 to be processed is fitted into the bolt set hole 11 formed in the restraining jig 10, and the processing position is determined. The outer circumferential portion of the screw 1 diameter portion 13 is held down by the restraining jig 10, and with the screw 1 diameter portion 13 fixed by the illustrated restraining jig 10, the upper and lower portions of the screw 1 diameter portion 13 are Through holes 14.15 are provided in the holes 14.15, and in the first step, the punches 16a, 16b are pressed against the lower diameter portion 13 of the screw 1 from above and below through the through holes 14.15, and the tips of the punches 16a, 16b are pressed. A shallow recess 18a is formed by causing plastic deformation that causes the portion to bite into the screw 1 diameter portion 13.

18b are formed at opposite positions. This punch 15a,
In forming the recesses 18a and 18b by pressurizing the punches 16b, since the outer peripheral portion of the screw 1 diameter portion 13 is restrained by the restraining jig 10, the flow of material due to deformation when pressurizing with the punches 16a and 16b is in the axial direction. This occurs only in the process of rolling, and does not deform the screw 1 diameter portion 13, which has been created to a specified size by rolling or the like.

In addition, the sizes of the depressions 18a and 18b formed in the diameter portion 13 of the screw 1 by pressurizing the punch in the first step are as follows:
A recess is formed with the same or slightly larger diameter than the split pin hole.

Furthermore, the shape of the depressions 18a and 18b is similar to that of the punch 15.
It is determined depending on the shape of the tips of a and 16b. In this embodiment, since the tip of the punch is spherical, spherical depressions 18a and 18b are formed in the outer peripheral portions on opposite sides of the screw 1 diameter portion 13 in the first step.

FIG. 3 is a cross-sectional explanatory diagram showing the second step of punching a split pin hole by driving a punch into the first diameter portion of the screw where a recess was formed in the first step shown in FIG. 1.2; FIG. 4 shows the IV-IV cross section.

In the second step shown in FIGS. 3 and 4, the depressions 18a, 1
8b is inserted into the bolt set hole 21 of the restraint jig 20, and presses down the outer circumference of the screw 1 diameter portion 13, which will be the processed part, and when assembled into the bolt set hole 11, the bolt 12 is inserted into the bolt set hole 21 of the restraining jig 20. Bunch guide hole 22 on the 18a side
is formed, and a scrap removal hole 2 is formed on the recess 18b side.
3 is opened, and the inlet side of the scrap removal hole 23 is a depression 1.
The hole 23a has a small diameter corresponding to the diameter of the hole 8b, and when the bolt 12 is set to the restraint jig 20, the punch 24 is inserted through the punch guide hole 22 into the recess 18a.
from the depression 18a to the depression 1 as shown in the figure.
The split pin hole 25 is punched out by punching the screw 1 diameter portion 13 toward the direction 8b. The scrap 26 produced by punching the split pin hole 25 with the punch 24 is discharged to the outside from the lower scrap removal hole 23.

In punching the split pin hole using the punch 24, the recess 18a is pre-formed in the first step on the outer peripheral surface of the screw 1 diameter portion 13 into which the punch 24 is driven. punch 24
However, it is received in a recess 18a having the same or slightly larger diameter than the punch 24, and by stabilizing the tip of the punch, it is possible to reliably prevent punch bending that occurs during punching. Furthermore, in the first step, a recess 18 that is the same as or slightly larger than the punch 24 is formed in the screw 1 diameter portion 13 on the punching side of the punch 24.
Since the depression 18b is formed, the deformation of the material caused by the punching is absorbed, and it is possible to prevent the occurrence of pars on the punching side.

Fig. 5.6 shows another shape of the recess formed in the first step shown in Fig. 1.2. Fig. 5 shows that the tip of the punch is shaped like a truncated cone so that the hole can be screwed in the first step. 1 diameter portion 13
Trapezoid-shaped depressions 26a and 26b are formed on opposite sides of the screw 1, and in FIG. depressions 27a and 27b are formed.

When the trapezoidal or conical depression shown in Fig. 5.6 is formed in the first step, the second step shown in Fig. 3.4 is formed.
The punch used for punching split pin holes in the process has a shape opposite to the depression formed in the first process. For example, in FIG. 5, a punch with a truncated conical tip is used. In the case of FIG. 6, it is preferred to use a punch with a conical tip.

FIG. 7 shows a more specific example of the first step of the split pin hole machining method of the present invention for automobile pole studs, in which the pole stud 30 is housed in a socket via a bearing. It has a pole part 30a and a shaft part 30b formed integrally with the ball part 30a, and the tip of the shaft part 30b becomes a screw 1 diameter part 13, and a split pin hole is machined in this screw 1 diameter part 13. Therefore, as the bolt set hole 11 of the restraint jig 10 used in the first step, the diameter portion 13 of the screw 1 in which the split pin hole is machined is restrained and fixed with a hole shape that matches the shaft portion 30b of the pole stud 30.
Punches 16a and 16blD for forming a recess are applied from both sides of the diameter portion 13 of the screw 1. this punch 1
When applying pressure to form a depression by 6a and 16b,
Since the outer periphery of the diameter portion of the screw 1 is tightened by the restraint jig 10, the direction of the tip of the shaft portion and the ball portion 3Qa
A sideward flow of material occurs, causing axial deformation on both sides. However, since the length from the center of the ball part 30a to the split pin hole processing position must be a specified dimension, the axial restraint jig 32 is brought into contact with the tip of the ball part 30a in the axial direction, and the punches 16a, 16b are When a recess is formed, the axial deformation occurs only in the direction of the tip of the shaft portion 30b, and even if the recess is formed by pressure from the punches 16a and 16b, the distance from the center of the ball portion 30a to the center of the split pin hole is I try not to change the dimensions.

The use of such an axial restraint jig 32 is also used in the second step in which a punch is driven into the recess formed in the first step, so that even if axial deformation occurs during the punching process, The specified dimensional relationships required for the pole stud 30 are not affected.

In the above embodiment, the depressions were formed on both the driving side and the punching side in the first step, but the depressions may be formed only on the driving side.

(Effects of the Invention) As explained above, according to the present invention, in the first step, while restraining the first diameter portion of the screw before machining the threaded hole of the bolt, a shallow recess with a diameter approximately the same as or slightly larger than the split pin hole is formed. are formed on opposite sides of the cotter pin hole machining position or on one side that will be the punch driving side, and in the next second step, a punch is driven into the recessed part formed in the first step to punch and process the cotter pin hole. As a result, in the pre-punching process, a depression is pre-formed in the processing area where the punch will be driven, and a punch with the same or slightly narrower diameter as the diameter of this depression is driven, ensuring the stability of the punch tip during driving. is,
It reliably prevents the punch from bending due to driving, guarantees the durability of the punch used for punching, and also allows the split pin hole to be drilled approximately at right angles to the shaft, and the size of the recess formed in the first step is also improved. If the depth and depth are determined appropriately, it is possible to achieve the same machined shape as chamfering both sides of a split pin hole using chamfering.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the first step in the processing method of the present invention, FIG. 2 is a cross-sectional view taken along If-IF in FIG. 1, and FIG. 3 is a cross-sectional view showing the second step in the processing method of the present invention. Figure, 4th
The figure is a cross-sectional view taken along the line IV-rV in Figure 3, Figure 5.6 is an explanatory diagram showing the types of recesses formed in the first step, and Figure 7 is a specific example of machining a cotter pin hole in an automobile ball stud. FIG. 8 is an explanatory cross-sectional view showing the first step, and FIG. 8 is an explanatory view showing the conventional method. 10.20: Restraint jig 11.21: Bolt set hole 12: Bolt 13: Thread lower diameter portion 14.15: Through hole 16a, 16b: Punch 18a, 18b: Recess 23 Varnish scrap removal hole 24: Punch punch 25: Cotter pin Hole 26: Scrap 30: Ball stud 30a: Ball portion 30b = Shaft portion 32: Axial restraint jig

Claims (1)

[Scope of Claims] In a method for forming split pin holes for bolts used in mechanical parts of automobiles and the like from a direction perpendicular to the shaft, the lower thread diameter of the bolt before thread processing is provided. A first step in which a shallow recess with a diameter approximately the same as or slightly larger than the split pin hole is formed on opposite sides of the split pin hole machining position or on one side that will be the punch driving side while restraining the portion; and forming in the first step. A method for machining cotter pin holes for bolts, comprising a second step of punching a cotter pin hole by driving a punch into the recessed part.