JP2000218341A - Bolt manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bolt manufacturing method wherein a head part processing efficiency is good, a head part superior in strength is obtainable while a material loss is not generated, by molding a head part to be installed at one end side of a drum part under a cold draw processing. SOLUTION: In this method, a tip end drawing die on which a round draw hole is installed, and a head part drawing die on which a polygonal head molding hole and an inducing tapered hole are installed at its inserting end, are used. First, a small diameter part is draw processed by cold pressure insertion of a bolt material 12 end part into the drawing hole of the tip end drawing die. Then, a small diameter part of the bolt material 12 is cold pressure inserted into a molding hole of the head part drawing die so as to draw process an axial shape polygonal head part 15 on the end part of the bolt material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bolt, and more particularly, to a method for drawing an axial polygonal head at an end of the bolt.

[0002]

2. Description of the Related Art As a bolt used for various fastenings, there is a bolt provided with a polygonal head having a slightly smaller diameter than one end of a body formed with a male screw.

Conventionally, such a method of manufacturing a bolt cuts a bolt material of a predetermined length from a rod material or a coil material,
A polygonal shaft-shaped head is formed on one end side of the bolt material by cutting, and then a thread is formed on the outer peripheral surface of the body of the bolt material.

[0004] Such a bolt has an advantage that a tool such as a spanner can be engaged with a polygonal head provided on one end side of the body, so that screwing and fastening of the bolt can be performed smoothly.

[0005]

By the way, the method of forming the head provided at one end side of the body portion by cutting not only has a low processing efficiency but also cuts and removes the bolting surface (surface) of the bolt material. , While reducing the strength,
There is a problem that material loss due to cutting powder occurs.

Accordingly, an object of the present invention is to form a head provided on one end side of a body by drawing.
It is an object of the present invention to provide a method of manufacturing a bolt which has good processing efficiency of the head, has excellent strength, and has no material loss.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, a first aspect of the present invention is to provide a head diaphragm having a polygonal head forming hole and a tapered portion for introduction at its insertion end. A configuration in which an end of a bolt material cut to a predetermined length is cold-pressed into a forming hole of the die using a die to draw an axial polygonal head at an end of the bolt material. Is adopted.

According to a second aspect of the present invention, there is provided a tip drawing die provided with a circular drawing hole and a tapered hole for introduction at its insertion end, a forming hole of a polygonal head, and a tapered hole for introduction at its insertion end. First, the end of the bolt material cut to a predetermined length is cold-pressed into the drawing hole of the tip drawing die using a head drawing die provided with a small diameter to the end of the bolt material. Part is drawn, and then the small diameter part of the bolt material is cold-pressed into the forming hole of the head drawing die to draw a shaft-shaped polygonal head at the end of the bolt material. The configuration is adopted.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 shows a tip drawing die 1 for drawing a small-diameter circular portion at an end of a bolt material. A circular drawing hole 2 having a diameter smaller than that of the bolt material, and an insertion end at the insertion end thereof. A conical introduction tapered hole 3 is provided.

FIGS. 6A and 6B show a head drawing die 4 for drawing a small-diameter portion formed on a bolt material into an axial polygonal head. The insertion end has a tapered hole 6 for introduction. In the case shown,
The shaping hole 5 has an example in which a square head is machined, and has a shape in which flat portions 7 for chamfering are provided at four corners of the square hole, and the tapered hole 6 has a conical shape.

The tip drawing die 1 and the head drawing die 4
Are formed using a cemented carbide material, and as illustrated in the case of the head drawing die 4 in FIG. It is designed to be detachably housed inside and attached to a cold heading machine.

FIG. 1 shows a bolt material 12 used for forming a bolt 11, which is formed in a straight circular axis shape having a predetermined diameter and length, and which is obtained by cutting a rod-shaped metal material for a bolt with a cutting machine, What cut | disconnected the coil material for bolts by the cold heading machine is used.

FIG. 2 shows a body 12a of the bolt material 12.
An intermediate bolt material obtained by drawing a small-diameter portion 13 at one end using a tip drawing die 1 is drawn. The small-diameter portion 13 is drawn by a drawing hole 2, and a transition portion from the small-diameter portion 13 to the body 12a is introduced. Formed in the tapered portion 14 by the tapered hole 3 for use.

FIG. 3 shows the bolt blank 12 in which the small diameter portion 13 is drawn to the head 15, and the head 15 is formed with the forming hole 5.
And a tapered portion 14 from the head 15
The transition part to the head 1 is formed by the tapered hole 6 for introduction.
5 are arc-shaped bulging portions 16, and the four corners of the head 15 are chamfered by the cross-sectional shape of the forming hole 5.
It has become.

FIG. 4 shows the completed bolt 11 and the head 1
An external thread 18 is formed on the body 12a of the bolt material 12 provided with the thread 5. The external thread 18 is formed by rolling.

Next, a method of manufacturing a bolt will be described.

A bolt material 12 is set in a forging machine to which the tip drawing die 1 is attached, and the bolt material 12 is moved in the axial direction so as to be cold from the tapered hole 3 of the tip drawing die 1 toward the drawing hole 2. The bolt material 12 is press-fitted, and a circular-shape small-diameter portion 13 is drawn on one end of the bolt material 12.

Thereafter, the bolt blank 12 from which the small diameter portion 13 has been drawn is set in a forging machine to which the head drawing die 4 is attached, and the bolt blank 12 is moved in the axial direction.
A small diameter portion 13 is drawn into a square head 15 by cold press-fitting from the tapered hole 6 of the head drawing die 4 toward the drawing hole 5.

If the male thread 18 is rolled on the body 12a of the bolt blank 12 whose head 15 has been drawn, FIG.
Is completed as shown in FIG.

In the illustrated embodiment, the head 15 is formed in a square angular axis, but it may be formed in a polygon such as a hexagon or an octagon. 13 is omitted, and one end of the bolt material 12 is directly pressed into the head drawing die 4 to form a square shaft-shaped head 15.
May be directly drawn.

[0022]

As described above, according to the present invention, a polygonal head forming hole and a head drawing die provided with a tapered hole for introduction at the insertion end thereof are cut to a predetermined length. The end of the bolt material is cold-pressed into the forming hole of the die to draw the polygonal head at the end of the bolt material, so that one end has a polygonal shaft shape. The production of bolts with a head can be formed by cold drawing, which is more efficient and mass-produced than when the head is formed by cutting.Moreover, the strength of the head is increased by plastic deformation. The strength can be increased to the same degree as the trunk.

Also, there is no generation of chips in the formation of the head,
Material loss does not occur, and commercial value can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a bolt material.

FIG. 2 is a perspective view of a bolt material having a small-diameter portion processed.

FIG. 3A is a perspective view of a bolt material having a processed head.
(B) is an enlarged perspective view of the head.

FIG. 4 is a front view of the completed bolt.

FIG. 5 is a longitudinal sectional view of a tip drawing die.

6A is a longitudinal sectional view of a head drawing die, and FIG. 6B is a plan view of the same.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tip drawing die 2 drawing hole 3 taper hole 4 head drawing die 5 forming hole 6 taper hole 11 bolt 12 bolt material 13 small diameter portion 14 taper portion 15 head 18 male screw

Claims (2)

[Claims] 1. Using a head drawing die having a polygonal head forming hole and a tapered hole for introduction at an insertion end thereof, forming an end of a bolt material cut to a predetermined length into the die. A bolt manufacturing method, characterized in that a shaft-shaped polygonal head is drawn into an end of a bolt material by cold press-fitting into a hole. 2. Using a tip drawing die provided with a circular drawing hole and a head drawing die provided with a polygonal head forming hole and a tapered hole for introduction at the insertion end thereof. The end of the bolt material cut into length is cold-pressed into the drawing hole of the tip drawing die to draw a small-diameter portion at the end of the bolt material. A method for producing a bolt, comprising: drawing a shaft-shaped polygonal head at an end of a bolt material by cold press-fitting into a forming hole of a head drawing die.