JPH10211540A - Manufacture of hexagonal headed bolt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hexagonal headed bolt by forming a bolt blank composed of a hexagonal head part and a shaft part only with a heading- formation from a bar-like metallic material. SOLUTION: The bar-like metallic material A cut to a prescribed length is firstly punched to the die hole 2 of a die 1 with a first punch 5 to perform the end part of the metallic material A. Successively, a second punch 6 is advanced to intrude the tip part thereof into the die hole 2 of the die 1 and thereby, the end part of the metallic material A is pressed to the inner periphery of the die hole 2 and also, the bolt blank B composed of the hexagonal head part 11 and the shaft part 12, is formed by pressing and forming with the tip end surface 7 of the second punch 6. Thereafter, a screw groove is engraved on the peripheral surface of the shaft part 12 in the bolt blank B. The hexagonal headed bolt having the same shape as the head part of a trimming bolt is obtd. in a low cost.

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 hexagonal head bolt which is formed by forming a bolt material having a hexagonal head and a shaft portion by forging a rod-shaped metal material.

[0002]

2. Description of the Related Art Normally, as shown in FIG.
From the lower edge of 1 c to the bottom of the head 21, it is desirable that the corner 21 a where the side surfaces contact each other is formed in an angular shape, and the top surface 21 b of the head 21 is formed in a perfect circular shape. When the head 21 is formed in this manner, when the bolt is fastened with a wrench, particularly a power wrench, the center of the wrench can be accurately aligned with the head 21.
Since the engagement of the wrench is also ensured, damage to the bolt head due to idle rotation of the wrench and the like can be prevented, and the fastening operation can be performed quickly. 22 is a shaft part of the bolt, 23
Indicates a thread groove engraved on the shaft.

Conventionally, for small bolts, for example, hexagonal head bolts having a screw diameter of 8 mm or less, a rod-shaped metal material is forged by a two-stage forging machine to form a bolt material comprising a head and a shaft. It is manufactured by forming. The manufacturing process will be described with reference to FIG. 5. As a two-stage press forming machine, although not shown, a die provided with a first punch and a second punch alternately moving forward and backward with respect to the front surface of the die. Is used, and a bar-shaped metal material is cut into a predetermined length by a cutting mechanism provided in the forging machine, and the cut metal material is cut (FIG. 1A).
First, the end of the metal material is preformed by being driven into a die by the first punch (b in the same figure), and then pressed by the second punch to forge the end of the metal material into a short cylindrical shape. To form a bolt material consisting of a round head and a shaft (FIG. 3c). After that, the head of this bolt material is punched out into a hexagonal shape by a trimmer in another process to form a hexagonal head bolt material (d in the same figure). A screw groove is engraved (e in the figure).
In addition, a in FIG. 6D shows a scrap when a round head portion of a bolt material is punched into a hexagon.

The hexagonal head bolt manufactured in this manner is called a trimming bolt, and its head is formed as shown in FIG. 6, so that a high quality bolt can be obtained.

[0005] However, in the case of this trimming bolt, it is necessary to further perform a trimming process on the bolt material formed by forging, so that it takes much time and a scrap is generated. Will happen. In addition, when the head is punched into a hexagon, defective products such as deformation of the head are generated, and extra work is required for sorting. Therefore, although the trimming bolt is of high quality, it has a disadvantage of being expensive. Moreover,
Since burrs are generated on the periphery of the bottom surface of the bolt head by the trimming process, when fastening the bolt, the burrs may damage the surface of the workpiece. Also, in the case of trimming, the shaft of the bolt material is required to be longer than a predetermined length due to the structure of the machine, and for those with dimensions smaller than that, depending on the material, trimming is difficult or impossible, On the other hand, if the length is longer than a predetermined length, it must be processed using a machine one rank higher, so that the dimensions of bolts that can be manufactured are limited.

[0006] Conventionally, small bolts are manufactured by the following method in addition to the above. That is, as shown in FIG. 7, a bar-shaped metal material 40A cut into a predetermined length is cut into a first punch 35 by using a two-stage forging machine having a hexagonal mold hole 32 on the front surface of a die 31.
By punching into the mold hole 32 of the die 31, the end of the metal material 30A is preformed (a in the figure), and then the second punch 36 is advanced to a position immediately near the front surface of the die 31, and the tip of the punch 36 Pressing the end of the metal material 40A on the surface,
A bolt material 40B composed of a hexagonal head portion 41 and a shaft portion 42 is formed by forming the die material hole 32 into the shape of the die hole 32 (b in the drawing). This is a method of engraving a groove.

[0007] The hexagonal head bolt manufactured by this method is called an upset bolt. In the case of an upset bolt, the head is simply pressed with a punch to form a hexagon which is the shape of a die hole 32 of a die. Since it is only molded, the molding of the head is not always sufficient, so that as shown in FIG. 8, the side surface of the head 41 not only does not have a corner 41a having an angular shape but also has a top inclined surface 41c. The corner 41a connected to the head is drooped, and the top surface 41b of the head is
Was formed not in a perfect circle but only in a slightly deformed state. Therefore, the quality was considerably inferior to the trimming bolt.

However, since the upset bolt does not require trimming at the time of manufacture, it can be manufactured at a low cost, and since there is no burrs on the bolt head, there is no danger of damaging the surface of the workpiece. Because it is excellent and can be manufactured without restriction on the length of the shaft of the bolt material, it has the advantage of providing various types of bolts, and therefore, where high quality is not required, it is still used today. I have.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to make it possible to obtain a head having the same shape as the head of a conventional trimming bolt without performing a trimming process. An object of the present invention is to provide a method of manufacturing a hexagonal head bolt which is manufactured by forming a bolt material having a hexagonal head and a shaft portion only from a bar-shaped metal material by only forging.

[0010]

That is, in order to achieve the above object, the present invention alternately moves a die 1 having a hexagonal mold hole 2 formed in the front thereof and a die 1 having a concave front surface. A rod-shaped metal material A having a first punch 5 and a second punch 6 and cut into a predetermined length is first driven into the mold hole 2 of the die 1 by the first punch 5 to form a metal material A.
Is preformed and then pressed by the second punch 6 to form the end of the metal material A into the shape of the die hole 2 of the die 1, thereby forming the hexagonal head 11. In a method of manufacturing a hexagonal head bolt in which a bolt material B including a shaft portion 12 is formed and a thread groove 13 is engraved on a peripheral surface of the shaft portion 12 of the bolt material B, a die hole of the die 1 is formed. 2 is formed at a depth slightly larger than the height of the head 11 of the bolt material B, and the tip of the second punch 6 has a hexagonal shape whose outer periphery is the same as the inner periphery of the die hole 2 of the die 1. When the second punch 6 is pressed, the tip of the metal material A is pressed into the inner periphery of the mold hole 2 by pressing the tip of the second material into the mold hole 2 of the die 1. By pressing and molding at the tip end surface 7 of the two punches 6,
A bolt material B including a hexagonal head 11 and a shaft 12 is formed.

[0011]

[Operation] Since the manufacturing process is performed as described above, when the second punch 6 presses, the tip of the die enters the die hole 2 of the die 1 so that the inside of the die hole 2 is sealed. The end of the material A is pressed against the inner periphery of the mold hole 2 and pressed by the end face 7 of the tip end of the second punch 6 to be formed. The head 11 of the bolt material B manufactured for that purpose
From the lower edge of the top inclined surface 11c to the bottom surface of the head 11, the corner 11a of the side surface is formed in an angular shape, and the top surface 11b of the head is formed in a perfect circular shape. . Therefore, the thread groove 1 is formed in the shaft portion 12 of the bolt material B.
By engraving 3, a bolt similar to the trimming bolt can be obtained. And the head 11 of the bolt material B is
Since the head 11 is formed only by forging from a metal material,
Not only is there no risk of occurrence of burrs on the bottom surface of the bolt material, but also it can be manufactured without being restricted by the length of the shaft portion 12 of the bolt material B at the time of molding, so that various types of bolts can be provided.

In the practice of the present invention, the second
The tip end face 7 of the punch 6 is made of a bolt material B to be forged.
Of the head 11, ie, the top surface 11b and the top inclined surface 1
Needless to say, it is formed into a mold corresponding to 1c.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a die provided in a two-stage forging machine used in carrying out the present invention, and a bolt material B to be forged in the center of the front surface thereof.
The hexagonal mold hole 2 is recessed at a depth slightly larger than the height of the head 11 of FIG. Reference numeral 3 denotes a slot-shaped mold hole which is formed concentrically with the mold hole 2 and communicates with the bottom surface of the mold hole 2.
The diameter is formed to be the same as the diameter of a rod-shaped metal material A described later. Reference numeral 4 denotes a knockout pin fitted to the rear of the mold hole 3. Reference numeral 5 denotes a first punch provided in the head forming machine;
Is a second punch, which is provided so as to alternately advance and retreat with respect to the front surface of the die 1. And this second punch 6
As shown in FIG. 2 and FIG.
Is formed in a hexagon having the same shape as the inner periphery of the mold hole 2, and the tip end surface 7 is formed in a concave shape with a circular portion 7a substantially inscribed in the hexagon of the outer periphery, and this circular bottom portion 7a is formed of a bolt material. B is formed as a molding surface of the top surface 11b, and a portion 7b extending from the periphery of the circular bottom portion 7a to the outer periphery of the tip end surface 7 is formed in an oblique manner.
Is formed as a molding surface of the top inclined surface 11 c of the head 11.

Next, a process of forging a rod-shaped metal material by the above forging machine to manufacture a bolt will be described with reference to FIGS. The rod-shaped metal material is cut into a predetermined length by a cutting mechanism equipped in the head forming machine, and the cut metal material A is first advanced by the first punch 5,
The end face of the bar-shaped material A is preformed by driving the die 1 into the mold hole 2 of the die 1 (FIG. 1a), and then the first punch 5 is retracted. After that, the second punch 6 is advanced to make its tip end enter the die hole 2 of the die 1, and press the end of the metal material A against the inner periphery of the die hole 2,
Pressing is performed at the tip end surface 7 of the punch 6 (FIG. 1).
b). In this case, the inside of the die hole 2 is sealed at the tip of the second punch 6, and in this state, the end of the metal material A is pressed and molded, and the hexagonal head 11 and the shaft 12 are formed. Is formed (FIG. 2). By being molded in this manner, the head 11
Both the side surface and the top are formed sufficiently, so that the head 11 is formed in a shape in which the side corners 11a are angular from the lower edge of the top inclined surface 11c to the bottom of the head 11. The top surface 11b is formed in a perfect circular shape at the circular bottom surface 7a of the end face 7 of the tip end of the second punch. Thereafter, the second punch 6 is retracted, and the knockout pin 4
To discharge the bolt material B out of the die 1.
By repeating the above operation, the bolt material B is replaced with the metal material A.
Is manufactured continuously.

Then, the bolt material B is sent to a thread rolling machine, and a thread groove 13 is formed on the peripheral surface of the shaft portion 12 of the bolt material B by the thread rolling machine. Thus, a hexagonal head bolt as shown in FIG. 4 can be obtained.

Incidentally, in the case of the bolt material B which is forged and formed as described above, as shown in FIG. 2, the lower end 11d of the corner 11a on the side surface of the head 11 is formed in a round shape. This is because scum such as metal powder generated by shaving the metal material A at the time of the head forming is deposited on the corner of the bottom surface of the die hole 2 of the die 1. An air vent hole is provided at the corner of the bottom surface of 2 to prevent deposition, and also in the case of the above embodiment, by adopting a similar structure, it is possible to prevent the lower end portion 11d from having a rounded shape. Can be prevented to some extent.

The present invention is carried out as described above. In this case, the circular bottom 7a of the end face 7 of the tip of the second punch 6 is used.
The diameter and the inclination angle of the peripheral inclined portion 7b may be adjusted individually according to the size of the bolt to be manufactured, that is, the size of the bolt material B to be forged. For example, in the standard, as shown in FIG. 6, the top surface 21 b of the head 21 of the bolt needs to be formed in a circular shape having a size substantially inscribed in the hexagon of the head 21. It is preferable to set the size of the circular bottom portion 7a of the end face 7 of the tip end of the second punch so as to be slightly smaller than the standard (FIG. 3). Further, according to the standard, the angle of the top inclined surface 21c is set to be 30 degrees with respect to the top surface 21b. However, in the case of practicing the present invention, the peripheral slope is set so as to be somewhat gentler than the standard. It is preferable to set the angle of the shape 7b. Even if it carries out in this way, there is no problem in the quality of the bolt. And by carrying out in this way, the front end face 7 of the second punch 6 is formed during the forging.
There is an effect that it is possible to reduce an accident that the peripheral inclined portion 7c is chipped.

In practicing the present invention, the degree to which the tip of the second punch 6 enters the die die hole 2 during the pressing of the second punch 6 depends on the size of the bolt material B to be forged. It is necessary to adjust the stroke of No. 6 so as to prevent the head 11 from being insufficiently formed.

In practicing the present invention, the second punch 6 is formed by projecting a cross at the center of the circular bottom surface 7a of the end face 7 of the tip end, thereby providing the top surface 11a of the head.
A bolt having a cross groove can be manufactured.

In manufacturing a bolt by the method of the present invention, when a bolt is manufactured by incorporating a washer into a base portion of a shaft portion of a bolt material by a conventional method during a manufacturing process,
It goes without saying that a washer-incorporated bolt can be obtained.

[0021]

As described above, according to the method of the present invention, at the time of pressing by the second punch, the end of the rod-shaped metal material is caused to enter the die hole of the die by pressing the end thereof into the die hole. Pressing the inner periphery of the hole and pressing at the end face of the tip of the second punch to form a bolt material consisting of a hexagonal head and a shaft, and manufacturing the bolt material, From the lower edge of the top inclined surface to the bottom surface of the head, the head is formed in a shape in which the side corners are angular, and the top surface is formed in a perfect circular shape, and the conventional head is formed. A hexagonal head bolt having the same shape as the head of the trimming bolt can be manufactured.

According to the method of the present invention, the die hole of the die is formed at a depth slightly larger than the height of the head of the bolt material, and the tip end of the second punch has the outer periphery formed by the die mold. It is formed into a hexagon having the same shape as the inner circumference of the hole, and when pressing by the second punch, the tip is inserted into the die hole of the die. A bolt can be manufactured by forming a bolt material only by slightly improving the structure of the mold hole and the degree of advance of the second punch at the time of pressing. Therefore, it can be easily implemented, and it is possible to provide a high-quality bolt at low cost, in combination with the fact that trimming is unnecessary.

Further, according to the method of the present invention, the head of the bolt material is formed only by forging from a metal material, so that there is no danger of burrs on the bottom surface of the head unlike a trimming bolt. Because it can be manufactured without restriction on the length of the shaft of the bolt material at the time of molding,
There is an effect that various types of bolts can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a manufacturing process when embodying the present invention.

FIG. 2 is an enlarged vertical sectional view of a main part of a second punch in FIG. 1 and a bolt material pressed and formed by the second punch.

FIG. 3 is a front view of a second punch in FIG. 2;

FIG. 4 is a perspective view of a hexagonal head bolt manufactured by the method of the present invention.

FIG. 5 shows a process of manufacturing a conventional trimming bolt until a bolt is manufactured from a rod-shaped metal material;
The upper part is a plan view, and the lower part is a side view.

FIG. 6 is a perspective view of a hexagonal head bolt manufactured by the method of FIG. 5;

FIG. 7 is a cross-sectional view showing a part of a manufacturing process of a conventional upset bolt.

FIG. 8 is a perspective view of a hexagonal head bolt manufactured by the method of FIG. 7;

[Explanation of symbols]

 Reference Signs List 1 die 2 hexagonal mold hole 5 first punch 6 second punch 7 tip end face of second punch 7a circular bottom face at tip end face of second punch 7b peripheral bevel at tip end face of second punch A Rod-shaped metal material B Bolt material 11 Head of bolt material 11a Hexagonal corner of head 11b Top surface of head 11c Top inclined surface of head 12 Shaft of bolt material 13 Screw groove

Claims (1)

[Claims] 1. A die 1 having a hexagonal mold hole 2 formed in a front surface thereof, a first punch 5 and a second punch 6 alternately moving forward and backward with respect to the front surface of the die 1, and having a predetermined length. The bar-shaped metal material A cut into pieces is first driven into the mold hole 2 of the die 1 by the first punch 5 to preform the end of the metal material A, and then pressed by the second punch 6. ,
The end of the metal material A is formed into the shape of the die hole 2 of the die 1 so that the hexagonal head 11 and the shaft 1 are formed.
In the method of manufacturing a hexagonal head bolt formed by forming a bolt material B made of No. 2 and thereafter engraving a thread groove 13 on the peripheral surface of the shaft portion 12 of the bolt material B, the die hole 2 of the die 1 And the tip of the second punch 6 is formed in a hexagonal shape having the same outer periphery as the inner periphery of the die hole 2 of the die 1 while being formed at a depth slightly larger than the height of the head 11 of the bolt material B. Then, at the time of pressing by the second punch 6, the tip of the metal material A is pressed into the inner periphery of the mold hole 2 by causing the tip of the second punch 6 to enter the mold hole 2 of the die 1. 6
Forming a bolt material B comprising a hexagonal head portion 11 and a shaft portion 12 by pressing and shaping the tip end surface 7.