JPH08267172A - Flange bolt forming die - Google Patents

Abstract

(57) [Summary] [Purpose] A flange bolt forming die that has a longer life than the upper die, reduces the work hardening of the portion that is sheared by the upper die, and reduces the processing force applied to the cutting edge. provide. [Configuration] The lower die 1 and the clearance angle α of the cutting edge are approximately 0 °
It consists of the upper die 2 and the upper die. The lower die 1 has a central hole 3
A ring-shaped projection 5 having a relief angle β for molding the outer periphery of the lower portion of the flange portion is provided around The upper die 2 has a cutting edge 6 for forming a polygonal bolt head on the inner peripheral portion, and is an annular body having a flat lower surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for forming a flange bolt having a seat surface having a diameter larger than a diagonal distance below a polygonal portion.

[0002]

2. Description of the Related Art A conventional general flange bolt forming die has a lower die 21 and an upper die 22 as shown in FIG. This lower die 21 is provided with an annular flat surface 24 and an annular protrusion 25 around the center hole 23,
Further, the upper die 22 was provided with a cutting edge 26 for forming a polygonal bolt head on the inner peripheral portion and an obliquely upward slope 27 on the outer peripheral portion. Further, the clearance angle α of the cutting edge 26 with respect to the head of the bolt was set to about 3 °. And lower die 21
A relief angle β is formed on the outer peripheral portion of the annular projection 25 of, and the structure is such that the scraps of the flange portion formed between the corner portions of the slope 27 are sheared and removed in a later step. .

However, in such a conventional flange bolt forming die, the upper die 22 is made of high speed steel, but there is a problem that the average life is very short, about 10,000 times. Further, there is a problem that the surface roughness of the portion sheared by the upper die is large.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and can greatly extend the life of the upper die, and reduces the surface roughness of the portion sheared by the upper die. The purpose of the present invention is to provide a die for forming a flange bolt that can be manufactured.

[0005]

The flange bolt forming die of the present invention made to solve the above problems is
A lower die with an annular projection around the center hole that receives the outer circumference of the lower part of the flange, and a cutting edge for forming a polygonal bolt head on the inner circumference, and an annular upper die with a flat lower surface. It consists of and. In addition, it is preferable to form an escape angle β for forming scraps of the flange portion on the outer peripheral portion of the annular protrusion. Also, keep the surface roughness of the upper die within 0.3a and set the relief angle α of the cutting edge for forming the bolt head of the upper die to approximately 0.
It is preferable to set it as °.

[0006]

According to the present invention, the entire lower surface of the upper die has a flat shape, and the clearance angle α of the cutting edge is approximately 0 °.
Therefore, an unbalanced load does not act on the cutting edge, and the load on the die is relaxed. Further, by forming the clearance angle β of the outer peripheral portion of the annular projection forming the lower die, distortion occurs in the scraps sheared in the post process of the flange portion by the lower die and the upper die, It does not compress waste and reduces work hardening and processing power.

[0007]

The present invention will be described below in more detail with reference to the illustrated embodiments. In FIG. 1, 1 is a lower die and 2 is an upper die. The lower die 1 has a central hole 3 into which a blank is inserted, and an annular flat surface 4 around the central hole 3.
And an annular projection 5 for molding the outer periphery of the lower portion of the flange portion. On the outer peripheral surface of the annular projection 5, there is formed an escape angle β for releasing the scrap as shown.
In the embodiment, the clearance angle β is about 25 °.

The upper die 2 is made of a cemented carbide tool steel having a higher compressive strength than the conventional high speed steel, and has an annular bottom surface with a flat bottom surface. A cutting edge 6 for forming a polygonal bolt head is formed on the inner peripheral portion thereof.
The clearance angle α of the cutting edge 6 with respect to the bolt head is approximately 0 °, and is configured so that an unbalanced load is not applied to the cutting edge 6. In order to prevent seizure between the upper die 2 and the blank, the upper die 2 is subjected to a surface treatment with a surface roughness of 0.3a or less to alleviate the load on the die.

FIG. 2 is a view showing a usage state of the flange bolt forming die. The upper die 2 is attached to the lower end of a punch case 7 having a long stroke and a two-step sliding cylinder shape. A concave punch spacer 8 is fitted inside the punch case 7, and an intermediate spacer 11 having a punch pin 10 projecting downward at the center is slidable inside a concave hole 9 of the punch spacer 8. It is provided in.

A disk-shaped load receiving plate 12 is provided on the upper ends of the intermediate spacer 11 and the punch case 7, and a pin 13 is inserted through the center of the load receiving plate 12. The disc-shaped load receiving plate 12 is fitted in an outer case 14 into which the punch case 7 is fitted.

A wide oil groove 15 is formed on the outer periphery of the punch spacer 8.
An oil hole 16 communicating with the oil groove 15 is formed below the oil groove 15 toward the lower head of the blank as shown in FIGS. Further, as shown in FIG. 2, the outer case 14 and the punch case 7 are provided with an oil inflow port 17 communicating with the oil groove 15 so that the processing oil can be supplied to the oil groove 15. . Separately from this, the processing oil is also supplied from the X direction in FIG.

In order to form a flange bolt with the flange bolt forming die thus constructed, a blank is set in the center hole 3 of the lower die 1, and the upper die 2 is set together with the outer case 14 and the punch case 7. Lower and press-mold the head of the flange bolt. At this time, the cutting edge 6 of the upper die 2 forms a polygonal bolt head, and at the same time, a flange scrap is formed between the annular projection 5 of the lower die 1 and the flat lower surface of the upper die 2. To do. At this time, the processing oil is supplied to the head portion and the flange portion of the blank as described above. The scraps are removed by shearing in a later process.

After the flange bolt is formed in this way, when the upper die 2 is raised together with the punch case 7, the flange bolt is also raised. Here, the pin 13 is lowered, the punch pin 10 of the intermediate spacer 11 collides with the head of the flange bolt, and the molded flange bolt is discharged downward.

[0014]

As described above, in the flange bolt forming die of the present invention, the entire lower surface of the upper die is flat and the relief angle α of the cutting edge forming the bolt head is approximately 0 °. Therefore, the unbalanced load does not act on the upper die, and the number of lives of the upper die can be significantly increased from the conventional 10,000 times to 240,000 times in the case of the embodiment. The surface roughness can be reduced to about 1/4 of the conventional level. Also, scraps of the flange are formed between the flat lower surface of the upper die and the annular projection of the lower die,
The scraps are distorted due to the clearance angle β of the outer peripheral portion of the annular projection, and the scraps are not compressed, so that the work hardening of the sheared surface can be reduced and the working force can be reduced. Therefore, the present invention is highly valuable as a flange bolt forming die that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a usage state.

FIG. 3 is a plan view showing an oil groove.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Lower die 2 Upper die 3 Center hole 4 Flat surface 5 Annular protrusion 6 Cutting edge 7 Punch case 8 Punch spacer 9 Punch hole 10 Punch pin 11 Intermediate spacer 12 Load receiving plate 13 Pin 14 Outer case 15 Oil groove 16 Oil hole 17 port

Claims (3)

[Claims] 1. A lower die having an annular projection for receiving a lower outer circumference of a flange portion around a center hole, and a cutting edge for molding a polygonal bolt head at an inner circumferential portion, and the entire lower surface is flat. A flange bolt forming die comprising an annular upper die. 2. The flange bolt forming die according to claim 1, wherein an escape angle β for forming scraps of the flange portion is formed on the outer peripheral portion of the annular projection. 3. The flange bolt forming method according to claim 1, wherein the surface roughness of the upper die is within 0.3a, and the clearance angle α of the cutting edge for forming the bolt head of the upper die is approximately 0 °. dice.