JPS639897B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The forging die (hereinafter also simply referred to as a die) of the present invention can be used when cold forging bolts, etc. It can be used as a die for forging bolts, etc. to great effect.

[Prior Art] Conventionally, when manufacturing long bolts etc. by cold forging, especially when manufacturing bolts of multiple lengths with one die, a through-type die as shown in Fig. 1 was used. A was used.

This die A is generally used in which a straight-shaped nib B with a uniform outer diameter is press-fitted or shrink-fitted into a nib case C to apply horizontal stress to the nib B in a direction perpendicular to the die axis direction. ing.

This type of die A allows you to make bolts of various lengths (however, the outer diameter is the same) with one die, and there is no need to worry about changing dies, making it ideal for making a variety of bolts with different length dimensions. It is heavily used.

However, when making, for example, an M8 (8 mm diameter) bolt, a force of approximately 20 tons or more is applied to the bolt material set in the die A, which is the workpiece material, even with a normal bolt. Therefore, if this force exceeds the frictional force between nib B and nib case C applied to nib B of die A by press fitting or shrink fitting, nib B will move in the direction of the force from nib case C. In severe cases, the nib B could fall out of the nib case.

For this reason, we also proposed a method to solve the problem of the nib protruding from the nib case by gradually decreasing the diameter of the outer circumference from the die inlet end to the opposite end and forming a tapered surface on the outer circumference of the nib. It was done. However, with such a structure in which a tapered surface is formed on the outer periphery of the nib, it is not possible to make a double-sided die in which both ends of the die can be used. The entire nib must be formed with a thick wall so that sufficient strength can be obtained even in the thin part.
In the end, the size of the nib case also increased, leading to problems such as increased die production costs.

Furthermore, even if a part of the nib B, especially the part on the die inlet end side, wears out due to use, the nib B must be replaced, and this makes it difficult to replace the nib B made of cemented carbide.
There was also the problem of raising the running cost of the dice that use them.

[Object of the Invention] The object of the present invention is to solve the problem of the nib protruding outward from the nib case without increasing the size of the nib case, and to replace only the worn part when the nib wears out. The aim is to provide dice that make it possible.

[Structure of the Invention] The structure of the present invention for achieving the above object is as follows: In a penetrating forging die in which a cemented carbide nib is inserted into a cylindrical nib case, the nib is inserted into at least the die opening. The large-diameter nib is divided into a large-diameter nib that fits on the inner side of the die and a small-diameter nib that fits on the inside of the die, and the outer periphery of the large-diameter nib is formed into a tapered shape that gradually decreases in diameter from the die/opening to the inside of the die. The gist is a forging die with the following characteristics.

[Examples] Examples of the present invention will be described below with reference to the drawings.

First, FIGS. 2 and 3 show a forging die 1 according to a first embodiment of the present invention. In the figure,
2 is a nib case; 3 is a small-diameter cemented carbide nib (hereinafter also referred to as a straight nib) whose outer diameter is the same throughout the entire length and is press-fitted into the inside of the die; 4 is press-fitted into the die opening side・The fitted large-diameter cemented carbide nib (hereinafter also referred to as a taper nib) has an outer periphery that is gradually reduced in diameter from the die opening to the inside, and specifically has a tapered shape with a taper angle θ of about 30 minutes. is formed. Incidentally, the inner circumferential holes 5 of the straight nib 3 and the tapered nib 4 are both formed into a desired shape as in a conventional die.

The inner periphery of the nib case 2 is tapered to match the outer periphery shapes of the straight nib 3 and the tapered nib 4, and the tapered nib storage hole 2A into which the tapered nib 4 is fitted is tapered with approximately the same taper angle θ from the die opening to the inside. Further, the straight nib storage hole 2B into which the straight nib 3 is press-fitted is a straight hole whose inner diameter does not change. A step 6 is formed at the boundary between the straight nib storage hole 2B and the tapered nib storage hole 2A because the outer diameters of the straight nib 3 and the taper nib 4 are different. Incidentally, as a problem in processing the nib case 2, it is difficult to process each part of the tip of the tapered nib storage hole 2A of the nib case 2, so the inner diameter of the tip 7 is made larger than the outer diameter of the nib.

When processing bolt materials etc. using such a die 1, the roughly pressed bolt materials are set in the inner circumferential holes 5 of the straight nib 3 and the taper nib 4,
Punch with more force from the opening side of die 1. Then, the bolt material is forged and pressurized into the shape of the inner peripheral hole 5 of the nib. Even if a strong force is applied to the taper nib 4 of the die 1, the taper nib 4 and the taper nib storage hole 2A into which the taper nib 4 is fitted are formed in a tapered shape so that the diameter gradually decreases from the opening of the die 1. Therefore, the vertical force generated in the axial direction of the inner circumferential hole 5 is received by the sum of the reaction force generated on the tapered surface and the component force in the axial direction of the inner circumferential hole 5 of the frictional force, and the tip of the tapered nib 4 is Since the taper nib 4 is restricted by the second step 6, the taper nib 4 will not come out due to punching. Since no force is applied to the straight nib 3 in the axial direction of the inner circumferential hole 5 due to the action of the taper nib 4 and the step 6, it is sufficiently gripped and fixed to the nib case 2 by the normal press-fitting stress, and by punching. Therefore, the nib case 2 will not be pulled out.

Furthermore, if the nib is worn out during the forging process, in most cases the taper nib 4, which is subjected to a large force,
Since only the straight nib is worn out, use the straight nib 3.
Only taper nib 4 is inserted into die 1 by driving it out from the opposite end of die 1 to the opening side with a pin or the like.
By removing the tapered nib 4 and press-fitting a new taper nib 4, the die 1 can be used continuously, and there is no need to replace the entire nib or die 1 as in the past. It becomes possible to significantly reduce the running cost of Dice 1.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 shows an embodiment of a die that can be used on both sides, in which tapered nibs 11A and 11B of the same shape are provided at both ends of the die 10. At both ends of the nib case 12, tapered nibs 11A and 11B of the same shape are provided. Taper nib storage holes 13A and 13B are formed, and a straight nib storage hole 14 is formed between the two taper nib storage holes 13A and 13B.
Steps 15A and 15B are provided at the boundary between A and 13B, and the diameter of the straight nib storage hole 14 is smaller than the diameter of the inner end of the tapered nib storage holes 13A and 13B.

A straight nib 16 is press-fitted and fitted into the straight nib storage hole 14, and a taper nib 11 is inserted into each of the taper nib storage holes 13A and 13B.
A and 11B are press-fitted and fitted, and taper nib 1
1A and 11B have inner circumferential holes 17 of the desired processed shape.
A and 17B are bored, and the straight nib 14 has a straight inner circumferential hole 18 that communicates with the inner circumferential holes 17A and 17B. Incidentally, as in the first embodiment, the taper nib storage hole 13 of the nib case 12
The inner diameters of the inner tip portions 19A and 19B of A and 13B are larger than the outer diameter of the tips of the taper nibs 11A and 11B.

The die 10 of this embodiment configured in this way can be used in the same manner as the first embodiment, and can also be used with the taper nib 11.
Even if either one of the taper nibs 11A and 11B is worn out, the same die can be prepared immediately by turning the die 10 over.
If the shapes of the outer ends of the inner circumferential holes 17A, 17B are different from each other, it is possible to forge two different shapes with one die 10.

If the taper nib 11A or 11B of the die 10, which can be used on both sides, is worn out, the straight nib 3 can be easily replaced with the taper nib 4 by driving the straight nib 3 with a pin or the like, as in the above embodiment.
cannot be removed, but since the nibs are tapered, taper nibs 11A and 11B
One of the taper nib 11A or 11B can be easily pulled out by cutting out the inner periphery of the nib and using the cutout as a handhold.

In both the first and second embodiments shown above, a tapered nib and a straight nib are integrated, but in each embodiment, as shown in FIG. 5, a plurality of nib pieces 20 are combined, A mating nib 21 forming one nib may also be used.

[Effects of the Invention] As described above in detail, the forging die of the present invention divides the nib press-fitted into the nib case into two or more parts, a large-diameter nib and a small-diameter nib, and The nib has a large diameter, and its outer periphery is formed in a tapered shape that gradually decreases in diameter from the die opening to the inside of the die, and the inner peripheral holes of the large diameter nib and the small diameter nib are set to be concentric and have the same diameter.

Therefore, according to the present invention, the nib is not ejected outward from the die while the die is in use, and only the nib on the die opening side, which is particularly prone to wear, can be easily replaced, thereby improving the quality of the product. It is possible to prevent a decrease in the die and reduce the running cost of the dice.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional forging die;
Fig. 2 is a sectional view showing a forging die according to the first embodiment of the present invention, Fig. 3 is a plan view thereof, Fig. 4 is a sectional view similarly showing the second embodiment, and Fig. 5 is a sectional view showing the first embodiment. Alternatively, it is a plan view showing a case where a taper nib of another shape is used in the die of the second embodiment. 1, 10... Forging die, 3, 16... Straight nib, 4, 11A, 11B... Taper nib, 2
A, 13A, 13B...Taper nib storage hole.

Claims (1)

[Claims] 1. In a penetrating forging die in which a cemented carbide nib is inserted into a cylindrical nib case, the nib is fitted into at least a large-diameter nib that fits into the die opening side and the inside of the die. The large-diameter nib is divided into a small-diameter nib, and the outer periphery of the large-diameter nib is formed into a tapered shape that gradually decreases in diameter from the die opening to the inside of the die, and the inner peripheral holes of the large-diameter nib and the small-diameter nib are set concentrically and have the same diameter. A forging die characterized by: