JPS58122146A - Block-forging method of bevel gear or the like - Google Patents

Abstract

PURPOSE:To manufacture a bevel gear, etc. of a good shape having no defect, by forging force of a small load, by making a forging blank material flow along the forging surface by forging it by a punch, etc. having a forging surface of a crest shape, and filling it up to the outside end part of a cavity. CONSTITUTION:In a metallic die 4 for manufacturing a bevel gear 2 by block- forging a forging blank material 12 in a cavity 9 formed by upper and lower metallic dies 5, 6, and punches 7, 8, a forging surface 10 of the upper punch 7 of the gear 2 side is formed so that the face angle is about 60-160 degrees desirably, and further desirably, in the crest shape like a cone of an obtuse angle, this upper punch 7 is made to descend onto the forging blank material 12 being in a hot state, which is loaded on the lower punch 8 having a flat head, and the upper metallic die 5 is made to tightly adhere to the lower metallic die 6. Subsequently, the lower punch 8 is made to ascend and the forging blank material 12 is forged. The forging blank material 12 flows smoothly to the outside end part along the forging surface 10, forms a back cone surface 3 of a gear 1, and the bevel gear 1 having no defect is obtained by a small forging load.

Description

[Detailed description of the invention] The present invention relates to a closed forging method for bevel gears and the like.

The closed forging method is an extremely efficient production method that can mass produce products with complex shapes at high speed. However, when forging the bevel gear 2 in which the teeth 1 protrude from the outside as shown in Fig. 1, under the forging force within the permissible range of the punch, the outer end, especially the internal conical surface 3, may be underfilled. Therefore, it is not possible to form a good shape, and in order to form a good shape without underfilling, the forging force of the punch must be increased beyond the allowable range. Ta. Therefore, the durability of the mold and punch cannot be obtained, and it has been difficult to practically perform closed forging of a good bevel gear without underfilling.

The present invention was developed in view of the above-mentioned points, and the forging pressure of the conventional flat-headed punch creates a shape that restricts the flow of the forging material at the root of the tooth of the bevel gear, thereby reducing flow resistance. By eliminating the increase in size, the forging material can be smoothly filled up to the outer end of the cavity, and the forging force of the punch can be applied to the conical surface of the stomach at the outer end with a small load within the allowable range. To provide a closed forging method for bevel gears, etc., which can practically mass-produce bevel gears having a desired shape without causing underfilling.

Hereinafter, the present invention will be explained based on examples.

FIG. 2 shows an example of a bevel gear 2 forged according to the present invention, in which the inner conical surface 8 of a portion of the tooth 1 does not have underfilling as shown in FIG.
It can be molded into the desired shape.

FIG. 8 and subsequent figures show an embodiment of the present invention, which is an example of closed forging of the bevel gear 2 as shown in FIG. 2 above.

The mold 4 is an upper mold 5 which is divided into upper and lower halves by one tooth of the bevel gear 2.
and a lower mold 6, and an upper punch 7 and a lower punch 8 are freely retractable in the center of each, and a desired bevel gear 2 is formed.
The cavity 9 can be formed. The forging surface 10 of the upper punch 7 of the upper mold 5 @ for forming the upper part of the bevel gear 2 is formed into an obtuse conical shape with an apex angle of 120 degrees as shown in the figure. is widened to allow the flow of the forging material 12 to flow smoothly to the outer end of the cavity 9 along the raised forging surface 10 without being narrowly constricted. The lower punch 8 has a normal flat head shape, and is used to shape the shaft portion 18 of the bevel gear 2 and press the forged material 12 to the outer end of the cavity 9 so that it flows.

An example of closed forging of the bevel gear 2 will now be described. The die 4, the upper bonder, and the lower punch 8 are mounted on a specified forging press (not shown), and the forged material is made into a warm-shaped neck and a nine-cylindrical shape as shown in Fig. 8! 2 is placed on the lower punch 8 which is retracted downward and housed in the cavity 9. and,
As shown in FIG. 4, the upper die 5 and the upper punch 7 are lowered to bring the upper die 5 into close contact with the lower die 6, and the forging material 12 is first forged with the forging surface 10 of the upper punch 7. At this time, the forged material 12 is
As shown in the figure, one end is conically depressed and slightly bulges toward the outer periphery of the cavity 9, etc. Next, when the lower punch 8 is raised and the forging material 1.2 is forged, the forging material 12 shrinks to form a shaft portion 18 as shown in FIG. 5, and flows toward the outer periphery of the cavity 9. Since the forging surface 10 of the upper punch 7 has a conical height shape, the root portion 11 of the tooth 1 does not become narrow as shown in FIG. The gas flows smoothly along the axis toward the outer end, and the conical surface 8 of the bevel gear 2 can be reliably formed. Therefore, the forging force of the lower punch 8 can be set to a small load within the allowable range, and even though the forging force is small, the conical surface 3 in the stomach does not become underfilled as in the conventional case, and the forging force as shown in FIG. A bevel gear 2 having a good desired shape can be forged. When the lower punch 8 finishes forging, the upper die 5 and the upper punch 7 are raised as shown in Fig. 6, and the lower punch 8 is further raised to carry out the forged bevel gear 2 and then the next forged material 12. Accommodate KIiFII as above
It is E-forged. Note that the shaft hole machining is performed in a later process.

In the above example, the outer diameter of the warm koji at 800 to 500°C is 86
When forging a bevel gear with an outer end diameter of 65 mm from a forged material of 1111, in the conventional method, the compressive stress of the punch is 800 ~
The stress of Amano, which was above, is 180 to 206'Ka, which is a sufficiently small stress within the allowable range, and a reduction of 40% has been achieved, improving the durability of molds and punches for mass production of bevel gears. It can be fully put into practical use.

In the above example, the forging surface of the upper punch was made into a conical height shape with an apex angle of 120 degrees, but even if the apex angle was set to 60 degrees, the forging force would still be within the allowable range. Although it depends on the situation, an apex angle in the range of about 60 to 160 degrees, preferably an obtuse angle range, can be sufficiently put into practical use.

Also, the shape of the forging surface of the upper punch is not limited to a conical shape, but can also be a high shape that is easy to process, such as a mountain shape or a spherical shape. It is more preferable to have an optimal shape.

Furthermore, if the forging force of the lower punch is set so that the forging material comes into contact with the outer end surface of the back conical surface of the bevel gear in the cavity, the forging pressure can be further reduced and the durability of the die and punch can be improved. be.

In addition, although the upper punch is separate from the upper mold to press the forged material, it is also possible to form a forging surface such as a punch integrally with the upper mold and perform the forging process. .

As mentioned above, it is preferable that the forging surface on the gear side of the bevel gear has a raised shape, but there is no way to prevent the forging surface of the lower punch on the opposite side from also having a predetermined conical or other raised shape. do not have.

In the above embodiments, the forged product has been described as a bevel gear, but the present invention can be similarly applied to a crown gear or other products having a gear or the like protruding from the outside.

According to the present invention, cold forging, which was previously impossible with the closed forging method described above, can be performed within a predetermined tolerance range by setting the apex angle of the forging surface to an appropriate angle as described above. Items that can be closed-forged using forging pressure, such as bevel gears, closed in a cold state! Forging can also be put to practical use.

As described above, in the present invention, it is possible to eliminate the flow of the forging material from becoming constricted at the root of the teeth of the bevel gear, which increases the flow resistance, and allows the forging material to flow smoothly all the way to the outer end of the cavity. It can be filled with a small load that keeps the forging force of the punch within the allowable range, and the back conical surface of the bevel gear does not become underfilled.
This makes it possible to practically mass-produce bevel gears and the like having a desired shape.

[Brief explanation of drawings]

Figure 1 shows a conventional bevel gear closed! [Side sectional view of forged product,
FIG. 2 is a side sectional view of an example of one-block forging of the bevel gear of the present invention;
FIGS. 3 to 6 are side sectional views of essential parts for explaining each process of closed forging according to the embodiment described above. 1... Teeth, 2... Bevel gear, 8... Back conical surface, 4
... Mold, 5... Upper mold, 6... Lower mold, 7...
- Upper punch, 8... Lower punch, 9... Cavity,
10... Forging surface, ■... Root part, ■2... Forging material. Applicant Kawasaki Oil Industries Co., Ltd. Agent Patent Attorney Kuniaki Morimoto

Claims (1)

[Scope of Claims] (1) In a closed forging method for bevel gears, etc., in which a forging material is collected in a predetermined cavity formed by a die and a punch, and the cavity KIIi forging material is forged-filled, Press the forged material with a punch, etc. with a forging surface of
It is characterized by forging the forging material so that it flows along the forging surface of a punch or the like having a conical or other raised shape and filling the outer end of the cavity such as the conical surface of the bevel gear. Closed forging method for bevel gears, etc. C) The forging surface of the gear side of the bevel gear to be forged or the forging surface of the die is shaped like a cone, etc., and the punch opposing the forging surface is used to press the forging material with a forging force within an allowable range. Closure of bevel gears, etc. listed in scope 1! III Manufacturing method. (8) A closed forging method for bevel gears and the like according to claim 1 or 2, in which the forging surface is forged with a punch or the like having a conical or other raised shape with an apex angle of about 60 to 160 degrees. (Forging method for closed forging of bevel gears, etc. as described in Claim 1 and 2, in which the forging surface is forged with a punch or the like having a raised shape such as a conical shape with an obtuse apex angle. Can) Forging material A closed forging method for a bevel gear or the like according to any one of claims 1 to 4, wherein the forging material is forged with a load such that the forging material comes into contact with the outer end surface of the conical surface of the bevel gear in the cavity.