JPH08174131A - Full enclosed die forging of stepped extended shaft parts - Google Patents

Abstract

PURPOSE: To prevent, the generation of under-fill in a level difference part and to improve the die life at the time of forging a a stepped extended shaft material provided with a shaft part having difference between levels of a large diameter part and small diameter part by full enclosed die forging by controlling a rough forged shape within a certain dimension. CONSTITUTION: The level difference part 23 is formed on formed goods 20 by rough forging for the stepped extended shaft forged material and also the length of the small diameter part 22b is formed shorter by S×a<2> /b<2> to the finished dimension. (Where, S: the forming stroke in the finishing stage, a: the finished diameter of the large diameter part, b: the finished diameter of the small diameter part). When a cup-shaped head part 2 is made by full enclosed die forging using this rough forged formed goods 20, since the level difference part 23 is already formed in the rough forging stage, under-fill is never generated. Simultaneously, the length (h) of the small diameter part 22b of the formed goods 20 by rough forging is taken the forming stroke S in the finishing stage and finished dimensions a, b into consideration, so under-fill is not also generated at the tip of the shaft part. Forming pressure at the time of forming them is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed forging method for forging a material in a closed state in a mold, and more specifically, it forms a part having a stepped long shaft by the closed forging method. The present invention relates to a closed forging method for a stepped long shaft part used for cutting.

[0002]

2. Description of the Related Art Closure forging is a processing method of filling a material into an impression by pushing a punch into the material in a state where the material is confined in a mold, which improves yield, omits processing, and improves product accuracy. Therefore, it is widely used for manufacturing, for example, automobile parts.

When a part having a long shaft portion with a step is formed by such closed forging, one of the following methods has been adopted. (1) In the rough land process, as shown in FIG. 5, the shaft U is formed without steps, and the shaft length L is made approximately equal to the shaft length of the product from the viewpoint of preventing thinning of the shaft tip. Mold. Then, the step portion is formed in the finishing process. (2) In the wasteland process, as shown in FIG.
Also, the shaft length L is molded almost according to the product shape, and only the product dimension is finished in the finishing process.

[0004]

However, the above-mentioned conventional molding methods have the following problems, respectively. The elimination of such problems improves the quality of the closed forged product and the die. It was an issue to reduce the cost and the unit price of the product.

(1) In the first method of forming the step portion in the finishing step, the shaft portion U is thickened by the axial pressure in the finishing step to form the step portion. As shown in FIG. 7, a wall thickness is likely to occur in the step W, and this tendency becomes more remarkable as the difference in shaft diameter between the large diameter side and the small diameter side in the step W is large. (2) In the second method of forming the product substantially in the shape of the product in the waste land process, in the waste land process, the raw metal is first filled in the thick shaft portion X of the waste land mold shown in FIG.
Next, since the raw material metal flows from the thick shaft portion X into the thin shaft portion Y, a particularly high pressure is applied to the waste land mold as compared with the case where a shaft portion having no step is formed, and the material is Since the metal flows violently, the stepped portion Z of the rough land mold is likely to be worn and the mold life is shortened.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional closed forging method for a stepped long shaft component, and it is possible to prevent the occurrence of wall deficiency and improve the product accuracy. Moreover, it is an object of the present invention to provide a closed forging method for a stepped long shaft component that can improve the life of the die.

[0007]

A closed forging method for a stepped long shaft component according to a first aspect of the present invention comprises:
When molding a part that has a shaft that has a step between the large-diameter part and the small-diameter part, the step is formed on the rough-formed product in the rough process, and the length of the small-diameter part of the rough-formed product is finished. The closed forging method according to claim 2 is an embodiment of the closed forging method for a stepped long shaft part according to the present invention, in which the length of the small diameter portion of the rough formed product is compared with the finished size. , S × a ² / b ² (where S is the forming stroke of the finishing step, a is the finishing diameter of the large diameter portion, and b is the finishing diameter of the small diameter portion). The configuration of such a closed forging method for a stepped long shaft component is used as means for solving the above-mentioned conventional problems.

[0008]

In the closed forging method for a stepped long shaft component according to the first aspect of the present invention, since the step portion is formed in the roughing process, the step portion is not chipped. Further, since the small diameter portion of the shaft portion to be formed in the roughing process is formed to be short, it is not necessary to increase the molding pressure, the abrasion of the rough land mold is reduced, and the mold life is improved.

Further, in the closed forging method according to claim 2 as an embodiment of the closed forging method for the stepped long shaft part according to the present invention, the forming stroke S in the finishing step,
Since the length of the small diameter portion of the rough formed product is determined based on the finishing dimensions a and b of the step, it is possible to secure a sufficient amount of the raw material metal to flow into the small diameter portion of the finishing die, and especially for the lack of wall thickness. This prevents the occurrence of wall thickness at the tip of the shaft.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

1 to 4 are for explaining an embodiment of a closed forging method for a stepped long shaft part according to the present invention, and FIG. 1 (a) is a step formed in the embodiment. Sectional drawing showing the finished shape and dimensions of the attached long shaft part, FIG.
(B) is a cross-sectional view showing the shape and dimensions of a waste molded article for finishing to the above shapes and dimensions.

That is, the stepped long shaft component 1 shown in FIG. 1 (a) comprises a cup-shaped head portion 2 and a shaft portion 3 extending downward from the head portion 2. Includes a large diameter portion 3a and a small diameter portion 3b, and has a step portion 4 between the large diameter portion 3a and the small diameter portion 3b.

The dimension of each part of the stepped long shaft component 1 in this embodiment is a (diameter of large diameter part) = 40 m.
m, b (diameter of thin portion) = 30 mm, h (length of thin portion) =
90 mm, c (cup depth) = 40 mm, d (head size) = 40 mm, e (distance from outer edge of head to step 4) = 90 mm.

The closed forging procedure of the stepped long shaft component 1 having the above size and shape will be described below with reference to FIGS.

First, in the upsetting process shown in FIG.
The cylindrical material 10 heated to about 1200 ° C. is placed on the lower die 11 of the upsetting press (see FIG. 2A), and the upper die 12 is placed.
Is lowered to upset the material 10 into a barrel shape for descaling (see FIG. 2B).

Next, in the wasteland process shown in FIG. 3, the raw material 10 which has been barrel-shaped by upsetting is loaded into the lower die 13 of the wasteland type. Then, as shown in FIG. 3A, the upper die 14 of the waste land mold is pushed down by pushing up the molding punch 15 arranged on the lower die 13 side in a state where the upper die 14 of the waste land mold is lowered. , Lower mold 13 and forming punch 15
The material 10 is filled in the closed space formed by, and the waste molded article 20 is molded as shown in FIG.

As shown in FIG. 1 (b), this rough land molded product 20 is similar to the stepped long shaft component 1 shown in FIG. 1 (a).
A head portion 21 and a shaft portion 22 composed of a large diameter portion 22a and a small diameter portion 22b are provided, and a step portion 23 is formed between the large diameter portion 22a and the small diameter portion 22b. Here, regarding the dimensions of the rough land molded product 20, the diameters a ′ and b ′ of the large diameter portion 22a and the small diameter portion 22b are set in order to secure the locating property from the rough land mold to the finishing mold as shown in FIG. ), The finishing diameters a (40 mm) and b (30 m) of the stepped long shaft component 1
m), which is slightly smaller than m), and is 39.5 mm and 29.5 mm, respectively. Further, the cup depth c ′ of the head portion 21 is 20 mm, and the distance e ′ from the outer edge portion of the head portion to the step portion 23 is the same as the finishing dimension, which is 9 mm.
It is 0 mm.

Further, regarding the length h'of the small-diameter portion 22b, the forming stroke S described in the next finishing step will be described.
However, the difference in cup depth before and after finishing, that is, 20mm
Since it is (e−e ′), the finished length h (90 mm) is shortened by S × a ² / b ² , that is, 35.6 mm, and h ′ = 54.4 mm. .

Therefore, in forming the rough terrain, it is possible to mold the rough terrain molded product 20 without increasing the molding pressure, so that the service life of the rough terrain mold is extended as compared with the case where the small diameter portion is molded according to the finish dimension. Can be made.

In the rough terrain process shown in FIG. 4, the rough terrain molded product 20 molded to the above dimensions is transferred to the lower mold 16 of the finishing mold shown in FIG. 4, and as shown in FIG. 4 (a). , With the upper die 17 of the finishing die lowered,
The forming punch 18 arranged on the side of the
By pushing down at 20 mm, the stepped long shaft component 1 having the finished size is molded as shown in FIG. 4 (b).

At this time, since the step portion 23 has already been formed in the rough land process, there is no lack of wall thickness, and the length h'of the small diameter portion 22b of the rough land molded product 20 is determined by the forming stroke S and the finish dimension of the finishing process. Since a and b are taken into consideration, there is no occurrence of wall thickness at the tip of the shaft portion of the finished stepped long shaft component 1.

[0022]

As described above, according to the first aspect of the present invention.
In the closed forging method of the stepped long shaft part according to, since the step portion is formed in the roughing process and the small diameter portion of the shaft portion is formed short, it is possible to prevent the step portion from being thinned, Since the molding pressure can be reduced, a very excellent effect that the life of the mold can be extended is brought about. Also, in the closed forging method according to claim 2 as an embodiment of the closed forging method for a stepped long shaft part according to the present invention, in the rough forging part based on the workability applied in the finishing step and the finished size of the forged part. Since the length of the small diameter part of the molded product is determined, it is possible to flow the raw material metal into the bottom of the small diameter part of the finishing die without excess or deficiency, and especially to effectively prevent the occurrence of wall thickness at the tip of the shaft. It has an extremely excellent effect of being able to.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view showing a finish shape of a forged part formed in an embodiment of a closed forging method for a stepped long shaft part according to the present invention. FIG. 1B is a cross-sectional view showing a rough shape for finishing the forged part having the shape shown in FIG.

2 (a) and 2 (b) are explanatory views showing an upsetting step in an embodiment of a closed forging method for a stepped long shaft part according to the present invention.

3 (a) and 3 (b) are explanatory views showing a rough land process in an embodiment of a closed forging method for a stepped long shaft part according to the present invention.

4 (a) and 4 (b) are explanatory views showing a finishing step in one embodiment of the closed forging method for a stepped long shaft part according to the present invention.

FIG. 5 is a cross-sectional view showing an example of the shape of a waste molded article used in closed forging of a conventional stepped long shaft component.

FIG. 6 is a cross-sectional view showing another example of the shape of a waste molding used in closed forging of a conventional stepped long shaft component.

FIG. 7 is a schematic explanatory view showing defects that occur in the closed forging of the conventional stepped long shaft component.

FIG. 8 is a cross-sectional explanatory view showing the shape of a waste land mold used in conventional closed forging of a stepped long shaft component.

[Explanation of symbols]

 1 Stepped long shaft part 3 Shaft part 3a Large diameter part 3b Small diameter part 4 Step part 20 Waste land molded product 22b (For waste land molded product) Small diameter part 23 (For waste land molded product)

Claims (2)

[Claims] 1. When forming a part having a shaft portion having a step portion between a large diameter portion and a small diameter portion by closed forging, the step portion is formed in a waste land formed product in a waste land process and the waste land is formed. A closed forging method for a stepped long shaft component, characterized in that the length of the small diameter portion of the molded product is formed shorter than the finishing dimension. 2. The closed forging method for a stepped long shaft component according to claim 1, wherein the length of the small diameter portion of the rough-molded article is shortened by S × a ² / b ^{2 with} respect to the finish dimension. (However, S: forming stroke of finishing step, a: finishing diameter of large diameter portion, b: finishing diameter of small diameter portion).