JPH0683885B2 - Method for manufacturing forged product having non-circular flange - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is a forging having a non-circular flange portion and a shaft portion by forging by pressing a cylindrical billet having a constant cross section in the axial direction of the billet. The present invention relates to a manufacturing method for manufacturing a product. INDUSTRIAL APPLICABILITY The present invention can be utilized, for example, when manufacturing a shaft rear axle, a shaft differential side gear, etc. as a forged product.

[Prior Art] The material cost accounts for more than half of the manufacturing cost of the forged product. Therefore, the key to reducing the cost of the forged product is to improve the material yield. In order to survive in the forging industry in the increasingly competitive business competition,
Cost reduction by improving the material yield is the most important theme.

By the way, when forging a forged product with a circular flange by pressing a cylindrical billet with a constant cross section in the axial direction of this, due to the reason that the distribution of meat is relatively easy, , A closed forging method is used that uses a mold that eliminates the occurrence of flash. According to the closed forging method, the material yield can be improved by eliminating the outer flash, and the cost of the forged product can be reduced. However, the shape of the forged product that can use the closed forging method is limited, and when forging a forged product with a non-circular flange portion, for example, a castor rear axle, it is not the closed forging method, but the mating surface of the die. An open forging method is used to positively expose the outside flash. That is, since the flange portion has a non-circular shape, it is difficult to distribute the meat when forming the flange portion, and a lack of meat (a spatial defect formed without the material flowing into the mold cavity) is likely to occur. Therefore, a flash is positively provided between the mating surfaces of the molds, and due to the deformation resistance of the burr, it is blocked that the material being processed flows out, so that a defect of the wall thickness is less likely to occur.

According to the conventional open forging method adopted for such a reason, when manufacturing a forged product having a non-circular flange portion, in the first step, as shown in FIG. A spare lower mold 802 having a spare flange cavity 801 formed on the upper portion of the spare shaft cavity 800.
And a preliminary upper die 804 having a pressing portion 803 and a preliminary forging die 805 for open forging, which is used to press a billet having a constant cross section in the axial direction of the billet. Pre-forging with this, and as a result, the shaft center is
A non-circular preliminary flange portion 806 in which the outer diameter from 808a to the portion 806a and the outer diameter from the shaft core 808a to the portion 806b are different.
And the pre-forged product 808 formed on the shaft portion 807 is to be formed.

And in the second step after the first step, as shown in FIG.
Main forging lower die 912 having a shaft cavity 910 having substantially the same shape as the shaft 807 of the pre-forged product 808, and a flange cavity 911 formed in the upper part of the shaft cavity 910, and a book having the flange cavity 913. Forging upper die 914 and forging die 915 for open forging consisting of this forging die 915 for open forging.
Press the pre-forged product 808 in the axial direction of this to forge,
As a result, a forged product 918 having a non-circular flange portion 916 and a shaft portion 917 is formed.

By the way, preliminary forging die 805 for open forging in the 1st process, 2nd
In the above-mentioned conventional manufacturing method using the forging die 915 for open forging in the process, even when manufacturing a forged product having a non-circular flange portion that is apt to cause a wall defect, the occurrence of a wall defect is prevented. Although it can be suppressed, in the second step, which is the main forging step, an outer beam 919 having a considerably large width is generated around the non-circular flange portion 916 of the forged product 918, so that the material yield tends to be greatly reduced, and the forged product is likely to decrease. Was causing the cost increase. Further, if the material yield is increased and the occurrence of the outburst 919 is suppressed, there is a problem that the distribution of the meat in the non-circular flange portion does not work well, and the lack of wall defect easily occurs.

The outer flash 919 is removed using a deburring die in a deburring step as a third step performed after the second step.

[Problems to be Solved by the Invention] The present invention has been made in view of the actual circumstances of the above-described conventional manufacturing method, and an object thereof is, in a method for manufacturing a forged product having a non-circular flange portion, a defective wall defect. To provide a manufacturing method for manufacturing a forged product in which the material yield is improved while suppressing the above.

[Means for Solving Problems] The manufacturing method according to the present invention will be described with reference to the schematic diagrams shown in FIGS. 1 and 2, and is for a forged product having a non-circular flange portion and a shaft portion to be manufactured. The non-circular shape for forming a preliminary shaft portion cavity 10 that is a mold object with the shaft portion that molds the shaft portion, and a preliminary flange portion that is formed on the preliminary shaft portion cavity 10 and becomes the non-circular flange portion. A spare lower mold 1 having a preliminary flange cavity 11 having a flange width narrower than the maximum flange width of the flange portion, and a piston having a cross section substantially the same as that of the preliminary flange cavity 11 and fitted into the preliminary flange cavity 11. A preliminary upper die 2 having a circular pressing portion 20 and a closed preliminary forging die 3 consisting of a preliminary billet having a constant cross-section for pre-forging a cylindrical billet, and a preliminary flange portion 30.
First to make a pre-forged product 32 having (non-circular shape) and shaft 31
A step, a shaft cavity 40 having substantially the same shape as the shaft portion 31 of the preliminary forged product 32, and a non-circular flange portion formed on the shaft cavity 40 above the non-circular flange portion, which is a mold object. A first flange cavity 41 thinner than the thickness, and
A main forging lower die 4 having a second flange portion cavity 42 formed in an upper portion of the flange portion cavity 41 and protruding from the first flange portion cavity 41 in the outer circumferential direction, and the first flange portion cavity. 41, a first pressing portion 50 that is substantially a mold object, and a second pressing portion 51 that bulges like a shoulder on the outer peripheral surface of the first pressing portion 50 and has an outer peripheral shape that is substantially a mold object to the second flange cavity 42. Of the main forging upper die 5 having the above, and the main forging lower die 4 and the main forging upper die 5 are in a hermetically sealed state at the fitting portion, and the burr of the overhanging portion is prevented from becoming larger than a certain amount. The forging die 6 is used to forge the preliminary forged product 32 to make a forged product 7 having a non-circular flange portion 8 having an overhanging portion 80 on the upper peripheral edge.
It consists of steps.

In addition, you may implement the 3rd process of removing the overhang | projection part of the non-circular flange part of a forged product from a non-circular flange part after a 2nd process.

[Operation] According to the manufacturing method of the present invention, when the preliminary forged product is forged by the main forging upper die 5 and the main forging lower die 4 in the second step,
As shown in the figure, the forged product 7 having the protruding portion 80 is formed on the entire circumference or substantially the entire circumference of the non-circular flange portion 8. Here, in the overhanging portion 80, the height of the portion 80a is equal to that of the portion 80b.
Higher than the height of. The height of the portion 80a of the overhanging portion 8 is high because the outer diameter dimension from the shaft core O to the portion 80a is shorter than the outer diameter dimension from the shaft core O to the portion 80b. This is because it flows into the cavity 42 and projects.

[Effects of the Invention] According to the manufacturing method of the present invention, unlike the conventional method shown in FIGS. 14 and 16, a closed preliminary forging die 3 and an overhanging forging die 6 that do not cause external flash between the mating surfaces of the die. Since the conventional outer beam 919 can be formed as the projecting portion 80, the forged product having the non-circular flange portion can be manufactured while suppressing the amount of outer beam and improving the material yield as compared with the conventional one. can do.

Further, according to the manufacturing method of the present invention, in the second step, the overhanging forging die 6 in which the outer beam 919 is formed as the overhanging portion 8 is used instead of forming the resistance of the material flow by the conventional outer beam 919. At the same time, since the upper die 5 and the lower die 6 are in a hermetically sealed state without burrs, like the forging die for the open forging, the non-circular flange portion is provided while suppressing the occurrence of the wall thickness defect of the forged product. Forged products can be manufactured. or,
According to the manufacturing method of the present invention, the preliminary upper mold 2 is used in the first step.
Even if a vertical flash S (see FIG. 3) occurs at the boundary between the lower mold 1 and the preliminary lower mold 1, this vertical flash S becomes the overhanging portion 8 in the second step. Therefore, a forged product having no vertical beam S can be manufactured.

[Embodiment] FIGS. 7 to 13 show an embodiment in which the present invention is applied to a method of manufacturing a shaft rear axle having a non-circular flange portion. Each step will be described below separately.

(First Step) The first step is a step of forming a preliminary forged product by carrying out rough land forging, and roughly forcing the meat volume when forging the forged product.

The closed preliminary forging die 100 used in the first step is a preliminary lower die held by a first bolster (not shown) as shown in FIG.
110 and a preliminary upper mold 120 held by a first upper bolster (not shown). Here, the preliminary lower mold 110 includes molds 111 and 112. Note that FIG. 12 is a plan view of the preliminary lower mold 110.

The preliminary upper mold 120 includes molds 121 and 122. The spare lower die 110 includes a spare shaft portion cavity 117 and a non-circular spare flange portion cavity 11 formed on the spare shaft portion cavity 117.
8 and. Spare upper mold 120 is a spare flange cavity
It has a piston-like pressing portion 125 that fits in 118.

In the first step, the closed preliminary forging die 100 composed of the preliminary lower die 110 and the preliminary upper die 120 described above is used to press a cylindrical billet having a constant cross section in the axial direction of the billet to forge it. 9
As shown in the figure, the shaft portion 101 and the non-circular preliminary flange portion 102
A pre-forged product 103 consisting of and is formed. Here, the flange width dimension L1 of the preliminary flange portion 102 is narrower than the flange width dimension L2 of the non-circular flange portion 302. A vertical flash 102a is likely to occur around the outer periphery of the non-circular preliminary flange portion 102 of the preliminary forged product 103.

(Second Step) The overhanging forging die 300 used in the second step is for finishing forging. The main forging lower die 310 is held by a second lower bolster (not shown) and the lower forging die 310 is held by a second upper bolster (not shown). It consists of a main forging upper die 330. The main forging lower die 310 is the die 31
It consists of 1, 312. The main forging upper die 330 includes dies 331 and 332. The main forging lower die 310 includes a shaft portion cavity 320 having substantially the same shape as the shaft portion of the pre-forged product, and a non-circular first flange portion cavity 32 formed on the shaft portion cavity 320.
1 and a second flange portion cavity 322 formed above the first flange portion cavity 321. Note that FIG. 13 is a plan view of the main forging lower die 310.

The main forging upper die 330 has a first pressing portion 336 that is substantially the same as the first flange portion cavity 321, and further has a first pressing portion 3
The outer peripheral shape of the member 36 bulges like a shoulder, and the outer peripheral shape thereof has a second flange portion cavity 322 and a second pressing portion 337 which is substantially a mold object.

In the second step, with the shaft portion 101 of the preliminary forged product 103 formed in the first step set in the shaft portion cavity 320, the preliminary forged product 103 is pressed again in the axial direction by the overhanging forging die 300. Then finish forging. Then, the preliminary flange portion 10 of the preliminary forged product 103 is pressed by the first pressing portion 336 and the second pressing portion 337.
The second material deforms and flows laterally outward and flows into the second flange cavity 322. When the cavity 322 is filled with material, the resistance increases and the material fills every corner of the mold. As a result, the vertical beam 102a generated in the first step is overhanging part 301.
Therefore, as shown in FIG. 10, a forged product 303 having a non-circular flange portion 302 having a projecting portion 301 on the upper peripheral portion and having no non-circumferential defect is formed. The overhang portion 301 of the non-circular flange portion 302 is removed from the non-circular flange portion 302 by performing a deburring step using a deburring die after the second step. It should be noted that FIG. 11 shows a forged product 30 in which the protruding portion 301 is removed from the non-circular flange portion 302.
It is a vertical side view of FIG.

In the above-mentioned embodiment, unlike the conventional case shown in FIGS. 14 and 16, a forging die for so-called open forging in which a flash is generated between the mating surfaces is not used, and the closed preliminary forging die 100 and the overhanging forging die 300 are used. Since the conventional outer flash 919 can be formed as the overhang portion 301, the non-circular flange portion 302 can be formed while suppressing the amount of the outer flash as compared with the conventional one.
It is possible to manufacture a forged product 303 having Further, since the closed preliminary forging die 100 and the overhanging forging die 300 are used in the manufacturing method according to the present embodiment, similar to the manufacturing method using the forging die for open forging shown in FIG. 14 and FIG. The forged product 303 having the non-circular flange portion 302 can be manufactured while suppressing the generation of defects.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a closed preliminary forging die used in the first step, FIG. 2 is a vertical sectional side view of an overhanging forging die used in the second step, and FIG. 3 is preliminary forging in the first step. FIG. 4 is a vertical cross-sectional side view showing a state where FIG. 4 is a vertical cross-sectional side view showing a state in which final forging, that is, main forging is performed in the second step,
FIG. 5 is a plan view of the preliminary forged product preliminarily forged in the first step, and FIG. 6 is a plan view of the finish forged product, that is, the forged product in the second process. FIG. 7 is a vertical sectional side view of the closed preliminary forging die, FIG. 8 is a vertical sectional side view of the overhang forging die, and FIG. 9 is a preliminary forging in a state where the preliminary preliminary forging is performed using the closed preliminary forging die in the first step. FIG. 10 is a vertical cross-sectional side view of the product, FIG. 10 is a vertical cross-sectional side view of a forged product that is finish forged, that is, main forged by using an overhang forging die in the second step, and FIG. It is a side view. FIG. 12 is a plan view of a preliminary lower die of the closed preliminary forging die, and FIG. 13 is a plan view of a main forging lower die of the overhanging forging die. 14 to 17 show an open forging method according to the prior art, FIG. 14 is a vertical sectional side view of a main part of a preliminary forging die used in the first step, and FIG. 15 is a preliminary used in the first step. FIG. 16 is a plan view of a forged product pre-forged with a forging die, FIG. 16 is a vertical cross-sectional side view of a main part of the forging die used in the second step, and FIG. 17 is a forging forged by the forging die used in the second step. It is a top view of an article. 1 is a spare lower die, 10 is a spare shaft cavity, 11 is a spare flange cavity, 2 is a spare upper die, 20 is a piston pressing portion, 3 is a closed preliminary forging die, 4 is a main forging lower die, 40 is a shaft Part cavity, 41 is a first flange part cavity, 42 is a second flange part cavity, 5 is a main forging upper die, 50 is a first pressing part, 51 is a second pressing part, 6 is a forging die, 8 is an overhanging part Are shown respectively.

Claims (2)

[Claims] 1. A spare shaft cavity that is substantially a mold object for the shaft forming the shaft of a forged product having a non-circular flange to be manufactured and a shaft, and an upper portion of the spare shaft cavity. A preliminary lower die having a preliminary flange portion cavity having a width narrower than the maximum flange width of the non-circular flange portion so as to form a preliminary flange portion which is formed in the non-circular flange portion, and the preliminary flange. Part of a closed pre-forging die consisting of a preliminary upper die having a piston-like pressing portion that fits in the preliminary flange cavity and has a cross-section that is almost the same as that of the partial cavity. Pre-forging to make a pre-forged product having a pre-flange part and a shaft part, a shaft part cavity having substantially the same shape as the shaft part of the pre-forged product, and an upper part of the shaft part cavity. A first flange cavity that is formed to be a mold object with the non-circular flange and is thinner than the thickness of the non-circular flange, and is formed on an upper portion of the first flange cavity and protrudes outward from the first flange cavity. Main forging lower die having a second flange portion cavity having a wide cross-sectional shape, a first pressing portion that is substantially the same as the first flange portion cavity, and a shoulder-shaped outer peripheral surface of the first pressing portion. Second bulge whose outer peripheral shape is substantially the same as the second flange cavity.
A second step of forging the preliminary forged product with a main forging upper die having a pressing portion, and forging the preliminary forged product to form a forged product having a non-circular flange portion having an overhanging portion on the upper peripheral edge, For manufacturing a forged product having a non-circular flange portion made of. 2. A third step of removing the protruding portion of the non-circular flange portion of the forged product from the non-circular flange portion after the second step.
The manufacturing method according to claim 1, wherein the steps are performed.