JPH0555212B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a tooth profile sizing die for finishing a gear tooth profile of a roughly processed intermediate forming material to a predetermined dimensional accuracy by ironing.

<Conventional technology> In the forging process to form a member having multiple tooth profiles along the axial direction on the outer circumferential surface, such as the inner ring of a constant velocity joint or a spur gear, the overall shape is prepared in advance. In order to finish a moderately rough-processed intermediate molding material to a predetermined tooth profile accuracy, sizing molding is performed in which the tooth portions are ironed (ioning).

In this sizing molding, for example,
As disclosed in Publication No. 110831, it is common practice to position and place an intermediate forming material on a die for finishing forming (sizing), and push it from the axial end face toward the die with a punch. It is.

Conventionally, in the case of a product whose shape allows the above-mentioned intermediate forming material to be completely pulled out in the axial direction of the die, the meat flowing through ironing does not affect the effective meshing dimensions of the gears, In the case of an intermediate molded material having a shape in which a flange-like left-over portion is formed at one axial end of the molded product and cannot be pulled through, various problems have arisen when ironing is performed.

<Problems to be Solved by the Invention> That is, by completely pushing the intermediate forming material into the die, an unpressed part is formed in the molded product at the entrance of the die, but it is not pressed by pressing by ironing. The excess meat that was not cut flows on the surface of the material and is pressed against the unpressed portion. Here, the ironing allowance of the die is determined assuming the flow of this surplus meat, and the effective dimensional accuracy of the finished tooth profile is generally designed with the surplus meat included.

On the other hand, since the amount of wear on the intermediate molding die for molding the intermediate molding material increases with the number of shots, it is unavoidable that the finished dimensions of the molded product increase as the production volume increases. That is, as wear of the intermediate forming die progresses, the actual ironing allowance increases and the amount of surplus meat due to sizing increases, until there is no escape for it. As a result, excess meat gets caught between the sizing die and punch and protrudes from the entrance of the die, making it impossible to press through the specified stroke.
The effective dimensions of the teeth cannot maintain the desired accuracy.

Previously, intermediate forming dies were updated when the finished product fell outside of a predetermined accuracy range, but in order to improve product control accuracy, intermediate forming dies had to be updated frequently. This has become an obstacle to reducing manufacturing costs.

The present invention was devised in order to solve the problems of the prior art, and its main purpose is to improve the tooth profile of a gear member having a residual portion without increasing manufacturing costs. An object of the present invention is to provide a die for tooth profile sizing that is improved so that control accuracy can be maintained.

<Means for Solving the Problems> According to the present invention, this object is achieved by using an intermediate forming die in which the contour of the inlet end of the rough forming tooth profile is rounded or chamfered over almost the entire circumference. , a tooth profile having a finished tooth profile for ironing the roughly formed gear tooth profile in an intermediate forming material obtained by forging a partially pressed out part in the axial direction and a roughly formed gear tooth profile. A sizing die, in which a part of the tooth profile sizing die has an initial radius or chamfer formed in the intermediate forming die, in a portion extending around the entire circumference of the finished tooth profile at the inlet end of the tooth profile sizing die. This is accomplished by providing a tooth profile sizing die that is characterized by a larger radius or chamfer.

<Function> By doing this, the radius or chamfer formed at the opening of the sizing die over almost the entire circumference will prevent the pressing of the intermediate forming material formed by the intermediate forming die during the intended shot. This is larger than the radius or chamfer of the remaining corners. That is, the cavity formed by chamfering the opening of the sizing die ensures a place for the meat flowing in the axial direction to escape when the intermediate forming material is pushed into the die. Therefore, even if excess metal increases due to wear of the intermediate forming die, the capacity to absorb the excess metal increases within a range that does not affect the effective dimensional accuracy, so the service life limit of the intermediate forming die can be increased. Can be extended.

<Examples> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 schematically show the main parts of a sizing device constructed based on the present invention.
This sizing device consists of a push-in punch 2 provided on a movable platen 1 of a forging press, and a die 4 and a knockout punch 5 provided on a fixed platen 3 of the press.

The push punch 2 is fixed to the movable platen 1 via a punch holder 6, and is displaced along a predetermined axis (vertical direction in this embodiment) by driving the movable platen 1. has been done.

The die 4 has a finished tooth profile 7 formed on its inner peripheral surface, and is fixed to the fixed platen 3 via a die holder 8.

The knockout punch 5 includes a guide ring 9 that is slidably engaged with the die 4 and the die holder 8 in the axial direction, a knockout 10 that is received in the guide ring 9 so as to be slidable in the axial direction, and a knockout 10 that is axially slidably engaged with the die 4 and the die holder 8. It consists of a knockout pin 11 for protruding in the direction.

The first upper end 9a of the guide ring 9 is reduced in diameter so that it can relatively tightly engage with the center hole 13 of the intermediate forming material 12, which has a rough-machined gear tooth profile used for, for example, a pinion gear of a transmission. It's like that. Further, the upper end surface 10a of the knockout 10
is the shoulder portion 13a of the center hole 13 of the intermediate forming material 12.
is in contact with.

A cushion member 14 made of urethane resin or the like is interposed between the guide ring 9 and the fixed plate 3, so that the guide ring 9 is constantly biased upward in FIG. has been done.

As shown in FIG. 3, on the inlet side of the die 4, a chamfer 20 is formed substantially uniformly over the entire circumference of the opening of the finishing tooth profile 7, and widens toward the opening end face side. As shown in FIG. 4, the diameter of the tip of the finished tooth profile 7 of the die 4 indicated by the solid line is d1 compared to the diameter of the tip of the rough tooth profile 12a of the intermediate forming material 12 indicated by the imaginary line. The diameter of the bottom of the finished tooth profile 7 is set to be larger than the diameter of the bottom of the rough tooth profile 12a by d2. In other words, when the intermediate forming material 12 is pushed into the die 4, the tooth top surface 21 is squeezed by d1, but the tooth bottom surface 22 is not squeezed because a gap c1 is created between it and the finished tooth profile 7. .

Further, the thickness dimension of the tooth end portion is approximately equal to the finished tooth profile 7 of the die 4 shown by the solid line and the rough tooth profile 12a of the intermediate forming material 12 shown by the imaginary line, but the thickness dimension of the tooth root portion is as follows. The rough tooth profile 12a of the intermediate molding material 12 shown by the imaginary line is larger than the finished tooth profile 7 of the die 4 shown by the solid line. Therefore, the ironing distance of the tooth surface 23 is shown in Fig. 4.
As shown in the dimensions d3 to d5, the root side is larger, and the squeezing allowance gradually decreases toward the tooth tip, so that there is almost no squeezing at the tooth tip.

Next, the ironing process in the above embodiment will be explained.

First, while the movable platen 1 is sufficiently raised together with the indentation punch 2, the center hole 13 of the intermediate forming material 12 having the rough tooth profile 12a whose external contour has been adjusted in advance and which has been roughly machined is drilled. It fits into the upper end 9a of the guide ring 9, and the finished tooth profile 7 of the die 4.
The rough surface shape 12a of the intermediate molding material 12 is phase-aligned with respect to the rough surface shape 12a of the intermediate forming material 12. At this time, the lower end of the rough tooth profile 12a of the intermediate forming material 12 and the upper end of the finished tooth profile 7 of the die 4 are either slightly engaged with each other at the slope of the chamfer 20 as shown in FIG. However, it is better that at least the axially inner end surface 12b of the intermediate molding material 12 and the upper end surface 9b of the guide ring 9 are in close contact with each other from the beginning.

Next, when the push punch 2 is lowered together with the movable platen 1, the lower surface 2a of the push punch 2 and the upper surface 12c of the intermediate forming material 12 come into contact. At this time, since the intermediate molding material 12 is elastically supported floating in the axial direction via the guide ring 9, the reaction force of the cushion member 14 causes the intermediate molding material 1
Before the punch 2 is pushed into the die 4, the lower surface 2a of the push punch and the upper end surface 12c of the material are accurately brought into close contact.
As a result, the upper end surface 1 of the material relative to the axis of the die 4
The squareness of 2c is corrected (Figure 1).

From this, when the push-in punch 2 is further lowered against the pressing force of the cushion member 14, the intermediate forming material 12 is guided by the chamfer 20 uniformly applied to the introduction part of the finishing tooth profile 7, and the push-in punch 2 is moved. It is pushed into the die 4 while being held between the guide ring 9 (FIG. 2). Therefore, intermediate molding material 1
2 is held correctly, and at the same time, since the inner periphery of the center hole 13 is restrained by the upper end 9a of the guide ring 9, the toothed portion is prevented from being distorted inward.

When the intermediate forming material 12 is pushed in, the surface of the material is squeezed according to the difference between the material contour and the outline of the die 4, but as the material is squeezed, the flesh of the tooth surface 23 is squeezed between the die 4 and the intermediate forming material 12. Depending on the setting of the ironing allowance, it flows in one direction from the end of the tooth to the root of the tooth. As a result, the directionality of the surface texture becomes constant, so there is no interference with the flow of the texture, so it is expected that the surface roughness will stably improve. In addition, the comparatively important tooth tip diameter can be squeezed with the finishing tooth profile 7 to achieve a certain level of precision, and while the surface structure is compressed by ironing, the excess meat that has flowed down the tooth surface is It mainly flows into the cavity c1 at the bottom of the tooth, so it does not protrude. Also, the meat is pushed out in the axial direction,
As shown in FIG. 5, the radius of the corner of the rough tooth profile 12a and the flange portion 24 formed as a leftover portion at one axial end of the intermediate forming material 12 obtained in the initial shot is larger than that of the die. Since the chamfer 20 formed at the open end of the die 4 is sufficiently large, the void formed in this part when the intermediate forming material 12 is fully pushed into the die 4 (the position shown by the imaginary line) 〓Excess meat is absorbed by flowing into c2.

By the way, since the amount of wear on the die for molding the intermediate molding material 12 increases with the number of shots, the finished dimensions of the product increase as the production volume increases. That is, as the die for forming the rough tooth profile 12a wears down, the actual ironing allowance increases, and the amount of surplus meat due to ironing increases, eventually leading to a situation where there is no escape for it. As a result, excess meat is caught between the die 4 and the push-in punch 2 and protrudes from the entrance of the die 4.
It may become impossible to complete the prescribed stroke, and the effective dimensions of the teeth may no longer maintain their initial accuracy. In the present invention, a chamfer 20 larger than the initial round formed over the entire circumference of the outline of the rough forming tooth profile is formed at the entrance of the die 4 and at the entrance end of the intermediate forming die (not shown). As a result, the period until the surplus meat that has no place to escape curls up or becomes burrs, and the intermediate forming material 12 cannot be completely pushed into the die 4, is extended. Ru.

After the pushing is completed, move the movable platen 1 together with the pushing punch 2.
When raised, the finished product 12 is released from the die 4 due to the reaction force of the cushion member 14. Next, by protruding the knockout pin 11 using a drive means (not shown), the material 1 is removed.
2 is removed from the guide ring 9 as a completed product.

<Effects of the Invention> As described above, according to the present invention, in the process of forming a gear having a shape that has a residual portion at the end in the axial direction and cannot be pulled out as shown in the above embodiment,
Even if the intermediate forming die wears out and some amount of sag occurs in the unpressed portion of the intermediate forming material, the excess material can be absorbed by the void formed by the chamfering of the finished tooth profile, so it is especially suitable for intermediate forming. This is effective in extending die service life.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a state in which a material is set in a tooth profile sizing device based on the present invention. FIG. 2 is a cross-sectional view similar to FIG. 1 showing the state when processing is completed. FIG. 3 is an enlarged perspective view partially showing the introduction part of the finished tooth profile. FIG. 4 is an explanatory diagram showing the relationship between the rough tooth profile and the finished tooth profile. FIG. 5 is an enlarged cross-sectional view of essential parts showing the relationship between the intermediate forming material and the die at the start of the laddering process. 1...Movable plate, 2...Pushing punch, 2a...
Lower surface, 3... Fixed plate, 4... Die, 5... Knockout punch, 6... Punch holder, 7... Finished tooth profile, 8... Die holder, 9... Guide ring, 9a... Upper end, 9b ...Top end surface, 10...
Knockout, 10a... Upper end surface, 11... Knockout pin, 12... Intermediate molding material, 12a...
...Rough tooth profile, 12b...Inner end surface, 12c...Top surface,
13... Center hole, 13a... Shoulder, 14... Cushion member, 20... Chamfer, 21... Tooth tip surface,
22...Tooth bottom surface, 23...Tooth surface, 24...Flange part (remaining part).

Claims (1)

[Scope of Claims] 1. An unpressed portion 24 at one end in the axial direction is formed by an intermediate forming die in which the outline of the entrance end of the rough forming tooth profile is rounded or chamfered over almost the entire circumference.
A tooth profile sizing die 4 having a finishing tooth profile 7 for ironing the roughly formed gear tooth profile in an intermediate forming material 12 formed by forging a roughly formed gear tooth profile 12a. , a radius or chamfer larger than the initial radius or chamfer formed in the intermediate forming die is formed at the inlet end of the tooth profile sizing die over approximately the entire circumference of the profile of the finished tooth profile. A die for tooth profile sizing characterized by the following: