JPH072258B2 - Tooth profile sizing die - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tooth profile sizing die for finishing a gear tooth profile of a rough-processed intermediate forming material to a predetermined dimensional accuracy by ironing.

[0002]

2. Description of the Related Art Like inner rings and spur gears of constant velocity joints,
In the forging process for forming a member having a plurality of tooth profiles along the axial direction on the outer peripheral surface, in order to finish the intermediate forming material roughly machined to the extent that the entire shape is adjusted in advance to a predetermined tooth profile accuracy Sizing molding is performed by ironing (ioning) only the teeth.

In this sizing molding, as disclosed in, for example, Japanese Patent Laid-Open No. 62-110831, an intermediate molding material is positioned and placed on a die for finish molding (sizing), and its axial end surface is placed. It is common to push from the die to the die.

As is well known, this ironing process is
It is carried out by press-fitting the intermediate molding material into a sizing die having an inner contour somewhat smaller than the outer contour of the intermediate molding material, but conventionally, the ironing allowance for the intermediate molding material, that is, the dimensional difference before and after processing, It was customary to expect a nearly uniform distribution over the entire circumference of the contour.

[0005]

However, when the ironing process is performed using a die whose dimensions are set so that the ironing allowances are equal over the entire circumference of the tooth profile of the meshing gear, a general gear tooth profile has a tooth root. Since the tooth thickness of the part is larger than the tooth thickness of the end part, internal strain due to compressive stress becomes uneven between the root part and the end part, and it is not possible to obtain the desired accuracy only by ironing. There was an occasion. In addition, since there is no escape area for the material in the cross section orthogonal to the axis, in the case of a gear with a complicated cross-sectional shape, the meat flow complicates interference and the surface texture tends to become non-uniform, resulting in a decrease in surface roughness. become. Therefore, the quality tends to be uneven, which is one obstacle in reducing the manufacturing cost in terms of yield.

The present invention has been devised to eliminate such disadvantages of the prior art, and its main purpose is to improve the quality without increasing the manufacturing cost. It is to provide a die for tooth profile sizing.

[0007]

According to the present invention, such an object is to perform ironing on a tooth profile of an intermediate forming material obtained by roughly forming a gear tooth profile along the axial direction by forging. In a tooth profile sizing die with a finished tooth profile,
Set the tip circle diameter of the finishing tooth profile smaller than the tip circle diameter of the tooth profile of the intermediate forming material, and increase the bottom circle diameter of the finishing tooth profile compared to the root circle diameter of the tooth profile of the intermediate forming material. In addition to setting, the tooth thickness of the finishing tooth profile is set smaller than the corresponding dimension of the tooth profile of the intermediate forming material, and the dimensional difference in tooth thickness between the tooth profile of the intermediate forming material and the finishing tooth profile is calculated from the root. This is achieved by setting the taper gradually decreasing toward the end.

[0008]

[Advantage] By doing so, the ironing allowance gradually decreases from the root to the end of the tooth, so that the amount of compression of the surface tissue is optimized in accordance with the difference in the tooth thickness between the root and the tip. In addition, since the clearance on the tooth bottom side between the die and the intermediate forming material is large, the escape area of the material is secured at the tooth root part, so the direction of the material flow in the cross section orthogonal to the axis line. Is adjusted in one direction from the addendum to the root. In addition, by reducing the clearance on the tip side between the die and the intermediate forming material, the diameter accuracy of the tip circle can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

1 and 2 schematically show the main parts of a sizing device constructed according to the present invention. This sizing device includes a pressing punch 2 provided on a movable platen 1 of a press machine and a die 4 provided on a fixed platen 3 of the press machine.
And a knockout punch 5.

The pushing punch 2 is fixed to the movable platen 1 via a punch holder 6, and by driving the movable platen 1, it is displaced along a predetermined axis (up and down direction in this embodiment). It is supposed to do.

A finish tooth profile 7 is formed on the inner peripheral surface of the die 4 and is fixed to the stationary platen 3 via a die holder 8.

The knockout punch 5 has a guide ring 9 slidably engaged with the die 4 and the die holder 8, a knockout 10 axially slidably received in the guide ring 9, and a knockout 10. And a knockout pin 11 for projecting in the axial direction.

The upper end 9a of the guide ring 9 in FIG.
Is reduced in diameter, for example, a center hole 13 of an intermediate forming material 12 in which a gear tooth profile used for a pinion gear of a transmission is roughly processed.
It is adapted to be fitted in relatively tightly. Further, the upper end surface 10 a of the knockout 10 is in contact with the shoulder portion 13 a of the center hole 13 of the intermediate forming material 12.

A cushion member 14 made of urethane resin or the like is interposed between the guide ring 9 and the fixed platen 3, whereby the guide ring 9 is constantly repulsed upward in FIG. Being energized.

As shown in FIG. 3, on the inlet side of the die 4,
Substantially uniformly over the entire circumference of the opening of the finishing tooth profile 7,
A chamfer 20 that expands toward the opening end face side is provided. Then, as shown in FIG. 4, the tip circle diameter of the finished tooth profile 7 of the die 4 shown by the solid line is smaller than the tip circle diameter of the coarse tooth profile 12a of the intermediate forming material 12 shown by the imaginary line by d1. The diameter of the root circle of the finished tooth profile 7 is set to the coarse tooth profile 12
It is set to be larger by d2 than the diameter of the root circle of a. That is, when the intermediate forming material 12 is pushed into the die 4, the tooth crest 21 is squeezed by d1, but the tooth bottom 22 is rather squeezed with a gap c1 between the tooth bottom 21 and the finishing tooth profile 7.

Regarding the thickness of the tooth end portion, 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 are substantially equal, but the thickness of the tooth root part is the same. The dimensions are such that the coarse tooth profile 12a of the intermediate forming 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, regarding the ironing allowance of the tooth surface 23, as shown by the dimension d3 to d5 in FIG. 4, the tooth root side is larger, and the ironing allowance gradually decreases toward the tooth end, and the tooth end part is hardly squeezed. It is like this.

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

First, in a state in which the movable platen 1 with the pushing punch 2 is sufficiently raised, the intermediate forming material 1 having the rough tooth profile 12a whose outer contour has been adjusted in advance and which has been roughly processed.
The center hole 13 of 2 is fitted into the upper end portion 9a of the guide ring 9, and the rough tooth profile 12a of the intermediate forming material 12 is aligned with the finishing tooth profile 7 of the die 4. At this time, the lower end of the rough tooth profile 12a of the intermediate forming material 12 and the upper end of the finishing tooth profile 7 of the die 4 are slightly engaged with each other on the slope of the chamfer 20 or with a slight gap, as shown in FIG. Although it may be provided, at least the axial inner end surface 12b of the intermediate forming material 12 and the upper end surface 9b of the guide ring 9 should be in close contact with each other from the beginning.

Next, when the pushing punch 2 is lowered together with the movable platen 1, the lower surface 2a of the pushing punch 2 and the upper surface 12c of the intermediate forming material 12 come into contact with each other. At this time, since the intermediate forming material 12 is elastically floatingly supported in the axial direction via the guide ring 9, the intermediate forming material 12 is pushed by the reaction force of the cushion member 14 before being pushed into the die 4. The lower surface 2a of the punch and the upper end surface 12c of the material are in close contact with each other accurately. As a result, the squareness of the material upper end surface 12c with respect to the axis of the die 4 is correct (FIG. 1).

From this state, when the pressing 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 portion of the finishing tooth profile 7. It is pushed into the die 4 while being held between the pushing punch 2 and the guide ring 9 (FIG. 2). Therefore, the sliding axis of the intermediate forming material 12 is correctly held, and at the same time, the inner periphery of the center hole 13 is restricted by the upper end portion 9a of the guide ring 9, so that the tooth profile is prevented from being distorted inward. To be done.

When the intermediate forming material 12 is pushed in, the surface of the material is squeezed by the inner surface of the die 4.
Since the dimensional difference shown in FIG. 4 is provided between the tooth profile of No. 3 and the tooth profile of the finished tooth profile 7, the ironing allowance gradually decreases from the root to the end of the tooth. Therefore, the compressibility of the surface tissue is optimized in accordance with the difference in tooth thickness between the root portion and the end portion. In addition, since the clearance shown by d2 in FIG. 4 is provided between the tooth bottom surface 22 of the intermediate forming material 12 and the corresponding surface of the finished tooth profile 7, the escape area of the material is secured at the tooth bottom portion, The direction of material flow in the cross section orthogonal to the axis is adjusted in one direction from the addendum to the root. As a result, the directionality of the surface texture becomes constant and interference does not occur in the flow of the texture, so that stable improvement of surface roughness can be expected. It should be noted that in the root circle, an error in the negative direction does not actually cause harm, and the influence of the surface roughness can be ignored.

On the other hand, the relatively important tip circle diameter is the die 4
The tooth profile of the finished tooth profile 7 is the rough tooth profile 1 of the intermediate forming material 12.
A minus clearance is set with respect to the tooth tip surface of 2a, and the rough tooth profile 12a is squeezed by the finishing tooth profile 7, so that a predetermined accuracy can be obtained.

Further, although the meat is extruded in the axial direction as well, as shown in FIG. 5, the flange portion 24 formed as an unremoved portion at one axial end of the intermediate forming material 12 and the coarse tooth profile 12a. Since the chamfer 20 formed at the open end of the die 4 is sufficiently larger than the radius of the corner, when the intermediate molding material 12 is pushed into the die 4 to the full,
Excessive meat is absorbed by flowing into the void c2 generated in this portion.

When the movable platen 1 is raised together with the pressing punch 2 after the pressing is completed, the finished material 12 is released from the die 4 by the reaction force of the cushion member 14.
Then, the knockout pin 11 is pushed out by using a driving means (not shown), so that the material 12 is released from the guide ring 9 as a finished product.

[0026]

As described above, according to the present invention, by appropriately setting the contour of the finishing tooth profile according to the cross-sectional shape of the tooth profile of the intermediate forming material, the dimensional reduction rate of each part is optimized,
Moreover, since the meat flow direction is constant, the dimensional accuracy and the surface roughness of the tooth surface are improved. Therefore, there is a great effect in improving the quality stability and the yield.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a material is set in a tooth profile sizing device according to the present invention.

FIG. 2 is a cross-sectional view similar to FIG. 1 showing the completion of processing.

FIG. 3 is an enlarged perspective view partially showing an introduction portion of a finishing tooth profile.

FIG. 4 is an explanatory diagram showing a relationship between a rough tooth profile and a finished tooth profile.

FIG. 5 is an enlarged sectional view of an essential part showing the relationship between the intermediate forming material and the die at the start of ironing.

[Explanation of symbols]

 1 Movable plate 2 Pushing punch 2a Lower surface 3 Fixed plate 4 Die 5 Knockout punch 6 Punch holder 7 Finishing tooth profile 8 Die holder 9 Guide ring 9a Upper end 9b Upper end face 10 Knockout 10a Upper end face 11 Knockout pin 12 Intermediate forming material 12a Internal tooth 12b End surface 12c Upper surface 13 Center hole 13a Shoulder portion 14 Cushion member 20 Chamfer 21 Tooth tip surface 22 Tooth bottom surface 23 Tooth surface 24 Flange portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 64-71543 (JP, A) JP-A 54-130462 (JP, A) JP-A 64-71542 (JP, A) Actual development Sho-64- 42747 (JP, U)

Claims (1)

[Claims] 1. A tooth profile sizing die having a finishing tooth profile for ironing the gear tooth profile of an intermediate forming material obtained by roughly forming a gear tooth profile along the axial direction by forging, wherein the intermediate The tip circle diameter of the finishing tooth profile is set smaller than the tip circle diameter of the tooth profile of the forming material, and the root circle diameter of the finishing tooth profile is set to be smaller than the root circle diameter of the tooth profile of the intermediate forming material. With a large setting, the tooth thickness dimension of the finishing tooth profile is set smaller than the corresponding dimension of the tooth profile of the intermediate forming material, and the tooth thickness dimension of the tooth profile of the intermediate forming material and the finishing tooth profile. A tooth profile sizing die, characterized in that the difference is set to gradually decrease from the root to the end of the tooth.