JPH01162535A - Method for forging toothed shaft - Google Patents

Abstract

PURPOSE:To fill up sufficiently a material in a die hole and to improve the accuracy of the tooth part shape by press-fitting the work shaft part of the outer diameter equal to the large diameter side part of a step part into the die hole corresponding to the shape of the step part and tooth part and execut ing forging by its extruding in the case of forging the tooth part to the small diameter side part of the step part. CONSTITUTION:Each part of a bar-like work 1 forming a step part in the shape close to step parts 1e, 1i is subjected to upsetting at a 1st stage to form in each step part 1e, 1i and each shaft part 1c, 1d, 1g, 1h and also in the truncated conical shaped part of the preforming shape of a large diameter part 1f. At a 2nd stage the truncated conical shaped part of a work 1 is further subjected to upsetting to form in the large diameter part if and also the step part 1a from the lower end part if the shaft part 1d of the work 1 to the lower part shaft end and the shape of the part becoming a spline part 1b are made in the circular columnar shape of the same diameter as that of the shaft part 1d. At a 3rd stage, the part 1j becoming the step part 1a and spline part 1b is press-fitted into the die hole 25a of a die 25 and forged to the step part 1a and spline part 1b by forward free extrusion forging.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for forging a toothed shaft that is suitable for forging a toothed shaft that has teeth on the small diameter side portion of the stepped portion. It is.

(Prior Art) In the case of forging a shaft having teeth on the small diameter side portion of the stepped portion, for example, a workpiece 1 to be used as an input shaft of an automatic transmission of an automobile is cold forged as shown in Fig. 3. In some cases, the workpiece 1 has a stepped portion 1a at one end thereof, and a spline portion 1b serving as a tooth portion, which is drive-coupled to a torque converter, on the smaller diameter side of the stepped portion 1a.

When forging the spline portion 1b of such work 1,
Conventionally, as shown in the left half of FIG. 4, a stepped portion 1a and a shaft portion 1 having an outer diameter substantially equal to the spline portion 1b are formed on the workpiece 1, and the workpiece 1 is , is press-fitted into the die hole a of the die 2, which has an inner surface shape corresponding to the shapes of the stepped portion 1a and the spline portion 1b, and the shaft portion 1k is inserted into the spline portion as shown in the left half of FIG. 1b, a so-called trap extrusion method was used.

(Problems to be Solved by the Invention) However, in this conventional method, the material is not sufficiently filled in the die hole near the tooth tip of the spline portion 1b, and as shown by the solid line in FIG. The corners were rounder than the regular tooth shape shown by the medium imaginary line, and the outer diameter was narrowed near the tip of the spline part 1b as shown in Figures 6(a) and (b). There was a problem in that the shape was changed. In order to solve this problem, when an attempt was made to press the stepped portion 1a against the corresponding portion of the die hole 2a to promote further flow of the material, there was a problem in that the pressing pressure became too high.

The present invention provides a method that advantageously solves the above-mentioned problems.

(Means for Solving the Problems) The method for forging a toothed shaft of the present invention includes the following steps: When forging a toothed shaft having teeth on the small diameter side portion of the stepped portion, substantially the large diameter side portion of the stepped portion is forged. □A workpiece shaft with the same outer diameter is press-fitted into a die hole with an inner surface shape corresponding to the shape of the step and teeth, and the workpiece shaft is formed into the step and teeth by extrusion forging. It is characterized by

(Function) In this method, the outer diameter of the workpiece shaft to be press-fitted into the die hole is substantially equal to the large diameter side portion of the stepped portion, and the workpiece shaft is press-fitted into the die hole to form the stepped portion. Since the die hole portion corresponding to the shape of the tooth portion is formed with a sufficient amount of material, the shape accuracy of the tooth portion is sufficiently high. .

In addition, in this method, the workpiece shaft is filled into the die hole corresponding to the tooth shape from the beginning of press-fitting, so
Press pressure does not become too high.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a toothed shaft to which the forging method of the present invention is applied.
It is a vertical cross-sectional view showing the main parts of a forging die for three steps for cold forging the workpiece 1 which becomes the input shaft, and in the figure, 3 indicates a die plate, and 4 indicates a die holder fixed to the die plate. show.

Here, three through holes 3a and 4a are formed in each of the die plate 3 and the die holder 4, and are aligned with each other.
A hard plate 5, a bottle case 6, and a die case 7 each having a through hole in the center and having a substantially cylindrical shape are successively fitted into the through holes 3a, 4a, respectively. Then, while the outer peripheral step of the hard plate 5 is engaged with the step of the die plate through hole 3a, the through holes of the three fixing plates 8 are respectively fitted into the die case 7.
The hard plate 5, the bottle case 6, and the die case 7 are attached to the die by engaging the outer circumferential step part of the hard plate 5, the bottle case 6, and the die case 7 with the step part IC of the through hole of the fixing plate 8, and fixing the fixing plate 8 to the die holder 4, respectively. It is fixed to the plate 3 and die holder 4.

In each through hole of each hard plate 5, there is a knockout rod 9 whose lower part projects downwardly therefrom, and in each through hole of each pin case 60 there is a knockout bottle 10, 11 whose tip part projects upwardly therefrom. 12, and in the through hole of each die case 7 are dies 13. each formed by combining a plurality of ring-shaped parts for three-step molding. 14.
15 are arranged respectively.

Here, the knockout rod 9 and the knockout bottles 1G, 11.12 are held in their respective through holes so as to be able to move up from the lower limit position shown in the figure and down to that position, respectively. 13, 14.15
are fixed in the die case 7 by engagement of their upper ends with the stepped portions of the through holes of the die case 7.

In addition, the knockout bins 11 and 12 have a convex portion on the tip surface for forming a center hole on the lower shaft end surface in the workpiece 10, and the die 13 has a third
The die hole 13a has an inner peripheral surface shape corresponding to the shape of the shaft parts 1c, ld and step part 1e of the workpiece 1 shown in the figure, and the die 14 further has a shape of the large diameter part 1f of the workpiece l. The die 15 has a die hole 15a with an inner peripheral surface shape corresponding to the shape of the shaft portions 1c, ld, steps 11a, le, and spline portion 1b of the work l. are doing.

On the other hand, reference numeral 16 in the figure indicates a punch holder fixed to a punch plate (not shown).
Three through holes 16a are formed at positions that can be aligned with a.

Here, a hard plate (not shown), a pin case 17, and a punch case 18 each having a through hole in the center and having a substantially cylindrical shape are sequentially fitted into the through holes 16a, and the hard plate The outer peripheral stepped portions are engaged with the stepped portions of the through holes of the punch plate, and the through holes of three fixing rings 19 are respectively fitted into the punch case 18, and the outer peripheral male threaded portions of these fixing rings 19 are fitted into the punch holder 16. These hard plates are tightened to the female screw portion provided at the end of the through hole 16a.
The pin case 17 and punch case 18 are fixed to the punch plate and punch holder 16.

Furthermore, knockout rods (not shown) are placed in the through holes of each of the hard plates (not shown), knockout pins 20, 21, and 22 whose tips protrude downwards are placed in the through holes of each pin case 170, and each In the through hole of the punch case 18, there are punches 23, 24, 2, each made of a combination of a plurality of ring-shaped parts, for three-step molding.
5 respectively. Here, the knockout rod and knockout pin 20.21.22 are respectively:
The knockout pins are held in each through hole so that they can be moved downward from the upper limit position shown in the figure and upwardly moved to that position, while the punches 23, 24, 25
are fixed within the punch case 18 by engagement of their lower ends with the stepped portion of the through hole of the punch case 18.

Further, in the figure of the workpiece 1, the knockout pins 21 and 22 have a convex portion at the tip for forming a center hole on the upper shaft end surface, and the punch 23 has a third
The inner peripheral surface shape corresponds to the shape of the shaft parts 1g, lh and step part 11 of the workpiece 1 shown in the figure, and for preforming of the swaging molding with the die 14, which uses the rod-shaped workpiece before forming as the large diameter part 1f. A punch hole 23 having a truncated conical inner peripheral surface shape.
a, and the punches 24 and 25 have shaft portions 1g, lh
and punch holes 24a and 25a having an inner peripheral surface shape corresponding to the shape of the step portion 1i.

The lower mold 26 has the dies 13 to 15 assembled to the die plate 3 as described above, and the punches 23 to the punch plate.
The upper die 27 formed by assembling the punches 25 to 25 is attached to a bolster 28 of a press machine and a slider (not shown), respectively, with the axes of the punch and die aligned in the vertical direction. Here, each knockout rod 9 of the lower die 26 protruding downward from the die plate 3 is inserted into the knockout hole 28a of the bolster 28, and the knockout rod 9 is inserted into the knockout cam mechanism (not shown) provided below the bolster 28. Enables contact with the lifting rod.

With this, the knockout rod of the upper die 27 is
It is located at a position where it can come into contact with a piston rod of an air cylinder (not shown) provided above the slide.

In this example method using a forging die with such a configuration,
First, punch 23 and die 1 located at the left end in the figure
In the first step using the die 13, a stepped portion 1e,
Each part of the rod-shaped workpiece 1 with a stepped part in a shape similar to li is upset forged to form each stepped part 1e, li and each shaft part 1c, ld, Ig, lh, and the large diameter part 1f is prepared as a spare. Molded into a truncated conical shape.

At this time, the axial dimension of the workpiece 1 is also specified by the knockout pins 10, 20 coming into contact with the hard plate 5 and the hard plate (not shown), respectively.

Next, in a second process using the punch 24 and die 14 located in the center in the figure, the truncated conical part of the workpiece 1 formed in the first process is further upset forged to have a large diameter. At the same time, a center hole is formed by a convex tip of the knockout pin 11.21 whose lower limit position and upper limit position are specified by contact with the hard plate 5 and the hard plate (not shown), respectively. In this step, the shape of the step portion 1a and the spline portion 1b from the lower end of the shaft portion 1d of the workpiece 1 to the lower shaft end is made into a cylindrical shape having the same outer diameter as the shaft portion 1d.

Thereafter, in a third step using the punch 25 and die 15 located at the right end in the figure, the portion IJ that will become the step portion 1a and the spline portion 1b shown in the left half of FIG. 25 into the die hole 25a, and forged into the step portion 1a and the spline portion 1b by so-called open extrusion forging, that is, in this example, front free extrusion forging. Further, in this process, the knockout pins 12 and 22, whose lower limit positions and upper limit positions are specified by contact with the hard plate 5 and the hard plate (not shown), respectively, are moved in the axial direction of the material of the workpiece 1 by their tip surfaces. The axial direction dimension of the workpiece 1 is set to a predetermined dimension by regulating the flow to the workpiece 1.

These three forging steps are performed by raising and lowering the upper die 27 between the upper limit position (not shown) and the lower limit position shown in FIG. 1 based on the lowering and raising of the slide of the press machine. The workpiece 1 in each subsequent process is lowered by the knockout pins 20 to 22 of the upper die 27 based on the operation of the air cylinder above the slide, and knocked out of the lower die 26 based on the operation of the cam mechanism below the slide. pin 10
The punches and dies are separated from each other by the upward movement of 12, and then transferred to the next process by a conveying device (not shown), such as a robot.
Then, it is transported outside the mold.

Through the three steps described above, the shaft portion 1 shown in FIG.
c, ld, Ig, lh, stepped portion 1a, le,
li, a large diameter portion 1f, and a spline portion 1b on the small diameter side of the step portion 1a can be formed, and according to this method, the die hole 5 can be formed in the second step and the next step.
Since the shaft part IJ to be press-fitted into the spline part a is formed so that its outer diameter is equal to the outer diameter of the shaft part 1d, in the third step, a sufficient amount of material is inserted into the die hole corresponding to the shape of the spline part. The shape accuracy of the spline portion 1b can be sufficiently improved, and furthermore, since the shaft portion 1j is filled into the spline-shaped portion from the beginning of press-fitting into the die hole portion corresponding to the spline shape, Forging can be performed without excessively increasing press pressure.

Furthermore, according to the above example, the step portion 1a and the spline portion 1b
Since both are molded simultaneously in one step, the number of molded parts in the previous step can be reduced, and the number of steps can be reduced.

Although the above has been explained based on the illustrated example, the present invention is not limited to the above-mentioned example. For example, at an intermediate position of the shaft,
The invention can also be applied to the case where teeth are formed in the small diameter side portion of the step, and can be applied not only to the spline of the above example but also to the forging of gears in which the teeth and the shaft are integral.

(Effects of the Invention) Thus, according to the method of the present invention, it is possible to fill the die hole portion corresponding to the shape of the tooth with a sufficient amount of material, and the shape accuracy of the tooth can be sufficiently increased, and moreover, the press pressure can be reduced. Excessive rise can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view illustrating the main parts of a forging die to which the toothed shaft forging method of the present invention is applied, and FIG. 2 is a cross-sectional view showing the state of forming a workpiece in the third step of the forging die. Figure 3 is a front view showing an example of a workpiece, Figure 4 is a cross-sectional view showing a conventional forging method, Figure 5 is a cross-sectional view of a tooth formed by the above-mentioned conventional method, Figure 6 (a), ( b) is a front view and a side view of a tooth portion formed by the above conventional method. 1... Workpiece 1a... Stepped portion 1b...
Spline portion 13-15...Die 13a-15
a...Die hole 23-25...Punch 26...
Lower mold 27... Upper mold patent applicant: Nissan Motor Co., Ltd. agent patent attorney Hidetoshi Sugimura Patent attorney Oki Sugimura Figure 3

Claims (1)

[Claims] 1. When forging a toothed shaft having teeth on the small diameter side portion of the stepped portion, a workpiece shaft portion having an outer diameter substantially equal to the large diameter side portion of the stepped portion is A method for forging a toothed shaft, characterized in that the workpiece shaft is press-fitted into a die hole having an inner surface shape corresponding to the shape of the stepped part and the toothed part, and the workpiece shaft part is formed into the step part and the toothed part by extrusion forging.