JPS61249642A - Extrusion molding method for tooth profile - Google Patents

Abstract

PURPOSE:To form the tooth profiles of a gear, spline, etc. with low pressing force and high accuracy by using a die provided with a tooth profile forming part on the inside circumference and extrusion-molding the tooth profile on the outside circumference of a shaft stock while building up the surface layer part of the stock to the bottom side of the tooth profile forming part by means of the above-mentioned die. CONSTITUTION:The tooth profile forming part 4 of the die 1 is provided with a drawing part 4a having a prescribed drawing angle alpha and a relief part 4b. The large diameter part W1 of the shaft stock W0 is slightly smaller than the inside diameter of the guide part 3. On the other hand, the outside diameter D of the small-diameter part W2 is set at such a size at which the sectional area A1 positioned on the bottom surface of the tooth profile 11 to be formed and the sectional area A2 positioned on the tip side are made equal. The desired tooth profile 11 is formed on the outside circumference of the small-diameter part W2 by the forming part 4 when the stock W0 is pressed by a punch 12 in the die 1. The fomation of the tooth profiles of the gear, spline, etc. with the low pressing force and high accuracy is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for cold extrusion molding a tooth pattern of a spline, gear, etc. on the outer periphery of a shaft.

(Prior Art) Japanese Patent Publication No. 52-33583, for example, is known as a method for extruding tooth shapes such as splines and gears on the outer periphery of a shaft. Japanese Patent Publication No. 52-33593 uses a blank shaft with a suitably smaller diameter than the inner diameter of the die, and uses the die to punch out the grooves between the tooth portions for molding by cold extrusion, thereby forming a tooth pattern on the outer periphery of the blank shaft. It is.

(Problems to be Solved by the Invention) However, in this prior art, as shown in FIG. 8, the groove between the tooth molds is punched out by the tooth mold forming part (101), so the extrusion molding load is high. For example, when forming a long spline, the flow resistance of the material gradually increases, and there may be cases where the forming load exceeds the buckling load. Therefore, the drawing angle (α) of the tooth molding part (101) must be set relatively gently, and a guide part (102) must be provided to prevent the material from swelling outward. , it is difficult to mold the teeth of splines, gears, etc. up to the stepped part of the stepped shaft, and as shown in FIG.
The dimension (intersection) between the two must be long. Furthermore, since flow resistance increases during molding, it is particularly difficult to simultaneously mold tooth shapes at multiple locations on a multi-stage shaft, resulting in an unavoidable increase in the number of steps.

The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to reduce the molding load, to form tooth shapes with high precision, and to form tooth shapes at multiple locations on a multi-stage shaft. An object of the present invention is to provide an extrusion molding method that enables molding of a stepped portion of a stepped shaft at the same time.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention uses a shaft-like material on the outer circumferential surface of which a tooth pattern such as a gear or spline is formed, to have a cross-sectional area approximately equal to the cross-sectional area of the product to be formed. A mold formed with an outer diameter having a cross-sectional area and having a tooth molding part on the inner periphery is used to extrude and mold the tooth mold on the outer periphery of the material while raising the surface layer of the material to the bottom side of the tooth molding part. It is characterized by the following.

(Function) The outer diameter of the material is set to have a cross-sectional area that is approximately the same as the cross-sectional area of the product to be molded, and the surface layer of the material is molded while being raised to the bottom side of the tooth molding part, so the molding load is reduced. At the same time, it is possible to form a tooth pattern with high accuracy while reducing the amount of noise, it is possible to simultaneously form the tooth pattern at multiple locations on a multistage shaft, and the drawing angle is increased to form the tooth pattern up to the stepped portion of the stepped shaft. I can do it.

(Embodiment) A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of the material and mold during extrusion molding, FIG. 2 is a half-cut composite plane sectional view showing before and after tooth molding, and FIG. 3 is a longitudinal sectional view of the molded product.

In FIG. 1, (1) is a mold installed on the machine stand of a press mold device (not shown), and the mold (1) has a mold hole (2
), the upper part of the mold cavity (2) constitutes a material guide part (3), and the lower inner periphery of this guide part (3) has teeth having a tooth pattern as shown in FIG. A molded part (4) is provided in a protruding manner. A constricted part (4a) and a relief part (4c) are provided at the top and bottom of this tooth molded part (4), respectively, and the constricted part (4a)
has a predetermined aperture angle α. Also, this tooth molding part (4
) and the material guide portion (3) are connected by a horizontal step portion (5).

As shown in the figure, the stepped material (Wo) has a large diameter part (WO) at the upper end and a small diameter part (112) which is the workpiece part at the bottom. The mold (1) is brought into sliding contact with the guide part (3) of the mold (1) as shown in FIG.
Set inside.

The outer diameter of the large diameter part (wl) of the material (Wo) is the same as that of the mold (1).
is set slightly smaller than the inner diameter of the guide part (3),
On the other hand, the outer diameter (D) of the small diameter part (2) is the cross-sectional area (A) located on the tooth bottom side than the outer diameter (D) of the tooth mold (11) to be formed there, and the The cross-sectional area (A2) located at is set to be approximately equal to the cross-sectional area (A2).

After setting the material (Wo) in the mold (1), the material (-〇)
When the material (Wo) is pressed downward with the punch (12) in contact with the upper end surface, the material (Wo) moves downward, thereby forming a tooth-shaped molded portion (4) on the outer periphery of the small diameter portion (W2). A desired tooth shape (11) is formed. During this extrusion molding, the outer diameter (D) of the small diameter portion (W2) is molded into the tooth mold (11).
The cross section i (A+
) and the cross-sectional area (A2) located on the tooth tip side are set to be approximately equal, so as shown in Fig. 2, the small diameter part of the material (
The desired tooth shape (11 ) is formed. That is,
In Fig. 2, the material small diameter portion (112) is the tooth molding portion (4).
) The half of the tooth bottom part (11-1) that interferes with each tooth of the tooth molding part (4) flows from left and right into the tooth bottom space of the tooth molding part (4) as shown by the arrow in the same figure, and the tooth on the small diameter part (112) side of the material The tooth tip (11-2) of the mold (11) is configured, and in this case, the tooth mold (11) is an involute spline. In this way, the cross-sectional area of the small diameter part (-2) before and after the tooth molding is made almost the same, and the tooth bottom (4a) of the tooth molding part (4) in the surface layer of the material small diameter part (2)... Since the desired tooth shape (11) is formed by sideward heap forming, forming is possible with low pressing force, suppressing increase in flow resistance of the material (WO),
The axial compressive force of the material (Wo) can be reduced, the conventional guide part (102) can be made unnecessary, and the tooth molded part (4)
The aperture angle α can be set larger than that of the conventional one.

Since the guide part (102) is not necessary, the molded product (13) after extrusion molding is formed with a tapered part (14) whose axial length is shorter than that of the conventional one, as shown in FIG. Tooth pattern (11) up to stepped part (15) corresponding to horizontal part (5)
It becomes possible to mold.

Table 1 shows the number of teeth: 30, module l, standard pitch circle diameter: 30 m
m, product cross-sectional area 708.5 m When molding an involute spline of layer 2, the results of experiments conducted on various materials with different cross-sectional areas are shown.

Table 1 As is clear from Table 1, the product cross-sectional area is 708.5 mm.
When using a material with a diameter of 30 m and the same cross-sectional area as 2), the tooth profile can be formed with high precision and the forming load can be reduced.

Next, a second embodiment will be described with reference to FIGS. 4 to 7.

As shown in Fig. 4, the material (W2o) is manufactured by pressing, forging, etc. to form a multistage shaft, with a shaft section (21a) provided at one shaft end, followed by a large diameter shaft section (2To). In the illustrated example, there are multiple step shafts (21c) to (21c).
h) are formed, and these stepped shaft portions (21c) to (21h
) has a tapered shape with the diameter gradually decreasing toward the other shaft end. Figure 5 shows a shaft (2o) on which a tooth pattern (23) is formed on the outer peripheral surface by applying the method according to the present invention to a material (W2o).
0), and the tooth pattern (23) is the stepped shaft portion (21d).

(21F) and (21h) coaxially provided. Tooth shapes (23d) in these stepped shaft portions (21d), (21f), and (21h).

(23F) and (23h) are angle splines.

FIG. 6 is a composite cross-sectional view of the press mold device (24) according to the present invention, cut in half before and after the tooth molding process, with the left half cut-away view being before processing and the right half-cut view being after forming. The mold (24) is constructed by stacking six molds (25) to (30), each having a vertical thickness corresponding to the axial length of the stepped shaft portions (21c) to (21h). The molds (25) to (30) are arranged coaxially with the inner diameter holes (25a) to (30a) aligned. A guide mold (31) is provided at the top of the uppermost mold (25), and this guide mold (31) also has an inner diameter hole (
31a) are arranged coaxially. Mold (2
Among 5) to (30), mold (2B), (28),
(30) is a tooth molding die, and these dies (
2B).

(2B), (30) inner diameter hole (28a), (2
8a), the desired tooth shape (23) is placed on the top of (30a).
Tooth molding part (28b) corresponding to (28b)
, (30b) are formed to protrude inward and have a tooth shape.

The tip circle diameter of (30b) is the stepped shaft portion (21d), (21
F).

(21h) is equal to the root diameter of the tooth profile (23) to be formed, and the root diameter is equal to the tip diameter of the tooth profile (23).

Figure 7 shows the dice (2El), (28), (3
The material (W2+
This is a composite half-section plane cross-sectional view showing before and after θ is extruded and molded (@ mold (23)). The diameters (Dd), (Of), and (Dh) are the outer diameters (23d), (23f), and (23h) to be molded there.
The cross-sectional area (A3) located closer to the tooth bottom than Dd), (Or), and (oh) is set to be approximately equal to the cross-sectional area (A4) located closer to the tooth tip.

In Fig. 6, (32) is a sleeve punch that is moved up and down by a press means such as a ram, and (33) is a sleeve punch that is used to eject the shaft (20) on which the tooth pattern (23) is formed from the mold (24). It's a knockout punch.

Next, the tooth molding operation will be described. First, the material (%120) is inserted and set into the mold (24). The material (W2o) has a tapered stepped portion (
21i) and the tooth molded part (28b) of the die (2B), and the large diameter shaft part (21b) and the inner diameter hole (31a) of the guide mold (31) are aligned. When the sleeve punch (32) is lowered, the shaft (21a) is inserted into the punch (32), a press load is applied to the upper shoulder of the large diameter shaft (21b), and the shaft (21a) is inserted into the sleeve. The punch (32) also has a large diameter shaft (21b) with a guide type (3
1), the step shaft portion (21d) is pressed down while being restrained, and first, the stepped shaft portion (21d) is plastically deformed by the tooth molding portion (213b), and tooth molding is started. Material (12o)
When the downward extrusion stroke reaches a predetermined value, the tooth molding part (
30b) begins tooth molding of the stepped shaft portion (21h),
Next, the tooth molding part (28b) begins to mold the corrugated shaft part (21f), and when the material ('$120) reaches its lowering limit, the die (2B) is released.

(28), (30) tooth molded parts (28b), (28b
) (30b), each stage shaft part (21d), (21
F>, (21h) desired tooth shape (23d), (2
3f) and (23h) are molded.

Therefore, the material (I
A plurality of tooth molds (23)... can be simultaneously molded on the tooth mold (23), and these tooth molds (23) are provided coaxially.
23)... are coaxially arranged molds (25) to (30), and tooth molding parts (28b), (28b), (3
0b) has an effect of correcting shaft center and tooth line errors, so it has excellent concentricity accuracy and tooth line accuracy.

When molding the tooth pattern (23), the die (2
13), (28), (30) 7) Tooth molding part (28b
), (28b), (30b), the step shaft part (21
d), (21F), and (21h) are subjected to compressive plastic deformation in the inner radial direction and are first formed into tooth shapes (23d) and (23h).
f).

(23h) bottom side (23d-1), (23f-1),
(23h-1) is molded, and the excess material generated by plastic deformation on the bottom side of the tooth as the material (W2o) is extruded becomes the tooth molded part (
28b), (28b).

It escapes to the valley of (30b), and this meat is on the tooth tip side (23d-2)
, (23f-2) and (23h-2) to form the tip of the tooth mold (23).

Step shaft portions (21d), (21f) before and after tooth molding,
By making the cross-sectional area of (21h) almost the same, processing the outer surface of the shaft and raising the meat on the tooth bottom side toward the tooth tip side, the tooth shape (
23), the amount of processing is small, so the material (W2
By reducing the extrusion molding load applied to o), the tooth shape can be molded with high precision, suppressing the increase in flow resistance of the material (W2o), and molding multiple tooth shapes (23)... at the same time as described above. becomes possible.

Further, according to the present invention, even when a tooth pattern is formed on a hollow shaft, deformation and twisting due to buckling do not occur, so the tooth pattern can be formed with high precision, and it can also contribute to reducing the weight of the product. Also,
It is obvious that the present invention can also be applied to internal teeth.

(Effects of the Invention) As is clear from the above description, according to the present invention, in a molding method of cold extruding tooth shapes such as splines and gears on the outer periphery of a shaft, the molding load is reduced and the tooth shapes are formed with high precision. It is possible to simultaneously mold tooth shapes at multiple locations on a multi-stage shaft, and it is also possible to mold a stepped portion mold for a single-stage shaft.

[Brief explanation of the drawing]

Figure 1 is a vertical side view of the material and mold during extrusion molding, Figure 2 is a half-cut composite plane cross-sectional view showing before and after tooth molding, Figure 3 is a vertical side view of the molded product, and Figure 4 is a side view of the molded product. Figure 5 is a diagram of the multi-stage shaft with the tooth mold formed, Figure 6 is a side sectional view of the mold device cut in half before and after tooth mold forming, and Figure 7 is the tooth mold formed. FIG. 8 is a longitudinal sectional side view of a conventional device, and FIG. 9 is a longitudinal sectional side view of a conventional molded product. In addition, (1) and (24) in the drawing are molds, (4) and (28
b), (28b). (3ob) is a tooth mold molding part, (11) and (23) are tooth molds,
(Wo). (W2o) is the material. Procedural amendment (voluntary) June 11, 1985

Claims (2)

[Claims] (1) A shaft-shaped material on which tooth patterns such as gears and splines are formed on the outer circumferential surface is formed with an outer diameter that has approximately the same cross-sectional area as the cross-sectional area of the product to be molded, and a tooth pattern molded part is formed on the inner periphery. A tooth mold extrusion molding method, characterized in that a tooth mold is extruded onto the outer periphery of the material while the surface layer of the material is raised on the bottom side of the tooth molded part using a mold comprising: (2) A large-diameter guide portion corresponding to the outer diameter of the material is formed on the material insertion side of the tooth molding portion of the mold, and the guide portion and the tooth molding portion are connected to each other via a horizontal step. The tooth type extrusion molding method according to claim 1, wherein the teeth are connected as follows.