JPS6342528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a gear material 107b with dowels, in which several protrusions (hereinafter referred to as dowels) are formed at eccentric positions on the end surface of the material 107a by cold forging, and in particular, as shown in FIG. , as shown in Figure 10, dowel 1
08 in the forward direction of the punch and an annular protrusion 109 made of surplus material in the backward direction of the punch.

In the conventional manufacturing method of gear material with dowels by forging, for example, as shown in FIG. The material 7a is forged using a punch 4 provided with several concave arrow portions 6 that form dowels 8 in series on one side, and then the annular protrusion 9 of the forged gear material 7b with dowels (FIG. 2) is turned on a lathe. Accordingly, the semi-finished product 7c shown in FIG. 3 was cut out.

However, when using this method, since the annular projection 9 is removed after forging by holding the outer periphery in its mouth, there is a drawback that the misalignment of the dies 1, 2 and punch 4 during forging directly appears as eccentricity of the dowel position of the product. . In general, the misalignment between the die and punch is
Large at 0.075-0.15mm.

Further, in this method, since the contact point between the recessed part 6 and the notch part 5 on the punch tip side forms a plurality of corners, there is a drawback that the punch tip side is easily damaged.

In this method, the outer diameter side shape of the dowel 8 that is in contact with the annular protrusion 9 is limited to a rounded shape that is concentric with the outer periphery of the product. It has the disadvantage of not being able to form dowel shapes, and cannot meet the demands for a variety of dowel shapes.

To meet the requirements for such various dowel shapes, hot forging, for example, a horizontal burr forging method as shown in FIG. 4 has been applied. However, in general, with hot forging, not only the strength of the dowel 18 is inferior due to the roughness and the accuracy is low due to the influence of heat, but also the opening periphery 16a (Fig. 5) of the recessed hole 15 for dowel forming is due to the influence of heat. There was a drawback that the peripheral edge 16b of the opening shown in FIG. 6 wore out prematurely.

Therefore, the present invention was made to solve the above-mentioned drawbacks, and it makes it possible to form dowels with high positional accuracy with respect to the outer periphery, and also allows dowels to be formed in a free shape. The purpose is to provide a forging method with less. In addition, in order to promote the flow of the material into the recessed hole located at an eccentric position and to prevent the occurrence of defects (sink marks) on the outer periphery corresponding to the dowel position, the dowels are mainly placed on the surface surface of the dowel molding of the material and on the surface surface of the outer periphery of the material. The purpose is to cause material surface flow toward the outer periphery of the back surface.

The feature of the present invention is that a material with an outer diameter that is approximately the same as the large diameter part of the die engraving space is inserted into the lower mold, a recessed hole for dowel forming is provided at the bottom of the inner circumference of the die, and the dowel is punched forward by cold forging. By making the dowel protrude in the direction of the punch and making the excess meat protrude in an annular shape in the direction of the punch retreat, the dowel position can be finished with die precision (approximately 0.005 mm).
Further, it is possible to freely shape the dowel shape, prevent breakage of the punch, and prevent wear of the opening periphery of the die recessed hole.

The configuration of an embodiment of the present invention will be explained below with reference to the drawings.

FIG. 7 shows a cross section of the main part of the forging device, with the left half showing the state in which the material 107a is attached, and the right half showing the state in which the punch 104 has descended into the lower mold 100. 8 to 12 show changes in shape at each processing stage from the raw material 107a to the product 107d.

In FIG. 7, the lower die 100 includes a tightening ring 10
3 and thereby dies 101 and 102 fixed on the same axis as a punch 104, and fixed on the upper surface of a machine table (not shown) of a forging device. In the center engraving spaces of the dies 101 and 102, there are a large diameter part 113 that opens upward and several recessed holes 1 for forming dowels facing downward in the bottom part 114 of the large diameter part.
05 is perforated.

The large diameter portion 113 of the die is formed so that its axial length is longer than the axial length of the material 107a as shown on the left side of FIG. 7, and the diameter of the inner circumference is slightly larger than the diameter of the material 107a. There is.

The bottom of the recessed hole 105 communicates with the relief hole 111 via a chamfered portion, and further connects to the air vent hole 112 below.
is familiar with

Further, the punch 104 is connected to a ram (not shown) of a forging device and is mounted so as to be movable back and forth so as to face the engraving space of the lower die 100.

The diameter D ₁ of the outer periphery 116 on the tip side of the punch 104 is
It is formed smaller than the inner diameter D ₂ of the die large diameter portion 113 by a dimension of 2L. In this example, each dimension is as follows: Material: (diameter) 35 mm...Material steel.

_D1 : 32.6mm. _D2 : 35.1mm.

L: 1.2-1.35mm.

Therefore, when the punch 104 enters the die 101, there is an annular flow between the outer periphery 116 of the punch tip side and the inner periphery of the large diameter portion 113 of the die, which allows excess material to escape and provides smooth flow to the material. Gap 1
15 is formed.

Therefore, as shown on the left side of Fig. 7, the material 107a
is inserted into the large diameter part 113 of the die, and then the seventh
As shown on the right side of the figure, a punch 10 is placed inside the die 101.
4 enters, the flow of surplus material flowing into the flow gap induces a surface flow of the material toward the outer edge of the back surface opposite to the dowel on the dowel-formed surface layer and the outer peripheral surface layer of the material, and as a result, the material flows easily into the concave hole 105. Inflow.

When an appropriate flow gap 115 is provided in this manner, the surface pressure applied to the mold due to the entry of the punch 104 is low and the material flows smoothly, resulting in an extremely long mold life. In this example, the punch life is
There are 10,000 to 15,000 pieces, and the dies 101, 102 and the peripheral edge 106 of the recessed hole opening have little wear, and the dies hardly require replacement.

Moreover, since the punch 104 has a simple shape, it is easy to manufacture and can be manufactured at low cost, and the centering of the die and punch does not require much accuracy for reasons explained later.
Punch replacement can be done in a short time and productivity is good.
In this regard, in the conventional forging method shown in Fig. 1, the shape of the tip of the punch is complicated, and the life of the punch is as low as 4,000 to 6,000 pieces due to cracks that occur near the contact point between the concave part 6 and the notch part 5. Depending on variations in the heat treatment of the dies, the punch may break after 300 to 500 dies. Moreover, since the punch shape is complicated, the punch 4 is troublesome to manufacture and the manufacturing cost is high, and each time the punch 4 is replaced, it is necessary to accurately center the die and the punch over a long period of time, resulting in extremely low productivity.

In addition, since the above-mentioned forming according to the present invention is performed cold, the opening periphery 106 of the recessed hole 105 is not affected by heat and wear is not accelerated, and the recessed hole 1
The dowel 108 protruding from 05 is smooth and has high strength.

This pushing of the material into the die engraving space by lowering the punch forms a dowel 8 in the forward direction of the punch with reference to the inner circumferential wall of the large diameter portion 113 of the die, resulting in misalignment between the die and the punch. Highly accurate No. 9 design that has no effect on the product dowel position
Gear material 10 with dowels as shown in Fig. 10
7b can be obtained.

This gear material 107b with dowels is then cut with an annular protrusion 109 using a lathe or the like, and has a shaft hole 11 in the center.
7 to obtain a semi-finished product 107c as shown in FIG. At this time, since the dowel 108 protrudes in the opposite direction to the annular projection 109, there is no change in shape due to cutting and removal of the annular projection 109.

The semi-finished product shown in FIG. 11 is then finished, for example, with a gear formed on its outer periphery, such as a transmission gear with a dog clutch as shown in FIG. 12.

Next, regarding another embodiment, FIGS. 13 and 1
This will be explained using Figure 4. The symbols in the figure are indicated by adding 100 to the locations corresponding to the symbols of the embodiment in FIG.

In this embodiment, in order to improve the material yield, the material 207 is provided with a prepared shaft hole 21 as shown in FIG.
7a and then its preformed material 207a
As shown in Fig. 14, the dowel 2 is
08, the annular protrusion 209 is made to protrude in the backward direction of the punch, and the outer periphery is held in the mouth to cut the annular protrusion 209 and the shaft hole.
A semi-finished product 107c as shown in FIG. 1 is obtained.

As described above, in the production of gear materials with dowels, the present invention promotes the flow of the material into the recessed hole located at the eccentric position and prevents defects caused by the flow of the material.
A material with an outer diameter that is approximately the same as the large diameter part of the die engraving space is inserted into the lower die, and a cooling process is performed that causes surface flow of the material mainly on the dowel forming surface layer of the material and the outer peripheral surface surface of the material toward the outer peripheral edge of the back surface opposite to the dowel. Since it is a machining method, there are no defects (sink marks) on the outer periphery of the dowel position, and not only can the dowel shape be formed freely, but also the finish accuracy of the fixed mold is maintained, so the dowel position deviation is small and the finish is extremely high precision. In addition, the flow of the material is smooth due to the flow of excess material, and the surface pressure applied to the mold is low.The punch has no complicated corners, so the mold strength is high, and since it is cold-worked, the periphery of the recessed hole opening can be reduced. This has the effect of extremely long mold life, such as less wear and tear.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional cold forging method. FIG. 2 is a perspective view of the molded product. Figure 3 shows the semi-finished product. FIG. 4 is an explanatory diagram of a conventional hot forging method. FIG. 5 is an enlarged explanatory view of the recessed hole portion. FIG. 6 is an enlarged explanatory diagram of the wear state of the recessed hole portion. FIG. 7 is an explanatory diagram of an embodiment of the cold forging method according to the present invention. Figures 8 and 9 are perspective views of the material and molded product. FIG. 10 is a perspective view of the molded product seen from the opposite side in the axial direction from FIG. 9. 11th
The figure and FIG. 12 are perspective views of a semi-finished product and a finished product. FIGS. 13 and 14 show other embodiments of the present invention, and are explanatory diagrams of the preforming process and the dowel forming process. (Explanation of symbols), 100...Lower mold. 101,1
02...Dice. 103...Tightening ring. 104
...Ponchi. 105...Concave hole. 107a...Material. 107b...Gear material with dowels. 108...
Dowel. 109...Annular process. 110... Knock out. 113...Large diameter section. 114...Bottom. 11
5...Flow gap. 116...(Punch) Outer circumference on the tip side.

Claims (1)

[Claims] 1. The axial length of the large diameter portion 113 of the die engraving space is made longer than the axial length of the material 107a, and several recessed holes 105 for dowel molding are formed at eccentric positions on the bottom 114 of the large diameter portion 113. The material 107a having an outer diameter approximately equal to the inner diameter D ₂ of the large diameter portion 113 is inserted into the lower mold 100, and then there is an excess between the tip side outer periphery 116 and the inner periphery of the large diameter portion 113 of the lower mold 100. A punch 104 of a size that forms a flow gap 115 that allows the escape of the material is press-fitted into the die 101, and the material surface flow is mainly applied to the dowel-forming surface surface of the material 107a and the outer peripheral surface surface of the material 107a toward the outer edge of the back surface of the material. A method for manufacturing a gear material with dowels by cold forging, characterized in that a dowel 108 is formed in the forward direction of the punch 104 and an annular protrusion 109 made of surplus material is formed in the backward direction of the punch 104.