JPS63273538A - Metallic die for forming spline shaft - Google Patents

Abstract

PURPOSE:To reduce a production cost by forming a recessed part on a large diameter part and tooth face at the inlet port of the land of a forging die. CONSTITUTION:A recessed part 2b and projecting part 2c are formed in the specified dimension for a large diameter part and tooth face on the land 2a of the extruding die 1 of a spline shaft. A work 5 is insertion into the die 1 together with a mandrel 4 to execute pressurizing by a punch 3. In this case, the material at the tip 5a of the work 5 is first moved to the recessed part 2b to cause a shear droop. With the descent of the punch 3 the outer periphery in correct dimension is formed by the projecting part 2c of the land on the work 5. Since the dimension of the land projecting part 2c is formed smaller than that of a shear droop generating part the roll over caused at the land recessed part 2b is eliminated. Due to the shear droop generation being prevented accordingly the correction work of the shear droop part is made unnecessary and the production cost of a product is reduced.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a forging mold for spline shafts or gear shafts, and is used for forming spline shafts or gear shafts for automobiles and other applications. It is a thing□.

(Prior Art) As shown in FIG. 8, in the prior art related to the present invention, the land portion of a mold 12 having a spline 11 has a simple linear shape with a constant inner diameter.

(Problems to be Solved by the Invention) However, as shown in the enlarged view (c) of FIG. There is a problem in that sag 14a and 15a occur on the large diameter portion of the spline and the tooth surface.

When a rotating shaft spline used in an automobile transmission is manufactured using conventional technology, the extrusion tip has a diameter of about 0.4 am.
Since a sag of about 0.2 mm occurs at the rear end, correction processing such as cutting and cold processing is required in order to use it as a product, which increases manufacturing costs.

The technical object of the present invention is to provide a forging die for spline shafts or gear shafts that does not cause sagging at the extrusion tip and rear ends of manufactured products. .

[Structure of the invention] □ (Means for solving the problem) The technical means taken to solve the above technical problem are as follows. In other words, in a forging die for extruding a spline shaft or gear shaft on the outer periphery of a solid or hollow cylindrical material, a forging for forming a spline or gear shaft is provided, in which a recess is provided in the large diameter portion of the land portion and the tooth surface. It is a mold.

(Operation) The technical means operates as follows. In other words, if a recess is provided above the land of the forging die and the workpieces inserted into the mandrel are pressurized sequentially from above, the material flowing through the spline will be filled above the land. In the tooth surface portion, sag occurs due to the force acting toward the center due to the molding of the small diameter portion. As the molding progresses further, the land portion of a predetermined size (smaller than the size of the sag generation portion) is molded to the final size and extruded downward. In this molding, the amount of molding is very small, and since the small diameter part has already been molded, no force is applied toward the center, so no sagging occurs on the surface of the front and rear ends of the workpiece. It is possible to mold spline shafts or gear shafts with precise dimensions.

(Example) Examples will be described below.

In FIGS. 1 to 3, numeral 1 is an extrusion mold for a spline shaft, and numeral 2 is an uneven spline having an inner hole.

2a is a land portion, and a concave portion 2b and a convex portion 2C having a predetermined size are formed in the large diameter portion and the tooth surface, and 3 is a relief portion for the spline.

To explain the function of the mold, see Figures 4 to 7.
In the figure, 3 is a punch, 4 is a mandrel, and 5 is a workpiece for forming a spline on the outer peripheral surface.

Insert workpiece 5 together with mandrel 4 into mold 1 and punch 3
When pressure is applied at Due to the force acting toward the center as the part is formed, sagging 14a occurs (FIG. 4).

When the punch 3 is further lowered, the workpiece 5 has an outer periphery of the correct size due to the convex portion 2c of the land. Here, the dimensions of the land portion 2c are 0.1 to 0.2 larger than the dimensions of the sagging portion.
Since fi is set small, the sag that occurs at the land portion 2b is eliminated.

Furthermore, since the amount of molding in the land 2C is very small and the small diameter portion has already been molded and no force is applied toward the center, sag will not occur again (FIG. 5).

゛ Next, the punch 3 is raised, a new work 6 is inserted, and the work 6 is pressurized by the punch 3, so that the rear end of the work 5 sag at the upper part 2b of the land 2a as shown in FIG. 15a is generated, but when the workpiece 6 is further lowered by the punch 3, it is formed into the correct size by the convex portion 2C of the land portion and is pushed out below the mold 1 (FIG. 6).

As a result, as shown in FIGS. 7(a) and 7(b), there is no sag at all on the front end 8a and rear end 8b of the surface 8 of the workpiece 5, and the spline shaft 5 with precise dimensions is formed.

7 is a spline.

〔Effect of the invention〕

The present invention has the following effects. In other words, when molding with conventional molds, sagging occurs on the product surface, and double punching is performed to correct the dimensions of the sagging, but with the method of the present invention, no sagging occurs at all. In addition, there is no need to remove the sagging portion, resulting in a very high yield, and there is no need for double punching, resulting in a significant cost reduction.

[Brief explanation of drawings]

Figure 1 is a sectional view of this embodiment, Figure 2 is an enlarged view of the main part of Figure 1, Figure 3 is a sectional view taken along line A-A in Figure 2, and Figures 4 to 6 are processing process diagrams. FIG. 4 shows the situation immediately after the workpiece has been inserted, FIG. 5 shows the workpiece being processed, and FIG. 6 shows the situation after the second workpiece has been inserted. Figure 7 is an explanatory diagram of the workpiece, (A) is a cross-sectional view of the workpiece,
(B) is an explanatory diagram of the main part of the surface of the workpiece, FIG. 8 is an explanatory diagram of the conventional example, (A) is a plan view of the spline hole, (B) is a cross-sectional view of the mold, and (C) is a diagram of the surface sag. FIG. l...Forging die, 2...Spline. 2a...land. 2b... Concavity at the top of the land. 2C...Protrusion at the bottom of the land

Claims (1)

[Claims] In a forging die for extruding a spline or a gear on the outer periphery of a solid or hollow cylindrical material, forming a spline shaft or a gear shaft in which a recess is provided in the large diameter part and tooth surface of the land entrance of the forging die. Forging mold.