JP2002282991A - Manufacturing method of stepped shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form a product by plastic deformation having a larger diameter stepped part at the middle of an axis member larger than the other part thereof. SOLUTION: A middle part in the axial direction of a bar-like material having a thick hollow member 1 or a solid member is partly heated over a prescribed length and the material is pressed from the both edge in the axial direction to thicken the heated part and expand the diameter of the heated part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a stepped shaft in which a plurality of steps in the axial direction are integrally provided with a stepped portion having a diameter larger than that of another portion. The present invention relates to a method for manufacturing a stepped shaft in which a shape such as a tooth shape is formed on the outer periphery of at least one or more stepped portions.

[0002]

2. Description of the Related Art Conventionally, a stepped shaft of this type is formed by heating a rod-shaped material as a whole to a certain temperature, forging it with a rotary hammer, and forming a stepped shaft having a predetermined shape by hot forging. ing. When a gear is provided on the outer periphery of the step portion of the stepped shaft, the gear is formed in the step portion by machining using a hobbing machine or the like.
When an oil hole is required in the axis of the stepped shaft, the oil hole is formed by a gun drill.

[0003]

In the conventional manufacturing method described above, in the case of a rotary hammer for forming stepped portions provided at a plurality of positions in the axial direction, the equipment becomes large, and a large investment is required. There is a problem.

In order to provide an oil hole in the shaft center, the oil hole must be machined with a gun drill, which is expensive and requires a long machining time.

The present invention has been made in view of the above, and it is possible to easily form a molded product having a stepped portion having a larger diameter than the other portion in the intermediate portion of the shaft member by plastic deformation, A step which allows a predetermined shape such as a gear to be formed by plastic deformation on the outer periphery of a plurality of stepped portions and further allows an oil hole to be provided easily without a gun drill when an oil hole is required at the shaft center. It is an object of the present invention to provide a method of manufacturing a shaft.

[0006]

In order to achieve the above object, a method of manufacturing a stepped shaft according to the present invention comprises the steps of: The material is partially heated over its length, and then the material is pressed from both ends in the axial direction to increase the thickness of the heated portion.

[0007] The stepped shaft is clamped by a split mold, and the stepped shaft is pressed from both sides in the split mold in the axial direction.
The stepped shaft is thickened and formed into a shape along the inner peripheral surface of the split mold.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings, in which a stepped shaft having an oil hole in a shaft center is manufactured.

FIG. 1 shows a thick hollow member 1 having an outer diameter S which is a rod-shaped material of the stepped shaft. If the thick hollow member 1 is not commercially available as a general-purpose product, it is manufactured from other members as a material according to specifications. FIG. 2 shows an example of a manufacturing method of this. As shown in FIG. 2A, for example, a commercially available large-diameter thin-walled hollow material 2 is passed through a reduced-diameter die 3 one or more times to gradually reduce the diameter. The thick hollow member 1 having a predetermined diameter is obtained by reducing the diameter to a thick wall. Further, as shown in FIG. 2B, a hollow member 6 is formed by piercing the center of the solid member 4 with a punch 5. Since the axial length L of the latter thick-walled hollow member 6 is not so long as about 6 times as large as the hole diameter a, it is reduced in diameter by ironing or the like to obtain a predetermined diameter and length. The hollow member 1 has a predetermined thickness.

The thick hollow member 1 obtained in this way is shown in FIG.
As shown in (1), the portions A, B, C, and D at which the diameter is to be increased at a plurality of portions in the axial direction are partially heated in the length direction by high-frequency heating means or the like. The heating temperature and heating length of each of the portions A to D at this time are set according to the diameter and width of the large diameter portion to be obtained. In this embodiment, the portion A is 500 ° C., the portion B is 900 ° C., and the portion C is 110 ° C.
Heating is performed so that the portion of 0 ° C. and D becomes 700 ° C. to obtain a heating material 1a. The heating width of each part is W ₁ , W
₂ , W ₃ and W ₄ .

Then, as shown in FIG. 4, this heating material 1a is lubricated in the hollow hole, the core metal 7 is inserted, and then pressed from both ends in the axial direction with press presses 8a and 8b. Inject molding. As a result, the heated portion is plastically deformed and shortened in the axial direction, and the wall thickness is increased and the large-diameter portions A ′ to D ′ have their widths W ₁ ′ and W ₁ .
₂ ′, W ₃ ′, and W ₄ ′, d having a diameter larger than the original diameter S.
₁ , d ₂ , d ₃ , d ₄ and the first preform material 1
b. At this time, since the heating material 1a is supported by the metal core 7, irregular buckling deformation is prevented.

The procedure for manufacturing the molded product 1e shown in FIG. 8 from the first preformed material 1b obtained in this manner will be described below. That is, the gears 9a, 9b, 9d are formed on the outer periphery of the first, second, and fourth large diameter portions A ', B', D ', and the third large diameter portion C' is stepped. Molding part 9c,
Further, the procedure for forming the small-diameter serrations 9e in the small-diameter portion E 'on one side in the axial direction is as follows.

As shown in FIG. 5, an ironing die 10 is axially press-fitted into one side of the first preforming 1b and the like, and this part is ironed and formed into a small diameter portion E 'having a predetermined diameter. Second
The preformed material 1c is used.

Next, as shown in FIG. 6, this second preform material 1c is formed such that only the portion where the serration 9e is formed on the inner surface is made cylindrical and the other portion is formed into the outer shape of the above-mentioned molded product A. The mold is clamped by being positioned between the split molds 11a and 11b. In this state, the punch 12a, 12b presses in the axial direction from both ends of the second preform material 1c and compresses it into the split molds 11a, 11b. At this time, the divided molds 11a and 11b are filled with the material 1c by the compression thickening, and the outer diameter of the material 1c is changed to the divided molds 11a and 11b.
The third preform material 1d shown in FIG. 7 is obtained by being formed into the inner peripheral shape of FIG. And this material 1d has the first and second
-The third gears 9a, 9b, 9d and the stepped portion 9c are formed. The molding at this time is performed by cold forging. It may be warm.

Next, a serration 9e is formed on the small diameter portion E 'of the third preform material 1d by roll forming or press forming to obtain a molded product 1e.

In each of the above steps, the first preformed material 1
The diameters of the large diameter portions A ', B', C ', D' of b correspond to the gears 9a, 9b, 9d and the stepped portion 9c to be formed in this portion.
Of the gears 9a, 9
In the case of b and 9d, the diameter is slightly smaller than the root circle of each gear.
In the case of the stepped portion, the thickness is increased by plastic deformation so as to be slightly smaller than the outer diameter of the stepped portion 9c. The wall thickness of the plastically deformed portion is determined by the heating temperature and the heating width of the portion, and these are experimentally selected empirically.

In this embodiment, since the thick hollow member 1 is used as a material, a hole 13 remains in the axis of the molded product 1e, which can be used as an oil hole passing through the axis.

When it is not necessary to provide the hole 13 in the shaft center, for example, when the oil hole is not required in the molded product 1e, a solid member may be used as the material.

For these materials, high carbon steel or high carbon steel to which B is added is used. The material between the steps may be subjected to an appropriate heat treatment such as annealing. Then, the gear portion of the molded product is subjected to heat treatment such as induction hardening.

In the above embodiment, the step shown in FIG. 4 and the step shown in FIG. 5 may be performed simultaneously. That is, the raw material 1a that has been subjected to the predetermined heating may be pressed in the axial direction while being squeezed by the squeezing mold 10, and the thickness of the heating unit may be increased at the same time as the squeezing.

Further, in this embodiment, an example is shown in which a plurality of steps are provided in the middle of the shaft member, but this step may be provided only at one place.

[0022]

According to the present invention, it is possible to easily form a molded product having a stepped portion having a larger diameter than the other portion (material diameter) in the middle portion of the shaft member by plastic deformation. Even when a plurality of the steps are provided in the axial direction, the molding can be similarly easily performed.

The shape of a gear or the like can be formed by plastic deformation on the outer periphery of the step portion by plastic deformation. Furthermore, by using a rod-shaped material for the molded product, a hole serving as an oil hole can be formed in the axis of the molded product, and the oil hole can be formed without post-processing such as a gun drill.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a thick hollow member.

FIGS. 2 (a) and 2 (b) are process diagrams showing a method for producing a thick hollow member.

FIG. 3 is an explanatory view showing a heating material.

FIG. 4 is a process chart of a first preform material.

FIG. 5 is a process chart of a second preform material.

FIG. 6 is a working process diagram for plastically working a gear or the like on the outer periphery of a second preform material.

FIG. 7 is a sectional view showing a third preform material.

FIG. 8 is a sectional view showing a molded product.

[Explanation of symbols]

1: thick hollow member, 1a: heating material, 1b, 1c, 1d
1st, 2nd, 3rd preformed materials, 2 large diameter thin hollow materials, 3 reduced diameter dies, 4 solid members, 5 punches, 6
Hollow member, 7: core metal, 8a, 8b: push table, 9a, 9b,
9d: gear, 9c: stepped portion, 9e: serration, 10
... Ironing die, 11a, 11b ... Split die, 12a, 1
2b: punch, 13: hole.

Claims (2)

[Claims] 1. An axially intermediate portion of a rod-shaped material made of a thick hollow member or a solid member is partially heated over a predetermined length, and then the material is pressed from both ends in an axial direction to heat the heating portion. A method for manufacturing a stepped shaft, characterized in that the diameter of the stepped shaft is increased. 2. The stepped shaft according to claim 1 is sandwiched between divided molds, and the stepped shaft is pressed from both axial sides in the divided mold.
A method of manufacturing a stepped shaft, comprising increasing the thickness of the stepped shaft to a shape along the inner peripheral surface of a split mold.