JP2000015381A - Formation of disk parts with shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently forge a disk-shape parts with shaft from a near net- shape blank at a low cost. SOLUTION: An upper die is lowered, and the drawing formation is applied to the portions 10a corresponding to the shaft parts of the bar-like blank at cold state (<=300 deg.C) and the upsetting formation is applied to the portion 10b corresponding to the disk part by compressing in the center axial direction at the warm or the hot state (the transformation temp. or lower). Therein, in the case of applying the upsetting formation to the bar-like blank with the gradient temp. which is highest temp. at the portion corresponding to the outer peripheral part of the disk part and becomes gradually lower temp. toward the center in the radial direction and toward the end parts in the shaft direction from the highest temp. portion, the highest temp. portion does not run into the inner part and the outermost side in the upset portion at the first stage becomes the high temp. portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a disk-shaped component with a shaft having a disk-shaped portion (flange) formed on a part of a shaft, such as a pulley shaft of an automobile, from a rod-shaped material (a billet).

[0002]

2. Description of the Related Art When a disk component with a shaft is formed from a single rod-shaped material, the deformation ratio (drawing ratio and upsetting ratio) of the shaft portion and the disk portion are significantly different. Incongruity with one causes disadvantages on the other. Considering prevention of buckling, the shaft portion is preferably cold, but the disk portion is cracked at the outer periphery when cold.

On the other hand, if the temperature is adjusted between the warm and hot sides in accordance with the disk portion, it is necessary to form a draft in the shaft portion. Particularly, when the temperature is higher than the transformation point, the oxide scale becomes thicker. Must.

Therefore, as a method of forming a disk part with a shaft from a rod-shaped material, a method disclosed in Japanese Patent Application Laid-Open No. 8-332544 has been proposed. In this method, when a long material such as a billet is sandwiched between upper and lower tools, the long material is compressed in the central axis direction by hot working and upset forming, and the long material is attached to the It is intended to prevent buckling by giving a temperature difference.

More specifically, as shown in FIG. 8 (a), the entire long material is once heated to a hot working temperature, and thereafter, as shown in FIG. It is allowed to cool while the heat insulating material is wound around the part to suppress the decrease in the temperature of the intermediate part and to cool the both ends, and then up-molded in this state, and FIG.
The disk component with a shaft as shown in FIG.

[0006]

According to the above-mentioned prior art, in forging a single rod-shaped material, a part can be formed cold and another part can be formed hot. However, when the disk portion is hot-formed, the surface is cooled first and the center portion is cooled and then contracted after the surface layer portion is hardened, so that a crack may be generated in the center portion as shown in FIG. 8 (c). is there. For this reason, it is necessary to slowly cool down, equipment for this is required, and a long time is required.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of molding a disk part with a shaft having a shaft part and a disk part from a rod-shaped material, including the following first step and second step. I did it. (1st process) The part which becomes the outer peripheral part of a disk part after shaping | molding among the surface parts of a rod-shaped raw material is the highest temperature, and gradually from this hottest part toward a radial center and an axial end. Heating the rod-shaped material so that the temperature is reduced. (Second step) In the heated rod-shaped material, a part to be a shaft part is subjected to cold forging, and a part to be a disk part is subjected to warm or hot forging.

Here, the cold forging of the portion to be the shaft portion is generally performed by drawing, and the warm or hot forging of the portion to be the disk portion is generally upset forming.

When the reduction ratio of the shaft portion is large, 1
So that the drawing ratio by the drawing forming of the times becomes a predetermined value or less,
The second step is divided into a plurality of steps, and the warm or hot forging is also divided accordingly.

As a guide of the drawing ratio by one drawing, the drawing ratio is 35% or less, preferably 30% or less. In addition, the division of warm to hot forging in accordance with the division of drawing is performed by dividing the rod-shaped material into an annular shape around the axis of the rod-shaped material, and warming or hot-forging the inner part with the first mold, and then performing the next step. Warm or hot forging the outer annular portion with the die.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a state in which a rod-shaped material is set between upper and lower molds. In the upper mold, an upper die 3 is attached to a die set 1 (see FIG. 3) via a clamp plate 2 and an upper die 3 is provided. An upper knockout 4 and a return spring 5 (see FIG. 3) are provided inside the lower die, and a lower die 8 is attached to a die set 6 via a clamp plate 7.
A lower knockout 9 is provided therein.

A rod material 10 is set between the upper die 3 and the lower die 8. This rod-shaped material 10 is shown in FIG.
Is heated by the heater 11 as shown in FIG. However, the entire bar-shaped material 10 is not uniformly heated, but the portion of the surface portion of the bar-shaped material 10 that becomes the outer periphery of the disk portion after molding is the highest temperature, and from the hottest portion to the center in the radial direction. The heating is performed so that the temperature gradually decreases toward the end in the axial direction.

More specifically, as shown by an isotherm in FIG. 2, the surface of the intermediate portion of the rod-shaped material 10 in the axial direction is set to 600 ° C. or more, and both ends of the rod-shaped material 10 in the axial direction are set to about 100 ° C. To be.

In the present embodiment, the distance between the coil heater 11 and the rod-shaped material 10 is adjusted as a method for imparting the above-mentioned temperature gradient. However, the present invention is not limited to this. Arbitrary means can be adopted, such as changing the number or moving the bar-shaped material.

Next, as shown in FIG. 3, the upper die is lowered, and a portion 10a serving as a shaft portion of the rod-shaped material 10 is drawn under a cold condition (300 ° C. or lower), and a portion 10b serving as a disc portion is formed. Is hot and hot (below the transformation point temperature) in the direction of the central axis to form upset.

FIG. 4 is a diagram showing the temperature distribution of the rod-shaped material 10 immediately after the completion of the first-stage drawing and upsetting as shown in FIG. 3, and as shown in FIG. The outermost portion of the rod-shaped material 10 having the highest temperature is set up, and the rod-shaped material 10 having an inclined temperature is set such that the temperature gradually decreases from the hottest portion toward the center in the radial direction and toward the end in the axial direction. When molding, the hottest part does not enter inside,
The outermost portion of the upset formed portion of the step is the high temperature portion.

If the drawing ratio of the portion 10a serving as the shaft portion is large, a defect is caused. Therefore, when the drawing ratio is large, cold drawing is divided into a plurality of portions. That is, in the present embodiment, after the first-stage drawing and upsetting are completed, the bar-shaped material 10 is set between the upper die 3 and the lower die 8 of another mold device as shown in FIG. Then, the second-stage drawing and upsetting are performed. The drawing is performed on the shaft portion 10a, and the upsetting is performed on the disc-shaped portion 10b.

FIG. 6 is a diagram showing the temperature distribution of the rod-shaped material 10 immediately after the completion of the second-stage drawing and upsetting as shown in FIG. The outermost periphery of the portion 10b is 600 ° C. or higher, and the high-temperature portion does not exist at the center of the portion 10b that becomes the disk-shaped portion.

In the second stage upsetting, an inner portion of the portion 10b to be a disk-shaped portion is formed, and an outer portion (a portion having the highest temperature) is formed in a third stage to be described later. It is formed by upsetting with eyes.

FIG. 7 is a cross-sectional view showing a state where the third-stage drawing and upsetting have been performed. In the third-stage drawing, a portion 10a serving as a shaft portion is subjected to spline processing or the like. The outermost portion of the portion 10b to be a disc-shaped portion is formed. Since the outermost portion is at a high temperature as described above, there is no fear of occurrence of cracks or the like.

Further, the inner part in the radial direction from the outermost part is formed to the final shape by the second stage upsetting,
In the third-stage upsetting, molding is performed only on the outermost portion. By doing so, molding can be performed with a small load.

In the above embodiment, the pulley shaft has been described as an example of a disk part with a shaft, but the present invention is not limited to this. For example, main shaft,
The present invention can be applied to a countershaft, a final gear blank, an assembled crankshaft, a driven face, a hub, a drive shaft, a drive pinion, a housing end, an axle shaft, a balancer, a spline shaft, a flanged bolt, and the like.

[0023]

According to the present invention as described above,
In heating the rod-shaped material before molding, the portion that becomes the outer peripheral portion of the disk portion after molding has the highest temperature, and the temperature gradually decreases from the hottest portion toward the radial center and toward the axial end. Since the temperature gradient is given, the temperature rise in the central part of the material can be suppressed when the disk part is forged by warm or hot, and the surface layer part is cooled even after forging. Since the central portion does not shrink after cooling, it is possible to prevent the center portion from being cracked.

Further, since the shaft portion is cold drawn, if the drawing ratio is large, the drawing is divided into a plurality of portions. At this time, if the warm or hot forging of the portion to be the disc portion is also performed in accordance with this, the disc portion can be efficiently formed. In particular, when performing forging of the disk part by dividing, the part to be forged is divided into a ring shape around the axis of the rod-shaped material, and by forging sequentially from the inner part,
High speed molding with low load becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which a rod-shaped material is set between upper and lower molds.

FIG. 2 is a diagram showing a temperature distribution of a rod-shaped material in the state of FIG. 1;

FIG. 3 is a cross-sectional view showing a state where the first-stage drawing and upsetting are performed;

FIG. 4 is a diagram showing a temperature distribution of the rod-shaped material in the state of FIG. 3;

FIG. 5 is a cross-sectional view showing a state where the second-stage drawing and upsetting are performed;

FIG. 6 is a diagram showing a temperature distribution of the rod-shaped material in the state of FIG. 5;

FIG. 7 is a cross-sectional view showing a state where the third-stage drawing and upsetting are performed;

FIGS. 8A to 8C are diagrams illustrating a conventional molding method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Die set 2 ... Clamp plate, 3 ... Upper die, 4 ... Upper knockout, 8 ... Lower die, 9
... Lower knockout, 10 ... Bar material, 10a ... Shaft portion, 10b ... Disc portion, 11 ... Heater.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E087 AA05 AA10 BA14 BA17 CA17 CA31 CB01 CB02 CB03 DB06 DB15 EA35 EC01 EC22 EC46 EC50 HA31 HA35 HA37

Claims (5)

[Claims] 1. A method for molding a disk part with a shaft having a shaft part and a disk part from a rod-shaped material, comprising the following first and second steps: . (1st process) The part which becomes the outer peripheral part of a disk part after shaping | molding among the surface parts of a rod-shaped raw material is the highest temperature, and gradually from this hottest part toward a radial center and an axial end. Heating the rod-shaped material so that the temperature is reduced. (Second step) In the heated rod-shaped material, a part to be a shaft part is subjected to cold forging, and a part to be a disk part is subjected to warm or hot forging. 2. The method for forming a disk part with a shaft according to claim 1, wherein the part to be the shaft part is cold drawn and the part to be the disk part is upset between warm and hot. A molding method of a disk part with a shaft, characterized by performing molding. 3. The method of forming a disk part with a shaft according to claim 1, wherein the second step is divided into a plurality of parts so that a drawing ratio of the cold forging is equal to or less than a predetermined value. A method for forming a disk part with a shaft, wherein warm to hot forging is also divided. 4. The method for forming a disk part with a shaft according to claim 3, wherein the drawing ratio of the cold forging is 35% or less. 5. The method for forming a disk part with a shaft according to claim 3, wherein the division of the warm or hot forging is performed by dividing the rod-shaped material into a ring shape around the axis of the rod-shaped material, A method for forming a disk part with a shaft, characterized in that after a portion is warm or hot forged, an outer annular portion is warm or hot forged with a next die.