JPS6142131B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a clutch piston used in clutches such as multi-disc friction clutches and automatic transmission devices.

More specifically, the inner and outer diameter parts of a disc material with a hole formed in the center are formed into a cylindrical shape, the central and peripheral cylindrical parts are thickened, and a groove for a sealing member is formed in these parts. The present invention relates to a manufacturing method for efficiently manufacturing a clutch piston by combining drawing, upsetting, and forward extrusion methods.

Conventionally, this type of clutch piston has generally been cast, which has caused problems such as production being troublesome, complicated, and high in cost.

Therefore, a method of obtaining the clutch piston by press molding has been proposed. For example, in JP-A-53-64144, a hole is bored in a disc-shaped member, the inner diameter part is formed into a cylindrical shape, the outer diameter part is formed into a cylindrical shape, and then the clutch piston is formed into a cylindrical shape. The parts are folded and stacked one on top of the other to increase the wall thickness and create a groove for the sealing member on the outer periphery.

This conventional method requires an extra process because it is formed into a cylindrical shape and then folded and overlapped, and it is difficult to say that it is the best for forming, as it has poor workability and a large forming load. Since it is left as it is, it is not possible to form a groove, and it is necessary to create a groove for the seal member on the shaft side where the piston is fitted.

The present inventors have devised the present invention in order to efficiently manufacture this type of clutch piston, and an object of the present invention is to combine drawing, upsetting, and forward extrusion to produce a central and outer diameter cylindrical portion. To provide a method for manufacturing a clutch piston, in which a thickened part is formed in the part, a groove for a sealing member can be formed in this part, and a clutch piston having excellent structure can be formed easily and efficiently. It is in.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a multi-plate friction clutch, and a clutch for an automatic transmission is constructed in approximately the same manner, with a friction plate d disposed between an outer b and an inner c provided on a shaft a. A clutch piston e disposed between them is hydraulically slid, and the friction plates d are frictionally engaged to transmit power.

The clutch piston e described above is molded through the steps shown in FIGS. 2 to 5.

As shown in FIG. 2, a circular small hole 2 is punch-formed in the center of a steel sheet material 1 having circular dimensions, and this small hole 2 is formed together with the material 1 when it is punch-formed.

Next, as shown in FIG. 3, the portion of the small hole 2 is enlarged by drawing, and the peripheral portion thereof is drawn into a cylindrical shape in one direction to form the central cylindrical portion 3. At the same time, the outer circumferential edge part is raised in the opposite direction to the cylindrical part 3 to form the outer cylindrical part 4, and the inner part of the outer periphery cylindrical part 4 is moved radially toward the central cylindrical part 3 in a predetermined direction. The spring seat 5 is formed by rolling it into an annular shape over its length.

Further, the axial end of the central cylindrical portion 3 is upset-molded to shrink it to a predetermined length in the axial direction, thereby forming a thickened portion 6 in the cylindrical portion 3. Then, the outer circumferential cylinder part 4 is formed by forward extrusion molding to form a thin extruded part 7 at the front and bulge in the radial direction at the part continuous with the plate-like main body 8 and at the rear part to form a thickened part 9. It is shown in Figure 4. The above steps are performed simultaneously while applying molding loads in opposite directions in the axial direction to the cylindrical portions 3 and 4. still,
The reason why the outer cylindrical portion 4 was formed by extrusion molding rather than upsetting in this embodiment is because the outer cylindrical portion 4 is used as a sliding surface and requires a predetermined length in the axial direction. In other words, if upsetting is performed on the raised outer circumferential cylinder part 4, the thickness of the outer circumferential cylinder part 4 can be increased, but the radial length of the clutch piston will be reduced, and such a clutch piston cannot be used. This is because if it is assembled into a clutch, it may fall down. For these reasons, extrusion molding was used in this example. Also, the reason why the thickness of the outer cylindrical part 4 is made different between the front and back parts of the plate-like body is to restrict the flow of the meat of the outer cylindrical part 4 when extrusion molding is performed, thereby ensuring that the thickness of the outer cylindrical part 4 is increased. This is to make it happen. That is, if the outer cylindrical portion 4
If the wall thickness is the same on the front and back, when a force in the axial direction of the plate-like body is applied to the outer cylinder part 4 during extrusion molding, the outer cylinder part 4 will easily break from the plate-like body due to shearing. There is a possibility that this may occur, and in order to prevent this, in this embodiment, the thickness of the outer circumferential cylinder portion 4 at the front and rear is changed.

Therefore, in this embodiment, when the outer circumferential cylinder part 4 is formed by extrusion molding as shown in FIGS. The rising part of the outer cylinder part 4 is thick and the lower part is thin, so that the inner wall surface of the rising part of the outer cylinder part 4 (the part above the plate-like body in Fig. 4) and the outer cylinder are thick. Lower part of section (4th
The position of the inner wall surface of the inner wall (the part below the plate-shaped main body in the figure) is different, and when the meat flows downward from the raised part of the outer cylindrical part, a moderate resistance is generated, and the outer periphery cylindrical part 4 becomes the plate-shaped main body. This prevents the problem of the product breaking.

Grooves are formed on the inner diameter of the central thickened portion 6 of the molded product 10 obtained above to form O-ring grooves 11, and grooves are formed on the outer diameter of the portion of the outer diameter thickened portion 9 that extends over the main body 8. Then, the O-ring grooves 12 are machined to obtain a clutch piston e as shown in FIG. 5. In this embodiment, the wall thickness of the outer cylindrical portion 4 was made thinner on the spring receiving side and thicker on the opposite side, but this may be reversed. All you have to do is make one of the front and back thicker and the other thinner.
The aim is to increase the thickness of the meat. There is no problem even if a clutch plate having a wall thickness opposite to that of the front and rear of the outer circumferential cylinder portion of this embodiment is incorporated into the clutch.

As is clear from the above, according to the present invention, a clutch piston can be formed easily and efficiently by a combination of drawing forming, upsetting, and forward extrusion forming, without the need for bending or overlapping the ends.
In particular, since processes similar to forging such as bending and overlapping are not performed, the forming load is small, which is advantageous in terms of energy conservation.The press machine itself does not need to maintain strength and rigidity to withstand large loads, and the press machine itself is simple. In addition to the fact that it is possible to machine an O-ring groove in the inner diameter part of the central cylindrical part, there is no need to machine a groove in the other party, and the clutch itself has many advantages such as being easier to manufacture. In addition, in the present invention, when increasing the thickness of the outer circumferential tube, it is done by extrusion molding, so the length in the axial direction of the outer circumferential tube can be ensured, and the outer circumferential tube can be thickened at the front and back with the plate-shaped main body in between. Since the wall thicknesses are made different, it is possible to prevent the outer circumferential cylindrical portion from being damaged during molding and to increase the thickness reliably.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a clutch, and FIGS. 2 to 5 are cross-sectional views showing the manufacturing method of the present invention in the order of steps. In the drawing, 1 is the material, 2 is a small hole, 3 is a central cylindrical part, 4 is an outer peripheral cylindrical part, 6 and 9 are thickened parts, 7 is a thin extruded part, and 11 and 12 are grooves for sealing members. be.

Claims (1)

[Scope of Claims] 1. A steel plate material with a small hole drilled in the center of the circular shape is formed into a cylindrical shape around the hole and the outer diameter, and the end of the cylindrical part in the center is formed by upsetting, and the outer periphery is The thickness of the cylindrical part is increased by extrusion molding, and a groove for a sealing member is formed on the inner diameter of the increased thickness of the central cylindrical part, and a groove for a sealing member is formed on the outer diameter of the increased thickness of the outer peripheral cylindrical part. A method for manufacturing a clutch piston, characterized in that: 2. The method of manufacturing a clutch piston according to claim 1, wherein the outer circumferential cylindrical portion has different wall thicknesses at the front and rear sides of the disc-shaped main body.