JPH10274316A - Molding method of corner part by press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of press molding capable of suppressing reduction of plate thickness in a corner part in a peripheral part of a front cover, so that material plate thickness can be thinned with strength kept as it is, attain reduction of a cost of production and lightening of weight of a torque converter. SOLUTION: A molding method of a peripheral corner part 34 of a front cover 3 of a torque converter is a method performing bending work by a press on a material, first/second process are provided. In the first process, the peripheral corner part 34 is preliminarily pressed. In the second process, the peripheral corner part 34 pressed preliminarily in the first process, while applying compression force in the direction crossing the thickness direction of the material, is finish pressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a corner by pressing a corner, and more particularly to a method of forming a corner of an outer peripheral portion of a front cover of a torque converter.

[0002]

2. Description of the Related Art A torque converter is a device having three types of impellers (impeller, turbine, and stator) therein and transmitting torque by operating hydraulic oil. The impeller is fixed to a front cover connected to a rotating body on the engine side, and torque is transmitted to the transmission side by hydraulic oil flowing from the impeller to the turbine.

The front cover, which is a component of the torque converter, is often formed by pressing. This front cover is shaped like the front cover 3 shown in FIG. 1 and has a plate thickness of 4 to 6 mm, and has a curved portion with a radius dimension substantially equal to the plate thickness on the outer peripheral portion.

[0004]

When the front cover having the above-mentioned shape is press-formed, the thickness of the curved portion at the outer peripheral portion is reduced. In order to suppress the decrease in the sheet thickness, a method of gradually forming is usually adopted by performing a preliminary press before performing a finish press. However, the reduction in thickness at present is 7% less than the thickness of the material.
% Or more, and conventionally, the thickness of the material is increased in order to avoid a decrease in strength due to the reduction in thickness. As a result, the thickness of the material is increased, the production cost is increased, and the weight of the torque converter is also increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a press forming method capable of suppressing a decrease in the thickness of a corner portion. Is to reduce the weight of the vehicle.

[0006]

A method of forming a corner according to claim 1 is a method of forming a corner when a material is bent by a press, comprising: a first step;
A second step. In the first step, a corner portion of the material is preliminarily pressed. In the second step, finishing press is performed on the corner portion preliminarily pressed in the first step while applying a compressive force to the corner portion in a direction intersecting the thickness direction of the material.

Conventionally, no countermeasures (methods) have been taken in the finishing press in which only a pressing force is applied in the thickness direction, and the extension of the material including the corners is actively restricted. Here, since a compressive force is applied to the corner portion in a direction intersecting the thickness direction of the material during the finishing press, it is possible to suppress a decrease in the sheet thickness due to the extension of the corner portion. As a result, the thickness of the corner portion after molding becomes larger than before, and the thickness of the material can be reduced while maintaining the strength, thereby reducing the production cost.

According to a second aspect of the present invention, there is provided a method of forming a corner portion according to the first aspect,
The corner portion of the outer peripheral portion of the front cover of the torque converter is formed. Here, in the corner of the outer peripheral portion where the bending dimension is severe in the shape of the front cover,
The corner forming method described in (1) is adopted. As a result, the thickness of the front cover can be reduced, and the weight of the torque converter can be reduced while ensuring strength.

The method of forming a corner according to claim 3 is a method of forming a corner according to claim 2, wherein
The reduction rate of the thickness of the corner portion which is finish-pressed with respect to the thickness of the front cover is 5% or less. Under these conditions, the rate of reduction in the thickness of the corner portion is 15 to 20% in the related art.
It is. On the other hand, according to the molding method of the present invention, the thickness can be reduced to 5% or less, and a material having a small thickness can be used for the front cover.

[0010]

FIG. 1 shows a torque converter 1 including a front cover 3 formed according to an embodiment of the present invention. Here, OO is a rotation shaft of the torque converter 1, and an engine (not shown) is shown on the left side of the figure.
Are arranged, and a transmission (not shown) is arranged on the right side of the figure.

The torque converter 1 is a mechanism for transmitting torque from a crankshaft on the engine side to a main drive shaft of the transmission, and mainly includes a front cover 3 connected to the crankshaft on the engine side via a flexible plate. , An impeller 4, a turbine 5, and a stator 6. The front cover 3 and the impeller shell 4a of the impeller 4 are welded at an outer peripheral portion, and both form a hydraulic oil chamber.

The front cover 3 has a disk-shaped main body 32.
, A boss portion 31 and an outer peripheral connecting portion 33, and an outer peripheral corner portion 34 is formed between the main body portion 32 and the outer peripheral connecting portion 33. The boss 31 is attached to the main body 3
2 for positioning and centering the engine-side components. The outer peripheral connection portion 33 has a cylindrical shape and is formed on the outer peripheral side of the main body portion 32,
The transmission side end is fixed to the outer peripheral portion of the impeller shell 4a. The method of forming the outer peripheral corner portion 34 of the front cover 3 will be described later.

The impeller 4 includes an impeller shell 4a, a plurality of impeller blades 4b fixed inside the impeller shell 4a, and an impeller hub 4c fixed to the inner peripheral end of the impeller shell 4a. The turbine 5 is provided in the hydraulic oil chamber with the main body 41 of the impeller shell 4a.
, And mainly includes a turbine shell 5a and a plurality of turbine blades 5b fixed to the turbine shell 5a. A turbine hub 8 having a spline hole 8a for connection with a main drive shaft extending from the transmission side is fixed to an inner peripheral end of the turbine shell 5a.

The stator 6 is disposed between the impeller 4 and the turbine 5 and is fixed via a one-way clutch 7 to a stator shaft fixed to a transmission housing. Next, the operation of the torque converter 1 will be described. The torque from the engine side crankshaft is input to the front cover 3 from a flexible plate (not shown). This torque is transmitted to the impeller shell 4a. As a result, the impeller 4 rotates, and the hydraulic oil flows from the impeller shell 4a to the turbine 5 side. This flow of the hydraulic oil causes the turbine 5 to rotate, and the torque of the turbine 5 is output to the main drive shaft via the turbine hub 8.

Next, a method of forming the outer peripheral corner portion 34 of the front cover 3 will be described. First, a disk-shaped steel plate cut out from a plate material as a raw material is preliminarily pressed a plurality of times to form the front cover 3 shown in FIG. Next, using the mold 11 and the mold 12 shown in FIGS. 2 and 3, finish molding by press is performed.
Here, as shown in FIG. 2, the molding is performed by pressing down the mold 11 against the impeller shell 4a placed on the mold 12. In this finish molding, the end (upper end in FIG. 2) of the outer peripheral connection portion 33 of the front cover 3 on the side opposite to the outer peripheral corner 34 is placed on the surface 1 of the mold 11 shown in FIG.
1a pushes down. That is, mainly the outer peripheral connection portion 33
In addition, a compressive internal stress acts on the outer peripheral corner portion 34 in a direction orthogonal to the thickness direction (see the arrow of the force direction in FIG. 3). Thereby, the thickness reduction due to the extension of the outer peripheral corner portion 34 is suppressed, or conversely, the outer peripheral corner portion 34 is compressed to increase the plate thickness, and the outer peripheral corner portion 34 shown in FIG. The thickness is greater than before. For this reason, the thickness of the plate material, which is a material, can be made smaller than before while maintaining strength, and the production cost is reduced.

When a compressive force does not act on the outer peripheral corner portion 34 in the finishing press as in the prior art,
When the material thickness of 5.00 mm is bent and press-formed, the thickness of the formed material is 4.40 to 4.55 mm, which is a decrease of about 9%. On the other hand, if the forming method of the present embodiment is adopted, the plate thickness after forming when the plate thickness of the material is 5.00 mm similarly bent and pressed is 4.95 to 5.10.
mm, and there is almost no thickness reduction.

[0017]

According to the present invention, a reduction in the thickness of the corner portion is suppressed by applying a compressive force to the corner portion in a direction intersecting the thickness direction of the material during the finishing press. The plate thickness becomes thicker than before, and the material plate thickness can be reduced while maintaining the strength, thereby reducing the production cost.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a torque converter including a front cover formed according to an embodiment of the present invention.

FIG. 2 is a finishing press diagram.

FIG. 3 is a finishing press diagram.

[Explanation of symbols]

 1 Torque converter 3 Front cover 34 Outer corner (corner)

Claims (3)

[Claims] 1. A method of forming a corner portion when a material is subjected to a bending process by a press, comprising: a first step of preliminarily pressing a corner portion of the material; Finishing press the corner portion while applying a compressive force to the corner portion in a direction intersecting the thickness direction of the material.
And a method for forming a corner portion comprising: 2. The method according to claim 1, wherein the corner of the outer periphery of the front cover of the torque converter is formed. 3. The corner forming method according to claim 2, wherein a reduction rate of the thickness of the corner portion pressed and finished with respect to the thickness of the front cover is 5% or less.