Sheet metal member having an annular peripheral wall and a method of thickening an annular peripheral wall of the member
The invention relates to a sheet metal member having an annular peripheral wall and a method of thickening an annular peripheral wall of the member. In the invention, the thickness of the annular peripheral wall is increased to be 2 or more times or 3 or more times that of a base plate. Teeth for a timing toothed belt, a gear, or the like are cut in the annular peripheral wall which is thickened in this way. In the method of thickening an annular peripheral wall of the invention, a base plate integrally having a flange-shaped portion is held between a circular bottom pattern tool and a circular top pattern tool, the flange-shaped portion which is projected outside and the circular top pattern tool is sequentially pressed in a radially inward direction by annular forming faces of circular rollers of plural kinds, thereby thickening the flange-shaped portion, and the flange-shaped portion is then formed into a cylindrical shape which is concentric with the base plate. According to the method, it is not required to separately produce the peripheral wall and the base plate and then weld them with each other, and the peripheral wall can be provided with a strength required for cutting teeth in the peripheral wall.
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The present invention relates to a sheet metal member having an annular peripheral wall, such as a drive plate, and also to a method of thickening an annular peripheral wall of the member, and particularly to a technique wherein a disk-shaped sheet metal member having a small thickness is used and an annular peripheral wall having a thickness which is several times the thickness of the sheet metal member. The thickened annular peripheral wall of the invention is suitable for cutting teeth to be engaged with a timing toothed belt, a gear, or the like. Teeth which are cut in this way have a sufficient strength and thickness, and are suitable particularly for the use as an automobile part.
BACKGROUND ART In a drive plate used in a starter for starting an engine of an automobile, teeth are formed on a peripheral wall disposed in the outer peripheral portion of a disc-like base plate.
Even when the peripheral wall member 4 itself has a strength and thickness sufficient for cutting the teeth 3, however, such a drive plate has problems such as that defects due to welding failures are easily produced, and that an expensive automatic welding robot is required.
The present invention has been conducted in view of the above-mentioned circumstances. It is an object of the invention to provide a sheet metal member and a method of thickening an annular peripheral wall of the member in which, in a member wherein an annular peripheral wall is formed on a base plate as seen in a drive plate, the base plate and the annular peripheral wall are integrated with each other and teeth can be directly cut in the annular peripheral wall without causing the member to have an insufficient strength.
DISCLOSURE OF THE INVENTIONIn order to attain the above-mentioned object, in the sheet metal member of the invention, a base plate and an annular peripheral wall which extends in a perpendicular direction from the outer periphery of the base plate are integrally formed, and the thickness of the annular peripheral wall is increased to be 2 or more times or 3 or more times the thickness of the base plate.
As a result of the success of the thickening method which will be described later, in the sheet metal member of the invention, the annular peripheral wall is thickened by a factor of 2 or more, or 3 or more which is unexpected in the prior art. Therefore, teeth, which are cut in a peripheral wall member of a drive plate of the prior art, can be directly cut in the outer face of the annular peripheral wall. Consequently, it is possible to eliminate two steps which are conducted in a drive plate of the prior art, i.e., the steps of fitting the peripheral wall member 4 wherein the teeth 3 are cut, into the cylindrical portion 2 of the sheet metal member, and welding the peripheral wall member 4 to the cylindrical portion 2. Furthermore, since the base plate uses a sheet metal member which is thinner than the annular peripheral wall or has a smaller thickness, the weight and the material cost are prevented from being increased.
The method of thickening the annular peripheral wall 2 or more times or 3 or more times comprises the steps of: holding a base plate of a disc member having the base plate and a flange-shaped portion integrally formed in the outer periphery of the base plate, between a circular bottom pattern tool and a circular top pattern tool; sequentially pressing the flange-shaped portion projected outside the circular bottom pattern tool and the circular top pattern tool, in a radially inward direction by recessed annular forming faces of circular rollers of plural kinds each having a recessed annular forming face, thereby sequentially thickening the rear side of the flange-shaped portion; and forming the thickened flange-shaped portion into a cylindrical shape which is concentric with the base plate, to form a thickened annular peripheral wall, thereby attaining the thickening in which the thickness of the annular peripheral wall of the sheet metal member is 2 or more times or 3 or more times that of the base plate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 6 show an embodiment wherein a drive plate which is to be used in a starter for starting an engine of an automobile is produced by applying the method of thickening an annular peripheral wall according to the invention to a thin disc member which is made of a steel plate and serves as a sheet metal member. A disc member 11 used as a starting material has a thickness t1 of 2 mm. The method of thickening an annular peripheral wall according to the invention is applied to the disc member 11. The disc member 11 comprises a base plate 12 and a flange-shaped portion 13 which is integrated to the outer side of the plate. The flange-shaped portion 13 may be continuous with the base plate 12 in a flat manner or continuous with the plate via a stepped portion. In the embodiment, as shown in
In the drawing step of
FIGS. 2 to 5 show stages of a step in which the disc member 11 is held between a circular bottom pattern tool 33 and a circular top pattern tool 34 and the flange-shaped portion 13 is gradually thickened by using circular rollers 35 to 38 of several kinds.
The circular roller 35 used in the step of
The circular roller 36 used in the step of
The circular roller 37 used in the step of
The circular roller 38 used in the step of
The flange-shaped portion 13 which is thickened by conducing the stages described with reference to FIGS. 2 to 5 enters a state in which the portion is nearly formed into a peripheral wall. The thickness (the thickness in a radial direction) of the flange-shaped portion 13 (peripheral wall) can be made 3 or more times that of the base plate 12.
In the embodiment described with reference to FIGS. 1 to 6, the thickened annular peripheral wall 17 which is eventually formed is about 7 mm, or it was possible to form the annular peripheral wall 17 having a thickness which is 3.5 times that of the base plate 12 (thickness of 2 mm). It is a matter of course that, when the preset conditions such as the angles of the annular forming faces 42, 45, 48, 52, 54 of the circular rollers 35 to 38, 53 are changed, the thickness of the annular peripheral wall 17 may be set to be 3.5 or less times (for example, 2 or 3 times) or 3.5 or more times that of the base plate 12.
FIGS. 7 to 12 are partial end views showing the accurate shapes of the member which are obtained by conducting the stages or steps described with reference to FIGS. 1 to 6. Specifically,
According to the sheet metal member having an annular peripheral wall, and the method of thickening an annular peripheral wall of the member of the invention, an annular peripheral wall integrated with a base plate is thickened to a level which is 2 or more times or 3 or more times the thickness of the base plate. When teeth are cut in the outer peripheral face of the thickened annular peripheral wall, for example, a drive plate can be produced. In this case, a welding process is not required, and the weight and the material cost are prevented from being increased. Therefore, the invention is effective particularly in the case where a welding process is to be eliminated and the material cost is to be lowered.
Claims
1-5. (canceled)
6. A method of forming a thickened annular peripheral wall of a sheet metal member, comprising the steps of: holding the sheet metal member and forming from the sheet metal member a base plate, a stepped portion and a flange-shaped portion connected integrally by the stepped portion with an outer periphery of the base plate; inserting the base plate, the stepped portion and at least a port of the flange-shaped portion between a circular bottom pattern tool and a circular top pattern tool; applying recessed annular forming faces of circular rollers of plural kinds against the flange-shaped portion and sequentially pressing the flange-shaped portion projecting outwardly from the circular bottom pattern tool and said circular top pattern tool, in a radially inward direction, thereby sequentially thickening a rear side of the flange-shaped portion; and forming the thickened flange-shaped portion into a cylindrical shape which is concentric with the base plate, thereby forming the thickened annular peripheral wall.
7. The method as defined in claim 6, wherein the flange-shaped portion is inclined relative to the base plate during the forming step.
Type: Application
Filed: Feb 3, 2006
Publication Date: Jun 15, 2006
Applicant:
Inventors: Toshiaki Kanemitsu (Kobe-shi), Shuji Kanemitsu (Kakogawa-shi), Hironori Nishioka (Kobe-shi)
Application Number: 11/346,259
International Classification: B21H 1/02 (20060101);