Bottomed cylindrical piston and method of manufacturing bottomed cylindrical piston

Abstract

By forging a metal material, there is formed a dustproof boot 20 in which a side of an opening end portion 20b formed with a groove 34 for a dustproof boot is provided with a diameter smaller than that of a side of a piston main body 20a, and a total thereof is provided with a substantially uniform wall thickness, thereafter, by carrying out ironing from a front end of the opening end portion 20b to the piston main body side, the recess groove 34 for the dustproof boot can be formed by providing a build-up portion 20c at the opening end portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a disc brake including a bottomed cylindrical piston according to Embodiment 1 of the invention.

FIGS. 2( a) and 2(b) are sectional views showing a procedure of forming a bottomed cylindrical piston by forging.

FIG. 3 is an outline view of a punching machine for forming an opening end portion side of a small diameter of a bottomed cylindrical piston (subjecting mouth-drawing).

FIG. 4 is an outline view of the punching machine for forming a groove for a dustproof boot at a vicinity of an opening end portion.

FIG. 5 is a sectional view of a bottomed cylindrical piston after manufacturing.

FIGS. 6( a) and 6(b) illustrate explanatory views showing a modified example of the bottomed cylindrical piston of Embodiment 1, FIG. 6(a) is a front view of the bottomed cylindrical piston, and FIG. 6(b) is a sectional view taken along a line A-A of FIG. 6(a).

FIG. 7( a) shows Embodiment 2, and is a punching machine for carrying out ironing, FIG. 7(b) is a plane view of a split die split into two, and FIG. 7(c) is a plane view of a split die split into three.

FIG. 8 is a sectional view of a disc brake including a bottomed cylindrical piston of a background art.

FIGS. 9( a) and 9(b) illustrate sectional views of a bottomed cylindrical piston showing a method of forming a groove for a dustproof boot by form rolling in a background art, FIG. 9(a) is an outline view for explaining of forming a groove by a form rolling roll, FIG. 9(b) is a sectional view of a bottomed cylindrical piston as a final product after forming the groove.

Claims

1. A method of manufacturing a bottomed cylindrical piston, wherein the bottomed cylindrical piston is formed with a recess groove for the dustproof boot at an opening end portion, the method comprising: a forging step of processing a metal material to a bottomed cylindrical member by forging;a drawing step of processing an opening end of the bottomed cylindrical member by mouth-drawing so that a diameter of a side of the opening end portion is smaller than a diameter of a side of a piston main body and a total of the bottomed cylindrical member is provided with a substantially uniform wall thickness; andan ironing step of forming a build-up portion at the opening end portion by ironing from a front end of the opening end portion to the side of the piston main body, so that the recess groove for the dustproof boot is formed.

2. The method to according to claim 1, wherein at least one portion of the build-up portion is formed with a notched portion connected with the recess groove for the dustproof boot.

3. The method according to claim 1 or 2, wherein a split die is set to a portion predetermined to form the recess groove for the dustproof boot before the ironing step.

4. A piston comprising: a recess groove for the dustproof boot at an opening end portion of a bottomed cylindrical piston, wherein a diameter of a side of the opening end portion is smaller than a diameter of a side of a piston main body; anda build-up portion provided on a front end of the opening end portion and forming the recess groove between the build-up portion and the piston main body.

5. The piston according to claim 4, wherein the opening end portion is processed to have a small diameter by mouth-drawing.

6. The piston according to claim 4 or 5, wherein the build-up portion is processed by ironing the front end of the opening end portion to the side of the piston main body.

7. The piston according to any one of claims 4 to 6, wherein a wall thickness of the opening end portion is substantially the same with a thickness of a wall thickness of the piston main body.