| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a piston enhanced in strength and reducible in weight, in the cup-shaped piston for a disc brake which is required in weight reduction, and a method of manufacturing the same. <P>SOLUTION: The light-weight cup-shaped piston for the disc brake having a groove at its external periphery is characterized in that, when the outside diameter of the piston is denoted as d1, the inside diameter as d2, the wall thickness of a sidewall as t1, the minimum wall thickness of the groove as t2, and the maximum wall thickness of the groove as t3, a constant a expressed by a=(d2/d1)<SP POS="POST">2</SP>is not larger than 0.85, t2 is 0.5 to 1.0 times of t1, t3 is not smaller than 0.9 times of t1, and the hardness (HV) of the cross section center of a t2 portion is not lower than 1.1 to 1.3 times of the hardness (HV) of a t1 portion. After a steel rod is cup-molded into a cup-shaped component by cold forging, compression processing is further applied to an opening of the cup-shaped component by cold forging, and the wall thickness at a position corresponding to the groove of the piston is thickened. After that, the groove is formed by spinning. <P>COPYRIGHT: (C)2013,JPO&INPIT |
