| 摘要 |
PURPOSE:To enable a recessed groove to be formed in a desired depth, by forming the recessed groove with a bottom internal angle of a horizontal line larger than the upper internal angle of the horizontal line and preventing the generation of a thickness lack. CONSTITUTION:A urethane bound bumper 11, providing on its external surface a plurality of recessed grooves 12, 12, adjusts a spring characteristic while giving the foldability. While the bumper 11 forms the recessed grooves 12, 12 so that an internal angle theta2 formed in the bottom of a horizontal line H may become larger than an internal angle theta1 formed in the upper of the horizontal line passing through the center of the recessed groove 12, 12. That is, the bumper 11, forming the upper part in a small angle further the bottom part in a large angle of the horizontal line H of the recessed grooves 12, 12, enables many recessed grooves having a desired depth to be formed with no generation of a thickness lack. |
