| 摘要 |
A sheet feed roller is provided which is free of a circumferential bulge on a sheet sliding contact surface of a roller portion, thereby improving the quality of images formed by an electrophotographic device. In a sheet feed rolling element for use in an electrophotographic device including a roller portion (1) and shoulders (3) on both sides which are formed by curved chamfers, the parting line (PL) (14) between the fixed mold plate (11) and the movable mold plate (12) of a mold for injection molding is located at the boundary between one of the shoulders (3) and the outer periphery (4) of the roller portion (1), a step (8) is provided at the boundary due to a difference between the opening diameter (m1) of the portion of the cavity defined by the mold plate (11) and the opening diameter (m2) of the portion of the cavity defined by the mold plate (12) so that the one shoulder (3) has a smaller diameter than the outer peripheral surface (4), and a chamfer (17) is provided on the portion of the roller portion (1) adjacent to the one shoulder (3) so as to absorb any difference in molding shrinkage rate due to a difference in molecular orientation of resin at the step (8), thereby preventing a circumferential bulge on the outer periphery (4) of the roller portion (1) after the roller has been formed. |
