| 摘要 |
<p>PURPOSE: To suppress the residual stress and to manufacture many types of plastic bent tubes by common molds by applying reverse lateral loads to both the ends of the tube in the state that it is pressed by shorter pressing dies than a bending die, setting a bending angle and the radius of curvature to normal values, and cooling it by pouring water. CONSTITUTION: A plastic tube heated to a softening point is suppressed at the center of a bending die 1, pressed at the pressing surface 21 of a die 2, lateral loads are applied to both the ends of the tube, and excessively bent and molded to the larger bending angle than the normal bending angle of the bent tube and smaller radius of curvature than the normal radius of curvature. In this case, the length L2 of the recess pressing surface 21 of the pressing die 2 is shorter than the length L1 of the bending surface 11 of the bending die 1. Thereafter, after it is naturally cooled to the intermediate temperature of the heating temperature and the ambient temperature, the lateral load of the reverse direction to the load by a cylinder 32 is applied, the bent of the tube is corrected to the normal bending angle and radius of curvature of the bent tube, cooled to be solidified by pouring water as it is, and then the manufacture of the bent tube is finished.</p> |
