| 摘要 |
PURPOSE:To prevent breakage at any portion of cam by using a bulge metal die provided with an elastic member applied to the cam supporting surface, and applying compressive force to the elastic member when die is set up for the bulge forming process, thus maintaining initial compressive load at the area of protrusion. CONSTITUTION:The pipe material 1' is inserted in position to the fixed half of the metal die 10 of bulge process, and other half of the die 10 assembled by means of a guide pin 15, and two halves tightened up. At this moment, an elastic member 14 is squeezed between the protruding area 2 and the supporting surface 11 of cam so that initial compressive load directing inward is imposed on the protruding area of the elastic member 14. Under such condition, emulsion liquid is introduced into the pipe 1' and pressure applied forcing the pipe 1' bulge out. As the pipe bulge outward, tensile stress is generated, however, because of the initial compressive load imposed by the elastic member 14, part of the tensile stress is cancelled, so that the maximum tensile stress at the cam area 2 is considerably reduced. |
