| 摘要 |
PURPOSE:To improve the jointing strength between a box body and an inner tube by providing a circular groove having a thin thread on the surface of the inner tube to be connected to the box body in a blow molding of a muffler for reduction of noise comprising the box body and the inner tube. CONSTITUTION:In the manufacture of a resonance type silencer 30 in which a box body 28 is mounted integral on the circumference of an inner tube 21 having a tiny hole 22, the inner tube 21 having the tiny hole 22 is mounted on a slide core 4 and then, is lifted so as to position the inner tube 21 inside a parison 20 molded with a cross head 1. Then, dies 12 and 16 are closed and air is sent from a path 5 to blow mold the parison into a box body 28 while integrating both the inner tube and the box body. As resin at the connection end of the box body 28 penetrates into a circular groove 23 provided on the surface of the inner tube or the circular thin thread melts integral therewith, both parts can firmly join together thereby serving for reduction in the noise of engines for automobile. |
