| 摘要 |
<p>PURPOSE:To easily manufacture a duplex exhaust pipe having an inner and an outer wall by crushedly molding a steel pipe with a positive and a negative press die and forming a semi-circular pipe having inner and outer walls, and forming a circular exhaust pipe by butt welding the two semi-circular pipes. CONSTITUTION:At manufacture of a duplex exhaust pipe having inner and outer walls, a steel pipe 1 is set in a recessed die 2, inserted sound absorbing material in it if necessary, and a projected die 3 is pressed to it for crush working. hereby a duplex semi-circular pipe is formed, having a clearance 6 between an outer pipe 4 and an inner pipe 5. The duplex semi-circular pipes manufactured in such manner are butted mutually into a circle and butted edges 8 are welded, thus a desired pipe is completed. From such manufacturing method, product accuracy of the exhaust pipe can be improved and cost-down of the exhaust pipe can be realized due to adaptability to mass production.</p> |
