Abstract: A metallic bellows is manufactured by a first step of bulging a straight raw pipe into a primary formed body having formed on a periphery thereof a corrugated bellows section, and a second step of subjecting at least one of crest portions and trough portions of the bellows section of the primary formed body to roll machining by means of a pair of forming rolls.

Abstract: A metallic bellows is manufactured by a first step of bulging a straight raw pipe into a primary formed body having formed on a periphery thereof a corrugated bellows section, and a second step of subjecting at least one of crest portions and trough portions of the bellows section of the primary formed body to roll machining by means of a pair of forming rolls.

Abstract: In manufacturing an exhaust pipe of two-passage construction, a metallic plate having a first end and a second end respectively elongated in a longitudinal direction of the exhaust pipe is prepared. The metallic plate is bent into a substantially S shape in cross section. It has a diametrically extending central partition plate and a substantially semicircular peripheral wall on each lateral side of said partition plate in such a manner that a groove of substantially V shape in cross section having a substantially closed end on a radially inner side and an open end on a radially outer side is formed at each diametrically outer portion of the partition plate. A target is provided so as to elongate along the groove in a manner to extend substantially radially outward from the closed end. A welding arc is generated between the target and a welding gun disposed on a side of the open end such that the substantially closed end and the target are welded together.

Abstract: In manufacturing an exhaust pipe of two-passage construction, a metallic plate having a first end and a second end respectively elongated in a longitudinal direction of the exhaust pipe is prepared. The metallic plate is bent into a substantially S shape in cross section. It has a diametrically extending central partition plate and a substantially semicircular peripheral wall on each lateral side of said partition plate in such a manner that a groove of substantially V shape in cross section having a substantially closed end on a radially inner side and an open end on a radially outer side is formed at each diametrically outer portion of the partition plate. A target is provided so as to elongate along the groove in a manner to extend substantially radially outward from the closed end. A welding arc is generated between the target and a welding gun disposed on a side of the open end such that the substantially closed end and the target are welded together.

Abstract: An exhaust pipe assembly of two-passage and double-pipe construction has an inner pipe; a partition plate meeting the inner pipe at both diametrical meeting ends thereof so as to be elongated in a longitudinal direction of the inner pipe. Two passages divided across a diameter of said inner pipe are thus formed. The assembly also has an outer pipe which covers the inner pipe with a thermally insulating space around a periphery of the inner pipe. The outer pipe has on one longitudinal end thereof a connecting portion for connection with a mating member. One end of the inner pipe is fixedly connected to the outer pipe with a clearance between the periphery of the inner pipe near each of the meeting ends and an inner circumference of the outer pipe.

Abstract: In manufacturing an exhaust pipe of two-passage construction, a metallic plate having a first end and a second end respectively elongated in a longitudinal direction of the exhaust pipe is prepared. The metallic plate is bent into a substantially S shape in cross section. It has a diametrically extending central partition plate and a substantially semicircular peripheral wall on each lateral side of said partition plate in such a manner that a groove of substantially V shape in cross section having a substantially closed end on a radially inner side and an open end on a radially outer side is formed at each diametrically outer portion of the partition plate. A target is provided so as to elongate along the groove in a manner to extend substantially radially outward from the closed end. A welding arc is generated between the target and a welding gun disposed on a side of the open end such that the substantially closed end and the target are welded together.

Abstract: A silencer comprising an outer sleeve made of a aluminum or an aluminum alloy, an inner sleeve made of a iron or steel, and acoustic material inserted between the outer sleeve and the inner sleeve. An end cap for closing a downstream end of the silencer comprising a first member made of iron or steel which is formed into a shape of the end cap, and a second member made of aluminum metal which is formed into the same shape as the outline of the first member, the peripheral portion of the first member and the peripheral portion of the second member being laminated. An end plate made of aluminum being mounted on an upstream end of the silencer. Clamping members made of iron or steel including female or male screws are secured to the end plate. An exhaust pipe is provided with a mounting seat at a fixed position thereof. The silencer can be secured to the mounting seat by means of the clamping members and bolts or nuts made of iron or steel. The end cap can be welded to a part of the outer sleeve.

Abstract: A silencer is comprised of an outer sleeve, an inner sleeve having a number of pores, and sound absorbing material including heat-resistant fibers packed between the outer sleeve and the inner sleeve. The sound absorbing material is wound directly around the outside of inner sleeve with two or more turns so that the thickness of wound sound absorbing material around the inner sleeve is greater than dimension of a gap between the inner sleeve and the outer sleeve to give interference between sound absorbing material and the inner and outer sleeves. The sound absorbing material with the inner sleeve is press-fitted into the outer sleeve. According to the present invention, sound absorbing material is prevented from being blown out by exhaust gas flowing through the inside of the inner sleeve so that the silencer is improved in durability.