Method of connecting two elongated portions of metallic plate, method of manufacturing exhaust pipe of two-passage construction, and exhaust pipe of two-passage construction

A method of manufacturing an exhaust pipe of two-passage construction, comprising the steps of:

• preparing a metallic plate having a first end and a second end respectively elongated in a longitudinal direction of the exhaust pipe;
• bending the metallic plate into a substantially S shape in cross section having 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 said partition plate;
• providing a target elongated along said groove in a manner to extend substantially radially outward from said closed end;
• and
• generating a welding arc between said target and a welding gun disposed on a side of said open end such that said substantially closed end and said target are welded together.

A method of manufacturing an exhaust pipe of two-passage construction, comprising the steps of:

• a) bending two longitudinally elongated metallic plates respectively into substantially semicircles with longitudinally elongated sides being further bent radially inward to thereby form inwardly inclined end portions;
• b) assembling the semicircles obtained in step a) together such that said inclined end portions of one semicircle face corresponding inclined end portions of the other semicircle to thereby form a substantially circular semi-product, said semi-product having on each diametrically opposite sides thereof a groove of substantially V shape in cross section with a substantially closed end on a radially inner side and an open end on a radially outer side;
• c) interposing a diametrically extending central partition plate along said grooves in a manner to extend diametrically outward from said closed ends, whereby a target is formed by a portion extended beyond each of said closed ends;
• and
• d) generating a welding arc between said target and a welding gun disposed on a side of said open end such that said substantially closed end and said target are welded together.

An exhaust pipe of two-passage construction comprising:

• a central partition plate extending in a diametrical direction and in a longitudinal direction throughout the exhaust pipe;
• a substantially semicircular peripheral wall on each lateral side of said partition plate so as to extend in the longitudinal direction of said partition plate, said partition plate and each of said peripheral walls jointly forming at each of radially outer portions of said partition plate a groove of substantially V shape in cross section having a substantially closed end on a radially inner side and an open end on the radially outer side;
• and
• a target elongated along said groove in a manner to extend substantially radially outward from said substantially closed end of said groove, said target being adapted to be integrally welded with the radially inner side of said groove.

An exhaust pipe of two-passage construction comprising:

• a central partition plate extending in a diametrical direction and in a longitudinal direction throughout the exhaust pipe;
• a substantially semicircular wall formed on each lateral side of said partition plate so as to extend in the longitudinal direction of said partition plate;
• and
• a groove of substantially V shape in cross section formed on each diametrically outer end portion of said partition plate, said groove having a welded portion between said partition plate and a diametrically inner end of said groove,
• wherein said welded portion lies radially inward of an imaginary line of an inner circumference of said semicircular wall.