| 摘要 |
PURPOSE: A non-welding rectangular pipe whose manufacturing process and manufacturing cost are simple and inexpensive respectively by simply insert coupling the upper and lower elements after manufacturing upper and lower elements from a steel sheet without welding, and a manufacturing method thereof are provided. CONSTITUTION: The non-welding rectangular pipe comprises an upper element(102) the lower part of which is formed in an open rectangular shape, and which comprises an inner projection(106) formed by bending both sides of the steel sheet unidirectionally to a certain angle as continuously unwinding a steel sheet provided in the state that the steel sheet is wound in a roll shape and bending the free end part of both sides of the steel sheet inwardly in an acute angle; and a lower element(104) comprising first corner(58) formed by bending both sides of the steel sheet unidirectionally to a certain angle as continuously unwinding the steel sheet provided in the state that the steel sheet is wound in a roll shape, second corner(59) formed by smoothly bending the free end part of both sides of the steel sheet outwardly in an acute angle, and an outer projection(108) projected to the outer part of the second corner(59), wherein the inner projection(106) of the upper element(102) is insert coupled between an extension part of the first and second corners(58,59) of the lower element(104) and the outer projection(108).
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