| 摘要 |
PURPOSE:To enable a branch tube to be joined to a main tube efficiently with a very small occurence of defects by using a burner having plural burner holes arranged in ring-like form. CONSTITUTION:After the end openings of a main tube 1 are sealed with spongy rubbers 2, a burner 100 is located over a part of the main tube 1 in which a hole is to be formed and to which a branch tube is to be joined, then a concentrated combustion gas current 111 is applied to the above part to heat and soften the main tube 1 locally. Next, the inner surface of the main tube 1 is pressed by N2 gas or the like so as to break the locally heated part of the main tube 1 thereby forming a hole (B'). Following that, the periphery of the hole (B') is heated and soften by the combustion gas of the burner 100. At the same time, the branch tube 5 is sent along the center line (X-X') of the burner 100 until the lower end 5 of the branch tube 5 is located at the concentrated combustion gas current 111, and the lower end of the branch tube 5 is heated and soften. After that, at the point when the periphery of the hole (B') and the lower end of the branch tube 5 are sufficiently heated and soften, the lower end of the branch tube 5 is brought into contact with the hole (B') thereby fusing the tube 5 to the hole (B'). |
