| 摘要 |
PURPOSE: To obtain a structure excellent in both of joining strength and hermetical sealability by allowing the interior of a pipe part to communicate with the interior of a molded product main body through the engaging part embedded in the molded product main body at the time of blow molding. CONSTITUTION: A pipe part 14 is allowed to pierce through the closing wall 20 of a pipe-shaped insert and the part of a main pipe 10. By this processing, the interior of the pipe part 14 of a branch pipe 12 is allowed to communicate with the interior of the pipe 10 through an engaging part 16. In this constitution, the pipe 10 is shrunk after blow molding. Since the inner peripheral surface 22 of the engaging part 16 of the pipe 12 is formed into a taper shape over the entire periphery thereof so as to be reduced in diameter toward the interior of the pipe 10, the pipe 10 is molded and shrunk so as to press the inner peripheral surface 22 so that the inner peripheral surface 22 and the pipe 10 are strongly joined and the hermetical sealability between them is increased. No gas is generated between the inner peripheral surface 22 and the pipe 10 by molding shrinkage. This molding shrinkage is positively utilized to ensure the excellent joining strength and hermetical sealability of the pipes 12, 10. |
