| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to safely execute the tube bending operation without impairing the quality of a tube by so expanding a pressurizing bag as to be smaller than the diameter of the thermoplastic tube, winding the outer periphery with a heating sheet, then inserting it to the part desired to be bent in the tube, further expanding the bag, and heating the sheet. SOLUTION: A pressurizing bag 1 is coupled to a coupling tube 2, and the bag l is expanded by an air pump 3. In this case, the diameter of the bag 1 is reduced smaller than the inner diameter of the thermoplastic tube, and the bag 1 becomes cylindrical even through it is slender. Its outer periphery is loosely wound at the side that the heat insulator of a heating sheet 4 is disposed as the inside. Then, it is inserted to the part desired to be bent in the tube. In this case, when the bag 1 has a mandrel and a locking plate, if it is intruded by using an inserting rod, it is facilitated. Thereafter, the bag 1 is further expanded until the sheet 4 is brought into contact with the inner periphery 5 of the tube. After the close contact, the sheet 4 is heated. |
