| 摘要 |
This invention relates to a method for joining thermoplastic pipes (1) made by spiral winding a hollow profile (2) with mainly rectangular cross section. The method is characterized by the following stages: cutting the profile (2) in the end of the pipe along the inside of the side wall that is fastened to the nearest preceding wound round and with a cut (3) cutting the end of the profile in a right or obtuse angle ( alpha ), of equal size for all pipe ends to be joined together; closing the hole in the cut ends (3) of the profile, and preparing the end surfaces of the pipes along their entire peripheries; positioning two pipes (1) aligned to each other so that the cut profile ends (3) are axially offset; inserting a welding ring (5), matching with the inner and outer diameters of the pipes, between the two pipes (1); which welding ring comprises at least one loop of resistance of wire (8) covered by a thermoplastic sleeve (7); aligning the two pipes (1) with an inner root support (8) and an outer root support (9) around the seam with the welding ring (5); pressing the pipe ends together against each other; connecting the resistance wire (6) of the welding ring to a current source (12) to heat the thermoplastic material in the welding ring (5) and in the pipe ends so that the thermoplastic material melts down and forms a welding seam, cooling the welding seam; removing the root supports (8, 9) and other accessories (10, 11) from the pipe welded together, and cutting off the connecting wires (13) of the welding ring. |
