1. Material preparation Pipes and fittings should be matched with equal diameters, reducing elbows and tees according to the construction requirements. Hot-melt welding should use pipe fittings of the same grade and material. Welding between pipe fittings of different grades and materials with similar performance should be tested first.
2. Clamp the pipe Use a clean cloth to remove dirt from the ends of the two tubes. Place the pipe in the rack slips, replace the basic fixture according to the pipe fittings to be welded, and select the appropriate slips so that the lengths of the two ends of the butt joint are approximately equal and should be as short as possible while meeting the requirements of milling and heating . The part of the pipe outside the frame is held up with a support frame, so that the axis of the pipe is at the same height as the center line of the frame, and then fastened with slips.
3. Cutting Insert the milling cutter, then slowly close the welding ends of the two pipes, and apply appropriate pressure until continuous chips appear on both ends. Remove the pressure, wait a moment, and then exit the movable frame. The chip thickness should be 0.5～1.0mm to ensure that the impurities and oxide layers on the end faces of the welded pipe sections are cut, and the two butt joint end faces are smooth and clean.
4. Centering The misalignment of the two pairs of welded pipe sections should be as small as possible. If the misalignment is large, it will cause stress concentration, and the misalignment should not exceed 10% of the wall thickness.
5. Heating After the temperature of the heating plate reaches the set value, put it into the rack and apply pressure until the minimum curling edge on both sides reaches the specified width and the pressure is reduced to the specified value to absorb heat. Ensure that there is enough molten material to prepare for the mutual diffusion of molecules during melting and docking.
6. Switch The period from the end of heating to the beginning of the fusion docking is the switching period. To ensure the quality of the fusion docking, the shorter the switching period, the better.
7. Fusion butt It is the key to welding. The process of melting butt joint should always be carried out under melting pressure.
8. Cooling Due to the poor thermal conductivity of plastic materials, the cooling rate is correspondingly slow. The shrinkage of the weld material and the formation of the structure proceed at a slow speed over a long period of time. Therefore, the cooling of the weld must be carried out under a certain pressure.