The connection surface of butt joint should be a plane. After heating two identical connecting surfaces to viscous state with a heating plate, remove the hot plate, apply a certain pressure to the connecting surfaces, and cool and solidify in the pressure state to form a firm connection. Before heating, it is necessary to mill the two surfaces of the pipeline to be welded, so as to make the surface smoother and to remove the plastic oxide layer on the surface to make the molecules melt more thoroughly.
Heating plate and milling cutter are necessary in both manual butt welding machine and hydraulic butt welding machine. The difference is that the former relies on manual operation, while the latter is powered by hydraulic system to realize semi-automatic control, especially for large diameter pipes, which require great pressure when milling, heating and cooling. It is generally difficult for manpower to achieve.
Step 1: Preparation
Prepare PE butt welding machine, including hydraulic station, milling cutter, heating plate and other related power supplies, and place the butt frame stably.
Step 2: Placement
Place two PE pipes to be welded in the butt frame. The connecting position is in the middle of the four clamps of the butt frame.
Step 3: Fixing
Close the upper and lower brackets of the butt frame, and fix the PE pipe with bolts.
Step 4: Milling
Take the milling cutter out of the basket, place it between the two PE pipes, push the control lever of the hydraulic station, and contact the two PE pipes with the milling cutter until the two connecting planes are milled well. Continuous long strip chips will be milled out.
Step 5: Alignment
Because the fixed pipe may be offset in the milling process, it is necessary to align again and adjust the misalignment amount. Be careful not to pollute the surface, otherwise it must be cut again.
Step 6: Heating
Put the milling cutter back into the basket, take the heating plate out of the basket and put it between the two PE pipes for heating. After the two pipes start to flanging and meet the requirements, put the heating plate back.
Step 7: Welding
After taking out the heating plate, connect the two PE pipes immediately with pressure and immediately close the ends of PE to be welded.
Step 8: Cooling
After the butt joint is completed, there will be a pressure holding and cooling time. At last, when the cooling time is up and the joint temperature lowers to ambient temperature, the pressure can be reduced to 0 and the welded pipe can be removed. The whole welding is finished until here.
In the whole welding process, the difficulties lie in the control of heating temperature, heating time, cooling time, milling pressure, heating and cooling pressure, etc. But don't worry. The control equipment of our hydraulic butt welding machine is equipped with thermometers, pressure gauges and timers, which can display various parameter data in real time. Detailed tutorials and data indexes will be provided in the user manual and product instruction accompanying the product, so as to facilitate you to achieve good welding effect when you use it yourself.
It can be seen that the main processes of the whole welding process consists of adjustment, heating, switching, joint pressing and cooling. When butting, the materials in viscous state on the surface can flow and diffuse. Excessive flow is not conducive to diffusion and entanglement, so it is necessary to limit the flow to a certain extent and achieve "post-fusion welding" in the limited flow. Therefore, the key of the welding process is to adjust three parameters in the welding process, which are temperature, time and pressure. In order to realize reliable welding, it is necessary to consider the properties, stress conditions, geometric shapes and environmental conditions of the connecting surface materials together. According to the general rules and the characteristics of the materials, evaluate the welding quality. After reaching the system standard, determine the process procedures of various varieties and specifications, and carry out the production and on-site installation of welded pipe fittings according to the specified process parameters, methods and steps.