1. Butt welding process According to the working principle of the butt welding machine, the butt welding process can be divided into two types: resistance butt welding and flash butt welding:
Resistance welding is done to cut the ends of the steel bars to the plastic state, then cut off the power, then heat to the plastic connections. This welding process is easy to produce oxidation and cinder joint site, and the required part of the steel bar should be smooth and smooth, and the energy consumption during welding is very high, so the welding machine has a high power, so it is rarely used.
Flash butt welding is a process in which molten metal particles during welding create sparks (flashes) during welding. While the molten metal is blown out, the oxides and slag can be brought out, making the welded joints of good quality and widely used, especially in the connection between mild steel and low alloy steel.
2. The following matters should be noted:
Adjust the distance between the jaws. When the control screw is at the left limit, the distance between the two welded parts is the difference in length and extrusion. When the joystick is at the proper limit, the distance between the clamps should be the length of the two welded parts and 2~3mm, the position before welding.
Adjust the short-circuit limit switch so that the power supply automatically cuts off the power supply when the welding is completed (the predetermined squeeze is reached).
According to the shape of the workpiece to be welded, adjust the jaws to clamp the two jaws at the same level, and then clamp the welded parts.
In order to prevent the welding parts from overheating instantaneously, the adjustment series should be added during the test welding, and the appropriate secondary voltage should be selected. In flash butt welding, a higher secondary voltage is used.
To avoid overheating of welding, the cooling water valve must be opened before welding. For the convenience of inspection, a funnel is provided on the left side of the welding machine to directly observe the flow to check whether there is cooling water flow inside the welding machine.
3. The key parts of the steel bar of the welding machine
Welders must undergo professional training, be familiar with the construction, performance, and operating procedures of the welding machine, and master the selection of process parameters, quality inspection specifications and other knowledge.
The machine should check whether the machine is sensitive and reliable, whether the electrical system is safe, whether the cooling water pump system is leaking, and whether the lubricating parts are well lubricated.
Reinforcement with diameter welding is strictly prohibited. Major reinforcement must be welded before welding. In order to ensure the quality of the welding, it is necessary to perform cleaning, descaling and correction at the felt end of about 150 mm.
During operation, you must wear tinted glasses and protective caps to avoid eye and metal irritation.
The butt welding machine should be parked in a clean, dry and ventilated place, and the butt welding machine should be equipped with waterproof, moisture-proof, anti-foam, and fire-fighting equipment, and flammable items should not be stacked within the welding range.
The welding machine should be equipped with a special wiring switch and installed in the switch box, and the capacity of the fuse should be 1.5 times that of this machine. The welding machine enclosure must be well grounded.
After the welding appearance inspection, the steel bar should be properly thickened, and the surface should be free of cracks and obvious burns. The crankshaft of the joint shaft shall not exceed 6°, the cheap steel shall not exceed 1/10 of the diameter of the steel bar, and shall not be larger than 2 mm.
After the work is completed, the ground is cleaned, the fire is destroyed, and the air is compressed in winter, so that the water in the cooling pipeline is blown away, and the power is cut off.
