Thermal flash process: After the current is applied, th […]
Thermal flash process:
After the current is applied, the two workpieces make surface contact for many times, and then quickly separate to form intermittent flash and then turn into a stable continuous flash process until upsetting. In addition to the intermittent flash preheating formed by reciprocating movement, resistance preheating method can also be used, that is, the two workpieces contact under a certain pressure, the current passes through the contact surface of the two workpieces, and the heat generated by the resistance of the contact surface is preheated when the current is applied.
In the process of preheating, flashing and upsetting, close the power supply during welding, and then make the end faces of the two rebars alternately contact and separate. At this time, the gap between the end faces of the rebars gives out continuous flashing, forming a preheating process. When the rebars enter the flashing stage after entering the preheating temperature, they are then upsetting to complete a welding joint.
The flash speed is obtained by combining the initial speed and acceleration. During the flash process, the flow regulating valve is further opened through the roller pole, and therefore the flash speed is increased. The flash speed depends on the welding current and the material cross section area. The flash speed is adjusted too fast, and the material heating time is short.
The flash speed is adjusted by turning the right knob under the upsetting oil cylinder.
Flash speed can adjust flash acceleration by changing the angle of the bump with adjustable angle.
If the speed of the flasher is too high, the flash process will end quickly and the material will start to upset prematurely. If the acceleration speed is too low, the material cannot be fully heated.
The equipment will cause dust accumulation in the welding process, so it is necessary to clean the inside and outside after the work is completed. It is worth noting that the jaw and electrode of the fixture should be cleaned once an hour, otherwise the current intensity will not be enough during the work. Before each use, the spatter and the media on the surface should be cleaned to ensure that the contact resistance between the workpiece and the electrode remains low.
The welding slag falling into the guard plate needs to be removed immediately. If it continues to accumulate, the upsetting speed will be affected.
In the process of equipment maintenance, if a large distance needs to be opened between the moving plate and the fixed plate, the moving plate shall be returned to the bottom by manual operation and the hydraulic station shall be closed.
The guide rail bearings of the main engine are lubricated manually. All other moving joints and guide rails are equipped with automatic oil injectors to inject lubricating oil at regular intervals. 5 # oil shall be added to the oil injectors in time.
Precise control valve is set in the hydraulic system of the welding machine to realize stepless adjustment of flash butt welding speed, ensure the stability of flash process, reduce slag inclusion in the welding workpiece joint, make the metallography good, firm and beautiful.
The flash butt welding machine is mainly used for butt joint of end faces of parts. Generally, the shape and section of the butt joint end faces are the same. The butt joint materials include ordinary carbon steel, stainless steel, aluminum alloy, brass, etc.