The application of PLC in the industrial control machine of the AC welding machine

In industrial production, AC spot welding machines are widely used in aviation, automobiles, boilers, subways, vehicles, measuring tools, radio devices and other fields. At present, the power frequency AC spot welding machine is widely used, but the efficiency of the ordinary power frequency AC spot welding machine is very low. The use of three-phase low frequency or secondary rectification can improve the efficiency of the spot welding machine. When the secondary rectifier spot welding machine is used, the working state of the spot welding machine is low voltage and high current, especially the current can reach tens of thousands of amperes. If the control performance of the spot welding machine controller is unstable, it is very likely to burn the workpiece, or even damage the equipment, so it is very necessary to enhance the reliability of the control system. At present, the control of spot welding machine is mostly controlled by a single chip

microprocessor, but the singlechip microprocessor is easily interfered, and the working environment of the spot welding machine is relatively harsh (large temperature difference, dust, power supply voltage fluctuation, etc.) ), which makes the performance of the AC spot welder controller unstable.

At present, PLC is widely used in industrial control machines. With its excellent technical indicators and excellent adaptability to harsh environments, PLC has been universally welcomed by the industry. Using PLC to control the AC spot welder can greatly improve the reliability of the system. The welding procedure of the AC spot welding machine can only be run after pressing the two start buttons with both hands, and the welding procedure cannot be started by pressing only one of the start buttons. The welding procedure block diagram is shown in Figure 4. In this way, it can avoid accidentally pressing a start button to cause the machine to perform a wrong action, damaging the workpiece or damaging the equipment, or even personal injury. As long as the program has not entered the welding cycle, the welding program will be stopped as soon as one or two buttons are released, and the welding torch will be lifted, but if the program has entered the welding cycle, the smooth progress of the welding should be ensured, even if the start button is released, it cannot be prevented The welding process ensures that a certain pressure is maintained during the welding process. If the pressure is insufficient during the discharge process, the conductive block and the top plate are in poor contact, which is very likely to damage the conductive block and the top plate.