The degree of automation of plasma cutting machines continues to increase, and its advantages are becoming more and more prominent in production, which can greatly shorten the construction period and reduce costs. Therefore, it mainly introduces the characteristics of the plasma cutting machine, compares the plasma cutting machine and the traditional cutting machine, and discusses the operation precautions and preventive maintenance of the plasma cutting machine in combination with work practice.
The plasma cutting machine mainly uses plasma technology to cut metal materials. During the cutting process, the heat generated by the high-temperature plasma arc causes the cut position of the metal workpiece to form a local melting and evaporation. At the same time, the momentum generated by the high-speed plasma makes The molten metal is removed, and a cut is formed. According to different working gases, plasma cutting machines can be divided into argon, oxygen and air plasma arc cutting. The cutting current of plasma cutting machine generally does not exceed 100A, and the cutting thickness should be controlled within 30mm.
Comparison of plasma cutting and traditional cutting
The plasma cutting machine has a wide range of applications and can be used for almost all conductive metal plate and tube materials such as stainless steel, cast iron, aluminium, copper, titanium, nickel, and composite metals. Generally, the working process of a plasma cutting machine is as follows: the three-phase power supply is turned on, and the compressed air source is turned on, the main machine power switch and the cutting torch switch are turned on, and the main contactor is closed after the electromagnetic 0.2 s, and the three-phase rectifier transformer is energized to work, The three-phase bridge is rectified into a direct current for plasma arc generation from the cutting torch; during this time, the arc starter and the non-transfer generator are put into operation. This process is used to generate the high-frequency and high-voltage electricity required for arc ignition, and the arc ignition time It is about 0.5~1s. When the plasma arc ignition is successful, the cutting torch nozzle sprays a high-temperature and high-speed plasma arc beam. The cutting process does not need to be preheated, and the cutting effect is significantly better than that of a CNC cutting machine. Compared with traditional cutting, the plasma cutting machine does not need to be preheated, and the work efficiency is very high, while the traditional flame cutting method requires preheating in advance to melt the metal before it can operate. Moreover, traditional flame cutting takes a long time to warm up in advance, which has obvious disadvantages in work efficiency compared with plasma cutting. The deformation of the plasma cutting machine is also very small. The traditional flame cutting is achieved by heating a large area of the workpiece. The direct consequence of the large area heating is that the workpiece is deformed, which affects the overall performance and effect of the workpiece, while plasma cutting is The use of electricity to release heat can make the workpiece partially heated and turn red. The splash during operation is small and will not cause major damage to the operator. The traditional flame cutting spark splash is very large, and the release of heat energy is relatively intense, which is easy to constitute an operation The life hurts. The fuel of the traditional flame cutting method is acetylene, and oxygen is used as a combustion-supporting agent to work, which is dangerous. If a toothless saw cutting machine is used, there is no protective cover, and the operator has a greater safety hazard during the operation. On the contrary, the plasma cutting process does not use gas and only relies on heating points to work, which is very harmful. Therefore, the plasma cutting machine has unparalleled advantages in terms of work efficiency, performance and safety.
Precautions for the safe operation of the plasma cutting machine
(1) Inspect the power supply, air source, water source, etc., to confirm that there is no leakage, air leakage, or water leakage, and the working place and protective ground connection of electromechanical equipment is safe and reliable. The trolley and the workpiece are placed in the proper position so that the workpiece and the positive electrode of the cutting circuit are connected, and a slag pit is set under the cutting working surface.
(2) The nozzle diameter should be determined according to the workpiece material, type, thickness and other parameters, and the cutting power supply, gas flow and electrode shrinkage should be adjusted. The automatic cutting trolley should run empty and select a reasonable cutting speed. Cutting operators and cooperating personnel must strictly follow the operating regulations to do construction protection. Operators must wear protective masks, welding gloves, hats, filter membrane dust masks and soundproof earmuffs in advance. For workers who are not wearing protective goggles, please be careful not to look directly at the plasma arc, and do not approach the plasma arc with unprotected and bare skin. Take safety measures in advance to prevent accidents such as electric shock, falling from high altitude, gas poisoning and fire.
(3) During the cutting process, the operator should stand upwind to operate. Air can be exhausted from the lower part of the workbench, and the open area on the workbench should be reduced. During operation, if the no-load voltage is high, check the insulation of the equipment protection ground, working ground and torch handle to ensure that the workbench is well insulated from the ground. The electrical control system of the equipment is best equipped with a no-load circuit breaker. The high-frequency generator should be equipped with a shielding cover, and the high-frequency circuit should be cut off immediately after the high-frequency arc ignition is performed. The use of thorium and tungsten electrodes should comply with relevant operating regulations. The electric welding machine used at the operation site should have or be equipped with sun-proof, rain-proof and moisture-proof measures, and fire-fighting equipment should be in place and attract sufficient attention. When working at high altitudes, pay more attention to safety protection, wear seat belts, always keep safety in mind, and take precautions against fires around and below the welding and cutting areas that may ignite, and set up special personnel to supervise and prevent.
(4) When the welded workpiece is similar to a pressurized or sealed container, oil drum, pipeline and other facilities, or a workpiece that is to transmit flammable gas and solution, the pressure in the container and pipeline should be released first to remove the flammable gas and solution. And clean the pipelines with toxic and hazardous materials; if the container has residual grease, it can be rinsed with steam or alkaline water, open the lid to ensure that the container is clean, and fill it with water before welding. Welding and cutting operations in the container must take measures to prevent electric shock, and prevent poisoning and suffocation during operation. For welding and cutting operations of sealed containers, vent holes should be reserved in advance, and ventilation equipment can be installed if necessary to ensure the safety of operators; if lighting operations are required in the container, the lighting voltage should be lower than 12 V, welders and weldments The room is strictly insulated, and a special person is arranged outside the container for supervision and care. If the plastic container has been sprayed with paint, welding operations inside it are prohibited.
(5) If the pressure vessel, pipeline, and live equipment are under pressure, or there are flammable and explosive materials in the vessel, welding and cutting are strictly prohibited. On cloudy and rainy days, open welding and cutting operations are prohibited. When working in a wet and rainy place, insulation should be done in advance, and the operator should wear insulated shoes and stand on the insulating mat to perform the work. After the operation is completed, the power, air and water sources should be cut off in time to ensure safety during construction.
Preventive maintenance and repair of plasma cutting machine
1. Pay attention to the inspection during equipment operation
The wide application of CNC plasma cutting machine is the development trend of plasma cutting. CNC plasma cutting machine is more advanced, more complicated and smarter than traditional plasma cutting machine. At the same time, its maintenance and maintenance are much higher than ordinary cutting machines. According to the specific conditions of the equipment, a detailed maintenance and repair item list should be formulated, and regular equipment inspections should be done on a weekly, monthly, quarterly, and annual cycle. For example: what is the heating degree of the cabinet and the motor during the operation of the system; whether there are abnormal noises and odours during the operation; whether the readings of various pressure gauges are within the normal range; whether there is leakage in each pipeline and joint; the lubrication status of the equipment Is it good?
2. Carry out preventive fault diagnosis of the plasma system
The most important part of the CNC plasma cutting machine is the plasma system. Its quality directly affects the quality and accuracy of the cutting product, and also affects the cost control of consumables. Therefore, in daily work, the cutting gas in the plasma system Pressure and flow are very important. It is necessary to design-related tables to monitor the cutting gas flow regularly and then compares with the standard values in the plasma manual to observe whether the gas indicators of the plasma system are normal when the total inlet pressure is normal. It is normal to determine whether the plasma system of the cutting equipment is faulty. If the plasma system gas is abnormal, it is a precursor to the plasma system failure. The hidden troubles should be solved in advance to avoid burning the plasma cutting torch and body when the failure occurs, thereby reducing the cost of replacing the cutting torch and the spare parts of the body. Control the cost of consumables.