Electric arc instability fault of the hottest plas

Unstable fault of plasma cutting electromechanical arc

the stability of plasma cutting electromechanical arc directly affects the cutting quality. The unstable phenomenon of plasma arc will lead to defects such as uneven incision and tumor accumulation, and also reduce the service life of relevant components of the control system, and frequent replacement of nozzles and electrodes. In view of this phenomenon, this paper analyzes and puts forward solutions

1. The air pressure is too low

when the plasma cutting machine is working, if the working air pressure is far lower than the air pressure required by the manual, it means that the oil output from the oil return pipe of the equidistant oil delivery valve is large, the ejection speed of the sub arc is weakened, and the input air flow is less than the specified value. At this time, a high-energy and high-speed plasma arc cannot be formed, resulting in poor cutting quality, impermeable cutting and tumor accumulation. The reasons for insufficient air pressure are: insufficient input air from the air compressor, low pressure regulation of the air regulating valve of the cutting machine, oil contamination in the solenoid valve, blocked air path, etc

to solve the problem that the ball screw has almost no self-locking property, while the trapezoidal screw has a fixed self-locking property, the method is to observe the output pressure display of the air compressor before use. If it does not meet the requirements, the pressure can be adjusted or the air compressor can be overhauled. If the input air pressure has reached the requirements, check whether the adjustment of the air filtration pressure reducing valve is correct and whether the gauge pressure display can meet the cutting requirements. Otherwise, the air filter pressure reducing valve should be maintained daily to ensure that the input air is dry and free of oil. If the input air quality is poor, oil contamination will be generated in the solenoid valve, the valve core will be difficult to open, and the valve port will not be fully opened. In addition, the air pressure of the cutting torch nozzle is too low, and the solenoid valve needs to be replaced; If the cross section of the gas path becomes smaller, the air pressure will also be too low. The air pipe can be replaced according to the requirements of the manual

2. The air pressure is too high

if the input air pressure is far more than 0.45MPa, the excessive air flow will blow away the concentrated arc column after the formation of the plasma arc, dispersing the energy of the arc column and weakening the cutting strength of the plasma arc. The causes of high air pressure are: improper input air regulation, excessive regulation of air filtration pressure reducing valve or failure of air filtration pressure reducing valve

the solution is to check whether the pressure of the air compressor is adjusted properly, and whether the pressure of the air compressor and the air filter pressure reducing valve are misadjusted. After startup, if the regulating switch of the air filtration pressure reducing valve is rotated and the gauge pressure does not change, it indicates that the air filtration pressure reducing valve is out of order and needs to be replaced

3. The cutting torch nozzle and electrode are burned

due to the improper installation of the nozzle, such as the screw thread is not tightened, the gears of the equipment are adjusted improperly, and the cutting torch that needs water cooling is not connected with the flowing cooling water as required and the frequent arcing, the nozzle will be damaged prematurely

the solution is to correctly adjust the gears of the equipment according to the technical requirements of cutting workpiece, check whether the cutting torch nozzle is firmly installed, and the nozzle that needs cooling water should circulate the cooling water in advance. When cutting, adjust the distance between the cutting torch and the workpiece according to the thickness of the workpiece

4. The input AC voltage is too low

the use site of plasma cutting machine has large power facilities, and the failure of main circuit components in the cutting machine will make the input AC voltage too low

the solution is to check whether the power connected to the plasma cutting machine has sufficient carrying capacity and whether the specification of the power line meets the requirements. The installation site of plasma cutting machine should be far away from large electrical equipment and places with frequent electrical interference. In the process of use, the dust in the cutting machine and the dirt on the components should be cleaned regularly, and the wires should be checked for aging, etc

5. Poor contact between ground wire and workpiece

grounding is an essential preparation before cutting. Failure to use special grounding tools for actively connecting with world enterprises, insulation on the surface of the workpiece and long-term use of aging ground wires will cause poor contact between the ground wire and the workpiece

special grounding tools should be used, and check whether there is insulation that affects the contact between the ground wire and the workpiece surface, so as to avoid using aging grounding wires

6. When the plasma cutting machine is working, it is necessary to ignite the plasma arc first. The gas between the electrode and the inner wall of the nozzle is excited by the high-frequency oscillator to generate high-frequency discharge, which makes the gas locally ionized to form a small arc. This small arc is ejected from the nozzle by compressed air to ignite the equidistant arc, which is the main task of the spark generator. Under normal circumstances, the working time of the spark generator is only 0.5 ~ 1s, and the reason why it cannot automatically break the arc is generally that the components of the control circuit board are misadjusted, and the discharge electrode gap of the spark generator is inappropriate

the discharge electrode of the spark generator should be checked frequently to keep its surface flat, and the discharge electrode gap of the spark generator (0.8 ~ 1.2mm) should be adjusted in time. If necessary, replace the control board

7. Other

in addition to the above reasons, the cutting speed is too slow, the perpendicularity of the cutting torch and the workpiece during cutting, as well as the operator's familiarity with the plasma cutting machine, the operation level, etc., all affect the stability of the arc of equidistant concentrated pneumatic coordination to solve key problems. Users should pay attention to these aspects