Positioning and setting of arc pressure regulator of NC plasma cutting machine and handling of common arc break fault

The gantry numerical control NC plasma cutting machine is higher than the manual cutting machine, and the fault maintenance involves the circuit, control system, drive and other aspects.Once the plasma cutting machine malfunction user service, equipment manufacturers are generally not immediately sent a maintenance personnel, in order not to delay processing progress, for the simple fault, users can find and solve on their own, to use the arc pressure controller block to automatically adjust the cutting height to make the numerical control system for cutting mode is set to cutting machine mode and then start the arc pressure block power supply.

The first step is to test whether the manual increase is normal.Press the manual up and down buttons on the height adjuster of the gantry CNC plasma cutting machine to observe whether the movement of the cutting gun is correct;When the cutting torch reaches the upper limit, press the manual rising button. At this time, the cutting torch shall not rise, but press the falling button to lower the cutting torch.Press the manual descent button at the point where the cutting torch reaches the lower limit. At this time, the cutting torch shall not descend. Press the ascending button again, and the cutting torch shall rise.If the torch cannot go up or down, first check to see if the torch is in the upper and lower positions.If the limit switch is found to be faulty, it should be replaced in time, otherwise the motor will be damaged due to the switch fault.

The second step is initial positioning test.Press the initial positioning button on the elevator of the gantry numerical control plasma cutting machine. At this time, the plasma cutting torch should move downward at the set speed. After the cutting nozzle contacts the steel plate, it stops and then rises at the set speed, and stops at the appropriate starting height.Arcing height is usually 1.5~2 times of the cutting height. Users can adjust the positioning time to change the arcing height according to actual cutting experience, so as to achieve the best cutting quality under the premise of reducing the damage of consumable materials.

Step 3: Arc voltage test.Press the initial positioning button on the elevator of the gantry CNC plasma cutting machine to make the cutting torch reach the starting height.Press the arc pressure test button on the hightener, and the arc is started successfully. Watch the real-time arc pressure monitored in the arc pressure monitoring window, and the displayed value should be close to the set value of the arc pressure.If the difference between the two is too large, please adjust the arc pressure set value, so that it is similar, otherwise, it will cause cutting height is too high or the cutting torch dragging on the steel plate, both ways, will lead to cutting quality decline, and cause serious damage to the cutting torch supplies.

However, there is another problem is also followed, our after-sales staff in the process of dealing with customers for a long time will respond to the gantry CNC plasma cutting machine running well under the circumstances of suddenly broken arc.What kind of situation is this?The following will give you a specific analysis;

In fact, this situation has little to do with the equipment itself, and customers do not need to worry blindly when they encounter such problems.According to our analysis, there are generally the following four situations:

1, the air pressure is insufficient or the air flow is too small;When plasma cutting, the flow of air compressor should be guaranteed. Some customers tend to ignore this detail.At this time only need to adjust the pressure, replace the large pipe or air compressor can be;

2, perforation time is too long;Setting the perforation time is too long is also a possibility of this fault, the corresponding adjustment (reduce) perforation delay, and in many cases, it is not necessary to set the perforation delay.

3. The height of the cutting nozzle from the steel plate is too large;We know that a big factor of the gantry CNC plasma cutting machine arc is the height of the cutting mouth from the plate. In a few cases, it may have arc, but in fact it is too reluctant, so it caused the sudden arc breaking phenomenon in the process of cutting;

4. Arc voltage regulator fails.The role of arc voltage regulator is to adjust the height of the plate and the cutting mouth, to maintain a stable balance value;The gantry numerical control plasma cutting machine is not a big problem when cutting the flat plate, but for the uneven plate arc pressure automatic problem, it is easy to go wrong.At this time you can first check the arc pressure line measurement with multimeter DC500V file (generally DC60-200V).

About the plasma CNC cutting machine speed and thermal deformation detail

About the plasma CNC cutting machine speed and thermal deformation details:

Usually the plasma cutting power supply, must have high enough no-load voltage, in order to easy arc ignition and make the plasma cutting machine arc stable combustion.The no-load voltage is generally 120-600V, and the arc column voltage is generally half of the no-load voltage.Increasing the voltage of the arc column can obviously increase the power of the plasma arc, so it can improve the cutting speed and the cutting thickness of the metal plate.The arc column voltage is often not reached by adjusting the gas flow rate and increasing the electrode shrinkage, but the arc column voltage can not exceed 65% of the no-load voltage, otherwise the plasma arc will be unstable.

①. Height of cutting mouth

The height of the cutting mouth refers to the distance between the end face of the cutting mouth and the surface of the workpiece to be cut.The distance is generally 4~10mm.It is the same as the electrode shrinkage, the distance should be appropriate to give full play to the cutting efficiency of the plasma arc, otherwise it will reduce the cutting efficiency and cutting quality or make the cutting nozzle burn out.

②. Gas flow rate

Increasing the gas flow rate can not only improve the arc column voltage, but also enhance the compression effect on the arc column, so that the plasma arc energy is more concentrated and the jet force is stronger, so that the cutting speed and quality can be improved.But the gas flow is too large, but will make the arc column shorter, increase the heat loss, so that the cutting ability is weakened, until the cutting process can not be carried out normally.

③ cutting speed

The above factors directly affect the compression effect of the plasma arc, that is, the temperature and energy density of the plasma arc, and the high temperature and high energy of the plasma arc determine the cutting speed, so the above factors are related to the cutting speed.Under the premise of ensuring the cutting quality, the cutting speed should be improved as far as possible.This not only improves productivity, but also reduces the amount of deformation of the cut parts and the heat-affected area in the slit area.If the cutting speed is not appropriate, the effect is opposite, and it will increase the viscosity of slag, cutting quality decline.

④ cutting current

Increasing the cutting current can also increase the power of the plasma arc, but it is limited by the maximum allowable current. Otherwise, the plasma arc column will become thicker, the slit width will increase, and the electrode life will decrease.

⑤. Internal shrinkage of electrode

The so-called shrinkage refers to the distance between the electrode and the end face of the cutting nozzles. The appropriate distance can make the arc compress well in the cutting nozzles and obtain the plasma arc with energy concentration and high temperature for effective cutting.If the distance is too large or too small, the electrode will be seriously burned, the cutting nozzle will be burned out and the cutting ability will be reduced.The inner shrinkage is generally 8-11mm.