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Cutting and blanking are the initial processes in the production of most metal machinery and products. Commonly used cutting equipment includes flame cutting machine, plasma cutting machine and laser cutting machine. With the popularization of industrial automation production, these cutting machines also adopt digital control, forming the largest number of CNC cutting machines used in industrial production at present, of which CNC plasma cutting machines are the most popular, and the advantages of precision cutting are used in various thin-walled Material. In order to help you better understand and use the CNC plasma cutting machine, the following is a summary of the general parameters, equipment and precautions of the CNC plasma cutting machine for your reference.
First, the working principle of plasma cutting
Plasma cutting is to heat the gas to a very high temperature, make it highly ionized to form plasma, through it The arc power is transferred to the workpiece, and the high heat melts and blows the workpiece away, forming a working state of plasma arc cutting. The momentum of the high-speed plasma is used to eliminate the molten metal and form a cutting method.
Second, plasma cutting workflow
1. After the compressed air enters the cutting torch, it is distributed by the gas chamber to form plasma gas and auxiliary gas. The plasma gas arc melts the metal, while the auxiliary gas cools the parts of the torch and blows off the molten metal.
2. Electrical principle: The main circuit consists of a contactor, a high-leakage reactance three-phase power transformer, a three-phase bridge rectifier, a high-frequency arc coil and protection components. The control circuit completes the entire cutting process through the button switch on the cutting torch: pre-venting-main circuit power-high-frequency arc strike-cutting process-arc stop.
3. The power supply of the main circuit is controlled by the contactor, the air flow is controlled by the solenoid valve, and the high-frequency oscillator is controlled by the control circuit to ignite the arc and stop the high-frequency operation after the arc is established.
3. General parameters of CNC plasma cutting
CNC plasma cutting is mainly used for thin-walled materials with high precision, so the parameters of the equipment will be Directly affect the cutting quality, so the operator needs to strictly control the parameters in the cutting process design and programming
1. No-load voltage and arc column voltage
The plasma cutting power supply must be sufficiently high No load voltage, so that the arc can be started easily and the plasma arc can burn stably. The no-load voltage is generally 120-600v, and the arc column voltage is generally half of the no-load voltage. Increasing the arc column voltage can significantly increase the power of the plasma arc, thereby increasing the cutting speed and cutting thicker metal plates. The arc column voltage cannot usually be achieved by adjusting the air flow and increasing the electrode contraction, but the arc column voltage should not exceed 65% of the no-load voltage, otherwise the plasma arc will be unstable.
2. Cutting current
Increase the cutting current can also increase the power of the plasma arc, but the allowable current is limited, otherwise the plasma arc column will become thicker, the slit width will increase, and the electrode The life span is shortened.
3. Gas flow rate
Improving the gas flow rate can not only increase the arc column voltage, but also enhance the compression effect of the arc column, so that the plasma arc energy is more concentrated and the jet force is stronger, thereby Improve cutting speed and quality. However, if the gas flow is too large, the arc column will become shorter, the heat loss will increase, and the cutting ability will be weakened until the cutting process cannot be performed normally.
4. Electrode shrinkage
The so-called shrinkage refers to the distance between the electrode and the end surface of the cutting nozzle. A proper distance can make the arc be well compressed in the cutting nozzle, and obtain a plasma arc with concentrated energy and high temperature for effective cutting. If the distance is too large or too small, the electrode will burn severely, the cutting nozzle will burn out, and the cutting ability will be reduced. The shrinkage rate is generally 8-11mm.
5. Cutting nozzle height
The height of the cutting nozzle refers to the distance between the end surface of the cutting nozzle and the surface of the workpiece to be cut. The distance is generally 4-10 mm. It is the same as the electrode contraction, and the distance should be appropriate to give full play to the cutting efficiency of the plasma arc, otherwise the cutting efficiency and cutting quality will decrease or the cutting nozzle will burn out.
6. 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. The high temperature and high energy of the plasma arc determine the cutting speed, so the above The factor is related to the cutting speed. On the premise of ensuring the cutting quality, the cutting speed should be increased as much as possible. This not only improves productivity, but also reduces the deformation of the cut part and the heat-affected area of u200bu200bthe grooved area. If the cutting speed is not appropriate, the effect is just the opposite, which will increase slag sticking and reduce the cutting quality.
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