Fault diagnosis and maintenance principle of medium frequency induction heating equipment
1. What is medium frequency induction heating equipment
The series resonance used by the intermediate frequency induction heating equipment, that is, the voltage-type resonance frequency tracking. Therefore, the efficiency is higher and the power factor is higher. Therefore, it has a significant power saving effect, heating 341 degrees per ton of bar material. The uncontrollable full-bridge rectifier at the front stage of the intermediate frequency induction heating equipment will not cause waveform distortion in the rectification section, and there is no clipping of the cut-off angle, and it is filtered by a large capacitor, so the harmonic number is small and the interference to the grid is small
2. Working principle of medium frequency induction heating equipment
The working principle of intermediate frequency induction heating equipment is to place a metal cylinder in an induction coil with alternating intermediate frequency current. The metal cylinder does not directly contact the induction coil. The temperature of the energized coil itself is very low, and the surface of the cylinder is heated to redness. , Even melting, and this redness and melting speed can be achieved only by adjusting the frequency and the strength of the current
3. Application fields of medium frequency induction heating equipment
1. Tool brazing
2. Brazing of diamond tools, grinding discs, trimming wheels, and tangent wheels
3. Heat treatment of parts
4. Precious metal smelting
5. Smelting a small amount of stainless steel materials, etc.
6. Brazing of copper pipe joints
7. Welding of the bottom of the electric kettle
8. Annealing of gears, shafts, etc.
9. Stainless steel stamping and forming
4. Fault diagnosis and maintenance of intermediate frequency induction heating equipment
For the newly purchased intermediate frequency induction heating furnace used for the first time, the cause of the failure may be: during the transportation of the intermediate frequency induction heating furnace, due to vibration and other factors, the circuit plug-in in the intermediate frequency induction heating furnace becomes loose or falls off, and the connection occurs Short circuit or open circuit, etc.; during the storage process of the intermediate frequency induction heating furnace, the components in the intermediate frequency induction heating furnace or the circuit board are damp and other factors cause component failure; due to the failure of the user to follow the operation steps of the intermediate frequency power supply In some cases, when the intermediate frequency power supply was assembled and debugged before leaving the factory, some components with quality problems could not be detected, which affected the normal operation of the intermediate frequency induction heating furnace. Whether the fault of the intermediate frequency induction heating furnace occurs on the line or on the electrical and electronic components, it is generally caused by a short circuit or open circuit. The phenomenon and the reasons are as follows.
Large short-circuit. When the circuit is partially short-circuited, the load will fail due to the short circuit. The resistance of this load circuit is small, and a great short-circuit current will be generated, which will cause the medium frequency induction heating furnace to be overloaded and the wire insulation will burn out. Fire. For example, the two wires of the device pole are directly connected; the device is directly connected without a load; the insulation of the wires is damaged and contacts each other to cause a short circuit; the loosening of the terminal screw causes the contact with the end of the wire; the two ends of the wire are accidentally touched during the wiring; The head touches the metal housing part, etc.
Open circuit fault. For an open circuit, there is no device after the circuit breakpoint, so when the device is interrupted at a certain point in the load circuit, the current does not flow. The cause of the fault is broken line, loose wire connection end, poor contact, etc.
V. Instructions for safe operation of medium frequency induction heating equipment
1. Medium frequency induction heating and variable frequency equipment, with generator type and thyristor type. The maximum voltage of the intermediate frequency current can reach about 750V, and the safe electricity rules must be observed when using it (the power of the inverter is generally greater than 100kW). The intermediate frequency equipment room should be well ventilated, clean, tidy, and dry. IF equipment must be powered on by two or more people, and the person in charge of the operation must be designated. Operators should be familiar with and abide by the IF equipment operating procedures, and wear the specified protective equipment. The workpiece should be free of burrs, iron filings and grease, otherwise it is easy to cause arcing. During operation, it is also necessary to prevent the workpiece from contacting the sensor to cause arcing. When using an intermediate frequency quenching machine tool, you should pay attention to the safe operating procedures for electrical, mechanical, and hydraulic transmission. The equipment needs to be repaired by a dedicated person. Use a discharge rod to discharge the capacitors before repairing. Emergency repairs with power on are strictly prohibited.
2. Power frequency induction heating equipment uses industrial electric frequency, low voltage and high current to heat and quench or normalize large workpieces. The rules for safe electricity use should be followed when using it.
3. In order to prevent large workpieces from blasting and injuring people during power frequency induction heating, the power frequency heat treatment operation procedures and the corresponding large parts heat treatment process regulations must be strictly followed during operation. Ultrasonic flaw detection of large workpieces should be carried out one by one. Any workpiece with white spots, serious segregation and looseness found after flaw detection, it is forbidden to use power frequency equipment to heat it. The workpiece should be free of burrs, iron filings and oil stains to prevent arcing. In the production operation, the person in charge must be designated, and the operator must be familiar with and abide by the operating procedures of industrial frequency equipment.