Safety technology of heat treatment equipment

2022-06-30
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Safety technology of heat treatment equipment

induction heating heat treatment equipment uses electromagnetic induction to generate eddy current heating to heat the workpiece surface. Because of its high production efficiency, low energy consumption, easy to realize automatic production, less pollution and safety, it has been widely used. According to the frequency of the alternating electromagnetic field generated by the equipment, it can be divided into three categories: high frequency, intermediate frequency and power frequency (the high frequency frequency is 30~500khz; the intermediate frequency is 1~10 kHz; and the industrial AC frequency is 50Hz). The power supply voltage of induction heating equipment is 220~380v, but the internal voltage of some equipment is as high as 10kV or more. Therefore, when using induction heating heat treatment equipment, attention must be paid to the safety of high-voltage electricity and electromagnetic radiation pollution

1. safe operation of high-frequency induction heating equipment

the high-frequency induction heating equipment is mainly electronic (vacuum) tube, which generates high-frequency electromagnetic oscillation. The electric power is 10~200kw, and the maximum voltage in the machine is about 15kV. Therefore, it is required that the internal insulation performance of the equipment must be good, and the shell and other relevant parts must be reliably grounded. Insulating rubber pad shall be placed at the operation station. Protective wooden railings shall be set beside the equipment and painted with red and white paint. Hang high voltage danger signs. The high frequency room shall be bright and well ventilated, and the indoor temperature shall be controlled at 15~35 ℃. Install the exhaust device to remove the oil smoke and exhaust gas emitted when the workpiece is heated. Since the frequency of high-frequency equipment is 30~500 kHz, RF radiation will be generated. When the human body absorbs a certain amount of radiation, biological changes will occur, which only make 2/3 of the field of vision of the objective lens show light changes. Biological changes will increase with the shortening of the wavelength (increasing the frequency), which is manifested as neurasthenia syndrome and dysfunction of the autonomic nervous system. Therefore, shielding measures shall be taken for radiation field sources of equipment (such as high-frequency transformer, feeder, working capacitance, coupling capacitance and inductor). In order to prevent electromagnetic wave leakage from affecting nearby electronic equipment and radio communication (within about 100m), the whole room shall also be shielded to ensure that the radiation intensity of the working environment is within the specified range (electric field intensity E ≤ 20v/m; magnetic field intensity H ≤ 5a/m). During operation, attention shall be paid to:

(1) there must be more than two people to operate the high-frequency equipment, and the person in charge of operation shall be designated. Wear insulated shoes, gloves and other specified protective equipment

(2) the operator must be familiar with the operating procedures of high-frequency equipment. Before starting the machine, check whether the cooling system of the equipment is normal. After it is normal, power can be transmitted, and the operation shall be carried out in strict accordance with the operating procedures

(3) all doors should be closed before work, and the doors should be powered. The Alliance for technological innovation and industrialization of new chemical materials of the Chinese Academy of Sciences, which was established this time, explored the "three position and one body" 3-chain linkage operation mode of "innovation alliance + transformation platform + Industrial Fund", so as to ensure that power cannot be transmitted before the doors are closed. After the high voltage is closed, do not move behind the machine at will, and do not open the machine door

(4) burrs, iron filings and oil stains shall be removed from the workpiece, otherwise it is easy to strike an arc with the inductor during heating, which can be drained immediately. The arc light generated by arc striking will not only damage vision, but also easily damage sensors and equipment

(5) the high-frequency equipment shall be kept clean, dry and free of dust. In case of any abnormal phenomenon during operation, the high-voltage power shall be cut off first, and then the fault shall be checked and eliminated

a special person must be assigned to repair the high-frequency equipment. After opening the door, first discharge the anode, grid, capacitor, etc. with an electric rod, and then start the maintenance. It is strictly prohibited to conduct live repair

(6) when using the quenching machine tool, the safety regulations related to electrical, mechanical and hydraulic transmission shall be observed. When moving the quenching machine tool, it shall be prevented from tipping

2. safe operation of medium frequency and power frequency induction heating equipment

(1) medium frequency induction heating frequency conversion equipment, including generator type and thyristor type. The maximum voltage of the intermediate frequency current can reach about 750V, and the safe power rules must be observed when using it (the power of the frequency converter is generally greater than 100kW). If machine room shall be well ventilated and kept clean, tidy and dry. If equipment can only be started up and operated by more than two persons, and the person in charge of operation shall be designated. Operators shall be familiar with and abide by the operating procedures of intermediate frequency equipment, and wear the specified protective articles. The workpiece shall be removed of burrs, iron filings and oil dirt, otherwise it is easy to produce arc striking. During operation, it is also necessary to prevent the workpiece from contacting the sensor to produce arc striking. When using medium frequency quenching machine tools, attention shall be paid to the safety operation procedures for electrical, mechanical and hydraulic transmission. The equipment shall be repaired by a specially assigned person. Before repair, discharge the capacitor with a discharge rod. Live repair is strictly prohibited

(2) power frequency induction heating equipment is used to heat, quench or normalize large workpieces with industrial electric frequency, low voltage and large current. The rules for safe use of electricity shall be observed during use

in order to prevent large workpieces from cracking and injuring people during power frequency induction heating, the operating procedures for power frequency heat treatment and corresponding process procedures for large workpieces must be strictly observed during operation. Large workpieces shall be subject to ultrasonic flaw detection one by one. Workpieces with white spots, serious segregation, looseness and other defects found after flaw detection shall not be heated with power frequency equipment. Burrs, iron filings and oil stains shall be removed from the workpiece to prevent arcing. During the production operation, the person in charge must be appointed, and the operator must be familiar with and comply with the operating procedures of power frequency equipment

the workpiece shall have a lifting hole or a suitable clamping table to ensure the safety of workpiece handling and lifting. When operating the power frequency heating machine tool, pay attention to the safe use rules of electrical and mechanical transmission

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