When the electrician repairs or modifies the machine tool line, if the safety operation specifications are not observed, the machine tool may be damaged or even personal injury may occur. Therefore, when repairing or modifying a machine tool, the following safety practices must be observed.
(1) Maintenance should be blacked out, and there must be a guardian for electrification maintenance.
The electrical maintenance of the machine tool must be carried out under the condition of power failure, and maintenance by one person is strictly prohibited. When you have to work with electricity, in addition to maintaining good insulation between the live body and the earth, the operator must also have a professional electrician to monitor and stop the unsafe behavior of the operator. At the same time, live maintenance should pay special attention to prevent short circuit. Special care must be taken to prevent short circuits when servicing or measuring terminals that are close together. Because the terminals are close together, the potential is different, and a slight care when measuring the repair will cause a short circuit accident. When the maintenance is performed, the eyes are generally close to the maintenance site. In the event of a short-circuit accident, the short-circuit spark of the splash is extremely likely to damage the eyes. In addition, short circuits can shorten or even burn out the life of some components.
(2) Maintenance personnel must be familiar with the circuit principle of machine tool electrical
Electrical maintenance of machine tools is a very practical work, advocates dare to practice, but firmly opposes blind hands. Maintenance personnel must be familiar with the basic principles of machine tool electrical.
(3) Master the general maintenance method and select components reasonably
The electrical wiring of the machine tool is simple and complicated. For the simpler electrical control circuit, since the number of electrical components and the number of wires are few, it is clear at a glance. After a fault occurs, the faulty parts can be found by sequentially checking the electrical appliances one by one and the wires one by one. However, for machines with complicated control lines, it is difficult to check the electrical faults by the above method. When a machine with a complicated control line fails, the maintenance personnel must flexibly apply various methods according to the nature and specific conditions of the fault while familiarizing with and understanding the electrical control circuit diagram of the machine tool. For example, power-off inspection uses a multimeter to measure resistance, and power-on inspection uses measurement voltage and current methods. Other methods include visual observation method, short-circuit method, etc. If necessary, cross-use various methods to quickly and effectively find faults. point. After finding the fault point, it is necessary to take correct repair methods for different fault conditions and parts. Do not easily replace the electrical components and wire replacement methods, and do not allow easy changes to the line or replace electrical components with different specifications to prevent A human error has occurred. If you need to replace the circuit components, you must make a reasonable choice. You can't save time and convenience, but you can use small generations and small ones to ensure normal circuit performance and safe and reliable operation.
(4) Inspection lighting uses safe voltage
The lighting for maintenance should use a safe voltage of 36V or less. The lamp cap should have a shield. It is strictly forbidden to use a voltage higher than 36V. Because the voltage of 36V is the safe voltage value used in the general situation specified by the state, the maintenance of the machine tool uses a voltage not higher than 36V. In case the maintenance personnel are more likely to get rid of the electric shock after the electric shock, the personal safety of the maintenance personnel can be ensured. At the same time, maintenance personnel should also pay special attention to the fact that the use of safe voltage is not absolutely safe. The national standard stipulates that when the electrical equipment adopts a safe voltage exceeding 24V, it is necessary to take protective measures against direct contact with the charged body.
(5) The circuit with energy storage components must be discharged after power failure
All circuits with energy storage components should be discharged before maintenance. For example, a capacitor stores a certain amount of charge, which is retained for a certain period of time just after the power is turned off. When the human body comes into contact, the residual charge is discharged through the human body, forming an electric shock. Therefore, any circuit with energy storage components should be discharged after being cut off from the grid, and the discharge time should be greater than five times the time constant.
(6) Use lifting tools to pay attention to safety
Machine tool repairs sometimes require the use of lifting tools, and care must be taken when using lifting tools. Before use, check whether the equipment is good. It is not allowed to be overloaded during use. It is not allowed to pull the inclined crane. During the lifting process, it is strictly forbidden to stand under the hanging object.
(7) Design or modification of the line must meet the following requirements
When repairing, it is generally not allowed to modify the line without authorization. If the line is changed, the following requirements must be met: First, in the same line, it is not allowed to connect the attracting coils of two electrical appliances. Because for an AC contactor or an intermediate relay, as long as one appliance operates, its coil inductance increases, and the voltage drop naturally increases. After the two coils are connected in series, the voltage is not able to reach the voltage required for its operation, and the safe and reliable operation cannot be ensured. Second, the multiple electrical appliances in the line are prevented from being operated in sequence, and the other electrical appliance can be connected. Control circuit. For the intermediate relay, do not want anything that can be avoided. The more intermediate relays, the more complicated the line, not only the high cost, but also the inconvenience of maintenance, it is easy to make mistakes; the third is to minimize the number and length of the connecting lines when designing or modifying the line. That is to minimize the phenomenon of two wires connected in parallel and reciprocating.
(8) Replace the damaged component after repairing the cause of the failure
When identifying the fault point and repairing the fault, it should be noted that the fault point cannot be found as the end point of finding the fault, and the root cause of the fault must be further analyzed. For example, when dealing with the failure of a motor burned, it must not be mistaken to believe that if the burned motor is repaired or replaced with a new motor of the same model, the cause of the motor overload should be further ascertained. It is because the load is too heavy, or the motor is not properly selected and the power is too small, because both will cause the motor to overload. Therefore, when dealing with such faults, it is necessary to find out the cause of the fault and replace it before replacing the new appliance.
(9) Various protection performance after maintenance must meet safety requirements
For repaired machine tools, the performance of various protective devices must meet the safety requirements for use. During the maintenance process, all kinds of protection devices of the machine tool should be highly valued, especially the short circuit, overload and interlock protection. Never neglect, in which the short circuit and overload protection are strictly prohibited to ensure the circuit, After the equipment fails, it will work reliably to ensure the safety of the circuit and motor.
(10) Use special tools such as disassembly and assembly of motors
When disassembling the motor end cover, pulley, shaft and bearing, special tools such as copper rods, wooden hoes and hooks are used, and it is not allowed to directly hit with a hammer or a flat shovel.
(11) The electrical equipment of the machine tool after repair must meet the quality standards
After the machine has been repaired, it should be demobilized as much as possible. However, in order not to affect production, it is necessary to resume the normal operation of the working machine as soon as possible, and often take some appropriate and temporary emergency measures, but the emergency measures taken will never allow for perseverance, and the machine will be demobilized in time. After the maintenance of the machine tool is completed, the maintenance personnel should carefully check before the test, and the electrical equipment of the machine tool after repair must meet the following requirements: the insulation resistance is qualified; the wire ends are not stabbed, and the number is written with the label tube; all the joints are tightened; the appearance is neat, no Damage and carbonization; all contacts are complete, smooth and in good contact; pressure springs and reaction springs have sufficient elasticity; steering and resetting mechanisms are flexible and reliable; various armatures are flexible and free of jams; arc extinguishing covers are complete, clean and securely installed The setting value is in accordance with the circuit requirements; the indicating device can normally send a signal.
(12) Power must be tested after troubleshooting
After the machine tool is repaired, it must be powered on and tested by the operator. Safety measures should be taken before the test, carefully check whether the mechanical parts of the limiter, zero pressure, zero magnetic, overvoltage, overcurrent relays, etc. are safe and reliable. When testing, you should pay attention to whether the motor steering, sound, temperature, etc. are normal; the various functions of the circuit, the operating procedures of the control link meet the requirements. The staff should avoid the direction of rotation of the coupling to ensure personal safety.
(13) Civilization maintenance to prevent fire
After the entire maintenance work is over, check the tools used to prevent them from being missed in the equipment. Finally, clean the dirt and debris on the equipment, clean it, disconnect the power supply, and eliminate the fire source before leaving the site. Special attention should be paid to maintenance personnel: when cleaning electrical equipment parts with gasoline, it is strictly forbidden to use open flames and to prevent static sparks.
(14) Pay attention to the accumulation of maintenance experience
After each repair, the experience should be summed up in time and the maintenance record should be made.
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