Safe operation when servicing the machine

When an electrician repairs or refits a machine tool, the following safety practices must be observed.

(1) maintenance to power outages, electrified maintenance must have a guardian to repair the machine tool electrical must be carried out under the conditions of power outage, single maintenance, non-live work is strictly prohibited. When it is necessary to carry live work, in addition to maintaining good insulation between the live body and the earth, the operator must also have a professional electrician guarding to alert and stop the unsafe behavior of the operator at any time. At the same time charged maintenance should pay special attention to the short circuit. When overhauling or measuring closely spaced terminals, special care must be taken to prevent short circuits. Because of the close proximity of the terminals, the potentials are different, and careless measurement of the maintenance will cause a short circuit accident. In general, the eyes are very close to the maintenance site when repairing. In the event of a short-circuit accident, splashing short-circuit sparks can easily harm 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 electrical circuit principle of the machine tool The electrical maintenance of the machine tool is a very practical work. It advocates daring to practice, but it firmly opposes blindly. Maintenance personnel must be familiar with the basic principles of electrical machine tools.

(3) Master general maintenance methods, reasonable selection of components The machine tool electrical circuits are simple and complex. For a simpler electrical control circuit, since the number of electrical components and the number of conductors are few, it is clear at a glance that, after a fault occurs, faults can be identified by examining the electrical appliances one by one and the conductors one by one. However, for machine tools with complicated control lines, it is difficult to use the above method to check for electrical faults. When a machine tool with complex control lines fails, the maintenance personnel must flexibly apply various methods according to the nature of the fault and the specific conditions under the premise of familiarizing with and understanding the machine control circuit diagram. For example, the power-off checker uses a multimeter to measure the resistance, the power-on checker uses a voltage and current method, and other methods include an intuitive method, a short-circuit method, etc. When necessary, various methods can be used interchangeably to quickly and effectively identify a fault. point. After finding the fault point, it is necessary to take the correct repair method for different fault conditions and locations. Do not easily use methods such as replacing electrical components and repairing lines, and do not allow easy modification of lines or replacement of electrical components with different specifications to prevent Human error. Need to replace the circuit components, should be a reasonable choice, can not be convenient and large and small, but can not be small and large, in order to ensure normal circuit performance and work safety and reliability.

(4) Inspection and maintenance lighting The safety voltage maintenance lamps shall use safe voltages of 36V and below. The lamp caps shall have protective covers. It is forbidden to use voltages higher than 36V. Because the voltage of 36V is the safe voltage value that the country stipulates to use in general occasions, the maintenance of the machine tool uses the voltage not higher than 36V, and if the maintenance personnel get an electric shock, it is easier to get rid of it, which can ensure the personal safety of the maintenance personnel. At the same time, maintenance personnel should also pay special attention to the use of safety voltage is not absolute security. National standards stipulate: When the electrical equipment adopts a safe voltage exceeding 24V, protection measures must be taken to prevent direct contact with the charged body.

(5) Circuits with stored energy components must be discharged after a power outage. Circuits that have energy storage components must be discharged before maintenance. For example, a capacitor stores a certain amount of charge, allowing it to retain a certain amount of time just after the power is turned off. When the human body contacts, the residual charge will be discharged through the human body to form an electric shock. Therefore, any circuit that has an energy storage element should be discharged after it is disconnected from the power grid. The discharge time must be greater than five times the time constant.

(6) Using lifting tools CAUTION Safety Machine repairs sometimes require the use of lifting tools, and care must be taken when using the lifting tools. Before use, check whether the equipment is in good condition. Do not allow overload and lifting during use. Do not allow tilting and lifting. In the lifting process, it is forbidden to stand under hanging objects.

(7) When the design or modified circuit must meet the following requirements for maintenance, it is generally not allowed to modify the circuit without permission. If you change the line, you must meet the following requirements: First, in the same line, it is not allowed to connect the attraction coils of two electrical appliances in series. Because for AC contactors or intermediate relays, as long as there is an electric appliance, its coil inductance increases, and the voltage drop naturally increases. After the two coils are connected in series, the voltage cannot reach the voltage needed for its operation, and the safe and reliable operation cannot be ensured; secondly, after the multiple electric devices are prevented from operating in sequence, the other electric device can be connected. Control circuit. For intermediate relays, do not want to do anything. The more intermediate relays, the more complex the lines, which not only cost high, but also make it inconvenient to maintain, and are prone to errors. Third, when designing or revising the lines, the number and length of the connection lines should be minimized. That is to minimize the phenomenon of two wires in parallel and reciprocating.

(8) Maintenance should be replaced after eliminating the cause of the failure. When finding fault points and repairing faults, care should be taken not to find the fault point as the end of the fault, but must also be further analyzed to investigate the fault. root cause. For example, when dealing with the breakdown of a motor, it must not be erroneously assumed that if the burned motor is repaired or replaced with a new motor of the same type, the motor should be further identified. This 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 be overloaded. Therefore, when dealing with such failures, you must replace the new appliance after finding the cause of the failure and remedying it.

(9) After the maintenance, all kinds of protection performance must meet the safety requirements of the machine after maintenance. The performance of various protection devices must meet the safety requirements when used. During the maintenance process, various protection devices for the machine tool should be highly valued, especially short-circuit, overload and interlock protection. Do not carelessly negligent. Among them, the short-circuit and overload protection is strictly prohibited in order to ensure the circuit, After a device malfunctions, reliable operation ensures the safety of the circuit and the motor.

(10) When using a special tool to disassemble or disassemble the motor end cap, pulley, shaft, and bearing when using a special motor, use special tools such as copper rods, wooden hammer heads, and pull hooks, and do not use direct hammers or flat spades.

(11) After the repair of the machine tool electrical equipment to achieve quality standards After the machine has been repaired, it should try to demobilize. However, in order not to affect production, it is necessary to resume the normal operation of the working machinery as soon as possible, and some appropriate and temporary emergency measures are often taken. However, the emergency measures taken must not be allowed to act and the machine tool should be demobilized in time. After the machine tool is repaired, the maintenance personnel should check carefully before the test run. The repaired machine tool electrical equipment must meet the following requirements: the insulation resistance is acceptable; the wire end is not punctured, and the number is written with the label tube; all the connectors are tightened; the appearance is neat and clean. Damage and carbonization; all contacts intact, smooth, good contact; pressure springs and reaction springs have sufficient elasticity; flexible and reliable operation and reset mechanism; various armature movements are flexible, no jamming; arc quenching cover is complete, clean, and firmly installed The setting value is in line with the circuit requirements; the indicating device can send signals normally.

(12) Power must be turned off after troubleshooting After the failure of the test machine tool has been repaired, it must be commissioned with the operator's cooperation. Before the trial run, safety measures should be taken to carefully check whether the mechanical limiters, zero pressure, zero magnetic, overvoltage, and overcurrent relays are safe and reliable. During the test run, it should be observed whether the motor steering, sound, temperature, etc. are normal; whether the various functions of the circuit and the control procedures of the control link meet the requirements. Staff should avoid the rotation direction of the coupling to ensure personal safety.

(13) Maintenance of civilized fires After the completion of the maintenance work, the tools to be used for inventory should be checked to prevent them from being left in the equipment. Finally, clean the dirt, debris, clean the equipment, disconnect the power source, and eliminate the fire source before leaving the site. Special attention must be paid to maintenance personnel: When cleaning electrical equipment parts with gasoline, it is forbidden to use an open flame and prevent static sparks.

(14) Pay attention to accumulative maintenance experience After each maintenance, it is necessary to sum up experience in a timely manner and make maintenance records.