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I. Causes and Classification of NC Machine Electrical Equipment Failures During the operation of the electrical equipment of CNC machine tools, they need to withstand the influence of many unfavorable factors such as the environment and operations, resulting in or causing many failures. Therefore, routine maintenance and inspection are the production operations. Very important and essential part.
Due to the many types of electrical faults and their respective characteristics, it can even be said that the maintenance personnel of CNC machine tools can hardly encounter two faults of the same type, type, and nature during their entire working process.
The faults that occur during the operation of CNC machine tools' electrical equipment are mainly divided into two categories according to the causes of the faults:
One is due to the mechanical vibration during the operation of the electrical apparatus. The thermal effect of overcurrent accelerates the deterioration of the insulation of the electrical components, the burning of the arc, the natural wear of the long-term operation, the influence of the ambient temperature and humidity, and the harmful media such as metal shavings and oil. The erosion, the quality problems of the components themselves, the natural life and other reasons, cause the natural faults of the circuit and the numerical control machine tool electrical not to be able to operate normally. It is an objective existence and cannot be avoided.
The other is due to the fact that the electrical equipment of CNC machine tools is under operation and is damaged by undue mechanical external forces or caused by improper operation or improper installation. It also causes accidents of CNC machine tools and even endangers personal safety. malfunction.
From the fault appearance, a type of fault has obvious appearance characteristics, such as significant heating of the motor and the electrical appliance, smoking, emission of coke odor, or spark, etc., due to the overload of the windings of the motor and the electrical appliance, insulation breakdown, short circuit or grounding. Caused by, it is easy to be found. The other type of fault has no obvious external features, such as improper adjustment of electrical components in the electrical circuit, malfunction of the mechanical action, faulty contact or disconnection of the contact and crimp terminal, damage of a small part, or broken wire. , Or the line is complex and prone to such failures, is the main fault of the control line. This type of fault is often encountered in practice. Since there is no appearance feature, the fault point must be found by means of various measuring instruments and tools to find the fault point, and once the fault point is found, it can be recovered immediately by simple adjustment or repair. CNC machine tool electrical normal operation.
Second, the numerical control machine tool electrical equipment failure analysis and inspection methods When the numerical control machine tool electrical equipment failure, due to the different types of circuits and CNC machine tools have different characteristics, how to use the master of the basic professional operating skills and professional knowledge to carry out Analysis and maintenance is the difficulty and focus of practical training in the maintenance of numerical control machine tools. The correct method is used to analyze the fault phenomenon, and the fault range and fault point are accurately searched to be able to use effective methods to eliminate the faults and repair the CNC machine tool. The specific steps are as follows:
1, the fault investigation before the maintenance When the industrial machinery electrical failure, should not be blindly hands-on maintenance. First of all, it is the first time that the operator of the CNC machine tool or the person in charge in the event of a fault is discovered. It is the first time it occurs suddenly, or it frequently occurs. Is the location of the fault, whether the external phenomenon is smoke, flashover, abnormal sound, the surrounding environment in the event of a fault, or not? Whether there is gas, whether there is corrosive gas erosion, whether there is water leakage, whether the heat source causes electrical damage, etc.; whether someone has repaired, repaired, and what operation and misoperation have occurred.
Because the operators of CNC machine tools are most familiar with the performance of the CNC machine tools, they are also the first to understand the possible causes and locations of failures, which is beneficial to the maintenance personnel of CNC machine tools based on the relevant working principles to determine the scope of fault occurrence and analyze failures. Causes.
Before the inspection, ask, see, hear, and touch to understand the operating conditions before and after the fault and the anomalies that occur after the fault, so as to determine the location of the fault according to the fault phenomenon, and then accurately eliminate the fault. Q: Ask the operator before and after the failure of the circuit and equipment operating conditions and symptoms after the failure, the fault is often or occasionally occurred; whether there is a sound, smoke, sparks, abnormal vibration and other symptoms; whether the cutting force before the failure occurred Yamato frequently starts, stops, brakes, etc.; whether it has undergone maintenance, repairs, or changes to lines. Look: See if there are obvious appearance signs before the fault occurs, such as various signals; the condition of the fuse of the indicating device; the protection tripping action of the electric appliance; the disconnection of the wire; the singeing or fusion welding of the contact; the coil is overheated and burned. Listen: In the premise that the line can run without damaging the equipment, you can power on the test and listen to the sound of the electrical contactors and relays. Touch: Immediately after the power is cut off, touch the motor, transformer, solenoid coil, and fuse to check if there is overheating.
Through the above investigations, we have a preliminary understanding of the phenomena related to failures, thereby reflecting various failure problems. The phenomenon of failures is in one-to-one correspondence with the types of failures. It is not difficult to find as long as we can grasp the signs reflected by the phenomena. Find the fault.
2. Logic analysis method is used to determine and narrow the fault range According to the understanding and understanding of the fault phenomena, the electrical fault phenomena are further divided and categorized, and it is clear whether the fault lies in the motor part, the main circuit part, or the control circuit part fault, or It is to control the failure of the electrical component itself.
3, according to the scope of the fault, find and determine the point of failure After determining the possible scope of the fault, we must further determine the point of failure, to find the point of failure must apply a correct and effective method.
3.1 Visual inspection of the fault area After determining the possible range of the fault, visual inspection is performed on the electrical components and the connecting conductors in the range, for example: melt blowing of the fuses; loosening or detachment of the wire connectors; contactors and relays Touch off or poor contact, coil burned to make the surface insulation paper scorch discoloration, burning out the insulating varnish flow; spring off or broken; the electrical switch action mechanism is blocked failure, etc., can clearly indicate the point of failure.
3.2 When the fault point is determined by the method of power-on commissioning and the fault point is not found through visual inspection, the cause of the fault can be analyzed in combination with the circuit diagram to confirm that the fault will not be further enlarged and the accident of the human body and equipment will be caused. Understand the probable cause, you can power test to check (remove the load connection if necessary), in order to distinguish the fault may be in the electrical part or other parts such as machinery; is on the motor or the control device; is on the main circuit Or in the control circuit, under normal circumstances first check the control circuit, the specific approach is: operation of a button or switch, the line contactors, relays will work in accordance with the order of the required actions. If one of the electrical components is operated in sequence, it is found that the operation does not meet the requirements, which means that the electrical component or its related circuit has a problem. Then perform item-by-item analysis and inspection in this circuit, generally you can find the fault. After the failure of the circuit to be controlled is restored to normal, the main circuit is turned on, the effect of the control on the main circuit is checked, and whether or not the main circuit is operating abnormally is observed.
3.3 According to the scope of the fault, through the detection to determine the fault point in the clear fault range belongs to a certain part, the application of instruments, instruments and corresponding detection methods to further narrow the fault from a larger range, and ultimately determine the fault point.
Method for repairing control circuit of electrical equipment in machine tool maintenance
The maintenance of electrical equipment of numerical control machine tools is one of the important professional skills that must be mastered by the maintenance professional of numerical control machine tools. In actual work, it is necessary to understand the causes and classification of failures in the electrical equipment of numerical control machine tools, and to grasp the basic methods of failure analysis and maintenance.