Three kinds of mechanical fault diagnosis methods commonly used in ordinary machine tools - News - Global IC Trade Starts Here.

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In order to determine whether it is necessary to replace or repair the faulty part of the diagnostic object or the entire diagnostic object, and to specify the most appropriate preventive duty cycle or content, the results obtained by the diagnosis during use of the machine are required. Any machine, before repair, can not be rushed to disassemble, first of all must carry out pre-demolition static and dynamic inspection and diagnostic operation, provide as much information as possible for fault analysis, based on fault analysis, and develop preliminary repair plans and projects. Perform part removal. Otherwise, blind dismantling will only take half the effort and cause repairs. It even causes the accuracy of the equipment to drop, or damage the components, causing new faults to occur.
Diagnostic operation is mainly through the no-load operation and load operation, to diagnose the key problems in the use of mechanical equipment. In the diagnosis, it should be combined with the operator's situation report, daily record, repair parts replacement table, accident analysis and daily maintenance files to focus on fault diagnosis. The diagnosis of no-load operation is mainly caused by human sensory hearing, visual, olfactory, and tactile diagnostic equipment failure. The main contents are as follows.
1. Diagnose the abnormal noise of the transmission gear in the gear box of the equipment. The no-load operation should be judged step by step. If the noise of a certain speed is abnormal, the parts related to this speed can be initially identified. Such as gears, shafts, bearings, discs, etc., effective damage or wear. Then open the gearbox cover for further inspection. Look at the appearance quality of the gears for failure, such as fracture, deformation, pitting, wear and so on. Use a micrometer to measure the distortion of the gear shaft and check if the bearing clearance is too large.
2. Diagnose the cause of the heating of the rotating or sliding parts of the bearing. For example, the sliding bearing heat is mainly caused by the serious wear of the bearing bush or shaft diameter, the surface roughness becomes thicker, the friction between the shaft and the bearing bush increases at high speed, and the impact phenomenon occurs, or the bearing clearance is too small, or Caused by other reasons. The flow of the moving bearing heat is mainly caused by the adjustment of the bearing clearance is too small and the lubrication conditions are deteriorated. If the bearing body generates excessive heat, an annealing discoloration will occur. In the diagnosis, the principle of difficulty and easyness should be implemented first. Firstly, whether the lubrication meets the requirements is checked. If the bearing clearance is too small, the exploratory diagnosis is performed through the amplification gap. Finally, diagnose after disassembly.
3. The main cause of vibration in the equipment. The faulty vibration of the equipment is often caused by unbalanced rotating parts, wear of the supporting parts, looseness of the transmission mechanism, misalignment or inflexibility, poor contact of the moving parts, and poor transmission quality. When looking for a source, you should start by figuring out the frequency of faulty vibrations. Under normal circumstances, the magnitude of the main frequency can be measured to find the location of the faulty vibration according to the transmission relationship.
4. Find oil leaks in lubrication and hydraulic systems. The main diagnostic equipment is the parts that are leaking during operation, and the cause of the oil leakage is analyzed. Some of the oil leakage is caused by unreasonable equipment design, and some are caused by improper selection of seals. Some are also caused by cracks and blisters in the equipment. There are many reasons for this. Only through the idling of equipment, and trial and error, can we find the root cause and completely eliminate the leak.
5. Determine the cause of the movement disorder of the mechanical component. For example, if it is necessary to judge the cause of the mechanical transmission interruption, the motion cannot be in place, the malfunction or the incomplete function, the movement interruption position can be seen only by the idle equipment, and the specific part of the functional failure can be generated. Load operation diagnosis 1. Determine the wear of the machine's related parts, such as guides, bearings, etc., and the causes of the accuracy failure caused by improper assembly. For lathes and milling machines, the name materials are generally used as experimental parts to check the geometric accuracy and surface roughness of the workpieces. According to the shape error of the workpiece and the situation caused by the surface ripple, the problem of the problem of the equipment is analyzed.
2. Make the equipment card work in a common state, check the performance of the fault during the load operation, especially the vibration, temperature, noise, and loss of function. In the experimental operation diagnosis diagnosis operation, in order to accurately determine the position and the main cause of the failure from among many possible estimations caused by the failure, it is simple and easy to use the experimental method for diagnosis. In practice, the commonly used experiments are as follows:
1. Isolation method: Firstly, according to the working principle and structural characteristics of the equipment, several possible main causes of the fault are estimated, and then the parts where these causes occur are isolated to diagnose the operation. In the judgment, it is necessary to queue the non-fault causes one by one to find out the parts that have a prominent effect on the occurrence and disappearance of the fault. Once the fault location is identified, you can further find and analyze the cause of the fault. For example, if the spindle box of the lathe is abnormal, if it is opened, it is difficult to judge which gear is making an abnormal sound at a time. At this time, the gear can be isolated and judged by the shifting gear. If several files make an abnormal sound, you can find out the common gears of these several transmissions for inspection. If only one block has an abnormal sound, you can find the gear that is used only in one gear for inspection.
2. Heuristics: When the fault cannot be accurately judged, based on the fuzzy estimation, the tentative adjustment is made from the most probable part. By changing the working conditions of the adjustment part, mainly the gap size, observe whether there is a significant impact on the fault phenomenon to determine the root cause of the fault. For example, the lathe phenomenon occurs in the machining process. Although there are many influencing factors, the biggest possibility is that the gap between the middle slide and the small slide is too large. A common possibility is that the wear between the lead screw and the nut that realizes the infeed of the middle slide is severe or improperly adjusted, causing the gap to be excessive. The general possibility is the oblique strip of the large slide and the small slide, reducing the gap between the slide and the guide rail, and then adjusting the double nut of the transverse feed screw. Reduce the gap between the lead screw and the nut. If the problem cannot be solved, check the tool holder positioning mechanism to improve the quality of the large slide and the guide rail.
For faults with more influential factors, it is not only possible to use one method in diagnosis, and it is often necessary to use several methods for diagnosis at the same time. Generally speaking, it is necessary to minimize the scope of judgment and research problems through isolation, and to determine the specific parts of the problem through comparison and heuristics, and finally to make accurate judgments through measurement and replacement. Adhering to such a method of thinking is conducive to improving the accuracy of judgment problems and is conducive to improving work efficiency. As for the specific examples, in fact, in the judgment cases of the above methods, the idea of ​​the fault comprehensive method has been penetrated, and after careful analysis, it can be found that each of the listed faults is never diagnosed by only one method. Clear, but the result of a comprehensive judgment based on one method.