CNC system design, use and maintenance, must be considered to frequent the failure of the site to give the alarm, the alarm circuit work, on the one hand in the screen or the operation panel gives the alarm information, on the other hand issued a protective interrupt command, the system Stop working to check for faults and repair.
According to the composition of the numerical control system, working principle and characteristics, combined with our experience in maintenance, the common fault location and fault analysis are as follows.
First, the power part
The power supply is the part of the energy support that sustains the normal operation of the system, and the direct result of its failure or failure is causing the system to shut down or destroy the entire system. Generally in Europe and the United States, this kind of problem is relatively small, in the design of this factor is not much consideration, but in China due to power fluctuations, poor quality, but also hidden as a high frequency pulse of this type of interference, Of the factors (such as sudden power outages, etc.). These causes can cause power failure monitoring or damage. In addition, the CNC system part of the running data, set the data and processing programs are generally stored in the RAM memory, the system power, by the power of the backup battery or lithium battery to maintain. As a result, downtime is relatively long, plug the power supply or memory may cause data loss, so that the system can not run.
Second, the servo drive system
The service system is connected to the power grid, the mechanical system, etc., and has been in the process of frequent start and running, so this is the more faulty part.
1. The main faults are:
① system damage. Generally due to network voltage fluctuations are too large, or voltage shock caused. Most of China's power grid quality is not good, will bring the machine voltage overrun, especially instantaneous limit, such as no special voltage monitor, it is difficult to find, in the search for fault reasons, to be noted, there Some are due to special causes of damage.
② no control instructions, and motor high-speed operation. The reason for this failure is the speed loop open loop or positive feedback.
③ processing of the workpiece surface can not meet the requirements, take the arc interpolation axis for the emergence of the boss, or motor low-speed crawling or vibration, such failures are generally due to improper adjustment of the servo system, the shaft gain system is not equal or with the motor Matching is not appropriate, the solution is to carry out good adjustment.
④ insurance blown, or motor overheating, and even burn out, such failures are generally mechanical load is too large or stuck.
Position ring This is a numerical control system to issue control instructions, and with the location detection system feedback value compared to further complete the key task of control tasks. It has a very high frequency of operation, and connected with the peripherals, so prone to failure.
2. Common faults are:
① control ring alarm: may be measuring circuit open; measurement system damage, damage to the internal control unit.
② do not send instructions on the movement, may be drifting too high, positive feedback, bit control unit failure; measurement components damaged.
③ measurement of component failure, the general performance of no feedback value; machine can not return to the reference point; high-speed leakage pulse alarm may be due to the raster or read head dirty;
Third, the programmable logic controller interface
CNC system logic control, such as the knife management, hydraulic start, mainly by the PLC to achieve, to complete these control must collect the control point of the state information, such as breaker, servo valve, light and so on. So it is a wide range of external signal source and the implementation of components connected to change frequently, so the possibility of failure is more, and the type of failure is also ever-changing.
Due to environmental conditions, such as interference, temperature, humidity exceeds the allowable range, improper operation, improper parameter setting, may also cause downtime or failure. There is a factory of CNC equipment, boot soon after the loss of CNC ready to signal, the system can not work, the inspection found that the body temperature is high, because the ventilation filter has been blocked, causing the temperature sensor action, replace the filter, the system work The Do not follow the operating procedures plug the circuit board, or no static protection measures, etc., may cause downtime or even destroy the system.