Daily Maintenance of CNC Machining Center
As a machine tool mainly used to process box and shell parts, the machining center is worth hundreds of thousands to millions. It is generally the key equipment in the key processes of the enterprise. Once the machine is shut down, the loss is often great. Therefore, in order to give full play to the benefits of the machine tool, we must pay attention to the maintenance and repair work. Because most of the daily electrical faults of CNC machine tools are electrical faults, electrical maintenance and repair are more important.1) CNC system control part2) Servo motor and spindle motor
Focus on noise and temperature rise. If the noise or temperature rise is too large, find out whether it is a mechanical problem such as bearing or the parameter setting of its matching amplifier, and take corresponding measures to solve it. For example, if there is abnormal sound during the movement of the servo shaft, and there is no obvious parameter change after verification, it is suspected that the mechanical noise may be caused by the lead screw, coupling and non concentricity with the servo motor. Disconnect the motor from the coupling and operate the motor separately. If the motor still has noise, adjust the speed loop gain and position loop gain appropriately, Make the motor silent. If there is no noise, judge that it is the concentricity between the lead screw and the coupling, re correct the concentricity, and then connect with the motor. The problem can be eliminated.
3) Measurement feedback elementIncluding encoder, grating ruler, etc., check whether the connection of detection elements is loose and whether they are polluted by oil or dust.4) Electrical control part
Check whether the three-phase power supply voltage is normal; Check whether the electrical components are well connected; Check whether various switches are effective with the aid of CRT display diagnosis screen; Check whether all relays and contactors work normally and whether the contacts are in good condition; Whether the thermal relay, arc suppressor and other protective elements are effective; Check whether the temperature of components inside the electrical cabinet is too high. For poor contact of contactor contact, the contactor can be disassembled, the high-temperature oxide on the contact surface can be scraped off with a small file, then the sundries can be wiped out with absorbent cotton and alcohol, reassembled, and then the contact can be conducted with a multimeter.
5) Improve utilization
If the machining center is idle for a long time, when it needs to be used, first of all, each moving link of the machine tool will affect its static and dynamic transmission performance due to grease solidification, dust and even rust, reduce the accuracy of the machine tool, and the blockage of the oil circuit system is a big trouble; From the electrical point of view, the electrical control system hardware is composed of tens of thousands of electronic components, and their performance and life are very discrete. If it is not used for a long time, when power is suddenly transmitted, the components will be damaged in high current and strong voltage. Therefore, in a period of time without machining task, it is best to run the machine tool at a low speed, and at least power on the NC system frequently, or even every day.
I have encountered this situation: a horizontal machining center, using FANUC system. After running the warm-up program, it processed and found that the qualified parts were processed in the morning, and the processed parts were unqualified by noon. After inspection by the on-site processing personnel, the positioning and fixture on the machine tool are not deformed or loose. However, when the spindle box is not processed and stationary, it will deviate downward by 0.1mm along the direction of the gravity axis. The technician judges that the temperature compensation fails or the temperature sensor has poor contact. However, the phenomenon still occurs after replacing the temperature sensor and temperature module and re entering CNC parameters and temperature compensation parameters. After expert consultation, it was finally found that it was not the sensor problem, but that there was a 2-meter-long and 1-meter-wide skylight facing the main shaft and column on the machine tool. At noon, the sun directly shines on the main shaft and column, resulting in thermal deformation. After the skylight is covered, the spindle box returns to normal. This is a typical maintenance error caused by improper maintenance. Therefore, proper daily maintenance provides convenience for overall maintenance in the future.