A CNC lathe for processing fan impellers has a numerical control system of FANUC 0i mate TD, spindle variable frequency open loop control, and the spindle is equipped with an encoder. This device often has a fast and slow instability at the feed rate, but the position is basically correct. No alarm when there is a fault. The X and Z axis feed speeds are unstable, but sometimes they are stable. When it is unstable, the device is restarted and stable. According to the above phenomenon, the author judged that the spindle speed measurement is not accurate. Only turn on the spindle, observe the spindle speed display on the display, and find that the display speed is basically consistent with the set speed (1 000r/min). However, the speed of the display is not only unstable but the number of digits can be distinguished, but the other three are also flashing, but it is not clear what number has been changed. Basically, it is still three digits of 1, 0, and 0. Then measured by the tachometer, the spindle speed is basically stable at 1 000r/min. Accordingly, it is more recognized that the spindle encoder is defective. The encoder inspection was removed and the structure was found as shown in the drawing. However, during the dismantling process, the key was not seen, and the retaining ring was not seen. Only the retaining ring groove was seen, and there was more oil stain and obvious wear on the encoder shaft. This confirms that the encoder shaft slips in the pulley (spindle drive) shaft and the detected spindle speed does not match the actual speed. For this economical numerical control, the spindle speed is open loop control, and there is a mechanical gearbox behind the spindle motor, so the feed speed is proportional to the detected spindle speed. Therefore, when the detected spindle speed is unstable, the feed speed is not stable. However, what is the cause of the key missing? We further removed the bearing on the left side of the wheel axle and found the worn key. After careful inspection and testing, it was found that the length of the standard key is not enough here, and it may slide out of the joint to cause the connection between the encoder and the pulley shaft to be disengaged. However, since the encoder can be driven with a small torque, the grease can be driven, of course unstable, and the measured speed is not true. In order to ensure the connection between the encoder and the pulley shaft is good and reliable, with an extended button, the problem is completely solved. Pvc Marble Sheet,Plastic Uv Marble Sheet,Commercial Bathroom Marble Sheet,Uv Pvc Marble Sheet Shandong Zeen Decoration Material Co., Ltd. , https://www.zeendecor.com