Inspection and maintenance of ball screw

Inspection and maintenance of ball screw

The failure of the ball screw is diverse and there is no fixed pattern. Some failures are gradual failures, which require a development process, and become more and more serious as the use time increases; sometimes they are sudden failures, generally without obvious signs, but suddenly occur, such failures are various Unfavorable factors and the interaction of the outside world. Therefore, to determine the true cause of the fault through correct detection is the prerequisite for fast and accurate maintenance.

1) Inspection and repair of clearance between ball screw nut pair and support system

　　 When the CNC machine tool has a large reverse error, unstable positioning accuracy, or tool marks across the quadrant, first check whether there is a gap in the screw system. The detection methods are: use a dial indicator to match the steel ball in the center hole of one end of the screw to measure the axial movement of the screw, and another dial indicator to measure the movement of the worktable. Rotate the screw in the forward and reverse directions, observe the values reflected on the two dial indicators, and confirm the fault location according to the changes in the values.

　　A) Inspection and repair of the clearance of the screw support bearing

　　 If the indicator of the measuring screw is not swinging when the screw rotates forward and backward, it means that the screw does not move. If the pointer of the dial indicator swings, it indicates that the lead screw is moving. The difference between the maximum and minimum measured values of the dial indicator is the axial movement distance of the screw. At this time, we have to check whether the back cap of the support bearing is locked, whether the support bearing has worn out, and whether the preloaded bearing washer is suitable. If there is no problem with the bearing, just re-fit the pre-loaded washer. If the bearing is damaged, the bearing needs to be replaced, refitted with a pre-loaded washer, and then the back cap is tightened. The size of the axial movement of the screw mainly lies in the accuracy of the preloaded washer of the supporting bearing. The most ideal state of the screw mounting accuracy is that there is no positive and negative clearance, and the support bearing should have an interference of about 0.02mm.