Many machine tools due to ball screw nut transmission operation most frequent, various components often produce mechanical wear and poor lubrication, and therefore often appear decreased positioning accuracy, backlash is too large, mechanical crawling, serious bearing wear, excessive noise and other faults. When these failures occur, how to make the right diagnosis of ball screw and repair equipment in time. According to the KOS company's technicians introduction, to repair or inspect the first starting from the nut.
Before repairing the screw, first should check the bending of the screw, exceeds 0.1mm/1000mm must be straightened. Then measure the actual thickness of the screw thread, find the maximum abrasions, estimate the screw thread after repair process the thickness decrease, if more than the 15% ~ 20% of standard thread thickness, then the screw to be scrapped, can not be reused. In special cases, also allow to use the method of reducing the outer diameter of the screw to restore the standard thread thickness, but the outer diameter reducing amount shall not exceed 10% of the outer diameter of the original standard. For heavy-duty screw, if threaded portion needs repair, also checking its thickness decreases, the stiffness and strength whether can still meets the original design requirements.
The failures of ball screw and nut in operation mainly are:
1, Large backlash, poor positioning accuracy, processing parts size is not stable.
Ball screw assembly and its support system due to long-running generated wear gap will directly affect the transmission precision and rigidity of CNC machine tools. Failures generally have large backlash, positioning accuracy of instability and other issues.
2, Ball screw nut is not working smoothly, the noise is relatively large.
3, Ball screw nut support bearing wear or bearing pre-load washer with inappropriate.
4, Single nut of ball screw nut wear and clearance occurred; the nut flange plate and the working table are loosened, the gap is generated, the ball screw nut balls wear, double nut clearance occurred.
Original author: http://www.machineballscrew.com
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