1. The role of CNC machine tool to adjust the clearance between spindle and bearing
Too large or too small radial and axial clearance of CNC machine tool spindle bearings are the main causes of CNC machine tool failures. If the gap is too large, the spindle will jump, and the workpiece will produce ellipse, edge circle or ripple, etc. If the gap is too small, the spindle will be hot and damaged at high speed. When adjusting the CNC machine tool, first loosen the locking screw 5 and nut 4, so that the inner ring of bearing 7 moves to the right relative to the conical journal of the spindle. Due to the action of the cone surface, the inner ring of bearing produces radial elastic expansion, which reduces the clearance between the roller and the inner and outer rings. After the CNC machine is adjusted properly, the locking screw 5 and nut 4 should be tightened. The clearance of bearing 3 can be adjusted by nut l. In general, only the front bearing can be adjusted. Only when the required rotary accuracy is still not reached after the adjustment of the front bearing, the rear bearing can adjust the axial clearance and accuracy of the spindle.



2. The operation procedure of bearing before adjusting CNC machine tool
(1) Prepare a hook wrench, a hammer, a driver, open the headstock cover and place it smoothly.


(2) Hook the nut at the front end of the spindle with a hook wrench and pull it counterclockwise. If not, use a hammer to tap the hook wrench, loosen the nut.


(3) Loosen the locking screw, then tighten the adjusting nut counterclockwise with a hook wrench. After adjusting, tighten the locking screw with a driver and tighten the adjusting nut.


(4) check the spindle bearing clearance size, hand rotation spirit bracket, no block phenomenon, then attack measurement spindle radial runout and axial movement, make it ≤0 0imm, close the spindle box cover, make the spindle high-speed operation ih, bearing temperature ≤60℃.