Nc machine tool spindle bearing assembly and adjustment

Nc machine tool for precision demanding, thus for spindle component has a strict technical characteristic. Ordinary spindle are bearing pair is applied, the points after the front end, the bearing structure of 2 + 2, 2, 3 + 4 + 2, etc. For the front two bearing two supporting device of main shaft bearing assembly, should be made before and after two of eccentricity in the same direction of supporting bearing device, properly choose the size of the eccentricity, the precision of the front bearing should be higher than the accuracy of the rear bearing, after making the assembly of the front end of the spindle assembly positioning looks small eccentric qualitative changes. Rolling bearings rolling bearing clearance and preload when there is a big gap, load will focus on the stress direction on a few rolling body, makes the land bearing stiffness and bearing to land, low stress, rotating accuracy is poor. Will stop rolling bearing preloaded, appropriate rolling body and the inner and outer ring raceway in prestressing contact point, the number of rolling element bearing increased after loading, the stress tends to average, improved bearing ability and stiffness, is advantageous to the reduction of spindle axis drift, advances the rotation accuracy. If the amount of interference is too big, friction and wear of the bearing increased, landed the force will be significant, the relationship between the bearing life and clearance as shown in figure 7 14 on the machining center, angular contact ball bearing on the main shaft device, bearing and spindle to cooperate, common use 1 - 5 um interference fit; Bearings with holes, using 0 5 um clearance fit. Spindle parts used for a period of time, bearing wear gap will increase, will be to adjust the clearance. Therefore, spindle assembly structure must be adjusted with bearing clearance. Angular contact ball bearing clearance adjustment and preload method as shown in figure 7 15. Pairs made is to use of angular contact ball bearing inner ring end face or outer end face grinding to complete. Factory according to the request of preloaded bearing consumption in pairs, not demand to adjust when assembling, and close it with the nut after can obtain precise pre-tightening force. Due to the use of cannot adjust, repair to match. Figure 7 - 16 and shown as spacer adjustment method. Using two sets of adjusting, through two sets of the width of the poor, adjust bearing clearance. Or in the bearing outer ring spacer, assembly with a nut and obtain the pre-tightening force tight inner circle. The adjustment way don't have to remove the bearing, magnitude of prestressing force on workers' experience.