1. Bearing combination design As shown in the figure is a support structure of a common lathe spindle. The front support is a fixed end. It consists of a double-row cylindrical roller bearing with a tapered hole and two one-way thrust ball bearings. Two one-way thrust ball bearings bear axial loads in two directions respectively, and are preloaded with constant spring pressure to eliminate bearing clearance. Double-row cylindrical roller bearings bear radial loads. The taper hole can be used to move on the journal to adjust the radial clearance of the bearing, and to achieve radial preload to improve the rigidity of the main system. The rear support adopts a double-row cylindrical roller bearing with a tapered hole. The inner ring and roller move relative to the outer ring to adapt to the thermal expansion and elongation of the shaft, and the clearance and preload can be adjusted. In this lathe spindle, since the front support close to the working end is used as a fixed end, it bears axial loads in two directions, so other parts of the shaft are not affected by axial loads. Both supports adopt double-row cylindrical roller bearings with tapered holes, which can realize radial preload, so the support rigidity of the shaft is relatively large. The clearance of each bearing can be adjusted, so the rotation accuracy of the shaft is relatively high. 2. Coordination and installation Since the outer ring of the cylindrical roller bearing is subjected to local load, the machining accuracy of the shell hole should be taken as K6 level. Thrust bearings are followed by H5-level precision fit, and the fit between the shell hole and thrust bearing should be machined to H6-level precision. 3. Lubrication and sealing The main shaft support of the lathe is lubricated by circulating oil. If the gear lubricating oil is directly used to lubricate the bearing at the same time, a filter device should be installed. The seal of the lathe spindle. Generally, a “W”-shaped gap sealing device is used. When the rotating speed is high, the contact seal should not be used, so as to avoid the frictional heat diffusion generated by the sealing ring and affect the machining accuracy of the machine tool.  

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