NC lathe spindle bearings generally use angular contact ball bearings, using a micrometer to check the bearing's inside and outside diameter and thickness, compared with national standards to meet the requirements. To measure the thickness difference between the inner and outer rings of angular contact ball bearings, a lever dial indicator (dial indicator), magnetic table base, 3 standard blocks with a length of 100mm, 1 marble flat plate, and 100mm × 100mm × 20mm parallel blocks1 are used.
Small CNC lathe spindle refers to the axis on the machine tool that drives the workpiece or tool to rotate. Spindle components are usually composed of the main shaft, bearings and transmission parts (gears or pulleys). In the machine, it is mainly used to support transmission parts such as gears and pulleys, to transmit motion and torque, such as machine tool spindles; some are used to clamp workpieces, such as mandrels.
Except for machine tools whose main movement is linear motion, such as planers and broaching machines, most machine tools have spindle components. The motion accuracy and structural rigidity of the spindle components are important factors that determine the machining quality and cutting efficiency. Indexes for measuring the performance of main shaft components are mainly rotation accuracy, stiffness and speed adaptability.
① Rotation accuracy: The radial and axial runout (see shape and position tolerance) that appear in the direction that affects the machining accuracy when the spindle rotates is mainly determined by the manufacturing and assembly quality of the spindle and bearing.
② Dynamic and static stiffness: It mainly depends on the bending stiffness of the main shaft, the stiffness and damping of the bearing.
③ Speed adaptability: The allowable high speed and speed range are mainly determined by the structure and lubrication of the bearing, as well as the heat dissipation conditions.
Long-term use of CNC lathes will cause serious damage to the spindle bearings and affect the machine's geometric accuracy. To restore the accuracy, the "directional assembly method" needs to be used to replace and assemble the spindle bearings.