Introduction to the spindle assembly structure of precision CNC lathes

The spindle of a precision CNC lathe is a hollow stepped shaft. The inner hole of the spindle is used to pass long bars and steel bars when removing the top. It can also be used to pass through pneumatic, electric,medical machining companies and hydraulic clamping devices. The tapered hole at the front end of the spindle is metric 90mm and is used to install the top sleeve and front top. Sometimes a mandrel can also be installed, and the friction of the cone surface can be used to directly drive the mandrel and the workpiece to rotate. The tapered hole at the rear end of the spindle is a process hole.

The CNC lathe spindle is installed on three supports. There are three rolling bearings in the front support. The front is a C-level precision double-row cylindrical roller bearing to bear radial force. This kind of bearing has the advantages of good rigidity, high precision, small size and large load-bearing capacity: the rear support uses a pair of radial thrust bearings.

The spindle support has a great influence on the running accuracy and stiffness of the CNC lathe spindle. The CNC lathe spindle bearing should operate under the condition of no clearance (or a small amount of interference), which directly affects the machining accuracy of the machine tool. Therefore, the clearance of the spindle bearing must be adjusted regularly. The adjustment method of the front bearing clearance is as follows: first loosen the locking screw on the front adjustment nut, and then tighten the adjustment nut. Because the inner ring of the bearing is very thin, and the inner hole is the same as the spindle taper, with a taper of 1-12, Therefore, the inner ring radially elastically expands while moving axially to adjust the bearing radial clearance or the degree of preload. After the adjustment is stable, tighten the locking screw of the adjusting nut.

The radial runout of the CNC lathe spindle affects the roundness and concentricity of the machined surface; the axial runout affects the flatness and pitch accuracy of the aluminum cnc machining parts and its end face. Under normal circumstances, when the spindle runout exceeds the allowable value, you only need to adjust the gap of the front support appropriately to adjust the spindle runout to the allowable value; if the radial runout still does not meet the requirements, the rear bearing should be adjusted.

The lubrication of the front and rear supports of the CNC lathe spindle is supplied by a lubricating oil pump. The lubricating oil fully lubricates the bearings through the oil inlet and takes away the heat generated by the bearing operation. In order to avoid oil leakage, oil groove seals are used at the front and rear supports, that is, there are annular grooves with sawtooth cross sections on the outer surfaces of the front nut and the rear support sleeve. When the CNC lathe spindle rotates, due to the effect of centrifugal force, the oil It is thrown into the oil groove of the flange along the inclined plane (towards the inside of the box). The oil flows to the bottom of the box through the oil return hole, and then flows back to the oil pool in the left bed leg.