The requirement of feed movement for CNC lathe machining

The traditional mechanical processing is performed by manually operating the ordinary machine tool. During the processing, the mechanical tool is shaken by hand to cut the metal, and the accuracy of the product is measured with a caliper and other tools by the eyes. Modern industry has long used computerized digitally controlled machine tools to perform operations. CNC machine tools can automatically process any products and parts directly according to the procedures pre-programmed by technicians. This is what we call "CNC machining". CNC machining is widely used in any field of mechanical machining, it is also the development trend of mold machining and important and necessary technical means!

So what are the requirements for the feed movement of CNC lathe machining?

　　The feed motion of CNC machining tools is the direct object of digital control. Whether point control or contour control, the final dimensional accuracy and contour accuracy of the workpiece are affected by the transmission accuracy, sensitivity and stability of the feed motion. For this reason, the feed system of CNC machining machine tools should pay full attention to reducing friction resistance, improving transmission accuracy and rigidity, eliminating transmission gaps, and reducing inertia of moving parts.

　　 1. Reduce frictional resistance

　　 In order to improve the rapid response performance and motion accuracy of the CNC machine tool feed system, it is necessary to reduce the friction resistance of the moving parts and the difference between the dynamic and static friction forces. To meet the above requirements, ball screw nut pairs, static pressure screw nut pairs, rolling guide rails, static pressure guide rails and plastic guide rails are commonly used in CNC machine tool feed systems. While reducing frictional resistance, it must also be considered that the transmission components must have appropriate damping to ensure the stability of the system.

　　 2. Improve transmission accuracy and rigidity

The transmission accuracy and rigidity of the feed drive system are mainly determined by the mechanical structure from the perspective of the transmission clearance and the accuracy and rigidity of the screw nut pair, worm gear pair (when circumferential feed) and its supporting structure. The transmission gap mainly comes from the transmission gear pair, the worm gear pair, the screw nut pair and its supporting parts, and the pre-tightening force should be applied or measures to eliminate the gap should be taken. Shortening the transmission chain and setting reduction gears in the transmission chain can also improve the transmission accuracy. Increasing the diameter of the screw and applying preload to the screw nut pair, supporting parts, and the screw itself are effective measures to increase the transmission rigidity. Insufficient rigidity can also cause crawling and vibration of the workbench (or carriage).

　　 3. Reduce the inertia of moving parts

　　 The inertia of the moving parts has an influence on the starting and braking characteristics of the servo mechanism, especially the parts that are running at high speed, the influence of the inertia is greater. Therefore, on the premise of satisfying the strength and rigidity of the parts, the mass of the moving parts and the diameter and mass of the rotating parts are reduced as much as possible to reduce the inertia of the moving parts.