The feed drive of CNC machine tools is the direct object of CNC machining. Whether it is point control or contour control, the coordinate accuracy and contour accuracy of the workpiece after Z are all affected by the transmission accuracy, sensitivity and stability of the feed drive. For this reason, the CNC machine tool feed system generally has the following characteristics.

Low friction 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 frictional resistance between the moving parts and the difference between dynamic and static friction. In order to meet the above requirements, commonly used in the CNC machine tool feed system are ball screw nut pairs, static screw nut pairs, rolling guides, static guides and plastic guides. At the same time, the moving parts should be properly damped to ensure the stability of the system.

High transmission accuracy and rigidity

The transmission accuracy and stiffness of the feed transmission system mainly depend on the transmission gap and the accuracy and stiffness of the screw nut pair, worm gear pair and their supporting structure from the mechanical structure. The transmission gap mainly comes from the transmission gear pair, worm gear pair, screw nut pair and their supporting parts, so the feed transmission system is widely used to apply pre-tightening force or other measures to eliminate the gap. Shortening the transmission chain and setting a reducer on the transmission chain can also improve the transmission accuracy. Increasing the diameter of the screw and applying pre-tightening force to the screw nut pair, support and the screw itself are effective measures to improve the transmission rigidity.

The inertia of moving parts is small

The inertia of the moving parts affects the starting and braking characteristics of the servo mechanism, especially the starting and braking characteristics of the high-speed running parts. Therefore, on the premise of meeting the strength and rigidity of the parts, the mass of the moving parts should be reduced as much as possible, and the diameter and mass of the rotating parts should be reduced to reduce the inertia of the moving parts.

No gap

In order to improve the displacement accuracy and reduce the transmission error, it is first necessary to improve the accuracy of various mechanical parts, and secondly, to eliminate various gaps as much as possible, such as; use couplings, gear pairs, ball screw pairs and supports to eliminate gap structures.