The requirement of CNC machining center for feed motion the feed motion of CNC machining center for CNC machining machine tool is the direct object of digital control. Regardless of point position control or contour control, the final dimension accuracy and contour accuracy of workpiece are affected by the transmission accuracy, sensitivity and stability of feed motion. Therefore, the feed system of CNC machine tools should pay enough attention to reducing friction resistance, improving transmission accuracy and stiffness, eliminating transmission clearance and reducing inertia of moving parts.
1、 CNC machining center reduces friction resistance
In order to improve the fast response performance and motion accuracy of the feed system of CNC machine tools, it is necessary to reduce the friction resistance of moving parts and the difference between dynamic and static friction. In order to meet the above requirements, ball screw nut pair, hydrostatic screw nut pair, rolling guide rail, hydrostatic guide rail and plastic guide rail are generally used in the feed system of CNC machine tools. At the same time of reducing the friction resistance, it is necessary to consider that the transmission parts should have proper damping to ensure the stability of the system.
2. CNC machining center reduces inertia of moving parts
The inertia of the moving parts has an effect on the starting and braking characteristics of the servo mechanism, especially on the high-speed running parts. Therefore, on the premise of meeting the strength and rigidity of the parts, the mass of the moving parts and the diameter and mass of the rotating parts should be reduced as much as possible to reduce the inertia of the moving parts.
3. CNC machining center improves transmission accuracy and rigidity
The transmission accuracy and rigidity of the feed transmission system mainly depend on the transmission clearance and the accuracy and rigidity of the screw nut pair, the worm gear and worm pair (in the case of circular feeding) and its supporting structure. The transmission clearance mainly comes from the transmission gear pair, worm gear pair, screw nut pair and their supporting parts. The preload shall be applied or the clearance elimination measures shall be taken. Shortening the transmission chain and setting the reduction gear in the transmission chain can also improve the transmission accuracy. It is an effective measure to increase the drive stiffness to increase the diameter of the screw and to apply pre tightening force to the screw nut pair, supporting parts and the screw itself. Insufficient rigidity will also cause the table (or carriage) to creep and vibrate.