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Requirements of CNC machining machine tools for feed motion

The feed motion of CNC machining tools is the direct object of digital control. Whether point control or contour control, the final dimensional accuracy (accuracy) and contour accuracy of the workpiece are affected by the transmission accuracy and sensitivity of the feed motion (Sensitivity) and stability (explanation: stability and stability; no change). To this end, the feed system of CNC machining 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 (accuracy) of the feed system of CNC machine tools (attribute: automatic machine tools), the friction resistance of moving parts and the difference between dynamic and static friction forces must be reduced. In order to meet the above requirements, ball screw nut pairs, static pressure screw nut pairs, rolling guide rails (TTW guide), static pressure guide rails and plastics (structure: synthetic resin, plasticizer) are generally used in the CNC machine tool feed system , Stabilizer, color material) guide rail. While reducing frictional resistance, it must also be considered that the transmission components should have appropriate damping to ensure the stability of the system (explanation: stable and stable; no change) (The stability of).

2. Improve transmission accuracy (precision) and rigidity

The transmission accuracy (accuracy) and rigidity of the feed drive system are considered from the mechanical structure (consider) mainly depends on the transmission clearance and the accuracy and rigidity of the screw nut pair, worm gear pair (when circumferential feed) and its supporting structure . CNC machining CNC is also known as computer gong, CNCCH or CNC machine tool. It is actually a name from Hong Kong, which greatly reduces the number of tooling. CNC machining of parts with complex shapes does not require complicated tooling. CNC machining is a new type of processing technology and the main work It is to compile the processing program, that is, to convert the original manual to computer programming. If you want to change the shape and size of the part, you only need to modify the part processing program, which is suitable for new product development and modification. In numerical control processing, the control system sends out instructions to make the cutter perform various movements that meet the requirements, and expresses the processing of technical requirements and processing requirements such as the shape and size of the workpiece in the form of numbers and letters. It generally refers to the process of processing parts on CNC machine tools. In order to improve production automation, shorten programming time and reduce CNC machining costs, a series of advanced CNC machining technologies have also been developed and used in the aerospace industry. The transmission clearance mainly comes from the transmission gear pair, the worm gear pair, the screw nut pair and its supporting parts, and the pretension force should be applied or the measures to eliminate the clearance should be taken (pointer to solve the problem). 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 improve 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 moving parts has an impact on the starting and braking characteristics of the servo system (organization), especially the parts that are running at high speed, the inertia of the impact is greater. CNC machining generally CNC machining usually refers to computer digitally controlled precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring and milling machine, etc. The feed route for finishing is basically carried out along the contour of its parts. Therefore, the work of determining the feed route is to determine the feed route for rough machining and empty stroke. 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 may be reduced as much as possible to reduce the inertia of the moving parts.

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