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How to work the transmission system of large hole CNC lathe

The feed mechanism of large hole CNC lathe is an important part of servo system. Besides the high positioning accuracy, it should also have good dynamic response characteristics. The response of tracking command signal of the system is fast and the stability is good. Try to eliminate the transmission clearance and reduce the error of reverse dead zone, such as the coupling with clearance elimination and the transmission pair with clearance elimination measures. The feed transmission system of large hole CNC lathe is usually used as servo feed system. The function of servo feed system is to control the movement of the executive parts after amplification according to the command message from the NC system. It not only controls the speed of the feed motion, but also precisely controls the moving position and track of the tool relative to the workpiece. A typical feed system controlled by the closed-loop of large hole CNC lathe is usually composed of position comparison, amplification parts, driving unit, mechanical feed transmission mechanism and detection feedback element. The mechanical feed transmission mechanism of large hole CNC lathe refers to the whole mechanical transmission chain which transforms the rotation motion of servo motor into the linear feed movement of the workbench or tool holder, mainly including the deceleration device, screw rod nut pair, guide parts and supporting parts.

In order to ensure the transmission accuracy, stability and dynamic response of the feed system of large hole CNC lathe, the requirements of no gap, low friction, low inertia, high rigidity, high resonance rate and suitable damping ratio are put forward for the feed mechanism. In order to meet these requirements, the following measures are mainly adopted: low friction transmission is adopted as far as possible, such as static pressure guide, rolling guide rail and ball screw, etc. to reduce friction. The transmission ratio is adopted to improve the resolution of the machine tool, and make the table accelerate as much as possible to achieve the tracking command, and the transmission inertia converted to the drive shaft is as small as possible. Shorten the drive chain and improve the rigidity of the transmission system by means of pre tightening. For example, the motor directly drives the screw rod, there should be a pre loaded rolling guide rail and a pair of rolling screw rod. The support of the screw rod is designed to be fixed at both ends, and the transmission system stiffness can be improved by means of pre stretching structure.