Requirements Of CNC Lathes For Feed Transmission Mechanisms

The feed drive system of CNC lathes commonly uses servo feed systems to work. The function of the servo feed system is to control the movement of the executive parts after amplification according to the command message transmitted by the numerical control system, not only to control the speed of the feed movement, but also to control the moving position and trajectory of the tool relative to the workpiece. A typical CNC lathe closed-loop control feed system is usually composed of position comparison, amplification parts, drive units, mechanical feed transmission mechanisms and detection feedback elements. Among them, the mechanical feed transmission mechanism of CNC lathe refers to the entire mechanical transmission chain that changes the rotational motion of the servo motor into a table or tool holder linear feed movement, mainly including a reduction device, a screw nut pair, a guide part and its supporting parts.
In order to ensure the transmission accuracy, stability and dynamic response characteristics of the CNC lathe feed system, the feed mechanism is put forward with requirements such as no gap, low friction, low inertia, high stiffness, high resonance rate and suitable damping ratio. In order to meet these requirements, the following measures are mainly adopted: try to use low-friction transmission, such as hydrostatic guides, rolling guides and ball screws, etc., to reduce friction. The transmission ratio is used to improve the resolution of the machine tool and accelerate the table as much as possible to achieve the tracking instruction, so that the transmission inertia converted by the system to the drive shaft is as small as possible. Shorten the transmission chain and improve the rigidity of the transmission system by preloading, such as the use of electric motor to drive the screw directly, there should be a pre-loaded rolling guide rail and rolling screw pair, the screw support is designed to be fixed at both ends, and the rigidity of the transmission system can be improved by pre-stretching structure.
CNC lathe feed mechanism is an important part of the servo system, in addition to high positioning accuracy, it should also have good dynamic response characteristics, the response of the system tracking command signal should be fast, and the stability should be good. Try to eliminate the transmission gap and reduce the reverse dead zone error, such as using a coupling to eliminate the gap, using a transmission pair with clearance elimination measures, etc.