The continuous innovation of high-speed machining centers demonstrates that fully utilizing the latest achievements in the field, especially the latest advancements in drive and control technologies, is key to continuously improving the high-speed performance, dynamic characteristics, and machining accuracy of machining centers.
Over the past decade, significant advancements in drive technology and control systems have driven continuous innovation in machining center structures and performance improvements. The application of electric spindles, linear motors, torque motors, and high-speed CNC systems has played a decisive role in enhancing the high speed, high dynamic range, and high machining accuracy of machining centers.
linear motor
Currently, most high-speed machining centers used for mold processing still use servo motors and ball screws to drive linear axes. However, some machining centers have adopted linear motors. Since this linear drive eliminates the need for transmission components to convert rotary motion into linear motion, it can significantly improve the dynamic performance, movement speed, and machining accuracy of the axis.
Machine tools driven by linear motors can significantly improve productivity. For example, when machining electrodes for electrical discharge machining, the machining time can be reduced by 50% compared to using a traditional high-speed milling machine.
Linear motors can significantly improve the dynamic performance of high-speed machine tools. Since most molds are three-dimensional curved surfaces, the tool axis must constantly brake and accelerate when machining these surfaces. Only with high axis acceleration can a given contour be tracked with a constant feed per tooth over a short path at high trajectory speeds. The smaller the radius of curvature of the surface contour and the higher the feed rate, the higher the required axis acceleration. Therefore, the axis acceleration of the machine tool greatly affects the machining accuracy of the mold and the durability of the cutting tool.
Torque motor
In high-speed machining centers, torque motors are widely used to achieve the oscillation of rotary tables and the oscillation and rotation of fork-shaped spindle heads. A torque motor is a synchronous motor whose rotor is directly fixed to the component being driven, thus eliminating the need for mechanical transmission components; it is a direct drive device, similar to a linear motor. The angular acceleration achievable by a torque motor is six times higher than that of traditional worm gear drives, reaching up to 3g when oscillating a fork-shaped spindle head. Because torque motors can achieve extremely high static and dynamic load rigidity, they improve the positioning accuracy and repeatability of rotary and oscillating axes.
Currently, some manufacturers have adopted linear motors and torque motors to drive linear axes (X/Y/Z) and rotary oscillating axes (C and A) in their high-speed machining centers.
It should be mentioned that the combination of direct-drive linear axes and direct-drive rotary axes gives all motion axes of the machine tool high dynamic performance and adjustment characteristics, thus providing optimal conditions for machining free-form surfaces of molds at high speed, high precision and high surface quality.
