Structure Design of Biaxial Rotary Milling Head with High-Torque, High-Precision and Mechanical Spindle

Abstract

As a key component of heavy five-axis linkage CNC machine tools, the existing mechanical biaxial rotary milling heads are usually driven by worm gear, timing belt, or multi-stage gears. Worm gear is inefficiency to transmit motion, hard to maintain the accuracy and difficult to eliminate all clearance; Timing belt can be seriously worn and cannot maintain good accuracy; and multi-stage gears transmission has defects such as long chain, low transmission stiffness. This paper aims at designing a biaxial rotary milling head with large output torque of 3000Nm, high precision and high rigidity. So a new design for biaxial rotary milling head with mechanical spindle, gear transmission and swinging fork structure is proposed. An integral supporting axis is applied to increase the rigidity of A-axis; through the closed numerical loop control based on precise encoder and the decoupling technology of feed motion of A/C axis, the contradiction between large reduction ratio and high precision transmission is solved, and then the requirement of high positioning accuracy (10") is met. Theoretical calculation and simulated analysis shown, the new design not only can guarantee transmission accuracy and dynamic characteristics of biaxial rotary milling head, but also can improve its structural stiffness and meet the high demands of large torque, high precision and high rigidity.