Feed Drives for High-Accuracy, High-Speed Milling Machines

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High speed milling (HSM) is recognized as one of the most significant recent innovations in machining. One of the main obstacles to further advancement of HSM is the challenge of designing feed drives capable of reaching the required high speeds and high accelerations while maintaining transient path following accuracy. This is due to the heavy masses to be moved, and the vibration modes of the structure that are excited by the motion. In order to fully utilize the current generation of high speed spindles, axis accelerations of 1g to 2g are required with speeds up to 1 meter per second. In order to achieve this level of performance, it is desirable to have positional servo bandwidths of 100 Hz or more. This project will focus on the feed drives and control strategies of high speed milling machines, to enable higher speeds and accelerations and also to enhance contouring accuracy during high speed motions. Using the high speed milling machines developed at the university, appropriate control strategies will be developed and verified for traditional ballscrew/rotary servomotor drives, direct linear servomotor drives, and hydrostatic leadscrew/rotary servomotor drives. This project is expected to significantly advance high speed machining technology. Practical implementation of this technology may include, for example, the production of aircraft, where structural parts with thin sections milled from solid blocks are replacing riveted sheet metal assemblies, and in the production of forging, die casting, and injection molding dies where high speed milling is replacing electrical discharge machining on a large scale.