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UBC Theses and Dissertations

Rotary-axial spindle design for large load precision machining applications Usman, Irfan-ur-rab

Abstract

Normal stress electromagnetic actuators can be used as both an axial bearing and an in-feed motor in precision machine tool applications that require only millimeter-range axial stroke, such as silicon wafer face grinding or meso-machining. The rotary cutting stage may be integrated with the axially-feeding stage in a rotary-axial architecture. This typology allows the use of independent rotary and axial actuators acting on a single moving mass, rather than an axial actuator moving an entire rotary motor assembly in the feed direction as in typical machine tool architectures. Non-collocated resonances are therefore minimized and thrust and radial stiffness is increased through the elimination of intermediate lateral and thrust bearings, and achievable closed loop positioning performance is improved. This thesis presents the working principle, design, and analysis of radially-biased electromagnetic bearing/actuators for large load precision rotary-axial spindle applications, and the integration of such an actuator in a full scale prototype to be used as a silicon wafer face grinder. The experimental results indicate that the rotary-axial spindle with radially-biased thrust bearing/actuator is capable of achieving less than 7 nm resolution over a 1.5 mm axial stroke, a worst case load capacity of approximately 5000 N and a best case load capacity of over 8000 N, with rotary-axial coupling of less than 30 nm axial error at 3000 rpm.

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Attribution-NonCommercial-NoDerivatives 4.0 International

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