RESOLUTION OF NUMERICAL CONTROL MACHINE TOOL MODIFICATION PROBLEMS USING A SYMBIOSIS OF MACHINERY DIAGNOSTICS, MODAL ANALYSIS, STRUCTURAL DYNAMICS MODIFICATION AND ACOUSTIC INTENSITY ANALYSIS

摘要

A multi-million dollar retrofit project was initiated to update a number of older numerical control machine tools. The retrofit replaced the servo control systems, the indexing motors, drive systems and spindle motor. One machine was upgraded as a prototype, but several dynamic problems in both the indexing systems and spindle drive became apparent. These dynamic problems were unacceptable in their effect on machining accuracy. Acoustic intensity measurements were used to pinpoint the source of an irritating 3 KHz tone. This tone indicated a significant amount of energy resulting in a high displacement in the indexing motors. Frequency response measurements of the motor response vs. the power supply input quantified the motor problem and the acoustic levels. Modal analysis was applied to the axial resonances of the index motors to determine the response of the mechanical coupling and run up/down tests were used to determine the spindle motor drive problems.