High-capacity compact three-component cutting force dynamometer

Abstract

The design is reported of a compact three-component tool-shank dynamometer. It is based on a design in which the load bearing section has its stiffness reduced by two holes symmetrically positioned about the centre-line, and connected by a narrow slit. The holes are positioned to enable strain gauges to record the highest local strains' and, hence to maximize sensitivity and to minimize cross-sensitivity. Experimental analysis has identified the critical location, relative to the hole, at which the maximum surface strain is attained. Improvement of the dynamometer accuracy has been achieved by accurate location of the point of force application to eliminate the cross-sensitivity between the different components. Further improvement of the dynamometer sensitivity has been achieved by appropriate design of the electrical circuits. Force signals have been captured and processed using a micro-computer through specially designed strain-gauge amplifiers and analogue-to-digital converter ADC. A series of tests have been carried out to determine the dynamometer static and dynamic characteristics. Mathematical models have been developed to characterize and formulate the dynamometer performance.