Development Of Piezoelectric Centre Dynamometer

Rotary parts which are one of the typical hardware fitting have wide scope of applications in machinery manufacturing. Shaft parts, sleeve-like parts and plate parts are all typical parts with external circular surface, the shaft parts not only can be used to support the drive disk assembly, load bearing, but also can transfer torque and motion. Parts are the basic units in the process of mechanical manufacturing, they are one of the indispensable important components of all kinds of mechanical equipments. The machining quality and precision of parts directly determine the overall operational performance and service life of equipment, on the other hand, manufacturing accuracy of the equipment restricts parts precision. For this reason, it must be monitored the cutting process to promote the common development.There are various kinds of dynamometer used for direct measurement of cutting force at home and abroad. At present, platform type dynamometer of piezoelectric and strain, turning dynamometer of cutter bar type, grinding centre dynamometer of strain are widely applied as a direct way to measure cutting force. Aiming at the status quo is blank which piezoelectric centre dynamometer is available to measure the cutting force during processing of rotary parts, according to the structure of machine tool, considering the intercommunity between process of turning and grinding, adopting the piezoelectric sensor based on the piezoelectric effect of quartz crystal, a piezoelectric centre dynamometer is developed to measure cutting force during the machine process of rotary parts in turning and grinding.According to the force condition of the workpiece in the practical process of turning and grinding, this article not just establishes mathematical model of turning and grinding, respectively, but analyses of quantitative relation between the output of dynamometer and the stress of workpiece and proves them with finite element software ANSYS. In order to simulate the state of dynamometer installation under laboratory conditions, a static calibration device of the dynamometer are designed. During static calibration of the integral type dynamometer, there are shortcomings in the structure of dynamometer. In view of these weaknesses, centre dynamometer of combined-type is devised, meanwhile, the concept of load cell is put forward. Static calibration of load cell and centre dynamometer of combined-type turn out that the centre dynamometer has good properties, such as high sensitivity, good linearity and repeatability, which reach the design requirements of cutting force test system. Structure defects of integral-type dynamometer have been improved. And the dynamometer is very suitable for monitoring cutting force in turning and grinding process. In the actual process of turning parts, only one centre dynamometer can be used on machine tool. As a consequence, it is necessary to calculate fitting formula and correction factor of turning and grinding. At last, we can get output of dynamometer in different loading positions with loading different forces.