Research On Dynamometer With Sensors Cross Arrangement

With automation machinery industry rapidly developed,this stage cutting condition monitoring for NC machining center are mainly direct observation and cutting force measuring way.From the perspective of intelligent measuring,cutting force can better realize unmanned control,monitoring system can effectively identify the state of cutting force and cutting tool,monitoring system detects feedback force value,takes measures such as timely withdrawal to avoid damage to the workpiece and the tool.Meanwhile,study the deformation of the workpiece caused by cutting forces,tool wear and machine vibration are of great significance to improve the surface quality of the workpiece and tool life.At present,different types of dynamometers have been developed at home and abroad,which are adjusted to measure multi-dimensional force,and meet the corresponding test accuracy and natural frequency.This paper develops a new type of piezoelectric dynamometer to solve the three-dimensional force measurement problem of closed CNC machine tool cutting.According to performance of the piezoelectric sensor,a dynamometer with vertical sensor arrangement has been proposed,the main sensitivity is improved,three-dimensional force measurement has three different calculation methods.The diamond arrangement and square arrangement of the sensors have been compared and analyzed.In order to solve the problems of low stiffness and sensor offset of the combined type dynamometer,three integrated dynamometer schemes has been proposed,and the third scheme has been confirmed.The shell structure of integral dynamometer has been optimized.Four core parameters of the dynamometer has been determined by analyzing the elastic ring deformation and natural frequency of the shell.The finite element method has solved three-dimensional static deformation of the dynamometer,and proportional relationship between the support force of sensors and the load,Technical requirements of the shell processing that can meet the test accuracy have been proposed.According to possible cooperation of the elastic ring groove width and the sensor,two methods of direct assembly and assembly using a rod device has been proposed.The experiment tests that outer ring of the dynamometer can influence with preload force of four sensors,the range calculation method of the dynamometer has been determined,and three-dimensional output of the dynamometer under two preload modes of the sensor have been compared.In order to verify test accuracy,a static calibration experiment of the sensor has been performed,and three-dimensional accuracy and sensitivity of the combined and integrated dynamometer has been compared.Three-dimensional consistency of integral dynamometer has been verified through variable loading point experiments.Natural frequency percussion experiments has verified whether that the dynamometer meets the requirements of dynamic testing.According to experimental results of the calibration,static performance errors of the dynamometer has analyzed.The relationship between the difference in all directions'sensitivity of the sensor and the sensor assembly deflection error and the crosstalk has been deduced theoretically.To prove load sharing effect of the integral dynamometer,three-dimensional output distribution ratio of the combined and integral dynamometer has been compared and verified.The ratio of the shear to the tensile output of under side loading has been analyzed.