Developent Of On-Machine Measurement System For Five-Axis Tool Grinder End Mill

On-machine contact measurement(OMCM)can effectively guarantee the machining accuracy of the workpiece and improve the machining efficiency,thus it is widely used in advanced five-axis CNC machine tools.The geometric parameters of end mill is an important standard of the quality of end mill,however nowadays the method mainly used for the measurement of the geometric parameters of the end mill is the optical offline method.There are two disadvantages of this method.One is optical measurement is limited by imaging quality and optical instrument resolution so there is a gap of the accuracy between contact measurement and optical measurement.The other is low efficiency of offline measurement,at the same time secondary clamping of parts after offline measurement will make new clamping error which will decrease the precision of end mill.To avoid the above defects,this paper uses OMCM on five-axis tool grinder to measure geometric parameters of intergral end mill.Following work is completed in this paper:(1)The math models of geometric parameters of end mill are established.Selected the measured geometric parameters based on the analysis of structure of end mill and working demand.Then established the math model of spiral edge,end tooth edge line,groove bottom curve and core thickness curve.(2)A method to plan the probe path of on-machine measurement(OMM)is researched.Defined the general probe path of five-axis OMM system according to the principles of OMCM.The conceptions of probe point,probe intermediate point and probe initial point are defined.Then determined the number of probe points to calculate the parameter according to the model of this parameter.The spatial coordinate of each probe point and the probe initial point in the workpiece coordinate system is determined by the coordinate system transformation,the measurement auxiliary parameter and the probe shape and position parameter.Then the probe swing angle,probe vector and probe intermediate point coordinates are determined by the principle of optimal probe efficiency and highest detection accuracy.Finally,the measurement NC code is generated according to the coordinates of the detection point,the coordinates of the detection intermediate point,the coordinates of the detection initial point,the detection swing angle and the detection vector.(3)An algorithm to calculate the geometric parameter of cylindrical end mill is researched.Firstly real coordinate of probe point are got by compensation of probe ball radius.Then algorithm is selected the by comparing the number of probe point(NPP)and the number of to calculate the parameter(NCP).If NPP is the same as NCP then select reverse algorithm,else if NPP is more than NCP,then select least squares method.Finally the parameter is calculated by the corresponding algorithm.(4)An OMM software system is designed and developed.Designed an OMM system according to the requirements of OMM.The OMM system was developed in the C# language environment on the VS2012 platform.The system can automatically generate the measurement NC code by selecting the measured parameter,the input probe shape position parameter and the measurement auxiliary parameter,and process the acquired probe point coordinates after performing the measurement action to obtain the measurement result and display it on the human-computer interaction interface.Finally,the OMM system is used on a five-axis grinder and the application of measurement of each parameter was verified.According to the measurement results,the OMM system has high accuracy and good stability.