| Gear is an important basic part,widely used in many fields.By using CNC gear machine is the only choice to meet the requirements of high precision,high efficiency and complex shape processing,which have an important position and role.CNC system of gear machine tool is the key component to determine the performance,function,reliability and cost of machine tools.Due to its high productivity,continuous generating grinding is a popular finishing process for gears with small and middle sized modulus.With the exist of nondeterminacy,randomness and complicacy of the grinding process,why we can not build the mathematical model precisely to control.The automatic and intelligent research of gear grinding is of great significance for the optimization of machining quality and precision.This study focus on CNC system,do the research for intelligent grinding process of gear,add real-time compensation during gear machining process.For this purpose,the main researches can be summarized as follows:Theoretical investigations are conducted to identify the influence of tool and workpiece setting on the resulting cutting speed in the contact zone for continuous generating grinding especially with a higher number of starts.Depending on the geometrical setting of the gear and grinding worm,the resulting cutting speed can be higher or lower than the set tool circumferential speed.Based on multi-body system theory,the topological structure of CNC worm wheel grinding machine is described.The errors are analyzed and calculated by means of homogeneous transformation matrix.The kinematic error modeling of the gear grinding machine is carried out.By abstracting them into moving pair and rotating pair sequentially,according to the kinematic theory of the rigid body system and the principle of homogeneous coordinate transformation,the homogeneous coordinate transformation matrix for the error of each component is derived.On the basis of small error compensation motion hypothesis and differential transformation principle,the interference factors of each axis error affected by grinding machine accuracy are analyzed and decoupled.Finally,the mathematical model of geometric error decoupling for gear grinding is obtained.The error data are compensated by software error compensation method and SIEMENS 840 D system error compensation method.The CNC gear grinding machine Kapp KX160 was tested,and the compensation of X,Y,Z,A and C was carried out respectively.The gear error which before and after the error compensation are measured by using P26 CNC precision measuring center.The result of geometric accuracy of the machine tool and machining accuracy enhance at the same time are verified by comparing the data.The experimental results show that the geometric accuracy of the worm wheel grinding machine is positively related to the machining accuracy of the gear. |
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