Automatic Analysis Algorithm Of Workpiece Locating Error For Any Contact Locating Scheme

In the modern manufacturing industry,machine tool fixture is generally widely used,on the one hand it can be guarantee the processed workpiece has been in the position of a relatively correct processing technology to meet the necessary requirements;on the other hand,if the machine tool fixture as a separate system,its own functions are relatively strong,not only can adapt to the production of large quantities of products,but also can meet some of the special,personalized product production.Along with our country manufacturing industry technical level unceasing enhancement,the requirement of machine tool fixture has been increased,so the study of machine tool fixture work becomes more and more important.And the size of the machine tool fixture positioning error can be objectively expressed a fixture system can satisfy the requirement of processing technology,therefore,research how to efficient,convenient and accurate method of calculating the fixture positioning error on overall manufacturing industry technical progress of our country has a profound meaning.Although the traditional,classic calculation method of positioning error has a lot of,such as typically have limit position method,plane dimension chain method,differential method and so on,though these algorithms simple principle,calculation process is not very complicated,but has a big problem is not with general versatility.In other words,is that calculating certain or some conditions the positioning error of machine tool fixture system can only use a specific or some certain kinds of calculation methods,but not all calculation method can be used.Under the big situation,research a kind of generality,highly automated operation such as database positioning error of the calculation method of the performance has the necessity very much,this automatic calculation of implementation,to promote CAFD(Computer Aided Fixture Design)system process has a practical meaning.This paper analyzes the manufacturing error,installation error and manufacture error of positioning element influence on workpiece position error,summarizes the contact of workpiece and positioning components,is the change of contact point to the path model and size dimension chain model,the change of contact point described as contact size error.This method is not only suitable for the unilateral contact positioning scheme,but also suitable for any edge contact positioning scheme.Combined with the coordinate transformation technology,differential analysis is used to establish theanalysis model of the workpiece position offset and positioning error as a function of the change of the contact point position.Taking into account the independence of the size and angle of the contact pair,the data table method is proposed to realize the independent check of the variables,and to ensure the correct calculation of the position offset of the workpiece.The calculation method of database form is easy to realize by computer programming.According to the fixture workpiece contact in different ways,the workpiece position error model,and use the change of contact point to the path model and size dimension chain model,the change of contact point described as contact size error,then calculating the position offset table method.In this paper,we discuss the problem of calculating the position offset of the workpiece from the positioning error,and propose the kinematics analysis model of the workpiece fixture system.In the form of a table stored in the database,which is easy to program in computer automated analysis of positioning error.