Localization Of Positioning Errors

With the increasing requirements for product quality and production efficiency in machinery manufacturing industry, computer aided fixture design is more and more concerned. Location error analysis and calculation in fixture design is the essential link for guaranteeing the geometric accuracy of process. Aiming at the problem that the current location error is lack of a general analysis and calculation method, the paper analyses the cause of location error and tries to find the general calculation method.The paper takes integrated positioning of the workpiece in the fixture as the object of study, general calculation method of location error as the target, and the precise definition of location error as the breakthrough point. Stylized calculation method of location error can be established.The paper puts forward concept of theory benchmark. According to the positioning status of workpiece, theory benchmark in various situations of integrated positioning can be determined by using geometrical method. The error of dimension between process reference and theory benchmark in the process dimension direction is defined as the location error. The formation mechanism of location error can be improved. The location error can be characterized as dimension error between the specific point, line, surface, which is easy to slove by using analytic method. Achieve the stylized calculation of the location error in the situation of integrated positioning. Benchmark relationship diagram can describe the geometrical relationship between process benchmark and theory benchmark. Mathematical model of the relation between relevant benchmark can be established, which provides a theoretical basis for evaluating locating scheme quantitatively.The paper illustrates the application of process path graph in the aspect of position tolerance design of process, which considers the geometric quantity and required precision of process. The paper comprehensively calculates the location error of geometrical parameter of the process by means of benchmark relationship diagram. The combination of the position tolerance path diagram and benchmark relationship diagram is conducive to the more comprehensive analysis of the process scheme.In this paper, with the help of secondary development function of API function of SoildWorks software, parametric modeling of the fixture and workpiece can be realized by using VB software. In the SoildWorks assembly function module, the specific location of theory benchmark and process benchmark can be marked. According to the measuring tool, the result of location error can be directly obtained. It has certain practical value to the computer aided calculation of location error.