Design Method Of Plane Blank Size Based On Reference Vector

In the traditional blank size design method,the size of the part drawing is directly used as the template design to mark the blank size.The blank size reference is consistent with the reference on the part drawing.Obviously,this method ignores the differences between the processes,causes the cumulative error of the blank size to affect the manufacturing of parts,and affects the precision of the parts.The rationality of the blank size design,especially the rationality of selecting the blank size reference,has an important influence on the size accuracy of the workpiece in the machining,because the blank size error is large,if it accumulates in the part processing,on the one hand,it may lead to excessive blank allowance,increased consumables,increased costs and reduced production efficiency;On the other hand,the shortage of blank allowance directly led to the failure of parts processing.Therefore,it is necessary to minimize the influence of blank size error on machining allowance and accuracy,and to ensure the rationality of blank size design.The rationality of the selection of the blank size reference influences the target size(roughing allowance on each surface of the blank and the size between the blank surface and the processed surface)and its error.Starting from the link between the process size and the blank size,based on the method of establishing the path diagram of process size,the blank size path diagram was established.According to the principle of the shortest size path,the rough reference is used as the blank size reference,which reduces the influence of the blank size error on the target size.The example proves that when the blank size is in one direction,selecting the blank reference and marking the blank size according to the principle of the shortest size path plays a positive role in improving the size accuracy of the target size.In this paper,the plane blank size is studied.Because the positioning of the workpiece in the plane is combined positioning,there is more than one rough reference,and the size of the blank in the plane is also more complicated.In the case of combined positioning of workpieces,based on the principle of size path diagram to explain the blank size and its characteristics,taking the blank size error as the objective of minimizing the impact on the target sizes,the principle of determining the blank size reference is given.First,multiple rough references are is abstracted as a reference vector,and the theoretical reference of the plane blank size is determined by the reference vector.If the theoretical reference is not at the intersection of the blank elements,the blank size reference is determined by the principle of proximity,and the general method of the size design of the plane blank is summarized.The design of the angular position of the plane blank is also applicable to this method and has been analyzed and studied.Finally,through an example,the expressions of the target size are listed by the new method and the traditional method respectively,and the analysis and numerical calculation are performed to verify the correctness of the new method.This article mainly did the following work:(1)Analyze the position of the workpiece in the plane,and three kinds of combined positioning methods for workpiece positioning in the plane are obtained;(2)Based on the rough reference analysis under combined positioning,combined with the vector features,the reference vector is used instead of several rough reference,and the reference vector determination method is studied in combination with the three combined positioning conditions in the plane;(3)Combining the concrete parts examples,the new method and the traditional method are used to design the blank size,and the blank size path diagram is established.The expression and calculation of the target dimension are compared to prove the superiority of the new remarking method.