Assignment of allowances for mechanical processing of parts by the calculation-analytical method

Abstract

When completing a course project in the disciplines "Technology of Production of Automobiles and Tractors" and "Technology of Production and Repair of Automobiles", students of specialties J8 Automobile transport G11 Mechanical engineering design a workpiece from which a part is manufactured by mechanical processing of surfaces, the drawing of which is given to the student as a task for developing a technological process. In the process of studying these disciplines, students in practical classes get acquainted with the method of assigning allowances for mechanical processing of workpiece surfaces, which allows them to draw up a drawing of the workpiece. The purpose of this work is to help students who are completing a course project on developing a technological process for machining a part to gain a deeper understanding of the influence of various factors on the amount of allowance that must be assigned to the machining of each surface of the workpiece. The computational and analytical method of assigning allowances, which is considered in this work, allows the student to analyze the features of performing technological operations in which a certain surface of the workpiece will be processed, and thus assign the allowance that is minimally necessary to perform this processing. The guidelines include a statement of the main considerations that should be taken into account when assigning allowances in mass production conditions, when workpieces are processed by cutting tool, pre-set to the required size. Also considered is the processing option with individual tool setting for each workpiece, as well as multi-pass processing (such as grinding) with a gradual approximation of the size of the surface being processed to the required size. The presentation of the material is accompanied by references to recommended literature and test tasks, which will facilitate the work of students when working out the content of practical classes and completing the course project. The guidelines also include an example of the assignment of prom specific and general allowances for processing one of the surfaces of the workpiece using the computational-analytical method.