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1、2021/11/17,SCUT,1,3.8 The function and design method of process planning file,The term process route(工艺规程) refers to the process planning file in which the process and operation method are specified. In another word, the sequence of each operation, the part dimensions, tolerance and technical requir
2、ement, technical equipment and measures, cutting parameters, standard production time, and levels of operators skill are all included in the process planning file.,2021/11/17,SCUT,2,3.8.1 The format of a process sheet工艺过程卡,The format of a part process sheet made by different companies is quite diffe
3、rent. In 1982, the pre-mechanical industry ministry(原机械工业部） issued the ministry standard to regulate the format of a part process sheet (referred to JB/Z1 187.3-82). Nevertheless, operation sheets are largely identical but with minor differences. Usually the following items should be included in a p
4、rocess sheet. Name of part and type ； Name and No. of part ； Raw material ； Name of operation ； Name of plant .,2021/11/17,SCUT,3,In single or small batch type production, only a general and simple process sheet is prepared, shown as the following sample, where the product name and type, part name a
5、nd drawing No., the kinds and material of the roughcast, operation No. name and content, the workshop for each operation, equipments and time scheduling are all included。,2021/11/17,SCUT,4,2021/11/17,SCUT,5,In Batch type production,usually a detailed operational sheet is planned, show as the sample
6、given below,in which not only the content of a process sheet must be included ,but also the detailed description of the operational step and position,the operational dimensions and specifications are included. An operational draft should be given for some main operations, in which the desired dimens
7、ions achieved in that operation, the tolerance, the roughness and the setup must be marked. In single or small batch type production, some important parts also ask for an operational sheet.,2021/11/17,SCUT,6,2021/11/17,SCUT,7,Part operational draft,2021/11/17,SCUT,8,Before products are manufactured,
8、technical and production preparation can be made according to the demands of process planning sheet.,According to the process planning sheet, the kinds, type and number of machine tools, the production area needed , the plan arrangement of equipment, the number, type and class of operators required
9、can all be decided. Then, the planning of factory preparation, enlarging or rebuilding will be decided accordingly.,2021/11/17,SCUT,9,The functions of process planning sheet,The functions of the process planning sheet are as follows ： (1)The main technique for giving regulations to guide the product
10、ion (2) The basis of organization and management (3) The main information to guide the building, enlarging or rebuilding of a mechanical factory,2021/11/17,SCUT,10,3.8.2 The analysis of the processing performance (加工性分析）,1 . Inspect the design drawing：check if the dimensions are complete and structu
11、ral expression is clear. 2. Analyze if the specifications are reasonable, including （1）The dimensional accuracy；（2）The geometrical shape accuracy；（3）The positional accuracy between the main machined surfaces （4） Requirement of the surface quality；（5） Requirement of the heat treatment .,2021/11/17,SC
12、UT,11,3. Check if the material is properly chosen Use the usually used material as far as possible if it meets the requirement, such as 45 steel 4. Analysis of the processing capability related with the part structure (1) The concept of part structural processing capability: the feasibility and econ
13、omical performance when manufacturing a part When planning the part machining process routine, the analysis of the cutting performance is mainly concerned . (2) The local structural requirement when machining a part （局部结构的加工工艺性） (3) The overall structural requirement when machining a part（整体结构加工工艺性）
14、,2021/11/17,SCUT,12,Examples about the local structural requirement,(1) Convenient for the approaching and receding of the cutting tool,(2) Make sure the cutting tool can work normally,2021/11/17,SCUT,13,(3) Make sure the machining is efficient,2021/11/17,SCUT,14,(4) Avoiding deep hole machining,(5)
15、 Use external connection in place of internal connection,(6) One setup to machine those surfaces that have position requirement or in the same direction,2021/11/17,SCUT,15,(7) Sufficient stiffness required suitable for HSC or multi-cutters,2021/11/17,SCUT,16,Question: what about the overall structur
16、al processing capability(整体结构的工艺性）?,(1) Choose the standard and general parts as much as possible; Under the condition that meets the service requirement, take the economical accuracy and roughness as far as possible; Choose materials with good cutting performance as far as possible; Offer reference
17、s easy to be clamped and located; Save material and reduce the weight.,2021/11/17,SCUT,17,3.8.3 Design procedures of the process planning,Design procedures of the process planning Firstly, the function, importance and working condition of the part should be clarified. If the design details are consi
18、dered unreasonable or wrong during inspection, suggestions to modify the design can be proposed.,2021/11/17,SCUT,18,3.8.4 Process route planning,It includes selection of reference surface(基准选择）,machining method, classification of process phases (划分加工阶段,rough machining, self-finish machining and fini
19、sh machining), sequencing the operations（确定加工顺序）, determining the degree of operation distribution（工序分散性）, arrangement of hot working （热处理安排） or inspection and other auxiliary operations .,Simple Discussion: Is it necessary to classify process phases? (加工阶段） How to determine the degree of operation
20、distribution?(工序分散程度）,3.8.5.1 Decide the machining sequence,3.8.5.2 Arrangement of heat and surface treatment,3.8.5.3 Arrangement of inspection operation,3.8.5.4 Arrangement of other operations,3.8.5 Arrangement of operations,2021/11/17,19,SCUT,3.8.5.2 Arrangement of heat and surface treatment,In or
21、der to improve the mechanical and cutting performance of the material, heat treatment is often arranged during machining. Annealing and normalising can release the internal stress and improve the cutting performance of material. Arranged before machining, sometimes normalized after rough machining F
22、or some large and complex casting, in order to reduce the deformation caused by internal stress, a manual time-dependent stress release treatment(人工时效处理） is often arranged after rough machining, but it is better to arrange a natural time-dependent treatment（自然时效） before rough machining.,2021/11/17,2
23、0,SCUT,3.8.5.1 Decide the machining sequence,The machining sequence of each surface should follow the following principles, which are: perform rough machining before finish machining, perform datum surface machining before that of other surfaces, perform main functional surface machining before less
24、 important surface machining, perform plane surface machining before hole surface machining. According to the above principles, the accurate datum surface should be machined first. The finish machining of the most important surface is usually arranged to be the last operation in order to avoid damag
25、e during work handling, and ensure the machining accuracy. Sometimes, arrange the machining of less important and small surfaces in the last operation, such as the machining of a bolt hole.,2021/11/17,21,SCUT, Quality treatment(调质处理） can improve the mechanical performance of the material. Thus, many
26、 medium carbon steels and alloy steels are often treated by this method. Arranged before (sometimes after) rough machining Quenching or carbonising treatment can raise the surface hardness and wear resistance. Arranged before grinding or after final operation. Surface treatment ( including electropl
27、ating and oxidising) can raise the corrosion resistance and wear resistance, and improve the appearance. Arranged in the end.,2021/11/17,22,SCUT,3.8.5.3 Arrangement of inspection operation,Inspection is the most important operation in ensuring product quality and avoiding rejects. In each operation,
28、 the operator should inspect the product himself . On the basis of this, an independent inspection operation should be arranged under the following conditions such as after all the rough machining, before the finish machining and after delivering to other workshop, before and after important operati
29、ons, and after the final operation.,3.8.5.4 Arrangement of other operations,During the operation, some assistant operations such as deburring, demagnetising and rinsing can be arranged after some operations when needed.,2021/11/17,23,SCUT,2021/11/17,SCUT,24,1) selection of machine tools, technical e
30、quipment (including cutting tools, fixtures and inspection tools) and auxiliary tools for each operation.,2) selection of metal removal, operation dimensions and tolerances for each operation,3) Selection of metal cutting parameters and standard operation times 。,4) technical economical analysis,5) form the process file,