1. Design topic analysis 1. Product function analysis The loom guide plate is an important part of flat knitting machine, which plays the role of needle running. 2. Machining surface of parts The machining surface of parts includes: excircle, 2 * ~ 8 holes, internal and external contours and keyway. 3. Determine the machinable scheme of the machined surface through part analysis: the lower part of the part belongs to rotary parts, and the machining of the excircle has certain limitations, which is especially suitable for turning. Other methods include finishing, grinding or replacing grinding with turning. This mainly depends on the shape and processing requirements of the parts. Some holes can't be machined by turning, but they can be finished by other machining methods, such as drilling, milling and reaming. Generally determined by the position of the hole axis. If it coincides with the cylindrical axis, it can be processed on a milling machine. Machining special surfaces, mainly the internal and external contours of parts, is mainly done by milling or machining centers, and the rest are machined by turning, milling and grinding according to the situation. Structural manufacturability of parts: parts are small in shape and difficult to process, so we can't blindly determine their processing technology by ordinary processing. Because the lower surface of the contour of the part has stepped cylinders with grooves, it is not easy to process it at one time, so the lower surface (two cylinders) of the contour is processed first, and then the upper surface contour is milled. (Analysis of technical requirements of parts: 1. Accuracy requirements of parts: According to the drawings of parts, the size requirements of workpieces are not large, and the surface roughness is not high, but there are certain requirements for the use of workpieces, so it should be improved accordingly during processing. The circle of φ 15.9 is required to be perpendicular to the needle surface, and it is a little difficult to drill two φ8 through holes on this surface. 2. Requirements for heat treatment of parts: The hardness of vacuum quenching after processing is HRC62-64, and vibration grinding is needed. It can be seen that the requirements for the working environment of parts are high and the strength of workpieces is good). 4. Analyze the production conditions, production equipment and production batches. The processing technology of this part adopts ordinary lathe and CNC milling machine or machining center and decentralized processing production mode. This graduation project requires that the existing CNC machine tools in our college be used as optional processing equipment and mass production methods. The production plan is: 400 pieces/batch, and the production cycle is two weeks (including heat treatment). Compared with ordinary machining, numerical control machining has the advantage of highly concentrated working procedures, which can reduce many complicated fixtures, reduce the number of times of workpiece clamping, improve labor productivity and reduce the accumulated errors of workpiece clamping. 5. The first week of design task analysis: according to the subject, collect data, understand the function and workplace of the yarn guide parts of the loom, be familiar with the product drawings and related technical requirements, and complete the mold opening report; The second week: design the NC machining process of loom guide plate parts and fill in the NC process card; The third week: compile the NC machining program of loom guide plate parts; The fourth week: debug NC machining program with simulation software and learn CAPP related knowledge; The fifth week: the computer aided process planning (CAPP) framework of guide plate parts is compiled; The sixth week: design the CNC machining fixture of loom guide plate parts, draw and complete the fixture assembly drawing; The seventh week: draw the fixture parts drawing and sort out the design instructions; Week 8: graduation design defense. 2. Description of process planning and design 1. Steps of making process plan: (1) Be familiar with and analyze the main basis of making process plan, analyze the structure and manufacturability of parts, and determine the key technical problems of parts manufacturing. (2) Determine the blank, including selecting the blank type and its manufacturing method, and drawing and drawing the blank map. Calculate the total allowance, blank size and material utilization rate. (3) Draw up the process route. (4) Determine the machining allowance of each process, calculate the process size and its tolerance, and draw the process diagram. (5) Select the fixed cutting amount and calculation time. (6) Determine the technical requirements and inspection methods of each major working procedure. (7) Make technical and economic analysis and choose the best scheme. (8) Prepare the process document 1. The determination and material analysis of the blank can be defined as the blank size from the drawing size. The diameter of the excircle is 1 10mm and the length is 65 mm The material is mainly Cr 12MOV. Because this part is used for cutting, structural steel should be selected as the material of this part. The selection of materials mainly considers the following aspects: hardness HRC38；; Parts belong to machining. (1) Hardness HRC38: Hardness shall be ensured by heat treatment. The specific location of the process should be stated in the process. The principle is that the cutting performance should be good, the process should be reasonable and the process cost should be minimum. (2) Hardness requirements are mainly ensured by heat treatment. (3) The material of this part: it belongs to the difficult-to-process material. (4) Good cutting ability: Cutting performance is very important in parts processing, which is related to the selection of cutting parameters and heat treatment. It plays a vital role in the final quality of parts. To sum up, the material of parts directly determines the cost of heat treatment of workpieces, and the mechanical properties of workpieces are also directly related to heat treatment. Hardness, strength, plasticity and toughness are all factors that determine the good cutting performance of the workpiece. It is best to choose easy-to-process materials such as 45 steel. However, due to the special reasons of this part, its performance may be elastically deformed after heat treatment. Therefore, it has good cutting ability before cutting, rather than after preheating treatment, which can reduce the large deformation of parts after processing. This article comes from: Free Graduation Design Information Network (www.lw328.com). Detailed source reference: /onews.asp? id=2464

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