【導讀】此論文在第一章緒論中主要介紹了塑料模具現(xiàn)階段的發(fā)展狀況，在現(xiàn)代模具設計中采用了大量的新技術，新工藝和新材料。模具設計已經(jīng)成為一種綜合型技術。還介紹了注射模具的主要組成部件及模板的材料選擇。藝、注塑成型參數(shù)的選擇。品的設計及設計中應考慮的因素。的幾何形狀、尺寸精度和表面質(zhì)量。在第三章塑料模具的設計中介紹了塑料模具設計的基礎知識包括：注射模具與注射機的關系、澆注系統(tǒng)的設計、成型零件的結(jié)構設計。每個零件的設計步驟一般由產(chǎn)品分析及零件選擇、塑件幾何特性分析、注射成型機的選擇、注射成型機參數(shù)的校核、澆注系統(tǒng)的設計、成型零件的機構設計、成型零件的尺寸計及模具的零件等組成。

　　

【正文】 rinking in radial direction. The force to strip the sheet metal hoop around the punch is called stripping force and the force that pushes down or eject up the sheet metal jammed in the die cavity is called pushing or ejecting force,respectively.The stripping, pushing and ejecting forces are obtained by utilizing the pushing and ejecting devices of the press as well as that of the punch and die. It isnecessary to calculate the stripping, pushing and ejecting forces by considering the die structure when selecting the press and designing the punch and die. There are many factors influence these forces, including the mechanic properties and thickness of the blank, the shape and dimension of the workpiece, the clearance between the punch and die, the scrap size and the lubrication condition. 2.　Technological properties analysis of blanking workpieceThe analysis of the technological properties of blanking workpiece is the adaptability of the blanking workpiece to blanking process, namely, whether the shape, the dimension and the tolerance of the blanking workpiece meet the demand of the blanking process or not. Whether the technological properties of the blanking workpiece is reasonable or not, has a great influence on the quality of the blanking workpiece ,the die life and the productivity.The blanking workpiece must meet the following demands:(1) shape of the blanking workpieceThe shape of the blanking workpiece must be simple and symmetrical, with less waste in blank layout. If only the distance between the three holes should be kept, and the outer shape of the workpiece is not so important, the workpiece can be redesigned to adopt blank layout without waste with such arrangement, the material utilization ratio may increase by 40%. Moreover, there are two workpieces produced in one blanking , so the blanking productivity is doubled and the production cost is decreased. Obviously the technology property of the improved blanking workpiece is better than that of the original one.(2) Roundness radius of the blanking workpieceSharp corner should be avoided in the blanking workpiece except when adopting less waste arrangement or using insert die. A suitable roundness radius should be adopted .(3) Width and depth of the local protrusive or incurvate region of the blanking workpieceThe width of the protrusive or incurvate region of the blanking workpiece should not be too small. The lancing and groove, should not be too narrow and too long, otherwise the die life and the workpiece quality would be decreased.(4) Aperture dimension of the blanking workpiece If the aperture dimension is too small, the punch would fracture or bend easily under pression. The minimum dimension of the aperture punched depends on the mechanical properties of the material, the punch strength and the die structure. In the case of punching small aperture , if a protecting jacket is used, the punch would not be damaged easily and its stability can also be improved。 therefore, the minimum dimension of the aperture punched can be decreased.(5) Distance between holes in the blanking workpieceThe distances between holes or between the hole and edge should not be too small. Otherwise, the material between the holes may twist. In the case of pound blanking process , the die may break easily due to the material is pulled into die easily。 in the case of blanking small holes with small distance between them, the phenomena that the punch jammed in die always happens due to the bending of the punch. If the edge of the punhed hole does not parallel to the edge of the workpiece outline, the distance between them should be langer than t 。 on the contrary,the distance between them should be langer than .3. Determination of technology scheme in blanking According to the characteristics of the blanking workpiece,the technology scheme of the blanking is determined based on the analysis of the blanking process (1) Combination of the blanking processBlanking process can be divided into single blanking,pound blanking and progressive blanking.The pound blanking is that two or more than two processes are done in the same die position in one press progressive blanking is that several blanking processes are done at different die positions in one press workpicec can be produce in each press stroke but the initial stroke is the productivity of the pound blanking is higher than that of the single blanking,and the tolerance grade of workpiece of the pound blanking is also higher than that of the single blanking.The pound mode of the blanking process is determined by following factors:1) Production batch.Generally,the single blanking is suitable for small batch or trial production,the pound or progressive blanking is suitable for medium and large batch production.2) Dimension tolerance grade of the blanking workpiece.The tolerance grade of the workpiece produced through the pound blanking is high, because multitime locating error can be avoided in this pared with pound blanking, the tolerance grade of the workpiece produced through progressive blanking is low.3) Dimension and shape of the workpiece.When the dimension of the workpiece is small, the pound or progressive blanking is usually adopted in view of inconvenience and low productivity of the single workpiece of medium dimension,the bined blanking is also used because to manufacture several simple dies is more expensive than a bined die. But if the distance between the holes or between hole and edge is too small,it is better to use propressive blanking than pound and single blanking. So the progressive blanking can used to produce abnormal workpieces with plex shape and small width,and the blanking material thickness in progressive blanking is larger than that in pound blanking. The progressive blanking is restricted by the working table dimension of press and the number of proess,so the size of blanking workpiece cannot be too bi