After more than half a century, China's plastic mold industry has made great progress and the mold level has been greatly improved. In terms of large-scale molds, it has been able to produce injection molds for plastic casings of 48-inch large-screen color TVs, complete sets of plastic molds for 6.5kg large-capacity washing machines, automobile bumpers, integral dashboards and other plastic molds; Precision plastic molds have been able to produce camera plastic parts molds, multi-cavity small module gear molds and plastic packaging molds. For example, the multi-cavity VCD and DVD gear molds produced by Tianjin Jin Rong Tianhe Electromechanical Co., Ltd. and Yantai Polaris I.K Mould Co., Ltd. have reached the level of similar foreign products in terms of dimensional accuracy, coaxiality and runout, and adopted the latest gear design software to correct the tooth profile error caused by molding shrinkage and meet the requirements of standard involute tooth profile. 1. Improve the design and manufacturing level and proportion of large, precise, complex and long-life molds. This is due to the increasingly large-scale, complex and high-precision requirements for plastic molding products, as well as the development of multi-cavity for high productivity requirements. 2. Fully popularize and apply CAD/CAM/CAE technology in the design and manufacture of plastic molds. CAD/CAM technology has developed into a mature technology. In recent years, the price of software and hardware of mold CAD/CAM technology has been reduced to a level generally acceptable to small and medium-sized enterprises, which has created favorable conditions for its further promotion. The integrated architecture of CAD/CAM/CAE based on network has begun to take shape, which will solve the problem that the traditional hybrid CAD/CAM system can not meet the requirements of division of labor and cooperation in the actual production process. The intelligent degree of CAD/CAM software will be gradually improved; Three-dimensional design of plastic parts and molds and three-dimensional analysis of molding process will play an increasingly important role in China plastic mold industry.
3. Popularize and apply hot runner technology, gas-assisted injection molding technology and high-pressure injection molding technology. The mold with hot runner technology can improve productivity and product quality, and can greatly save raw materials and energy of plastic products, so the wide application of this technology is a major reform of plastic molds. It is the key to develop hot runner molds to formulate national standards for hot runner parts and actively produce low-cost and high-quality parts. Gas-assisted injection molding can greatly reduce the cost on the premise of ensuring product quality. At present, it is being gradually popularized and used in the automobile and home appliance industries. Compared with the traditional common injection process, gas-assisted injection molding has more process parameters to be determined and controlled, and it is mostly used for complex large-scale products, so it is difficult to design and control the mold. Therefore, it is very important to develop flow analysis software for gas-assisted injection molding. On the other hand, in order to ensure the accuracy of plastic parts, it is also very important to continue to study and develop high-pressure injection molding technology and mold, as well as injection compression molding technology and mold. 4. Develop new plastic molding technology and quick and economical molds. In order to adapt to the production mode of multi-variety and small batch. 5. Improve the standardization level of plastic molds and the utilization rate of standard parts. The standard level and standardization degree of China's molds are still low, and there is a big gap with foreign countries, which restricts the development of China's mold industry to some extent. In order to improve mold quality and reduce mold manufacturing cost, we should vigorously promote the application of mold standard parts. To this end, we must first formulate a unified national standard and produce in strict accordance with the standard; Secondly, it is necessary to gradually form large-scale production, improve the degree of commercialization, improve the quality of standard parts and reduce costs; Thirdly, it is necessary to further increase the specifications and varieties of standard parts. 6. High-quality mold materials and advanced surface treatment technology must be applied to improve the life and quality of the mold. 7. Research and apply high-speed measurement technology and reverse engineering of molds. It is one of the key technologies of plastic mold CAD/CAM to realize reverse engineering by using three-coordinate measuring instrument or three-coordinate scanner. The research and application of diverse, adjustable and cheap test equipment is a necessary prerequisite to realize reverse engineering. Since the reform and opening up, with the rapid development of the national economy, the market demand for molds has been increasing. In recent years, the mold industry has developed rapidly with a growth rate of about 15%, and the equity composition of mold industry enterprises has also undergone tremendous changes. In addition to state-owned professional mold factories, collective, joint venture, sole proprietorship and private enterprises have also developed rapidly. Zhejiang Ningbo, Huangyan's hometown of molds; Some large group companies and rapidly rising township enterprises in Guangdong, Kelon, Midea, Konka and other groups have established their own mold manufacturing centers; There are thousands of Sino-foreign joint ventures and wholly foreign-owned mold enterprises.
In recent years, many mold enterprises have increased their investment in technological progress, which is regarded as an important driving force for enterprise development. Some domestic mold enterprises popularized 2D CAD and began to use international general software such as UG, Pro/E, I-DEAS and Euclid-IS. Some manufacturers also introduced CAE software such as Moldflow, C-Flow, DYNAFORM, Optris, MAGMASOFT, etc., and successfully applied them to the design of stamping dies. The manufacturing technology of large stamping dies such as automobile panel dies has made great progress. The mold factories of Dongfeng Motor Corporation and FAW Mold Center have been able to produce some auto panel molds. In addition, many research institutions and universities carry out research and development of mold technology. After years of efforts, the technology of mold CAD/CAE/CAM has made remarkable progress. It has made great contributions to improve the quality of mold and shorten the design cycle of mold. For example, KMAS software for auto panel stamping analysis independently developed by auto panel forming technology of Jilin University, CAD/CAE/CAM software for injection mold and auto panel mold developed by State Key Laboratory of Mold Technology of Huazhong University of Science and Technology, cold stamping mold developed by National Engineering Research Center of Mold CAD of Shanghai Jiaotong University, cold stamping mold and fine stamping mold CAD software developed by Fine Stamping Research Center, etc., have many users in the domestic mold industry. Although China's mold industry has made remarkable progress in the past ten years, there is still a big gap compared with developed countries in many aspects. For example, the proportion of precision machining equipment in mold machining equipment is relatively low; The popularization of CAD/CAE/CAM technology is not high; Many advanced mold technologies have not been widely used, so a considerable number of large, precise, complex and long-life molds depend on imports. In the future development of mold industry, we should pay more attention to the strategic adjustment of its product structure, so that high-grade molds with complex structure and high precision can develop faster. Our mold industry should keep up with the market demand. Without product demand and product upgrade, there will be no technological progress in the mold industry, and there will be no scale and grade of mold products. For example, more than 90% parts in automobile production depend on mold forming. In the Pearl River Delta and the Yangtze River Delta, the output value of molds supporting the automobile industry has increased by about 40%. The level of mold technology largely determines the quality, benefit and development ability of new products. It has become an important symbol to measure a country's product manufacturing level. We should actively promote the development of mold industry in the central and western regions and strive to narrow the gap between developed and underdeveloped regions. Many areas in the central and western regions have realized the important role of the development of mold industry in manufacturing industry. For example, the mold production in Shaanxi, Sichuan and Hebei has made great progress. As the backbone enterprise in Botou area of Hebei Province, Hebei Xinglin Body Manufacturing Group Co., Ltd. has promoted the development of a mold enterprise. Sichuan Yibin Pushi Mould Co., Ltd. will write a new chapter in the future with its abundant capital investment. We should actively promote the institutional innovation of mold enterprises, especially state-owned enterprises, change the operating mechanism, vigorously develop the mixed ownership economy, clarify property rights and improve the corporate governance structure. Fully tap the internal motivation of enterprise development. It is necessary to actively promote the separation of large and medium-sized manufacturing enterprises in areas with good industrial base in the central and western regions, so that their mold workshops and branches can adopt various effective realization forms and conversion mechanisms in a short time, vigorously develop modern professional mold enterprises with clear property rights, independent operation, adaptation to market operation and rapid response to mold production, and cultivate "leading" enterprises that can represent the industry level and promote the development of regional industrial chains.
Chapter 1 Task Source and Significance of Design Purpose 1. 1 Design Task Source Design Title: Plastic sleeve material: PA production batch: technical requirements for mass production: ① No rounded corners R0.5② All dimensional tolerances shall conform to SJ 1372-78 four-level precision drawing1product parts drawing. The design requirements, content and direction of plastic parts of box cover are summarized. Through the mold design of this part, the foundation of designer's injection mold design is further consolidated, paving the way for designing more complicated injection mold and drawing more profound experience. Chapter 2: Process Analysis of Parts 2. 1 Process Analysis of Plastic Parts (1) Raw Material Analysis of Plastic Parts: Raw Material Analysis of Plastic Parts. Plastic parts are made of nylon 6(PA6) and belong to thermoplastic plastics. From the performance, the plastic has good mechanical strength and stiffness, excellent toughness, self-lubrication, wear resistance and good chemical resistance. It also has the advantages of non-toxicity and easy coloring. (1) low melt viscosity, good fluidity and easy flash (flash gap is 0.02 mm) (2) Plastic is easy to absorb moisture, so it should be preheated and dried before molding, and moisture absorption should be prevented after drying, and the water content during molding should not exceed 0.3%. Otherwise, the liquidity will decrease. Products are prone to defects such as bubbles and silver wires. For parts with high precision, it is necessary to adjust humidity after molding, and the product size will expand after adjusting humidity. [1]③. The plastic shrinkage rate is unstable (the shrinkage rate is 1.5 ~ 2.5%) [2] ④. The cooling rate of plastic melt has a great influence on the crystallinity and product performance. The mold temperature range (20 ~ 90℃) should be correctly selected and controlled according to the product wall thickness, which is prone to shrinkage and crystallization problems. 2.2 Analysis of structure and dimensional accuracy and surface quality of plastic parts 2.2. 1 structural analysis ① structural analysis. According to the analysis of the part drawing, the overall shape of the part is only 6 mm in the height direction and 30mm in the length direction. And there is a small outer core-pulling inside the inner wall of the lower end, so the core-pulling space is small and the mold design and manufacture are difficult. 2.2.2 Analysis of dimensional accuracy What are the important dimensions of this part? 、? 、? And the dimensional accuracy is MT2 (GB/T14486-1993). What is the next most important dimension? 、? The equal dimensional accuracy is MT3 (GB/T14486-1993). According to the above analysis, the dimensional accuracy of this part is above the average level, which can ensure the dimensional processing of die-related parts. Judging from the wall thickness of plastic parts, the wall thickness is relatively uniform, which is beneficial to the molding of plastic parts.
Judging from the wall thickness of plastic parts, all the wall thickness dimensions are 3mm, and the wall thickness is uniform, which is beneficial to the molding of plastic parts. 2.2.3 Surface quality analysis The surface of this part has no special surface quality requirements except defects and burrs, which is easy to realize. To sum up, it can be seen that controlling the process parameters during injection molding can ensure the molding requirements of parts. 2.3 Calculating the volume and quality of plastic parts The purpose of calculating the quality of plastic parts is to select injection molding machines and determine the number of cavities of the molds. Calculate the volume of plastic parts: V= 1955.68? (Process omitted) Calculating the quality of plastic parts: According to the design manual, the density of PA is ρ= 1. 12g/? Therefore, the quality of plastic parts is: w = v ρ =1955.68×1.12×? =2. 19g adopts the mold structure of 16 cavity. Considering the overall size, LY80 injection molding machine was selected initially. The injection volume of the injection molding machine is 1 16g, the injection pressure is 230mpa, and the clamping force is 800KN. The maximum mold opening stroke is 280mm, the maximum installation size is 350mm×350mm, the mold loading height is 150 mm ~ 350 mm, and the ejection stroke is100 mm. [3] Chapter III Determination of plastic molding characteristics and process parameters, refer to the actual application in the factory, and the PA molding process parameters can be selected as follows (the mold can be adjusted appropriately according to the actual situation) for injection. Choose the late temperature of 70℃? What is the intermediate temperature of 240℃? Choose the temperature before 250℃? Select 250℃ nozzle temperature Select 250℃ melt temperature: 240 ~ 250℃ barrel constant temperature: 220℃ mold temperature: 60 ~ 100℃ injection pressure:160 MPa injection time: select 0.1.
Injection speed: it is recommended to measure the stroke with a faster injection speed: 0.5~3.5D residual material: 4mm preheating rod: 80℃ drying for 4 hours; recovery rate: 10% return shrinkage rate: 0.7% ~ 2.0%; gate system: downtime of dispensing machine: no need to clean with other materials, and molten materials can stay in the barrel for 20 minutes. It is easily thermally degraded. Note: The machine barrel is equipped with standard screw, with special geometric size and high plasticizing capacity. The above can be used for straight-through nozzles. [4] Chapter IV Design of Gating System 4. 1 Selection of parting surface The plastic part is a plastic cover, which has no special requirements for surface quality, but it often contacts with people's hands when it is rotated externally. Therefore, the upper end surface is preferably naturally circular. In addition, the height of this part is 6mm, and it is matched with another workpiece. Therefore, it is necessary to ensure the coaxiality of the lower mating parts, that is, to place them on the same side of the mold cavity. Therefore, it is reasonable to choose the following parting surface. Fig. 3- 1 parting surface 4.2 molding position of plastic parts: when injecting 16 pieces, it needs 16 cavities. Considering the complexity of the gating system mold structure and other factors, the following cavity layout is planned: Figure 3-3 The biggest advantage of using the cavity layout shown in the above figure is that the length and size of the branch channels from the end of the main channel to each cavity are equal. Therefore, the stress of each runner is relatively balanced, which is easy to form plastic parts. Considering the arrangement of mold cavities and the external dimensions of plastic parts, what is the standard mold base type? —250×3 15—T—？ Gb/t 1 2556.1-19904.3 design of main runner (1) According to the design manual, the relevant dimensions of the injection molding machine nozzle of LY80 are found: the aperture of the front end of the nozzle? = Ф 4.8 mm nozzle front spherical radius? = 12.6mm according to the relationship between the main runner and the nozzle of the mold, R=? +( 1~2)mmD=？ +(0.5 ~ 1) mm take the spherical radius of the main groove R= 13.5mm take the diameter of the small end of the main groove d = Ф 5 mm In order to pull out the concrete from the main groove, the main groove is designed with a slope of? ~? After conversion, it is found that the diameter of the big end of the main channel is d = Ф 8.5 mm. In order to make the melt enter the splitter smoothly, an arc transition with a radius of r=5mm can be designed at the discharge end of the main channel.
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Design of injection mold for plastic cover
Design of injection mold for plastic cover
Thread theory
Objective: To design a plastic mold which can produce a given plastic part, has a reasonable structure and can ensure the product precision and surface quality. Proficient in using PRO/E, AUTOCAD and other three-dimensional CAD CAD and CAM drawing software.
Significance: With the wide application of plastic products in machinery, electronics, transportation, national defense, construction, agriculture and other industries, the demand for plastic molds is increasing, and the importance of plastic molds in the national economy is becoming increasingly prominent. As a high value-added and technology-intensive product, the technical level of molds has become one of the important symbols of a country's manufacturing level. The main design significance of this project lies in mastering the general idea of injection mold design, knowing how to analyze and consider problems, and being able to independently design a set of molds and apply them to actual production.