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重 庆 理 工 大 学文 献 翻 译二级学院 应用技术学院 班 级 107214801 学生姓名 张尚军 学 号 27 外文原文 Design and thermal analysis of plastic injection mould S.H. Tang , Y.M. Kong, S.M. Sapuan, R. Samin, S. Sulaiman Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Received 3 September 2004; accepted 21 June 2005 Abstract This paper presents the design of a plastic injection mould for producing warpage testing specimen and performing thermal analysis for the mould to access on the effect of thermal residual stress in the mould. The technique, theory, methods as well as consideration needed in designing of plastic injection mould are presented. Design of mould was carried out using commercial computer aided design software Unigraphics, Version 13.0. The model for thermal residual stress analysis due to uneven cooling of the specimen was developed and solved using a commercial finite element analysis software called LUSAS Analyst, Version 13.5. The software provides contour plot of temperature distribution for the model and also temperature variation through the plastic injection molding cycle by plotting time response curves. The results show that shrinkage is likely to occur in the region near the cooling channels as compared to other regions. This uneven cooling effect at different regions of mould contributed to warpage. Keywords: Plastic Injection mould; Design; Thermal analysis 1. Introduction Plastic industry is one of the worlds fastest growing industries, ranked as one of the few billion-dollar industries. Almost every product that is used in daily life involves the usage of plastic and most of these products can be produced by plastic injection molding method 1. Plastic injection molding process is well known as the manufacturing process to create products with various shapes and complex geometry at low cost 2. The plastic injection molding process is a cyclic process. There are four significant stages in the process. These stages are filling, packing, cooling and ejection. The plastic injection molding process begins with feeding the resin and the appropriate additives from the hopper to the heating/injection system of the injection plastic injection molding machine 3. This is the “filling stage” in which the mould cavity is filled with hot polymer melt at injection temperature. After the cavity is filled, in the “packing stage”, additional polymer melt is packed into the cavity at a higher pressure to compensate the expected shrinkage as the polymer solidifies. This is followed by “cooling stage” where the mould is cooled until the part is sufficiently rigid to be ejected. The last step is the “ejection stage” in which the mould is opened and the part is ejected, after which the mould is closed again to begin the next cycle 4. The design and manufacture of injection molded polymeric parts with desired properties is a costly process dominated by empiricism, including the repeated modification of actual tooling. Among the task of mould design, designing the mould specific supplementary geometry, usually on the core side, is quite complicated by the inclusion of projection and depression 5. In order to design a mould, many important designing factors must be taken into consideration. These factors are mould size, number of cavity, cavity layouts, runner systems, gating systems, shrinkage and ejection system 6. In thermal analysis of the mould, the main objective is to analyze the effect of thermal residual stress or molded-in stresses on product dimension. Thermally induced stresses develop principally during the cooling stage of an injection molded part, mainly as a consequence of its low thermal conductivity and the difference in temperature between the molten resin and the mould. An uneven temperature field exists around product cavity during cooling 7. During cooling, location near the cooling channel experiences more cooling than location far away from the cooling channel. This different temperature causes the material to experience differential shrinkage causing thermal stresses. Significant thermal stress can cause warpage problem. Therefore, it is important to simulate the thermal residual stress field of the injection-molded part during the cooling stage 8. By understanding the characteristics of thermal stress distribution, deformation caused by the thermal residual stress can be predicted. In this paper the design of a plastic injection mould for producing warpage testing specimen and for performing thermal analysis for the mould to access on the effect of thermal residual stress in the mould is presented. 2. Methodology 2.1. Design of warpage testing specimen This section illustrates the design of the warpage testing specimen to be used in plastic injection mould. It is clear that warpage is the main problem that exists in product with thin shell feature. Therefore, the main purpose of the product development is to design a plastic part for determining the effective factors in the warpage problem of an injectionmoulded part with a thin shell. The warpage testing specimen is developed from thin shell plastics. The overall dimensions of the specimen were 120mmin length, 50mmin width and 1mmin thickness. The material used for producing the warpage testing specimen was acrylonitrile butadiene stylene (ABS) and the injection temperature, time and pressure were 210 C, 3 s and 60MPa, respectively. Fig. 1 shows the warpage testing specimen produced. 2.2. Design of plastic injection mould for warpage testing specimen This section describes the design aspects and other considerations involved in designing the mould to produce warpage testing specimen. The material used for producing the plastic injection mould for warpage testing specimen was AISI 1050 carbon steel. Fig. 1. Warpage testing specimen produced. Four design concepts had been considered in designing of the mould including: i. Three-plate mould (Concept 1) having two parting line with single cavity. Not applicable due to high cost. ii. Two-plate mould (Concept 2) having one parting line with single cavity without gating system. Not applicable due to low production quantity per injection. iii. Two-plate mould (Concept 3) having one parting line with double cavities with gating and ejection system. Not applicable as ejector pins might damage the product as the product is too thin. iv. Two-plate mould (Concept 4) having one parting line with double cavities with gating system, only used sprue puller act as ejector to avoid product damage during ejection. In designing of the mould for the warpage testing specimen, the fourth design concept had been applied. Various design considerations had been applied in the design. Firstly, the mouldwas designed based on the platen dimension of the plastic injection machine used (BOY 22D). There is a limitation of the machine, which is the maximum area of machine platen is given by the distance between two tie bars. The distance between tie bars of the machine is 254 mm. Therefore, the maximum width of the mould plate should not exceed this distance. Furthermore, 4mm space had been reserved between the two tie bars and the mould for mould setting-up and handling purposes. This gives the final maximum width of the mould as 250 mm. The standard mould base with 250mm250mmis employed. The mould base is fitted to the machine using Matex clamp at the upper right and lower left corner of the mould base or mould platen. Dimensions of other related mould plates are shown in Table 1. Table 1 Mould plates dimensions. The mould had been designed with clamping pressure having clamping force higher than the internal cavity force (reaction force) to avoid flashing from happening. Based on the dimensions provided by standard mould set, the width and the height of the core plate are 200 and 250 mm, respectively. These dimensions enabled design of two cavities on core plate to be placed horizontally as there is enough space while the cavity plate is left empty and it is only fixed with sprue bushing for the purpose of feeding molten plastics. Therefore, it is only one standard parting line was designed at the surface of the product. The product and the runner were released in a plane through the parting line during mould opening. Standard or side gate was designed for this mould. The gate is located between the runner and the product. The bottom land of the gate was designed to have 20 slanting and has only 0.5mm thickness for easy de-gating purpose. The gate was also designed to have 4mm width and 0.5mm thickness for the entrance of molten plastic. In the mould design, the parabolic cross section type of runner was selected as it has the advantage of simpler machining in one mould half only, which is the core plate in this case. However, this type of runner has disadvantages such as more heat loss and scrap compared with circular cross section type. This might cause the molten plastic to solidify faster. This problem was reduced by designing in such a way that the runner is short and has larger diameter, which is 6mm in diameter. It is important that the runner designed distributes material or molten plastic into cavities at the same time under the same pressure and with the same temperature. Due to this, the cavity layout had been designed in symmetrical form. Another design aspect that is taken into consideration was air vent design. The mating surface between the core plate and the cavity plate has very fine finishing in order to prevent flashing from taking place. However, this can cause air to trap in the cavity when the mould is closed and cause short shot or incomplete part. Sufficient air vent was designed to ensure that air trap can be released to avoid incomplete part from occurring. The cooling system was drilled along the length of the cavities and was located horizontally to the mould to allow even cooling. These cooling channels were drilled on both cavity and core plates. The cooling channels provided sufficient cooling of the mould in the case of turbulent flow. Fig. 2 shows cavity layout with air vents and cooling channels on core plate. Fig. 2. Cavity layout with air vents and cooling channels. In this mould design, the ejection system only consists of the ejector retainer plate, sprue puller and also the ejector plate. The sprue puller located at the center of core plate not only functions as the puller to hold the product in position when the mould is opened but it also acts as ejector to push the product out of the mould during ejection stage. No additional ejector is used or located at product cavities because the product produced is very thin, i.e. 1 mm. Additional ejector in the product cavity area might create hole and damage to the product during ejection. Finally, enough tolerance of dimensions is given consideration to compensate for shrinkage of materials. Fig. 3 shows 3D solid modeling as well as the wire frame modeling of the mould developed using Unigraphics. Fig. 3. 3D solid modeling and wireframe modeling of the mould. 3. Results and discussion 3.1. Results of product production and modification From the mould designed and fabricated, the warpage testing specimens produced have some defects during trial run. The defects are short shot, flashing and warpage. The short shot is subsequently eliminated by milling of additional air vents at corners of the cavities to allow air trapped to escape. Meanwhile, flashing was reduced by reducing the packing pressure of the machine. Warpage can be controlled by controlling various parameters such as the injection time, injection temperature and melting temperature. After these modifications, the mould produced high quality warpage testing specimen with low cost and required little finishing by de-gating. Fig. 4 shows modifications of the mould, which is machining of extra air vents that can eliminate short shot. Fig. 4. Extra air vents to avoid short shot. 3.2. Detail analysis of mould and product After the mould and products were developed, the analysis of mould and the product was carried out. In the plastic injection moulding process, molten ABS at 210 C is injected into the mould through the sprue bushing on the cavity plate and directed into the product cavity. After cooling takes place, the product is formed. One cycle of the product takes about 35 s including 20 s of cooling time. The material used for producing warpage testing specimen was ABS and the injection temperature, time and pressure were 210 C, 3 s and 60MPa respectively. The material selected for the mould was AISI 1050 carbon steel. Properties of these materials were important in determining temperature distribution in the mould carried out using finite element analysis. Table 2 shows the properties for ABS and AISI 1050 carbon steel. Table 2 Material properties for mould and product The critical part of analysis for mould is on the cavity and core plate because these are the place where the product is formed. Therefore, thermal analysis to study the temperature distribution and temperature at through different times are performed using commercial finite element analysis software called LUSAS Analyst, Version 13.5. A two-dimensional (2D) thermal analysis is carried out for to study the effect of thermal residual stress on the mould at different regions. Due to symmetry, the thermal analysis was performed by modeling only the top half of the vertical cross section or side view of both the cavity and core plate that were clamped together during injection. Fig. 5 shows the model of thermal analysis analyzed with irregular meshing. Modeling for the model also involves assigning properties and process or cycle time to the model. This allowed the finite element solver to analyze the mould modeled and plot time response graphs to show temperature variation over a certain duration and at different regions. For the product analysis, a two dimensional tensile stress analysis was carried using LUSAS Analyst, Version 13.5. Basically the product was loaded in tension on one end while the other end is clamped. Load increments were applied until the model reaches plasticity. Fig. 6 shows loaded model of the analysis. Fig. 5. Model for thermal analysis. Fig. 6. Loaded model for analysis of product. 3.3. Result and discussion for mould and product analysis For mould analysis, the thermal distribution at different time intervals was observed. Fig. 7 shows the 2D analysis contour plots of thermal or heat distribution at different timeintervals in one complete cycle of plastic injection molding. Fig. 7. Contour plots of heat distribution at different time intervals. For the 2D analysis of the mould, time response graphs are plotted to analyze the effect of thermal residual stress on the products. Fig. 8 shows nodes selected for plotting time response graphs. Figs. 917 show temperature distribution curves for different nodes as indicated in Fig. 8. From the temperature distribution graphs plotted in Figs. 917, it is clear that every node selected for the graph plotted experiencing increased in temperature, i.e. from the ambient temperature to a certain temperature higher than the ambient temperature and then remained constant at this temperature for a certain period of time. This increase in temperature was caused by the injection of molten plastic into the cavity of the product. After a certain period of time, the temperature is then further increased to achieve the highest temperature and remained constant at that temperature. Increase in temperature was due to packing stages that involved high pressure, which caused the temperature to increase. This temperature remains constant until the cooling stage starts, which causes reduction in mould temperature to a lower value and remains at this value. The graphs plotted were not smooth due to the absence of function of inputting filling rate of the molten plastic as well as the cooling rate of the coolant. The graphs plotted only show maximum value of temperature that can be achieved in the cycle. The most critical stage in the thermal residual stress analysis is during the cooling stage. This is because the cooling stage causes the material to cool from above to below the glass transition temperature. The material experiences differential shrinkage that causes thermal stress that might result in warpage. From the temperature after the cooling stage as shown in Figs. 917, it is clear that the area (node) located near the cooling channel experienced more cooling effect due to further decreasing in temperature and the region away from the cooling channel experienced less cooling effect. More cooling effect with quite fast cooling rate means more shrinkage is occurring at the region. However, the farthest region , Node 284 experience more cooling although far away from cooling channel due to heat loss to environment. Fig. 8. Selected nodals near product region for time response graph plots. Fig. 9. Temperature distribution graph for Node 284. Fig. 10. Temperature distribution graph for Node 213. Fig. 11. Temperature distribution graph for Node 302. Fig. 12. Temperature distribution graph for Node 290. Fig. 13. Temperature distribution graph for Node 278. Fig. 14. Temperature distribution graph for Node 1838. Fig. 15. Temperature distribution graph for Node 1904. Fig. 16. Temperature distribution graph for Node 1853. Fig. 17. Temperature distribution graph for Node 1866. As a result, the cooling channel located at the center of the product cavity caused the temperature difference around the middle of the part higher than other locations. Compressive stress was developed at the middle area of the part due to more shrinkage and caused warpage due to uneven shrinkage that happened. However, the temperature differences after cooling for different nodes are small and the warpage effect is not very significant. It is important for a designer to design a mould that has less thermal residual stress effect with efficient cooling system. For the product analysis, from the steps being carried out to analyze the plastic injection product, the stress distribution on product at different load factor is observed in the two dimensional analysis. A critical point, Node 127, where the product experiences maximum tensile stress was selected for analysis. From the load case versus stress curves at this point plotted in Fig. 23, it is clear that the product experiencing increased in tensile load until it reached the load factor of 23, which is 1150 N. This means that the product can withstand tensile load until 1150 N. Load higher than this value causes failure to the product. Based on Fig. 23, the failure is likely to occur at the region near to the fixed end of the product with maximum stress of 3.27107 Pa. The product stress analysis reveals very limited information since the product produced was for warpage testing purposes and had no relation with tensile loading analysis. In future, however, it is suggested that the product service condition should be determined so that further analysis may be carried out for other behaviors under various other loading. that affect warpage. The testing specimen was produced atlow cost and involves only little finishing that is de-gating. The thermal analysis of plastic injection mould has provided an understanding of the effect of thermal residual stress on deformed shape of the specimen and the tensile stress analysis of product managed to predict the tensile load that the warpage testing specimen can withstand before experiencing failure. Acknowledgement The authors wish to thank the Faculty of Engineering, Universiti Putra Malaysia for initiating the publication of this paper. References 1 R.J. Crawford, Rubber and Plastic Engineering Design and Application, Applied Publisher Ltd., 1987, p. 110. 2 B.H. Min, A study on quality monitoring of injection-molded parts, J. Mater. Process. Technol. 136 (2002) 1. 3 K.F. Pun, I.K. Hui, W.G. Lewis, H.C.W. Lau, A multiple-criteria environmental impact assessment for the plastic injection molding process: a methodology, J. Cleaner Prod. 11 (2002) 41. 4 A.T. Bozdana, O . Eyercoglu, Development of an Expert System for the Determination of Injection Moulding Parameters of Thermoplastic Materials: EX-PIMM, J. Mater. Process. Technol. 128 (2002) 113. 5 M.R. Cutkosky, J.M. Tenenbaum, CAD/CAM Integration Through Concurrent Process and Product Design, Longman. Eng. Ltd., 1987, p. 83. 6 G. Menges, P. Mohren, How to Make Injection Molds, second ed., Hanser Publishers, New York, 1993, p 129. 7 K.H. Huebner, E.A. Thornton, T.G. Byrom, The Finite Element Method for Engineers, fourth ed., Wisley, 2001, p. 1. 8 X. Chen, Y.C. Lam, D.Q. Li, Analysis of thermal residual stress in plastic injection molding, J. Mater. Process. Technol. 101 (1999) 275. 翻译文章 塑料注射模具设计及其热分析 摘要 本文主要介绍一个生产翘曲测试样件的注射模具设计并进行热分析以助于了解残余热应力对模具的影响。提出了设计塑料注射模具所需的技术、理论、方法以及其它一些考虑因素。模具的设计部分可以利用装在一般的商业电脑上的设计软件Unigrafics，版本13.0来完成。对于由样本的不均匀冷却引起残余热应力的模拟已经逐步发展起来，并可以用一个商业的有限元分析软件LUSAS Analyst, 版本13.5进行模拟。这个软件用轮廓绘图模拟温度分布情况以及绘制时间响应曲线来表现在塑料注射模制模周期内的温度变动情况。结果显示，相对与其它区域来说冷却通道旁边的区域比较容易产生收缩。这种在模具不同区域不均匀冷却就表现为翘曲。 关键词 塑料注射模具 设计 热分析 1. 简介 塑料行业是世界上发展最快的行业之一，属于少数亿万美圆的行业。在日常生活中几乎所有的用品都离不开塑料并且大部分都可以用用塑料注射模具的方法生产1。注塑注射成型工艺也以利用低成本制作出各种各样的形状及复杂的几何图案著称2。 注塑注射成型工艺是一个循环过程。可分为填料、注射、冷却、脱模四个重要阶段。塑料注射成型过程开始于往料斗到注塑机的加热或注射系统中填入树脂和适量的添加剂3。灌浆阶段就是在注射温度下用融解的热塑料注入模腔。模腔被填满之后，适量的熔融塑料在一个较高的补偿压力下补充塑料凝固引起的收缩。跟着是冷却阶段，将模具冷却至有足够的刚度脱出模具。最后是脱模阶段，即打开模具然后顶出零件，再合上模具开始下一个循环4。 需要注塑成型的塑料产品的设计和制造与预期性能是要靠经验控制的一个昂贵的过程，包括实际对封面压花的修改。在模具设计之中，设计模具具体补充几何，通常在核心边，包括相当复杂的投射和凹槽5。 设计模具时必须考虑到许多重要设计系数。这些因素是模具的大小，型腔的个数及布局、流道系统，浇口系统、脱模系统和收缩率6。 对模具的热分析，主要宗旨将分析残余热应力的作用或产品直径方向的压注。热感应强度的增强主要在模塑零件的冷却阶段，主要因为它的低导热性和在溶融树脂和模具之间的温差。在冷却期间产品模腔附近也会存在温度不均匀的区域 7。 在冷却期间，冷却通道附近的区域比冷却通道远处的区域冷却得更快。这个温差会造成材料的不均匀收缩从而产生热应力。强热应力会引起翘曲问题。所以，它是模仿模塑零件在冷却期间残余热应力区域的重要阶段8。通过了解热应力发生的特征，对其造成的变形可以预先模拟。 在本文中注塑模的设计是为了产生翘曲的测试样本和能对呈现在模具上残余热应力的作用执行热分析。 2. 操作方法 2.1. 翘曲测试标本的设计 这个部分说明用于注塑模的翘曲测试的标本设计。它表明翘曲是存在于薄壁产品的主要问题。所以，产品开发的主要目的在于控制能影响薄壁注塑零件翘曲问题的有效的因素。 翘曲测试样本是薄壁注塑零件。样本的总体尺寸是长120mm、宽50mm、厚1mm。为导致翘曲，测试标本所用的材料是丙烯腈丁邻二烯 (ABS)，射入温度、时间和压力分别为210， 3 s和60MPa。图1显示翘曲测试样本。 图1翘曲测试样本 2.2. 为翘曲测试样本设计注塑模具 这个部分描述在设计模具和介入设计的其他考虑因素方面导致翘曲的测试样本。用于生产翘曲测试样本注塑模具的材料是AISI 1050碳钢。在设计模具时可以考虑以下四种类型： i. 三板模（类型1）一个型腔两条分型线。费用较高，不适用。 ii. 二板模（类型2）一个型腔一条分型线，没有浇注系统。每次生产数量少，不适用。 iii. 二板模（类型3）两个型腔一条分型线，带有浇注和脱模系统。如果零件太薄有可能会被顶杆推破，不适用。 iv. 二板模（类型4）两个型腔一条分型线，利用直浇口脱模以避免损坏零件。 在为翘曲测试样本设计模具时宜选用第四种类型。设计时还有许多因素需要考虑。 首先，模具的设计基于选用的注塑机的压板尺寸。压板的最大区域取决于两系杆之间的距离，这对于注塑机来说是一个限制。这里用的注塑机的两系杆距离为254mm。所以模具板材的最大宽度不能超过这个距离。此外，还有4mm的空间留在系杆和模具之间以便模具的拆装。这使模具的最大尺寸为250mm，可采用 标准模具基体。并在模具基体的右上角和左下角用卡钉固定在压板上。其他相关模板的尺寸见表1。 表1 各模板尺寸 零件 尺寸（mm）长 宽 高 顶部压紧板 母模板 公模板 侧板/底版 推杆固定板 推板 动模座板 25025025 20025040 20025040 3725070 12025015 12025020 25025025 模具必须与夹压力一同设计让夹紧力比模腔内作用力力更高 (反应力) 从而避免塑料喷溅的发生。 根据标准模具提供的尺寸，公模板的宽和高分别为200mm和250mm。这些尺寸使水平地被安置的公模板上有足够的空间来设计双模腔，而母模板只需留有固定浇口套的空间以便注入溶融塑料。所以，在产品的表面只会留下一条分型线的痕迹。在开模时产品和流道将在分型面同时脱落。 这套模具的浇口形式是标准浇口或侧浇口。浇口是位于流道和产品之间的。浇口的底部被设计成只有0.5mm厚并有20的斜度目的是为了更容易注入塑料。浇口的另一头也就是溶融塑料注入的一侧则有4mm宽0.5mm厚。 设计这个模具时，选用了截面为抛物面形式的流道，可以只在公模板上方便的加工。但是，这种形式的流道与圆形流道相比有更多的热量损失和废料。这可能使熔融塑料冷却过快。所以在设计时应使流道比较短且至少要有6mm的径向尺寸。 材料或熔融塑料在同一温度同一压力下同时被送到个模腔对于流道设计来说是很重要的一点。基于这点，模腔的布局一般都是对称的。 另外，气孔的设计也是模具设计中一个重要的方面。公模板和母模板的配合表面有很高的加工精度以防止注塑时泄露的发生。但是，这会使空气被封闭在闭合模腔内从而导致短射或使零件不完整。合适起气孔设计可以使空气释放出来不会出现零件不完整的现象。 冷却系统是沿模腔长度方向在模具上打出的水平孔，只起冷却作用。在湍流情况下，水线可以充分冷却模具。图2显示了在公模板上气孔、水线以及模腔的布局。 图2 在公模板上气孔、水线以及模腔的布局 在这个设计中，脱模系统只有推杆固定板、浇口套和推板。交口套的位于公模的中心，它的作用不仅是将产品固定在合适位置，在开模是还起到将产品拉出模腔的作用。因为产品非常薄，通常为1mm，所以不需要设计其附加的推杆。模腔里的推杆反而有可能在脱模的时候在零件上推出破孔。 最后，还要根据材料的收缩率留出足够的公差补偿。 图3所示的是用Unigraphics设计的模具三维模型以及线框模型。 图3 模具的三维实体模型和线框模型 3. 结果与讨论 3.1. 产品的生产及改良 模具的设计和制造完成后，试模注塑出来的翘曲试样会存在很多缺陷。包括短射、喷溅和翘曲。短射的解决可以通过在模腔的角落里铣出附加的气孔来排出被困的空气。同时，减小注射压力可以减小喷溅的发生。对于翘曲的控制可以通过控制很多因素，例如注射时间、注射温度和溶料温度。 经过这些修整之后，模具可以生产出低成本高质量的翘曲试样，这些试样需要经过简单的抛光处理。图4显示的是修整后的模具，加工出附加的排气孔可避免短射现象的发生。 图4 附加气孔以避免短射 3.2. 模具及产品的详细分析 模具和试样都准备好之后，就可以对其进行分析了。在注塑的过程中，210熔融的ABS通过母模上的浇口套直接注入模腔，经过冷却，制件就成型了。制件的生产周期为35s，包括20s的冷却时间。用来制造模具的材料是AISI 1050碳钢。表2列出了ABS以及AISI 1050碳钢的性能。 表2 ABS以及AISI 1050碳钢的性能 模具，AISI 1050碳钢 试样，ABS 密度 7860 kg/m3 弹性模量 208 GPa 泊松比 0.297 屈服强度 365.4MPa 抗拉强度 636MPa 热膨胀率 65106 K1 电导率 0.135 W/(m K) 比热 1250 J/(kg K) 1050 kg/m3 2.519 GPa 0.4 65MPa 11.65106 K1 49.4 W/(m K) 477 J/(kg K) 由于对称，在注塑过程中只需对公模和母模垂直截面的上半部分进行热分析。图5所示的是多层模板闭合的热分析模型。 建模包括分配各部分的性能以及模型的循环周期。这样可以用有限元分析软件用造型模拟模
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