塑料薄膜吹塑过程膜泡的冷却技术

在塑料薄膜吹塑过程中 ,风环、膜泡内冷系统是膜泡成型、冷却的重要构件 ,膜泡的冷却依靠风环、膜泡内冷系统及吹塑设备周围的环境温度 (室温 )。风环是吹塑工艺膜泡成型和冷却必不可少的基础部件 ,膜泡周围柔和的气流和合适的环境温度是膜泡后冷却的基本条件。膜泡内冷是一种先进的膜泡辅助成型和加速膜泡冷却的新技术。吹塑薄膜的冷却原理 :塑料薄膜吹塑过程采用以空气作为冷却介质的风环对膜泡的吹胀区 (即口模到冷凝线之间 )进行外冷却 ,当冷却空气通过风机经风环以一定的角度和速度吹向刚从机头挤出塑料膜管时 ,高温的膜泡与冷却空气相…     

热虹吸油冷却系统：系统安装篇

从热虹吸油冷却系统的正确安装方式入手,结合实践经验,剖析十几种常见的错误安装方式,并分析热虹吸油冷却系统对制冷系统的负面影响,最后给出大型热虹吸油冷却系统的安装建议,进一步提高热虹吸油冷却系统的整体应用水平。     

新型气冷吹塑聚丙烯薄膜原料

聚丙烯吹塑薄膜传统上采用水冷却法生产。薄膜膜泡通过向下吹塑以及用流动冷水触动膜泡外层以实现冷却成形。     

塑料薄膜吹塑过程膜泡的冷却技术

叙述吹塑膜泡冷却的工作原理及冷却技术，阐明膜泡冷却装置和机头对薄膜厚薄误差的关系，分析不同的膜泡冷却装置的技术性能。     

新型气冷吹塑聚丙烯薄膜原料

聚丙烯吹塑薄膜传统上采用水冷却法生产。薄膜膜泡通过向下吹塑以及用流动冷水触动膜泡外层以实现冷却成形。     

CPU液体冷却器件及冷却液材料研究进展

综述了目前关于计算机CPU散热的3种液体冷却系统(大器件液冷循环系统、热管冷却系统和液体喷射冷却系统)及所采用的多种冷却液(水、液态金属和纳米流体)的研究进展;比较了3种液冷器件和3种冷却液的优缺点,指出热管冷却系统和纳米流体更加具有竞争优势;最后展望了CPU冷却器件和冷却液的发展前景。     

智能新风净化冷却系统在中小型数据中心的应用

简述新风直接冷却和间接冷却技术的应用原理。通过与传统压缩制冷系统的对比，说明采用智能新风净化冷却系统可降低耗电量23.2%。最后分析智能新风净化冷却系统在小型数据中心领域应用的前景。     

氨制冷系统热虹吸冷却技术

阐述了沸腾高压氨液作冷却液的热虹吸环流间接冷却的原理,介绍分析了带热虹吸贮液器的典型热虹吸油冷却系统、带卧式贮液器的热虹吸油冷却系统、多台油冷却器的热虹吸冷却系统的流程,以及热虹吸油冷却系统的设计。     

捷达发动机冷却系统的结构与工作原理

本文是介绍并研究捷达王发动机冷却系统的文章,目的是使我们更深的了解捷达王发动机冷却系统的结构、原理、以及工作过程。     

TX1800磁控溅射镀膜机冷却系统的改进

本文以北京天瑞星公司生产的大型TX 1800商用磁控溅射镀膜机为例,简要分析了此磁控溅射镀膜机中靶的结构及配套冷却系统,引入航空航天领域应用较多的层板发汗冷却在此基础上,提出了一种全新的思路,对冷却系统进行了重新设计.     

基于滑模控制的低压铸造模具冷却控制系统设计

目的 为了准确控制模具的温度,提高铸件品质和效率.方法 设计基于滑模控制的模具冷却控制系统.首先,以低压铸造模具冷却工艺为基础,分析不同模具温度对铸件品质的影响,明确模具温度控制的重要性.基于浇注温度、冷却水温度以及模具温度,对模具冷却过程进行建模,获取冷却水和模具的热传递函数.然后,采用三向(左、右、底部)冷却方法,...     

Heating/cooling channels design for an automotive interior part and its evaluation in rapid heat cycle molding

Rapid heat cycle molding (RHCM) is a recently developed innovative injection molding technology. Rapid heating and cooling of the injection mold is the most crucial technique in RHCM because it not only has a significant effect on part quality but also has direct influence on productivity and cost-efficiency. Accordingly, Heating and cooling system design plays a very important role in RHCM mold design. This study focuses on the heating/cooling system design for a three-dimensional complex-shaped automotive interior part. Heat transfer simulation based on finite element analysis (FEA) was conducted to evaluate the thermal response of the injection mold and thereby improve heating/cooling channels design. Baffles were introduced for heating/cooling channels to improve heating/cooling efficiency and uniformity of the mold. A series of thermal response experiments based on full factorial experimental design were conducted to verify the effectiveness of the improved heating/cooling channels design with baffles. A mathematical model was developed by regression analysis to predict the thermal response of the injection mold. The effects of the cavity surface temperature on weld mark and surface gloss of the part were investigated by experiments. The results show that the developed baffle-based heating/cooling channels can greatly improve thermal response efficiency and uniformity of the mold. The developed mathematical model supplies an efficient approach for precise predication of mold thermal response. As the cavity surface temperature raises to a high enough level, automotive interior parts with high gloss and non-weld mark surface can be obtained.     

注塑成型冷却过程的数值模拟

采用循环平均假设，忽略模壁温度的周期变化，将模具的传热简化为三维稳态热传导总是，考虑到注射模的结构特点（型腔为狭缝面，冷却孔细长），推导出求解其温度场的边界积分方程；注塑件的传热简化为一维瞬态热传导，给出确定其冷却时间及表面循环平均热流的方法；通过模具及塑件传热的耦合迭代分析，使模具－塑料件界面的温度和热流满足相容条件，最终确定模具型腔的温度分布及塑件的冷却时间。最后通过一个例子说明数值模拟在冷却系统设计中的应用。     

THREE-DIMENSIONAL TRANSIENT MOLD COOLING ANALYSIS BASED ON GALERKIN FINITE ELEMENT FORMULATION WITH A MATRIX-FREE CONJUGATE GRADIENT TECHNIQUE

A methodology is presented to simulate the three-dimensional heat transfer within a mold during the injection molding process. The mold cooling analysis assists cooling channel design and paves the way for part shrinkage and warpage analysis. The transient temperature distributions in the mold and the polymer part are simultaneously computed by Galerkin Finite Element Method (GFEM) using a matrix-free Jacobi Conjugate Gradient (JCG) scheme. The numerical method presented here is efficient and has shown to require a fraction of the memory and computing time required by conventional methods. The matrix-free algorithm is initially validated using an injection mold designed to produce a plaque with a molded-in hole. Subsequently, the method is further applied to a representative automotive plastic component.     

接触热阻对注塑制品冷却时间的影响

从塑件的瞬态热传导方程出发，推导出了存在在接触热阻时塑件的温度分布吸冷却时间计算的解析表达式，并通过几个简单例子讨论了接触热阻对冷却时间的影响，结果表明，存在热阻时，冷却时间显著增加，随着塑件厚度的增加，热阻的影响逐渐减小。     

Investigation on the transferability of algorithms for the numerical optimization of cooling channel design in injection molding on metal gravity die casting

The thermal mold design and the identification of a proper cooling channel design are primordial steps in the development of complex molds for injection molding. In order to find a suitable cooling channel system, a lot of effort is needed to avoid part warpage after solidification. In current research, a simulative procedure to optimize the cooling channel layout iteratively is being developed at the Institute of Plastics Processing. These algorithms are transferred to the metal gravity die casting process, which has several similar requirements to the mold. Effectively, the simulation is simplified to a heat conduction problem. Instead of water, high temperature resistant oil is deployed and the casted material is a A356 aluminum alloy instead of semi‐crystalline plastics. The algorithm is adapted to these changed boundary conditions and the calculation of the optimized heat distribution is performed. Aim of this procedure is the construction of a mold producing parts with less warpage than a conventional mold.     

Analysis of thermal cycling efficiency and optimal design of heating/cooling systems for rapid heat cycle injection molding process

Rapid heat cycle molding (RHCM) is a molding process that the mold cavity is rapidly heated to a high temperature before plastic melt injection, and then cooled quickly once the cavity is completely filled. Heating/cooling efficiency and temperature uniformity of the RHCM system are two key technical parameters to ensure a high productivity and high-quality products. In this study, a numerical model to analyze the heat transfer in heating and cooling phases of RHCM was built. The effect of heating/cooling medium, layout and structure of the heating/cooling channels, mold structure, etc., on heating/cooling efficiency and temperature uniformity was studied and discussed by analyzing the thermal responses of the molding system in RHCM process. Based on the simulation results, the optimization design of the RHCM mold with hot-fluid heating was performed. Then, a new RHCM mold structure with a floating mold cavity was proposed to improve the heating/cooling efficiency and temperature uniformity. The effectiveness of this new mold structure was also verified by numerical experiments. At last, a RHCM production line with steam heating and water cooling was constructed for a thin-wall plastic part. In testing production, the molding systems can be heated and cooled rapidly with a molding cycle time of about 72 s. The production results show that the aesthetics of the molded parts was greatly enhanced and the weld mark on the plastic part’s surface was completely eliminated.     

中央空调循环冷却水系统节能技术

循环冷却水系统,主要的设备有冷水机组、冷却水泵、冷却塔,冷却介质是水。循环冷却水系统冷却水水质对该系统的影响很大;同时设备的选择和节能有很大的关系。分别从冷却水水质、冷水机组、冷却水泵、冷却塔等几个方面进行节能研究探讨。     

SCM435钢大方坯凝固过程组织的模拟

为了模拟不同冷却状态下的连铸坯的凝固组织,利用反算确定了SCM435钢325 mm×280 mm连铸坯的换热系数,采用有限元法模拟了连铸传热过程,获得了连铸坯的温度场及冷却速率,在此基础上与元胞自动机耦合模拟了连铸坯的凝固组织.研究发现,表面细晶区很大,且在连铸结晶器中完成形核并长大形成,而柱状晶开始形核于结晶器末端.降低形核数,晶粒密度、最大晶粒面积、平均半径存在不同程度的改变,其中晶粒的最大截面积增加了2.7倍,而微调成分对晶粒密度与平均半径影响较小,但同样凝固条件下晶粒不均匀程度有所加剧.     

Research of thermal response simulation and mold structure optimization for rapid heat cycle molding processes, respectively, with steam heating and electric heating

The dynamic mold temperature control system is the key of rapid heat cycle molding (RHCM) technology because it significantly affects the stability of the process, productivity and the quality of the final polymer part. For this reason, the approaches and techniques for dynamic mold temperature control were discussed in this study and two different dynamic mold temperature control methods, respectively, with steam heating and electric heating were found to be very feasible in mass production. The methods and principles of mold design for the two RHCM technologies were also discussed and then several different kinds of mold structures were designed. By constructing the corresponding thermal response analytical models for these RHCM molds, the temperature responses of the molding systems in the heating and cooling process of RHCM were simulated and studied. The effects of the mold design parameters such as the insulation layer between mold plate and mold inert, and mold material, on thermal response efficiency and temperature uniformity of the two RHCM processes were analyzed based on the simulation results. The results show that the insulation layer can increase the upper limit temperature of RHCM with steam heating and improve the heating speed of RHCM with electric heating. It can also greatly decrease the energy consumption of the two RHCM processes. The heating efficiency of RHCM with steam heating can be effectively improved by increasing the thermal conductivity of the cavity/core material, while the situation is diametrically opposite for RHCM with electric heating. Therefore, we acquired an optimized mold design principle and method for RHCM with steam heating and electric heating, respectively. Finally, a new electric heating mold with a cooling plate was proposed to enhance the cooling efficiency. The thermal response of this new electric heating mold was also simulated. The simulation results show that the cooling plate can significantly improve the cooling and heating efficiency.