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外文翻譯： Adaptive system for electrically driven thermoregulation of moulds for injection moulding 1. Introduction, definition of problem Development of technology of cooling moulds via thermoelectrical (TEM) means derives out of the industrial praxis and problems, i.e. at design, tool making and exploitation of tools.Current cooling technologies have technological limitations.Their limitations can be located and predicted in advance with finite element analyses (FEA) simulation packages but not completely avoided. Results of a diverse state of the art analyses revealed that all existing cooling systems do not provide controllable heat transfer capabilities adequate to fit into demanding technological windows of current polymer processing technologies. Polymer processing is nowadays limited (in term of shortening the production cycle time and within that reducing costs) only with heat capacity manipulation capabilities. Other production optimization capabilities are already driven to mechanical and polymer processing limitations. 1.1. Thermal processes in injection moulding plastic processing Plastic processing is based on heat transfer between plastic material and mould cavity. Within calculation of heat transfer one should consider two major facts: first is all used energy which is based on first law of thermodynamics—law of energy conservation , second is velocity of heat transfer. Basic task at heat transfer analyses is temperature calculation over time and its distribution inside studied system. That last depends on velocity of heat transfer between the system and surroundings and velocity of heat transfer inside the system. Heat transfer can be based as heat conduction, convection and radiation . 1.2. Cooling time Complete injection moulding process cycle comprises of mould closing phase, injection of melt into cavity, packing pressure phase for compensating shrinkage effect, cooling phase, mould opening phase and part ejection phase. In most cases, the longest time of all phases described above is cooling time. Cooling time in injection moulding process is defined as time needed to cool down the plastic part down to ejection temperature. The main aim of a cooling process is to lower additional cooling time which is theoretically needless; in praxis, it extends from 45 up to 67% of the whole cycle time. From literature and experiments, it can be seen, that the mould temperature has enormous influence on the ejection time and therefore the cooling time (costs). Injection moulding process is a cyclic process where mould temperature varies as shown in Fig. 1 where temperature varies from average value through whole cycle time. 2. Cooling technology for plastic injection moulds As it was already described, there are already several different technologies, enabling the users to cool the moulds. The most conventional is the method with the drilling technology, i.e. producing holes in the mould. Through these holes (cooling lines), the cooling media is flowing, removing the generated and accumulated heat from the mould. It is also very convenient to build in different materials, with different thermal conductivity with the aim to enhance control over temperature conditions in the mould. Such approaches are so called passive approaches towards the mould temperature control. The challenging task is to make an active system, which can alter the thermal conditions, regarding to the desired aspects, like product quality or cycles time. One of such approaches is integrating thermal electrical modules (TEM), which can alter the thermal conditions in the mould, regarding the desired properties. With such approach, the one can control the heat transfer with the time and space variable, what means, that the temperature can be regulated throughout the injection moulding cycle, independent of the position in the mould. The heat control is done by the control unit, where the input variables are received from the manual input or the input from the injection moulding simulation.With the output values, the control unit monitors the TEM module behaviour. 2.1. Thermoelectric modules (TEM) For the needs of the thermal manipulation, the TEM module was integrated into mould. Interaction between the heat and electrical variables for heat exchange is based on the Peltier effect. The phenomenon of Peltier effect is well known, but it was until now never used in the injection moulding applications. TEM module (see Fig. 2) is a device composed of properly arranged pairs of P and N type semiconductors that are positioned between two ceramic plates forming the hot and the cold thermoelectric cooler sites. Power of a heat transfer can be easily controlled through the magnitude and the polarity of the supplied electric current. 2.2. Application for mould cooling The main idea of the application is inserting TEM module into walls of the mould cavity serving as a primary heat transfer unit. Such basic assembly can be seen in Fig. 3. Secondary heat transfer is realized via conventional fluid cooling system that allows heat flows in and out from mould cavity thermodynamic system. Device presented in Fig. 3 comprises of thermoelectric modules (A) that enable primarily heat transfer from or to temperature controllable surface of mould cavity (B). Secondary heat transfer is enabled via cooling channels (C) that deliver constant temperature conditions inside the mould. Thermoelectric modules (A) operate as heat pump and as such manipulate with heat derived to or from the mould by fluid cooling system (C). System for secondary heat manipulation with cooling channels work as heat exchanger. To reduce heat capacity of controllable area thermal insulation (D) is installed between the mould cavity (F) and the mould structure plates (E). Fig. 3. The whole application consists of TEM modules, a temperature sensor and an electronic unit that controls the complete system. The system is described in Fig. 4 and comprises of an input unit (input interface) and a supply unit (unit for electronic and power electronic supply—H bridge unit). The input and supply units with the temperature sensor loop information are attached to a control unit that acts as an execution unit trying to impose predefined temperate/time/position relations. Using the Peltier effect, the unit can be used for heating or cooling purposes. The secondary heat removal is realized via fluid cooling media seen as heat exchanger in Fig. 4. That unit is based on current cooling technologies and serves as a sink or a source of a heat. This enables complete control of processes in terms of temperature, time and position through the whole cycle. Furthermore, it allows various temperature/time/position profiles within the cycle also for starting and ending procedures. Described technology can be used for various industrial and research purposes where precise temperature/time/position control is required. The presented systems in Figs. 3 and 4 were analysed from the theoretical, as well as the practical point of view. The theoretical aspect was analysed by the FEM simulations, while the practical one by the development and the implementation of the prototype into real application testing. 3. FEM analysis of mould cooling Current development of designing moulds for injection moulding comprises of several phases . Among them is also design and optimization of a cooling system. This is nowadays performed by simulations using customized FEM packages (Moldflow ) that can predict cooling system capabilities and especially its influence on plastic.With such simulations, mould designers gather information on product rheology and deformation due to shrinkage as ell as production time cycle information. This thermal information is usually accurate but can still be unreliable in cases of insufficient rheological material information. For the high quality input for the thermal regulation of TEM, it is needed to get a picture about the temperature distribution during the cycle time and throughout the mould surface and throughout the mould thickness. Therefore, different process simulations are needed. 3.1. Physical model, FEM analysis Implementation of FEM analyses into development project was done due to authors’ long experiences with such packages and possibility to perform different test in the virtual environment. Whole prototype cooling system was designed in FEM environment (see Fig. 5) through which temperature distribution in each part of prototype cooling system and contacts between them were explored. For simulating physical properties inside a developed prototype, a simulation model was constructed using COMSOL Multiphysics software. Result was a FEM model identical to real prototype (see Fig. 7) through which it was possible to compare and evaluate results. FEM model was explored in term of heat transfer physics taking into account two heat sources: a water exchanger with fluid physics and a thermoelectric module with heat transfer physics (only conduction and convectionwas analysed, radiation was ignored due to low relative temperature and therefore low impact on temperature). Boundary conditions for FEM analyses were set with the goal to achieve identical working conditions as in real testing. Surrounding air and the water exchanger were set at stable temperature of 20 ?C. Fig. 6. Temperature distribution according to FEM analysis. Fig. 7. Prototype in real environment. Results of the FEM analysis can be seen in Fig. 6, i.e. Temperature distributi through the simulation area shown in Fig. 5. Fig. 6 represents steady state analysis which was very accurate in comparison to prototype tests. In order to simulate the time response also the transient simulation was performed, showing very positive results for future work. It was possible to achieve a temperature difference of 200 ?C in a short period of time (5 s), what could cause several problems in the TEM structure. Those problems were solved by several solutions, such as adequate mounting, choosing appropriate TEM material and applying intelligent electronic regulation. 3.2. Laboratory testing As it was already described, the prototype was produced and tested (see Fig. 7). The results are showing, that the set assumptions were confirmed. With the TEM module it is possible to control the temperature distribution on different parts of the mould throughout the cycle time. With the laboratory tests, it was proven, that the heat manipulation can be practically regulated with TEM modules. The test were made in the laboratory, simulating the real industrial environment, with the injection moulding machine Krauss Maffei KM 60 C, temperature sensors, infrared cameras and the prototype TEM modules. The temperature response in 1.8 s varied form +5 up to 80 ?C, what represents a wide area for the heat control within the injection moulding cycle. 4. Conclusions Use of thermoelectric module with its straightforward connection between the input and output relations represents a milestone in cooling applications. Its introduction into moulds for injection moulding with its problematic cooling construction and problematic processing of precise and high quality plastic parts represents high expectations. The authors were assuming that the use of the Peltier effect can be used for the temperature control in moulds for injection moulding.With the approach based on the simulation work and the real production of laboratory equipment proved, the assumptions were confirmed. Simulation results showed a wide area of possible application of TEM module in the injection moulding process. With mentioned functionality of a temperature profile across cycle time, injection moulding process can be fully controlled. Industrial problems, such as uniform cooling of problematic A class surfaces and its consequence of plastic part appearance can be solved. Problems of filling thin long walls can be solved with overheating some surfaces at injection time. Furthermore, with such application control over rheological properties of plastic materials can be gained. With the proper thermal regulation of TEM it was possible even to control the melt flow in the mould, during the filling stage of the mould cavity. This is done with the appropriate temperature distribution of the mould (higher temperature on the thin walled parts of the product). With the application of TEM module, it is possible to significantly reduce the cycle time in the injection moulding process. The limits of possible time reduction lies in the frame of 10–25% of additional cooling time, describe in Section 1.2 .With the application of TEM module it is possible to actively control the warping of the product and to regulate the amount of product warpage in the way to achieve required product tolerances. The presented TEM module cooling application for injection moulding process is a matter of priority note for the patent, held and owned by TECOS. 注塑模具之電力驅動溫度調(diào)節(jié)系統(tǒng) ------材料加工技術雜志187–188 (2007) 690–693 1、 文章的定義和介紹 通過熱電（TEM）手段冷卻模具技術的發(fā)展，派生出的工業(yè)實踐和問題，即在設計，制作工具和開發(fā)工具之中形成。當前的冷卻技術有技術上的限制，通過有限元分析模擬包的提前預測可以發(fā)現(xiàn)這些局限，但是不能夠完全避免。各種不同的分析結果顯示，現(xiàn)在所有的冷卻系統(tǒng)不能夠提供可控制的傳熱能力，而足以適應目前聚合物加工工藝要求的技術窗口。 當前聚合物的加工是在熱容量處理能力上被限制的（從生產(chǎn)周期和降低成本上看）。其他生產(chǎn)優(yōu)化功能幾經(jīng)突破了機械和聚合物加工的限制。 1.1.注射成型塑料加工中的熱處理工藝 塑料加工是以塑件材料和模具型腔之間的熱量轉移為基礎的，在熱傳遞的計算中應該考慮兩個主要事實：第一是所有使用的能源應該遵循能量守恒的熱力學第一定律，第二個是傳熱速度。熱傳遞分析的基本任務是隨著時間的推移和在被研究系統(tǒng)內(nèi)部的溫度分布計算。最后取決于系統(tǒng)和環(huán)境之間、系統(tǒng)內(nèi)部之間的熱量傳遞速率。塑料加工產(chǎn)生的熱量可以通過熱傳導、對流和輻射進行傳遞。 1.2.冷卻時間 完整的注塑成型工藝周期包括合模階段，熔體注入型腔階段，保持壓力補償收縮效果階段，冷卻階段，開模階段和部分彈射階段。在大多數(shù)情況下，以上所描述的所有階段中，所需時間最長的是冷卻階段。 在注塑過程中，冷卻時間定義為塑料部件的溫度降到可以被彈射出時而所需要的時間。 冷卻過程的主要目的是為了降低額外的冷卻時間，但這在理論上是沒有必要的，在實際生產(chǎn)中，冷卻時間會在整個生產(chǎn)周期中由45%增加到67%。 從大量的文獻和實驗中可知，模具自身的溫度對于模具的排出時間，尤其是冷卻時間有巨大的影響。 模具注塑成型過程是一個循環(huán)的過程中，模具溫度變化如圖1所示，由圖可看出模具溫度的變化跨過整個生產(chǎn)周期的平均值。 二、注塑模具的冷卻技術 由于作了一些說明，現(xiàn)在已經(jīng)有幾個不同的冷卻技術，這樣可以幫助廠家冷卻模具。最常用的冷卻方法就是鉆孔技術，即在模具上鉆出一些空。通過這些小孔（冷線），流動的冷卻介質可以從模具中帶走注塑時產(chǎn)生和積累的熱量。這些小孔同樣可以很方便的鉆在不同的材料上，為了增強對模具溫度的控制，應使用不同于模具材料熱傳導率的冷卻介質。因此這種調(diào)控溫度的方法對于模具的溫度控制來說是被動的。 做出一個主動調(diào)節(jié)溫度的系統(tǒng)，即可以改變熱量狀況，從而得到期望的方面，例如產(chǎn)品質量或周期時間，而這是一個具有挑戰(zhàn)性的任務。這種做法之一就是整合熱電氣模塊(TEM),他可以改變模具熱量條件，從而得到理想的模具特性。用這種方法，可以在時間變量和空間變量下控制熱量傳遞，這就意味著，模具溫度可以通過注塑周期來被調(diào)節(jié)，而不受模具自身各部位的影響。熱量控制可以通過控制單元完成，控制單元中的輸入變量可由人工輸入或注塑模擬輸入而被接收。在有輸出值的情況下，控制單元可以監(jiān)視TEM模塊的運行狀況。 2.1.熱電模塊（TEM) 因為熱量控制的需要，熱電模塊被集成到模具之中。熱變量和電氣變量之間的相互作用來改變熱量是基于珀耳帖效應，珀耳帖效應的現(xiàn)象眾周所知的，但它到現(xiàn)在為止從未在注塑應用中使用過。TEM模塊是一種位于兩個陶瓷板之間的合理布置的幾套P型和N型半導體構成的裝置，從而形成冷的和熱的電勢點。熱量傳遞的功率易于被提供電流的大小和極性來控制。 2.2.模具冷卻的應用 該應用的主要目的是將TEM模塊插入模具型腔的內(nèi)壁中來作為一個主要的熱量傳遞裝置。 由圖3可以看出熱電模塊的基本裝配，通過常規(guī)的液體冷卻系統(tǒng)，使熱流量通過模腔熱力系統(tǒng)以實現(xiàn)二次換熱。 在圖3中，該裝置由熱電模塊（A)組成，它可以將大部分熱量傳遞到溫度可以被控制的模具型腔的表面上(B)。經(jīng)過冷卻通道（C)以實現(xiàn)二次傳熱，這樣可以使模具內(nèi)部溫度保持不變。熱電模塊(A)作為熱力泵來運轉，這樣可以通過流體冷卻系統(tǒng)(C)來控制熱量在模具內(nèi)導入或導出。整個系統(tǒng)是在冷卻通道下進行二次熱量控制的熱轉換工作。為了減少熱容量可控區(qū)域，絕緣體(D)被安裝在模腔(F)和模具結構板(E)之間。 整個應用包括溫度模塊，溫度傳感器和一個控制整個系統(tǒng)的電子裝置。這個系統(tǒng)描述如圖4所示，其中包括輸入單元（輸入接口）和應用單元（電子單元和電力電子供應，即H橋單元）。 溫度傳感器的循環(huán)信息的輸入和供應單元都連接到一個控制單元 ，其作為一種執(zhí)行元件試圖加強預先確定的溫度/時間/位置關系。應用珀爾帖效應 ，這個執(zhí)行元件可以用于加熱或冷卻。 通過流體冷卻介質，二次熱量的消除可以實現(xiàn)，由圖4的熱量轉換可以看出。該執(zhí)行單元是基于目前的冷卻技術，并作為一個散熱器或熱源來使用。這使得在溫度，時間和位置方面的整個循環(huán)過程中實現(xiàn)完全控制成為可能。此外，它允許在循環(huán)過程中不同溫度/時間/位置結構可以開始和停止進程。以上所敘述的工藝可以用于那些要求精確控制溫度/時間/位置的不同產(chǎn)業(yè)和科研之中。圖3和圖4所展現(xiàn)的系統(tǒng)是從理論和實際的關點來分析的。理論方面是通過有限元模擬分析的，而實踐方面是將元件通過真實環(huán)境應用程序測試來實現(xiàn)并發(fā)展起來的。 三、模具冷卻的有限元分析 目前注塑模具設計的發(fā)展，包括幾個階段。其中也包括冷卻系統(tǒng)的設計和優(yōu)化階段。這是目前通過模擬來執(zhí)行并使用定制的有限元建模包，它可以預測冷卻系統(tǒng)的功能，尤其是它對塑料制品的影響力。依據(jù)這種模擬，模具設計人員可以收集到產(chǎn)品流變、產(chǎn)品收縮變形和產(chǎn)品生產(chǎn)周期的綜合信息。 這種熱量信息通常是準確的，但是由于材料流變信息的不足，它仍然是不可信的。為了對熱電模塊調(diào)節(jié)系統(tǒng)有高質量的輸入，在整個注塑循環(huán)周期中，需要一個溫度分布圖，并貫穿模具表面和模具厚度層。因此需要不同工藝模擬。 3.1.物理模型，有限元分析 由于工作人員大量經(jīng)驗而積累如此多的數(shù)據(jù)和在虛擬環(huán)境中成功完成不同實驗可能性上，而使有限元分析法能在已發(fā)展項目上成功實施。整個冷卻系統(tǒng)原型是在有限元環(huán)境中設計的，且貫穿冷卻系統(tǒng)原型的每一部分溫度分布，同時對這些聯(lián)系進行了探討。為了模擬已開發(fā)原型的內(nèi)在物理特性，可以使用COMSOL Multiphysics軟件構建一個仿真模型。結果有限元模型和實際模型是一樣的，并且通過它有了比較和評估的可能性。 從熱量轉換的物理現(xiàn)象觀點探討有限元模型時，應該考慮兩個熱源：一個是 水變換和流體物理，一個是熱電模塊與熱物理轉換（僅僅分析了傳導和對流，由于相對溫度低，輻射影響被忽視了，所以對溫度影響也低）。 在實際試驗中，有限元分析的邊界條件被設定為獲得同樣工作條件的這樣一個目標。周圍的空氣轉換器和水轉換器設定為20?C穩(wěn)定的溫度。 Fig. 6. Temperature distribution according to FEM analysis. Fig. 7. Prototype in real environment. 在圖6中可以觀察到有限元分析的結果，圖5顯示了模擬區(qū)域的溫度分布情況，圖6描述了在穩(wěn)定狀態(tài)下的分析情況，和樣機試驗相比，這是非常準確的。為了模擬響應時間，同時也進行了瞬時模擬，這對于以后的工作顯示出了非常積極的效果。這在很短的時間內(nèi)可能會達到200 ?C，以至于熱電模塊結構會產(chǎn)生一些難題。這些問題已經(jīng)被幾個解決方案解決了，比如適當?shù)陌惭b，選擇合適的TEM材料和智能電子調(diào)節(jié)的應用。 3.2.實驗室測試 因為已近描述過，這樣的型號也已經(jīng)制作出來并作了測試（如圖7所示）。由顯示的結果可知，先前設定的假設也被證實了。在注塑周期的時間內(nèi)，TEM模塊控制模具不同部位的溫度分布是可能的。由實驗室的測試證明，TEM模塊確實可以控制熱處理的問題。在有注塑機Krauss Maffei KM 60 C，溫度傳感器，紅外線照相機和原型TEM模塊的情況下，這個實驗，即模擬真實工業(yè)環(huán)境，在實驗室中完成了。實驗的溫度在1.8秒內(nèi)由5攝氏度到80攝氏度變化著，這代表了在注塑周期內(nèi)有一個大的溫度控制區(qū)域。 四、結論 在輸入和輸出的關系中，使用熱電模塊有著直接的聯(lián)系，這在冷卻技術的應用中是有里程碑的意義。注塑模具時，把熱電模塊引入不穩(wěn)定的冷卻結構中，不準確的工藝精度中和高質量的塑料結構中這一技術顯示出了很高的期望。 作者假設在注塑模具時運用珀爾帖效應可以實現(xiàn)溫度控制。隨著模擬工作的開始和實驗室設備的實際生產(chǎn)，這些假設被證實了。模擬的結果表明在注塑過程中TEM模塊可能會有很大的應用空間。 隨著在周期時間里溫度曲線功能的提及，注塑過程可以被完全控制。現(xiàn)在可以解決的工業(yè)問題，例如均勻冷卻的有問題的一類表面和塑料部分外觀的形狀等。在注塑時間里提高一些表面的溫度，這樣可以解決注塑薄壁塑件的難題。此外，利用這些技術，控制塑性材料的流變特性就可以實現(xiàn)了。在填充模腔階段，合理調(diào)節(jié)熱電模塊的熱量，它就可能甚至可以調(diào)控模腔里的熔融液體，這樣做是運用了模具中合適的問題分布（產(chǎn)品中的薄壁部分應有更高的溫度）。 在注塑過程中，應用TEM模塊技術減少周期時間的可能性是非常明顯的，可能減少周期時間的限制在于會有10—25%的額外冷卻時間，這在1.2節(jié)中描述過。 隨著TEM模塊技術的應用，它可以很好地控制產(chǎn)品的扭曲和產(chǎn)品扭曲的數(shù)量，以這種方法就可以獲得要求的產(chǎn)品尺寸。 因為TECOS擁有TEM模塊冷卻的技術，所以在注塑工藝時應優(yōu)先考慮這種技術的專利問題。 13