瓶蓋注塑模具設計
瓶蓋注塑模具設計,瓶蓋,注塑,模具設計
附錄2
Fundamentals of Mechanical Design
As a plastic polymer chemistry and materials science and the development of the important achievements already familiar, Plastic products have become productive human life and an indispensable important component. Over the years, the plastic products industry has been developing rapidly, As the global scope of plastic instead of metal trend has been further accelerated the pace of development. Plastic products are generally used molding methods of production, thereby plastic mold has become an important production technology and equipment, in the national economy plays an increasingly important role. With plastic products in the home appliances, electronic products and other daily necessities to the increasingly widespread application on the plastic mold design and manufacturing requirements are also increasing. Traditional manual design and manufacturing has long since failed to meet production needs. CAD and CAM development is adapted to the actual requirements of this objective. CAD/CAM be significantly enhanced plastic products, and plastic mold design and manufacturing efficiency and raise the quality of design and manufacture. reduce tryout repair mode, thus shortening from plastic product design, mold design, Mold manufacture of molded products for the entire production cycle.
1，plastic mold CAD
CAD design and computer organic combination play their respective expertise to the new design methods. That the design staff in the design process, giving full play to a powerful computer computing, information storage and the ability to rapidly identify, complete information management, numerical calculation, simulation analysis, Optimum design and drafting tasks designers concentrate on effective creative thinking, in order to better accomplish the program from the design, evaluation, simulation and analysis of specific modifications to the design of the whole process.
CAD development generally follows : electronic drawing board system (2-D computer graphics technology), surface modeling system, solid modeling, parametric technology and variable technology. Electronic drawing board system is the traditional view of the three ways to express parts of the media to the drawings for technical exchange. Surface modeling system is developed in the two-dimensional mapping system, which is based on Bessel algorithm, introduction of 3D surface modeling system, it is the first CAD revolution. Solid modeling technology can convey accurately the quality of parts and the center, away from inertia characteristics, It marks the universal application of CAD history of the development of the second revolution and the future development direction of the CAD. Parametric Technology is an unconstrained free than to create more innovative and better algorithm, which is characterized by : Based on the characteristics, full size constraints, all relevant data, dimension driven design changes. Parametric Technology Application dominated the history of the development of graphics third revolution. As the "full size constraint" mandatory interference and constrains the designer's creativity and imagination in the design of the key physical topology change, the loss of certain binding characteristics data, it will cause confusion, result in a Parametric Technology modeled on the more advanced solid modeling - variable technique.
2, plastic mold CAE
CAE (Computer Aided Execution) (31 computer-aided engineering technology that It is the emergence of computer-aided design / computer-aided manufacturing (CAD/CAM) technology to the development of the depth direction requirements. M general it is a numerical calculation includes technical, databases, computer graphics , engineering analysis and simulation of an integrated software system Its core technology is the engineering model and numerical method. Mold on the computer-aided engineering technique , it is primarily the use of polymer rheology, heat transfer, numerical methods and computer graphics, and other basic theory the plastic molding process simulation of the mold before it can create the image , directly on the computer screen simulate the actual process of forming forecast mold design and molding conditions on the impact of products found potential defects for the judgment of mold design and molding conditions provide reasonable scientific basis. With computer technology is developing rapidly , the various plastic molding process simulation of plastic processing industry has become a hot spot. Now tell us about CAE technology in Note molding and gas-assisted injection molding applications.
(1) Injection Molding
CAE in the injection mold, the mold filling for mobile, packing, cooling and warpage analyzed.
Filling flow analysis can be made the following major tasks : optimization of casting system included in the balanced flow on the basis of rational flow channel size, distribution and the best runner number, location and shape; Optimal injection parameters, the analysis of flow front; Weld line gas analysis Point location; pressure field, temperature and velocity analysis
Packing refers to the process in order to be satisfied with the products, Filling in the end still higher packing under pressure to the cavity to the feed to compensate for the temperature, pressure changes caused by volumetric shrinkage. Pressure is the essence of the process feed mainly used to predict melt in the cavity fill material and compaction process pressure, temperature, calculate volumetric shrinkage cavity and the shear stress and changes in the density.
Cooling process melting plastics occurred curing, curing process by giving off heat from the coolant die away. The process of mold cavity temperature and the uniformity of a direct impact on the production of injection molded parts efficiency and quality. Chang main design parameters including : cooling pipe size, and the location of the cold tp pipeline linking relations geometric parameters and the coolant flow, inlet temperature and other physical parameters. A good cooling system should make Die achieve rapid and balanced cooling to reduce the cooling time, increase the productivity and and reduce or avoid warpage plastic parts, residual stress and surface quality defects, improving the quality of products. Warpage analysis is the application of the basic principles of mechanics and FEM / IsW difference numerical algorithm, Calculation of plastic parts molding size and deformation
(2) gas-assisted injection molding
Gas-assisted injection molding in the traditional injection molding developed on the basis of a new injection molding process. Its features is : filling stage to the cavity injection high-pressure gas; In the packing stage, and continue to inject high-pressure gas melt to compensate for the cooling caused by the contraction.
Because gas, melt two entirely different dynamic interaction of material, makes molding process simulation is very complicated. The governing equations of non-Newtonian fluid under non-isothermal the Hele-Shaw flow, but assumed the gas cladding interface that the gas, melt two-phase media is not mixed. Thus, the flow field for the melt flow into the equation solving, Melting only in the gas interface of gas pressure at the top of the boundary conditions. Particle tracking normally used to control gas or gas fusion method to determine the interface.
Gas Aided Design Process of CAE technology can resolve the following issues : gas. Cavitation potential -- through the quality issues; Melt determine the optimal size of the gas injected into the best time of process parameters; obtain more cavity system in the whole processing of materials and gas distribution; Optimization flow, the gating system size, Layout programs.
3, CAE software brief
MF software is a specialized in plastic computer aided engineering analysis (CAE) software and consulting firms (MOL DFLO~) development. MOLDFLO~ software can simulate the entire injection process and the process of injection molding products affected. They mainly consist of flow simulation module (MF~Flow), cooling simulation module (MF/Cool) Pressure Analysis Module (MFIPack), warping analysis module (MFl9Crrap) MF/SHRINK mold cavity to determine the size, structure MF/STRESS stress analysis MF/O~M injection molding machine parameter optimization, MF/GAS gas-assisted injection analysis, MF/FIBER plastic parts fiber orientation analysis module, simulation and analysis to determine the reasonable die structure and the technical parameters of appropriateness. The latest version can automatically establish and run a series of analysis, after the analysis of the structure will be automatically generated.
4, CAD and CAE design of the general steps Die
Plastic mold cavity and the core is plastic parts geometry of the design, therefore, first step in the design of plastic parts to describe the shape of three plastic parts of the computer model accurately established, Mold it into the entire design process and the basis for the foundation. Then proceed to the preliminary program of mold design, mold design of gating system and cooling systems. CAE software mode analysis, thereby optimizing the structure of mold design, based on an analysis of the results of pouring, Cooling system amendment. Plastic Parts will join three-dimensional model than can be contracted mold parts 3D model. Will tie in with the mold parts (such as Insert, pumping cores) 3D assembly model for interference checking. On the assembly projection models, such as cutting operation can be mold assembly map Molding of the same components for the operation is likely to be the two-dimensional engineering drawings. Mold parts of the 3D model can be used to generate CAM NC machining process.
5, the end of Language
Currently, plastic mold design, generic manufacturers generally use the machinery CAD/CAM software and specialized CAE software combination. Development and promotion of specialized CAD software is the issue. CAE analysis only under the conditions set for plastic molding process simulation, it is not the result of analysis, the optimum nor can the design process for the guidance of experts. Integrated special plastic mold CAD and CAE software, enhancing its intelligence, CAD and CAE is a plastic mold technology development trends.
譯文如下：
CAD/CAE在塑料模具設計中的應用
前言
塑料作為高分子化學和材料科學發(fā)展的重要成果，早已為人們熟悉，塑料產(chǎn)品已經(jīng)成為人類生產(chǎn)和生活中不可缺少的重要組成部分。多年來，塑料產(chǎn)品制造業(yè)一直在迅速發(fā)展，而當前全球范圍的以塑料代替金屬的趨勢又進一步加速了這一發(fā)展速度。塑料產(chǎn)品一般采用模塑成型方法生產(chǎn)，因而塑料模具早已成為一種重要的生產(chǎn)工藝裝備，在國民經(jīng)濟中起著越來越重要的作用。隨著塑料產(chǎn)品在家電、電子等產(chǎn)品和日常用品中的越來越廣泛應用，對塑料模具的設計和制造的要求也越來越高。傳統(tǒng)的手工設計與制造方式早已滿足不了生產(chǎn)發(fā)展的需要。CAD/CAM的發(fā)展正適應了這種客觀實際要求。CAD/CAM可以顯著提高塑料產(chǎn)品和塑料模具的設計制造效率，提高設計制造質量，減少試模修模時間，從而縮短從塑料產(chǎn)品設計、模具設計、模具制造到進行產(chǎn)品模塑生產(chǎn)的整個周期。
一、塑料模具CAD
CAD是設計人員和計算機的有機結合、發(fā)揮各自特長的新型設計方法。即設計人員在設計過程中，充分發(fā)揮計算機的強大運算功能、信息存儲與快速查找的能力，完成信息管理、數(shù)值計算、分析模擬、優(yōu)化設計和繪圖等任務而設計人員集中精力進行有效的創(chuàng)造性思維，從而更好地完成從設計方案的提出、評價、分析模擬與修改到具體設計實施的全過程。
CAD的發(fā)展大致經(jīng)過：電子圖板系統(tǒng)(二維計算機繪圖技術)、曲面造型系統(tǒng)、實體造型技術、參數(shù)化技術和變量化技術。電子圖板系統(tǒng)是用傳統(tǒng)的三視圖方法來表達零件，以圖紙為媒介進行技術交流。曲面造型系統(tǒng)是開發(fā)者在二維繪圖系統(tǒng)的基礎上，采用貝賽爾算法，推出三維曲面造型系統(tǒng)，它是CAD的第一次革命。實體造型技術可準確表達零件的質量、重心、慣性距等特征，它的普及應用標志著CAD的發(fā)展史上的第二次革命，代表著未來CAD的發(fā)展方向。參數(shù)化技術是一種比無約束自由制造更新穎更好的算法，它的特點是：基于特征、全尺寸約束、全數(shù)據(jù)相關、尺寸驅動設計修改。參數(shù)化技術的應用主導了cAD發(fā)展史上的第三次革命。由于“全尺寸約束″這一硬性規(guī)定干擾和制約了設計者的創(chuàng)造力及想象力，在設計中關鍵形體的拓撲關系發(fā)生改變，失去了某些約束的特征就會造成系統(tǒng)數(shù)據(jù)混亂，因而提出了以參數(shù)化技術為藍本的更先進的實體造型—變量化技術。
二、塑料模具CAE
CAE ( Computer Aided Execution)(31即計算機輔助工程技術，它的出現(xiàn)是計算機輔助設計/計算機輔助制造(CAD/CAM )技術向縱深方向發(fā)展的要求。一般M為它是一個包含數(shù)值計算技術、數(shù)據(jù)庫、計算機圖形學、工程分析與仿真等在內的一個綜合性軟件系統(tǒng)，其核心技術是工程問題的模型化和數(shù)值實現(xiàn)方法。就塑料模具計算機輔助工程技術而言，它主要是利用高分子流變學、傳熱學、數(shù)值計算方法和計算機圖形學等基本理論，對塑料成型過程進行數(shù)值模擬，在模具制造之前就可以形象、直觀地在計算機屏幕上模擬實際成型過程，預測模具設計和成型條件對產(chǎn)品的影響，發(fā)現(xiàn)可能出現(xiàn)的缺陷，為判斷模具設計和成型條件是否合理提供科學的依據(jù)。隨著計算機技術的快速發(fā)展，對各種塑料 成型過程的模擬成為塑料加工業(yè)研究的熱點。下面介紹一下CAE技術在注射成型和氣體輔助注射成型中的應用。
（一）注射成型
在注射模CAE中，可作充模流動、保壓、冷卻及翹曲變形等分析。
充模流動分析主要可以作以下工作:優(yōu)化澆注系統(tǒng)，包括在平衡流動的基礎上確定合理的流道尺寸、分布及最佳的澆口數(shù)量、位置和形狀;優(yōu)化注射工藝參數(shù)、流動前沿的分析;熔接線和氣穴位置的分析;壓力場、溫度場和速度場的分析。
保壓過程是指為了得到滿意的制品，在充模結束時仍需在較高的保壓壓力的作用下向型腔內繼續(xù)注料，以彌補由于溫度、壓力變化造成的體積收縮。保壓過程的實質是補料，主要用于預測熔體在型腔補料與壓實過程的壓力場、溫度場，計算體積收縮和型腔剪切應力及密度變化的情況。
冷卻過程中熔融塑料發(fā)生固化，固化過程中放出的熱量通過模具由冷卻介質帶走。該過程中模具型腔溫度的高低及均勻性直接影響到注塑件的生產(chǎn)效率和質量。萇主要設計參數(shù)包括:冷卻，管道的尺寸、位置及各冷tp管道的連接關系等幾何參數(shù)和冷卻介質的流量、進口溫度等物理參數(shù)。一個好的冷卻系統(tǒng)應該使模具達到快速、均衡的冷卻，以減少冷卻時間，提高成型效率，并減少或避免塑件翹曲變形、殘余應力及表面質量缺陷等，提高產(chǎn)品質量。翹曲變形分析是應用力學的基本原理及有限元/有IsW差分等數(shù)值算法，計算塑件的成型尺寸及變形量。
?。ǘ怏w輔助注射成型
氣體輔助注射成型是在傳統(tǒng)注射成型的基礎上發(fā)展起來的一種創(chuàng)新的注射成型工藝。其特點在于:在充填階段，向型腔內注入高壓氣體;在保壓階段，繼續(xù)注入高壓氣體，以彌補因 熔體冷卻而引起的收縮。
由于氣體、熔體這兩種性質完全不同的物質動力 學相互作用，使得成型過程的模擬非常復雜?？刂品匠獭〔捎梅桥ｎD流體非等溫下的Hele—Shaw流動，但假設在氣熔界面，認為氣體、熔體兩相介質不混合。這樣，流 場的求解變?yōu)閷θ垠w流動方程的求解，僅在氣熔界面上力口上氣體壓力的邊界條件。一般采用粒子跟蹤法或控制氣體法確定氣熔界面。
用氣體輔助設計成型過程的CAE技術，可以解 決下列問題:發(fā)現(xiàn)氣體、氣穴沖透等潛在的質量問題; 確定熔體的最優(yōu)體積、注人氣體的最佳切入時間等工藝參數(shù);獲得多型腔系統(tǒng)在整個加工過程中的物料及 氣體分布;優(yōu)化流道、澆注系統(tǒng)的尺寸、布置方案等。
三、 CAE軟件簡介
MF軟件是由一家專門從事塑料計算機輔助工程分析(CAE)的軟件和咨詢公司(MOLDFLO~)開發(fā)的。MOLDFLO~軟件可以模擬整個注射過程以及這一過 程對注射成型產(chǎn)品的影響。它主要包括流動模擬模塊(MF~Flow)、冷卻模擬模塊( MF/Cool )、保壓分析模塊(MFIPack )、翹曲分析模塊( MFl9Crrap )、MF/SHRINK模腔尺寸確定、MF/STRESS結構應力分析、MF/O~M注塑機參數(shù)優(yōu)化、MF/GAS氣體輔助注射分析、MF/FIBER塑件纖維取向分析等模塊，通過模擬與分析可以判斷模具結構的合理性和成型工藝參數(shù)的適宜性。最新版本可以自動建立和運行一系列的分析，分析結束后，分析結構將自動生成。
四、CAD/CAE設計模具的一般步驟
塑料模的型腔和型芯是根據(jù)塑件的幾何形狀設計的，因此，設計時第一步是對塑件的形狀進行描述，將塑件的三位模型在計算機中準確地建立起來，使它成為模具設計整個過程的基礎和依據(jù)。然后進行模具方案的初步設計，設計模具的澆注系統(tǒng)和冷卻系統(tǒng)，利用CAE軟件作模流分析，從而優(yōu)化模具結構設計，根據(jù)分析結果對澆注、冷卻系統(tǒng)進行修正。將塑件三維模型加入收縮比即可得到模具成型零件三維模型。將其與模具配合零件(如鑲塊、抽芯等)的三維模型裝配進行干涉檢查。對裝配模型進行投影、剖切等操作即可得到模具總裝圖，對模具成型零件進行相同的操作即可得到相應的二維工程圖。模具成型零件的三維模型可用于CAM以產(chǎn)生NC加工程序。
五、結束語
目前，塑料模具設計、制造一般采用通用機械的CAD/CAM軟件與專用塑料模CAE軟件相結合。開發(fā)與推廣專用模具CAD軟件是面臨的一個課題。CAE分析只能在設定條件下對塑料成型過程進行模擬，還不能對分析結果進行優(yōu)化，更不能對設計過程作專家指導。集成專用的塑料模具CAD/CAE軟件，提高其智能化程度，是塑料模CAD/CAE技術發(fā)展的趨勢。
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譯文原文出處：Eric Bryant 南京工業(yè)出版社 2006年
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