Concurrent Design of Plastics Injection Moulds
凸函数定义
Assist.Prof.Dr. A. YAYLA /Prof.Dr. Paş a YAYLA
Abstract
The plastic product manufacturing industry has been growing rapidly in recent years. One of the most popular process for making plastic parts is injection moulding. The design of injection mould is critically important to product quality and efficient product processing. Mould-making companies, who wish to maintain the competitive edge, desire to shorten both design and manufacturing leading times of the by applying a systematic mould design process.
The mould industry is an important support industry during the product development process, rving as an important link between the product designer and manufacturer. Product development has changed from the traditional rial process of design, followed by manufacture, to a more organized concurrent process where design and manufacture are considered at a very early stage of design. The concept of concurrent engineering (CE) is no longer new and yet it is still applicable and relevant in today’s manuf acturing environment. Team working spirit, management involvement, total design process and integration of IT tools are still the esnce of CE. The application of The CE process to the
design of an injection process involves the simultaneous consideration of plastic part design, mould design and injection moulding machine lection, production scheduling and cost as early as possible in the design stage.
This paper prents the basic structure of an injection mould design. The basis of this system aris from an analysis of the injection mould design process for mould design companies. This injection mould design system covers both the mould design process and mould knowledge management. Finally the principle of concurrent engineering process is outlined and then its principle is applied to the design of a plastic injection mould.
Keywords : Plastic injection mould design, Concurrent engineering, Computer aided
engineering, Moulding conditions, Plastic injection moulding, Flow simulation
1.Introduction
Injection moulds are always expensive to make, unfortunately without a mould it can not be possible ho have a moulded product. Every mould maker has his/her own approach to design a mould and there are many different ways of designing and building a mould. Surely one of the most critical para
meters to be considered in the design stage of the mould is the number of cavities, methods of injection, types of runners, methods of gating, methods of ejection, capacity and features of the injection moulding machines. Mould cost, mould quality and cost of mould product are inparable
In today’s completive environment, computer aided mould filling simulation packages can accurately predict the fill patterns of any part. This allows for quick simulations of gate placements and helps finding the optimal location. Engineers can perform moulding trials on the computer before the part design is completed. Process engineers can systematically predict a design and process window, and can obtain information about the cumulative effect of the process variables that influence part performance, cost, and appearance.
2.Injection Moulding新年诗句
Injection moulding is one of the most effective ways to bring out the best in plastics. It is universally ud to make complex, finished parts, often in a single step, economically, precily and with little waste. Mass production of plastic parts mostly utilizes moulds. The manufacturing process and involving moulds must be designed after passing through the appearance evaluation and the structure optimization of the product design. Designers face a huge number of options when they cre项目
ate injection-moulded components. Concurrent engineering requires an engineer to consider the manufacturing process of the designed product in the development pha. A good design of the product is unable to go to the market if its manufacturing process is impossible or too expensive. Integration of process
simulation, rapid prototyping and manufacturing can reduce the risk associated with moving from CAD to CAM and further enhance the validity of the product development.
The plastics industry is one of the world's fastest growing industry, belongs to a small number of hundreds of millions of dollars in industry. Almost all the supplies in their daily lives are inparable from the plastic and most can u plastic injection mold production. Injection molding injection molding process to take advantage of low-cost production of a variety of shapes and complex geometric patterns known . Injection molding injection molding process is a cyclic process. Can be divided into four key stages of packing, injection, cooling, demoulding. Plastic injection molding process begins to fill in the resin and the amount of additives to the hopper into the heating of the injection molding machine or injection system. Grain filling stage in injection temperature, the hot plastic melt into the mold cavity. The cavity is filled, the amount of molten plastic in the plastic solidification shrinkage caud by a higher compensation under the pressure of added. Followed by
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漫花之舞a cooling pha, the mold was cooled to a sufficient rigidity extrusion mold. Finally, the stripping stage, that is, open the mold and then the top part, and then together on the mold start the next cycle.The design and manufacture of injection molded plastic products with the expected performance is to rely on the experience of control of an expensive process, including the actual modification of the cover embosd. In mold design, design mold supplementary geometry, usually in the side of the core, including the complex projection and groove.Mold design must take into account many important design factor. The factors are the number and layout of the size of the mold cavity, runner system, gate systems, mold relea systems, and shrinkage.Thermal analysis of the mold, the main objective is to analyze the role of the residual thermal stress or pressure injection of product diameter direction. Heat flux density enhancements in the cooling pha of the molded parts, mainly becau of its low thermal conductivity and the temperature difference between the melting resin and mold. During cooling near the mold cavity will be non-uniform temperature region.During cooling, cooling
channels near the area than the area far from the cooling channels to cool faster. This temperature difference will cau uneven shrinkage of the material to heat stress. The strong thermal stress can cau warping problem. Therefore, it is an imitation of the important stage in the molded parts d
uring the cooling area of the thermal residual stress. Understand the characteristics of the thermal stress, causing deformation of pre-simulation.In this article, the injection mold is designed to produce warping of test samples and perform the thermal analysis prented in the mold on the role of the residual thermal stress. After the completion of the mold design and manufacture of, tryout injection warp specimens there are many defects. Including a short shot, splash and warping. The solution of a short shot by milling out the additional pores to drain the trapped air in the corner of the cavity. At the same time, reducing the injection pressure can reduce the occurrence of splashing. Warpage control can be controlled by many factors, such as injection time, injection temperature and dissolved material temperature.
复合文案After the trimming, mold can produce low-cost high-quality warp specimens, the specimens need to go through a simple polishing.
3.Importance of Computer Aided Injection Mould Design
逆战天赋The injection moulding design task can be highly complex. Computer Aided Engineering (CAE) analysis tools provide enormous advantages of enabling design engineers to consider virtually and part, mould and injection parameters without the real u of any manufacturing and time. The possib
ility of trying alternative designs or concepts on the computer screen gives the engineers the opportunity to eliminate potential problems before beginning the real production. Moreover, in virtual environment, designers can quickly and easily ass the nsitivity of specific moulding parameters on the quality and manufacturability of the final product. All theCAE tools enable all the analysis to be completed in a meter of days or even hours, rather than weeks or months needed for the real experimental trial and error cycles. As CAE is ud in the early design of part, mould and moulding parameters, the cost savings are substantial not only becau of best functioning part and time
savings but also the shortens the time needed to launch the product to the market.
The need to meet t tolerances of plastic part ties in to all aspects of the moulding process, including part size and shape, resin chemical structure, the fillers ud, mould cavity layout, gating, mould cooling and the relea mechanisms ud. Given this complexity, designers often u computer design tools, such as finite element analysis (FEA) and mould filling analysis (MFA), to reduce development time and cost. FEA determines strain, stress and deflection in a part by dividing the structure into small elements where the parameters can be well defined. MFA evaluates gate position and size to optimize resin flow. It also defines placement of weld lines, areas of excessive stress, and how wall and rib thickness affect flow. Other finite element design tools include mould co
oling analysis for temperature distribution, and cycle time and shrinkage analysis for dimensional control and prediction of frozen stress and warpage.
The CAE analysis of compression moulded parts is shown in Figure 1. The analysis cycle starts with the creation of a CAD model and a finite element mesh of the mould cavity. After the injection conditions are specified, mould filling, fiber orientation, curing and thermal history, shrinkage and warpage can be simulated. The material properties calculated by the simulation can be ud to model the structural behaviour of the part. If required, part design, gate location and processing conditions can be modified in the computer until an acceptable part is obtained. After the analysis is finished an optimized part can be produced with reduced weldline (known also knitline), optimized strength, controlled temperatures and curing, minimized shrinkage and warpage.
孕妇能吃黄豆吗Machining of the moulds was formerly done manually, with a toolmaker checking each cut. This process became more automated with the growth and widespread u of computer numerically controlled or CNC machining centres. Setup time has also been significantly reduced through the u of special software capable of generating cutter paths directly from a CAD data file. Spindle speeds as high as 100,000 rpm provide further advances in high speed machining. Cutting materials
