英文原文
CONCURRENT DESIGN OF PLASTICS INJECTION MOULDS Assist.Prof.Dr. A. Y A YLA /Prof.Dr. Paş a Y A YLA梦到被抢劫
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 integrat
ion 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 stag
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 princ iple 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
色波波天下的近义词1.Introductio
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 mou
岳母的故事ld and there are many different ways of designing and building a mould. Surely one of the most critical parameters 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
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 invol
ving 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 create 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.
3.Importance of Computer Aided Injection Mould Design
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 possibility 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.
网名大全英文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 cooling analysis for temperature distribution, and cycle time and shrinkage analysis for dimensional control and prediction of frozen stress and warpage.
八娃老姥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. 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 have demonstrated phenomenal performance without the u of any cutting/coolant fluid whatsoever. As a result, the process of machining complex cores and cavities has been accelerated.
It is good news that the time it takes to generate a mould is constantly being reduced. The bad news, on the other hand, is that even with all the advances, designing and manufacturing of the mould can still take a long time and can be extremely expensive.
Figure 1 CAE analysis of injection moulded parts
胆囊炎什么症状Many company executives now realize how vital it is to deploy new products to market rapidly. New products are the key to corporate prosperity. They drive corporate revenues, market shares, bottom lines and share prices. A company able to launch good quality products with reasonable prices ahead of their competition not only realizes 100% of the market before rival products arrive but also tends to maintain a dominant position for a few years even after competitive products have finally been announced (Smith, 1991). For most products, the two advantages are dramatic. Rapid product development is now a key aspect of competitive success. Figure 2 shows that only 3–7% of the product mix from the average industrial or electronics company is less than 5 years old. For companies in the top quartile, the number increas to 15–25%. For world-class firms, it is 60–80% (Thompson, 1996). The best companies continuously develop new products. At Hewlett-Packard, over 80% of the profits result from products less than 2 years old! (Neel, 1997)
Figure 2. Importance of new product (Jacobs, 2000)
With the advances in computer technology and artificial intelligence, efforts have been directed to reduce the cost and lead time in the design and manufacture of an injection mould. Injection mould design has been the main area of interest since it is a complex process involving veral sub-designs related to various components of the mould, each requiring expert knowledge and experience. Lee et. al. (1997) propod a systematic methodology and knowledge ba for injection mould design in a concurrent engineering environment.
4.Concurrent Engineering in Mould Design
Concurrent Engineering (CE) is a systematic approach to integrated product development process. It reprents team values of co-operation, trust and sharing in such a manner that decision making is by connsus, involving all per spectives in parallel, from the very beginning of the product life-cycle (Evans, 1998). Esntially, CE provides a collaborative, co-operative, collective and simultaneous engineering working environment. A concurrent engineering approach is bad on five key elements:
1.process
2.multidisciplinary team
3. integrated design model
4. facility
5. software infrastructure
