1、PDF外文：http:/ 1 附录 The Optimal Design of a Cooling System for a Die-Casting Die With a Free Form Surface Abstract This study is on the finite element and abductive networkmethod application to die-casting dies with free-form surfaces.The study aims to find the optimal cooling system param
2、etersand decrease in deformation of a die-casting die. In order toavoid the numerous influencing factors, the free-form surfaceof a die-casting die is created as a non-linear Eq. of apolynomial function. The parameters of the cooling system,including the channel space and channel diameter, are adjus
3、tedaccording to the non-linear Eq. An abductive network has been built for modelling the diecastingcooling parameters. The abductive network is composedof a number of functional nodes. Once the cooling systemparameters are given, this network can predict the deformationof the die-casting accurately.
4、 A simulated annealing optimizationalgorithm with a performance index is then applied tothe neural network for searching for the optimal cooling systemparameters and to obtain a satisfactory result. Keywords： Die-casting die； Free-form； Neural network； Simulatedannealing 1. Introduction The ty
5、pical, traditional die-casting process includes high-pressurefilling, cooling, solidification and ejection stages. The coolingstage is of great importance because it significantly affectsboth the productivity and the quality of the die-cast part. It iswell known that about 80% of the cycle time of d
6、ie-castingis spent in cooling the hot melt sufficiently so that the castpart can be ejected without warp. The design of a successfuldie can be considerably affected by perfect filling, whichreduces the cooling time, reduces warp and in turn increasesthe quality of the part. The main aim of the
7、;2 cooling processis to maintain a uniform temperature of the filling and cooling cycle. Accordingly, there are at least two important conceptsfor the designer when considering the cooling system and inestablishing cooling processing conditions: (1) achieving uniformtemperature and. (2) mini-m
8、ising the cycle time. To achieve these two aims, the designer may need an optimalcomputer-aided design system to achieve a rapid and uniformcooling system. The design of an optimal system needs analysisof 3D heat transfer during the filling and cooling processes.The thermal analysis tool should pred
9、ict the temperature gradientand deformation of the die-body. Generally speaking, traditional die design still depends onexperience, due to the lack of analytic ability in mould flowand heat transfer, so the designer is unable to evaluate andhandle the deformation resulting from material and thermale
10、xpansion and shrinkage of the die. The parameters of differentcooling systems can cause large temperature gradients, anddifferent deformations. Although FEM software is capable of analysing the fillingflowand coolingconditions of pressure-injected metal and theheat stress, heat strain and temperatur
11、e distribution conditionsof a die-casting die under various cooling systems, the establishmentof an analytic model is very difficult, especiallyfor 3D free-form geometry. Besides understanding therequirements of multi-cavity dies, and the metal flow andsolidification process, the designer should be
12、fullyacquaintanted with the basic finite element software. Integrationcan be achieved and can save a lot of money and time onlyif a complete understanding of the process of die manufacturingis available and eliminate the annoyance caused by movingof personnel. Initially, consider the design of the v
13、ent gate and overflowgate in the process of injection and flow to fill the die cavityduring cold room die-casting as investigated by simulation byGarber 2. When metal casting using a plunger into a cavity,he considered the change occurring in the metal, and thereplacement of the air in the cavity by
14、 molten metal. Subsequently,Garber 3,4 showed that too large or too small aplunger speed will affect the cast quality. Groenevelt andKaiser 5 studied and discussed the influence of the speed ofinjection of the molten metal into the cavity, and flow distanceand cavity temperature on the quality of pr
15、oduct after casting.According to the experiment, the distance of molten metalflow increases linearly as the die-casting speed increases, asdoes the die temperature. The range of temperature is approximately121288C. Other studies 6,7 proposed the importanceof initial temperature (pre-heat temperature
16、) of the die, andpointed out that too low a pre-heat 3 temperature would tend tocause failure in filling up the cavity inside the die by thedie-casting liquid, and result in formation failure. A highertemperature may increase the cooling time and reduce productivity.Truelove 8 used a cooling s
17、ystem to control theoverall temperature of the die, in order to obtain an optimalheat transmission characteristic, and reduce the occurrence ofhard pointphenomena in the cast piece, thereby improving thequality of the piece. Jong et al. 9 developed a mathematical Eq. for the flowand solidification o
18、f molten metal during high-pressure diecasting,in order to analyse the temperature conditions andsolidification strain of die-cast components in the cavity. Kenichiro et al. 10 used a finite element method to analyseand design the die； the result was not only improved accuracy,but the factors to be
19、considered are increased too, and thepressure of die-casting, the speed of molten liquid flow, viscosity,and the mechanical nature of the material changed withtemperature and phase. This study uses CADCAE error software for a systemicdesign process of a die, in order to minimise human error indie de
20、sign 1113. It uses the CAD software to create a freeformmodel, and the finite element software to analyse theconditions of die-cast processing. It simulates the temperaturedistribution of the die-body and deformation after casting undervarious parameters (cooling-line distance R, channel centerdista
21、nce L, channel diameter D), as shown in Fig. 1. Ituses an abductive network to establish the relationship of theFig. 1. Relationship between cooling channel and free-form die.deformation and the cooling system parameters model. Basedon the abductive modelling technique, it is able to representthe co
22、mplicated and uncertain relationships between the inputand the output variables. Once the abductive network has constructed the relationshipsof the input and output die-casting variables, an appropriateoptimisation algorithm with a performance index is able tosearch for the optimal casting parameter
23、s. In this paper, asound optimisation method of simulated annealing 14 isadopted. The simulated annealing algorithm is a simulation ofthe annealing process for minimising the performance index.It has been successfully applied to die-casting die design 15,etc. The basic theory can be widely applied. 2. Die-Casting Flow Theory In the die-casting process about 80% of the time is spent incooling cycle. The deformation of the die-casting die is causedby the non-uniform temperature distribution of the castingprocessing, which affects the quality of casting part. Thedesigner of the
