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Heat Treatment of Die and Mould Oriented Concurrent Design LI Xiong,ZHANG Hong-bing,RUAN Xueyu,LUO Zhonghua,ZHANG Yan Abstract: Many disadvantages exist in the traditional die design method which belongs to serial pattern. It is well known that heat treatment is highly important to the dies. A new idea of concurrent design for heat treatment process of die and mould was developed in order to overcome the existent shortcomings of heat treatment process. Heat treatment CAD/CAE was integrated with concurrent circumstance and the relevant model was built. These investigations can remarkably improve efficiency, reduce cost and ensure quality of R and D for products. Key words:die design; heat treatment; mould Traditional die and mould design,mainly by experience or semiexperience,is isolated from manufacturing process.Before the design is finalized,the scheme of die and mould is usually modified time and again, thus some disadvantages come into being,such as long development period,high cost and uncertain practical effect.Due to strong desires for precision,service life,development period and cost,modern die and mould should be designed and manufactured perfectly.Therefore more and more advanced technologies and innovations have been applied,for example,concurrent engineering,agile manufacturing virtual manufacturing,collaborative design,etc. Heat treatment of die and mould is as important as design,manufacture and assembly because it has a vital effect on manufacture,assembly and service lifeDesign and manufacture of die and mould have progressed rapidly,but heat treatment lagged seriously behind themAs die and mould industry develops,heat treatment must ensure die and mould there are good state of manufacture,assembly and wearresistant properties by request. Impertinent heat treatment can influence die and mould manufacturing such as overhard andsoft and assemblyTraditionally the heat treatment process was made out according to the methods and properties brought forward by designer This could make the designers of die and mould and heat treatment diverge from each other,for the designers of die and mould could not fully realize heat treatment process and materials properties,and contrarily the designers rarely understood the service environment and designing thought. These divergences will impact the progress of die and mould to a great extent. Accordingly,if the process design of heat treatment is considered in the early designing stage,the aims of shortening development period,reducing cost and stabilizing quality will be achieved and the sublimation of development pattern from serial to concurrent will be realized Concurrent engineering takes computer integration system as a carrier,at the very start subsequent each stage and factors have been considered such as manufacturing,heat treating,properties and so forth in order to avoid the errorThe concurrent pattern has dismissed the defect of serial pattern,which bring about a revolution against serial pattern In the present workthe heat treatment was integrated into the concurrent circumstance of the die and mould development, and the systemic and profound research was performed 1 Heat Treatment Under Concurrent Circumstance The concurrent pattern differs ultimately from the serial pattern(see Fig1). With regard to serial pattern,the designers mostly consider the structure and function of die and mould,yet hardly consider the consequent process,so that the former mistakes are easily spread backwardsMeanwhile,the design department rarely communicates with the assembling,cost accounting and sales departments These problems certainly will influence the development progress of die and mould and the market foregroundWhereas in the concurrent pattern,the relations among departments are close,the related departments all take part in the development progress of die and mould and have close intercommunion with purchasersThis is propitious to elimination of the conflicts between departments, increase the efficiency and reduce the cost Heat treatment process in the concurrent circumstance is made out not after blueprint and workpiece taken but during die and mould designingIn this way,it is favorable to optimizing the heat treatment process and making full use of the potential of the materials 2 Integration of Heat Treatment CADCAE for Die and Mould It can be seen from Fig2 that the process design and simulation of heat treatment are the core of integration frameAfter information input via product design module and heat treatment process generated via heat treatment CAD and heat treatment CAE module will automatically divide the mesh for parts drawing,simulation temperature field microstructure analysis after heattreatment and the defect of possible emerging (such as overheat,over burning),and then the heat treatment process is judged if the optimization is made according to the result reappeared by stereoscopic vision technologyMoreover tool and clamping apparatus CAD and CAM are integrated into this system The concurrent engineering based integration frame can share information with other branch That makes for optimizing the heat treatment process and ensuring the process sound 2.1 3-D model and stereoscopic vision technology for heat treatment The problems about materials,structure and size for die and mould can be discovered as soon as possible by 3-D model for heat treatment based on the shape of die and mouldModeling heating condition and phase transformation condition for die and mould during heat treatment are workable,because it has been broken through for the calculation of phase transformation thermodynamics,phase transformation kinetics,phase stress,thermal stress,heat transfer,hydrokinetics etcFor example,3-D heatconducting algorithm models for local heating complicated impression and asymmetric die and mould,and M ARC software models for microstructure transformation was usedComputer can present the informations of temperature,microstructure and stress at arbitrary time and display the entire transformation procedure in the form of 3-D by coupling temperature field,microstructure field and stress fieldIf the property can be coupled,various partial properties can be predicted by computer 2.2 Heat treatment process design Due to the special requests for strength,hardness,surface roughness and distortion during heat treatment for die and mould,the parameters including quenching medium type, quenching temperature and tempering temperature and time,must be properly selected,and whether using surface quenching or chemical heat treatment the parameters must be rightly determinedIt is difficult to determine the parameters by computer fullySince computer technology develops quickly in recent decades,the difficulty with largescale calculation has been overcomeBy simulating and weighing the property,the cost and the required period after heat treatmentit is not difficult to optimize the heat treatment process 2.3 Data base for heat treatment A heat treatment database is described in Fig 3The database is the foundation of making out heat treatment processGenerally,heat treatment database is divided into materials database and process databaseIt is an inexorable trend to predict the property by materials and processAlthough it is difficult to establish a property database,it is necessary to establish the database by a series of testsThe materials database includes steel grades,chemical compositions,properties and home and abroad grades parallel tablesThe process database includes heat treatment criterions,classes,heat preservation time and cooling velocityBased on the database,heat treatment process can be created by inferring from rules 2.4 Tool and equipment for heat treatment After heat treatment process is determined,tool and equipment CADCAE system transfers the information about design and manufacture to the numerical control deviceThrough rapid tooling prototype, the reliability of tool and the clamping apparatus can be judgedThe whole procedure is transferred by network,in which there is no manmade interference 3 Key Technique 3.1 Coupling of temperature,microstructure,stress and property Heat treatment procedure is a procedure of temperature-microstructurestress interactionThe three factors can all influence the property (see Fig4) During heating and cooling,hot stress and transformation will come into being when microstructure changes.Transformation temperature-microstructure and temperaturemicrostructureand stress-property interact on each otherResearch on the interaction of the four factors has been greatly developed,but the universal mathematic model has not been builtMany models fit the test nicely,but they cannot be put into practiceDifficulties with most of models are solved in analytic solution,and numerical method is employed so that the inaccuracy of calculation exists Even so,comparing experience method with qualitative analysis,heat treatment simulation by computer makes great progress 3.2 Establishment and integration of models The development procedure for die and mould involves design,manufacture,heat treatment,assembly,maintenance and so onThey should have own database and mode1They are in series with each other by the entityrelation modelThrough establishing and employing dynamic inference mechanism , the aim of optimizing design can be achievedThe relation between product model and other models was builtThe product model will change in case the cell model changes In fact,it belongs to the relation of data with die and mouldAfter heat treatment model is integrated into the system,it is no more an isolated unit but a member which is close to other models in the systemAfter searching,calculating and reasoning from the heat treatment database,procedure for heat treatment,which is restricted by geometric model,manufacture model for die and mould and by cost and property,is obtained If the restriction is disobeyed, the system will send out the interpretative warning All design cells are connected by communication network 3.3 Management and harmony among members The complexity of die and mould requires closely cooperating among item groupsBecause each member is short of global consideration for die and mould development, they need to be managed and harmonizedFirstly,each item group should define its own control condition and resource requested,and learn of the request of up-and-down working procedure in order to avoid conflictSecondly,development plan should be made out and monitor mechanism should be establishedThe obstruction can be duly excluded in case the development is hindered Agile management and harmony redound to communicating information, increasing efficiency,and reducing redundancyMeanwhile it is beneficial for exciting creativity,clearing conflict and making the best of resource 4 Conclusions (1) Heat treatment CAD CAE has been integrated into concurrent design for die and mould and heat treatment is graphed,which can increase efficiency,easily discover problems and clear conflicts (2) Die and mould development is performed on the same platformWhen the heat treatment process is made out,designers can obtain correlative information and transfer self-information to other design departments on the platform (3) Making out correct development schedule and adjusting it in time can enormously shorten the development period and reduce cost References: 1 ZHOU Xiong-hui,PENG Ying-hongThe Theory and Technique of Modern Die and Mould Design and ManufactureMShanghai:Shanghai Jiaotong University Press 2000(in Chinese) 2 Kang M,Park& Computer Integrated Mold ManufacturingJInt J Computer Integrated Manufacturing,1995,5:229-239 3 Yau H T, Meno C HConcurrent Process Planning for Finishing Milling and Dimensional Inspection of Sculptured Surface in Die and Mould ManufacturingJInt J Product Research,1993,31(11):27092725 4 LI Xiang,ZHOU Xiong-hui,RUAN Xue-yuApplication of Injection Mold Collaborative Manufacturing System JJournaI of Shanghai Jiaotong University,2000,35(4) : 1391-1394 5 Kuzman K,Nardin B,Kovae M ,et a1The Integration of Rapid Prototyping and CAE in Mould Manufacturing JJ Materials Processing Technology,2001,111: 279285 6 LI Xiong,ZHANG Hongbing,RUAN Xue-yu,et a1Heat Treatment Process Design Oriented Based on Concurrent EngineeringJJournal of Iron and Steel Research,2002,14(4):2629 文獻(xiàn)出處: LI Xiong,ZHANG Hong-bing,RUAN Xueyu,LUO Zhonghua,ZHANG Yan. Heat Treatment of Die and Mould Oriented Concurrent DesignJ. Journal of Iron and Steel Research,2006,13(1): 40-43,74