Heat Treatment of Die and Mould Oriented Concurrent Design LI Xiong,ZHANG Hong-bing,RUAN Xue—yu,LUO Zhong—hua,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 semi—experience，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 life．Design and manufacture of die and mould have progressed rapidly，but heat treatment lagged seriously behind them．As die and mould industry develops，heat treatment must ensure die and mould there are good state of manufacture，assembly and wear—resistant properties by request. Impertinent heat treatment can influence die and mould manufacturing such as over—hard and—soft and assembly．Traditionally 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 error．The concurrent pattern has dismissed the defect of serial pattern,which bring about a revolution against serial pattern． In the present work．the 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 Fig．1). 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 backwards．Meanwhile，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 foreground．Whereas 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 purchasers．This 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 designing．In 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 CAD／CAE for Die and Mould It can be seen from Fig．2 that the process design and simulation of heat treatment are the core of integration frame．After 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 heat—treatment 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 technology．Moreover 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 mould．Modeling 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 etc．For example，3-D heat—conducting algorithm models for local heating complicated impression and asymmetric die and mould，and M ARC software models for microstructure transformation was used．Computer 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 field．If 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 determined．It is difficult to determine the parameters by computer fully．Since computer technology develops quickly in recent decades,the difficulty with large—scale calculation has been overcome．By simulating and weighing the property，the cost and the required period after heat treatment．it is not difficult to optimize the heat treatment process． 2.3 Data base for heat treatment A heat treatment database is described in Fig． 3．The database is the foundation of making out heat treatment process．Generally，heat treatment database is divided into materials database and process database．It is an inexorable trend to predict the property by materials and process．Although it is difficult to establish a property database，it is necessary to establish the database by a series of tests．The materials database includes steel grades,chemical compositions，properties and home and abroad grades parallel tables．The process database includes heat treatment criterions，classes，heat preservation time and cooling velocity．Based 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 CAD／CAE system transfers the information about design and manufacture to the numerical control device．Through rapid tooling prototype， the reliability of tool and the clamping apparatus can be judged．The whole procedure is transferred by network，in which there is no man—made interference． 3 Key Technique 3.1 Coupling of temperature，microstructure，stress and property Heat treatment procedure is a procedure of temperature-microstructure—stress interaction．The three factors can all influence the property (see Fig．4) ．During heating and cooling，hot stress and transformation will come into being when microstructure changes.Transformation temperature-microstructure and temperature—microstructure—and stress-property interact on each other．Research on the interaction of the four factors has been greatly developed,but the universal mathematic model has not been built．Many models fit the test nicely，but they cannot be put into practice．Difficulties 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 on．They should have own database and mode1．They are in series with each other by the entity—relation model．Through establishing and employing dynamic inference mechanism ， the aim of optimizing design can be achieved．The relation between product model and other models was built．The product model will change in case the cell model changes． In fact，it belongs to the relation of data with die and mould．After 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 system．After 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 groups．Because each member is short of global consideration for die and mould development， they need to be managed and harmonized．Firstly,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 conflict．Secondly，development plan should be made out and monitor mechanism should be established．The obstruction can be duly excluded in case the development is hindered． Agile management and harmony redound to communicating information， increasing efficiency，and reducing redundancy．Meanwhile 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 platform．When 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-hong．The Theory and Technique of Modern Die and Mould Design and Manufacture[M]．Shanghai：Shanghai Jiaotong University Press 2000(in Chinese)． [2] Kang M，Park& Computer Integrated Mold Manufacturing[J]．Int J Computer Integrated Manufacturing，1995，5：229-239． [3] Yau H T， Meno C H．Concurrent Process Planning for Finishing Milling and Dimensional Inspection of Sculptured Surface in Die and Mould Manufacturing[J]．Int J Product Research，1993，31(11)：2709—2725． [4] LI Xiang，ZHOU Xiong-hui，RUAN Xue-yu．Application of Injection Mold Collaborative Manufacturing System [J]．JournaI of Shanghai Jiaotong University，2000，35(4) ： 1391-1394． [5] Kuzman K，Nardin B，Kovae M ,et a1．The Integration of Rapid Prototyping and CAE in Mould Manufacturing [J]．J Materials Processing Technology，2001，111： 279—285． [6] LI Xiong，ZHANG Hong—bing，RUAN Xue-yu，et a1．Heat Treatment Process Design Oriented Based on Concurrent Engineering[J]．Journal of Iron and Steel Research，2002，14(4)：26—29． 文獻(xiàn)出處： LI Xiong,ZHANG Hong-bing,RUAN Xue—yu,LUO Zhong—hua,ZHANG Yan. Heat Treatment of Die and Mould Oriented Concurrent Design[J]. Journal of Iron and Steel Research，2006,13(1): 40-43，74