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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of Materials Processing
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Journal DOI :
The Korean Society for Technology of Plasticity
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Volume & Issues
Volume 7, Issue 6 - Dec 1998
Volume 7, Issue 5 - Oct 1998
Volume 7, Issue 4 - Aug 1998
Volume 7, Issue 3 - Jun 1998
Volume 7, Issue 2 - Apr 1998
Volume 7, Issue 1 - Feb 1998
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Prediction of the Behavior of dynamic Recrystallization in Inconel 718 during Hot Forging using Finite Element Method
Choi, Min-Shik ; Kang, Beom-Soo ; Yum, Jong-Taek ; Park, Noh-Kwang ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 197~206
This paper presents the prediction of dynamic recrystallization behavior during hot forging of Inconel 718. Another experiment of pancake forging was also carried out to examine the recrystallization ration dynamically recrystallizaed grain size, and grain growth in the forging. In experiments cylindrical billets were forged by two operations with variations of forging temperature, reduction ration of deformation. and preheating process at each forging step. Also the finite element program, developed here for the prediction using the metallurgical models was used for the analysis of to Inconel 718 upsetting and the results were compared with experimental ones.
Optimization of Superplastic Forming Process
Lee, Jeong-Min ; Hong, Seong-Seok ; Kim, Yong-Hwan ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 207~214
Influence of final thickness distribution in superplastic forming processes on mechanical properties of the product becomes very crucial. We should improve the thickness distribution of products by combining process parameters adequately In this paper we adopt a non-linear optimization technique for optimal process design of superplastic forming. And optimum design variable which makes the most adequate thickness distribution in combined stretc/blow forming and blow forming is predicted by this optimization scheme and rigid-viscoplastic finite element method.
Effect of Reheating Conditions of Semi-Solid Aluminum Alloy on Globular Microstructure
Gang, Seong-Su ; Gang, Chung-Gil ; Do, Yeong-Jin ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 215~224
A semi-solid forming has a lot of advantages compared to the die casting. squeeze casting and conventional forging. therefore, semi-solid forming process is now becoming industrial interest for the production of metal components and metal matrix composites. However the material behaviour in the semi-solid temperature range is not sufficiently known although it controls the whole process through forces and geometry evolutions because the behaviour of metal slurries is complex. The semi-solid materials(SSMs) fabricated under electric-magnetic stirring condition is necessary to be applicated in forming process. A reheating conditions were studied with the reheating time holding time and reheating temperatures. The microstructure of SSM(specimen size : d39
h85) at the condition of heating time 10min and heating temperature 590
is the most globular and finest one. The microstructure of SSM(specimen size : d76
h60) reheated under the three step reheating conditions is most globular and finest.
A Case Study on the Process Planning for Multi-Stepped Deep Drawing of Complex Circular Shells
Kim, Doo-Hwan ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 225~232
This article is aimed primarily at establishing a process planning method for complex circular shells. For the deep drawing of complex shaped shell, the optimum process design is required to reduce the trial cost improve the quality, increase the productivity and shorten the delivery. The present approach which is related to the optimum process planning is based on the empirical knowledge through trial and error in the industrial field. In order to check the validity and the effectiveness of proposed work a sample process design has been applied to the multi-stepped deep drawing of com-plex shell considering the process variables such as drawing rate radius and blank development. In particular the difference between the limiting drawing rate and to optimum drawing rate has been discussed and the usefulness of present suggestion has been shown.
Elastic-Plastic Implicit Finite Element Method Considering Planar Anisotropy for Complicated Sheet Metal Forming Processes
Yun, Jeong-Hwan ; Kim, Jong-Bong ; Yang, Dong-Yeol ; Jeong, Gwan-Su ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 233~245
A new approach has been proposed for the incremental analysis of the nonsteady state large deformation of planar anisotropic elastic-plastic sheet forming. A mathematical brief review of a constitutive law for the incremental deformation theory has been presented from flow theory using the minimum plastic work path for elastic-plastic material. Since the material embedded coordinate system(Lagrangian quantity) is used in the proposed theory the stress integration procedure is completely objective. A new return mapping algorithm has been also developed from the general midpoint rule so as to achieve numerically large strain increment by successive control of yield function residuals. Some numerical tests for the return mapping algorithm were performed using Barlat's six component anisotropic stress potential. Performance of the proposed algorithm was shown to be good and stable for a large strain increment, For planar anisotropic sheet forming updating algorithm of planar anisotropic axes has been newly proposed. In order to show the effectiveness and validity of the present formulation earing simulation for a cylindrical cup drawing and front fender stamping analysis are performed. From the results it has been shown that the present formulation can provide a good basis for analysis for analysis of elastic-plastic sheet metal forming processes.
A Progressive Automated-Process Planning and Die Design and Working System for Blanking or Piercing and Bending of Sheet Metal Product
Choe, Jae-Chan ; Kim, Chul ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 246~259
This paper describes a research work of developing a computer-aided design and manufacturing of irregular shaped sheet metal product for blanking or piercing and bending operations. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts, This system has been written in AutoLISp on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules which are input and shape treatment, flat pattern-layout, pro-processor module. Based on the knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product complexities of blank geometry and punch profile sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing and bending die in this field.
Optimum Blank Design of Automobile Sub-Frame
Kim, Jong-Yop ; Kim, Nak-Soo ; Heo, Man-Seong ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 260~273
A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between final deformed shaped and target contour shape into account. Based on the method a computer program composed of blank design module FE-analysis program and mesh generation module is developed. The rollback method is applied to square cup drawing process with the flange of unifiorm size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary square blank after three modification. Good agreements are recognized between the numerical results and the published results for initial blank shape and thickness strain distribution. The optimum blank shape for two parts of automobile sub-frame is designed, The thickness distribution and the level of punch load is improved. Also the method is applied to design the weld line in the tailor-welded blank. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.
A Study on Die Wear Model considering Thermal Softening(I) -Construction of Wear Model
Kang, Jong-Hun ; Park, In-Woo ; Jae, Jin-Soo ; Kang, Seong-Soo ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 274~281
The service life of tools in metal forming process is to a large extent limited by wear, fatigue fracture and plastic deformation. In elevated temperature forming processes wear is the predominant factor for tool operating life. To predict tool life by wear Achard's model is generally applied. Usually hardness of die is considered to be a function of temperature. But hardness of die is a function of not only tem-perature but also operating time of die. To consider softening of die by repeated operation it is necessary to express hardness of die by a function of a function of temperature and time. By experiment of reheating of die softening curve was obtained and applied to suggest modified Archard's Model in which hardness is a function of main tempering curve.
A Study on Die Wear Model considering Thermal Softening(II) -Application of Suggested Wear Model
Kang, Jong-Hun ; Park, In-Woo ; Jae, Jin-Soo ; Kang, Seong-Soo ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 282~290
In bulk metal forming processes prediction of tool life is very important for saving production cost and achieving good material properties. Generally the service life of tools in metal forming process is limited to a large extent by wear, fracture and plastic deformation of tools. In case of hot and warm forging processes tool life depends on wear over 70%. In this study finite element analyses are con-ducted to warm and hot forging by adopting suggested wear model. By comparison of simulation and eal profile of die suggested wear model. By comparison of simulation and real profile of die suggested model is verified.
Development of a Finisher Design System for Axisymmetic Hot Steel Forging
Kim, Dae-Young ; Park, Jong-Jin ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 291~297
A forging product in general is made through buster blocker and finisher processes. The dies used in these processes are designed by experienced forging engineers. In the present study an expert system is developed for the finisher die design of axisymmetric hot steel forging. It is a rule based system written in Fortran and AutoLISp operating on a personal computer. In this paper major rules consid-ered in the system are summarized and the capabilities of the system are examined through several examples.
Development of a Blocker Design System for Axisymmetric Hot Steel Forging
Kim, Dae-Young ; Park, Jong-Jin ;
Transactions of Materials Processing, volume 7, issue 3, 1998, Pages 298~305
In hot forging the blocker is a transient shape between the buster and the finisher, In general as the finisher shape becomes complicated the blocker design becomes quite difficult. In the present study an expert system is developed for the blocker die design of axisymmetric hot steel forging. It is a rule based system written in Fortran and AutoLISP operating on a personal computer. In this paper the major rules considered in the system are summarized and several blockers designed by the system are discussed with results of rigid viscoplastic finite element analysis.