A RUNNER-GATE DESIGN SYSTEM FOR DIE CASTING DIES
Chang-Ho Kim *, Taek Hwan Kwon** * Dept. of Mechanical Engineering, Dong-Eui University, University, Kaya-Dong 24, Pusanjin-Ku, Pusan, Korea, 614-714 ** Graduate School, Dept. of Mechanical Design Engineering, P usan Nat'l University, #30 Jangjeon-Dong, Jangjeon-Dong, Kumjeong-Ku, Kumjeong-Ku, Pusan, Korea, 609-735
Abstract
Various analytical FEM, FDM tools for flow process including die casting have presented, they are only giving information to predetermined die design whether it is proper or not. Current shop floor practice uses the trial-and-error methods to determine new die design. This paper describes a research work of developing computer-aided die design system for die casting. Approach to the CAD system has been written in circumstance Auto LISP with personal computer. This system has been developed to present algorithms for automation of die design, especially runner-gate system using 3-D geometry. This system quantifies practical knowledge and experiences in die design as formulating procedure.
It is possible for engineers to make automatic and
efficient design of and it will result in reduction of required expenses and time. It is composed of selection of cast alloy, product design, runner-gate runner-gate design etc. In addition, specific rules and equations equations for the system have been presented. presented. An example is applied to cap-shaped cast using the proposed system.
Key words : Die casting, Die design system, Rule base, Runner, Gate
NOMENCLATURE NOMENCLATURE Qa
volume of cavity to be filled, cm3
V g
main gate velocity, m/sec
t g
filling time, sec
K
heat capacity per unit volume, cal
q'
the rate heat evolved per unit time during solidification, cal/sec
L
latent heat during solidification, cal/g
C p
specific heat of molten metal, cal/g¡ ¤ ¡ É
T m
temperature of molten metal, ¡ É
T s
solidus temperature, ¡ É
T d d
die temperature, ¡ É
¥ ñ
density of alloy, g/cm 3
S
radiation area, cm2
X
a half thickness of cast, cm
¥ ö
thermal conductivity of alloy, cal/cm ¡ ¤ sec¡ ¤ ¡ É
1. INTRODUCTION
Die casting is one of the most economical casting processes for manufacturing precision shaped parts in mass production. It is a precise casting method in which molten metal is injected at high pressure into a die cavity. As soon as the molten metal has filled the cavity, it solidifies by fast cooling. Die-cast components are being used increasingly in the automobile, aerospace, electronic and other industries because of their premium quality, low cost and low weight. Because of high pressure and short cycle times involved, thin-wall sections are possible. In die-design system of various forming processes, Shaffer developed progressive die design by computer (PDDC) system and J.P. Kruth made efforts to develop an integrated CAD/CAM system for mould design and manufacture. J.C. Choi developed a compact and practical CAD system for blanking or piercing of irregular shaped- sheet metal products and statorrotor parts. In studies of die casting process, C.C Thai used runner-optimization design method and the abductive network in modeling the die casting process according to the experimental data. W. Zhang researched the CAD/ CAE system that die designer can determine the shape and dimension of runner-gating system under different casting condition. Generally speaking, die designer still have to depend on engineer’s experiences and know-how due to lack of proper analytical ability metal flow and velocity and heat transfer in die. Current shop floor practice uses the trial-and-error method to determine die design, when new moulds are used. This method is costly and results in a lot of wasted casting. To solve this problem a study was done on the runner and gate system to simulate the molten metal flow and to analyze the pressure and metal movement during casting process. Although some finite element analysis software is capable of analyzing the melting process and flow conditions of the products (workpiece) under various injection conditions, they are only giving some limited suggestions and information to die design. In this study, die design system for die casting process has been developed to present flow chart for automation of die design, especially runner-gate system. In addition, specific rules and equations for runner-gate system have been presented to avoid too many trials and errors with expensive equipment. It is possible for engineers to make an automatic and efficient die design and it will result in reduction of expense and time.
2. STRUCTURE OF CASTING PRODUCT AND DIE
An example of cast product is seen in Fig.1. It is generally composed of cast cavity, gate, runner, biscuit, overflow and to be formed out from die. Irrespective of the shape of the cast, the quality is always determined by the runner-gate system. Generally, the system contains their arrangements and shapes to design properly. The effects of metal velocity and die temperature on the metal flow distance and quality are discussed.
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Schaffer, G. Computer Aided Design of Progressive Dies. American Machinist
1971 ,
22, 73-75.
Kruth, J.P. Steps Toward an Integrated CAD/CAM System for Mould Design and Manufacture: Anisotropic Shrinkage, Component Library and Link to NC Machining and EDM . Annals of the CIRP
1986,
35-38.
Abrahams, M. ; Doble, M. CAD/CAM Integration for Producing Injection Moulds . ZWF Z. Wirtsch. Fertigung
1985,
80 (9),
60-62. Choi, J.C. ; Kim, B.M. ; Cho, H.Y. ; Kim, C. A Compact and Practical CAD System for Blanking or Piercing of Irregular shaped Sheet Metal Products and Stator and Rotor Parts. Inter. J. of Machine Tool & Manufacture
1998,
931-963.
Thai, C.C. ; Lim, J.C. A Runner-optimization Design Study of a Die-casting Die. Journal of Materials Processing Technology 1998,
84,1-12
Thai, C.C. ; Lim, J.C. The Optimal Position for the Injection Gate of a Die-casting Die . Journal of Materials Processing Technology
1999,
86, 87-100
Zhang, W. ; Xiong, S. ; Liu, B. Study on a CAD/CAM System of Die Casting . Journal of Materials Processing Technology 1997,
63, 707-711.
Sulaiman, S. ; Keen, T.C. Flow Analysis along the Runner and Gating System of a Casting Process. Journal of Materials Processing Technology
1997,
63, 690-695.
Schaffer, G. Computer Aided Design of Progressive Dies. American Machinist
1971 ,
22, 73-75.
Kruth, J.P. Steps Toward an Integrated CAD/CAM System for Mould Design and Manufacture: Anisotropic Shrinkage, Component Library and Link to NC Machining and EDM . Annals of the CIRP
1986,
35-38.
Abrahams, M. ; Doble, M. CAD/CAM Integration for Producing Injection Moulds . ZWF Z. Wirtsch. Fertigung
1985,
80 (9),
60-62. Choi, J.C. ; Kim, B.M. ; Cho, H.Y. ; Kim, C. A Compact and Practical CAD System for Blanking or Piercing of Irregular shaped Sheet Metal Products and Stator and Rotor Parts. Inter. J. of Machine Tool & Manufacture
1998,
931-963.
Thai, C.C. ; Lim, J.C. A Runner-optimization Design Study of a Die-casting Die. Journal of Materials Processing Technology 1998,
84,1-12
Thai, C.C. ; Lim, J.C. The Optimal Position for the Injection Gate of a Die-casting Die . Journal of Materials Processing Technology
1999,
86, 87-100
Zhang, W. ; Xiong, S. ; Liu, B. Study on a CAD/CAM System of Die Casting . Journal of Materials Processing Technology 1997,
63, 707-711.
Sulaiman, S. ; Keen, T.C. Flow Analysis along the Runner and Gating System of a Casting Process. Journal of Materials Processing Technology
1997,
63, 690-695.
