The Experts below are selected from a list of 3024 Experts worldwide ranked by ideXlab platform

H.y. Lu - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of air back pressure in Die-casting Dies
    Journal of Materials Processing Technology, 1999
    Co-Authors: H.y. Lu
    Abstract:

    Abstract In high-pressure Die-casting, molten metal is injected into a Die Cavity at a high velocity. The metal entering into the Cavity expels the air from the Cavity through the vents. Air back pressure will be created when the volume of metal flow exceeds the volume of air escaping out of the Die Cavity. A new mathematical model is proposed for the calculation of the creation of the back pressure in a Die Cavity. Air discharge through vents is modeled by the Poiseuille flow. The differential equation of the time rate of change of the back pressure is derived. The creation of the back pressure is correlated with the configuration sizes of the vent, and computations are carried out for different configurations of the vent geometry.

  • Modeling of air back pressure in Die-casting Dies
    Journal of Materials Processing Technology, 1999
    Co-Authors: H.y. Lu
    Abstract:

    In high-pressure Die-casting, molten metal is injected into a Die Cavity at a high velocity. The metal entering into the Cavity expels the air from the Cavity through the vents. Air back pressure will be created when the volume of metal flow exceeds the volume of air escaping out of the Die Cavity. A new mathematical model is proposed for the calculation of the creation of the back pressure in a Die Cavity. Air discharge through vents is modeled by the Poiseuille flow. The differential equation of the time rate of change of the back pressure is derived. The creation of the back pressure is correlated with the configuration sizes of the vent, and computations are carried out for different configurations of the vent geometry.Department of Industrial and Systems Engineerin

  • A computer simulation of the effect of wall thickness on the metal flow in Diecasting Dies
    Journal of Materials Processing Technology, 1995
    Co-Authors: H.y. Lu
    Abstract:

    A understanding of metal flow within the Die Cavity is of particular importance in the control of quality of pressure Diecastings. A computational fluid dynamics technique named SMAC (Simplified Mark and Cell) was adapted and modified to analyze the metal flow pattern during the filling stage of a Die Cavity. The flow pattern and hence the pattern of air-entrapment are found to be sensitive to the Cavity wall thickness. Flow-visualization experiments were carried out to verify the validity of the computer simulation for a rectangular-plate Cavity with either a straight gate or a fan gate. There is a good agreement between the predicted flow and the results from water-analogue experiments.

Weng-sing Hwang - One of the best experts on this subject based on the ideXlab platform.

  • Development of an interactive simulation system for the determination of the pressure-time relationship during the filling in a low pressure casting process
    Science and Technology of Advanced Materials, 2001
    Co-Authors: Jer-haur Kuo, Feng Lin Hsu, Weng-sing Hwang
    Abstract:

    An interactive computer simulation system has been developed in this study to aid the determination of the pressure-time relationship during the filling of a low pressure casting to eliminate filling-related defects while maintaining its productivity. The pressure required to fill a casting in a low pressure casting process can be separated into two stages. The first stage is to exert pressure to force the molten metal to rise in the riser tube up to the gate of the casting Die, which varies from casting to casting due to the drop of the level of the molten metal in the furnace, whilst the second stage is to add an additional pressure to push the molten metal into the Die Cavity in a way that will not cause much turbulence and have the proper filling pattern to avoid the entrapment of gas while maintaining productivity. One of the major efforts in this study is to modify the filling simulation system with the capability to directly predict the occurrence of gas porosity developed earlier to interactively determine the proper gate velocity for each and every part of the casting. The pressure required to fill the Die Cavity can then be obtained from the simulations. The operation principles and the interactive analysis system developed are then tested on an automotive wheel made by the low pressure casting process to demonstrate how the system can aid in determining the proper pressure-time relations, the p-t curve, required to produce a sound casting without sacrificing productivity. © 2001 Elsevier Science Ltd. All rights reserved.

Taylan Altan - One of the best experts on this subject based on the ideXlab platform.

  • Overall review of the tube hydroforming (THF) technology
    Journal of Materials Processing Technology, 2001
    Co-Authors: Muammer Koç, Taylan Altan
    Abstract:

    Tube hydroforming is used to describe the metal forming process whereby tubes are formed into complex shapes with a Die Cavity using internal pressure which is usually obtained by various means such as hydraulic, viscous medium, elastomers, polyurethanes and axial compressive forces simultaneously. Increasing use of hydroforming in automotive applications requires intensive research and development on all aspects of this new technology to satisfy an ever-increasing demand by the industry. A technological review of hydroforming process from its early years to very recent dates on various topics such as material, tribology, equipment, tooling are summarizes.

Qi Hong-yuan - One of the best experts on this subject based on the ideXlab platform.

  • Conformal mapping modeling of metal plastic deformation and Die Cavity in special-shaped extrusion
    2020
    Co-Authors: Qi Hong-yuan
    Abstract:

    With the help of Complex Function Mapping stuDied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension's deformation problems are transferred into two dimension problems, both the stream function and strain ratio field are analyzed in the metal plastic deformation. Using the upper-bound principles, the theory of metal deformation and Die Cavity optimized modeling is established for random special-shaped product extrusion. As a result, this enables the realization of intelligent technique target in the Die Cavity of CAD/CAM integration.

  • VERTICAL CURVE OF Die Cavity AND CONFORMAL MAPPING IN SPECIAL-SHAPED EXTRUSION
    Engineering mechanics, 2020
    Co-Authors: Qi Hong-yuan
    Abstract:

    By Complex Mapping theory, doing mutual numerical calculation to finite odd and even interpolation points on the non-circle cross-section profile of special-shaped products, the conformal mapping function which can mutually transform cross-section region into unit dish region is set up. Translating the extrusion forming of special-shaped products into two-dimension problem, plastic stream function is determined, and the mathematical models of Die Cavity surface with various vertical curves are built up. Using the upper bound method, three types of vertical curves and their optimized parameters of Die Cavity are compared. Taking ellipse-shaped products as examples, their analysis and optimization are carried out.

  • Vertical Curve Analysis of Extruding Die Cavity and Conformal Mapping
    Journal of Rare Earths, 2007
    Co-Authors: Qi Hong-yuan, Chen Keshan, Zhu Heng-jun
    Abstract:

    Abstract With the help of numerical analysis of trigonometric interpolation and Conformal Mapping theory, the conformal mapping function could be set up to translate the non-circle cross-section region of special-shaped products into unit dish region, over numerical finite interpolation points between even and odd. Thus, forming of products extrusion could be turned into two-dimension problem, and plastic stream function could be deduced as well, whilst, mathematical model of Die Cavity surface was determined based on different kinds of vertical curve. By Upper-bound Principle, both vertical curves of Die Cavity and its parameters were optimized. Furthermore, taking ellipse-shaped products as an instance, the calculation and analysis were carried out.

Kwang Yong Choi - One of the best experts on this subject based on the ideXlab platform.

  • A Sheet Metal Forming Simulation of a Fuel Filler Door Considering the Behavior of Air in a Die Cavity
    Steel Research International, 2015
    Co-Authors: Kwang Yong Choi
    Abstract:

    During a sheet metal forming process (especially when outer panels are involved), air trapped between a blank sheet and an upper/lower Die tool can become highly compressed, ultimately influencing blank deformation. To prevent this problem, vent holes are drilled in Die tools based on expert knowledge and experience. This drilling process takes much time and thus can increase lead time. Therefore, the influence of vent holes in sheet metal forming process should be optimized for reducing development costs. CAE can be used to analyze the behavior of air in a Die Cavity during a forming process, incorporating both the elasto-plastic behavior of a blank sheet and the fluid dynamics of air. This study presents a sheet metal forming simulation that simultaneously simulates the behavior of air in a Die Cavity. The Die velocity during the forming process affects the pressure of the trapped air. To include air behavior (based on the ideal gas law and FPM) in an industrial sheet metal forming model, a parametric study is performed for efficiency including reduction of the CPU computational time. The proper technique for reducing the CPU computational time is then applied to a forming simulation of a fuel filler door to correctly understand the process. In this study, the commercial software PAM-STAMP™ and PAM-CRASH™ is used.

  • A sheet metal forming simulation of automotive outer panels considering the behavior of air in Die Cavity
    2013
    Co-Authors: Kwang Yong Choi, Hee Kwan Choi, Chul Ho Kang
    Abstract:

    During a sheet metal forming process of automotive outer panels, the air trapped between a blank sheet and a Die tool can become highly compressed, ultimately influencing the blank deformation and the press force. To prevent this problem, vent holes are drilled into Die tools and needs several tens to hundreds according to the model size. The design and the drilling of vent holes are based on expert's experience and try-out result and thus the process can be one of reasons increasing development cycle. Therefore the study on the size, the number, and the position of vent holes is demanded for reducing development cycle, but there is no simulation technology for analyzing forming defects, making numerical sheet metal forming process simulations that incorporate the fluid dynamics of air. This study presents a sheet metal forming simulation of automotive outer panels (a roof and a body side outer) that simultaneously simulates the behavior of air in a Die Cavity. Through CAE results, the effect of air behav...