• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.170-173
• /
• 2001

The design for cold extrusion dies is very important because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, two assumptions were proposed. First assumption was selected by yielding strength dependent on the to hoop stress of each ring in dies. Second assumption is that the maximum inner pressure is determined when yielding occurs in one ring of dies. To obtain the maximum inner pressure the flexible tolerance method was applied. A comparison of design values between the proposed method and the conventional method has been discussed.

• Transactions of Materials Processing
• /
• v.12 no.2
• /
• pp.116-122
• /
• 2003

In the Prestressed die design for cold working, many constraining conditions should be considered to insure the die safety and to improve the dimension accountancy products. Among the constraining conditions, yielding conditions, diameter ratios and interferences between rings are very important. . In this paper, therefore, flexible tolerance method was used in order to search the optimum values of design variables. The maximum inner pressure is used as objective function in this numerical analysis. In the design Process, it was also involved the safety factor to the yield strength of each ring by considering the allowable tensile or compressive hoop stress in each ring. The proposed technique has been applied to the die design of backward extrusion process, and it's analytical results have been compared with that of the conventional design method.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.1
• /
• pp.167-174
• /
• 2005

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.7
• /
• pp.153-162
• /
• 2004

This paper describes a research work on the die design for the deep drawing ＆ ironing(D.D.I.) of high pressure gas cylinder. D.D.I die set is large-sized die used in horizontal press, which is usually composed of drawing, and ironing die. Design method of D.D.I. die set is very different from those of conventional cold forging die set.. Out diameter of the die set is fixed because of press specification and out diameter of the insert should be as small as possible for saving cost of material. In this study, D.D.I die set has been designed to consider those characteristics and the feasibility of the designed die has been verified by FE-analysis. In addition, the automated system of die design has been developed in AutoCAD R14 by formulating the applied methods to the regular rules.