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Preliminary Study on the Technology of Metal Hot Extrusion Without Discard

Author: WangTianShi
Tutor: ZhangRenZuo
School: Tsinghua University
Course: Materials Science and Engineering
Keywords: extrusion without discard hot extrusion compressed NaCl-powder constitutive equation
CLC: TG376.2
Type: Master's thesis
Year: 2009
Downloads: 15
Quote: 0
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Abstract


Extrusion is more competitive than conventional processing in metal forming. Nevertheless, the discard of blank left by extrusion metal reduces production efficiency. In addition, metal discards treated as scraps are the waste of production cost. Thereby, the research on a technology of metal hot extrusion without discard is beneficial to increase production efficiency and save cost of extrusion production operation.The technology of metal hot extrusion without discard mainly includes two parts, i.e. the forming properties of discard block and the actualization of extrusion without discard. The first part requires the research on material, forming methods, mechanical properties and deformation of discard block. The second part needs the research on design and manufacture of tool and die, working procedure of extrusion and analysis of forming results.The NaCl discard block was prepared using the method of mold press forming by NaCl powder under pressure 400MPa. The creep tests using varied temperature and strain rate have been performed on compressed NaCl-powder under high temperature and pressure. The undetermined constants n, Q and A of creep constitutive model for compressed NaCl-powder were obtained by using power-law creep theory. The hot extrusion deformation of NaCl discard block was simulated by using finite element software Deform-2D.A set of tool and die was designed and manufactured considering the features of aluminum hot extrusion and experiment conditions. Besides, the strength checking and temperature checking for tools have been performed. In order to understand deformation properties of NaCl discard block, the forming characters of hot extrusion of NaCl bar using varied extrusion ratio, temperature and height of NaCl blank have been studied. The forming performance of aluminum hot extrusion without discard technology was studied under varied extrusion ratio, temperature and ratio of aluminum/salt. Compared with traditional extrusion, the extrusion pressure of extrusion without discard technology was low, about 53%~82% of traditional extrusion pressure; the discards left by extrusion without discard technology were very thin (0.3mm), about 12%~32% of traditional extrusion discards.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metal pressure processing > Extrusion > Extrusion process > Hot extrusion
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