TAILIEUCHUNG - Heat Transfer Handbook part 127

Heat Transfer Handbook part 127. The Heat Transfer Handbook provides succinct hard data, formulas, and specifications for the critical aspects of heat transfer, offering a reliable, hands-on resource for solving day-to-day issues across a variety of applications. | THERMAL-FLUID EFFECTS IN CONTINUOUS METAL FORMING PROCESSES 1257 40 C 104 F 100 C 212 F 80 C 176 F 70 C 158 F 80 C 2 mm in. Die - 100 C 130 C 266 F 150 C 302 F 175 C 347 F mm in. Wire Direction of drawing 60 C 140 F 50 C 122 F Figure Coupled die and workpiece temperature distributions in wire drawing. From Altanetal. 1983. Figure Coupled die and workpiece temperature distributions in metal extrusion. From Altanetal. 1983. 1258 HEAT TRANSFER IN MANUFACTURING AND MATERIALS PROCESSING A more realistic model of these processes would include several irnporlnnl elements that are ignored in the discrete heat source approach Yang 1992 . These include a Reynolds equation for the pressure distribution in a lubricating film for a gieen film thickness eariation along the die-workpiece interface. Howeeer the film thickness must be determined by the thermoelasto-eiscoplastic deformation behaeior ofthe die and the workpiece. An energy equation for the lubricating film introduces heat generation by eiscous dissipation and pressure work. Local boundary lubricai tion and the associated metalltolmetal shearing ofcontacting asperities still may be present. Temperature and pressure dependence of the density and the viscosity of hlee lubricant must be known as pressures can be exceedingly high in such films. Heat conduction in the deforming solids including heat generation due to plastic deformal tion in the workpiece must be accounted for. Suitable compatibility conditions at the solid-liquid interfaces must be established. Heat losses from the extruded or drawn workpiece after it exits the die must also be accommodated. Figure shows a physical model of the claslohydndlynamic ubrrication phenomenon in wire or strip drawing that is often the basis for a more complete anall ysis. The contact area is dieided into four regions 1 an elastohydrodynamic inlet region 2 a plastohydrodynamic region of srrip df formation 3 a a plaslohydrodynamic outlet region

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