Thermal Deformation Analysis of the Rotating Roller in Planar Flow Casting Process
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概要
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In planar flow casting (PFC) process for the manufacture of amorphous ribbon, the thermal deformation of the rotating roller is an important phenomenon that is not only for accuracy controlling the proper nozzle/substrate gap size to obtain the desired ribbon with uniform thickness and excellent quality, but also for stabilizing the manufacture and minimizing its cost. In this paper, by mapping and interpolating 2D temperature results (which are obtained by a conjugated solution of the thermal-fluid dynamics of the melt puddle zone and the heat transfer of rotating roller zone) into a 3D temperature distribution of the roller, the thermal behavior and the roller deformation features of rotating roller at a quasi-steady state and over a initial transient evolution in PFC process are analyzed. The effect of operating parameters and PFC configurations on the thermal and deformation behavior is theoretically examined. Results show that in PCF process, the plastic deformation of the roller occurs in a very thin surface layer under melt puddle, sharply decaying a lower value along the circumferential revolution. The thermal expansion is non-homogeneous on the roller surface and the location of the maximum roller expansion is beyond the coverage of the melt puddle due to the roller revolution. There is a rapid increase of the thermal expansion from the melt contact to ribbon separation. However, for the small melt puddle length, the fluctuation of the expansion along circumferential direction is very small (<10 μm) while the variation of the expansion along ribbon width direction is larger. With the evolution of the time, the thermal expansion rapidly increases at the beginning of the casting process and gradually increases, and the fluctuation of the roller surface expansion increases until a quasi-steady state when the heat balance is reached. The operating parameters and PFC configurations affect the magnitude and profile of roller thermal expansion. It is necessary to pay great attention to the effect of large roller deformation on the small nozzle/roller gap and thin ribbon thickness to avoid some qualities and operating problems in PFC process for the formation of amorphous ribbon.