| Research Abstract |
Although studies on applying an ultrasonic oscillation (USO) to materials have been partly carried out in such fields of cutting, blanking, drawing and so, there have been few cases of utilizing the USO to sheet rolling. In our study, an exciting rolling method, which utilizes the ultrasonic waves, has been developed for materials to be rolled such as SUS304, SUS430, Ti, Al, Cu, ultra low carbon steel (ULCS) and 80kg high tensile strength steel (HT80), and thereby the variations of both load characteristics and material surface characteristics have been clarified.
1.Characteristics of 2-high mill roll/dry cold rolling, where the USO being applied to sheet materials :
(1) The load decrement effect was confirmed in such materials as SUS304, SUS430, Ti, Al and HT80. The tendency of its effect became more and more conspicuous with increasing a draft. (2)In cases of rolling Cu and ULCS, none of the load decrement effect was observed. (3)As for a magnitude of the load decrement effect due to a
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change of conditions, in case of rolling SUS304, a thicker sheet had a bigger effect and a lower rolling speed caused a greater load decrements
Characteristics of 2-high mill roll/lubricated cold rolling :
The load decrement due to lubrication itself was the main factor, and any multiplier effects due to the USO rolling were not observed.
Result of material surface analysis :
None of differences were observed both in the microstructures of the surface layer section and in the hardness distributions in the sheet thickness direction before and after the USO rolling. Changes of the surface roughness, brightness and irregularity according to various conditions, were comprehensible, but any constant tendency was not confirmed.
2.Characteristics of 2-high mill roll/dry cold rolling, where the USO being applied to the work roll :
In case of rolling ULCS, a same level of the load increment as shown when the USO was applied to the sheet material to be rolled, was observed. The roll surface roughness had been greatly changed, and therefore further study on the equipment including any damages to it should be required.
3.Measuring of sheet amplitude :
According to the results of measuring the sheet materials to be rolled before rolling, with a laser displacement transducer, when the amplitude being set at 3.3 μm, both the frequencies and the amplitudes were higher in cases of rolling Al, Cu and ULCS, medium in case of SUS, and lower in cases of Ti and HT80. The difference in such a tendency seems to depend greatly on a soft or hard material. Less
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