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1

Roll caster for the three-layer clad-strip

Nakamura R., Yamabayashi T., Haga T., Kumai S., Watari H.

Archives of Materials Science and Engineering

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2010

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Vol. 41, nr 2

112-120

EN

Purpose: of this paper is to show the characteristics of two kinds of roll casters for three-layer clad strip of aluminium alloys. Moreover, the characteristics of these twin roll casters were compeered with the early type of roll casters for clad strip. Design/methodology/approach: Design was tried to attain the fabrication of the roll casters to cast the three-layers-clad-strip. One caster was an unequal diameter roll caster equipped with a scraper. The scraper was adopted to prevent the mixture of different kinds of melts of the alloys. The scraper was used to cast the clad strip with clear interfaces between each strip. The other caster was a tandem type roll caster assembled from two vertical type twin roll casters. A vertical type of twin roll was mounted on the other vertical type of a twin roll caster. Findings: Three layers of clad strips could be cast by two kinds of the roll casters developed in the present study. The casting speed was 20 m/min. This speed was much higher at the conventional twin roll caster for the aluminium alloys. Each strip of three layers clad strip was connected strictly. The element of clad strip did not peel at the interface by continuous bending. The as-cast clad strip could be cold-rolled. The element of alloys did not mix at the connecting interface of the strips. The casting conditions which affected the connecting of the strips and condition of interface were investigated and shown in this paper. Research limitations/implications: The width of the strip was from 30 mm to 50 mm. The casting of the wide strip was not investigated. The alloy used in the present study was only aluminium alloys. The length of the cast strip was 3 m. The thickness of element strip was from 0.8 mm to 1.5 mm. The difference of the melting temperature of the alloys was within 50°C. The number of the layers was less than three layers. Practical implications: The roll caster invented in the present study can be used for the fabrication of the clad strip. The clad strip is, for example, used for the brazing sheet of the radiator for the automotive industry. Originality/value: There was not a report concerning the roll caster for three layers clad strip. The roll casters for clad strips shown in this paper were of an original process. Especially, the use of the scraper in the roll casting was original.

2

Clad strip casting by a twin roll caster

Haga T., Nakamura R., Kumai S., Watari H.

Archives of Materials Science and Engineering

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2009

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Vol. 37, nr 2

117-124

EN

Purpose: Of this paper is to realize the casting of the clad strip by only one process. Therefore, the investigation of the ability of the casting of the clad strip by a vertical type twin roll caster was operated. The aim of the use of the twin roll caster to make clad strip was in the reduction of the production-energy of the clad strip. Design/methodology/approach: Used in the present study was a vertical type twin roll caster with the scriber. The scriber was used to prevent the mixture of the two kinds of the melts. The scriber was set at roll-bite, and the scriber contacted to the one of solidification layer. The melt was stopped by the scriber and the only the solidification layer was dragged by the roll. Findings: The clad strip with the clear interface could be by the vertical type twin roll caster with the scriber. The scriber was useful to drag only the solid and semisolid layer. The two kinds of strips were connected strictly at the interface of the clad strip. The clad strip was not broken at the interface by the continuous bending. Research limitations/implications: Are that 100 mm width-strip was cast in the present study. Ability of the clad strip that is wider than 100 mm was not clear. The control of the clad ratio was not investigated. Practical implications: The twin roll caster devised and investigated in this report is useful to cast clad strip like the brazing sheet for the radiator of the automobile. Originality/value: The vertical type twin roll cater to cast clad strip is original process. The scriber was used to prevent the mixture of the two kinds of melts. The scriber was not used in the previous research to cast clad strip at the twin roll caster, and use of the scriber was the first try.

3

High speed twin roll casting of 6016 aluminium alloy strip

Sakaguchi H., Haga T., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

495-498

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of aluminium alloy strip. In the body of the automobiles, a sheet of 6016 aluminium alloy is adopted for the outer panel. Therefore, casting of 6016 was tried in this study. Characteristics of roll cast 6016 were investigated. Design/methodology/approach: was a high speed twin roll caster. The high speed twin roll caster was designed to overcome the low castability of the twin roll caster. Findings: are as below. 6016 alloy could be cast into the strip continuously at the speed of 60 m/min. The thickness of the strip was 3.4 mm. The microstructure at as-cast and after T4 heat treatment was shown. The microstructure was very fine. The mechanical properties were investigated by the tensile test and 180 degrees vending test. The as-cast strip could be cold rolled without homogenization to 1 mm. Result of tensile test was tensile strength was 230MPa, 0.2% proof stress was 118MPa and elongation was 33%. 6016 strip of T4 heat treatment could be bent 180 degrees without occurrence of crack at the outer surface or breaking. Research limitations/implications: is the width of the strip was 100 mm. It is necesarry to test twin roll caster equipped wide rolls. Practical implications: are as below. The mechanical properites of the roll-cast 6016 were enough for the sheet metal for the automobile. The low productivity of the twin roller caster could be improved. Originality/value: is that 6016 strip could be cast continuously at speed 60 m/min and this strip had good mechanical properties.

4

High speed twin roll caster for aluminum alloy thin strip

Haga T., Inui H., Sakaguchi H., Watari H., Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

365-371

EN

Purpose: In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated. Design/methodology/approach: The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metallography, a tension test, and a bending test. Findings: A vertical type twin roll caster for strip casting of aluminum alloys was devised. The strip, which was thinner than 3 mm, could be cast at speeds higher than 60 m/min. Features of the twin roll casters are as below. Copper rolls were used and lubricant was not used in order to increase the casting speed. A casting nozzle was used to set the solidification length precisely. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Separating force was very small in order to prevent sticking of the strip to the roll. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed and high-cooling rate twin roll caster of the present study for recycling aluminum alloy was investigated. Fe was added as impurity to 6063 and A356. The roll caster of the present study was useful to decrease the influence of impurity of Fe. Research limitations/implications: A high-speed twin roll caster of vertical type was designed and assembled to cast aluminum alloy thin strip. Originality/value: The results demonstrate that the high-speed twin roll caster can improve the deterioration by impurities.

5

Development of manufacturing process of wrought magnesium alloy sheets by twin roll casting

Watari H., Paisarn R., Haga T., Noda K., Davey K., Koga N.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

515-518

EN

Purpose: The purpose of the work is to development of a strip casting technology for manufacturing magnesium alloy sheets. The aim of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-strength magnesium sheet alloys. Design/methodology/approach: A horizontal type twin roll caster was used to manufacture magnesium alloy sheets. Pair of copper alloy roll, pure copper roll and steel roll was used for the horizontal type twin roll caster. The diameter of the rolls was 300 mm and the width of rolls was 100 and 150 mm. Findings: The magnesium alloy sheets could be successfuly manufactured by the horizontal twin roll caster. The product sheet thickness in the present experiment was 2.0 to 5.0 mm. The equiaxed microstructure was observed in cast magnesium alloys when a pair of copper and copper alloy rolls were used. The mean grain size of the cast magnesium alloys strip was from 30 to 60 micrometers. After hot rolling process, the grain size was reduced to about 10 micrometers. The obtained magnesium alloy sheet indicated a good plastic formability by a warm-drawing test. Research limitations/implications: The superheat in the experiment was between 15 and 30 degrees centigrade, also an appropriate hot rolling temperature was 250 degrees centigrade for AZ31, AZ61 and AM60, 300 degrees centigrade for AZ91. Practical implications: The proposed manufacturing process was effective from the view point of economical manufacturing process as well as of formation of rapid solidification microstructures. Introducing the twin roll casting technology enable to manufacture magnesium sheet alloys with high aluminium contents, such as AZ61, AM60 and AZ91. Originality/value: AZ31, AM60, AZ61 and AZ91 wrought magnesium alloy sheets can be manufactured economically by twin roll casting. These cast sheet can be hot rolled and the proposed manufacturing process enables manufacturer to manufacture thin magnesium alloy sheets with high aluminium contents such as AM60, AZ61 and AZ91.