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1

High speed twin roll casting of Al-3Si-0.6Mg strip

100%

Haga T. , Ikawa M. , Watari H. , Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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tom Vol. 17, nr 1-2

337--340

EN

Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast Al-3%Si-0.6%Mg strip was purpose, too. Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed. Findings: Findings are that Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 mm-thick. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not occurred at the outer surface. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminum alloy will becomes easy. The content of Fe in the recycled aluminum alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle. Originality/value: The result means the roll cast Al-3%Si-0.6%Mg has ability to be used as the body sheet of the auto mobile.

2

Clad strip casting by a twin roll caster

100%

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

Archives of Materials Science and Engineering

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2009

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tom 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

Micro-forming of Al-Si foil

100%

Haga T. , Inoue K. , Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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tom Vol. 40, nr 2

115-122

EN

Purpose: of this paper is as below. The investigation of the ability of the cold micro-forming of non-metallic glass was purpose. The grain of the rapidly solidified aluminium alloy became fine. The aluminium alloy foil with fine grain was used, and the investigation of the micro-formability of this alloy was investigated. Moreover, increase of the forming speed was investigated. The increase of the forming speed was purpose of this study, too. Design/methodology/approach: The nozzle pressing melt spinning method was used to attain the rapid solidification of the non-metallic grass. The Al-14mass%Si, which is hyper eutectic but is close to eutectic, was used. The roll contact surface was formed by V-groove. The cold rolling was adopted for forming. The V-groove was machined at the roll surface. The micro-forming was operated at the cold work. Findings: Micro-forming of the crystal aluminium alloy was able by the cold work. The forming speed was 0.04S to form 10 ěm height. The forming speed could be drastically increased. Research limitations/implications: The angle of the V-groove, which was used in the present study, was only 60 degrees. The effect of the groove angle on the protrusion-height was not clear. The used material was only the Al-14mass%Si. Relationship between the material and protrusion-height was not clear. Practical implications: The die for the micro-forming of the resin could be made from economy material by the conventional cold rolling process at short time. Therefore, the mass production of the economy die for resin may be obtained. Originality/value: The micro-forming of the rapidly solidified non-metallic glass by cold work was original.

4

Casting of aluminium alloy strip using an unequal diameter twin roll caster

100%

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

Archives of Materials Science and Engineering

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2008

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tom Vol. 29, nr 2

113-116

EN

Purpose: of this paper is to clear the property and ability of an unequal diameter twin roll caster to cast commercial size strip. Therefore, 400mm-width strip was cast as first step. Surface-condition, microstructure and mechanical property of the strip was investigated. Design/methodology/approach: Method used in the present study was an unequal diameter twin roll caster. This method was devised to realize easy operation of the twin roll casting and increase of casting speed. Findings: are that 400-width-strip of 3084, 5182 and 6022 could be cast at speed of 20 m/min. This strip was about 4 mm-thick. There were some defects on the surface. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the 6022 sheet after T4 heat treatment. Crack did not occurred at the outer surface when strip was bent at width-direction. Research limitations/implications: is that the quantity of the melt was 21kg and investigation of the properties was not enough for practical use. The larger weight of melt must be cast for production. Practical implications: are as below. The 400mm-width strip can be cast easily by the unequal diameter twin roll caster. This caster can be adapted to 3083, 5182 and 6022. Originality/value: as below. The economy sheet with 400mm width can be produced by the unequal diameter twin roll caster. 3083, 5182 and 6022 can be cast at the speed of 20m/min. The thickness of the strip was about 4mm.

5

High speed roll casting of Mg alloy strip by a vertical type twin roll caster

100%

Haga T. , Watari H. , Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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tom Vol. 15, nr 1-2

186--192

EN

Purpose: The possibility of high speed roll casting of AZ31, AM60 and AZ91 was investigated. Warm deep drawing of roll cast magnesium alloy was operated. and formability of roll cast magnesium strip was cleared. Design/methodology/approach: A vertical type high speed twin roll caster was used. The roll casting was operated in the air atmosphere. The casting speed was from 60 m/min up to 180 m/min. Low temperature casting was adopted to realize high speed casting. Findings: Strip thinner 3 mm with 100 width could be cast continuously. The casting ability became better with increasing content of Al. Roll cast Mg alloy strips could be hot-rolled down to 0.5 mm. AZ31 as-cast strip could be thinner down to 0.5 mm only by three times of hot rolling. Deep drawing was operated with three kinds of Mg alloy at 250°C, and LDR value was larger than 2.0. It was shown that deep drawing of AZ91 alloy for casting was possible. Research limitations/implications: There was tendency that cracks occurred at the center in the thickness direction as Al content increased. Practical implications: Sheet metal forming of magnesium alloy with high content Al can be realized. Originality/value: It was shown that possibility of high speed roll casting of magnesium alloy, and warm deep drawing of roll cast AZ91 strip.

6

Grooved roll for a high speed twin roll caster

100%

Haga T. , Hirooka K. , Watari H. , Kumai S.

Archives of Materials Science and Engineering

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2008

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tom Vol. 30, nr 2

117-120

EN

Purpose: Purpose of this paper is investigation of the effect of roll-surface on the strip-surface. Improvement of small cracks on the strip-surface was tried and effect of groove at the roll surface on the strip surface was shown. Design/methodology/approach: Method used in the present study was high speed twin roll caster with grooved roll. Two kinds of grooves were used: one was parallel groove and the other was cross groove machined by knurling and bite attached to a lathe. Findings: Findings of this research are that grooved roll was effective to eliminate the small cracks on the strip surface. The contact condition between the roll and the melt became uniform by the small groove on the roll surface. Contact area became small, and heat transfer between the melt and roll became small, too. As the result, chill structure did not become columnar, and crack did not occur. Groove pattern on the strip surface could be erased by the cold rolling. Research limitations/implications: Research limitation is that groove life could not be investigated. Practical implications: Practical implications are as below. The roll load was small and strip was not hot-rolled in a high speed twin roll caster. The grooved roll made strip-surface sound. Grooved 600mm width roll was tested, and usefulness of the grooved roll was shown. Originality/value: In the present study effect of the grooved roll on a high speed twin roll caster was investigated.

7

High speed twin roll casting of 6016 strip

100%

Haga T. , Ikawa M. , Watari H. , Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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tom Vol. 18, nr 1-2

371--374

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of thin aluminum alloy strip. 6016 aluminum alloy is used for sheet metal of the automobile. Therefore, casting of 6016 was tried in this study. Castability and characteristics of roll cast 6016 strip 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. The 6016 could be cast at speed of 60 m/min. The thickness of the 6016 was 3 mm. The microstructure at as-cast and after T6 heat treatment was shown. The microstructure was very fine by the effect of the rapid solidification. The mechanical properties were investigated by the tension test and 180 degrees bending test. The as-cast strip could be cold rolled down to 1 mm without homogenization. The result of tension test (gage length 50mm) of T4 strip was as below, tensile stress was 242 MPa, proof stress was 123 MPa and elongation was 26%. There was no crack at the outer surface of 180-degree-bent strip until contact. This shows the strip endure the hem forming. Research limitations/implications: is the width of the strip was 100 mm. The test using a large scale twin roll caster must be operated. Practical implications: are as below. The mechanical properties of the roll-cast 6016 were enough for the sheet metal for the automobile. The low productivity of the twin roll caster could be improved, and economy 6016 strip was able to produce. Originality/value: is that 6016 strip could be cast at speed 60 m/min and this strip had good mechanical properties.

8

High speed twin roll casting of 6016 aluminium alloy strip

100%

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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tom 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.

9

High speed twin roll casting of recycled Al-3Si-0.6Mg strip

100%

Haga T. , Ikawa M. , Watari H. , Kumai S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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tom Vol. 21, nr 1

7-12

EN

Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of recycled Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast recycled Al-3%Si-0.6%Mg strip was purpose, too. Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed. Findings: Findings are that recycled Al-3%Si-0.6%Mg was could be cast at speed of 60 m/min. This strip was 3.1 mm-thick. As cast strip could be cold-rolled down to sheet of 1 mm-thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not occured at the outer surface. This result means the roll cast recycled Al-3%Si-0.6%Mg can be used as the body of the auto mobile. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties was not enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Practical implications: Practical implications are as below. The economy sheet for the auto mobile can be produced by the high speed twin roll caster. Al-3%Si-0.6%Mg can be used both the casting and plastic forming. Therefore, fractionation in the recycle of the aluminium alloy will becomes easy. The content of Fe in the recycled aluminium alloy increases. Fe becomes intermetallic of AlSiFe. Si for Mg2Si becomes deficient. 3%Si was enough for Mg2Si if AlSiFe was precipitated. Al-3%Si-0.6%Mg is suitable for recycle. Originality/value: The economy sheet of Al-3%Si-0.6%Mg can be made by the high productivity of the HSTRC. The result of this report contributes to make the economy aluminium alloy sheet for the automobile.

10

A vertical type twin roll caster for an aluminium alloy clad strip

100%

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

Archives of Materials Science and Engineering

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2013

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tom Vol. 62, nr 1

36--44

EN

Purpose: of this paper: Twin roll casters that can cast two layers and three layers clad strip of aluminium alloys were invented. One of the purposes of this paper is to report that the two layers and three layers clad strip could be cast by the twin roll caster of this study. The investigation of the characters of these casters and the clad strips was purpose of this paper, too. The connecting at the interface between the strips was most important in the casting of the clad strip. Therefore, the attention was paid on the conditions of the interface. Design/methodology/approach: A vertical type tandem twin roll caster and a twin roll caster equipped with a scraper were designed, assembled and tested. Castings of the two layers clad strip and the three layers clad strip directly from molten metal were tried using these twin roll casters. The connecting strength between strips was investigated by the continuous bending test and the cold rolling. The diffusion and re-melting at the interface was investigated by the SEM-EPMA. Findings: The twin roll casters invented in this study could cast the two layers and three layers clad strips directly from molten metal. These clad strips had clear interface between the strips. This means that the mixing of the two alloys did not occur at the interface. The diffusion of elements of the each strip into another strip did not occur at the interface. The connecting strength was enough to endure the peeling at the interface by continuous bending. The clad ratio could be controlled by the solidification length up to 10:1. Two layers clad strip assembled from Al-Mg alloy strip and another aluminium alloy strip could be cast without defect by the effect of the scraper. The three layers clad strip which base strip had lower melting point than that of the overlay strip could be cast. Practical implications: The three layers clad strip, which base strip is 3003 aluminium alloy and overlay strips are 4045 aluminium alloy, can be used for the brazing sheet of the radiator of the automobile. The twin roll caster of this paper could cast this type of clad strip. The process saving and the energy saving can be attain by the twin roll caster of this paper. The clad ratio between the base strip and the overlay strip was smaller than 10:1. Originality/value: The twin roll casters that could cast two and three layers clad strips were original invention. using the twin roll caster.

11

High speed twin roll casting of 6061 alloy strips

100%

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

Archives of Materials Science and Engineering

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2008

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tom Vol. 31, nr 1

49-52

EN

Purpose: of this paper is to clear the possibility of high speed roll casting of thin strips of two aluminum alloys: 6061 and recycled 6061. Mechanical properties of the roll cast 6061 and recycled 6061 strips were investigated in the frame of this purpose. Design/methodology/approach: Methods used in the present study were high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification and increase the casting speed. Findings: are that 6061 and recycled 6061 could be cast at speed of 60 m/min. Casted strips were about 3 mm thick. As cast strip could be cold-rolled down to sheet of 1 mm thick. 180 degrees bending test was operated on the sheet after T4 heat treatment and crack was not worse than 6022 which is typical aluminum alloy for sheet of the automobile. This result means the roll cast 6061 can be used as a sheet for body of the automobile instead of 6022. Research limitations/implications: Research limitation is that the width of the strip was 100 mm and investigation of the properties were enough for practical use. Wider strip must be cast using the twin roll caster of the size for production. Originality/value: The economy sheet of the 6061 for the auto mobile can be produced by the high speed twin roll caster. 6061 is typical wrought aluminum alloy of 6000 series. Therefore, the sheet of 6061 will become economy. 6061 can be recycled at two times when the 6061 is cast into strip by the high speed roll casting.

12

Strip casting using a single roll caster equipped with a scraper

88%

Haga T. , Akitsu K. , Kamakura K. , Kumai S. , Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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tom Vol. 55, nr 1

26--32

EN

Purpose: Purpose of this paper is to investigate the ability of a single roll caster equipped with a scraper. The purpose of the development of the single roll caster equipped with a scraper is casting of the strip without centre line segregation and porosity and with sound free solidified surface. The single roll caster can cast the strip without the centre segregation and porosity. However, the conditions of the free solidified surface and the thickness distribution are not sound. The scraper was adopted in order to improve the free solidified surface. Investigation of the effect of the scraper and the properties of the roll cast strip is the purpose of this paper. Design/methodology/approach: A scraper was developed to improve the free solidified surface condition. The scraper scribed the semisolid metal on the free solidified surface to make the free solidified surface flat. The scraper was made from mild-steel-plate, and it was coated by the insulator sheet of 2 mm-thick. The scraper was pushed to free solidified surface by the constant load. Findings: The scraper was very useful to improve the free solidified surface. AA5182 aluminium alloy strip could be cast at the speed up to 40 m/min. There was no centre segregation and porosity. There was no difference between the roll contact surface and the scribed surface. The mechanical properties of the roll cast strip were as same as those of strip made from D.C. cast slab. Hi-content Al-Mg alloy like Al-10 mass%Mg, which cannot be cast into the strip by the twin roll caster without centre segregation, could be cast into the strip without defect. Research limitations/implications: Metal which was investigated was only aluminium alloy. It is not clear that this process is useful to other alloys like steel, copper et. al. Practical implications: This process may be able to be used instead of the D.C. casting and the twin roll casting. Especially, this caster is useful the strip casting of the Al-Mg alloy. Originality/value: The single roll caster equipped with a scraper is original development. This caster may be useful for aluminium and magnesium sheet making companies.

13

Twin roll casting of magnesium alloys with high aluminum contents

88%

Watari H. , Haga T. , Shibue Y. , Davey K. , Koga N.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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tom Vol. 18, nr 1-2

419--422

EN

Purpose: The purpose of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-quality magnesium sheet alloys with high aluminum contents, such as AZ61 and AZ91. The aim of the work is to establish a twin roll casting technology to facilitate the manufacture of AZ61 and AZ91 magnesium sheet alloys economically whilst maintaining high quality. Design/methodology/approach: A horizontal type twin roll caster was used to manufacture thin magnesium alloy sheets of AZ61 and AZ91. Pair of copper alloy roll and pure copper roll was used for the horizontal type twin roll caster. A closed type tundish was set to the roll caster to keep stable contact of molten magnesium with upper and lower rolls. Findings: The experiment results clarified that AZ61 and AZ91 sheets can be manufactured by twin roll casting process. The product sheet thickness in the present experiment is 2.0 to 4.5 mm for AZ91, 2.5 to 5.0mm for AZ61. Mill stiffness and a method of predicting the cast sheet’s thickness were investigated to determine the appropriate manufacturing conditions. The microstructure of AZ61 cast strips was equiaxed structure and the crystal sizes are different depending on cross section observed. The dendric and equiaxed microstructure were seen in the microstructure of AZ91 cross section. The intermetllic Mg17Al12 was seen in the grain boundary in AZ91 when roll speed was very slow. The grain size of the manufactured wrought magnesium alloys sheet was less than 10 micrometers. The obtained magnesium alloy sheet exhibited an equivalent limiting drawing ratio in a warm-drawing test. The limiting drawing ratio of AZ61 was 2.6 and 2.4 for AZ91. Research limitations/implications: The suitable roll speed was from 9m/min to 15m/min in manufacturing AZ91 and AZ61 strip using copper alloy rolls. When in use of pure copper roll, strips were cast between 6m/min and 20m/min for manufacturing AZ61 and AZ91. The superheats in the experiment were 15ºC and 30ºC. The cast strips should be hot rolled at 300ºC. Originality/value: value In this experiment, it is clarified that AZ61, AZ91 sheets can be manufactured by twin roll casting. These cast sheet can be hot rolled and the manufacturing process by twin roll casting enable to manufacure thin magnesium sheet alloys with high aluminum contents. It has been found that the manufactured cast AZ61 and AZ91 have good formability by a warm deep drawing test.

14

Roll caster for the three-layer clad-strip

88%

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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tom 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.

15

Analytical and experimental study on lateral extrusion of cross fittings with a lost core

88%

Ohashi T. , Ito H. , Shinozaki K. , Ito S. , Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

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tom Vol. 18, nr 1-2

399--402

EN

Purpose: The authors discuss deform mechanism of lateral extrusion process with a lost core for cross fittings. Outline of the is as follows: At first, cavity of pipe, or channel material, is filled up by liquid of low temperaturę melting material, for instances, low temperature melting alloy, ice (or water) and wax. Then low temperature melting material is solidified to be a soluble core of pipe. Authors call this soluble core the ‘lost core [1-4].’ The third, the material is compressed longitudinally as a composite billet, and extruded for lateral direction. After deformation, low temperature melting material is melted and removed. The authors think the process is suitable for production of cross-fittings because such the product has constant sections for lateral direction. Design/methodology/approach: The authors have examined the process with experiments [1] and numerical analysis with ANSYS9.0. Findings: The feature of the process is revealed. Extrusion defect is caused at the center of the cross on the inner wall of the pipe because of volume constancy when the branch diameter close to the initial pipe diameter. In such the case, contact between pipe and die surface is unstable and the branch part is not stretched enough, then it causes wrinkles. In such the case, it is better to provide more pressure against the head of branch projection. Research limitations/implications: In future work, the effect of the relationship amongst mechanical properties of the pipe and lost core is to be examined. In addition, the authors will seek better material for the lost core that is cheaper, easier to remove, clean and safer for the man and environment. Practical implications: Throughout the above research, authors conclude the suggested process is useful for making cross fittings, and the process can be useful on the other hollow products. Originality/value: The above result helps design of the economical process for fittings. The process requires only simple equipments.

16

Effects of production parameters on characteristics of magnesium alloy sheets manufactured by twin-roll casting

88%

Watari H. , Haga T. , Davey K. , Koga N. , Yamazaki T.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

tom Vol. 16, nr 1-2

171--176

EN

Purpose: The purpose of the work is to establish a manufacturing process and technology to facilitate the economical manufacture of high-quality magnesium sheet alloys. Design/methodology/approach: Magnesium alloy AZ31B was used to investigate the appropriate manufacturing conditions for use in twin-roll strip casting. Temperatures of the molten materials and roll speeds were varied to find the appropriate manufacturing conditions. The effects of manufacturing conditions on possible forming were clarified in terms of roll speeds and roll gaps between upper and lower rolls. Findings: In the hot-rolling process, a temperature exceeding 200°C was chosen to keep cast products from cracking. An appropriate annealing temperature was effective for homogenizing the microstructure of the rolled cast sheets after the strip casting process. The grain size of the manufactured wrought magnesium alloys sheet was less than 10 micrometers. The obtained magnesium alloy sheet exhibited an equivalent limiting drawing ratio in a warm-drawing test. Research limitations/implications: AZ31 were used to investigate the appropriate manufacturing conditions for use in twin-roll strip casting. Casting temperatures were varied from 630°C to 670°C to find the best casting conditions. Roll casting speeds were varied from 5m/min to 30 m/min in order to examine which roll speed was appropriate for solidifying the molten magnesium. Practical implications: It was found that the cast magnesium sheet manufactured by roll strip casting could be used for plastic forming if the appropriate magnesium sheets were produced after the roll casting process. Originality/value: This paper showed the effectiveness of twin roll casting for magnesium alloys by a horizontal roll caster.

17

Aluminum alloy semisolid strip casting using an unequal diameter twin roll caster

88%

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

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

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tom Vol. 14, nr 1-2

157--162

EN

Purpose: A Purpose of the present study was to break through the disadvantage of the twin roll caster for aluminum alloy. They were slow casting speed and limitation of alloy. For example, the casting speed was slower than 5 m/min, and casting of hypereutectic Al-Si alloy was difficult. In order to break through the disadvantages, semisolid casting using an unequal diameter twin roll caster was tested its ability. Design/methodology/approach: The specification of the unequal diameter twin roll caster is as below. The diameter of the upper roll was 250 mm, and that of the lower roll was 1000 mm. The width of the roll was 100 mm. The semisolid slurry was made by a cooling slope. Findings: The microstructure of the strip became very fine. Especially, primary and eutectic Si became very fine. This was the effect of rapid solidification. As the result, the ductility of Al-16%Si was improved. Research limitations/implications: 6111 aluminum alloy strip was cast at speeds of 5, 10 and 20 m/min. This caster could cast the strip at the speeds higher than the conventional twin roll caster. Start of casting was very easy. The hypereutectic Al-16%Si alloy, which has wide freezing zone, could be cast in to the strip by the unequal diameter twin roll caster. This was the effect of the cooling of the strip on the lower roll. Originality/value: The roll cast Al-16mass%Si strip had good ductility, and could be cold rolled. Annealed 0.5 mm thick Al-16mass%Si could be bent at radius of 0.75mm.

18

High speed twin roll caster for aluminum alloy thin strip

88%

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

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

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tom 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.

19

Lateral extrusion of a cross fitting with a lost core

88%

Ohashi T. , Ito H. , Shinozaki K. , Ito S. , Watari H.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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tom Vol. 24, nr 1

413-420

EN

Purpose: Lateral extrusion process with a lost core for cross fittings is suggested. At first, cavity of tube is filled up by low temperature melting alloy. Then low temperature melting material is solidified to be the "lost core". The third, the material is extruded for lateral direction to be a cross-fittings. After deformation, low temperature melting alloy is melted and removed. The authors discuss its deform mechanism in this paper. Design/methodology/approach: Experiments and numerical analysis with ANSYS9.0. Findings: Extrusion defect is caused at the center of the cross on the inner wall of the pipe because of volume constancy when the branch diameter close to the initial pipe diameter. In such the case, contact between pipe and die surface is unstable and the branch part is not stretched enough, then it causes wrinkles. In such the case, it is better to provide more pressure against the head of branch projection. Research limitations/implications: The effect of the relationship amongst mechanical properties of the pipe and lost core is to be examined in future. We must seek better material for the lost core that is cheaper, easier to remove, clean and safer for the man and environment. Practical implications: This methodology is suitable for production of the hollow products having constant sections for lateral direction. Originality/value: The above result helps the economical production of hollow products with simple equipments.

20

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

75%

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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tom 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.