Wyniki wyszukiwania - Biblioteka Nauki

1

Lateral extrusion of tailor welded aluminum alloy pipes with a lost core of low temperature melting alloy

100%

Ohashi T. , Liu G.

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2009

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tom Vol. 32, nr 1

61-65

EN

Purpose: In this paper, the authors employ tailor welded aluminum alloy pipes for lateral extrusion process with a lost core to perform a hollow light-weight-part. Design/methodology/approach: The pipe is welded longitudinally by YAG-laser. “The lateral extrusion process with a lost core (LELC)” consists of lateral extrusion of pipes with a soluble solid core, called the “lost core”, which serves as a plastic mandrel. The process proceeds as follows. First, the pipe cavity is filled with the liquid low temperature melting material composing the lost core. The liquid is then solidified to form the soluble core of the pipe. The material is compressed longitudinally as a composite billet as well as forging, and extruded in the lateral direction. After the pipe is deformed, the lost core is melted and removed. s. The bulge by the LELC is carried out by extruding the material for the lateral direction, however the simple bulge by hydro-forming is done by internal pressure. Findings: The LELC process can make a hollow product having uneven wall thickness without the deformation concentrating on a thinner part of the material, because the circumferential deformation of the material will be performed by its meridian strain. Practical implications: The authors have developed LELC process in which the lost core consists of low-temperature melting alloys and have tried to apply the process to perform bulge process with a tailor-welded pipe having two different wall thickness. Originality/value: Optimum volume distribution is important for light-weight-parts, and employment of tailor-welded blanks is effective technique in sheet metal forming. Combination of employment of hollow shape and tailor-welded blanks seems to be hopeful.

2

Employment of alumina suspension pad for v-bending of SUS304 strip

80%

Ohashi T. , Chiba H. , Takano H.

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2008

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tom Vol. 30, nr 1

57-60

EN

Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an application on v-bending of thin stainless steel strips in this paper. Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluid for forming. The authors evaluated the suspension with backward extrusion test. Followed by SUS304 stainless strip with 0.25mm thickness and 30mm width on the pad of the suspension with a v-bend punch. Findings: Behaviour of the suspension is revealed in the backward extrusion test. Migration of water takes important role in it. In v-bending test, including acute angle bending, the authors bend the strip with only the vbend punch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that forming load is less than with general polyurethane tools. Research limitations/implications: Spring-back in partial bending, which is similar to the suggested process, is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, the authors will evaluate the spring-back in the suggested process in further study. Practical implications: Polyurethane pad is used in bending process generally because of advantageous points in easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessity of large forming load. The alumina concentrated hard-sphere suspension can be employed for such a pad with unlimited life. In addition, such dilatant fluid can be applied on other metal forming process as easy tool. Originality/value: Employing dilatant fluid for forming tools is new idea. V-bending with an alumina concentrated hard-sphere suspension was attempted.

3

Employment of concentrated-hardsphere-suspension pad for V-bending of thin strip

80%

Ohashi T. , Chiba H. , Takano H.

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2008

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tom Vol. 31, nr 2

699-704

EN

Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an application on v-bending of thin stainless steel strips in this paper. Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluid for forming. The authors evaluate the suspension with backward extrusion test. Then, the authors try to bend SUS304 stainless strip with 0.25 mm thickness and 30 mm width on the pad of the suspension with a v-bend punch. Findings: Behaviour of the suspension is revealed in backward extrusion test. Migration of water takes important role in it. In v-bending test, including acute angle bending, the authors bend the strip with only the v-bend punch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that forming load is less than with general polyurethane tools. Research limitations/implications: Spring-back in partial bending, which is similar to the suggested process, is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, the authors are going to evaluate the spring-back in the suggested process in further study. Practical implications: Polyurethane pad is used in bending process generally because of advantageous points in easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessity of large forming load. The alumina concentrated hard-sphere suspension can be employed for such the pad with unlimited life. In addition, such the dilatant fluid can be applied on other metal forming process as easy tool. Originality/value: Employing dilatant fluid for forming tools is new idea. Authors try v-bending with an alumina concentrated hard-sphere suspension.

4

Lateral extrusion of a cross fitting with a lost core

71%

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

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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.