COMPOSITE TUBE FOR REFRIGERANT PASSAGE OF ALUMINUM ALLOY AND ITS MANUFACTURE

Japanese Patent JPH1144497

A

PROBLEM TO BE SOLVED: To reduce the generation of blow holes in an interface between an inner tube and an outer tube and prevent the separation or the like of the inner tube by a method wherein the thickness of a two-layered composite tube or a three-layered composite tube, made by fitting forcibly a tubular aluminum alloy inside material into a tubular aluminum alloy core material, is reduced to a size not more than a given value by applying extrusion work and the like. SOLUTION: In the manufacture of a composite tube for the refrigerant passage of an aluminum alloy heat exchanger, a tubular aluminum alloy inside material hollow billet 2 is fitted forcibly into a tubular aluminum alloy core material hollow billet 1 to make a two-layered composite hollow billet. Further, the two-layered composite hollow billet is fitted forcibly into an aluminum alloy outside hollow billet to make a three-layered composite hollow billet. Hot extrusion is applied on the composite hollow billet or drawing work is applied after the hot extrusion. A hollow billet, coming to the outside upon effecting force fitting, is preferable to be heated to the temperature of 350-600 deg.C and, in this case, the force fitting allowance is preferably to be 0.4 mm or more and an inserting allowance is preferably to be 0.8 mm or more. Further, the thickness of an obtained composite tube is preferably to be 0.8 mm or less.

YOSHIDA AKINORI
KONDO YOSHINORI
KATO SEIICHI
YAMAMOTO TETSUYA
SHINPO TANEHARU

JP21261397A

February 16, 1999

July 23, 1997

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FURUKAWA ELECTRIC CO LTD
DENSO CORP

B21C23/00; B21C23/22; B21C37/06; B21C37/15; B21D53/06; F28F1/00; F28F21/08; B23P11/02; (IPC1-7): F28F1/00; B21C23/00; B21C37/06; B21D53/06; B23P11/02; F28F21/08

Kiyoshi Minoura

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