Mitsubishi Aluminum Company, Ltd.

Ma Aluminum Corporation

Mitsubishi Alumnium Co., Ltd.

Yusuke Nakaura

Yuki Hateruma

Takeshi Sakagami

Hideo Kume

Koichi Ohori

Takuya Okawa

Masayuki Nakamoto

Toshihiro Harata

An inner spiral grooved tube includes: a tube body; and grooves and fins aligned in an inner circumferential direction of the tube body, wherein the grooves and the fins are formed in a spiral along a longitudinal direction, an outer diameter is 3 mm or more and 10 mm or less, a number of the fins is 30 to 60, made of a metal, a cross sectional shape of each of the fins has a rectangular shape having an apex angle of 0±10°, a ratio h/f is 0.90 or more and 3.40 or less, h being a fin height and f being fin width, a ratio c/f is 0.50 or more and 3.80 or less, c being a fin spacing, and an average of the ratio h/f and the ratio c/f is 0.8 or more and 3.3 or less.

Inner spiral grooved tube with excellent heat transfer property and heat exchanger

A heat transfer tube is made of aluminum and includes a streak-shaped Zn diffusion layer () which is spirally formed on a circular outer peripheral surface in a length direction. According to this heat transfer tube, even in a case where rainwater or dew concentration water is intensively accumulated in a portion of the outer peripheral surface in a circumferential direction, it is possible to obtain a sufficient corrosion resistance.

Heat transfer tube, heat exchanger, and method for manufacturing heat transfer tube

An apparatus for producing an inner spiral grooved tube, the apparatus includes first and second bobbins, one of which is an unwinding bobbin and the other of which is a winding bobbin; a floating frame that supports a shaft of the first bobbin; a rotary shaft that supports the floating frame though bearings and rotates in a direction perpendicular to an axis of a bobbin in the floating frame; a revolving flyer configured to invert a tube route of a tubular material between the first bobbin and the second bobbin, to convey the tubular material, and to revolve the tubular material around the floating frame as being supported by the rotary shaft; and first and second drawing dies positioned on a front stage and a rear stage of the revolving flyer, respectively, in the tube route of the tubular material

Method of producing inner spiral grooved tube and apparatus for producing inner spiral grooved tube

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

Production method and production device for tube with spirally grooved inner surface

A method produces an inner spiral grooved tube using a first drawing die, a second drawing die, and a revolving flyer. The method includes two twisting-drawing steps. The first twisting-drawing step forms an intermediate twisted tube by reducing the diameter of a linear grooved tube, which has plural straight grooves formed along the longitudinal direction on its inner surface, by passing the linear grooved tube through the first drawing die and then by revolving the liner grooved tube wrapped around the revolving flyer with the revolving flyer, in conjunction with imparting twist to the linear grooved tube. The second twisting-drawing step forms the inner spiral grooved tube by reducing the diameter of the intermediate twisted tube by passing the intermediate twisted tube, which revolves with the revolving flyer, through the second drawing die in conjunction with imparting twist to the intermediate twisted tube.

The present invention provides a die casting magnesium alloy having excellent heat resistance and castability, and the alloy of the present invention is a die casting magnesium alloy having excellent heat resistance and castability, comprising 2 to 6% by weight of Al, 0.3 to 2% by weight of Ca, 0.01 to 1% by weight of Sr, 0.1 to 1% by weight of Mn, the balance magnesium and unavoidable impurities. According to the present invention, more excellent effects can be obtained in the composition wherein rare earth elements are added to the composition described above.

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Mishima, Japan

Yusuke Nakaura