Abstract: Disclosed is a producing method which allows low-cost and highly productive production of a seamless tube with a grooved inner surface having a smooth outer surface and an inner surface formed with plural types of grooves such that a protrusion is not formed at the produced seamless tube with a grooved inner surface. The tube is reduced in diameter by using a die and a plug. Then, the outer surface of the tube is pressed against a grooved plug by means of a pair of rolls such that a groove is formed in a portion of the inner surface of the tube. The process flattens the cross-sectional configuration of the tube in the direction in which the tube is pressed with the rolls. Subsequently, a sizing process using a die is performed with respect to the tube such that the tube has a generally circular configuration.

Abstract: An apparatus for producing an internally grooved seamless tube by rolling. The apparatus has pressing rolls 3 and back-up rolls 20, which work with a constant load under control by the load detector 21 to form uniform grooves without breaking the mother tube.

Abstract: Disclosed is a producing method which allows low-cost and highly productive production of a seamless tube with a grooved inner surface having a smooth outer surface and an inner surface formed with plural types of grooves such that a protrusion is not formed at the produced seamless tube with a grooved inner surface. The tube is reduced in diameter by using a die and a plug. Then, the outer surface of the tube is pressed against a grooved plug by means of a pair of rolls such that a groove is formed in a portion of the inner surface of the tube. The process flattens the cross-sectional configuration of the tube in the direction in which the tube is pressed with the rolls. Subsequently, a sizing process using a die is performed with respect to the tube such that the tube has a generally circular configuration.

Abstract: A tube having a grooved inner surface capable of achieving high condensing performance and high evaporating performance even in a region of a small flow rate of a refrigerant and preferable as a heat exchanger tube for a condenser as well as an evaporator and its fabrication method, wherein spiral groove fabricating zones 1 formed with spiral grooves are arranged at an inner surface of a metal or an alloy tube and intersecting groove fabricating zones 2 formed with intersecting groove groups intersected with pluralities of grooves are arranged at the inner surface of the metal or the alloy tube at regions different from each other, singles or pluralities of the spiral groove fabricating zones 1 and the intersecting groove fabricating zones 2 are alternately arranged in a tube circumferential direction of the metal or the alloy tube, when a fabrication width of the spiral groove fabricating zone 1 in the tube circumferential direction is designated by W1 and a fabrication width of the intersecting groove fabri

Abstract: Disclosed is a heat transfer tube with grooves in an inner surface thereof, which is excellent in both evaporation performance and condensation performance. In the heat transfer tube with grooves in an inner surface thereof according to the present invention, groove processing regions 1 having a width W1 and groove processing regions 2 having a width W2 are alternately arranged in the inner surface thereof, and a linear groove region 3 having a width W3 extending in a longitudinal direction of the tube is arranged between the groove processing region 1 and the groove processing region 2. The width W1 is larger than the width W2. A group of grooves within the groove processing region 1 are helically formed at a torsional angle .theta.1 with respect to a longitudinal direction of the tube, and a group of grooves within the groove processing region 2 are at a torsional angle .theta.2 different from .theta.