Pipe having grooved inner surface, apparatus for producing the same and method for producing the same

Abstract

Provided is a pipe having a grooved inner surface, which has excellent thermal conduction properties, can be made compact and lightweight, and allows resources to be conserved. Also provided are a method and apparatus for producing this pipe having a grooved inner surface, which allow efficient and stable production thereof. The apparatus which is used for producing the pipe having a grooved inner surface is provided with: diameter-reducing means for drawing a base pipe in order to reduce the diameter thereof, and groove-forming means for forming a large number of grooves on the inner surface of the base pipe. If, for example, the angle of twist of a groove with respect to the centre axis of the pipe is beta (DEG) and the apex angle of a fin which is formed between adjacent grooves is alpha (DEG), then beta is between 30 and 60 and alpha is between 5 and 20. If the outer diameter is D (mm), the groove depth is H (mm), and the cross-sectional area with respect to the axial direction of the pipe is Ac (mm<2>), then D is no greater than 6, H is at least 0.07, and Ac is less than 0.8*D.

Description

technical field [0001] The present invention relates to an inner surface grooved tube used as a heat transfer tube for heat exchangers such as refrigerators and air conditioners, and a method for manufacturing the same. Background technique [0002] Heat transfer tubes used in heat exchangers of heat pump equipment such as air conditioners and water heaters are often grooved on the inner surface in order to improve heat exchange performance, such as copper inner surface grooved tubes. [0003] In recent years, in order to respond to the miniaturization and high efficiency of heat exchangers, the grooves formed on the inner surface have been deepened, the helix angle (lead angle) of the grooves has been increased, the fins have become sharper, and the wall thickness of the tubes has been increased. Thinned inner surface grooved tubes to improve heat exchanger performance. [0004] For example, in the following patent document 1, a small-diameter heat transfer tube with an ou...

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Problems solved by technology

[0016] However, even if the overall tensile load can be reduced, when the tensile load changes, it cannot be processed completely corresponding to this load change.

[0017] For example, in the manufacturing device disclosed in Patent Document 6, an intermediate drawing device is configured, and a wiper is provided to prevent the gasket in contact with the substrate from sliding relative to the substrate, and the groove shape of the gasket is specified, but the load variation still remains will happen

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