Double-layer winding-soldering pipe production technology for connection of indoor/outdoor unit of air conditioner

Abstract

The production process of double-layer coiled welded pipes for the connection of indoor / outdoor units of air conditioners is to lay flat double-sided copper-coated steel strips made of low-carbon interstitial-free steel on the uncoiler; roll the copper-coated steel strips on the forming machine 720° to form a double-layer coiled pipe tube; send it into the brazing furnace, and pass NH3 decomposition protection gas into the furnace for brazing; send the brazed double-layer coiled pipe into the airtight chamber that passes NH3 decomposition protection gas The cooling pipe is cooled, then slowly cooled and further cooled; after that, it is directly sprayed and dried with passivation water; finally, it is collected into a disc shape by a coiler, which is a disc-shaped double-layer coiled welded pipe. Disc-shaped double-layer coiled welded pipe is bright annealed in off-line controlled atmosphere and cut to length. The plastic strain ratio r > 2.0, the strain hardening index n > 0.25, the elongation δ > 45%, and the yield strength δs of the double-layer coiled welded pipe obtained by the production process of the invention are less than 150 MPa. When installed on-site as an air-conditioning connecting pipe, it can realize artificial forming on the installation site of the air-conditioning connecting pipe, and there will be no phenomenon of flattening or wrinkling of the pipe wall.

Description

technical field [0001] The invention belongs to the field of manufacturing engineering, and in particular relates to a production process of a double-layer rolled welded pipe used for connecting indoor / outdoor units of an air conditioner. Background technique [0002] Double-layer coiled welded pipe is a kind of small-diameter thin-walled double-layer straight seam formed by cold-rolled strip steel with double-sided copper plating, rolled at 720° on a special forming unit to form a double-layer coiled welded pipe tube, and then brazed at high temperature. Precision steel pipe. The pipe has the characteristics of high pressure resistance, corrosion resistance, high vibration fatigue resistance, smooth inner surface and low price. It is an ideal pipe to replace copper pipes. It has been produced in my country for nearly 20 years. It was mainly used in refrigerators and freezers in the early stage. Condenser pipes (now gradually replaced by single-layer welded pipes) are curren...

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the existing double-layer coiled welded pipe cannot replace the copper pipe connected to the indoor / outdoor unit of the air conditioner, and provides a lower yield strength, which is more convenient for manual bending and forming, and has good drawing and forming performance. There will be no flattening or wrinkling of the pipe wall, and it is more suitable for the production process of double-layer welded pipes for the connection of indoor / outdoor air conditioners in industrialized mass production.

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