Technique for producing double-layer copper brazing steel tube for air-conditioner

Abstract

The invention relates to double-layer brazing steel-pipe production technology used for an air conditioner. A slitting double-side copperizing steel band made of low-carbon interstitial free (IF) steel is horizontally placed on a decoiling disc and is coiled and rolled on a forming machine in an angle of 720 DEG to form a double-layer curly brazing pipe barrel, the double-layer curly brazing pipebarrel is sent to a brazing furnace, decomposition protective gas NH3 is led to the brazing durance to braze, and a brazed double-layer curly brazing pipe is led to a closed cooling pipe internally filled with the decomposition protective gas NH3 to be cooled and then slowly cooled and further cooled; then the double-layer curly brazing pipe is directly sprayed by passivating liquid and then dried; finally, the double-layer curly brazing pipe is coiled by the reeling machine into a coil, conventional continuous acid copperization is carried out on the surface of the double-layer curly brazingpipe after annealing, and the inner wall of the double-layer curly brazing pipe is repeatedly washed by chloroform or carbon tetrachloride to obtain a double-layer copper-brazed steel pipe which meets the operating requirements. Furthermore, the double-layer copper-brazed steel pipe obtained from the production technology has the plastic strain ratio r of being more than 2.0, the strain hardeningexponent n being more than 0.25, the specific elongation delta being more than 45 percent, and the yield strength deltas being less than 150MPa. Besides, the corrosion resisting time of a neutral salt spray (NSS) testing is more than 500h, and a corrosion resisting protective layer can not be damaged under the temperature between 700 DEG C and 900 DEG C.

Description

technical field [0001] The invention belongs to the field of manufacturing engineering, and in particular relates to a production process of double-layer copper-welded steel pipes for air conditioners. Background technique [0002] Double-layer brazed steel pipe (also known as double-layer coil welded pipe) is made of cold-rolled strip steel after double-sided copper plating, rolled on a special forming unit at 720° to form a double-layer brazed steel pipe tube, and then brazed at high temperature A small-diameter thin-walled double-layer straight seam 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 currently...

AI Technical Summary

Problems solved by technology

[0007] The object of the present invention is to provide a production process of double-layer brazed steel pipes for air conditioners, which can not only produce the internal piping of the outdoor unit of the air conditioner, but also produce the connecting pipes of the indoor / outdoor unit of the air conditioner, and not only solve the problem of replacing copper pipes with double-layer brazed steel pipes It is easy to bend and form by hand, and solves the problems of cleanliness of the inner surface of the pipe and anti-corrosion of the outer surface, so that the double-layer brazed steel pipe can be directly applied to the air conditioner

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