The automobile brake hard tube can shrink longitudinally and transversely at a certain temperature, and the heat shrinkage rate can be controlled between 40% and 60%, making it extremely tight with the steel pipe, thereby effectively preventing acid, alkali, salt, etc. The solution penetrates into the steel pipe. In the above-mentioned automobile brake hard pipe, the steel pipe is wound into two layers by a steel belt. The steel pipe wound into two layers by the steel strip has high mechanical strength and can further resist the erosion of acid and alkali solutions. In the aforementioned automobile brake hard tube, the steel strip is a copper-plated steel strip. After the steel strip is plated with copper, the worn part of the surface can be repaired to make the surface more detailed and smooth, which is convenient for sleeve connection of heat shrinkable tubing and improves the sealing performance.
In the aforementioned automobile brake hard pipe, the outer surface of the steel pipe has a galvanized layer. The chemical activity of zinc is higher than that of iron. When electrochemical corrosion occurs, zinc is corroded first instead of iron. The oxide of zinc is denser and can prevent further oxidation, so galvanized steel pipe has better corrosion resistance. . Compared with the prior art, the automobile brake hard tube is additionally equipped with a heat shrinkable tube made of non-metallic material outside the steel pipe base material. The heat shrinkable tube has the function of shrinking when exposed to heat. When the working temperature of the heat-shrinkable tube rises, the heat-shrinkable tubing will shrink and compress the steel tube to form a good seal with the steel tube, which can effectively prevent the penetration of acid, alkali and other solutions, thereby avoiding the leakage of the brake hard tube .