Annealing technique for heating electric heating tube

Abstract

The invention relates to an annealing process for an exothermic electrothermal tube, which comprises the following steps in turn: 1) decomposition reaction of an ammonia liquid; 2) temperature rise and ignition of a mesh-belt furnace; 3) annealing; and 4) inspection. The invention hardly consumes water resources in the annealing process of the electrothermal tube, does not use an acid solution which severely pollutes the environment, has good stability of the annealing temperature of products, guarantees the quality, performs bright annealing on stainless steel tubes, manufactures environment-friendly products, reduces the environmental pollution in the manufacturing process, saves the resources, and reduces the loss.

Description

technical field [0001] The invention relates to the manufacture of electric heating tubes, in particular to the annealing process of heating electric heating tubes for manufacturing stainless steel kettle tubes. Background technique [0002] Electric heating tube manufacturers must anneal and soften the outer tube material of the electric heating tube when making the electric heating tube, so that the bending of the electric heating tube can be smoothly performed without breaking. The outer tube material (SUS304) is annealed after empty tube, and then powder filling, tube shrinking, bending tube forming and welding are carried out. The annealing temperature of SUS304 pipe is 1050°C. The commonly used annealing technique is: electrode annealing to soften the pipe. Since a black oxide layer is formed on the surface of the material after high-temperature annealing, the heating tube of the kettle tube is used in drinking water, and the surface of the tube must be kept clean. G...

AI Technical Summary

Problems solved by technology

Since a black oxide layer is formed on the surface of the material after high-temperature annealing, the heating tube of the kettle tube is used in drinking water, and the surface of the tube must be kept clean. Generally, 70% nitric acid solution is used to clean the annealed oxide layer, and the tube is filtered with clean water and dried to achieve cleaning. The purpose of pipe material, but this technology has great disadvantages: 1. The pickling waste liquid seriously pollutes water resources and is not environmentally friendly; 2. The waste of cleaning water is serious; 3. The power and power required for annealing will vary with the grid voltage fluctuation Inconsistency in temperature causes the hardness of the pipe to be different after annealing; 4. Electrode annealing damages the pipe. When making an electric heating pipe, it is easy to cause broken pipe and burst phenomenon