Threaded tubes, also known as low-ribbed tubes, mainly rely on the ribbing outside the tube (coefficient of ribbing is 2-3) to expand the heat transfer area, and are generally used when the coefficient of heat transfer in the tube is more than 1 times larger than the coefficient of heat supply outside the tube. For the outside of the tube condensation and boiling, due to the effect of surface tension, there is also a good strengthening effect.
The heat exchange tube as the core heat exchange element of the heat exchanger improves its heat transfer performance, controls the volume and quality, and saves material. It is of great significance to improve the efficiency of the heat exchanger and reduce the cost. The high-efficiency heat transfer tube technology has generally adopted the threaded pipe, which has the advantages of high heat transfer efficiency, less scale, small size, and material saving compared to the traditional smooth pipe. The long-term operation of threaded pipe under high temperature, high pressure, corrosive gas and other harsh environments has high requirements on its corrosion resistance and stability. At the same time taking into account the difficulty of production methods and processing techniques, copper and aluminum are usually used as threads. Tube material. Although the price of aluminum tubes is lower than that of copper tubes, it has disadvantages such as poor welding processability, poor heat exchange performance, and the possibility of being easily damaged by metal expansion heads when expanding tubes, and has not been widely used. In recent years, with the rise of copper prices all the way, the price of stainless steel has been greatly reduced, and the production process of stainless steel pipes has continued to advance. As a substitute material with superior performance and lower cost, stainless steel threaded pipe has broad application prospects.
Threaded pipe processing methods are generally twisted, rolling, extrusion and rolling method, they are usually used to process large diameter pipe thread, and the processing accuracy is not high. For small heat exchangers with small diameter, thin-walled stainless steel threaded pipe, poor rigidity, small size, obviously can not be processed by traditional methods. Therefore, a new thread processing technology was proposed and a thread automatic processing control system based on PLC and servo system was designed. The control system has high working reliability and automation, high output, and processing accuracy meets requirements, and the operation is simple and convenient.