The Continuous Extrusion Forming Internal Thread Aluminum Pipe Technology Research And Equipment Reformation

Inner grooved tube, which is a kind of tube for energy-efficient heat exchange, is widely used in producing wall tubes of high pressure boiler furnace and refrigeration, especially in home appliances and air conditioning for cars. Compared with the ordinary heat transfer tubes with no grooves, inner grooved tubes have several advantages such as large heat dissipating area and high coefficient of heat transfer. At present, there are two main methods for forming inner grooved helical tubes, which are the rolling-welding method and the drawing-spinning method, respectively. The former is still in involving, because of its high cost and poor mechanical property of products, while the latter is developed. The difficulty of producing aluminum inner grooved tubes by employing the drawing-spinning method increases because of its high viscosity. Therefore, the copper inner grooved helical tube is widely used. However, compared with copper and copper alloy, aluminum and its alloy have advantages in low proportion and prices, and aluminum is rich in resources. In terms of heat transfer performance, the cost-effective of inner grooved helical tubes made of aluminum and its alloy is higher. Under the circumstances of high price of copper for a long time and the feasible of copper replaced by aluminum in heat transfer technology, producing inner grooved aluminum tubes by employing continuous extrusion technology can reduce the difficulties and cost in processes of forming, and achieve the target of partially replacing copper inner grooved helical tubes by the aluminum one. Therefore, the process of forming aluminum inner grooved helical tube by employing continuous extrusion proposed in this thesis can create important social and economic benefits.A novel technology of forming inner grooved aluminum tube by combining an initiative rotating punch with CONFORM is proposed in t This thesis. The craft mentioned has several advantages, such as short process, low cost, good performance and precise size of product. The basic process and principle of the forming technology are expounded. This thesis is focus on the research below:①The feasible of forming is analyzed theoretically by establishment of mechanical model.②The continuous extrusion producing line is improved, and the supporting equipments for aluminum continuous extrusion, including the drive mechanism, hydraulic system, automatic speed control system based on PLC technology, coiling wheel and etc., are designed and debugged.③The basis of extrusion die design of continuous extrusion aluminum inner grooved helical tube is theoretically analyzed, and the structure of extrusion die is optimized and checked by results of calculation and analysis of experiments.④The main process parameters and the analytical expression have been determined by analyzing the experiment results, and achieved steady industrial production.⑤Series of key issues in industrial production have been solved, such as the short life of extrusion die and bearing, excessive temperature of the hydraulic system, eccentric of extrusion dies, poor surface quality of production, unsteady of coiling system, measuring unsteady of automatic speed control system, and so on.Up to now, It has a wall thickness ranging from0.35-1.0mm, diameter ranging from7.0-12mm, number of screw less than60and helix angle less than60°is obtained. The technology has successfully been applied in continuous extrusion production line in Jiangsu ALCHA Aluminum CO., LTD and achieved mass production. In addition to continuous extrusion production of inner screw tube and how to form the product types are analyzed, and the next research direction, experiment content and the need to improve the local paper.