Research On The Forming Process Of TP2Inner-grooved Copper Tubes

TP2copper has good properties of thermal conductivity, corrosion resistance andmachinability. It can be widely used in the heat exchanger and condenser of air-conditioninerafter being manufactured into inner-grooved copper tubes which belong to the category ofprecision devices. Inner-grooved copper has strict requirement of size tolerance to the tubeexternal diameter, wall-thickness and tooth height. Currently, inner-grooved copper tubes aremostly formed by the method of ball spinning. However, there are still a lot of defects easilyformed in the forming process due to its complex forming mechanism with this method.Therefore, it is necessary to research the forming process of TP2inner-grooved copper tube.Finite element models of inner-grooved ball spinning were established in this paper withthe simulation software of MSC.Marc and Deform separately, which was based on the forceanalysis of grooved plug in the forming process of inner grooves. Law of metal flow, reasonsof folding and notch defect were analyzed. Simulation results showed that the smallestcircumferential and radial displacements of metal flowing happened at the left cogging filletwhere its filling effect was the best, and the middle position of cogging took the second place.But the filling effect of metal at the right cogging fillet was the worst due to the maximalcircumferential and radial displacements of metal flowing. The main processing parametersincluding motor speed, drawing speed and spinning position which caused folding and notchdefect were obtained.Inner-grooved forming experiment of TP2copper tube has been carried out. Through theexperimental research, the influence of motor speed, drawing speed and spinning position onthe forming quality of inner grooves were analyzed respectively. Then the three mainprocessing parameters of tube φ7.00×0.24(external diameter×wall-thickness) were optimizedwith the method of orthogonal design experiment. Experimental results showed that theheight of inner-grooves was increased with the increase of drawing speed, but decreasing withthe increase of motor speed and spinning position. However, the depth of folding defect wasdecreased first and then increased with motor speed, drawing speed and spinning positionincreasing. For the copper tube of φ7.00×0.24, the speed of motor and drawing should be controlled at23000r/min and30m/min respectively, and the spinning position should be about1mm away from the center position of grooved plug.The forming condition of tooth height under different process parameters was predictedthrough BP artificial neural network which was based on the genetic algorithm. Theprediction results showed that the network can be met the precision requirement.In addition, two-dimension finite element model of Junker roller hearth annealingfurnace was established by the software Fluent. Temperature field and flow field distributedin the annealing furnace were analyzed. Reasons of temperature difference which exited in thelongitudinal direction of annealing furnace and in the transverse direction of copper coil tubewere investigated. Eventually, improvement measures were given in this paper.