Wall Thickness Uneven Experimental Study On Hot Power Backward Spinning For Cast 7075 Aluminium Alloy Tube

Thin-walled high strength aluminum alloy tube with high specific strength, high pressure resistance, corrosion resistance and light weight and other characteristics, has been widely used in aerospace and aviation. The hot power backward spinning(HPBS) is one of the most efficient methods to process manufacture this type of tubes. Cast 7075 aluminum alloy plastic performance of poor and the forming process involving multi field, multi mould, multi factors coupling characteristics that lead to the material prone to wall thickness uneven, crack, bulge and other defects in the hot power backward spinning process. Especially for the wall thickness uneven is one of the key factors. Which so in this paper, the experimental method is used to study the wall thickness of the forming process. The main results are as follows:(1) Based on the orthogonal experiment, the geometric parameters of the roller were optimized. It is found that the crack and bell mouth were produced when the corner radius of roller is 5 mm. The primary and secondary order of the influence of the working angle and the radius of the corner on the thickness of the wall is: working angle > corner radius of roller. Finally get the best combination of roller: Working angle α is 20°, corner radius is 8mm.(2) Influence of forming parameters on the distribution of wall thickness was studied by experiment. It is found that when the total reduction is constant, the degree of uneven thickness of the tube is increased with the increase of the amount of the fourth-pass reduction. The thickness unevenness increases with the increase of preheating temperature. When the rotating speed of the mandrel speed is 100r/min, the crack of the tube is produced. Properly increasing the mandrel speed, the thickness of the wall is also reduced. The wall thickness uniformity of tube increases with the increase of feed rate, and the overall fluctuation range is small. The better the lubrication condition between the mandrel and the tube, the larger the wall thickness uniformity of cylinder.(3) Based on the orthogonal experiment, the forming parameters were optimized. It is found that the primary and secondary order of the influence of forming parameters on the wall thickness uniformity of tube is: reduction> mandrel speed > feed rate > preheating temperature > friction condition. The influence of the mandrel speed and feed rate on the wall thickness of the tube is obviously. Finally, the optimal combination of the forming parameters of the cast 7075 aluminum alloy cylinder is obtained namely reduction(1.7mm);preheat temperature(250℃);mandrel speed(200r/min);feed rate(80mm/min);friction condition(apply a small amount of graphite grease).