Research On The Thin-walled Workpiece’s Forming Method And Defect Controlling Of The Accurate Spinning

The application of large slenderness ratio thin-walled cylinders with a bottom is more and more widely, the product performance and quality requirements of such parts are also higher and higher. The traditional methods of forming such parts exist the limitation of lots of dies, complex process, low precision, poor quality and low production. Compared with the traditional methods, the significant advantage of composite spinning is the ability to effectively reducing tooling investment, avoiding welding technology and improving the product quality.In this paper, regarding a large slenderness ratio thin-walled cylinders with a bottom as the research object, the composite spinning method including multi-pass drawing spinning and flow forming was put forward based on the analysis of the traditional methods; The influence law of the different process parameters on product’s quality (average thickness, maximum wall thickness reduction rate, ovality, straightness) in the the process of multi-pass drawing spinning and flow forming was studied through the method composed by theoretical analysis and experimental study. Then the causes and prevention measures of the typical defects in composite spinning were studied. The main contents and conclusions are as follows:1、The traditional methods of forming large slenderness ratio thin-walled cylinders with a bottom were discussed, including deep drawing, deep drawing+welding forming, multi-pass drawing spinning. On this basis the composite spinning method composed by multi-pass drawing spinning and flow forming was put forward. Then the specification of the roller’s trajectory in the multi-pass drawing spinning was ensured.2、According to the theoretical analysis and practical experience, the toolings used in the composite spinning was designed, and the rational spinning process parameters were determined. The influence law of the different process parameters on products’ quality in the the process of multi-pass drawing spinning was studied regarding the part’s maximum wall thickness reduction rate, ovality, straightness as the evaluation index. The results show that the product’s quality is better when the feed rate∫is bigger, the elevation of the first pass θ0and the space between each pass p are smaller in a reasonable range.3、The influence law of the different process parameters on product’s quality in the the process of flow forming was studied regarding the parts’average thickness, maximum wall thickness reduction rate, ovality, straightness as the evaluation index. The results show that within reasonable limits, the spindle speed has few effect on the parts’quality; With the increases of the roller’s feed ratio, the wall thickness increases, the maximum thickness decrease rate decreases first and then increases, the ovality and straightness are increased first and then decreased; With the increase of wall thickness reduction rate, the parts’maximum wall thickness reduction rate decrease, the ovality and straightness are gradually increased, and the parts’forming quality is reduced.4、The causes and prevention measures of the typical defects in composite spinning were studied., including wrinkling, cracking in the process of multi-pass drawing spinning and cracking, peeling, corrugation in the process of flow forming.