Large-diameter thin-wall elbow forming method

Abstract

The invention discloses a large-diameter thin-wall elbow forming method. The method comprises the steps that a large-diameter thin-wall pipe blank is bent into a large-bending-radius elbow; the large-bending-radius bent pipe is pressed into an elbow; wherein in the bending process, the mode of local heating, propelling, bending and cooling is adopted. The pipe blank is locally heated and locally deformed through bending forming, the large-bending-radius bent pipe is manufactured, and therefore the collapse pit defect is avoided, and the deformation time period of collapse pits is avoided. After the bent pipe is bent and formed, the bent pipe is pressed and formed, so that the outer arc of the elbow can be effectively prevented from being thinned. The advantages of bending forming and pressing forming are combined, the manufactured finished elbow is high in quality, attractive in appearance, uniform in wall thickness and low in thinning rate, and the defects of collapse pits, cracks, wrinkles and the like are avoided.

Description

technical field [0001] The invention relates to an elbow forming method, in particular to a large-caliber thin-walled elbow forming method. Background technique [0002] The forming of large-diameter thin-walled elbows generally adopts a combination of press forming and over-ball shaping, that is, the steel pipe is pressed into an elbow by pressing the forming process first, but obvious collapse pits often appear at the position from the inner arc to the side arc of the elbow In severe cases, wrinkles will be generated, and the molding appearance is poor; therefore, after pressing and molding, it is necessary to use multiple ball-passing processes to correct the collapse defects. The ball passing process is to press the craft ball from one end of the elbow and press it out from the other end of the elbow, so as to achieve the purpose of shaping the collapse defect. However, when the pit defect is very serious and reaches obvious wrinkles, it is not only difficult to stretch...

AI Technical Summary

Problems solved by technology

However, when the collapse defect is very serious and reaches obvious folds, it is not only difficult to stretch the folds to a smooth state by the simple ball passing process, but the folds may even crack due to excessive deformation, resulting in the scrapping of the elbow

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