Butt welding flange refers to the flange with neck, with round pipe transition and connected with the pipeline by butt welding, which is widely used for welding pressure vessels and pipelines. Radial ring rolling refers to the plastic processing technology of blank with reduced wall thickness, enlarged diameter and shaped section profile under the action of radial ring rolling machine. The radial ring rolling process of butt welded flange is complex. Understanding the forming law of butt welded flange, mastering the influence of blank structure size on the quality of ring rolling, reducing and avoiding the occurrence of rolling defects, has important engineering significance for improving the quality of butt welded flange rings.
This paper takes DN1000-1.6-M24-I butt welding flange as the research object, carries out theoretical analysis and numerical simulation of radial ring rolling of butt welding flange, and designs the blank. The main research contents and achievements are as follows:
1. Preparation of DN1000-1.6-M24-I butt welding flange radial ring rolling process. Through analyzing the process parameters of DN1000-1.6-M24-I butt welding flange, the rolling ratio is formulated, and the blank size is calculated according to the principle of unchanged volume and similar shape. Based on the biting condition and forging penetration condition of the ring, the feed speed and speed range of the ring for a given butt welding flange blank are determined. Within this range, the feed curve of the mandrel roll is deduced by giving the growth curve of the outer radius of the blank. According to the principle of holding angle unchanged, the track of the holding roll is deduced, and the radial ring rolling process of the butt welding flange is formulated.
2. DN1000-1.6-M24-I butt welding flange Numerical simulation of radial ring rolling. According to the above ring rolling strategy, carry out the numerical simulation of the radial ring rolling of the butt welded flange. Through the simulation analysis and comparison of the two working conditions without holding roller and with holding roller, the important role of holding roller is proved. The equivalent stress, equivalent strain nephogram and roll force curve in the ring rolling process are obtained by simulating the working conditions with holding roll. By analyzing the occurrence and development process of plastic deformation, the causes of defects such as warpage and insufficient filling during ring rolling are expounded. The rule of metal flow is summarized, and it is concluded that in the process of radial ring rolling of butt welded flange, the blank neck tends to flow towards the large end face.
3. DN1000-1.6-M24-I butt welding flange blank design. Taking DN1000-1.6-M24-I butt welding flange as the object, according to the above analysis of warpage, underfill and metal flow, the blank design principles are determined, and four blank schemes with different structural dimensions are designed. By analyzing the influence of blank shape and size of butt welding flange on ring rolling quality, it is concluded that the smaller the axial flow of metal is, the easier it is to fill the cavity. Comprehensively compare four schemes, such as the filling condition in the metal mold cavity, the size of roll force, the warpage condition, the difficulty of blank making, etc., and finally determine a more ideal blank, which provides basis and guidance for the design of radial ring rolling blank of butt welded flange.
