New Technology Development On The High Efficiency Butt Jointing Of Crane Board Without Back Chipping

In the production of large cranes,bridges,ships and other equipment,there was a large number of plate unit butt welding.At present,it was mainly used the manual arc spot welding for thick plate welding,used carbon dioxide gas welding to bottom welding,used submerged arc welding to render positive fill covering,work-piece rolled over,carbon arc air gouging root,manual polishing,reverse side submerged arc welding filling cover.The production process of the whole plate unit was complex and the production inefficient production.Based on the above problems,this paper proposed the application of submerged arc welding ceramic liner technology based on the original submerged arc welding technology.Used the technology of submerged arc welding and reverse ceramic liner to realized the double-sided forming of single side welding.Firstly,finite element simulation software MACE was used to simulate the stress field and the temperature field of submerged arc welding.By simulating the temperature field and stress field in the welding process,the welding heat input range was determined.The experimental results show that welding simulation cannot be performed when the welding heat input exceeds 5.0 KJ/mm for a 12 mm plate thickness.Through observing the experiment,it was found that the welding heat input was large,the welding wire melting was fast,and the metal solution in the molten pool was prone to flow out,and the welding leakage phenomenon occurs.In the study,adopted the ceramic liner technology to achieved the double side welding single side forming.At the same time,in order to reduced the amount of welding filler,the groove shape of the box plate unit was V-groove,the angle was 60°,the blunt edge was 4mm,and the groove gap was 3-4mm.Compared with the traditional groove,the welding filling amount was reduced12%.Using double-wire submerged arc welding to replace the traditional single-wire welding method,greatly improve the welding efficiency.The welding process involved 12 mm,16mm and 20 mm plate thickness test plates,and the optimum technological parameters were obtained,and the voltage,current and welding speed of the double wire were given.Experiment of weld specimen by SEM microstructure observation,weld filler zone and base metal zone blend well weld,the joint was not generated twin marten site and westergren body with lower toughness,such as organization,meet production requirement.The test results of tensile,bending,impact and hardness were in accordance with the standard requirements of AWS D1.1-2015.Research showed that: the multiple wire submerged arc welding with ceramic liner technique,positive bedding,padding and covering,negative plate positioning,implement a one-time two layers of single pass welding,simplifies the welding process,well up to the one-side welding of forming effect.