Study On The Equipment And Technics Of Welding With Trailing Peening By Electromagnetic Hammer

The welding as a basic craft and technique of manufacturing has made important contribution for the development of the industrial economy in the 21st century. However, welding is a process of fast heating and cooling in part, which causes the non-uniform temperature field and strain field that produce big welding stress in the welded workpiece. But the existence of welding stress may produce the heating crack, cooling crack and also affect the processing precision and size stability, and affect the welding quality.How to reduce and eliminate welding stress, and avoid welding crack form becomes an important topic in welding field draws much attentions. People proposes many methods of eliminating welding stress, including the heat treatment, the vibration method, the machine stretch method, peening method and so on. As peening method, welding with trailing peening is new technique of reducing or eliminating welding stress through real-time peening the welding joint and the near metal in the welding process. Which can effectively improve the stress distribution condition in the welding joint, reduce the stress concentration phenomenon, prevent the welding heating crack and enhance the anti-tensile strength. Comparing with other reducing stress methods, welding with trailing peening has merit of simple operation, high efficiency, and more advantages are being displayed.In order to perfect welding with trailing peening craft, and realize automatization of welding with trailing peening device. The subject is base on predecessor's research foundation go to study equipment and technics of welding with trailing peening. Firstly, analysed the strengthen principle of welding with trailing peening, and simple expound the welding with trailing peening device. Electromagnetic hammer had been improved, reducing its cubage and enhancing its flexibility. Secondly, through improved the electromagnetic hammer designed its fixture have 3 Degree-of-freedom, and free adjust hammer head with surfacing weld's angle (peening temperature) and peening distance. Fixture which independently designs to drive device carry through welding with trailing peening experiment, through the welding with trailing peening experiment emphasize analyzed the influence of peening. Force peening temperature on welding stress and microhardness, the microstructure of peening before and after workpieces were contrasted and analysed. Finally, the paper discussed the welding temperature field and stress field by using numerical simulation technique.Drawing the below conclusion through the experiment: (1) The welding stress was reduced in the welding joint and the near area remaining, the peak of reducing value is in the welding seam, more far from welding seam, more small of reducing value of stress. (2) From the welding joint microstmcture: welding with trailing peening can thin crystal grain, increases intensity of the welding joint. (3) Based on ansys finite element, adopted submerged arc surfacing welding techniques to simulate welding temperature and stress field, then concluded that thermal circling curves changed in the trend line at welding heat affected zone and along centerline of the welding joint in different sections. temperature generally increase rapidly and then fell until to become stable; longitudinal, transverse residual stress changed in the trend line along centerline of the welding join, but the whole longitudinal stress represented tension stress, as a whole, longitudinal stress is much bigger than transverse stress.