WELDING Welding is a process of permanent joint
- Slides: 5
WELDING Welding is a process of permanent joint production by formation of interatomic bonds origination between the parts being joined. Welding methods Welding by fusion Welding by pressure – Electric arc welding – Cold welding – Gas welding – Friction welding – Plasma welding – Ultrasonic welding Plasma welding Friction welding
WELDING Electric arc welding U, V а Scheme of direct current welding arc: 1 – electrode; 2 – base metal; b Static volt-ampere arc characteristic (а); external characteristics of current sources for welding (b) 3 – bath of liquid metal; 4 – arc column The welding arc is a powerful stable electric discharge burning between electrodes in the atmosphere of ionised gases and vaporised metals.
WELDING: Electric arc welding Manual metal-arc welding circuit diagram: 1 – A. C. mains supply; 2 – neutral; 3 – live; 4 – fused switch; 5 – primary cables; 6 – current control; 7 – welding set; 8 – welding cable; 9 – electrode holder; 10 – electrode; 11 – work-piece; 12 – work support; 13 – return current cable; 14 and 15 – earth Diameter of electrode d is chosen depending on welded metal thickness: where s is the thickness of welded metal, mm.
WELDING Electric arc welding 2– Automatic submerged arc welding (SAW): 1 – sliding conductor ; 2 – feeder; 3 – welding wire; 4 – liquid slag; 5 –layer of flux; 6 – slag crust; 7 – welded seam; 8 – basic metal; 9 – pool of liquid metal; 10 – arc zone Advantages of the process: – the most productive way of welding; – high quality of a seam; – low production cost of 1 m of seam; – welding metal up to 20 mm thickness for one pass without cutting of edges. Application: in serial and mass production, such as manufacturing of boilers, tanks, ship hulls, bridge beams, welded pipes with a direct and a spiral seam, wheels.
WELDING Resistance welding Resistance butt welding (RW): 1 – current supply clips; 2 – billets; 3 – motionless plate; 4 – mobile plate; 5 –guide; 6 – welding transformer; 7 – flexible buses Flash welding (FW) Advantages of the process: – cleaning of surfaces is not necessary; – welding parts of a complex section and with the different shape of the section; – dissimilar metals can be welded. Application: welding of rings, wheels, the end tool (drills, mills, taps), rods, rails, reinforcement, pipes.
