Welding is a process of permanent joint production by formation of interatomic bonds origination...
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Transcript of Welding is a process of permanent joint production by formation of interatomic bonds origination...
WELDING
Welding is a process of permanent joint production by formation of interatomic bonds origination between the parts being joined.
Friction welding
Welding methods
Welding by fusion
– Gas welding
– Cold welding– Electric arc welding
– Friction welding
Welding by pressure
– Plasma welding – Ultrasonic welding
Plasma welding
а b
U, V
WELDING
Electric arc welding
The welding arc is a powerful stable electric discharge burning between electrodes in the atmosphere of ionised gases and vaporised metals.
Scheme of direct currentwelding arc: 1 – electrode; 2 – base metal;
3 – bath of liquid metal; 4 – arc column
Static volt-ampere arc characteristic (а);external characteristics of current sources for welding (b)
WELDING:
Diameter of electrode d is chosen depending on welded metal thickness: where s is the thickness of welded metal, mm.
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
Electric arc welding
WELDING
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.
Electric arc welding
2 –
WELDING
Resistance butt welding (RW):
1 – current supply clips; 2 – billets; 3 – motionless plate; 4 – mobile plate; 5 –
guide; 6 – welding transformer; 7 – flexible busesAdvantages 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.
Resistance welding
Flash welding (FW)