What is the basic principle of resistance welding in hot galvanizing?
In lap resistance welding, two materials are overlapped, pressurized and connected with an electric current, and the heat generated by the resistance of the materials themselves, the resistance between materials and the contact resistance between resistances is utilized to raise the temperature of materials and finally melt and weld them.
The heat generated by welding at both ends can be expressed as: r=0.241Rt=0.24let
Where: Qr 1 heat, card 1 current, ampere R 1 welding area resistance e-plate voltage, volt t- electrification time, seconds
On the other hand, if the thickness of the plate is D., it can be known from the resistance law that R= p-2d./Ss 1 welding area fault area p 1 material resistivity
Since S changes constantly during welding, and p changes with temperature, if the resistivity at a certain temperature is p.P.= the resistivity of the material at Po (1+ao) at room temperature, ae- the resistivity temperature coefficient when the temperature is 8
So the resistivity is p.When the temperature of the material is turned on, its resistivity rises to pa, thus causing further heating. This heat increases the resistivity further, so that the material is melted repeatedly.The resistivity is 1-2 times higher during melting than it was before melting. As a result, current no longer flows through the melted zone, but through the fused compression zone, causing the zone to melt again and the welding to expand.
What are the characteristics of lap seam welding?
The characteristics of lap seam welding are: short welding time, rough welding seam, high joint step, general welding seam is 60% thicker than the original plate, so this method is not used at present.
What are the features and considerations of lap extrusion welding?
Features: the weld is relatively smooth and clean, the joint steps are not significant, generally 10~20% thicker than the original plate, and the tensile strength of the weld is good.Many units are still in use.
Note: select proper electrode pressure, current strength, welding speed and lap when welding