Question:-
The maximum heat in resistance, welding is at the
Option (A)
tip of the positive electrode
Option (B)
tip of the negative electrode
Option(C)
top surface of the plate at the time of electric contact with the electrode
Option(D)
interface between the two plates being joined
Correct Option:
(D)
Question Solution:
The heat generated in the resistance welding can be expressed as : H = KI2 Rt
Where;
H = The total heat generated in the work J,
I = electric current (A),
t = time for which the electric current is passing though the joints (s),
R = Resistance of the weld (ohms),
k = A constant to account for the heat losses from the welded joint.
The resistance of the joint R is a complex factor to known, because it is composed of
(a) The resistance of the electrodes:
(b) The contact resistance between electrode and w/p
(c) The contact resistance between two w/p plates.
(d) The resistance of the w/p plates.
The only place where a large amount of heat is to be generated, to have an effective fusion is at the interface between the two w/p plates.