Question

B1) 20 pts. The thickness of each of the two sheets to be resistance spot welded is 3.5 mm. It is desired to form a weld nugget that is 5.5 mm in diameter and 5.0 mm thick after 0.3 sec welding time. The unit melting energy for a certain sheet metal is 9.5 J/mm². The electrical resistance between the surfaces is 140 micro ohms, and only one third of the electrical energy generated will be used to form the weld nugget (the rest being dissipated), determine the minimum current level required.

Answer 1

Giveni DS 5.5 mm L = 5.0 mm them, Va X (5.5)?x 5 [ va from electric energy Solution: nugget volume (v) = D’I V= 118.73 mm mm3] Required melting Energy (9.5 mm) x (v) (ME) ME = 1127.951) [7 - $) > M.E = 9.5XL 18.73 J Then ME 2 Actual Required Electric Energy ( A.EE) n A.E.F= 1127.95 (5) [A-EF = 3383-84 1] we know that CSScanned with CamScanner

> Electric energy (EE) = I²Rt where, Ia Current R = Resistance ta time then, 3383-84 I?? (240 x176) X0:3 Current (I) = 8975.95 Ampere Ans. CSScanned with CamScanner