1
GATE PI 1992
Fill in the Blanks
+1
-0
Filler material is ......... A...... in resistance welding and the heat generated in the process is directly proportional to ........ B.........

(A). used / not used$$\,\,\,\,\,\,\,\,\,$$ $$\,\,\,\,\,\,\,\,\,$$ (B). square of the current / cube of the current

2
GATE PI 1992
Subjective
+2
-0
3
GATE PI 1992
Subjective
+5
-0
Two sheets of low carbon steel $$1.5mm$$ thick each are spot welded by passing a current $$10000$$ amps for $$5$$ cycles in $$50$$ $$Hz$$ main supply.

i) What is the heat generated due to the supply of power if effective resistance has $$200$$ micro ohms,

ii) The maximum indentation is $$10\%$$ of sheet thickness and density of the spot weld nugget $$8$$ $$gm/cc.$$ If $$1380$$ Joules are required to melt $$1gm$$ of steel, determine heat required for welding operation if $$D=6SQRT$$ $$(t)$$ to determine nugget diameter $$D$$ and assume the nugget size to be equal to metal between the two electrodes

4
GATE PI 1992
Subjective
+5
-0
In $$MIG$$ welding the power source characteristics is $${V_p} = 36 - {\rm I}/60$$ and the arc characteristics is $${V_a} = 2{L_a}\,\,\,\, + 27.$$ Find the change in power of the arc if the arc length changed from $$2mm$$ to $$4mm.$$ If the maximum current capacity of the power source is $$300$$ Amps, the maximum arc length sustainable is
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