1
GATE ME 1999
MCQ (Single Correct Answer)
+5
-1.5
In butt welding operation on plates, the heat input necessary is given by GATE ME 1999 Production Engineering - Welding Process Question 1 English

$$Q = 8\,K\,{T_c}\,t\,\,\,\left[ {0.2 + {{Vb} \over {4\alpha }}} \right]$$
Where $$K=$$ thermal conductivity,
$${T_c} = $$ temp increases from room temp up to $$MP,$$
$$t=$$ thickness of plate,
$$V=$$ welding speed,
$$b=$$ width of weld,
$$\alpha = thermal diffusivity

Two alloy steel plates as shown in fig are to be welded using a power source rated at $$5$$ $$kVA$$ having a duty cycle of $$75\% .$$ Using the given data, determine the maximum welding speed for the job given in $$mm/s$$

Data : $$K = 45\,W/{m^0}C,\,\,{T_c} = {1450^ \circ }C,$$ and
$$\alpha = 1.2 \times {10^{ - 5}}\,\,{m^2}/s.$$

A
$$14.2$$
B
$$19.0$$
C
$$10.65$$
D
none
2
GATE ME 1998
MCQ (Single Correct Answer)
+5
-1.5
The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.

The arc power at an arc length of $$5mm$$ is

A
$$10$$ $$kW$$
B
$$14$$ $$kW$$
C
$$20$$ $$kW$$
D
$$80$$ $$kW$$
3
GATE ME 1998
MCQ (Single Correct Answer)
+5
-1.5
The voltage-arc length characteristics of a $$DC$$ arc is given by $$V=20+4L.$$ Where $$L$$ is in $$mm$$. During a welding operation arc length is expected to vary between $$4$$ and $$6$$ $$mm$$ with the welding current limited between $$450$$ and $$550$$amps.

If the power source has a linear characteristic, the open circuit voltage is.

A
$$36$$ $$V$$
B
$$44$$ $$V$$
C
$$72$$ $$V$$
D
$$80$$ $$V$$
4
GATE ME 1997
Subjective
+5
-0
Welding of $$C40$$ steel plate of $$10mm$$ thickness required a current of $$16$$amps, while it was $$360$$amps when the plate thickness was increased by $$50\% $$. Estimate the welding current for $$8mm$$ thickness of same material.
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