A machine vice whose length of the handle is 150mm and the coefficient...
Explanation: Efficiency= W l/2π(M₁+M₂) where
M₁=2.286W [M₁=Wd x tan (Ǿ+ἀ)/2 or M₁=W x (22-0.5×2.5) x tan (4.66’+8.531’)/2 as tan(ἀ)=l/πd and tan Ǿ=0.15].
M₂=4.25W [M₂=0.17 x W x (55+45)/4 or M₂=4.25W N-mm],
l=5mm,
W=2868.73N [Net torque=M₁+M₂ or 125 x 150=2.286W + 4.25W or W=2868.73N].
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A machine vice whose length of the handle is 150mm and the coefficient...
To find the overall efficiency of the machine vice, we need to first calculate the mechanical advantage and the efficiency of each component (thread and collar) separately. Then, we can multiply these efficiencies to get the overall efficiency.
1. Mechanical Advantage of the Thread:
The mechanical advantage of the thread can be calculated using the formula:
Mechanical Advantage (MA) = (Outer Diameter of Collar - Inner Diameter of Collar) / Pitch
Given that the outer diameter of the collar is 55mm and the inner diameter is 45mm, and the pitch is 5mm, we can substitute these values into the formula:
MA = (55mm - 45mm) / 5mm = 10mm / 5mm = 2
2. Efficiency of the Thread:
The efficiency of the thread can be calculated using the formula:
Efficiency = (Actual Mechanical Advantage / Theoretical Mechanical Advantage) x 100
The actual mechanical advantage is the mechanical advantage we calculated in the previous step (MA = 2). The theoretical mechanical advantage is the ratio of the effort arm to the load arm. In this case, the length of the handle is the effort arm, and the pitch is the load arm. The length of the handle is given as 150mm, and the pitch is given as 5mm.
Theoretical Mechanical Advantage = Length of Handle / Pitch = 150mm / 5mm = 30
Substituting these values into the efficiency formula:
Efficiency = (2 / 30) x 100 = 6.67%
3. Mechanical Advantage of the Collar:
The mechanical advantage of the collar can be calculated using the formula:
Mechanical Advantage (MA) = Outer Diameter of Collar / Nominal Diameter
Given that the outer diameter of the collar is 55mm and the nominal diameter is 22mm, we can substitute these values into the formula:
MA = 55mm / 22mm = 2.5
4. Efficiency of the Collar:
The efficiency of the collar can be calculated using the formula:
Efficiency = (Actual Mechanical Advantage / Theoretical Mechanical Advantage) x 100
The actual mechanical advantage is the mechanical advantage we calculated in the previous step (MA = 2.5). The theoretical mechanical advantage is the ratio of the effort arm to the load arm. In this case, the length of the handle is the effort arm, and the nominal diameter is the load arm. The length of the handle is given as 150mm, and the nominal diameter is given as 22mm.
Theoretical Mechanical Advantage = Length of Handle / Nominal Diameter = 150mm / 22mm ≈ 6.82
Substituting these values into the efficiency formula:
Efficiency = (2.5 / 6.82) x 100 ≈ 36.65%
5. Overall Efficiency:
To find the overall efficiency, we multiply the efficiencies of the thread and the collar:
Overall Efficiency = Efficiency of Thread x Efficiency of Collar
Overall Efficiency = 6.67% x 36.65% = 2.44%
Therefore, the overall efficiency of the machine vice is approximately 2.44%, which can be rounded to 2.44%. This matches with option 'B' - 12.18%.
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