emmagbales

21.02.2020 • 

Engineering

17.3 The ideal cycle time of an assembly machine is 4 sec. The parts feeder at one of the workstations has a feed rate of 90 components/min and the probability that the components will pass through the selector is 25%. The active length of the feed track (where the high-level sensor is located) is 400 mm. The low-level sensor on the feed track is located 100 mm from the station work head. The components have a length of 10 mm in the feed track direction, and there is no overlapping of parts. Determine (a) How long will it take for the supply of parts to be depleted from the high-level sensor to the low-level sensor once the feeder-selector device is turned off? (b) How long will it take for the parts to be resupplied from the low-level sensor to the high-level sensor, on average, after the feeder-selector device is turned on? (c) What are the time proportions that the feeder-selector device is turned on and turned off?

Ответ:

danessaporter

19.11.2021

Engineering

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(i) 24.4 m

(ii) 2.19 s

(iii) -10.1 m/s²

Explanation:

(i) Kinetic energy = potential energy + work

KE = PE + W

½ mv² = mgh + Fd

We know the resistance force is 5% of the weight, so F = 0.05mg.

We know the slope of the incline is 1/30, so h = d/√(1²+30²).

½ mv² = mgd/√(1²+30²) + mgd

½ mv² = mgd (1/√901 + 1)

d = v² / (2g (1/√901 + 1))

Given v = 80 km/h = 22.2 m/s:

d = 24.4 m

(ii) Given:

Δx = 24.4 m

v₀ = 22.2 m/s

v = 0 m/s

Find: t

Δx = ½ (v + v₀) t

(24.4 m) = ½ (0 m/s + 22.2 m/s) t

t = 2.19 s

(iii) Given:

Δx = 24.4 m

v₀ = 22.2 m/s

v = 0 m/s

Find: a

v² = v₀² + 2aΔx

(0 m/s)² = (22.2 m/s)² + 2a (24.4 m)

a = -10.1 m/s²

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