A speed frame with all the drafting rollers of 25.4 mm diameter has the following process parameters: Roving count – 1.5g Ne; Front drafting roller speed – 220 rpm; Roving diameter – 3.0 m; Roving Twist Multiplier – 1.2 tpi Ne-1/2, Empty bobbin diameter – 76.2 mm.
Question 49 (Textile Engineering & Fibre Science)
The ideal bobbin rack speed for the first layer of roving being directly wound on the empty bobbin will be approximately
| (A) | 220 mm/min |
| (B) | 240 mm/min |
| (C) | 260 mm/min |
| (D) | 280 mm/min |
[Show Answer]
Diameter of all drafting rollers(D)=25.4 mm
Roving count=1.5s Ne
Roving diameter=3.00 mm
Front roller speed(N)=220 rpm
Empty bobbin diameter=76.2 mm
Let bobbin speed=N rpm
For first layer of roving being wound-
Surface speed of empty bobbin=surface speed of the front rollers
Bobbin speed x dia of empty bobbin=Front roll speed x dia of roller
N x 76.2=220 x 25.4
N=220 x 25.4 /76.2
N=5588/76.2
Bobbin speed(N)=73.33 rpm
Now,
Ideal bobbin rack speed=Bobbin speed x dia of roving
Ideal bobbin rack speed=73.33 x 3
Ideal bobbin rack speed=220 mm/min (Ans)