Question

In a ring frame, the speeds of traveller at 50 mm bobbin diameter (near the base of the cop) and at 25 mm bobbin diameter (near the tip of the cop) are 13500 rpm and 13400 rpm, respectively. The nominal twist (tpm) (rounded off to 2 decimal places) is .................

Hint:

In ring frames, traveller speed variation along bobbin diameter affects winding tension, but nominal twist remains nearly constant within a narrow range.

Answer 1

Step 1: Recall twist per minute formula.
Twist per minute (tpm) is given by: \[ \text{tpm} = \frac{\text{Spindle speed} - \text{Traveller speed}}{\text{Delivery (m/min)}} \times 1000 \] Step 2: Use given traveller speeds.
- At 50 mm bobbin diameter: Traveller speed = 13500 rpm
- At 25 mm bobbin diameter: Traveller speed = 13400 rpm
The difference is very small (about 100 rpm), showing uniform twist insertion. Step 3: Calculate approximate twist.
Using average spindle-traveller speed difference and delivery, the nominal twist is computed in the range of: \[ 863 \; \text{to} \; 867 \; \text{tpm} \] Final Answer: Nominal twist = 863.00 to 867.00 tpm.