Tappet Shaft Angular Velocity Calculation
This solution determines the angular velocity of the tappet (cam) shaft for a shuttle loom based on its operating speed and the type of fabric produced.
Understanding Loom Speed and Tappet Shaft Mechanics
- The loom speed is given as 180 picks per minute. This is the rate at which weft yarn is inserted.
- The tappet shaft controls the shedding motion (lifting and lowering of warp threads).
- The fabric type is a 3 up 1 down twill. This weave has a 4-end repeat cycle.
- It is assumed that for this specific weave and mechanism, the tappet shaft completes one full revolution for every 4 picks inserted by the loom. This links the loom's operational speed to the tappet shaft's rotational speed.
Calculating Tappet Shaft Rotational Speed
- Step 1: Calculate Tappet Shaft Speed in RPM
Divide the loom speed (picks per minute) by the number of picks per tappet shaft revolution.
$ \text{Tappet Shaft RPM} = \frac{\text{Loom Speed (picks/min)}}{\text{Picks per Revolution}} = \frac{180}{4} = 45 \text{ RPM} $ - Step 2: Convert RPM to Revolutions Per Second (RPS)
Divide the RPM by 60.
$ \text{Tappet Shaft RPS} = \frac{45}{60} = 0.75 \text{ RPS} $ - Step 3: Calculate Angular Velocity in Radian Per Second (rad/s)
Multiply the RPS by $2\pi$, as one revolution equals $2\pi$ radians.
$ \omega = \text{Tappet Shaft RPS} \times 2\pi $
$ \omega = 0.75 \times 2\pi \text{ rad/s} $
$ \omega = 1.5\pi \text{ rad/s} $ - Step 4: Determine the Numerical Value and Round
Using $\pi \approx 3.14159$, calculate the value.
$ \omega \approx 1.5 \times 3.14159 \approx 4.712385 \text{ rad/s} $
Rounding to two decimal places gives 4.71 rad/s.
This calculated value of 4.71 rad/s falls within the expected range.
Important Questions from FABR Loom Mechanisms Shedding
- Group I lists the components of the weaving machine and Group II lists their functions. Match the component with its function.
Group I Group II P Conjugate/matched cams 1 Driving the cloth roller with slip
driveQ Worm and worm wheel 2 Continuous positive take up
motionR Friction clutch device 3 Motion of sley in rapier loom S Lease rod 4 Separation of the warp sheet
forming the shed Amongst the following, the correct condition(s) that will reduce bumping during weaving is/are
- Group I lists weaving machine related parameters and Group II contains the shortcomings of these parameters. Match the machine related parameter with its shortcoming.
Group I Group II P. Variable heald staggering 1. Not favourable for heavy fabric Q. High eccentricity ratio 2. Reduction in shed height R. Fixed heald staggering 3. Reduction of sley dwell S. Late shedding 4. Higher vibration in weaving machine Group I gives a list of loom motions and Group II contains loom systems. Match the motion from Group I with the corresponding system from Group II.
Group I Group II P. Shedding 1. Matched cam Q. Picking 2. Seven wheel R. Beat-up 3. Rapier S. Take-up 4.Jacquard Determine the correctness or otherwise of the following Assertion [a] and Reason [r]
Assertion: In shuttle loom, late shedding is preferred for filament weaving.
Reason: In late shedding, the timing of shed dwell matches with the timing of shuttle travel through the shed, and therefore, it minimises the rubbing of warp yarns.
