Lease Stand
After leaving the creel, the yarn passes through the reed of a lease stand. The lease stand having two reed / comb, out of which one reed is movable up and down, which allows each adjacent yarn end to raise or lowered to form a shed of yarn sheet. Each alternate yarn threaded through alternate reed.A lease string is inserted across the shed formed by the reed, at a specified intervals, may be 1000 m. At this interval, the machines is automatically stops for lea insertions. However, the intervals of lease may be varied within the rope, as per requirement of the technologist. The lease helps in maintain proper leasing in subsequent process, i.e. in long chain beamer. Any cross ends in the rope can be cleared at the lease portions. The operator in long chain beamer can check whether there is any cross end at lease portions. Any broken end, missing end can be properly mended at lease portions. Hence lease is an important consideration in denim productions. Most of the denim technologist use cotton or synthetic filament yarn for lease. The lease strand should not be of coarse count, or thick at any rope, which may cause unusual end breakages in rope dyeing by touching in fingers.
Next the yarn passes through a counter stand or combination of counter stand and condenser tube assembly. Here the yarn sheet is condensed into a bundle. From the counter stand the yarn passing it through a funnel-shaped trumpet. It is located at the rear of the ball warper. Here the total ends of the yarn sheet is collected in a rope form. This rope is wound on a “log”.
In the ball warper, there are two motor driven drive rolls which are geared together. The ball warping log is placed between these two drive rolls and held against the surface of the drive rolls with pneumatic pressure. The log turns as the two drive roll runs. A pneumatic brake attached to the drive rolls stops the rotation of the rolls as and when required or at the time of any end breakages.
Ball warping machine normally uses a chain and dual sprockets in order to give side-by-side motion of the rope during winding onto the log. This side-by-side movement of the chain is provided through mechanical gear in the traverse to the drive roll motor. The traverse movement of the chain is synchronized to the drive roll rotation speed. However, there is a problem of ribbon formation in the log at certain diameter, as it is not possible to vary the speed of rotation of the rope onto the log. The ribboning causes the machine to vibrate until the rope achieve a somewhat more uniform surface across the log.
McCoy Ellison provides a separate AC Inverter controlled motors for the traverse and for drive the rolls. Both are controlled by Programmable Logic Controller (PLC) so that the speed of the traverse is not depends upon the speed of the drive rolls.
Ball Warper Gear-in speed
The maximum gear-in speed of the ball warper depends upon the desired production of a mill. A typical speed is 360 to 400 m/min.
Ball windup
In the ball warping, the yarn passes through the traversing trumpet, which distributes the rope onto the log. The ball warping machine should be such that, there is a minimum of “dwell time” at the end of each traverse stroke. This prevents hanging of the yarn over the ends of the ball and formation of any loops.Balldimension
The relationship between the ball dimensions and the corresponding length of yarn is an important consideration during purchasing of ball warper. The ball length can be calculated with the following formula by assuming a typical yarn density 59 cubic inches per pound.
Ball length in yards = {11.8 x yarn count x ball width x (D2 – d2)} / Endsper rope Where D= Ball diameter in inches,
D= Log diameter in inches
Braking and start-up
At the time of any end breakage, the ball warping brakes are immediately activated by stop motions. This sudden stoppage of the machine may leads to risk of scuffing the ball on the driving drums, unless the brakes are synchronized properly. In the event of rapid start of the machine, there is a chance of yarn scuffed. Some manufacturer incorporates synthetic covered driven drums to minimize yarn scuffing and slipping.
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