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Drawing frame and its machine parts
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- 2. The draw frame The draw frame is the quality filter of the spinning mill errors in the draw frame sliver result inevitably in yarn defect. since quality can no longer be improved after the draw frame the sliver quality at the last draw frame passage is of decisive importance
- 3. Objects of drawframe To straighten the crimped and hook fibers in the card sliver To achieve a fairly through parallelization of the fibers along the sliver axis so that when they came to be spun on the spinning frame they will be evenly drafted and twisted to produce an acceptable yarn To improve the short medium and long term unevenness of the sliver by doubling To produce a more uniform sliver of definite weight/length To reduce the weight/unit length of the card sliver
- 4. A modern drawframe
- 5. Actions Involvedin Draw Frame Drafting: It is the process of increasing length per unit weight of sliver. It is mainly due to peripheral speed of the rollers. Doubling: The process of combing two or more carded sliver into a single form is called doubling. In draw frame m/c generally six slivers are fed to convert into one i.e. six doubling. Drawing: In the cotton industry the term is applied exclusively to processing on the draw frame, where the operation is one of doubling and drafting. Drawing= Drafting + Doubling.
- 7. Tasks ofDraw frame Equalizing Parallelizing Blending Dust removal Equalizing: One of the main tasks of draw frame is improving evenness over short, medium and especially long terms. Carded slivers are fed to the draw frame have degree on unevenness that cannot be tolerated in practice and slivers from the comber contain the “infamous” piecing. It is obscured by draw frame. Equalizing is always performed by a first process, namely doubling and can optionally also be performed by a second process, namely auto leveling. The draft and the doubling have the same value and lie in the range of 6 to 8. Parallelizing: To obtain an optional value for strength in the yarn characteristics, the fibers must be arranged parallel in the fiber strand. The draw frame has the tasks of creating this parallel arrangement. It fulfills the task by way of the draft, since every drafting step leads to straightening the fibers.
- 8. Blending: In additionto the equalizing effect, doubling also provides a degree of compensation of raw material variation by blending. Their results are exploited in particular way in the production of blended yarns comprising cotton or synthetic blends. At the draw frame metering of the individual components can be carried out very simply be selection of the number of slivers entering the machines. Dust Removal: Dust is steadily becoming a greater problem both in processing and for the personnel involved. It is therefore important to remove dust to the greatest practical extent at every possible point within the overall process
- 9. During drafting,the fibers must be moved relative to each other as uniformly as possible by overcoming the cohesive friction. Uniformity implies in this context that all fibers are controllably rearranged with a shift relative to each other equal to the degree of draft. However, such regularity is utopian as regards both the fiber material and the mechanical means available. Drafting operations always run irregularly, and each draft stage will therefore always lead to an increase in unevenness. Drafting is effected mostly on roller-drafting arrangements (Fig. 43). The fibers are firmly nipped between the bottom steel rollers and the weighted top pressure rollers. If the rollers are now rotated in such a way that their peripheral speed in the through flow direction increases from roller pair to roller pair, then the drawing apart of the fibers, i.e. the draft, takes place. This is defined as the ratio of the delivered length (LD) to feed length (LF), or the ratio of the corresponding peripheral speeds:
- 10. V =Ld/Lf=Vd/Vf Where V=peripheral speed of cylinder D=delivery F=feed The drafting arrangement illustrated has two sub drafting zones normally A break draft zone(B):Vb=V2/V3 A main draft zone(A):Vm=V1/V2 The total draft is always the product of the individual draft of the sum V total=V1*V2*V3…….Vn
- 11. Types of draftingarrangement Conventional 4 over4 roller drafting system It is the old model drafting system here 4top rollers are on each one of the 4 bottom rollers. It can be used for all fiber lengths.
- 12. 4 over 4roller drafting system
- 13. 3 over 4roller drafting system The characteristics feature of this arrangement is engagement of the middle pressure roller with two bottom rollers are carried in a common cradle and are not adjustable relative to each other. This types of arrangement is now found mainly in the combing room.
- 15. 3 over 3roller drafting arrangement It was first developed by platt in the 1960 as and still used today. Infect, the pressure bar arrangement is probably the most widely used from of drafting arrangement for draw frame. In the main drafting zone, a spatial guide system is used for short fiber control
- 17. 4 over 3roller drafting arrangement This is also a 3 roller pressure bar drafting arrangement but a forth roller with lower loading is added to the delivery roller to act as a guide. The top roller are uniform in diameter and are large in order to keep the strain imposed on them low.
- 19. 5 over 4roller drag ting arrangement In this arrangement 5 pneumatically loaded pressure rollers rest on two large 90 mm and two small 28 mm non adjustable bottom rollers. The pressure rollers are suspended from two yokes. They have diameter off 39 mm. all though the three middle rollers may be replaced by rollers of 28 mm diameter depending upon the circumstances.
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