Drawing Frames (LSS)1325236457536845734.pptx

draw frame

1. Drawing Frames Objects of jute drawing frames: 1.Straightening of fibres in the silver 2.Parallelization of fibres in the silver 3.To reduce the weight per unit length of sliver 4.To reduce the thick & thin places in the sliver

2. Main functions of drawing frame: Drawing . The regular & uniform elongation of the sliver is called drawing. Drawing takes place between retaining roller & drawing roller . Doubling: To produce one sliver from two or more sliver is called doubling. It is done by doubling plate . Drafting: Ratio of the surface speed of deliver (drawing) roller & feed (retaining roller is called-drafting.

3. Definition terms :

4. Reach : The distance between the center of the front back roller (retaining) to the bite of the front (drawing) & front pressing roller is known as reach of the drawing frame. The reach should be slightly longer than the longest fibre in the sliver.   Nip : the distance between the foremost gill where the pins leave the sliver and the bite of the front pressing roller is called “Nip”. The distance should be as short as possible. Pitch of faller : the distance between the one row of pins of one faller bar to pins of next faller bar is called pitch of faller.

5. Lead% : The difference in the surface speed of fallers over surface speed of retaining roller to give sufficient tension to the sliver is known as lead percentage. This lead should not be more or less . This faller bar lead% is generally 10 – 15%.

6. Desirable features is any type of drawing frame: An ideal method of pinning the slivers that is the gill pins must enter and leave the sliver as nearly perpendicular as possible. Small lead of gills or fallers to avoid undue tension on the sliver between the faller bars and retaining rollers. Shortest possible nip to give maximum possible control of fibres in drafting Freedom of movement of fibres in the drafting zone. Reliability of the working parts . High speed of fallers permitting maximum production Less noise of fallers when working

7. Types of drawing frames 1.Conventional Draw Frame: According to faller bar propelling mechanism there are 2 types of drawing frames . Push bar type drawing frame Spiral drawing frame 2. Modern Draw Frame: There are two type of modern jute drawing frame, namely- Variable draft draw frame. Gardella 18-M model.

8. Mack High Single Crank Push Bar First Drawing Frame:

9. Material Passage of the Machine: This is a high speed type push bar 1 st drawing frame having 2 heads, 4 sliver per head, 2 deliveries per head, doubling 2:1 . The machine can be roll-fed. For the roll feeding a roller feeder (fluted feed roller) is necessary. Again the delivery may be taken in roll form by a roll-former at the delivery end. The sliver feed end pass side by side over the feed plate and then under the back retaining roller, over the slip roller and again under the front retaining roller. The slivers then pass over the moving gills being penetrated in their pins at the centre . After necessary drafting the slivers pass between the drawing and drawing pressing rollers to the doubling plate. Here the slivers are grouped in equal numbers for doubling. Then they are passed through a pair of delivery rollers and at last collected in roll former by a roller former.

10. Jute 2 nd Draw Frame (Spiral type double threaded) This is a drawing frame having 3 head, 6 slivers per head and 2 deliveries per head. So here doubling ratio is 3:1 i.e. here 3 slivers are doubled into one.

11. Topics 1 st draw frame 2 nd draw frame 3 rd draw frame   1. No of head 2 3 5 2. No of sliver feed/head 4 6 8 3. No of delivery /head 2 2 4 4. Doubling ratio 2:1 3:1 2:1 5. Deliver sliver weight 3-5 5-7 7-9 6.Crimping arrangement Absent Present Present 7. Concentrated can packing arrangement. Absent Present Present 8. Faller bar pitch. ½” ½” 3/8” 9. Production/ hour/m/c 600-650 lbs 600-650 lbs 400-450 lbs 10. Doubling process. At delivery end At delivery end At feed end. Auto stop motion. At both feed and delivery end At feed end. At delivery end. 12. Change pinions in m/c. Surface change, draft change, variable v-pulley. Surface speed change, draft change. Surface speed change draft change.

12. Comparison between push bar and spiral draw frame: Topic Push bar draw frame Spiral draw frame Faller drop Faller drops up to 850/min Faller drops in double screw up to 400 drops/min and triple screw up to 650 drops /min. Lead Faller bar lead over retaining rollers 4-10 Faller bar lead 1.5-4.5 Sound No sound while running Noisy Cleaning Tends to clog with dirt Self &Cleaning because of the jerk at each drop. Pinning In modern type m/c, pinning is good. Excellent laps lapping Laps occasionally, Specially with light slivers Seldom laps Draw frame 1 st draw frame is push bar 2 nd and 3 rd draw frames are spiral type.

13. Crimping Box in Draw Frame

14. In 2 nd and 3 rd drawing frame of jute we see that there is a crimping box after the sliver emerges out the delivery rollers. Necessity Of Crimping Box: In case of cotton we see that cotton has some natural convolutions. So it needs not to be crimped. But in case of jute we see that jute has no natural crimp. So as the draw sliver of jute comes out from flaw frame its count is reduced and it becomes mare and more fragile when it emerges out from the finisher draw frame, it is in so tenuous form that it becomes impossible to handle and it can not be carried up to the back of the spinning frame. So to overcome this problem, the sliver is crimped to give a certain amount of cohesion and strength to the strand. This crimping is imparted to the draw sliver by crimping box.

15. Crimping Process: In this figure below a crimping box is shown which is attached to the delivery of a finisher drawing frame . The sliver leaves the nip of the drafting rollers and passes down the sliver plate into the nip of a pair of fluted delivery roller. The upper roller is spring loaded and positively driven through a wide pitch gear from the lower one . The sliver is driven into a box where it meets a metal finger or lid which is hanging down into the box. The finger hinders the motion of sliver and the box is filled quickly. When more sliver entes the back of the lid of the box. The sliver is forced up by the mass of sliver in side the box. So the sliver at the front of the box comes out . This is a continuous process. During its sojourn in the box the fibers of the sliver becomes concertina and take on a permanent crimp or wave . The time of staying the sliver inside the box can be regulated by means of a small weight which can be added to the finger. A heavy weight on the finger required greater mass of sliver to lift the finger up and hence develops greater amount of crimp in the fibers.