Picking and its classification
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This document discusses different types of picking and picking mechanisms used in weaving. It begins with an introduction to picking, which is the process of passing the weft yarn through the warp shed during weaving. It then describes various picking mechanisms including overpicking, underpicking, and cone overpick and underpick mechanisms. The document provides details on how these different mechanisms work to insert the weft yarn through the shed. It concludes with advantages and disadvantages of different weft insertion methods like projectile, rapier, air jet, and water jet looms.
Picking and its classification
- 1. Group members: Md. Al Amin Bsc in textile engineering Daffodil International University Welcome To Our Presentation Topic: Picking & its Classification
- 2. Pick: Pick is a single weft thread in fabric as woven. Picking: The process of passing through warp shed during weaving is called picking. It is the 2nd primary motion in weaving.
- 3. Objective of picking: To insert the weft through the shed. The shuttle must travel in the correct flight path. To maintain pick spacing/PPI
- 4. Negative picking Positive picking 1. over picking 2. Under picking Over pick mechanism - Cone over pick mechanism Under pick mechanisms – a) Side-lever under pick mechanism b) Side-shaft under pick mechanism c) Cone under pick mechanism.
- 5. In this mechanism, a carrier known as shuttle carries the weft yarn in a package called the “pirn”.
- 6. A picking tappet, driven by the bottom shaft and carrying a nose bit, hits a cone, which in turn drives a vertical shaft. From here, the motion is transmitted to the picker through a picking stick and picker. The picker pushes the shuttle into the shed. Overpick mechanism
- 7. bottom shaft ↓ picking lever ↓ The picking arm ↓ shuttle moves ↓ Picking is done ↓ move back after the delivery of a pick.
- 8. In this mechanism, a circular disc carrying a bowl is driven by the bottom shaft. The bowl hits a shoe, which in turn depresses a side lever, and the picking stick is driven. So the picker is pushed and the shuttle is pushed out of its box into the shed. Under pick mechanisms
- 9. A disc carrying a bowl is driven by the bottom shaft. The bowl hits a shoe, which in turn drives the picking stick though a side-shaft lever and connecting lever. The picker is pushed and the shuttle is shot out of the shuttle box into the shed. Under pick mechanisms
- 10. The nose of a picking tappet, driven by the bottom shaft, hits a cone, which in turn drives a side shaft. This in turn pulls a lug strap and picking stick. The picker, connected to the picking stick, is pushed and so the shuttle emerges from the shuttle box and traverses the shed. Under pick mechanisms
- 11. In throw shuttle process weft yarn is pas one side to another side completely by hand
- 13. In this mechanism, the weft yarn is inserted through the warp shed directly or positively by air, water, a projectile, a rapier or a needle
- 14. a small depth of shed Low Warp thread breakage. Pirns are not required. saving in floor space and labour. Produce high quality fabric
- 15. 1. increasing motor seed. 2. increasing the nose shape of picking tappet. 3. decreasing the length of picking arm.
- 16. 1) PROJECTILE(GRIPPER):- The picking action is accomplished by a small Bullet like Gripper(Projectile), which grips the weft yarn & carries it through the shed. Several gripper are normally used in the loom , while one is crossing the loom with the weft yarn, the others are return to the starting position. The return by conveyer chain.
- 17. Low power consumption Reduced waste of filling Quick warp and change style Easy operation , maintenance and low spare parts requirements Energy saving Different designs and color sequences can be woven. 17
- 18. DRAW BACK OF PROJECTILE:- The dragging of the weft yarn across a loom creates strain on the yarn so projectile loom are not suitable for weak yarn.
- 19. 2)RAPIER:- A Rapier loom use a Rapier to pull the weft yarn across the loom. For a single Rapier a long rapier device is required to extend across the full width of warp. Two rapier enter the shed from opposite side of loom & transfer the weft yarn from one rapier to another rapier near centre of loom. Double Rapier further divided into two categories 1) Flexible Rapier & 2) Rigid Rapier
- 21. 3) AIR JET ;- A loom in which the weft yarn is propelled through the shed by means of a jet of air. Nozzle are used to insert the weft yarn into the shed. The Fabric width of Air Jet loom is normally narrower than Rapier or Projectile loom. DRAW BACK;- Air jet loom cannot produce great variety of fabrics.
- 22. Multiphase loom continually inserts weft yarns from yarn carriers.
- 23. 4) WATER JET LOOM:- In this water is shoot under high force & with it a weft yarn. The force of water as it propelled across the shed cross the yarn to opposite side .. In water jet unit use vacuum suction & heat to remove water from the fabrics. Only use for Hydrophobic fibres.
- 25. High Efficiency Low Maintenance Smooth and Quiet Total Safety