Projectile Loom

A projectile loom is a type of shuttleless weaving machine used in the textile industry to produce woven fabrics. Unlike traditional shuttle looms, projectile looms eliminate the need for a shuttle to carry the weft yarn across the warp threads. Instead, they use a small metal device called a projectile to propel the weft yarn through the shed (the opening formed by the raised and lowered warp threads)

Key Features and Advantages:

Features:

  1. Power Consumption: Utilizes 3 kw-hr of power.
  2. Accumulator Usage: Employs an accumulator to ease weft yarn tensions during insertion.
  3. Number of Projectiles: Typically equipped with 11 to 17 projectiles.
  4. Width Range:
    • Minimum: 190 cm
    • Maximum: 540 cm
  5. Popular Widths: Commonly used widths include 190 cm and 330 cm.
  6. Common Widths: Also utilized at 190 cm and 220 cm.

Weft Insertion System in SULZER Loom (Projectile Loom):

Main Components of Weft Insertion Mechanism:

  1. Projectile
  2. Projectile Feeder
  3. Tensioner
  4. Weft Brake
  5. Selvedge Gripper
  6. Scissor
  7. Tucking Needle
  8. Receiving Unit
  9. Guide
  10. Picking Stick
  11. Accumulator

Mechanism Steps:
a. Projectile (1) moves to the picking position.

  • The projectile is positioned for the next pick.

b. Projectile Feeder (2) opens after gripping the weft end.

  • The feeder opens as it grips the end of the weft presented to it.

c. Projectile draws the weft through the shed.

  • During this phase, the weft tensioner (3) and adjustable weft brake (4) minimize strain on the thread during picking.

d. Projectile (1) is stopped and pushed back inside the receiving unit.

  • Simultaneously, the weft tensioner (3) holds the thread lightly stretched, and the feeder (2) moves close to the cloth’s edge.

e. Feeder (2) grips the thread, and selvedge grippers (5) secure the weft.

  • The feeder grips the thread, while the selvedge grippers hold the weft at both sides of the cloth.

f. Weft is severed by the scissor (6) on the picking side.

  • The projectile on the receiving side releases the weft. The ejected projectile (1) is then placed on the conveyor to return to the picking position.

g. Reed beats up the thread. Tucking needles (7) secure weft ends into the next shed.

  • The reed beats up the thread, and tucking needles (7) tuck the weft ends into the next shed, creating a tucked-in selvedge. The length of thread slackened by the return of projectile feeder 2 is taken up by weft tensioner 3. The next projectile is brought to the picking position.

Torsion Bar Picking Mechanism:

Main Components:

  1. Cam Shaft
  2. Picking Cam
  3. Antifriction Roller
  4. Toggle Lever
  5. Pivot
  6. Torsion Rod
  7. Link
  8. Torsion Lever
  9. Picking Lever
  10. Picker
  11. Roller fixed to Cam-2
  12. Curved Contour of Toggle Lever-4
  13. Oil Brake

Mechanism Description:

  • This picking mechanism is exclusively used in projectile looms, and its success is crucial for the overall functionality of the loom.
  • The torsion rod is a pivotal component of this mechanism. It is twisted around a fixed position, with a maximum twisting angle of 30 degrees. This critical twisting action is achieved through the side-to-side movement of the toggle lever-4.
  • The torsion rod, made of alloy metal, serves as the primary element for the picking mechanism. Its twisted state influences the picking process.
  • The side-to-side movement of the toggle lever-4 is initiated by the cam pushing the antifriction roller. This movement is critical for the operation of the picking mechanism.
  • The roller fixed to cam-2 prevents the opposite movement of the toggle lever, ensuring controlled and precise action.
  • As the rollers (2) are released from the curved contour, the side-to-side movement of the toggle lever is freed, allowing the picking process to occur.
  • An oil brake is incorporated into the mechanism to prevent unlimited movement of the picking lever, adding control and stability to the process.
  • The picking force is directly influenced by the twisting of the torsion rod. This twisting action increases with the width of the loom and the coarseness of the weft yarn

Cam Beat-Up Mechanism in Projectile Loom:

Mechanism Description:

  • This mechanism explains how the weft yarn is released from the projectile guide during beat-up in a projectile loom.
  • As the projectile moves through the guide in unison with the weft yarn, the yarn lays into the guide.
  • Two antifriction rollers, namely antifriction roller-1 and antifriction roller-2, follow two cams. Antifriction roller-1 follows the outer profile of cam-1, and antifriction roller-2 follows cam-2.
  • The nose of cam-2 exerts pressure on antifriction roller-2 in the leftward direction. At a specific instant, the antifriction roller-2 moves downward due to the curvature portion of cam-2.
  • As a result of this movement, the sley (a part of the loom) shifts to the right, facilitating the release of the weft yarn from the guide through the slot in the guide.
  • Simultaneously, the reed (a comb-like component) beats up the newly inserted weft, ensuring it is firmly placed at the fell of the cloth.
  • It’s noteworthy that two cams are employed in this mechanism to limit the movement of the sley. The use of two cams enables a smooth beat-up achieved by the rotary motion of the cam, eliminating eccentric motion.

Advantages:

  1. Fashionable Applications:
    • Offers a wide range of applications.
    • Allows variation in fabric widths over broad limits.
  2. Reed Widths:
    • Accommodates reed widths from 33 cm for multi-width weaving.
    • Single widths can range from 220, 283, 334, 393, to 540 cm, depending on the machine type.
  3. Top-Quality Fabrics:
    • Weft and warp stop motions activate promptly and reliably.
    • Enables quick and traceless thread breakage, resulting in fabrics with fewer faults.
  4. Efficient Transport and Storage:
    • Rationalizes transport and storage to a significant extent.
  5. Mechanical Weaving Preparations:
    • Accepts common practices like drawing-in, pinning of drop wires, and knotting.
  6. Ease of Operation and Maintenance:
    • Simple to operate and maintain, reducing complexities.

Disadvantages:

  1. Skilled Personnel Requirement:
    • Requires skilled personnel for efficient operation.
  2. High Initial Investment:
    • Involves a substantial initial investment for acquisition.
  3. Durability Concerns:
    • Has a longer lifespan but may pose durability concerns over time.

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