Projectile Weaving Machine or Loom

The projectile loom is a type of shuttleless weaving machine that uses small metal projectiles to insert the weft yarn into the warp shed. These projectiles, which are shaped like small bullets, are equipped with clamps that grip the weft yarn and propel it through the shed, completing the weft insertion.

Features of Projectile Loom for Weaving Techniques:

  • Projectile receiving units are typically separate components of the projectile loom, but they are closely integrated with the sley, which is responsible for carrying the reed and gripper guides. The gripper projectiles are then propelled through the warp shed by the projectile receiving units.
  • The gripper projectiles are typically made of a lightweight, durable material like carbon fiber, rather than steel, to minimize stress on the weaving machine and improve efficiency. However, some projectiles may have steel or other materials for specific applications.
  • The projectile guides are typically made of ceramic or other materials that are non-abrasive and non-damaging to the warp threads, and they are designed to guide the projectile through the shed without touching the warp threads.
  • The picking energy for the projectile loom is typically derived from an electric motor or other power source, rather than a metal torsion bar. However, some older models of the projectile loom may still use a torsion bar for picking energy.
  • After the weft insertion, the excess weft thread is typically cut off near the selvedge by a cutter blade, rather than being left in place.
  • Color changing machinery for the projectile loom can be either simple or complex, depending on the specific application and design requirements.
  • The weft thread is typically wound onto a small, portable bobbin or pirn, rather than a large stationary package.
  • The reed and projectile guides remain stationary during the pick insertion, while the sley and gripper projectiles move back and forth through the warp shed.
  • The smaller size of the projectile may result in a smaller shed opening, but this can be compensated for by adjusting the weaving parameters and machine settings to optimize fabric quality and efficiency.

The important part of the projectile loom weft insertion system is given below:


Projectile:
Its length is 90 mm approximately. It has a 40 – 60 grams weight range. The body of the projectile is made of steel. The grippers are fitted inside it. A hole is made at the gripper side to open the gripper’s jaws as per the requirement with the help of a projectile opener. It is projected into a projectile guide at the speed of 28 – 30 feet per second. An actual picture of a projectile is given below.


Guide teeth and projectile guide:
The projectile guide is constructed by arranging many guide teeth in one straight line. These guide teeth are mounted on the sley in a straight line. Proper alignment of guide teeth is carried out with the help of an alignment gauge. The projectile travels through this projectile guide. Weft gets released in the projectile guide but during beating motion, the weft yarn comes out of the projectile guide through the open space( slot) present in each guide tooth.  A real picture of guide teeth is given below:

Conveyor chain ( projectile transport system):
The projectile is propelled in the loom from the picking side only. The number of projectiles being used on the loom depends upon the reed space used. These projectiles are transported from receiving side to the picking side with the help of a conveyor chain. It is a simplex chain. The projections are mounted on the conveyor chain at regular intervals of distance. There is 10 inches distance kept between two adjacent projections mounted on the chain. The projectile falls upon the travelling path and the conveyor chain moves over this travelling path. This conveyor chain rotates in the anti-clockwise direction. When rotating projection passes over the travelling path, it pushes the projectile and carries it to the projectile lifter.

Working Principle

  • The working principle of a projectile loom is based on the use of small metal or carbon fiber projectiles, which are propelled through the warp shed to insert the weft yarn. The projectiles are stored in a magazine at one end of the loom and are propelled through the shed by a series of guides and drives.
  • The projectile contains a gripper at one end that grabs the weft yarn as it is propelled across the width of the fabric. The projectile then returns to its starting position, leaving the weft yarn behind in the shed. The shed is then closed, and the fabric is beaten up with a reed to push the weft yarn firmly into place before the next projectile is propelled across the shed to insert the next weft yarn.
  • The weft yarn is wound onto a stationary cross-wound package, which is placed at one end of the loom. The reed, which is used to beat up the weft yarn, is not joined to the loom as it is in a shuttle loom. Instead, it is rocked about its axis by a pair of cams. The projectile guides and reed guides are stationary during the pick insertion.
  • The picking action in a projectile loom is accomplished through the use of energy stored in a metal torsion bar that is twisted for different looms. The projectile is propelled across the width of the fabric by the energy released as the torsion bar unwinds.

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