Working Principle, Advantages and Disadvantages of Projectile Loom

Last Updated on 05/06/2021

Projectile Weaving Machine or Loom:
Projectile weaving machine is a shuttleless loom method for filling yarn insertion using a small metal device resembling a bullet in appearance with a clamp for gripping the yarn at one end, which is then propelled into and through the shed. Among the different types of modern looms, projectile loom is one of them. The projectile weaving machine was introduced to the market in 1952 by Sulzer as the first successful, shuttleless weaving machine. In this weaving machine the weft insertion is carried out by small clamp projectiles, which number depends on the weaving width and which with their grippers take out the weft yarn from big cross-wound bobbins and insert it into the shed always in the same direction.

projectile weaving machine
Figure-1: Projectile weaving machine

The unique principle of projectile filling insertion allows the insertion of practically any yarn: cotton, wool, mono- and multifilament yarns, polypropylene ribbon, and even hard fibers like jute and linen. This is because all yarns, fine or coarse, are securely gripped and inserted by the
projectile, resulting in a wide variety of fabrics, from simple staple goods through superior fashion cloth and from wide heavy industrial fabrics to complex jacquard cloths.

Main Parts of Projectile Weaving Machine:
Major parts of projectile loom are given below:

  1. Torsion bar A: As shown in figure-2 it has splinted ends as seen in the fig one end is secured firmly at the clamping flange with provision for adjusting twisting angle. The twisting length of the torsion is 721 mm. It is diameter is 15, 17 or 19 mm depending upon the model. Larger the diameter higher the initial projectile speed. The angular twisting of torsion bar at commencement of picking is 28-30O.
  2. Picking shaft B: The free end of the torsion bar is linked with the picking shaft through spines.
  3. Picking lever C: The picking lever is clamped on the picking shaft.
  4. Picking shoe D: The picking lever carries the picking shoe at its top end.
  5. Picking shaft lever E: It is a rigid part of the picking shaft.
  6. Toggle plates F: The toggle plates center at o carry a roller G and connected to the picking shaft lever E through a link H. They are covered at the bottom.
  7. Picking cam I: It is mounted on a shaft J and rotated by bevel wheels K once every pick. It rotates in the direction of the arrow shown in figure-2. It carries a roller R after the nose part.
  8. Oil break L: The shock of the picking is taken by the oil break.
Picking mechanism on projectile weaving machine.
Figure-2: Picking mechanism on projectile weaving machine.

Where,
A=Torsion bar ,
B=Picking shaft ,
C=Picking lever ,
D=Picking shoe ,
E=Picking shaft lever ,
F=Toggle plate ,
G=Antifriction bowl ,
H=Link ,
I=Picking cam ,
J=Shaft ,
K=Bevel wheels,
L=Oil brake ,
P=Projectile ,
R=Projectile guide.

Working Principle of Projectile Weaving Machine:
Weft is withdrawn from the package through a tension device, weft tensioner, shuttle feeder, scissor, and weft end gripper. The picking arm has released the projectile which is shown in the guide teeth at the mid-shed position. At the receiving side the weft end gripper is positioned to grip the weft after reception. The shuttle break is shown in its operating position with the shuttle returner ready to push the projectile to the release and tucking position. Illustrates the torsion bar picking system of the machine. Strain energy is developed in the bar and released in such a way as to transfer the maximum possible strain energy to the projectile before it separates from the picker shoe.

The torsion bar (A) has its splined ends rigidly constrained in an adjustable housing with provision for adjusting the maximum angle of twist and projectile initial velocity. The other end of the torsion rod is splined into the picking lever (C) which carries the picking shoe (D) at its extremity. The projectile (P) is illustrated in the shuttle lifter with the projectile spring opener. The bevel wheel (K) rotates the picking cam shaft (J) which carries the picking cam (I). The picking shaft lever (E) is rigidly connected to the torsion bar and through a short linkage to the toggle plate (F) center at anti friction bowl (G). The action of the cam is for the small roller to bear against the toggle rotate it anti clockwise about anti friction bowl (G), thus withdrawing the picking shoe to its rearmost position. In this position the center of the toggle arrangement is in line and the torsion bar is twisted to its predetermined angle.

The nose of the picking cam then bears against the roller carried between the toggle plates and moves the central pivot of the toggle system off line center, thus permitting the strain energy in the rod to be transmitted instantaneously to the projectile. The projectile separates from the shoe after 6.4 cm travel in 0.007 s as a velocity of about 24.4 m/s after being subjected to a maximum acceleration of about 6700 m/s2 at a point 1.5 cm inboard of the rest position. The residual energy in the picking system, some 62% of the whole is absorbed in the hydrolic buffer the body and plunger of which are shown at (L).

Developments of Projectile Weaving Machine:

1. Color selection

  • 1 X 1, 2, 4 and 6 colors can be used in weft direction.
  • The system is freely programmable and operated by servo controller.
  • No limitations on feeder position shifting.

2. Electronic weft breaker

  • This device keeps a uniform tension on weft.
  • The braking force and the braking duration are programmable.
  • Programme can be given for each pick.
  • The device is driven by stepper motor.
  • Pre-acceleration to weft yarn is given by compressed air, which relieves extra tension in weft while inserting.
  • K3 Synthetic projectile can be used for weaving of delicate yarns.
  • The number of heald shafts operable by cam motion is extended to 14.
  • Speed has been increased up to 1400 mpm (470 rpm) due to improvement in many related mechanisms.
  • LED display at signal pole for machine speed, projectile arrival time, angle of machine stop, etc., which helps in monitoring of process.
  • Automatic weft brake repair motion enables shifting of feed package to a reserved one in the event of weft break between package and accumulator, no stopping of machine which increases the machine efficiency.

Advantages of Projectile Weaving Machine:
The projectile weaving machines offer the following advantages:

  1. Low power consumption
  2. Reduced waste of filling material due to unique clean, tucked-in selvages
  3. Quick warp and style change
  4. Mechanical and operational reliability and ease of use
  5. Low spare parts requirement and easy maintenance
  6. Long machine life

Another major advantage of projectile weaving machine is that more than one width of fabric can be woven at a time. Different widths, from 33 cm to 540 cm, make the projectile weaving machine even more economic, saving energy and space. Yet, because of the favorable speed at such weaving widths, wear and tear on the machine are also much reduced. Projectile weaving machines can be a single color or multicolor machine for any sequence of up to four or six different filling yarns.

Disadvantages of Projectile Loom:

  • High initial investment.
  • Skilled personnel needed for initial setup.
  • Noisier, compared to jet and rapier loom.

You may also like:

  1. Different Types of Modern Loom | Advantages of Modern Loom Over Conventional Loom
  2. Motions of Loom and Their Functions in Weaving Machine
  3. Basic Parts of a Weaving Loom and Their Functions
  4. Different Types of Shedding Mechanism in Weaving Process
  5. Automation in Weaving Machines: Process, Benefits and Requirements
  6. Production Calculation of Loom with Formula and Examples
  7. Essential Parts which are Used in Weft Insertion Motion of Loom

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