Projectile Loom || Main Features of Projectile Loom || Different parts of Projectile Weaving Machine || Working Principle of Projectile Weaving Machine

Projectile Loom || Main Features of Projectile Loom || Different parts of Projectile Weaving Machine || Working Principle of Projectile Weaving Machine

Projectile Loom:

Sulzer brothers, Winterthur, Switzerland, the pioneer in the field of projectile method of weft
insertion. It is introduced in the market in 1953.The main feature of this machine is weft
insertion system. A bullet like shuttle 90 mm long & weighting about 40 g, technically named
as gripper projectile is used here to insert the weft thread into the warp threads.
This weaving machine is a shuttle-less 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. 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.




Main Features of Projectile Loom:

1. The picking are projectile receiving units are separated from the moving sley. The sley
carries the reed & gripper guides.
2. The gripper projectile made of fine steel, 90 mm long 14mm wide and 6 mm thickness
weight is 40 g. It carries the weft thread into the warp shed.

3. The weft is drawn directly from a large stationary cross wound package. There is no weft
winding.
4. The gripper projectile is picked across the warp shed at a very high speed ,the picking
energy being derived from the energy stored in a metal torsion bar which is twisted at
predetermined amount of released to give the projectile a high rate of acceleration .
5. Picking always takes place from one side, but several projectiles are employed and all of
them return to the picking side by a conveyor chain located underneath the warp shed.
6. During its flight through the shed the projectile runs in a rake likes steel guides, so that
the warp threads are touched neither by the projectile nor weft thread.
7. Every pick is cut off at the picking side near the selvedge after weft insertion, leaving a
length about 15 mm from the edge. Similar length of weft also projects from the selvedge
on the receiving side.
8. The ends of weft thread projecting on both sides of the cloth are tucked into the next shed
by means of special tucking device and woven in with next pick, thus providing firm
selvedges.
9. The reed is not reciprocated as in a shuttle loom, but rocked about its axis by a pair of
cams.
10. The reed & projectile guides are stationary during pick insertion.
11. The sley which carries the reed & projectile guides is moved forward &
backward through a saddle carrying two follower bowls, which bear against the surface
of two matched cams.
12. A sley dwell of 25 degree at back centre enables the projectile to travel through the warp
shed without being unnecessary reciprocated by the sley.
13. Whenever the reed width is reduced for weaving a small width cloth from the standard
reed width, the projectile receiving unit is moved inward on the telescope shaft, to the
new selvedge position, and so the projectile travel distance is reduced.
14. Smaller shed opening because of the smaller size projectile. This might result in lower
warp breakage rate.
15. Weft insertion rate up to 900-1500 m/min is possible depending up to the width of the
weaving machine.
16. The colour changing mechanism is less complicated.
17. In case of weft breakage the take up beam & heald frames can be driven in reverse by a
pick finding mechanism.








Main parts of Projectile Weaving Machine:

Torsion bar A: As shown in figure below, 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.
Picking shaft B: The free end of the torsion bar is linked with the picking shaft through
spines.
Picking lever C: The picking lever is clamped on the picking shaft.
Picking shoe D: The picking lever carries the picking shoe at its top end.
Picking shaft lever E: It is a rigid part of the picking shaft.
Toggle plates F: The toggle plates centre at carry a roller G and connected to the
picking shaft lever E through a link H .They are covered at the bottom.
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 fig. It carries a roller R after the nose
part.
Oil break L: The shock of the picking is taken by the oil break.


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) centre 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 centre of the
toggle arrangement are 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 centre, 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 0.007s 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 hydraulic buffer the body and plunger of which are shown at (L).

Suggestions:

The main feature of projectile loom is inserting the weft thread by projection method. If the
fault from the machine can be reduced then it will have the more weaving speed.
Projectile Loom || Main Features of Projectile Loom || Different parts of Projectile Weaving Machine || Working Principle of Projectile Weaving Machine Projectile Loom || Main Features of Projectile Loom || Different parts of Projectile Weaving Machine || Working Principle of Projectile Weaving Machine Reviewed by Suraj Gupta on May 08, 2020 Rating: 5

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