Main parts of Projectile Weaving Machine
1. Torsion bar A: As shown in fig 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 fig. It carries a roller R after the nose part.
8. 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.
Fig: Picking mechanism on projectile weaving machine.
Weft is withdrawn from the package through a tension device, weft tensionar, shuttle feeder, scissor, and weft end gripper.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 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 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 about24.4 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).