Shed Geometry

Topics: Weaving, Textile, Yarn Pages: 6 (1073 words) Published: August 23, 2013
Submitted by
PARTH PARMAR (120280725003)

In fulfillment for the award of the degree

May, 2013

DATE: 21/5/2013

This is to certify that the dissertation entitled :

"Geometry Of Warp Shed "
has been carried out by PARTH PARMAR under my guidance in fulfillment of the Degree of Master of Engineering in Textile Engineering (2nd Semester) of Gujarat Technological University, Ahmedabad during the academic year 2013-14.

Guided By:

PROF. A. I . THAKKAR Head of the Department


Shed Geometry & Different Possible Shed Geometries.
Elements Of Shed Geometry.
Shed Geometry Classification:-
"Shed Symmetricity
"Shed Vibration
"Shed Staggering
"Shed Clearance
Its Characteristics, Effect & Applications.

On a weaving loom, warp yarn are divided into two half to make up a shed. This division makes up a specific geometry of divided warp yarns, called "Shed Geometry".

Shed Geometry plays vital roll in controlling warp yarns, "Tension
"Elongation and
"Friction between them.

Resultantly this helps in controlling,
"Weft Density of Fabric
"Warp and weft yarn breakages and loom stoppages, hence machine efficiency "And also help to control/avoid fabric faults produced due to these.

"Different Possible Shed Geometries:

"Elements Of Shed Geometry:
Components that may part of the Shed Geometry of may contribute to it are: "Frame Height
"Frame Depth
"Cloth Support (front rest) Height
"Back Rest (and Deflecting Roller) Height and Depth
"Virtual Shed Dividing Line
"Dropper Box adjustment and droppers movement.

"Frame Height:-
It is the distance between two reference points, one is fixed and is on loom's stationary structure and other is on heald frame, as advised by the loom manufacturer. ᄁIt is usually measured when all the frames at same level i.e. at machine leveling position.

"Frame Depth (Lever Height):
It is distance between the a frames maximum height position to its lowest height position. ᄁAs it is adjusted by fixing lever joint on shedding system lifting levers, sometimes also said as Lever height.

"Cloth Support (Front Rest):
It is the most forward part of loom frame structure that is closest to the reed when it beats up and it is exactly beneath the cloth fell. It supports the fabric stay above as just filling is inserted into warp shed. ᄁIts height directly and most intensively effects the Shed Shape and Shed Geometry. ᄁ

"Back Rest (Deflecting Roller):
It is the rear most roller from where warp yarns start making the warp shed. ᄁIt is most frequently used element of the shed geometry to control and divide the warp tension, hence the pick density of the fabric being produced.

"Virtual Shed Dividing Line:
It is a line that divides the shed made at frames equally and is parallel to the machine horizontal.

Types of Symmetric Sheds:

"Symmetric Shed:

Whip roller height almost zero.
Cloth support and whip roller are at same height with respect to each other. "Application:
For Very light fabric such as voile, gauze i.e. fabric design in which longer float of warp and weft with almost 50% warp and 50% weft is apparent on both sides of the fabric with low fabric cover factor. ᄁYarns with little or no elongation.

Very weak yarns.
Handkerchief fabrics....
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