The present invention relates to the method and apparatus to measure fabric width
through tactile method.
5 BACKGROUND OF INVENTION
The circular weaving loom or machine (CWM) is designed to weave endless
tubular or flat fabric using PP, HDPE, LLDPE yarn/tape or other blends of
polyolefin.
10 The warp yarns/slit film tapes are fed to the weaving machine from more than one
creel via rollers. This ensures uniform warp tension, excellent fabric quality, and
trouble-free handling.
Another set of slit film tapes required during weaving are known as weft tapes
15 which get sourced from cylindrical bobbins arranged in shuttles, these shuttles are
moving around center axis of machine and parallelly unwinding tapes by rotating
around its center axis. Tension of unwinding tapes from weft bobbins varies as
diameter of bobbin changes during unwinding process. Practically, it has been
observed that tape tension increases as diameter of bobbin reduces during the
20 unwinding process. Accumulated result of individual tape tension variation causes
change in fabric width, which causes difficulties in downstream processes that use
the fabric to make articles from it.
There are various prior arts available that disclose different types of edge
25 detection systems. Some of the relevant prior arts to current invention are
referenced in US5220177 and US6201604.
However, the non-contact type apparatuses, such as those disclosed in the
aforementioned US patents result in non-accurate measurement on circular loom
30 type machines, if environmental conditions like light, accumulation of dust etc.
3
around measuring instrument are not favorable. Further, such apparatuses are
costly and require skilled manpower for setting and operation.
Therefore, there a need for a low cost apparatus for accurately and continuously
5 measuring the width of fabric manufactured on a circular loom. The present
invention provides for such low-cost effective solution based on tactile sensing.
OBJECTS OF INVENTION
It is an object of the present invention to provide a simple and low cost tactical
10 apparatus to measure width of moving fabric accurately.
Another aspect of the present invention is to design a simple, maintainable &
scalable apparatus.
15 Yet another objective of the present invention is to design an independent
workable apparatus which can be integrated with any weaving machine or any
other machine where current invention can be used.
Another objective of the present invention is to continuously monitor and
20 communicate measured fabric width on running loom.
Another objective of the present invention is to provide quantified data for
classifying the produced fabric roll quality on width variation criteria.
25 SUMMARY OF INVENTION
There are many methods and apparatus available to measure width by locating
edges of fabric through optical instruments like array of light emitting diodes or
imaging system, but present invention discloses a unique method and apparatus
arrangement to locate edges through tactical method.
30
4
Unlike any edge tracking system which is based on complex optical concept,
present invention discloses a simple mechanical arrangement which can be
configured according to width of underlying moving fabric such that both edges
of fabric are touched by arms which have angular deflection measuring device
5 mounted on them. Angular deflection measuring devices are mounted on arms
such that rotational axis of arms aligns with center axis of them. Deflection of
these arms with respect to reference line is read through an angular deflection
measuring device electrical output to determine angle of deflection with respect to
reference axis which is considered vertical here for easy explanation. A simple
10 linear trigonometric equation can be used to calculate fabric width by knowing
angels of deflecting arms.
The apparatus of the invention is a simple tactical system to measure width of
moving fabric accurately. It comprises a pair of angular position measuring
15 sensors, namely a first angular position measuring sensor and a second angular
position measuring sensor, each of which is supported by a corresponding
movable arm, namely a first moving arm and a second moving arm positioned at
respective angles θ1 and θ2 with the axis perpendicular to woven fabric surface
(which is normally vertical) and which touch the edges of the fabric. The angles
θ1 and θ2 are preferably less than 45o 20 . As the fabric width varies, the angular
position of the movable arms, which rest on the fabric edge, will also vary. The
variation in the angular position is sensed by the angular position measuring
sensors which also transmit the data to a computing module that calculates the
width of the fabric, thereby monitoring it.
25
BRIEF DESCRIPTION OF FIGURES
Figure 1 illustrates front view of complete apparatus
Figure 2a illustrates top view of apparatus without supporting rollers
Figure 2b illustrates top view of apparatus with supporting rollers
30 Figure 3a illustrates side view of apparatus without supporting rollers
5
Figure 3b illustrates side view of apparatus with supporting rollers
Figure 3c illustrates side view of apparatus with supporting rollers held by Frame
supporting rods
Figure 4 shows block diagram of an arrangement for gathering angular position
5 data and transmitting calculated values
Figure 5 shows location of placement of the apparatus of the invention
LIST OF PARTS
Supporting bar (1)
10 First angular position measuring sensor (2)
Second angular position measuring sensor (2a)
First moving Arm (3a) and second moving arm (3b)
Woven Fabric (4)
First supporting rollers (5a) second supporting roller (5b)
15 Computing Module (6)
Transmitting module (7)
Frame Supporting rods (8)

DETAIL DESCRIPTION OF INVENTION
20 The present invention discloses apparatus and a method for measuring width of
the fabric when it unrolls from a fabric roll. The device uses a set of mechanical
arms positioned angularly, which are in touch with the fabric edges as it travels.
Depending on the continued monitoring of the change in the angular position of
the mechanical arms, the fabric width is calculated on a continual basis.
25
As shown in Figure 1, the apparatus of the invention comprises a pair of angular
position measuring sensors, namely a first angular position measuring sensor (2)
and a second angular position measuring sensor (2a), each of which is supported
by a corresponding movable arm, namely a first moving arm (3a) and a second
30 moving arm (3b) positioned at respective angles θ1 and θ2 with the axis
6
perpendicular to woven fabric surface (which is normally vertical) and which
touch the edges of the fabric (4). The angles θ1 and θ2 are preferably less than 45o
.
The apparatus of the present invention is mounted as an independent unit on
5 circular weaving machines along the direction of produced woven fabric (4) but
its application is not limited to such machines only. The orientation of the
apparatus of the present invention would be set such that a supporting bar (1)
which is located above the moving fabric (4) holds the two moving arms (3a and
3b) at their top ends as shown in Figure 1.
10
The apparatus of the present invention may be mounted at any location after the
fabric has been woven but where it has adequate tension – for example before it
has been taken up for rewinding on bobbins to form fabric rolls.
15 The apparatus of the present invention provides flexibility of adjusting positions
of moving arms (3a and 3b) such that their locations can be adjusted based on
width of woven fabric (4). Another aspect of the invention is that it avoids turning
of edges due to weight of moving arms (3a and 3b). As shown in Figure-2(a)
which represent condition when fabric is moving without any support resulting
20 turning of woven fabric inwards due to weight of moving arms (3a and 3b) lying
on the edges of fabric and weight of fabric itself. Figure 2(b) shows two
supporting rollers or rods (5a and 5b), which provide extra support for
maintaining tightness at the edges for the portion of the fabric between the support
rods (5a and 5b).
25
As one key aspect of the invention, supporting rollers (5a and 5b) as shown in
Figure 3(b) will prevent fabric from sagging under its own weight which makes
fabric edges tighter than arrangement shown in Figure 3(a), where no such support
rods (5a and 5b) have been provided. The supporting rods (5a and 5b) are
30 positioned with respect to the holding bar (1) through frame supporting rods (8)
7
such that entire assembly can be fixed at desired location as indicated in Figure-5.
Pre-calibrated mechanical arrangement with frame supporting rods (8) also
eliminates possibility of variation in vertical distance ‘H1’ and ‘H2’ due to
mechanical inaccuracies in Loom machine assembly which is explained later in
5 text. For simplicity of figures, these frames supporting rods are only shown in
Figure 3c.
Aforementioned moving arms (3a and 3b) are coupled with respective angular
position measuring sensors (2, 2a). These angular positions measuring systems (2)
10 measure the angular positions of moving arms (3a and 3b). The angular position
measuring sensors (2, 2a) can be an encoder or a resolver or a proxy or any other
suitable device which can continuously or discretely measure the angular
movement of moving arm (3a and 3b) in terms of the angle θ. Angular position
means location of arms (3a, 3b) at any instance when it is rotated by some angle
15 from vertical position.
The present invention also consists of a unit responsible for computation of total
fabric width is known as a computing module (6). This module gathers angular
positions data from individual angular position measuring sensors (2, 2a) for
20 processing and calculating instantaneous value of woven fabric (4) width.
In the preferred embodiment, the computing module (6) calculates woven fabric
width based on various input parameters like measuring angle (θ1 and θ2),
positioning of moving arms represented by the distance between the ends points
25 of the two arms (L), distance (H) between moving fabric and the center of
mechanical holding bar (1) measured at the center of the holding bar (1). One
aspect of the preferred embodiment is to minimize error in measurement of
distance (H) through an ultrasonic or laser or inductive technology or any kind of
other sensor or mechanical arrangement which can accurately input distance
30 parameter to computing module automatically, or manually in case of a
8
mechanical arrangement. One easy method of estimating distance (H) manually
with sufficient accuracy is adjusting supporting rollers (5a and 5b) at known
distance from supporting bar (1).
5 There is also a possibility to mount distance sensors like ultrasonic or laser or
inductive at center axis of each angular position measuring sensors (2, 2a) to
measure vertical distance ‘H1’ & ‘H2’ to eliminate estimation error, if H ≠ H1 ≠
H2 in case of supporting bar is not exactly parallel to moving fabric due to
inaccuracies in the loom’s mechanical structure assembly. But to simplify
10 explanation, it is assumed that H = H1 = H2.
The following parameters are either measured or known:
H = Distance of fabric top from center of angular position measuring sensors (2,
2a)
15
(θ1 & θ2) = Angular positions of moving arms (3a and 3b) w.r.t perpendicular on
fabric surface
L = distance between centers of two angular position measuring sensors (2, 2a)
20
Based on these input parameters, the fabric width (W) at any point along the
fabric can be calculated accurately by using following calculation:

25
Where,
W = Calculated Fabric Width
H = Distance of fabric top from center of Angular position measuring sensors (2,
30 2a),
W = H{tan(θ1) + tan(θ2)} + L
9
If H1 is vertical distance of the fabric from device measuring angle ‘θ1’ & H2 is
vertical distance of the fabric from device measuring angle ‘θ2’, then in the case
H1 and H2 are equal, H=H1=H2.
5
In the case H1 and H2 are not equal, H is taken as the average of H1 and H2.
(θ1 & θ2) = Angular positions of moving arms (3a, 3b) w.r.t perpendicular on
Fabric surface
10
L = distance between centers of two angular position measuring sensors (2, 2a)
Another aspect of the present invention is the transmission of computed fabric
width (W) to a remote controller for processing. As shown in Figure 4, a
15 transmitting module receives computed information from the computing module
and transmits the information through wired or wireless medium to remote
receiving units. The operator of the loom may adjust tension of shuttles or he can
use invention as an inspection system.
20 As the fabric width varies, the angular position of the movable arms (3a, 3b),
which rest on the fabric edge, will also vary. The variation in the angular position
is sensed by the angular position measuring sensors (2, 2a) which also transmit
the data to the computing module that calculates the width of the fabric, thereby
monitoring it.
25
While using the device of the present invention, it can be isolated from loom
machine vibrations by providing dampeners as part of standalone systems. Figure
5 shows flow of tapes used to make woven tubular fabric on a circular loom and
the woven fabric emerging out from the circular weaving loom. It shows warp and
30 weft tapes released from bobbins and which ultimately form the fabric after
10
weaving. The fabric is pulled up from the loom and supplied to a roll on which it
is wound. As shown in Figure 5, the apparatus of the invention is positioned at a
point where the tubular or circular fabric is formed and flattened before taking up
for winding on a roll.
5
The present invention offers an accurate measurement system at much lower cost
in comparison to non-contact measurements offered through optical,
electromagnetic or any other known systems which have multiple times cost.
It is evident from the foregoing description that the invention has a number of
10 embodiments.
The invention also discloses a method of measuring width of a moving fabric (4)
using the apparatus disclosed in the foregoing disclosure. It comprises the steps
of:
15 - placing the pair of angular position measuring sensors (2, 2a) at the
predetermined distance (L) between them and at the predetermined
height (H1, H2, preferably H1 = H2) from the plane of said fabric (4),
each of which is rotatably attached to the supporting bar (1),
- providing a pair of moving arms (3a and 3b), that are rotatably
20 connected at their respective upper ends to said angular position
measuring sensors (2, 2a), and which are supported near their other end
by the edge of said fabric (4), whereby an angle (θ1 and θ1) is formed
moving arms (3a and 3b) with the vertical,
- positioning the pair of supporting rollers (5a, 5b) transversely across
25 the width of fabric (4), wherein said moving fabric (4) is supported
tautly by said supporting rollers (5a, 5b) which themselves are
positioned on either side of said supporting bar (1)
- calculating the width of said moving fabric (4) using the computing
module to calculate width of moving fabric (4) on the basis of data
30 collected by said angular position measuring sensors (2, 2a).
11
In an embodiment of the method of the invention, the computing module
computes the fabric width according to the following formula:
W = H * {tan(θ1) + tan(θ2)} + L
5
wherein H is adjusted like to achieve H=H1=H2, otherwise, equation to be
modified considering H1 & H2 as parameters.
In a further embodiment of the method of the invention, said angular position
10 measuring sensors (2, 2a) are an encoder or a resolver or a proxy or any other
suitable device that is capable of continuously or discretely measuring the angular
movement of said moving arm (3a and 3b) in terms of the corresponding angles
(θ1 and θ1).
15 In another embodiment of the method of the invention, said angles (θ1 and θ1) are
less than 45o
.
While the above description contains much specificity, these should not be
construed as limitation in the scope of the invention, but rather as an
20 exemplification of the preferred embodiments thereof. It must be realized that
modifications and variations are possible based on the disclosure given above
without departing from the spirit and scope of the invention. Accordingly, the
scope of the invention should be determined not by the embodiments illustrated,
but by the invention as a whole and in addition to appended claims and their legal
25 equivalents.

We claim:

1. An apparatus for measuring width of moving fabric (4) woven on a
circular loom, characterized in that said device comprises:
- a pair of angular position measuring sensors (2, 2a) placed at a
5 predetermined distance (L) between them and at a predetermined
height (H1, H2) from the plane of said fabric (4), each of which is
rotatably attached to a supporting bar (1),
- a pair of moving arms (3a and 3b), that are rotatably connected at their
respective upper ends to said angular position measuring sensors (2,
10 2a), and which are supported near their other end by the edge of said
fabric, whereby an angle (θ1 and θ2) is formed moving arms (3a and
3b) with the vertical,
- a pair of supporting rollers (5a, 5b) positioned transversely across the
width of fabric (4),
15 - a computing module to calculate width of moving fabric (4) on the
basis of data collected by said angular position measuring sensors (2,
2a),
wherein said moving fabric (4) is supported tautly by said supporting
rollers (5a, 5b) which themselves are positioned on either side of said
20 supporting bar (1).
2. The apparatus as claimed in claim 1, wherein said computing module
computes the fabric width according to the following formula:
W = H * {tan(θ1) + tan(θ2)} + L,
25
wherein H =H1=H2.
3. The apparatus as claimed in claims 1 and 2, wherein said angular position
measuring sensors (2, 2a) are an encoder or a resolver or a proxy or any
30 other suitable device that is capable of continuously or discretely
13
measuring the angular movement of said moving arm (3a and 3b) in terms
of the corresponding angles (θ1 and θ2).
4. The apparatus as claimed in claims 1 to 3, wherein said angles (θ1 and θ2)
are less than 45o 5 .
5. The apparatus as claimed in claims 2 to 4, wherein in the case H1 and H2
are not equal, H is taken as average of H1 and H2.
10 6. A method of measuring width of a moving fabric (4) using an apparatus as
claimed in claims 1 to 5, wherein said method comprises the steps of:
- placing the pair of angular position measuring sensors (2, 2a) at the
predetermined distance (L) between them and at the predetermined
height (H1, H2) from the plane of said fabric (4), each of which is
15 rotatably attached to the supporting bar (1),
- providing a pair of moving arms (3a and 3b), that are rotatably
connected at their respective upper ends to said angular position
measuring sensors (2, 2a), and which are supported near their other end
by the edge of said fabric (4), whereby an angle (θ1 and θ2) is formed
20 by moving arms (3a and 3b) with the vertical,
- positioning the pair of supporting rollers (5a, 5b) transversely across
the width of fabric (4), wherein said moving fabric (4) is supported
tautly by said supporting rollers (5a, 5b) which themselves are
positioned on either side of said supporting bar (1)
25 - calculating the width of said moving fabric (4) using the computing
module to calculate width of moving fabric (4) on the basis of data
collected by said angular position measuring sensors (2, 2a).
14
7. The method of measuring width of a moving fabric (4) as claimed in claim
6, wherein said computing module computes the fabric width according to
the following formula:
W = H * {tan(θ1) + tan(θ2)} + L, wherein H = H1 = H2.
5
8. The method of measuring width of a moving fabric (4) as claimed in
claims 6 and 7, wherein said angular position measuring sensors (2, 2a) are
an encoder or a resolver or a proxy or any other suitable device that is
capable of continuously or discretely measuring the angular movement of
10 said moving arm (3a and 3b) in terms of the corresponding angles (θ1 and
θ2).
9. The method of measuring width of a moving fabric (4) as claimed in
claims 6 to 8, wherein said angles (θ1 and θ2) are less than 45o
.
15
10. The method of measuring width of a moving fabric as claimed in claims 7
to 9, wherein in the case H1 and H2 are not equal, H is taken as average of
H1 and H2.