The present invention discloses system and method to manufacture uniformly
coated fabric by measuring thickness of polymeric coatings on non-woven fabric
using measuring gauges and adjusting it as necessary. The fabric may be woven,
5 non-woven type made from plastic, or paper fabric or any underlying substrate
that can be applied with a polymer coating.
Background of Invention
Woven fabrics are produced for plurality of applications, including bulk
10 containers, commodities packaging bags, tarpaulins for roof sealing or for
protecting from rain or any kind of exposed areas to be protected. The containers
or protecting tarpaulins exhibit high strengths and flexibility for making them
suitable for packing as well protecting roofs or floors. However, uncoated woven
fabric always poses risk of material leakage or entry of moisture into packaged
15 food material. To reduce or eliminate leakage of material from packing, it has
been established that interior or exterior polymeric coating on flat or circular
woven fabric reduces chances of leakage by filing pores on woven fabric.
One such type of conventional polymeric coating on circular woven fabric is
20 already disclosed in the US patent document US4844958. Objective of this patent
is to achieve polymeric coating on tubular woven fabrics. While it refers to
coatings in general sense, it does not teach how to ensure and maintain uniformity
of polymeric coating on woven fabric.
25 As disclosed in prior art, polymeric blend is applied on woven fabric though
various techniques to provide better bonding, the requirement of film thickness is
determined by usage or application of produced product. Although increased film
thickness provides better protection to the material to be protected it increases
cost of coating and therefore never considered as cost effective solutions.
3
Typically, non-adjusted openings of extrusion die lips distribute non-uniform
polymeric coating on woven fabric which adds almost no value to product. On the
other hand, this produces inferior fabric which have uneven coating considered as
low quality product. Traditionally, operators adjust die lips opening manually
5 based on GSM measurement of sample pieces taken across width of coated woven
fabric. This entire process of measurement and correction take significant time
which causes loss in production and importantly it is to be repeated for every
change in coated film thickness and material Recipe change.
10 Further, example of measurement of the thickness material layer is disclosed in
U.S. patent US 2020/0240776A1 (‘776A1) which describes system and method
embodiment for measuring a thickness of material layer using electromagnetic
radiation. In some embodiment, a system includes a radiation source configured to
direct first radiation towards a first surface of a layer of material having a
15 thickness between the first surface and a second surface opposite the first surface.
The first radiation causes the material layer to emit secondary radiation. A filter is
positioned between the material layer and a radiation in order to attenuate a
portion of the second radiation associated with fluorescence of the material to
emit third radiation. Then, the radiation detector is configured to provide a
20 measurement corresponding to the thickness of the material layer based on the
detected third radiation. It is evident from the figure 1A, 1B & 1C that invention
(‘776A1) only refers to the measurement of the thickness of material layer.
Further, invention (‘776A1) does not disclose anything about how the single/
double side coating thickness on a fabric is measured.
25
Therefore there is a need to disclose a method of manufacturing a coated fabric
with uniform thickness of coating wherein the coating thickness is measured and
adjusted as necessary as a part of the manufacturing process.
30
4
Objects of Invention:
One of the objects of the invention is to provide a system to manufacture a coated
fabric of uniform coating thickness by measuring thickness of polymeric coating
5 applied to a fabric as a part of the manufacturing process.
Another object of the invention is to provide a system of adjusting the thickness of
the polymeric coating applied to a fabric.
10 Yet another object of the invention is to provide a system whereby the thickness
of the polymeric coating applied to a fabric is uniform.
Another object of the invention is to provide closed loop system to adjust
extrusion die openings according to film thickness distribution.
15
A further object of the invention is to provide a method of measuring and
adjusting the thickness of polymeric coatings applied to woven or non-woven
fabrics.
20 Yet another object of the invention is to provide a method of applying polymeric
coating to a fabric whereby the thickness of the coated fabric is uniform
Brief Description of Figures:
Figure 1 illustrates complete fabric path movements from the unwinding section
25 to rewinding section.
Figure 2a illustrates top view of Gauge-1 measurement configuration
Figure 2b illustrates sectional view of uncoated fabric and relative locations of
30 gauges w.r.t the extrusion die
5
Figure 2c illustrates sectional view of one side coated fabric and the coating
distribution on one side coated fabric
5 Figure 3 illustrates the scanning pattern of Gauge-1 on uncoated and one side
coated woven fabric
Figure 4 illustrates top and side view of Gauge-2 measurement configuration
10 Figure 5 illustrates Scanning pattern of Gauge-2 on both sides coated woven
fabric
Figure 6 illustrates Auto Die closed loop control system
15 Figure 7 illustrates correspondence between first profile scan (15) & second
profile scan (16) of Gauge-1
Figure 8 illustrates correspondence between first profile scan (15), second profile
scan (16) & third profile scan (17) by Gauge-2
20
Figure 9 illustrates mapping of scanning profiles w.r.t extrusion die
Figure 10 illustrates mapping of scanning profiles w.r.t extrusion die for wide
width woven fabric
25
List of Parts:
1. Uncoated fabric
2. One side coated fabric
3. Both sides coated fabric
6
4. First coating layer of polymeric material; 4a – second coating layer of
polymeric material
5. Gauge-1
5a Gauge-1 radiating unit or device
5 5b Gauge-1 receiving unit or device
6. Gauge -2
6a Gauge-2 radiating unit or device
6b Gauge-2 receiving unit or device
7. Input roller
10 8. Upstream feed or guide roller
8a Turn-bar guide roller
8b Downstream guide roller
9. Extrusion device
10. Output roller
15 11. Gauge-1 home position
12. Gauge-1 limit position
13. Gauge-2 home position
14. Gauge-2 limit position
15. First scanning profile
20 16. Second scanning profile
17. Third fabric scanning profile
18. Extrusion die; 18a Die bolts
19. Gauges data processing & acquisition system
20. Auto die controls
25 21. Auto die closed loop system
Summary of Invention:
The invention discloses an apparatus for manufacturing a uniformly coated fabric
by measuring and adjusting the thickness of polymeric coatings applied to fabrics
30 as a part of the manufacturing process. An uncoated fabric is applied with a first
7
coating on one side or face and a second coating on the other side or face. The
apparatus employs scanners for the purpose of measuring the thickness of
coatings. The scanners scan the thickness of the coatings and assesses whether
they fall within acceptable level of uniformity. If the uniformity of thickness is
5 outside the acceptable margin, the die bolt nozzles through which the polymeric
coating melt is applied on the fabric are adjusted automatically or manually to
apply coating material as may be necessary. Fabric may be coated on one or both
sides. The system of invention is capable of measuring and adjusting thickness of
coatings on one or both sides of the fabric as necessary. The method of measuring
10 and adjusting the thickness of polymeric coatings applied to fabric comprises the
steps of:
- scanning the uncoated fabric and measuring its thickness tuc, and
establishing a first scanning profile
- apply a coating material on one side of fabric through die bolt nozzle
15 - scanning the one-side-coated fabric and measuring its thickness tosc, and
establishing a second scanning profile,
- assessing the uniformity of the thickness of first coating,
- adjusting the die bolt settings so that the first coating has the required level
of uniformity,
20 - applying a coating to the uncoated side of the one-side-coated fabric
- scanning the two-sides-coated fabric and measuring its thickness tbsc, and
establishing a third scanning profile,
- and assessing the uniformity of the thickness of second coating,
- adjusting the die bolt settings so that the second coating has the required
25 level of uniformity.
The scanners of the system travel across the fabric in a direction perpendicular to
the direction of travel of the fabric. The thickness of the first and second coatings
is calculated as the difference between tosc and tuc, and tbsc and tosc, respectively. In
30 order to improve the accuracy of the measurement and consequently that of the
8
uniformity of the thickness distribution, the scanners of the apparatus scan the
moving fabric at specific profiles. In particular, the best accuracy is obtained if the
first, second, and the third scanning profiles overlap. In other words best accuracy
is achieved by ensuring that all three thickness measurements - tosc, tuc, and tbsc are
5 taken at same points along the scanning path of the scanners, the scanners
measure the thicknesses at same locations along the fabric.
Detailed Description of Invention:
The present invention discloses an apparatus and a method for manufacturing a
10 uniformly coated fabric by measuring and adjusting thickness of coatings applied
to woven fabric. The apparatus uses electromagnetic radiation for this purpose.
The arrangement includes a radiation source configured to direct radiation
towards woven material moving in between a radiating source unit and radiation
receiving unit. The invention is not only limited to radiating and receiving unit
15 placed face-to-face, the purpose of the invention can also be achieved by single
source device which have inbuilt or on same side radiating and detecting means or
any kind of arrangement meant for the purpose of thickness measurement which
must be capable to measure uncoated and coated fabric both. Also, while
electromagnetic radiation is preferred, any other type of signals and a method of
20 sending and receiving signals for this purpose can be used.
Figure 1 shows a schematic view of the system/apparatus of the invention. It
shows a system/apparatus of applying polymeric coating to both sides of a fabric.
The thickness of coatings is measured and adjustment to the desired coating
25 thickness depending on the deviation of the measured thickness from the required
thickness. It shows two gauges – gauge-1 (5) and gauge-2 (6), each having
radiating sources to calculate coating thickness mathematically by capturing
thickness of the fabric at various stages of coating at different locations. It shows
a system wherein incoming uncoated fabric is scanned whereby its thickness is
30 measured at points of scanning to establish the base thickness or the thickness of
9
the uncoated fabric. The system makes similar thickness measurements of fabric
with one side coated and fabric with both sides coated. The system aims to collect
the thickness measurement data at same points in order that there is good
correlation between the three sets of measurements so that ultimately the
5 measured thickness of the coating layers is accurate. The system also allows
adjustment – made on the basis of the deviation of the measured thickness from
the required thickness of the coating layers (4 and 4a) – to the polymer extrusion
equipment that actually lays coating layers (or the coating application equipment)
on the fabric so that the coating thickness is within the required limits and has the
10 required level of uniformity across the fabric. Typical coating application
equipment is in the form of an extrusion die (18) that has multiple die bolts (18A).
The system described in detail here uses two gauges for scanning and thickness
measurement. However, it is possible to use further gauges to improve the
15 accuracy of measurement and adjustment of the coating application equipment.
Purpose of taking measurements at different points is to determine how much
correction or adjustment is required to be made to individual extrusion die bolt in
order to maintain uniform coating thickness across the fabric width.
20
In the system described here (Figure 1), the first gauge or scanner and the
thickness measurement device - guage-1 (5) - is located just after the fabric
unwinding section and the second gauge – or scanner and the thickness
measurement device - gauge-2 (6) – is located after extrusion die (18).
25 Alternatively, gauge-2 may be located downstream of the output roller (10),
which rolls out coated fabric. As will be evident from the ensuing discussion that
follows, gauge-1 measures the base thickness, i.e. the thickness of the uncoated
fabric and also the thickness of fabric coated on one side or one-side-coated
fabric, and gauge-2 scans and measures thickness of the fabric that is coated on
30 both sides or two-sided-coated fabric (or both-sides-coated fabric).
10
For the purpose of this description, one-side-coated fabric (2) means a fabric
having a first layer of coating (4) applied to one side of the uncoated fabric (1).
Similarly, the both-sides-coated fabric (3) has the first layer of coating (4) and a
second layer of coating (4a) applied across width of uncoated fabric (1) on either
5 of its sides or faces.
Both gauges (5 and 6) carry out the scanning operation by moving orthogonally to
the direction of movement of fabric. The stretch over which the gauges travel
depends on the fabric width. Since gauge-1 scans both uncoated and one-side10 coated fabrics, and which travel alongside each other (see Figure 2-a), the stretch
over which gauge-1 travels is such that it spans two fabric widths. The
arrangement by which the uncoated fabric (1) and one-side-coated fabric (2) are
made to travel side-by-side will vary from equipment manufacturer to equipment
manufacturer and will be known to a person skilled in the art.
15
Top half of Figure 2a illustrates arrangement for measuring thickness of the
uncoated fabric (1). Figure 2b shows view along section ‘a’ taken in Figure 2a.
The double arrow indicated in Figure 2a next to gauge-1 (5) suggests that gauge-1
(5) moves across the width of the fabric (1) in a direction perpendicular to fabric
20 travel direction. Bottom half of Figure 2a shows the one-side-coated fabric (2)
which runs alongside the uncoated fabric (1), and which is also scanned by gauge1 (5) while measuring the thickness of the first coating layer (4). Figure 2c shows
view along section ‘b’ taken in Figure 2a.
25 One key aspect of the present invention is that gauge-1 (5) scans and measures the
thickness of uncoated fabric (1) and that of the first coating layer (4) of the oneside-coated fabric (2) at same points. This is achieved by carefully establishing
scanning profiles of two sets of scanning. For example, when gauge-1 scans the
uncoated fabric, it establishes a first scanning profile (15), whereby thickness data
30 is collected at a first predetermined number of discrete points of the fabric.
11
Another key aspect of the present invention is that the data collection points
correspond to the die bolts of the extrusion die. Further aspect of the present
invention is evident when first layer of coating (4) is applied to the uncoated
fabric (1) and the one-side-coated fabric (2) travels side-by-side to the uncoated
5 fabric (1) and approaches gauge-1 (5) for getting scanned. According to an
embodiment of the invention, the points at which gauge-1 collects thickness data
on the one-side coated fabric and thus establishes a second scanning profile (16)
which correspond as exactly as possible to the specific points of the first scanning
profile. This is illustrated in Figure 7.
10
Figure 3 shows first and second scanning profiles (15, 16) carried out using
gauge-1. It shows two strips – one of the uncoated fabric (1) and the other being a
one-side-coated fabric (2) – traveling under guage-1. During scanning of uncoated
fabric (1), gauge-1 (5) moves from its home position (11) to its limit position (12)
15 following the first scanning profile (15). During the scanning operation, gauge-1
(5) measures thickness of the uncoated fabric (1) at the first predetermined
number of discrete points. In one aspect of the invention, the number and location
of the point of measurement of thickness along the first scanning profile (15)
correlate to the number of die bolts in the extrusion die (18) and their locations
20 along the extrusion die. This correspondence is schematically shown in Figure 9.
Gauge-1 starts its travel across the uncoated fabric (1) from the home position
(11) and follows a predetermined first scanning profile (15). Once it scans the full
width of the uncoated fabric (1) it stops the scanning activity and continues its
25 travel towards its limit position 12. Once it reaches the limit position (12), it
awaits the one-side-coated fabric to arrive. The uncoated fabric after having
undergone the first scanning profile (15) undergoes the coating stage whereby it is
converted into the one-side-coated fabric (2), which in turn undergoes the
scanning process under gauge-1 (5). Gauge-1 (5), which is stationary at the limit
30 position (12), starts its reverse journey so as to scan the one-side-coated fabric (2).
12
In a key aspect of the invention, the second predetermined number of discrete
points at which gauge-1 measures thickness of the one-side-coated fabric (2) to
establish the second scanning profile (16) corresponds to the points at which
gauge-1 (5) had measured the thickness of the uncoated fabric (1). Thus there is a
5 correspondence between the points of thickness measurements along first and
second scanning profiles (15, 16) – see Figure 7. Basically, start of gauge-1 to
follow profile (15) is taken as master and other profile scannings are slave
motions.
10 As the uncoated fabric (1) unrolls continually, gauge-1 (5) keeps scanning it at
predetermined intervals that are dependent on the speed of the coating apparatus.
For, each of the first scanning profile (15), there is a corresponding second
scanning profile (16), whereby the thickness of uncoated and one-side-coated
fabrics (1, 2) are measured for the progressing fabric.
15
The one-side coated fabric (2), having undergone the second scanning profile
(16), is subjected to the second layer of coating (4a) on the remaining uncoated
side of the original uncoated fabric (1), thereby converting it into the both-sidescoated fabric (3). The uncoated fabric (1) now has both its sides coated (see
20 Figures 2C and Figure 4). In a further aspect of the invention, thickness of the
second layer of coating (4a) is also measured and adjusted to the desired level by
making adjustments of the die bolt nozzles.
Figures 4 and 5 show a further aspect of the invention, where the thickness of the
25 both-sides-coated fabric (3) is measured. The Top View shown in Figure 4 shows
fabric (2) is going through the extrusion die (18) whereby a second layer of
coating (4a) is applied to the one-side-coated fabric (2) so as to form both-sidescoated fabric (3), which is also shown in the Side View of Figure 4. The bothsides-coated fabric (3) approaches gauge-2 (6) comprising a gauge-2 radiating
30 unit (6A) and gauge-2 receiving unit (6B). A further key aspect of the invention is
13
that gauge-2 (6) scans the both-sides-coated fabric (3) and measures its thickness
preferably exactly at the same points as gauge-1 (5) had measured during its first
and second scanning profiles (15, 16). In doing so, a thirst scanning profile (17) is
established. There is thus a correspondence (see Figure 8) between the points of
5 thickness measurements along first, second, and third scanning profiles (15, 16,
and 17).
The fabric thickness is measured at each of the scanning points which are mapped
to die bolts positions. For instance, in the preferred embodiment, if there are ‘n’
10 number of die bolts in extrusion die (18) then there would be ‘n’ number of
thickness measurement sampling points also. However, in other embodiments, the
number of die bolts can be more or less as compared to the number of points at
which the first and/or second and/or third scanning profiles have been established.
15 As shown in Figure 2b, the first layer of coating (4) is applied on side 1 of the
uncoated fabric (1). The thickness of the uncoated fabric (1) is denoted as tuc. As
we have seen earlier, the scanning points are preferably mapped to the positions of
die bolts. Assuming that there are m die bolts in the extrusion die (i.e. 1 to m), the
thickness of the uncoated fabric at m discrete points of measurement of the first
20 scanning profile (15) is denoted as tuc1, tuc2, tucm, etc. corresponding to the
positions of die bolt 1, die bolt 2, …die bolt m, respectively. Similarly, the
thickness of the one-side-coated fabric (2) is denoted as tosc1, tosc2, … toscm
corresponding to die bolt positions 1, 2, …m, respectively. In one embodiment,
the number of discrete points of measurement of first scanning profile (15) may
25 be different from the number of die bolts.
The thickness of the first layer of coating is calculated at all points of
measurement during the first and second scanning profiles (15, 16) as the
difference between thicknesses calculated during second scanning profile (15) and
30 first scanning profile (16). For example, at die bolt position 1, which corresponds
14
to a mapped point along the first and second scanning profiles, the thickness of
first layer of coating is (tosc1 - tuc1). In similar fashion, the thickness of the
polymer film coating (4) of a single-side-coating fabric (2) at any point along the
first (15) and second (16) scanning profiles will be calculated as the difference
5 between the thickness of the fabric coated on one sided minus the thickness of the
uncoated fabric: (toscm - tuc1), (tosc(m-1) - tuc2) ………(tosc1 - tucm), where 1, 2, …m
indicate the number of a die bolt which is mapped to points of measurements
along the scanning profiles.
10 In the case where the first predetermined number of points and the second
predetermined number of points is different, it is preferred that at least some of
these points overlap each other. In this case, the thickness of the first layer of
coating may be calculated as the difference between the measured thickness of the
uncoated fabric and the one-side-coated fabric at points of the first and second
15 scanning profiles (15, 16) that coincide with each other.
So, equation-1 for thickness of the first coating layer (4) at the location of die bolt
1, denoted as tfc1 measured by gauge-1 is as follows:
20
As described earlier, Figure 5 shows a third scanning profile (17) generated by
gauge-2 (6) for the both-sides-coated fabric (3). Scanning using gauge-2 (6) starts
25 from gauge-2 limit position (14) towards gauge-2 home position (13). In one key
aspect of the invention it is ensured that gauge-2 (6) scans the fabric (3) to collect
thickness data preferably at same points identified during first and second
scanning profiles (15, 16) resulting from scanning of the uncoated and one-sidecoated fabrics (1, 2). As described previously, all individual die bolts, i.e. die
30 bolts-1 to die bolts-m, are mapped to one-side-coated fabric (2) while the
Thickness mapped to Die bolt-1: (∆DieBolt1 ) = tfc1 = (toscm - tuc1)
15
individual die bolts from the (m+k) position to (n) are mapped to Side-2 of the
one-side-coated fabric (2) which are just overlapped to die bolt (m+k) to (n).
Here, ‘k’ is offset added to 'm' number of die bolts (18a) already mapped with uncoated fabric (1) for mapping with other side coating on one side coated fabric (2)
5 as shown in Figure 2a. As per process requirement, a person known to system can
set ‘k’ value from numeric ‘1’ onwards.
During scanning of both-sides-coated fabric (3) which is mapped to die bolt
position – m+k have tbsc(m+k) thickness and both-side-coated fabric (3) mapped to
10 die bolt position -‘n’ will have tbscn thickness. So, polymer film (4) thickness for a
double-side-coated fabric (3) which is mapped to die bolt position-(m+k) will be
(tbsc(m+k) - tosc1)). In similar fashion, polymer film (4) thickness which is mapped to
single side coating fabric will be calculated as (tbsc(m+1) - tosc1), … (tbscn - toscm).
15 Therefore equation-2 for thickness of the second coating layer (4a) at the location
of die bolt 1, denoted as tsc1 measured by gauge-2 is as follows:
20
In a further aspect of the invention, according to calculated differential values of
polymer film (4), either machine automation regulate die bolt settings (21) or
visually show it to operator for manual setting of die bolts to minimize or
eliminate thickness variation to maximum possible level.
25
The preceding description is one of the auto die measurement systems, as shown
in Figure 6, where the said system comprises of sensors i.e gauge-1 (5) and gauge2 (6) for converting physical signal into electrical data signal. Gauges data
processing & acquisition system (19) acquire continuous data from sensors,
30 process acquired data as per equations-1 & 2 for each die bolt mapping. Once
Thickness mapped to Die bolt-n: (∆DieBoltn ) = tsc1 = (tbscn - toscm)
16
deviation with respect to set coating thickness is known to system against each die
bolts, gauges data processing and acquisition system (19) generates commands for
auto die control (20) to adjust die bolts of extrusion die (18) to minimize error
between set and actual polymeric coating thickness.
5
As shown in Figure 2(b) & Figure 2(c), which shows side view of gauge-1 (5)
comprises a radiating unit (5a) and receiving unit (5b), respectively. They are
arranged such that to position each other face-to-face, as shown in Figure 2, one
acts as electromagnetic radiator and the other one acts as receiver. Similarly, as
10 shown in Figure 4, gauge-2 Radiating unit (6a) and gauge-2 receiving unit (6b)
face each other. Again, arrangement of gauge-1 (5) and gauge-2 (6) into their subunits being placed on the opposite sides of fabric is not necessary: there are
possibilities that better measurement configuration can be achieved by placing the
respective radiating and receiving units on the same side of the respective fabrics
15 or by using some kind of electromagnetic reflecting arrangement. Hence, present
invention can be accomplished by all kind of Gauging systems which can be used
to measure or estimate polymeric coating layer /film ‘4’ precisely which have
minimum possible measurement variations.
20 In an alternate embodiment, a person skilled in art can opt for uniform both side
coated fabric (3) thickness instead of maintaining uniform coating thickness on
each side of uncoated fabric (1). Here, all techniques of polymeric coating (4, 4a)
thickness measurement would be followed by applying same equations 1 & 2 as
described in earlier description. However, auto die closed loop system (21) will
25 adjust die bolts (18a) mapped from 1 to n such that sum of coated fabric (3)
thickness is constant throughout width of fabric. In this case, equation of total
coated fabric (3) thickness at any particular die bolt location would be as follows:
30
Coated fabric thickness: (∆const 1) = (tbscn - toscm) + ((toscm - tuc1) + tuc1)
17
In another alternate embodiment, apparatus as shown in figure 1 can be utilized
for single side coated product also by a person known to system. In this case,
gauge-1 would be employed to measure thickness of un-coated fabric and gauge-2
for measurement of one side coated fabric. Basically, this kind of application is
5 required in case of wide width fabric which cannot be operated parallelly as
shown in Figure 2a. Similar to method described for both side coated fabric, here
die bolts will be mapped uniformly from 1 to n as shown in Figure 10. Equation 1
will be followed to adjust die bolts setting as done earlier in case of both side
coated fabric.
10
Coating thickness is measured from set value in process. So, if set value is 25
micron and achieved thickness is 25 micron then it is defined as accurate or in
other words more close the actual value w.r.t set value it is called as better.
15 Empirically, Synchronization of scanning profiles at three measurement instances
is proven to be known better solution, however, not only limited to this
measurement technique. It is become apparent to those skilled in the art that any
modifications or change covering disclosures are understood as being included in
scope of the invention.

We claim:

1. A system to manufacture uniformly coated fabric by measuring and adjusting
thickness of coatings applied to an uncoated fabric (1) in an automated fabric
coating line to convert said uncoated fabric (1) first into a one-side coated
5 fabric (2) and then a both-sides-coated fabric (3), characterised in that said
system comprises a set of scanning and thickness measuring gauges, a
thickness data acquisition and processing unit, and an auto-die-control unit to
automatically adjust die bolts used for applying coating layers to said,
wherein
10 - said set of scanning and thickness measurement gauges consist of at
least two gauges, namely gauge-1 (5) and gauge-2 (6),
- said gauge-1 being capable of measuring at a first predetermined
number of discrete points the thickness of uncoated fabric (1) along a
first scanning profile (15) across the width of said uncoated fabric (1),
15 and measuring at a second predetermined number of points the
thickness of the one-side-coated fabric (2) along a second scanning
profile (16) across the width of said one-side-coated fabric (2),
- said gauge-2 being capable of measuring at a second predetermined
number of discrete points along a third scanning profile (17) across the
20 width of said both-sides-coated fabric (3) the thickness of said bothsides-coated fabric (3),
- said data acquisition and processing unit being capable of calculating
thickness tfc of a first coating layer (4) of said one-side coating as the
difference between the measured thickness at points along said second
25 and first scanning profiles (16, 15), and calculating the amount of
variation in tfc at the measured points,
- said data acquisition and processing unit being capable of calculating
thickness tsc of a second coating layer (4a) of said both-sides-coated
fabric (3) as the as the difference between the measured thickness at
19
points along said third and said second scanning profiles (17, 16), and
calculating the amount of variation in tsc at the measured points,
- said auto-die control unit being capable, on the basis of the assessed
variation in tfc and tsc, of automatically adjusting the nozzles of said die
5 bolts to regulate the amount of polymer extruded from said die bolts so
as to produce said first coating layer (4) and said second coating layer
(3) of uniform thickness.
2. The system as claimed in claim 1, wherein said each of said discrete points of
measurement along said first scanning profile (15) coincides with a
10 corresponding discrete point along said second scanning profile (16).
3. The system as claimed in claims 1 and 2, wherein said each of said discrete
points of measurement along said third scanning profile (17) coincides with a
corresponding discrete point along said first and second scanning profiles (15,
16).
15 4. The system as claimed in claims 1 and 2, wherein said uncoated fabric (1) and
said one-side-coated fabric (2) travel side-by-side.
5. The system as claimed in claims 1 to 4, wherein said gauge-1 has a gauge-1
radiating unit (5a) and a gauge-1 receiving unit (5b) which may be placed on
different sides of fabrics (1 or 2), and wherein said gauge-2 has a gauge-2
20 radiating unit (6a) and a gauge-2 receiving unit (6b) which may be placed on
different sides of fabrics (1 or 2).
6. The system as claimed in claim 5, wherein said gauge-1 comprises a single
unit with built-in radiating unit and a receiving unit, such that sending of
radiating signal and receiving it is carried out on the same side of the fabric (1
25 or 2).
7. The system as claimed in claim 5 and 6, wherein gauge-2 comprises a single
unit with built-in radiating unit and a receiving unit, such that sending of
radiating signal and receiving it is carried out on the same side of the fabric
(3).
20
8. The system as claimed in claims 5 to 7, wherein said radiation is
electromagnetic.
9. The system as claimed in claims 5 to 7, wherein said radiation is selected
from a group comprising ultrasonic, laser, capacitive.
5 10. The system as claimed in claims 1 to 9, wherein said first, second and third
predetermined number of points is same.
11. The system as claimed in claim 1, wherein said data acquisition and
processing unit being capable of calculating thickness tfc of a first coating
layer (4) thickness tsc of a second coating layer (4a) of said both-sides-coated
10 fabric (3) as the as the difference between the measured thickness at points
along said third and said second scanning profiles (17, 16), said auto-die
control unit being capable of automatically adjusting the nozzles of said die
bolts to regulate the amount of polymer extruded from said die bolts so as to
produce said first coating layer (4) and said second coating layer (3) of
15 uniform thickness.
12. A method of manufacturing coated fabrics by measuring and adjusting
thickness of coatings applied to an uncoated fabric (1) in an automated fabric
coating line to convert said uncoated fabric (1) first into a one-side coated
fabric (2) and then a both-sides-coated fabric (3) using the system as claimed
20 in claims 1 to 9, characterised in that said method comprises the steps of:
a. scanning an uncoated fabric (1) and measuring its thickness tuc at a first
predetermined number of points and establishing a first scanning
profile (15)
b. applying coating to one side of said uncoated fabric (1)
25 c. scanning the one-side-coated fabric and measuring its thickness tosc at a
second predetermined number of points and establishing a second
scanning profile (16),
d. determining the thickness of the first coating layer (4) at individual
measuring points as the difference between tocs and tuc at said first
30 predetermined discrete points
21
e. assessing the variation of the thickness of said first coating layer (4) on
the basis of the measured thickness of step d,
f. adjusting the die bolt settings to vary the amount of coating polymer
coming out of the die bolt nozzles on the basis of the measured
5 thickness variation of step e so that the thickness tfc of first coating
layer (4) of the one-side-coated fabric (2) has the required level of
uniformity,
g. applying coating to the uncoated side of one-side-coated fabric (2)
h. scanning the two-sides-coated fabric (3) and measuring its thickness
10 tbsc at discrete points and establishing a third scanning profile,
i. determining the thickness tsc of the second coating layer (4a) at
individual measuring points as the difference between tbsc and tosc at
said first predetermined discrete points,
j. assessing the variation of the thickness of said second coating layer
15 (4a) on the basis of the measured thickness of step i,
k. adjusting the die bolt settings to vary the amount of coating polymer
coming out of the die bolt nozzles on the basis of the measured
thickness variation of step j so that the second coating layer (4a) of the
both-sides-coated fabric (3) has the required level of uniformity.
20 13. The method as claimed in claim 12, wherein said each of said discrete
points of measurement along said first scanning profile (15) coincides with
a corresponding discrete point along said second scanning profile (16), and
wherein said each of said discrete points of measurement along said third
scanning profile (17) coincides with a corresponding discrete point along
25 said first and second scanning profiles (15, 16).
14. The method as claimed in claims 12 and 13, wherein said gauge-1 has a
gauge-1 radiating unit (5a) and a gauge-1 receiving unit (5b) which may
be placed on different sides of fabrics (1 or 2), and wherein said gauge-2
has a gauge-2 radiating unit (6a) and a gauge-2 receiving unit (6b) which
30 may be placed on different sides of fabrics (1 or 2).
22
15. The method as claimed in claims 12 to 14, wherein said gauge-1
comprises a single unit with built-in radiating unit and a receiving unit,
such that sending and receiving of radiating signal is carried out on the
same side of the fabric (1 or 2), and wherein said gauge-2 comprises a
5 single unit with built-in radiating unit and a receiving unit, such that
sending and receiving of radiating signals is carried out on the same side
of the fabric (3).
16. The method as claimed in claims 12 to 15, wherein said radiation is
electromagnetic.
10 17. The method as claimed in claims 12 to 16, wherein said radiation is
selected from a group comprising ultrasonic, laser, capacitive
18. The method as claimed in claims 12 to 17, wherein said first, second and
third predetermined number of points is same.
19. The method as claimed in claim 12, wherein adjusting the die bolt settings
15 to vary the amount of coating polymer coming out of the die bolt nozzles
on the basis of the measured thickness variation of steps e and j, so that the
one-side-coated fabric (2) of step e, and the both-sides-coated fabric (3) of
step i have the required level of uniformity in the thickness of respective
coated fabrics (2, 3).
20 20. A two-sided-coated fabric (3) characterised in that said fabric (3) is
manufactured using the apparatus as claimed in claims 1 to 11 and the
method as claimed in claims 12 to 19, wherein thickness of coatings is
uniform.