U.S. patent number 3,688,354 [Application Number 05/058,855] was granted by the patent office on 1972-09-05 for method of handling and processing open width fabric.
This patent grant is currently assigned to Samcoe Holding Corporation, Woodside, NY. Invention is credited to Andrew P. Cecere, Eugene Cohn, Robert Frezza.
United States Patent |
3,688,354 |
|
September 5, 1972 |
METHOD OF HANDLING AND PROCESSING OPEN WIDTH FABRIC
Abstract
The application is directed principally to a method of
processing open width fabrics, particularly distortable fabrics
such as those of knitted construction, in a rotary-type of tenter
processor in which the fabric is acted upon by high velocity air
streams. The fabric is first engaged by its opposed edge
extremities and distended to a predetermined width; it remains so
engaged throughout the processing operation. The thus engaged
fabric is supplied to and mechanically supported by a synchronously
rotating processing drum. Of significance, the fabric, regardless
of its width, is applied symmetrically to the center area of the
drum and held by its edges at a uniform width regardless of the
overall axial length of the drum, which may be considerably greater
than the width of a given fabric web. While the fabric is supported
on the drum, high velocity streams, extending over the full axial
length of the drum and independent of the width of the fabric, are
directed radially through the fabric and drum to effect the desired
processing. Exceptional uniformity of processing results is thus
achieved.
Inventors: |
Eugene Cohn (Great Neck,
NY), Andrew P. Cecere (Valley Stream, NY), Robert
Frezza (Carle Place, NY) |
Assignee: |
Samcoe Holding Corporation,
Woodside, NY (N/A)
|
Family
ID: |
22019306 |
Appl.
No.: |
05/058,855 |
Filed: |
July 28, 1970 |
Current U.S.
Class: |
26/52; 26/76;
26/90; 26/74; 26/86; 26/98; 34/454 |
Current CPC
Class: |
D06C
3/02 (20130101) |
Current International
Class: |
D06C
3/00 (20060101); D06C 3/02 (20060101); D06c
003/02 () |
Field of
Search: |
;26/57,57A,59,57E,60,61A,55WC ;34/23,112,122,158 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1567 |
|
Jan 1, 1899 |
|
GB3 |
|
7500 |
|
Jan 1, 1837 |
|
GB3 |
|
14097 |
|
Jan 1, 1852 |
|
GB3 |
|
Primary Examiner: Robert R. Mackey
Attorney, Agent or Firm: Mandeville and Schweitzer
Parent Case Text
RELATED APPLICATIONS
The present application is a division of our copending application
Ser. No. 698,899, filed Jan. 18, 1968, now U.S. Pat. No. 3,551,970
granted Jan. 5, 1971. The subject matter of the application is also
broadly related to the subject matter of the prior U.S. Pat. Nos.
3,065,551 and 3,102,006, issued to Samuel Cohn et al., and is
usefully employed in conjunction with the subject matter of the
Sidney L. Carter et al., U.S. Pat. No. 3,289,510.
Claims
We claim:
1. A method for processing tubular knitted fabrics of various
widths in a rotary tenter processor apparatus, the steps which
comprise a. slitting and opening a tubular knitted fabric; b.
engaging the slit and opened fabric by its opposed edges and while
continuously engaged, distending the fabric to a predetermined
width; c. passing said continuously engaged and distended fabric
through a pretreating zone for impinging said fabric with discrete
volumes of treating air; d. applying said continuously engaged and
distended fabric to, and mechanically supporting one surface of
said fabric by, a fixed width rotary processing drum; e. said
continuously engaged and distended fabric being applied without
interruption of the engagement and distention thereof symmetrically
to the center of the drum at its distended width independent of the
axial length of said drum; f. impinging the fabric surface with
radially directed high velocity streams of processing air from
stationary points closely adjacent the circumferential surface of
said drum through said continuously supported and distended fabric
and radially into said drum; g. said high velocity air streams
extending over the full axial length of the drum, independent of
the distended width of said continuously engaged and distended
fabric supported thereon, and h. removing said fabric from said
drum surface while still in its continuously engaged and distended
form and passing said fabric through a post-treating zone for
impinging said fabric with discrete volumes of treating air.
2. The method as recited in claim 1, in which said engaging step is
carried out by overfeeding said slit and opened fabric.
Description
BACKGROUND AND PRIOR ART
In the commercial manufacture and processing of knitted fabrics,
large quantities of such fabrics are manufactured on circular
knitting machines, which initially construct the fabric in tubular
form. To a large extent, such circular or tubular knitted fabrics
have been handled substantially throughout the entire processing
sequence in tubular form, and a variety of processing and handling
equipment is available, which accommodates the knitted fabric in
its tubular form. To an increasing extent, however, newer types and
styles of tubular knitted fabrics, and more demanding end use
specifications for such fabrics, are compelling the fabric
processor to process knitted fabric in open width form, even though
the fabric may have been initially constructed in tubular form. For
example, many modern fabrics, when passed through a processing nip
or otherwise subjected to pressure while in tubular form, will form
an edge crease, particularly when the fabric is in a wet condition.
With some fabrics, this creasing is an irreversible process in that
the crease mark cannot subsequently be completely removed.
Accordingly, it is becoming desirable to an increasing extent to
process many knitted fabrics by first slitting and opening the
fabric, before it is subjected to any processing steps involving
the application of pressure. Thereafter, the fabric is handled and
processed in flat, open width form, so that there is no occasion
for edge creases to be imparted to the fabric.
In the processing of woven goods, which typically are initially
constructed in flat form, it has long been the practice to handle
and process such fabrics in open width form. This being the case,
there are certain similarities between the open width processing of
knitted fabrics and woven fabrics. However, by reason of the unique
construction of the knitted fabric by interlocking loops, rather
than by interwoven warp yarns extending length wise and woof yarns
extending widthwise, the knitted fabric has an inherent
interdependence of length and width dimensions and an inherent
geometric instability. These characteristics of the knitted fabric
differ not only in degree but also in kind from the characteristics
of woven fabric, such that the equipment and technology long
available to the woven goods industry is not easily translatable to
the knit goods processing industry, accounting for the fact that
open width processing of knitted fabric now is practiced only in
limited volume relative to the processing of fabric in tubular
form.
The present invention concerns itself most significantly with the
processing, as by drying, heat setting, or curing of an open width
knitted fabric, and the handling of the fabric immediately prior to
and following such processing. However, many principles of the
invention are applicable to advantage in the processing of woven
fabrics and other web materials and the invention is not
necessarily limited to the processing of knitted fabrics. In the
new system, a unique rotary drum processor arrangement is provided,
which is capable of handling and processing open width knitted
fabric and other fabric webs with high efficiency and uniformity.
To this end, the processing unit incorporates a number of features
of significant novelty which render the apparatus commercially
useful and desirable for the specific application of drying, heat
setting or otherwise processing open width knitted fabric and other
porous web materials and distinguish it significantly from prior
art proposals for rotary tenter-type dryers, such as is reflected
by the previously issued Parkes U.S. Pat. No. 1,963,672, and the
Hunter et al., U.S. Pat. No. 2,252,181, for example.
SUMMARY OF INVENTION
In accordance with one aspect of the invention, a novel and
improved rotary drum tenter processor is provided, which is
specifically suitable for the drying or other processing of open
width fabric webs. The dryer of the invention incorporates a large
diameter processing drum, of open mesh construction, which is
surrounded very closely over much of its circumference by air
nozzles arranged to direct closely spaced, discrete streams of air
at high velocity radially into the drum and through the fabric
supported thereon. The drum has a fixed width, related to the
maximum width capacity of the processing line, and has associated
therewith a novel and particularly advantageous tenter guide
arrangement of adjustable width. The tenter guide includes
adjustable tenter chain guides which closely surround the drum
while being supported internally of the drum. The guides are
engaged at one or more points radially externally of the drum for
axial adjusting movement for regulating the width separation of the
tenter chains. The arrangement is a simple, reliable, and wholly
effective structure for accomplishing width control adjustments
without interfering with the critical uniformity of air flow
through the fabric. In addition, the tenter width adjustment
according to the invention accommodates a rugged construction which
can tolerate the severe operating conditions encountered, which
typically include being splattered and coated with excess
heat-curable resins, for example.
The invention is additionally directed to improved tenter
arrangements for engaging the fabric in advance of the processor
and directing the fabric edges to set the fabric at a predetermined
width and conveying the fabric continuously and uninterruptedly
into the processor, around the circumference of the drum and out of
the processor stage, all under conditions which maintain the
geometric uniformity of the fabric, including cross line
straightness. In accordance with one specific aspect of the
invention, for example, a pair of spaced tenter chains is driven by
imparting driving power to one chain only through a suitable
sprocket means. The driven chain serves to drive the rotatable
processing drum through the friction of the extended contact as the
chain passes around the circumference of the drum. The second
tenter chain is driven by its frictional contact with the drum. In
this manner, the greatest uniformity of edge advancement of the
fabric along opposite sides is assured during the period when the
fabric is travelling over the drum. Where appropriate, the drum may
be driven directly from the motive source, with both chains being
driven synchronously by the drum.
Another specific inventive feature of the tenter chain arrangement
resides in the provision of a specifically novel edge-seeking
arrangement for the input end of the tenter. Thus, the tenter chain
may be adjusted principally for a predetermined width and alignment
but the fabric being supplied to the input end of the tenter,
particularly with knitted fabrics because of its geometric
instability, may not have its edges properly aligned with the
principal portions of the tenter. Through suitable controls, which
may in themselves be somewhat conventional, the input end
extremities of the tenter chains may be manipulated to seek and
follow the actual edges of the incoming fabric, so that the fabric
edges are properly impaled upon the tenter pins. Of specific
inventive significance, the tenter chain itself and the guide
channel arrangement therefor is especially constructed to
accommodate the lateral flexing necessary for edge-seeking, without
unduly stressing the chains and without undesirably affecting the
linear relationships between the advancing chain and the advancing
fabric.
In the tenter-conveying of a wet knitted fabric, for example,
severe distortions of the fabric can result if the fabric is not
adequately supported while it remains in a wet condition. To this
end, the apparatus of the invention includes an intake tenter
section which includes means such as conveyor belts to support
fabric as it advances to the dryer housing. Within the housing, the
fabric is supported on a "cushion" of low velocity air, as it
advances through a preheating zone, toward the main drum. Once on
the drum, of course, the fabric is mechanically supported across
its full width on one surface, and thus may be acted upon by high
velocity air jets for highly efficient drying or processing
action.
The invention also includes novel and improved adjustable
tach-follower controls for controlled overfeeding of the fabric
onto the tenter chains, and controlled removal of the processed
fabric. At the entry end, there are provided separately adjustable
tach-follower controls for feeding the opposite edges of the fabric
onto the tenters, for controlled overfeeding and cross line
adjustment. At the discharge end, an adjustable tach-follower
control is provided for removal of the fabric from the tenter pins.
This enables the fabric speed to be properly readjusted to
accommodate geometrical changes in the fabric (typically, slight
narrowing and corresponding lengthening of the laterally distended
fabric) as it is released by the pins.
The invention is applicable to the processing of fabric in either
its wet or dry condition and is particularly useful for drying
and/or curing of wet processed, impregnated various knitted
fabrics, for example, the heat setting of polyester or nylon
fabrics, or other fabric processing operations involving the
maintenance of precise geometric stability during processing. In
addition, the system of the invention accommodates high speed,
efficient commercial-scale operations with a variety of fabrics and
processing techniques. The starting material may be in tubular form
or not and may or may not be subjected to an in-line preparatory
treatment, such as wet-out or chemical impregnation.
For a better understanding of the above and other advantageous
features of the invention, reference should be made to the
following detailed descriptions and to the accompanying
drawing.
DESCRIPTION OF THE DRAWING
FIG. 1 is a simplified top plan view of a processing system,
incorporating the invention, for the handling and processing of
knitted or other fabric web in open width form.
FIG. 2 is a simplified elevational view of the system of FIG.
1.
FIG. 3 is an enlarged elevational view, with parts broken away,
illustrating details of the construction of the rotary drum tenter
dryer apparatus of the invention.
FIG. 4 is an elevational view of the apparatus of the invention,
illustrating details of the arrangements for the heating and flow
of drying air.
FIG. 5 is a cross-sectional view taken generally along line 5--5 of
FIG. 4.
FIG. 6 is an enlarged fragmentary plan view showing the
edge-seeking input end section of the tenter frame utilized in the
system of FIG. 1.
FIG. 7 is an enlarged fragmentary cross-sectional view taken
generally along line 7--7 of FIG. 6.
FIG. 8 is an enlarged fragmentary cross-sectional view taken
generally along line 8--8 of FIG. 7.
FIG. 9 is an enlarged fragmentary cross-sectional view taken
generally along line 9--9 of FIG. 8.
FIG. 10 is an enlarged fragmentary cross-sectional view taken
generally along line 10--10 of FIG. 6.
FIGS. 11 and 12 are enlarged fragmentary cross-sectional views
taken generally along lines 11--11 and 12--12, respectively, of
FIG. 10.
FIGS. 13 and 14 are enlarged fragmentary cross-sectional views
taken generally along lines 13--13 and 14--14, respectively, of
FIG. 3.
FIG. 15 is an enlarged fragmentary cross-sectional view taken
generally along line 15--15 of FIG. 1.
FIG. 16 is an enlarged fragmentary cross-sectional view taken
generally along line 16--16 of FIG. 15.
FIG. 17 is an enlarged fragmentary plan view, partly broken away,
illustrating construction details of an advantageous form of tenter
chain incorporated in the system of FIG. 1.
FIG. 18 is an enlarged fragmentary cross-sectional view taken
generally along line 18--18 of FIG. 17.
Referring now to the drawing, and initially to FIGS. 1 and 2
thereof, there is illustrated a typical processing line
incorporating the features of the invention. At the upstream end of
the processing line there is shown a supply container 20 holding a
supply of, in the illustrated instance, tubular knitted fabric 21,
typically in a wet condition. The fabric 21, in rope form, is drawn
out of the supply container, over a roller 22, being de-twisted as
necessary by an attendant operator. The fabric 21 then advances
into the input of a slitting and opening stage generally designated
by the numeral 23.
Most advantageously, the slitting and opening stage 23 is
constructed in accordance with the teachings of the Sidney L.
Carter et al., U.S. Pat. No. 3,289,510, to which reference should
be made for further details. In addition, the slitting and opening
stage may incorporate improvements described and claimed in the
Eugene Cohn et al., United States application Ser. No. 629,326 now
U.S. Pat. No. 3,551,939, granted Jan. 5, 1971.
In general, the slitting and opening stage includes a slitting
knife 24, which cuts the advancing tube of knitted fabric, and
incorporates a pair of divergently related tenter chains 25, 26,
which engage the newly formed edges of the fabric immediately
adjacent the slitting knife. The arrangement is such that the edges
of the slit fabric are simultaneously advanced and separated, until
the fabric is converted from a slit, but otherwise tubular form, to
a flat, open width form, substantially as indicated at 27 in FIG.
1. As explained in more detail in the before-mentioned Carter et
al., patent and in the Eugene Cohn et al., application Ser. No.
629, 326, the described slitting and opening device is particularly
advantageous for (although not necessarily limited to) the slitting
and opening of tubular knitted fabric in a wet condition. This is
desirable because, in a typical situation, the knitted fabric 21,
as received from the supply container 20 will be in a still-wet
condition from a previous wet-processing operation, such as dyeing,
bleaching, etc.
At the discharge end of the slitting and opening stage 23, the now
open-width fabric 27 passes over a guide roller 28, under a
floating control roller 29 and over a second guide roller 30, and
thence proceeds onto a padding stage, generally designated by the
numeral 31. The floating roller 29 serves an advantageous control
function by sensing out-of-phase speed relationships between the
slitting and opening stage and the subsequent stages. Through
appropriate control circuitry not specifically illustrated herein,
corrective speed changes are made automatically.
Where desirable or expedient, means such as an air guide
arrangement may be provided, directly in advance of the padding
stage, for accurately centering the fabric. Edge decurlers may also
be provided for laying the fabric edges flat and preventing
fold-over of the edges as the fabric enters the pad. Especially
advantageous forms of air guiding and de-curling arrangements are
shown in the co-pending application of Eugene Cohn et al., Ser. No.
611,609, filed Jan. 25, 1967 and now U.S. Pat. No. 3,494,011,
granted Feb. 10, 1970.
The fabric 27 entering the padding stage 31 is directed through a
series of pressure-contacting nip rollers 32, which are
advantageously submerged in a bath of treating liquid maintained in
a suitable retaining tank. The fabric thus is directed through a
plurality of submerged pressure nips, which successively squeeze
and release the submerged fabric, after which the fabric passes
through a pair of extracting rollers 33.
The padding stage advantageously is located directly in advance of
the drying stage, designated by the reference numeral 34, and
serves to impart to the fabric, in advance of drying, a uniform
liquid content, not only edge to edge but along the length of the
fabric. In this respect, a wet-processed fabric retained in the
supply container 20 may be partly immersed in a residual quantity
of the original processing liquid, such that the fabric emerging
from the supply container may vary in liquid content from damp to
soaking wet. If fabric in this condition were directed through the
drying or heat processing stage it would dry (or cure, heat set,
etc.) at non-uniform rates, depending upon the initial liquid
content of a given area. This could introduce serious geometrical
distortions in the fabric and also could cause migration of dyes
and treating chemicals in the fabric. In accordance with the
invention of our co-pending application Ser. No. 625,725, now
abandoned, the liquid content of a wet-processed fabric is caused
to be uniform throughout, by means of processing the fabric in the
padding stage 31, so that the subsequent drying or heat processing
of the fabric proceeds uniformly.
Fabric discharged from the padding stage 31 advantageously passes
over guide rollers 35, 36, and under a floating control roller 37,
which serves to maintain proper speed relationships between the
heat processing and padding stages. The fabric then advances to a
tenter pinning stage, generally designated by the numeral 38, at
which the fabric edges are applied over the pins of spaced tenter
chains. As will be described in more detail, the tenter pinning
stage 38 includes fabric edge-seeking controls for manipulating the
input ends of the tenter chains inward and outward, as required, in
order that the tenter pins engage the fabric edges along a desired
margin. The edge-seeking portions of the tenter chains are
manipulated independently of the basic width adjustment of the
chains, such that the pinned fabric ultimately is conveyed through
the remainder of the process at a uniform, preadjusted width.
At the pinning stage, the fabric is also desirably applied to the
tenter pins in such a way as to provide a predetermined amount of
"overfeed" of the fabric across its width, to accommodate a
reasonable amount of lengthwise shrinkage of the fabric during the
subsequent heat processing stage and also to accommodate shortening
of the fabric which accompanies its widthwise distension. In
connection with the processing of knitted fabric in particular,
provision for lengthwise relaxation shrinkage is important, in
order that the processed fabric have reasonable geometric
stability.
As reflected schematically in FIGS. 1 and 2, the open width fabric,
now pinned on the tenter chains, is conveyed into the heat
processing stage 34 and, while still on the tenter pins, is carried
about a large diameter rotating processing drum 39. While passing
about the drum, the fabric is subjected to the action of a series
of closely spaced high velocity streams of heated air, which are
directed radially inward of the drum 39 from the air ducts closely
embracing the circumference thereof.
After leaving the processing drum, the now dried or otherwise
processed fabric, still engaged by the tenter chains, is conveyed
through a cooling stage, generally designated by the reference
number 40, and to a de-pinning stage, generally designated by the
numeral 41. Thereafter, the fabric is conveyed to a suitable
gathering stage, generally designated by the numeral 42, which
typically may be a horizontal plane folder, or may be a wind-up
apparatus, as will be understood. Guide rolls 43, 44 and an
associated floating control roll 45 advantageously may be
interposed between the de-pinning stage 41 and the gathering stage
42, to maintain appropriate speed relationships between these
stages.
The drying or processing stage 34, forming one of the particularly
important aspects of the present invention, is illustrated
particularly in FIGS. 3-5, 13 and 14. The illustrated processing
apparatus includes a large, typically rectangular housing 46, which
includes a central chamber 47, in which is rotatably supported the
large diameter cylindrical processing drum 39. The drum 39 is of
fixed axial length, which is slightly greater than the maximum
width of the fabric to be accommodated by the system.
The processor housing 46 also includes plenum chambers 48, 49,
which closely surround most of the circumference of the drum 39 and
extend from one end to the other of the working length of the drum.
Beyond the ends of the drum 39, the plenum chambers 48, 49, on each
side of the housing, there are provided enlarged end chambers 50,
51. These end chambers provide an open and unrestricted
communication with the axial ends of the processing drum 39, to
accommodate a free axial flow of air out of the ends of the drum
and into the end chambers, generally in accordance with the
teachings of the U.S. Pat. No. 3,065,551, of Samuel Cohn et al.
At each end of the dryer housing 46, the end chambers 50, 51 are in
communication with blower intake chambers 52, 53 (for the end
chamber 50) and 54, 55 (for the end chamber 51). Each of the intake
chambers 52-55 is associated with adjacent blower outlet chambers
52a-55a. As shown in FIG. 5, the blower outlet chambers 52a, 54a
discharge into opposite sides of the plenum chamber 48, while the
blower outlet chambers 53a-55a discharge into opposite sides of the
plenum chamber 49. The arrangement is such that air from the
respective end chambers 50, 51 is divided and flows in opposite
directions into the blower intake chambers 52, 53 and 54, 55. This
air flows through blowers 56-59 (see FIG. 1) driven by suitable
motors 60, such that the air is directed under pressure into the
plenum chambers 48, 49, where air from opposite end chambers 50, 51
is recombined.
Advantageously, air entering the several blower intake chambers
52-55, is heated by means of gas burners 61 (see FIG. 4) disposed
adjacent the intake openings 62 to each of the blower intake
chambers. Typically, the gas burners 61 may be supplied through
distribution pipes 63 connected to vertical pipes 64 extending from
the floor of the dryer housing 46 up to the burners 61. As
illustrated particularly in FIG. 4, the blower intake and blower
outlet chambers 52-55 and 52a-55a, typically may be of
substantially smaller dimensions than those of the end chambers 50,
51, for example. Thus, the blower intake and outlet chambers may
extend from the forward and rearward walls 65, 66 of the processor
housing substantially at the level of the axis to the drum 39.
These chambers, while extending from one side to the other of the
housing, may be approximately one-half the height of the housing,
so that the upper and lower walls 67, 68 of these chambers are
disposed well below and well above the top and bottom walls 69, 70
of the processor housing. As reflected in FIG. 4, the blower units
56-59 and the drive motors 60 therefor advantageously are mounted
on the top walls 67 of the blower chambers, so as not to extend
appreciably above the top walls 69 of the main housing. The bottom
walls 68 of the blower chambers are spaced well above the floor
level 71, on which the unit is supported, to accommodate the
extension of incoming and outgoing tenter chain sections 72,
73.
As indicated best in FIGS. 3 and 5, air discharged under pressure
from the blower outlet chambers 52a-55a, enters the plenum chambers
48, 49, which are comprised of arcuate, approximately semi-circular
air ducts. These ducts include end walls 74, 75 on one side and 76,
77 on the other side of the processing drum. In addition, each
plenum chamber includes an arcuate, approximately semi-circular
wall 78 or 79 which closes in the chamber and is concentric and
closely spaced from the outer wall of the processing drum 39. By
way of example, in an apparatus in which the processing drum is
about 7 feet in diameter, the spacing between the arcuate duct
walls 78, 79 and the outer wall of the drum 39 advantageously is on
the order of, say, 11/2 to 2 inches.
About the entire surface of the arcuate duct walls 78, 79, there
are provided air nozzles 80, which advantageously extend
transversely entirely across the plenum chambers 48, 49. As
illustrated in FIG. 3, these transversely disposed air nozzles 80
may be spaced a few (e.g., 3 to 4) inches apart over the entire
area of the arcuate duct walls 78, 79, and may have a nozzle width
of about one-quarter to one-half inch. The arrangement is such
that, when air under pressure is supplied to the chambers 48, 49, a
large plurality of narrow, discrete air streams, each extending
entirely across the width of the plenum chambers, are directed out
of the nozzles 80, in a radially inward direction with respect to
the processing drum 39. As will be described, the cylindrical outer
wall of the drum is constructed of a perforate material, such as a
wire screen or mesh, such that the air streams issued from the
nozzles 80 are directed toward and through the outer wall of the
drum and through any fabric supported thereon.
Most advantageously, the pressure relationships existing within the
housing 46, are such that the discrete air streams being issued
from the nozzles 80 are of relatively high velocity (e.g., on the
order of 2,500 to 4,000 ft. per minute) such that each of the air
streams issuing from the large plurality nozzles 80 is relatively
distinct, and a given area of fabric, being conveyed through the
processor on the surface of the drum 39, is alternately and
repeatedly subjected to the action of separate and distinct high
velocity air streams. As described in connection with the
before-mentioned Samuel Cohn et al., U.S. Pat. No. 3,102,006, this
air flow pattern, in conjunction with a predetermined overfeeding
of the fabric into the processor in the first instance, enables a
particularly efficient drying or heat processing action to be
realized, accompanied by repeated manipulation and working in the
fabric to promote relaxation shrinkage in the lengthwise
direction.
As shown in FIG. 4, the plenum chambers 48, 49 advantageously
terminate in the upper portion of the processor housing 46, in
slightly spaced relation to each other. This provides a transverse
passage 81 at the top of the housing for the flow of excess air out
into the end chambers 50, 51. The plenum chambers also terminate in
spaced relation in the lower portion of the housing, to accommodate
the handling of the incoming and outgoing fabric, as will be
explained in more detail. Overall, each of the arcuate walls 78, 79
of the plenum chambers 48, 49, may embrace approximately
150.degree.-160.degree. of the surface of the drum 39, so that a
maximum area of the drum is exposed to the action of the processing
air.
On the incoming and outgoing sides of the processor housing, there
are provided pre-heating and post-heating chambers 82, 83. These
advantageously are located in the lower portions of the housing, so
as to be positioned adjacent lower quadrants of the central chamber
47. The chambers 82, 83 consist of a series of upper and lower air
nozzles 84, 85, which are positioned, respectively, above and below
the plane of the incoming open width fabric, being conveyed in on
the incoming and outgoing tenter chain sections 72, 73. Closely
spaced, discrete, low velocity streams act upon the upper and lower
surfaces of the fabric, as it enters the housing 46, and throughout
a zone of several feet in length, prior to advancement of the
fabric onto the surface of the processing drum.
Advantageously, the air nozzles 84, in the pre-heating and
post-heating chambers, are adjustable in opening size relative to
the lower nozzles 85, as by means of an adjusting shaft 86,
rotatable by a lever 87. The arrangement is such that, air under
pressure supplied to the pre-heating and post-heating chambers is
controllably directed through the upper and lower air nozzles 84,
85, in a manner such as to provide a net upward pressure of air
flowing from the lower nozzles 85. This is particularly significant
in connection with the pre-heating chamber 82, because the fabric
entering and passing through the pre-heating chamber, engaged at
its opposite edges by tenter chains, is wet and heavy and tends to
sag between the supported edges. The net upward force of the air
streams in the pre-heating chamber provides an advantageous support
for the center area fabric to avoid sagging and distortion of the
fabric. If desired or expedient, the upper nozzles 84 may, in some
cases, be closed off entirely.
Air is supplied to the upper nozzles of the pre-heating and
post-heating chambers 82, 83, by means of openings 88, which
connect the lower portion of the plenum chambers 48, 49, with the
respective pre-heating and post-heating chambers. The size of the
openings may be adjustable, as through a shaft 89 and lever 90, to
provide for proper apportionment of flow in the various chambers.
The air is supplied under a pressure suitable to achieve a
relatively low velocity flow at the nozzles. A velocity on the
order of 600 feet per minute is typical and advantageous.
In the illustrated apparatus, the adjustable openings 84, 88 are
formed by slidable nozzle sections 91, 92, which are controllably
positioned relative to opposed, fixed nozzle sections through the
control levers 87, 90. For some installations, however, it may be
adequate to set the size of the openings 84, 88 at the factory and
eliminate adjustment features.
The processing drum assembly 39 includes a shaft 93, journaled in
bearing blocks 94, supported by structural frames 95. The frames
are positioned within the end chambers 50, 51, and are spaced
somewhat beyond the end walls 74-77 of the air duct means forming
the plenum chambers 48, 49. The outward spacing of the frames 95 is
such as to accommodate the presence, outside of the duct walls
74-77, of ducts 96, 97, which connect the upper and lower portions
of the pre-heating and post-heating chambers 82, 83.
The drum shaft 93 supports an open, skeleton framework, on which is
supported a cylindrical outer wall 98 of perforate form. This wall
most advantageously is made of a stainless steel wire mesh, for
example, which may in turn have its exterior surface covered by a
mesh of a friction-free material such as an open mesh of fiberglass
yarns coated with a material such as polytetrafluoroethylene (e.g.,
Teflon PTFE). The mesh of friction-free material typically may have
openings on the order of one-quarter inch, while the openings of
the underlying mesh may be somewhat larger, say, one-half inch.
As reflected in FIG. 3, particularly, the interior of the drum 39
is substantially open, as is the end area of the drum. The
arrangement is such that, in the operation of the dryer, a large
plurality of discrete streams of processing air, extending across
the full operative width of the processing drum, are directed
radially into the interior of the drum, through the perforate outer
wall 98, and, of course, through any fabric supported thereon. The
relatively unobstructed interior of the drum permits a free axial
flow of air out of the interior of the drum, from both ends. The
highly enlarged end chambers 50, 51 accommodate this axial air flow
without causing significant localized flow streams of withdrawn air
in and about the processing drum, such as would result in
non-uniformity of drying across the width of the fabric. In this
respect, it is particularly significant that the fabric be dried or
otherwise processed at a uniform rate across its width as well as
along its length, not only to achieve uniform geometric
stabilization, but, more importantly, to achieve uniform curing or
reaction of fabric components or fabric impregnants, such as dyes,
resins, etc. For example, non-uniform drying of a fabric, still wet
from the dyeing process, can cause migration of the dye from one
area to another of the fabric, resulting in a product which is
mottled or otherwise of non-uniform appearance. Likewise, in heat
setting of a polyester or nylon fabric, for example, processing
uniformity, as well as positive geometrical stability, is critical,
because the fabric will assume certain relatively permanent
characteristics during the processing stage.
When the processor is in operation, most of the air withdrawn from
the ends of the drum is heated by the burners 61, recirculated
through the blowers, directed into the plenum chambers 48, 49, and
again discharged through the nozzles 80. However, some percentage
(e.g., 10 percent) of the air is continually exhausted to the
atmosphere and a corresponding amount of fresh air is, of course,
introduced into the system. In the illustrated system, the exhaust
air is most advantageously removed by extraction from the end
chambers 50, 51, through large exhaust openings 100, 101, located
in the outer walls thereof generally opposite the end openings of
the drum. The exhaust openings communicate with large exhaust ducts
102, 103 (FIG. 1) through which the air is discharged to the
atmosphere. Make-up air, to compensate for the volume of air
exhausted, typically is brought into the system through inlet
openings, not specifically shown, which desirably are located so
that the make-up air is acted upon by the heaters before initially
reaching the intakes of the blowers 56-59.
As will be described in more detail, fabric entering the processing
stage 34 is pinned upon spaced tenter chains 105, having an
advantageous configuration as shown in FIG. 13, for example. The
chains are comprised of link bodies 106 and integral offset
extension arms 107, which mount appropriate tenter elements, such
as plates of tenter pins 108, tenter clips (not shown) or the
like.
As the tenter chains advance through the incoming stage into the
interior of the processing stage, the chains are transferred to
guide sheaves 109, which reverse the direction of the tenter chains
and then transfer them to a pair of spaced guide channels 110,
disposed about the entire circumference of the processing drum 39.
When transferred to the guide channels 110, the tenter chains 105
are guided and supported by the inner walls of the channels, such
that the offset extension arms 107 and the pin plates closely
overlie the surface of the outer wall 98 of the drum. This enables
a fabric, engaged by opposed tenter chains, to be supported
directly upon the surface of the processing drum, in the manner
desired, closely adjacent the edge extremities.
As shown particularly in FIGS. 3 and 14, the pair of guide channels
110 is supported from within the processing drum 39 by means of a
plurality (e.g., six in a typical installation) of axially disposed
supporting rods 111, secured to the frame structure of the drum.
Each of the supporting rods 111 guides a carrier bracket 112 having
triangularly arranged trolley wheels 113 engaging opposite sides of
the rod. A connecting arm 114 extends radially from the carrier
bracket 112 and engages the guide channel 110 just outside the
surface of the drum wall 98.
In the illustrated arrangement, each of the guide channels 110 is
supported at six points by a structure as described above and
illustrated in FIG. 14. The arrangement is such that the guide
channels are firmly supported, just slightly spaced outward of the
cylindrical outer wall of the processing drum, in a manner to
provide for inward and outward axial adjusting movement.
To accommodate the desired axial adjusting movement of the guide
channels 110, the end areas of the drum wall 98 are provided with
axial slots 115 (see FIG. 5) extending from the outer end of the
drum inward for a distance sufficient to accommodate the desired
range of adjustment. Typically, in the region of the slots 115, the
screen material forming the outer wall of the drum is cut and bent
inward, as indicated at 116 in FIG. 14, and secures as by clamping
with a strip 117 bolted through the screen to a supporting
structure, such as an angle iron (not shown).
As shown in FIG. 3, the tenter chains 105, after traveling in the
guide channels 110 with the rotating drum 39, throughout an arc of
as much as, say, 330.degree., are transferred to reversing sheaves
118, and then directed into the outgoing tenter stage, as will be
further described.
For effecting inward and outward lateral adjustment of the tenter
chains 105, within the processing stage 34, an advantageous
arrangement is provided for effecting axial adjustment of the
position of the guide channels 110, the reversing sheaves 109, 118,
and other elements of the tenter stages. To this end, there are
disposed within the processor housing, radially outward of the drum
39, and advantageously just within the physical outline of the hot
air ducts 48, 49, a plurality of guide tubes 119 (see FIGS. 3, 14)
which typically extend for the full width of the drum 39 and house
threaded adjusting shafts 120. Each of the guide tubes 119 receives
a slide block 121, which is threadedly engaged by the shaft 120 and
has a tongue 122 projecting through a narrow, elongated slot 123 in
the guide tube, in a direction radially inward of the processing
drum 39, but terminating short of the outer surface thereof. An
extension 124 of the tongue mounts a pair of closely spaced guide
wheels 125, which closely embrace the opposite surfaces of the
radially outwardly extending outer flange of the guide channel 110.
The arrangement is such that, as the drum 39 rotates along with the
guide channels 110, the outer flange of each of the guide channels
is guided and positioned by the pairs of guide rollers 125, at a
plurality of points about the circumference of the drum.
As will be understood, the positioning of the pairs of guide
rollers 125, for each of the several adjustment assemblies, is
coordinated, and the adjustment thereof axially of the drum 39 is
synchronized through synchronous manipulation of the several
threaded shafts 120. Accordingly, through suitable controls,
typically motor driven, the shafts 120 may be controllably
actuated, as necessary, to move the guide channels axially inward
or outward. In typical operation, the drum is being rotated during
an adjusting movement, so that there is relative movement between
the guide channels 110 and the guide rollers 125, which further
assures smooth adjustment.
Advantageously, an elongated cover plate 126 is supported by the
slide block 121 and by supporting blocks 136, within the guide tube
119, to close off the slot 123 while permitting the tongue 122 to
project therethrough. This arrangement is particularly advantageous
because it prevents accumulations of lint, splatterings of resins
and other chemicals from forming around the threaded shaft 120,
ultimately to interfere with its proper operation.
Similarly, the supporting arrangement for the guide channels 110 is
such as to remain substantially maintenance free in a severe
environment. Thus, lint accumulations in the area of the carrier
bracket 112 are effectively prevented by the active air flows,
during normal operation, and the provision of large diameter,
grooved trolley wheels, for cooperation with a cylindrical
supporting bar, keeps the carrier assembly relatively insensitive
to an occasional splattering of chemicals, such as resins.
As will be understood, in effecting an axially inward or outward
axial adjustment of the guide channels 110 and the tenter chains
supported therein, it is also necessary to effect a like adjustment
of the reversing sheaves 109, and also other portions of the tenter
line. To this end, the sheaves 109, 118, as well as the adjacent
ends of the incoming and outgoing tenter stages, are supported by a
carriage frame 127 at each side. As shown best in FIG. 13, the
carriage frames 127 include bearings 128 supporting shafts 129,
upon which are supported the reversing sheaves 109, 118. For
purposes to be explained, the shafts 129 advantageously are of
eccentric form, in that the portion 130 thereof, which supports the
reversing sheave, is offset from the portion received in the
bearing 128. The enables the axis of the reversing sheave to be
adjusted relative to the carriage 127, although this is intended to
be an installation adjustment and is not needed in day-to-day
operations.
The adjacent ends of the incoming and outgoing tenter sections 72,
73, are supported below the reversing sheaves 109, 118 by suitable
brackets 131 secured to the carriage frame and movable
therewith.
At each side, the entire carriage frame 127 is supported on a
trolley structure comprised of base members 132 and pairs of
grooved trolley wheels 133. The trolley wheels 133 are supported
between opposed pairs of tracks 134, 135, which typically may be
formed of the outside corner area of angle sections.
The carriage rails 134, 135 extend widthwise below the processing
drum 39, accommodating inward and outward movement of the sheaves
109, 118 along with the inner ends of the tenter sections 72, 73.
As shown in FIGS. 3 and 13, and also in FIG. 14, the carriages 132
are provided with positioning arms 137, 138, which extend upward
and outward to be engaged by elements 139 (FIG. 14) carried by the
slide blocks 121 of the two lower-most adjusting shafts 120. Thus,
when the several adjusting shafts are actuated, to shift the guide
channels 110 symmetrically inward or outward relative to the drum,
the carriages 132 are simultaneously shifted inward or outward to
adjust the inner ends of the tenter sections 72, 73, and the
reversing sheaves 109, 118.
In the illustrated form of the invention, fabric supporting drums
139 (FIG. 13) extend transversely between opposed pairs of the
reversing sheaves 109, 118. The diameter of the supporting drums
139 approximates that of the tenter chain passing around the
reversing sheaves, such that the tenter-engaged fabric is supported
in its central portions as it is conveyed through a reversing turn.
In the illustrated arrangement, the fabric supporting drums 139 are
arranged for telescopic interaction, so as to expand and contract
with widthwise adjustments of the tenter chains. Alternatively, the
axial length of the supporting drums 139 may correspond to the
minimum width setting of the tenter chains and be of fixed length.
In the alternative arrangement, portions of the fabric near the
edge margins would be unsupported, but this does not appear to
present problems of consequence, as long as the fixed length of the
supporting drums 139 bears a reasonable relation to the overall
width of the fabric. In this respect, a fabric supporting drum 139
having an axial length approximately half of the overall fabric
width is entirely satisfactory.
As is illustrated particularly in FIG. 13, the tenter pins 108,
engaging the fabric as it passes around the reversing sheaves 109,
118, extend in a generally radially inward direction, while the
tenter chain is passing about the sheaves. Accordingly,
longitudinal tensions in the fabric will have an inherent tendency
to "de-pin" the fabric from the tenter chain. To prevent this, the
apparatus of the invention advantageously incorporates a retaining
ring 140 associated with each of the reversing sheaves. The
retaining ring 140 is secured to the inner side of the sheave and
extends radially outward to a point axially inside of and radially
outward of the extremities of the tenter pins. The arrangement is
such that the pinned fabric, which is passing about the reversing
sheaves, is required to pass about the outer extremities of the
retaining rings 140. Thus, tensions which are applied to the fabric
will simply cause the fabric to be pulled more tightly over the
retaining rings 140 and so to be pulled more tightly down onto the
tenter pins.
As previously mentioned, the reversing sheaves 109, 118
advantageously are supported by eccentric shafts 129, such that the
sheaves can be raised and lowered by rotary manipulation of their
supporting shafts. This not only enables the sheaves to be readily
adjusted relative to the surface of the dryer drum 39, but also
enables the sheaves to be raised to a position high enough to
contact and actually support the weight of the drum 39. Through
this facility, construction and installation procedures of the
bulky and cumbersome dryer drum are greatly simplified. Thus, at
the installation site, temporary carriage tracks (not shown) may be
installed outside of the dryer housing, in line with the carriage
tracks 134. The dryer drum, handled entirely outside the dryer
housing, may then be positioned on and supported by the reversing
sheaves previously adjusted to elevated positions. The carriages
132 may then be rolled into the interior of the housing, through a
still open side wall, and the drum thereafter supported in its
regular journals 94. Once this initial installation is completed,
the reversing sheaves may be lowered away from the drum, to their
desired operating positions. The temporary carriage tracks may, of
course, be taken up after the drum is in place within the
housing.
The input section 72 of the tenter, shown particularly in FIGS. 3
and 6-13, inclusive, is comprised of a pair of tenter guide
channels 150, 151 supported at their inner end extremities by the
carriage 132 and at one or more intermediate locations by one or
more adjusting shafts 152. The adjusting shafts 152 are of a
character similar to the shafts 120 and are controlled to be
operated in synchronism therewith, such that the tenter frames 150,
151 are adjusted laterally inward and outward along with the tenter
guide channels 110 of the dryer drum, in accordance with fabric
width settings. As illustrated in FIG. 13, the tenter channels 150,
151 may comprise an assembly of an L-shaped section 153, for
supporting the empty or return reach of the chain, and a Z-shaped
section 154 slidably supporting the active or fabric carrying reach
of the chain. The channel section 154 has an upwardly extending
inner flange 155, which is received between the chain body and the
offset arm 107. In normal operation, the chain body slides against
the outer face of the flange 155, by reason of the slight widthwise
fabric tensions, which tend to draw the tenter chains inwardly.
In accordance with one of the specific features of the invention,
the input tenter section 72 is provided with a novel and
advantageous arrangement for seeking out the edge extremity of the
incoming fabric and pinning the fabric properly upon the tenter
chains 105. Thereafter, the chains advance into the guide channels
150, 151, to be conveyed through the remainder of the system at a
predetermined uniform width dimension. Referring now to FIGS. 6 and
7, the fabric 27, received from the padding stage 31, passes
through a set of triangularly configurated, spiral de-curling
rollers 156 which are rotated so that the spiral surfaces thereof
tend to smooth out and de-curl the fabric. The fabric then is
directed through reverse bends about a pair of speed-controlled
overfeed rollers 157, which are driven in a predetermined speed
relationship to the tenter chains, advantageously at a somewhat
higher rate of speed to provide for a desired degree of overfeeding
of the fabric onto the tenter pins. Desirably, the overfeed rollers
157 are separated, so as not to nip the fabric, but are provided
with suitable friction surfacing which, by reason of the
considerable area of contact with the fabric, affords an adequate
grip for controlling the fabric in an effective manner.
Fabric discharged from the upper gripping roller 157 passes between
pairs of air jet uncurlers 158, 159 carried by edge-seeking tenter
sections generally designated by the numerals 160, 161, which are
connected to and form the entry ends of the respective tenter
channels 150, 151. The edge uncurlers 158, 159 are arranged to
direct jets of air outwardly across the top and bottom surfaces of
the fabric, to at least momentarily flatten the fabric. In this
respect, it will be understood that many slit and opened tubular
knitted fabrics, for example, have a pronounced tendency to curl at
the edges, particularly when subjected to any lengthwise tension
during processing, and it is often necessary to de-curl the fabric
at one or more stages for effective handling.
While the fabric edges are held flat by the uncurling jets 158,
159, the fabric passes between an edge sensing control 162,
typically consisting of means such as a light source 163 and a pair
of photoelectric cells 164, 165. The sensing controls are provided
at both sides of the equipment, of course, to detect the opposite
edges of the fabric. The arrangement of the control is such that,
if neither of the photoelectric cells is covered by the fabric
edge, the edge-following section of the tenter chain will
automatically adjust in an inward direction, until it "finds" the
fabric edge. The adjustment will terminate when the inside cell 165
is covered by the fabric edge, while the outside cell remains
uncovered. If the fabric edge wanders in an outward direction, to
cover both of the photo cells, an outward adjustment of the tenter
section will automatically follow, until the outer photoelectric
cell 164 is again uncovered.
Still referring to FIGS. 6 and 7, the uncurled fabric edge,
properly tracked by the sensing control 162, passes directly
between a trimming roll 166, driven by a motor 170, and a pinch
roller 167 cooperating therewith, whereby the fabric edge is
positively advanced at a predetermined, controlled speed, typically
somewhat greater than that of the tenter chains 105. The fabric is
then advanced between a driven brush wheel 168 and cooperating,
opposed plate 169. The brush wheel is disposed directly above the
tenter chain 105 and has its bristles projecting slightly below the
upper extremities of the tenter pins 108. The brush wheel 168 is
driven at such a speed that its bristle extremities are traveling
at a higher rate of speed than the tenter chain 105, enabling the
fabric to be impaled upon the tips of the tenter pins 108 in a
uniformly, desirably overfed condition.
The lightly pinned fabric then advances to a second non-driven
brush wheel 171, the bristles 172 of which project substantially to
the base ends of the tenter pins 108. The arrangement is such that,
as the fabric passes under the brush wheel 171, it is pressed
downward to a fully pinned condition. The idling speed of the brush
wheel 171 is, of course, such that its bristles 172 are
substantially synchronous with the tenter chain 105.
In accordance with one aspect of the invention, the draw rollers
157 are speed controlled relative to the speed of the tenter
chains, by means of a so-called tach-follower control (not shown).
The tach-follower control, which is available from com-mercial
sources and by itself forms no part of this invention, drives the
overfeed rollers 157 at a preset but adjustable percen-tage of the
tenter chain speed. Typically, this is set to provide a
predetermined percentage (e.g., 20-30 percent for some knitted
fab-rics) overfeed of the fabric to the tenter input. The overfeed
trimming rolls 166 and brush wheels 168 at each side are in turn
controlled by separately adjustable tach-follower controls related
to the speed of the overfeed rolls 157. This enables a degree of
separate overfeed control of the opposite fabric edges, for final
cross line straightening as the fabric is applied to the tenter
pins.
Advantageously, the overfeed rollers drive sets of conveyor tapes
or belts 198, supported by idler rollers 199 (see FIG. 6). The
belts support the center area of the fabric, as it is conveyed by
the entry stage of the tenter, and prevent it from sagging
excessively under its own weight, particularly when handling wet
fabric.
In accordance with one of the more specific aspects of the
invention, the edge-seeking entry end sections 160, 161 of the
tenter sections are secured to the main tenter channels 150, 151 by
means of special constant-length flexing sections 173, 174, details
of which are illustrated in FIGS. 10-12. In this respect, it will
be understood that the tenter chains 105, to be described in more
detail, are intended to be flexible principally in the vertical
plane, to accommodate travel about the reversing sheaves 109, 118,
about the processing drum 39, and about various other sprockets and
sheaves which are provided to guide and support the travel of the
chain. While limited flexibility of the chain is provided to
accommodate bending in horizontal directions, it is an objective of
the invention to provide for horizontal flexure of the tenter
chains in very gradual arcs and, in addition, to accommodate the
flexure of the chains in unequal amounts in horizontal directions,
without upsetting the desired synchronous relationship between a
cooperating pair of tenter chains.
Referring specifically to FIGS. 10-12, the flexure section 174,
which is a substantial duplicate of the opposite-side flexure
section 173, is shown to comprise the pair of spaced, flexible side
plates 175, 176, between which are positioned a plurality of
flexible strips 177, 178, 179, and 179a. The several plates 175,
176 and strips 177-179 are separated from each other by suitable
spacer means, such as washers 180, as shown in FIG. 12, and spacer
plates 181, shown in FIG. 11. The spacer plates 181 are located at
the end extremities of the flexure sections, while the spacing
washers 180 may be provided at one or more intermediate locations.
In between the spacers, the plates 175, 176 and the strips 177-179
are simply disposed in spaced apart relation, as is clearly
reflected in FIG. 11.
As shown in FIG. 12, the proportions of the plates 175, 176, the
strips 177-179a and the spacers 180, 181 are such as to form a
member of channel-like cross section, in which the tenter chain 105
is received and guided. The channel section 151, shown in FIG. 12,
receives the flexure section within its open side, such that the
upper and lower channel arms 182, 183 form, with the flexure
section 174, a pair of closed channels for the upper and lower
reaches of the tenter chain. The upper reach of the chain is
supported on the upper edges of the strips 177-179a, while the
lower reach of the chain is supported on the lower channel arm 183.
Likewise, the chain sections are confined laterally between the
side plates 175, 176 of the flexure section, with the inner side
plate 176 being received between the chain link bodies and the
offset arm portions 107 extending therefrom.
In accordance with the invention, the several flexible strip
sections 175-179a are slidably related to each other such that,
notwithstanding the rather substantial width of the laminate-like
assembly, it may be readily flexed over its length in a uniform,
gradual bend. In addition, it is a feature of the invention that
the flexure sections 173, 174 do not change significantly in
effective length along the center line of the section, as formed by
the central flexible strip 178. To this end, the flexure section
174 is secured to the tenter channel 151 by means of bolts 184
which extend completely through the flexure section and through the
side wall of the channel section 151, as illustrated in FIG. 11.
The bolts 184 are provided with enlarged bushing inserts 185 which
extend through elongated openings 186 in the side plate 176 and the
flexible strips 179, 179a. The elongated openings 186 are of a
width (top-to-bottom) corresponding to the bushing 185, so that the
elements 176, 179, 179a are accurately guided for relative movement
in a lengthwise direction, while being fully supported in the
vertical plane.
The central strip 178 of the assembly, along with the separating
elements 181 on either side thereof, are bored to closely receive
the body sections of the bolts 184, so that no relative movement
between these elements and the bolts 184 is accommodated. The outer
side plate 175 and the adjacent strip 177 are provided with
elongated openings 187 similar to the openings 186, and these last
mentioned elements are separated by a plate 181 which is provided
with circular bores 188. Bushings 189 extend through the openings,
187, 188 and bear against the surface of one of the plates 181
adjacent the central strip 178.
As shown in FIG. 11, the bolts 184 extend through the side wall of
the tenter channel 151 and are tightly engaged by nuts 190. In
accordance with the invention, the length of the bushings 185, 189
is such as to enable the central flexible strip 178, together with
the plates 181 immediately adjacent the strip on either side, to be
tightly clamped in fixed relation to the tenter channel 151. The
flexible strips 177, 179, 179a and the side plates 175, 176 are
loosely accommodated by the fully tightened-down bolts, to provide
for lengthwise relative movement of the loosely accommodated
members, within the limits provided by the elongated slots 186,
187.
At the opposite ends of the flexure sections 173, 174, bolts 191
secure the laminate-like assembly to the entry section assemblies
160, 161, such that the center flexible strip 178 is rigidly
related to the entry section, while the other flexible strips of
the assembly are loosely accommodated for lengthwise relative
movement.
At one or more locations intermediate the end extremities,
depending on the overall length of the flexure assembly, bolts 192
may be provided. These bolts will extend from one side to the other
of the flexure assembly, with end washers 193 being clamped tightly
between an elongated bushing 194, such that the entire stack of
flexible plates and strips, together with spacing washers 180, is
loosely accommodated to provide for limited relative sliding
movement between the bolts 192 and the flexible elements.
The arrangement of the flexure sections 173, 174 is such that the
entry sections 160, 161 of the tenter sections may be flexed
inwardly, relative to the principal longitudinal axis of the tenter
channels 150, 151, by inward bending of the flexure sections. The
flexure sections are of substantial length, relative to the width
of the chain track (e.g., about 2 to 6 feet in length for a chain
body of around 1 inch in width), so that the lateral bending of the
chain track is very gradual. Thus, in a practical installation,
using a heavy duty tenter chain capable of withstanding substantial
tension forces and of being subjected to environmental extremes,
the sections can easily be directed through a gradual bend of
10.degree., or so overall, which is suitable for most
installations, or a much larger angle if desirable or expedient. A
flexure of this angular extent, when related to the overall length
of the flexure element plus the additional length of the entry
sections 160, 161, provides for a substantial transverse movement
of the entry end extremity of the tenter chain sections for
edge-seeking purposes and to provide for a significant amount of
widthwise distension of the fabric.
Of significance, substantial flexure of the sections 173,174 is
provided for without affecting the overall length of the tenter
chain. In other words, by bending the flexure sections
substantially along their respective center axes, the axis of the
chain is neither lengthened nor shortened by movements of the
sections 173, 174. This is desirable, because it frequently may be
the case that one of the flexure sections may be bent to a much
greater degree than the other, as if the fabric entering the tenter
section is slightly off center of the longitudinal center line. In
this respect, it will be understood that it is most desirable to
establish and maintain a straight-across relationship of the stitch
lines of the fabric, which may require complicated adjustment if
the chains are caused or permitted to travel through different
distances during the period in which the fabric is being
conveyed.
Advantageously, provisions are made for limiting the angular extent
of flexing of the sections 173, 174. This may be accomplished by
means of a pair of limit switches 200, 201 carried by a guard plate
assembly 202 on each of the tenter channels 150, 151. By means,
such as an arm 203 carried by the tenter input sections 160, 161,
the switches 200, 201 may be tripped at the inner and outer
extremities of movement of the flexure sections 173, 174.
Typically, the limit of outward flexure may be when the entry
sections 160, 161 are aligned with the tenter channels 150, 151,
inasmuch as edge-seeking outside of the main tenter path would be
an abnormal circumstance. The limit of inward flexure may be set at
about 10.degree. of angle, or more, depending upon the needs of a
particular installation.
Control of the inward and outward movement of the tenter input
sections 160, 161 is effected by separate motors (not specifically
shown) which drive screw shafts 204, 205 (FIG. 6) in one direction
or the other, in response to the edge sensing of the photoelectric
cells 164, 165, as previously described. However, should the edge
sensing control tend to adjust one of the input sections beyond its
limit switch conditions, the adjusting movement automatically will
be terminated and typically a suitable signal will be provided to
the operator. In addition, the limit switches 200, 201
advantageously are related through other contacts to the
edge-seeking adjustment motors, such that, when the limit switches
200 or 201 are tripped during inward and outward adjusting
movements of the tenter channels 150, 151, the entry sections 160,
161 automatically will follow along with the basic tenter width
adjustment. In other words, inward width adjustment of the tenter
channels 150, 151, in the condition shown in FIG. 6, would cause
the switch 200 to be tripped by the actuating plate 203, and this
would energize the edge-seeking adjustment for the entry section
160, enabling the entry section to follow along with the inward
adjustment of the remainder of the tenter section.
As shown in FIGS. 8 and 9, the shafts 204, 205 (of which only shaft
205 is shown in FIGS. 8 and 9) for the edge-seeking adjustment
mechanism are housed within a tubular element 206 which extends
from one side of the apparatus to the other and is provided with a
slot 207 in its upper wall. A slide block 208, threadedly engaged
with the shaft 205, is housed within the tubular element 206 and
has a T-shaped assembly, consisting of a block 209 and a flat plate
210 secured thereto and exposed above the upper wall of the tubular
element. A plate assembly 211, constituting a part of the tenter
entry section 161, is slidably supported on the flat plate 210,
through a pair of blocks 212, 213 formed of a suitable antifriction
plastic material.
A pivot block 214, also advantageously formed of a low friction
plastic material, is carried by the plate 210 for limited
rotational movement about the axis of a large bushing 215 secured
to the slide block 208 by a bolt 216. A pair of metal guide bars
217 are secured to the plate assembly 211 and bear against the
longitudinal side edges 218 of the pivot block 214.
The arrangement of the mechanism illustrated in FIGS. 8 and 9 is
such that, upon rotation of the threaded shaft 205 to advance the
slide block 208 inward or outward, the plate assembly 211 may have
relative longitudinal movement with respect to pivot block 214, and
the latter may also pivot slightly, to accommodate the necessary
flexing movements of the flexing sections 173, 174.
The discharge side tenter section 73 is comprised of a pair of
elongated tenter guide channels 220 (see FIG. 15) which are
supported at their inner ends by the carriages 132 and at their
outer ends by a pair of carriages 221. Each of the carriages 221
includes a spaced pair of carriage wheels 222 resting on a
relatively large diameter tubular supporting track 223. The track
223 is supported at its opposite ends by spaced stanchions 224.
As shown in FIGS. 15 and 16, the outer end portions of the tenter
channels 220 are supported by short beam structures 225, to which
the carriages 221 are attached. The beam structures 225 include a
pair of spaced plates 226, which receive between them, at the outer
end of the structures, tenter chain sprockets 227. The sprockets
227 for the spaced tenter chains advantageously are carried by a
common sprocket shaft 228, which is supported by and extends
between the spaced stanchions 224. By means of suitable journal
blocks 229, slidably related to the shaft 228, the beams 225 and
the sprockets 227 may be adjusted transversely with respect to the
shaft 228, for effecting width-wise adjustment of the tenter
chain.
In the illustrated arrangement, width adjustment of the discharge
tenter section 73 is effected through adjustment of the carriages
132, within the dryer housing, and through operation of a threaded
adjusting shaft 230, adjacent the outer end of the tenter section.
The shaft 230, is, of course, suitably connected to the other
adjusting shafts 120, 152 of the installation.
In order to keep the tenter chains 105 under proper tension, under
all operating conditions, to compensate for wear and stretch of the
chains (which may be unequal on opposite sides), each tenter chain
system is provided with a pair of stationary and movable sheaves
231, 232. The stationary sheaves 231 are journaled by the beam
structure 225, while the movable sheaves 232 are supported by pivot
arms 233 carried by the shafts 234 of the sheaves 231. The movable
sheaves 232 are acted upon by air cylinders 235, typically
maintained under a constant pressure, such that the movable sheaves
tend to be pivoted in a counterclockwise direction, as viewed in
FIG. 15. The tenter chains 105 are trained sinuously about the
stationary and movable sheaves 231, 232 such that, when the air
cylinders 235 are in an actuated condition, the chains are
maintained in a constant, predetermined operating tension.
Above the discharge end of the tenter chains 105, there is
advantageously provided a pair of full width pick-off rollers 236,
237 provided with fabric gripping surfaces and arranged to be
driven through an adjustable tach-follower control at a speed
referenced to that of the tenter chain. Typically, the rollers 236,
237 may be slightly separated, so that the fabric is not nipped in
passing between them, but the configuration of the rollers is such
that the fabric is caused to travel through a sinuous path in
passing about the rollers, to provide for a substantial area of
gripping contact with the roller surfaces. The pick-off rollers
236, 237 serve to draw the fabric upwardly off of the tenter pins,
at the discharge end of the tenter chains and to cause the depinned
fabric to be advanced toward the "batching" stage 42 at a
readjusted speed to reflect changes in fabric geometry upon
depinning. The illustrated batching stage is a folding stage, but
may be a rolling or other batch collecting stage, as desired.
In accordance with one of the advantageous specific aspects of the
invention, the pair of tenter chains 105 of the system is driven
through a single power input to one chain only. More specifically,
the tenter chain drive motor (not specifically illustrated) is
connected to the shaft 228, which is slidably keyed to a first one
of the tenter chain sprockets 227 while being rotatable relative to
the other tenter chain. Accordingly, the tenter chain drive motor,
when actuated, drives only one of the two tenter chains through a
direct sprocket connection.
As will be understood, the single driven tenter chain, in traveling
around the processing drum 39 within its annular guide channel 110
will rotate the drum in exact synchronism with the travel of the
chain. In this respect, it will be understood that the frictional
contact of the driven chain with its annular guide channel 110
extends over a sufficient length to establish a positive driving
relationship between the chain and the processing drum.
In accordance with the invention, the second tenter chain, whose
discharge end sprocket 227 is freely rotatable relative to the
drive motor, is driven by the processing drum 39, through a
frictional contacting relationship with the other annular guide
channel 110. The described arrangement for driving of the spaced
pair of tenter chains assures the most precise synchronism of chain
travel throughout the system, particularly throughout the extent
over which the chains are conveying the pinned fabric, and more
particularly still, through the critical processing stage. If
desired, provision can be made for disconnecting the first drive
sprocket and keying the other to the shaft 228, so that the
"driving" and "driven" chains may be alternated from time to time
to equalize wear.
As will be understood, the tenter chains of a typically
proportioned installation according to the invention are of quite
substantial length overall. As a result, even though both chains of
a pair contain exactly the same number of chain links and are
driven by synchronously rotating sprockets, keyed to the same
shaft, the actual linear travel of the chains may be somewhat
different. In some cases, this can result from cumulative,
non-compensating tolerance variations in the chain links
themselves. In other cases, the variation may be a result of
unequal changes in the overall length of the chain caused by
exposure to uneven temperatures or other conditions. Regardless of
the cause, an unequal linear travel of two chains driven by
synchronous sprockets and containing the same number of chain links
can be expected in an installation of the size contemplated by the
present invention and can result in undesirable angularity in the
cross lines of the fabric.
In the system of the present invention, the tenter chains are
synchronized according to the linear travel of the processing drum
39, rather than as a function of the number of teeth in a sprocket.
This assures precise equality of linear travel of the chains, at
least throughout the critical heat processing stage. In addition,
the processing stage is located more or less in the middle of the
fabric-conveying portion of the chain, which assures optimum
synchronization of the linear travel of the chains throughout the
fabric-carrying portions thereof not actually in contact with the
processing drum.
Under appropriate circumstances, it may be feasible to impart the
power input to the drum 39 itself, such that both tenter chains are
driven by frictional contact with their respective tenter guide
channels 110.
Referring now to FIGS. 17 and 18, there are shown details of an
improved form of tenter chain link construction, adapted
particularly for a tenter apparatus in which the chain is required
to be deviated substantially in more than one plane. In the
illustrated system, for example, the tenter chain is deviated
significantly in the vertical plane, in passing around the various
sprockets and sheaves and in passing around the processing drum 39.
At the same time, it is required to be deviated, although to a
lesser extent, in a horizontal plane, to accommodate the
edge-seeking action of the entry end section of the tenter
apparatus.
Each of the chain links 105 is of cast metal construction and has a
body portion 240, from one end of which extends a single connecting
leg 241 and from the opposite end of which extends a pair of spaced
connecting legs 242. The dimensional relationship of the single and
double connecting legs 241, 242 is such, as reflected in FIG. 17,
that the single leg 241 of one chain link is freely received
between a pair of spaced legs 242 of the next link, with a slight
lateral clearance.
In accordance with the invention, successive chain links are
connected by means of split roll pins 244, of a type available from
conventional commercial sources. The roll pins 244 are of a length
to extend across the full width of the chain link, being fully
received in a spaced pair of connecting legs 242, but preferably
not extending laterally outward therefrom.
Advantageously, the transverse bore 245, extending through the
spaced legs 242 for the reception of the roll pin 244, is of a size
to form a tight frictional grip with the roll pin, placing the pin
under compression by slightly closing its split 246. The bore 247
provided in the single connecting leg 241 is, on the other hand,
advantageously of a size to accommodate relatively unrestricted
rotational movement of the connecting leg 241 about the axis of the
roll pin, while the pin remains immovable in the spaced connecting
legs 242.
To provide for a predetermined amount of lateral flexibility in the
tenter chain, the roll pins 244 are oriented in the spaced legs 242
with their split portions 246 lying in the plane containing the
axes of both roll pins connecting that link to the adjacent links.
With this arrangement, when successive links are substantially in
the same plane, the split area 246 provides, in effect, a "flat" in
the plane of the chain links, and this facilitates a degree of
lateral deviation of one link relative to another in such
plane.
The advantageous connecting arrangement for the tenter chain links
is such as to provide an adequate degree of lateral flexibility of
the chain, while at the same time keeping the chain substantially
free of looseness in the lengthwise direction.
As indicated particularly in FIGS. 12 and 18, the chain link body
105 includes an integral extension arm 107, which extends downward
and inward from the upper surface area 248 of the link body. At its
lower extremity, the projecting arm 107 has an integral lateral
extension 249 which seats a pin plate 250 carrying a plurality of
upwardly and outwardly projecting tenter pins 108. Suitable tenter
clips or the like may also be employed in place of pins, as will be
understood.
As reflected in FIG. 12, the lateral extension 249 of the
projecting arm 107 advantageously is disposed below the lower
surface 253 of the chain link body. The desired arrangement is such
that, when the chain links are received in the annular guide
channels 110, disposed about the processing drum 39, the arm
extensions 249 lie as close as practicable to the surface of the
dryer drum. This enables the pinned fabric to be supported by the
drum across the fullest extent of its overall width.
SUMMARY OF OPERATION
In the operation of the described system, it is advantageous to set
the speed of the overall system by controllably adjusting the speed
of the drive motor for the driven tenter chain, to thereby control
the speed of operation of the heat processing stage, and to cause
other functioning elements of the system to respond on a demand
and/or tach-following basis. In this respect, it will be
understood, that, in accordance with one aspect of the invention,
power input is applied directly to only one of the pair of tenter
chains. This directly driven chain serves to drive the processing
drum 39, and the motion of the drum is utilized to drive the second
tenter chain in precise linear synchronism with the first tenter
chain.
At the input end of the tenter chains, the fabric edges are
uncurled and "followed" by the described edge-seeking controls, so
that the edge margin of the fabric is properly engaged by the
tenter means. The edge-seeking function of the tenter chains is, of
course, substantially independent of the operating speed of the
line.
In order to provide a predetermined, controllable amount of
overfeeding of the fabric onto the tenter pins, at the entry end of
the tenter apparatus, to accommodate lateral distension of the
fabric and shrinkage of the fabric in the processing stage, the
supply of fabric to the tenters must be at a rate higher than the
linear rate of travel of the tenter chains -- as much as 20-30
percent higher in the case of some knitted fabrics, for example. To
this end, the speed of the rollers 156, 157, the rollers 166, 167,
and also the brush wheels 168 advantageously are controlled by
adjustable "tach-follower" controls, which enables these elements
to be driven at a predetermined rate relative to the speed at which
the tenter chains are driven. In other words, in order to achieve a
basic overfeed rate of, say, 15 percent, the tach-follower control
for the principal overfeed rollers 156, 157, can be set to operate
at a speed which will correspond to 115 percent of the speed of the
tenter chain drive, and this percentage relationship will be
maintained, even though the operating speed of the tenter chains is
adjusted to a different level.
The overfeed trimming rollers 166 and the related pinning brushes
168 are controlled by separately adjustable tach-follower controls
for separate trimming motors 170 on each side. These separately
controllable tach-followers follow the overfeed rollers 156, 157
and enable a slight "trimming" of the opposite edges of the fabric,
one side relative to the other.
The tach-follower controls are conventionally available, and do
not, in themselves, form part of the present invention. However,
the context in which the controls are employed is of inventive
significance.
Desirably, the input end of the tenter chain is fed on demand by
the padding station 31, and the demand is reflected by the vertical
position of a floating roller 37, which is, in effect, carried by a
loop of the fabric. As this loop shortens, reflecting a reduction
in the running "inventory" of the fabric between the padding
station and the entry end of the tenter chains, the drive equipment
for the padding stage automatically is increased in speed.
In a similar manner, a floating roller 29, measuring an inventory
of fabric between the padding stage 31 and the slitting and opening
stage 23, continuously adjusts the speed of the slitting stage.
At the supply source, a driven roller 22, arranged to draw fabric
from a supply container 20, may be demand-controlled by a dancer
roll 19.
On the discharge side of the processing stage, the folder or
gathering stage 42 is speed controlled by the floating roller 45,
and thus operates in response to the rate at which fabric is
discharged at the de-pinning stage of the tenter.
Advantageously, the draw rollers 236, 237 at the de-pinning stage
are operated by an adjustable tach-follower control which enables
these rollers to be operated at controllable speeds slightly above
or slightly below the tenter chain speed. Thus, if there is a
readjustment in fabric geometry as the fabric is released from the
tenter pins, such readjustment can be reflected by control of the
draw roller speed relative to the tenter chain speed.
In a typical processing of a tubular knitted cotton fabric, for
example, with the system of the invention, the tubular knitted
fabric, typically in a non-uniformly wet form in its as-received
condition from a previous wet processing operation, is drawn out of
the supply container 20 and converted, in the slitting and opening
stage 23, to a flat, open width form. The open width fabric is then
conveyed to the padding stage 31, where the fabric may be
impregnated with a processing solution, such as a "wash and wear"
type resin. If no processing solution is used, the fabric still may
be run through the padding stage and made uniformly wet, as in
accordance with the copending Eugene Cohn et al., application Ser.
No. 625,725, in order that a uniform heat processing action may be
given to the fabric.
The uniformly wetted fabric from the padding stage is advanced to
the entry end of the tenter, where the edges are uncurled, if
necessary, and engaged by the tenter mechanism. The fabric edges
are then advanced, usually, divergently, so that the fabric is
laterally distended somewhat. Thereafter, the fabric is conveyed by
the tenter chains at a predetermined, uniform width. During the
initial portion of the tenter stage, prior to the entry of the
fabric into the processor housing, the fabric is supported at
several places between its edges by the conveyor tapes 198. This
prevents the fabric, which at this point is still wet and heavy,
from sagging and distorting. Inside the pre-heating chamber of the
processor, the fabric is supported by low velocity air flows
directed predominantly upward against the lower surface of the
fabric.
After the fabric passes through the pre-heating chamber, it is
applied to the surface of the processing drum 39 and conveyed about
the main processing chamber. While traveling about the main
chamber, the fabric is at all times engaged at its edges by the
tenter chains and thus held at a precise, predetermined width,
while being fully supported across its entire surface. Being thus
supported, the fabric can be acted upon by very high velocity air
jets, for highly efficient drying or other heat processing and for
advantageous relaxation of the fabric. The fabric is then conveyed
through a post-heating chamber 83, after which the fabric emerges
from the processor housing 46.
Under some circumstances, the fabric may be directed, on a
continuous tenter system, through a second processing stage,
similar to the first, if additional processing capacity is
necessary or desirable because of the nature of the fabric or the
speed of operation of the line. In any event, after the last drying
stage, the fabric advantageously is directed through a cooling
stage 40, following which the fabric is de-pinned, geometrically
re-adjusted if desired, and folded or otherwise gathered. In the
heat setting of polyester fabrics, for example, it may be
advantageous to effect a "shock cooling" of the fabric after heat
processing. In such a case, the cooling stage may include a
refrigeration capacity. Otherwise, cooling is effected by the
circulation of unheated ambient air.
The design and construction of the rotary tenter-processor unit are
of particular importance in that it is possible to achieve reliably
uniform across-the-width processing results in a width-adjustable
rotary processor of practical design. Thus, the apparatus of the
invention utilizes a processor drum of fixed axial length, and
provides full width air nozzles, both in conjunction with the use
of symmetrically adjustable tenter guides. With this arrangement,
the air flows in the critical heat processing area may be properly
balanced and distributed in the first instance and thereafter are
not altered or affected by adjustments in the width of the tenter
facilities. In addition, symmetrical adjustment of the tenter
guides, with reference to the center axis of the processor unit,
not only maintains optimum balance in the air flows through the
fabric, but also enables the fabric to retain its alignment with
other components of an overall processing line.
Extremely efficient and uniform drying, heat setting, curing, or
other heat processing is realized in the apparatus, partly because
of the uniformly distributed high velocity air jets as above
described, partly as a result of the distribution of air flows into
and from the end chambers, blower intake chambers and exhaust
outlets, and also partly as the result of providing an extremely
narrow space between the drum surface and the surrounding air
nozzles to achieve maximum effectiveness of the high velocity air
jets. Overall, this arrangement enables an extraordinarily high
processing capacity to be obtained in a unit of practical size.
The apparatus of the invention is particularly well adapted for,
but not necessarily limited to, the processing of open width
knitted fabric. In this respect, the tenter arrangements include
advantageous facilities for aligning the cross lines of the fabric,
overfeeding of the fabric onto the tenter chains to accommodate
lengthwise shrinkage in the drying process, and facilities for
laterally distending the fabric, prior to processing. All of these
capabilities enable the delivered open width fabric to have an
optimum geometric stability, and also to have a superior appearance
as regards cross line straightness, etc.
In connection with the foregoing, it will be understood that the
requirements of processing a knitted fabric are such that rotary
tenter processors of available designs are not suitable or
applicable to a sufficient extent to be commercially useful in the
processing of knitted fabrics. On the other hand, the requirements
for processing woven fabrics are sufficiently less rigorous that
many of the principles of the present invention may be applied to
commercial advantage in woven goods processing.
An advantageous feature of the system of the invention which
appears to have broad applicability to the tenter handling of
knitted fabrics, and perhaps also certain other types of fabrics,
particularly those which are relatively unstable geometrically, is
the provision of one or more narrow supporting tapes between the
tenter chains. The supporting tapes extend parallel to the tenter
axis, and typically are disposed substantially in the plane defined
by the spaced tenter chains. Accordingly, when the fabric is
gripped at its edges and conveyed by the tenter chains, the central
areas of the fabric are supported against sagging.
More importantly, the supporting tapes associated with the tenter
chains, are arranged to be driven at a speed which differs from the
speed of the tenter chains themselves, typically, the tapes are
driven at a slightly higher speed. This provides for an
advantageous measure of cross line straightness control, which is
particularly effective where a variable speed relationship is
provided for between the supporting tapes and the tenter chains.
Particularly where cross line control is important, as in the
handling and processing of knitted and other distortable fabrics,
it is significant that the arrangement of the supporting tapes be
such as to support principally the central areas of the fabric, so
that speed differentials between the supporting tapes and the
tenter chains will have the effect of adjusting the center region
of the fabric relative to its edges.
Various features of the invention, including but not limited to the
tach-follower controls, combine to provide for an optimum control
over the manipulation of the fabric throughout, to keep the fabric
free of distortions and otherwise of a high finished quality. Among
these features are the described arrangement for driving the tenter
chains in linear synchronism, the constant-length flexing sections
at the entry end of the tenter section, the separately adjustable
overfeed trimming controls, and the like.
As will be observed, in the method and apparatus of the invention,
the knitted or other fabric web being processed is contacted on one
surface only. This is particularly desirable in the case of certain
"sensitive" fabrics, such as cotton velours, for example, where it
is very important to maintain one side substantially free of
pressure contact with other surfaces throughout the processing
operations.
In the system of the invention, where the fabric to be processed
initially is in tubular form, it may be desirable to apply a
gumming composition to the fabric, so that a narrow margin of the
composition extends along the short edges of the fabric,
advantageously just outside the tenter pins. After processing, the
gummed edges may be trimmed off, as by suitable slitters located in
advance of the batching stage. It may also be advantageous to
incorporate steaming stages in the processing line, so that the
fabric may be steamed before and/or after heat processing, as may
be desirable or expedient.
It should be understood, of course, that the specific form of the
invention herein illustrated and described is intended to be
representative only, as certain changes may be made therein without
departing from the clear teachings of the disclosure. Accordingly,
reference should be made to the following claims in determining the
full scope of the invention.
* * * * *