Note: Descriptions are shown in the official language in which they were submitted.
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Definitions
The following definitions shall be applicable herein:
The term "air-entrapping cell" indicates a three
dimensional cavity formed in a fabric to provide dead air space,
to give the fabric an enhanced heat retention quality.
The terms "thermal fabric" and "heat insulating fabric"
are synonymous, and indicate a fabric designed to trap and
retain air warmed by the heat of the human body, by the pro-
vision of a multitude of air-entrapping cells formed in the
fabric.
The terms "stitch" and "knitted stitch" are synonymous,
and indicate a loop of yarn which has been pulled through a
preceding yarn loop.
The term "casting off" indicates the discharge of
a loop of yarn from a needle, as a newly drawn loop of yarn
is pulled through the discharged loop to form a new stitch.
The term "cast-off level" indicates the lowest level
to which a needle descends in casting off a stitch or yarn
loop.
The term "clear level" indicates the level to which
a needle rises, or has risen, to clear yarn from its latch,
preparatory to receiving a new yarn in its hook.
The term "tuck level" indicates the level to which
a needle rises to receive a new yarn in its hook while retaining
a loop of yarn on its latch.
The term "tuck loop" indicates a loop of yarn which
has not been pulled through a preceding yarn loop, but has
been cast off with a succeeding yarn loop.
The term "welt level" indicates the relatively low
level to which a needle descends, or has descended, whereby
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it is too low to receive yarn in its hook, thereby producing a
yarn float in the fabric.
The terms "course-wise" and "course-wise extending"
are directional terms indicating the "horizontal" dimension
extending along a course of a knitted fabric.
The terms "wale-wise" and "wale-wise extending" are
directional terms indicating the "vertical" dimension extending
along a wale of a knitted fabric.
The term "coarse gauge" applied to a knitting machine
indicates a machine falling within the range of an 8 cut to
12 cut circular knitting machine, or its equivalent.
The term "body size" applied to a knitting machine
indicates a circular knitting machine in which the needle
cylinder has a diameter falling within the range of 12" to 17".
The term "relatively heavy yarn" indicates a yarn
falling within the range of a No. 12 to No. 16 single cotton
yarn or single blended cotton and synthetic yarn, or any yarn
which is the equivalent thereof.
Background of the Invention
Thermal fabric is a specific category of fabric for
garments designed for cold weather wear, distinguished by a
multitude of air-entrapping cells formed in the fabric. The
air-entrapping cells are three dimensional cavities having
spaced top, bottom and side walls and a floor, which trap
and retain air warmed by the heat of the human body. The
cells give the fabric an enhanced heat insulating or heat
retention quality. Such fabrics are used primarily in the
manufacture of therma~~ underwear for winter wear, although
they also have found use inthe manufacture of other types of
products, such as sweaters, socks, blankets and the like.
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The original thermal fabric, first known as "waffle
knit" fabric, was developed by the United States Navy for
military use in about 1951. The Navy's waffle knit fabric is
a flat, warp knit fabric made on a double needle bar raschel
knitting machine. It soon found acceptance for civilian use
in underwear, and became known popularly as "thermal underwear".
A great interest arose in the underwear industry for
developing a competing weft knit thermal fabric which could
be made on conventional circular knitting machines. Raschel
knit thermal underwear is relatively expensive to manufacture,
and because of the limited number of raschel knitting machines,
supplies of the new fabric were limited. A weft knit thermal
fabric eventually was developed, and patented under Morgan
United States patent No. 2,839,909. The Morgan patented
fabric is made on an 8 feed circular rib knitting machine
having dial and cylinder needles disposed in a 2 x 2 rib
knitting arrangement. The air-entrapping cells of this fabric
are produced by alternate triple tucking, first on one set of
needles, then on the other set of needles, the non-tucking
needles knitting plain stitches. The fabric is characterized
by tuck strands extending across the valleys formed between
the ribs of the fabric, the ribs forming the side walls of the
air-entrapping cells and the tuck strands forming the top and
bottom walls of the cells.
In or about 1967, a second type of circular weft kni.t
thermal fabric was developed, by The Singer Co., utilizing its
Philip Model PT/RR knitting machine. The PT/RR machine is a
48 feed, 33" cylinder 1 x 1 rib circuLar rib knitting machine
using the flexer principle to rack the dial needles. The
machine is arranged for knitting a full cardigan fabric, and
selective racking of the dial needles is utilized, whereby the
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needles assume a 2 x 2 rib relationship during knitting of
the fabric. The Singer PT/RR therma] fabric is the subject of
Philip United States patent No. 3,56~,475. Because the air-
entrapping cells in succeeding rows in the Singer thermal fabric
are staggered, the fabric more nearly simulates the raschel
thermal fabric in appearance than does the earlier Morgan
patented thermal fabric.
While the Morgan weft knit thermal fabric has enjoyed
significant commercial success, the Singer PT/RR thermal fabric
apparently has met with only limited acceptance. This is due,
apparently, because of the large size of the needle cylinder
of the PT/RR knitting machine, and the complications inherent
in the operation of knitting machines utilizing the flexer
principle. Additionally, the Morgan patented thermal fabric,
which is made on body size machines, is more economical to cut
and sew into underwear and other garments, than the Singer
PT/RR fabric made on large diameter knitting machines.
Summary of the Invention
The primary object of this invention is to provide
a new and improved weft knitted heat insulating fabric which
simulates raschel thermal fabric in appearance and in heat
retention property, and which is more economical of manufacture
into thermal underwear and other ~arments than have been fabrics
heretofore developed.
A further object of this invention is to provide a
new and improved weft knit thermal fabric having maximum
quality in insulating value with a minimuTn of weight.
To this end the invention consists of a weft knitted
thermal fabric simulating raschel thermal fabric in appearance
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and in heat insulating property, said weft knitted Eabric
being formed of courses and wal~s, being formed of relatively
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heavy yarn knitted under relatively heavy tension on a
coarse gauge knitting machine and having plural air-entrapping
cells formed on at least one side, wherein: (a) the cells
are disposed in a plurality of successive rows extending
course-wise across the fabric, (b) the cells of each row are
staggered relative to the cells of the next adjacent rows,
(c) each cell extends course-wise and wale-wise of the
fabric, and has spaced side walls and spaced top and bottom
walls, which define the cell, and a floor disposed inter-
mediate the walls, (d) each wall of the cells comprises .:
elevated fabric formed of two separate, closely spaced,
wale-wise extending, ribs of knitted stitches, the stitches
of the two ribs being connected and drawn together by yarn
floats, and (e) the floor of each cell includes a wale of
alternating tuck loops and knitted stitches.
The invention also provides a weft rib knitted
thermal fabric simulating raschel thermal fabric in appearance
and in heat insulating property~, said fabric having plural ::
air-entrapping cells formed on at least one side, said cells
2~ being constituted by spaced side walls, spaced top and bottom
walls and a floor disposed intermediate said walls, wherein:
(a) the fabric is a tight knit fabric formed of relatively
heavy yarn knitted under relatively heavy tension on a coarse
guage body size knitting machine, (b) the fabric is composed
of alternating and intervening courses, the alternating
courses being formed into knitted stitches in alternate
wales and into alternating floats and tuck loops in the
intervening wales, and the intervening courses being formed
into knitted stitches in the intervening wales and into
alternating floats and tuck loops in the alternate wales,
(c) each wall of the cells comprises elevated fabric formed
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of two separate, closely spaced, wale-wise extending ribs of
knitted stitches, the stitches of the two ribs being
connected and drawn together by yarn floats, and (d) the
floors of the cells are constituted by wales of alternating
tuck loops and knitted stitches.
The invention also consists of forming such a
fabric by means of the steps of (a) knitting a first plurality
of alternate courses with the needles of one of the needle
banks being operated to produce knitted stitches and with
the needles of the opposed needle~bank being operated to
produce floats and tuck loops in alternating sequence in
the fabric, (b) while knitting a first plurality of inter-
vening courses with the needles of the first mentioned
needle bank being operated to produce floats and tuck loops
in alternating sequence in the fabric and with the needles of
the second mentioned needle bank being operated to produce
knitted stitches, and (c2 then knitting a second plurality
of alternate courses with the needles of the first mentioned
needle bank being operated to produce knitted stitches and
with the needles of the second mentioned needle bank being
operated to produce tuck loops and floats in the fabric
alternating in reverse sequence! to their sequence in the
first plurality of alternate courses, (d) while knitting a
second plurality of intervening courses with the needles of
the first mentioned needle bank being operated to produce tuck
loops and floats in the fa~ric alternating in reverse se-
quence to their sequence in the first plurality of intervening ,
courses and with the needles of the second mentioned needle
bank being operated to produce knitted stitches.
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Other features will be apparent from the followingdescription of a preferred embodiment of the invention,
reference being had to the accompanying drawings. -
Description of the Views of the Drawing
Fig. 1 is a photograph of one side of a preferred
knitted thermal fabric incorporating this invention, en-
larged approximately four times.
Fig. 2 is an enlarged, fragmentary view illustrating
schematically the fabric depicted in Fig. 1.
Fig. 3 is a knitting diagram showing the operation
of the cylinder and dial needles in knitting successive
courses of the fabric illustrated in Fig. 1 on a 1 x 1
circular rib knitting machine.
Fig. ~ is a diagrammatic view of the fabric
illustrated in Fig. 1 on a greatly enlarged scale, showing
the stitch structure thereof.
Detailed Desc_iption of *he Preferred Embodiment
Figs. 1, 2 and 4 depict the preferred weft knit
thermal fabric of this in~rention. rrhe fabric is characterized
by the provision of a multitude of individual air-entrapping
cells formed on both sides of the fabric. rrhe cells are
disposed in a plurality of successive rows extending course-
wise across the fabric, with the cells of each row staggered
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relative to the cells of the next adjacent rows. While it is
preferred that the air-entrapping cells be formed on both sides
of the fabric, it is within the scope of this invention to
provide a thermal fabric having air-entrapping cells formed
on one side only.
Referring specifically to Fig. 2, where the fabric
20 is shown schematically, there are illustrated successive
rows 22, 23, 24, 25, 26 of plural course-wise extending air-
entrapping cells 30. The cells 30 are defined by course-wise
spaced side walls 31, 32 and wale-wise spaced top walls 33
and bottom walls 34. Each wall 31, 32, 33, 34 comprises
elevated fabric formed of two separate, closely spaced, wale-
wise extending ribs of plural knitted stitches, the stitches of -
each two such juxtaposed ribs being connected and drawn
together by yarn floats. The side walls 31, 32 actually may
be identical for side by side cells 30, in that side wall 31
of any particular cell also comprises the side wall 32 of one
of its next adjacent cells, and vice-a-versa. Each bottom
wall 34 is located proximate the point where its two juxtaposed
ribs begin to diverge, and each top wall 33 is located proxi-
mate the point where its two juxtaposed ribs have converged to
close the top of the cell. Each cell is provided with a floor
35 disposed intermediate the spaced side, top and bottom walls.
The fabric shown in the drawing comprises a 1 x 1
rib knitted fabric, made on a multi-feed knitting machine
having opposed needle banks. Preferably, the needles are
independently mounted on each of the needle banks with capacity,
utilizing well known and conventional needle selecting means,
to be raised and lowered selectively to clear level, tuck level,
welt level and cast-off level, to produce rib knitted fabric
incorporating stitches, tuck loops and floats in any predetermined
:
manner. Relatively heavy yarns are fed to the needles of the
machine and are knitted under relatively heavy tension at
each of the yarn feeds, to produce a tight knit fabric,
thereby enhancing the depth of the air-entrapping cells
produced in the finished abric.
A suitable knitting machine for producing the thermal
fabric depicted in the drawing is the Albi ROFS I multi-feed,
coarse gauge, body size circular rib knitting machine. The
Albi machine is provided with a single cylinder and a single
dial, each incorporating a plurality of independent needles
alternating in a 1 x 1 rib arrangement. Both the cylinder
and dial needles are relatively heavy, each being provided with
24 gauge hooks. Positive yarn feeding means are utilized,
such as furnishing wheels, to feed yarn to the needles at
each of the yarn feeds at a selected rate of feed. The machine
preferably is equipped with 16 yarn feeds, and a 10 cut machine
is preferred.
Positive yarn feeding devices are utilized to meter
the yarn fed to the needles to ensure that the yarn is knit
under relatively heavy tension to produce a tight knit fabric.
By way of example, where a No. 12 single cotton yarn is uti-
lized, the fabric is knit with approximately 16 stitches per
inch, prior to finishing of the fabric. Where a No. 16 single
cotton yarn is utilized, approximately 17 stitches per inch
are knit in the fabric prior to finishing.
Fig. 3 shows a preferred sequence for knitting the
fabric of this invention on a 16 feed circular knitting
machine provided with a needle cylinder and needle dial, with
the needles arranged for knitting a 1 x 1 circular rib fabric.
The vertical columns denoted C and D refer, respectively, to
individual needles mounted on the cylinder and on the dial of
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of the machine. The horizontal rows numberedl, 2, 3, etc. to
16 identify consecutive yarn feeds spaced at intervals around
the needle cylinder of the knittlng machine. As is well under-
stood in this art, the yarns fed at each of the yarn feeds 1,
2, 3, etc. produce a separate course in the fabric being knit.
The letter K identifies a knitted stitch, and the letter T
indicates a tuck loop. The letter W indicates where a float
is formed in the fabric when a needle is retained at welt
level. The designations HB and LB indicate, respectively,
utilization of needles having high butts and low butts for
purpose of needle selection.
As the knitting diagram of Fig. 3 illustrates, during
the knitting of the first cycle of 8 courses of the fabric, at
yarn feeds 1 to 8 inclusivej the following takes place. At
yarn feeds 1, 3, 5 and 7, all of the dial needles produce
knitted stitches. Alternate cylinder needles are lowered to
welt level to produce floats in the fabric, while the inter-
vening cylinder needles are tucked to produce tuck loops.
Meanwhile, at yarn feeds 2, 4, 6 and 8, the cylinder needles
produce knitted stitches, alternate dial needles produce tuck
loops and the intervening dial needles are welted to produce
yarn floats.
During the knitting of the second cycle of 8 courses,
at yarn feeds 9 to 16 inclusive, the knitting sequence is
modified. At yarn feeds 9, 11, 13 and 15, all dial needles
continue to produce knitted stitches, but the cylinder needles
are operated in reverse sequence. Alternate cylinder needles
are tucked to produce tuck loops, while the intervening cylin-
der needles are welted to produce yarn floats. At yarn feeds
10, 12, 14 and 16, the cylinder needles continue to form
knitted stitches, but the dial needles operate in reverse
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sequence, with the alternate dial needles welting to produce
yarn floats and the intervening dial needles producing tuck
loops.
The knitting of yarn at feeds 1 to 8 inclusive
represents a first cycle of knitting, producing in the fabric
(Fig. 2) a course-wise extending row 22 of air-entrapping
cells 30. The knitting of yarn at feeds 9 to 16 represents
a second cycle of knitting, producing in the fabric a second
course-wise extending row 23 of air-entrapping cells 30, with
the cells of the second row staggered relative to the cells
of the first row. The two cycles of knitting are repeated
alternately in the knitting of the fabric, to produce a
plurality of succeeding course-wise extending rows 22-26 of
air entrapping cells 30. Each cycle of 8 courses produces
one row of air-entrapping cells, the cells of each row being
; staggered relative to the cells of the next adjacent rows.
Fig. 4 illustrates diagrammatically the stitch
structure of the fabric produced in accordance with the
knitting sequence illustrated in Fig. 3. In Fig. 4, the
numerals l' to 16' inclusive designate courses in the fabric,
and correspond to the yarn feeds 1 to 16 in Fig. 3. The
letters C' and D' denote, respectively, the cylinder needle
wales and dial needle wales of the fabric. The reference
letters _, b, c, etc. identify, respectively, the yarns fed
at yarn feeds 1, 2, 3, etc. to produce courses 1', 2', 3',
etc. in the fabric. The relationship between the yarn feeds
of Fig. 3 and the individual yarns depicted in Fig. 4 is as
follows:
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Yarn Feed Yarn Yarn Feed ~arn
1 a 9
2 b 10 J
3 c 11 k
4 d 12
e 13 m
6 f 1~ n
7 ~ 15 o
8 _ 16
It will be observed from Fig. 4 that, in courses 1'
to 8' of the fabric, alternate yarns a, c, e and ~ are formed into
knitted stitches in dial needle wales D', into floats F in
alternate cylinder needle wales C' and into tuck loops T' in
the intervening cylinder needle wales C'. Intervening yarns
b, d, f and h are formed into knitted stitches in the cylinder
needle wales C', into tuck loops T' in àlternate dial needle
wales D', and into floatsF in the intervening dial needle
wales D'.
In courses 9' to 16', alternate yarns i, k, m and o
also are formed into knitted stitches in the dial needle wales
D'. However, those yarns are formed into tuck loops T' in the
alternate cylinder needle wales C' and into floats F in the
intervening cylinder needle wales C'. Intervening yarns i, 1
n and p also are formed into knitted stitches in the cylinder
needle wales C'. But those yarns are formed into floats F in
the alternate dial needle wales D' and into tuck loops T' in
the intervening dial needles D'.
Thus, the fabric depicted in Fig. 4 is composed of
alternating cycles or groups of courses 1' to 8' and 9' to 16'.
In each first group of courses 1' to 8', the yarns in the
alternate courses 1', 3', 5', 7' are formed into knitted
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stitches in the dial needle wales D' and into floats F and tuck
loops T' in alternating sequence in the cylinder needle wales
C'. In the intervening courses 2', 4', 6', 8', the yarns are
formed into tuck loops T' and floats F in alternating sequence
in the dial needle wales D' and into knitted stitches in
cylinder needle wales C'.
In each second cycle or group of courses 9' to 16',
the yarns in the alternate courses 9', 11', 13', 15' are
formed into knitted stitches in the dial needle wales D' and
into tuck loops T' and floats ~ in the cylinder needle wales
C'. In the latter wales, however, the tuck loops T' and
floats F alternate in reverse sequence to their sequence in
the alternating courses 1', 3', 5', 7'. The yarns in the
intervening courses 10', 12', 14', 16' are formed into floats
F.and-tuck loops T' in the dial cylinders D', but the floats
F and tuck loops T' alternate in reverse sequence to their
sequence in the intervening courses 2', 4', 6', 8'. The
yarns in the cylinder needle wales C7 in the intervening
courses 10', 12', 14', 16' are formed into knitted stitches.
It will be understood that the two groups of courses
1' to 8' and 9' to 16' are knitted in alternating cycles
during formation of the fabric on the knitting machine.
The floats F are disposed wale-wise of the fabric
in spaced groups of four floats each, separated by spaced
groups composed of four tuck loops T' in the same wale. The
wale-wise spaced groups of floats F and tuck loops T' in the
dial needle wales D' are staggered relative to the wale-wise
spaced groups of floats F and groups of tuck loops T' in the
cylinder need:Le wales C'.
Because the fabric is tightly knit under relatively
heavy tension from relatively heavy yarns on a coarse gauge
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knitting machine, the floats formed in the fabric tend to draw
together the two course-wise spaced knitted stitches which
they connect. As a result, the spaced ribs formed in the
dial needle wales D' are pulled together in the fabric areas
where their stitches are connected by floats F, to produce
elevated fabric forming the walls defining the air-entrapping
cells on the dial face of the fabric. Similarly, the spaced
ribs of fabric formed in the cylinder needle wales C' are
pulled together in the fabric areas where their stitches are
connected by floats F, to produce elevated fabric forming the
walls defining the air-entrapping cells on the cylinder face
of the fabric.
Fig. 4 shows the dial face of the fabric, and it will
be assumed that Fig. 2 also depicts the dial face of the fabric.
In Fig. 2, the areas where the ribs appear contiguous and form
the side walls 31, 32 represent the areas of the fabric where
the stitches of adjacent dial wales are connected, and drawn
together, by the yarn floats F. Where the wale-wise succession
of floats F terminate, the closely spaced or juxtaposed
stitches in the dial wales begin to diverge, to form the bottom
and top walls 34, 33, respectively, of the air-entrapping cells
30. Between the side walls 31, 32 and the top and bottom walls
33, 34 of the air entrapping cells 30, the floors 35 of the
cells are constituted by a cylinder needle wale consisting of
- alternating tuck loops T' and knitted stitches.
The appearance and construction of the fabrics
depicted in Figs. 1, 2 and 4 preferably are identical on both
sides of the fabric. Thus, on the cylinder needle side of
the fabric, the walls of the air-entrapping cells are defined
by elevated fabric formed of two separate, wale-wise extending,
ribs of cylinder needle stitches drawn together in spaced
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locations by yarn floats. The floors of those cells are
constituted by dial needle wales composed of alternating tuck
loops and knitted stitches.
As pointed out previously, any well known, conven-
tional needle selection means may be utilized to manipulate
the needles, during knitting of the fabric, to produce knitted
stitches, tuck loops and floats in accordance with the knitting
pattern illustrated in Figs. 3 and 4. One preferred needle
selecting arrangement is to utilize, in boththe dial and the
cylinder of the knitting machine, alternating low butt and
high butt needles, disposed in the following manner:
Dial Needles LB / HB / LB / HB /
..... repeat
Cylinder Needles LB / HB / LB / HB /
Referring back to Fig. 3, it will be observed that
at yarn feed 1 both the low butt and the high butt dial needles
are operated to produce knitted stitches, whereas the low butt
cylinder needles are welted to produce yarn floats and the
high butt cylinder needles are tucked to produce tuck loops.
The same needle manipulations take place at yarn feeds 3, 5
and 7.
At yarn feed 2, both the low butt and the high butt
cylinder needles are operated to produce knitted stitches. At
the same time, the low butt dial needles are welted to produce
~ yarn floats and the high butt dial needles are tucked to
; produce tuck loops. These same needle manipulations take
place at yarn feeds 4, 6 and 8.
The same type of needle manipulations occur at yarn
feeds 9-16. But at feeds 9, 11, 13 and 15, in reverse sequence
to their operation at feeds 1, 3, 5, 7, the low butt cylinder
needles are tucked to produce tuck loops and the high butt
cylinder needles are welted to produce yarn floats. At feeds
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10, 12, 14 and 16, in reverse sequence to their operation
at feeds 2, 4, 6, 8, the low butt dial needles are tucked to
produce tuck loops and the high butt dial needles are welted
to produce yarn floats.
The dial and cylinder camming for the foregoing
needle manipulations is a matter of common and general knowledge
in the art. The selection of the necessary high and low butt
dial and cylinder camming to accomplish the sequence of knit-
ting illustrated in Figs. 3 and 4 will be obvious to one
skilled in the art, and its detailed description therefore is
unnecessary.
After the fabric of the invention has been knitted
and removed from the knitting machine, it may be subjected to
the usual post-knitting finishing operations, including scouring,
dyeing and drying. In the case of fabrics knit from cotton
yarns, tumble drying of the wet fabric at temperatures on the
order of 225F is desirable to ensure a tight knit, suitable
heat insulating fabric. Where blended yarns are utilized,
such as cotton-polyester mixtures, tumble drying preferably is
not utilized. With fabrics knit of such yarns, a conventional
drum dryer may be employed at temperatures on the order of
300F. Following drying, the fabric may be napped, if desired,
and also subjected to shrinkage control utilizing the well
known Tube-Tex tensionless calender.
Finished fabrics knit of No. 12 single cotton yarn,
or its equivalent, preferably are finished to a weight of about
9 ounces per square yard and to a stitch density of approxi-
mately 22 stitches per inch. Fabrics knitted of No. 16 cotton
yarn, or its equivalent, preferably are finished to a weight
of about 7 ounces per square yard and to a stitch density of
approximately 23 stitches per inch.
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Although a preferred embodiment of this invention
has been shown and described for the purpose of illustration,
it is to be understood that various changes and modifications
may be made therein without departing from the spirit and
utility of this invention, or the scope thereof as set forth
in the appended claims.
