CA1086972A

CA1086972A - Weft knitted raschel-like thermal fabric, and method of knitting the same

Info

Publication number: CA1086972A
Application number: CA316,074A
Authority: CA
Inventors: John E. Morgan
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-11-09
Filing date: 1978-11-09
Publication date: 1980-10-07

Abstract

WEFT KNITTED RASCHEL-LIKE THERMAL FABRIC, AND METHOD OF KNITTING THE SAME

Abstract A weft knitted thermal fabric simulating raschel thermal fabric in appearance and in heat insulating property.
The fabric has a multitude of air-entrapping cells formed on at least one side to provide dead air spaces, thereby giving the fabric an enhanced heat retention quality. The air-entrapping cells are three dimensional cavities defined by spaced side walls and spaced top and bottom walls. Each wall 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.
The air-entrapping cells are provided with floors composed of a knitted wale formed of alternating tuck loops and knitted stitches. The fabric is knit on a 1 x 1 rib knitting machine operated in alternating repeat sequences to produce knitted stitches, floats and tuck loops selectively in the fabric, to provide successive rows of air-entrapping cells, with the cells of each row staggered relative to the cells of the next adjacent rows.

Description

6g'72 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 ~36~72 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 . ~
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 - 5a -D

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~:)8~972 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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~08~972 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 ~69~;~

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 _g _ '~ ,. ~.; , )86~

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 ;97~

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:

,, ' , . , ~: , 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 ; -13-. .
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69~72 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 . .. ' ' , ,, ,. . ~ :. .: .

`` lL~1~36~72 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 . : . . ~ . . ..

g~z 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.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A weft knitted thermal fabric simulating raschel thermal fabric in appearance and in heat insulating property, said weft knitted fabric being formed of courses and wales, being formed of relatively 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 intermediate 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.

2. The weft knitted thermal fabric of Claim 1, wherein the air-entrapping cells are formed on both sides of the fabric.

3. The weft knitted thermal fabric of Claim 2, wherein the fabric comprises a circular rib knitted fabric.

4. The weft knitted thermal fabric of Claim 3, wherein the fabric comprises a 1 x 1 rib knitted fabric.

5. The weft knitted thermal fabric of Claim 4, wherein the fabric comprises a tight knit fabric made on a circular rib body size knitting machine.

6. 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 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 gauge 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 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.

7. The thermal fabric of Claim 6, wherein the air-entrapping cells are disposed in staggered relation, and wherein the fabric includes:
(a) a first group of plural courses in which alternating courses are formed into knitted stitches in alternate wales and into floats and tuck loops in the intervening wales, said floats and tuck loops being disposed in course-wise extending alternating sequence, and the inter-vening courses are formed into knitted stitches in the intervening wales and into tuck loops and floats in the alternate wales, said tuck loops and floats being disposed in course-wise extend-ing alternating sequence, and (b) a second group of plural courses in which alternating courses are formed into knitted stitches in the alternate wales and into tuck loops and floats in the intervening wales, said tuck loops and floats alternating in reverse sequence to their sequence in the alternating courses in the first group of plural courses, and the intervening courses are formed into knitted stitches in the intervening wales and into floats and tuck loops in the alternate wales, said floats and tuck loops alternating in reverse sequence to their sequence in the plurality of intervening courses in the first group of plural courses.

8. The thermal fabric of Claim 7, wherein the first group and second group of courses are repeated in alternating sequence in the fabric.

9. A method of forming yarns into the weft knitted raschel simulated thermal fabric of Claim 2 on a knitting machine having opposed needle banks, including the steps:
(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 intervening 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 (c) 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 fabric alternating in reverse sequence 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.

10. The method of Claim 9, further including the steps of alternately repeating said first plurality of alternate and intervening courses and said second plurality of alternate and intervening courses.

11. The method of Claim 10, in which the needles of said needle banks are positioned to knit a 1 x 1 rib knit fabric.

12. The method of Claim 11, further including knitting the fabric on a coarse gauge body size circular rib knitting machine having a dial and a cylinder each provided with a plurality of independent needles, and forming the fabric of plural relatively heavy yarns knit under relatively heavy tension to produce a tight knit fabric.

13. The method of Claim 12, further including the steps of removing the fabric from the knitting machine, subjecting the fabric to a process involving wetting the fabric and then subjecting the fabric to tumble drying at an elevated temperature.

14. A method of forming a weft knitted raschel simulated thermal fabric of claim 6 on a rib knitting machine having opposed needle banks, said weft knitted fabric being formed of courses and wales and having plural air-entrapping cells formed on at least one side, including the steps:
(a) knitting from yarn a first cycle of plural courses of fabric, and while knitting said first cycle, knitting a plurality of alternating courses, with the needles of one needle bank producing knitted stitches and with the needles of the opposed needle bank operating to produce floats and tuck loops in alternating sequence in the fabric, and knitting a plurality of intervening courses, with the needles of the first mentioned needle bank operating to produce tuck loops and floats in alternating sequence in the fabric and the needles of the second mentioned needle bank producing knitted stitches, and (b) knitting from yarn a second cycle of plural courses of fabric, and while knitting said second cycle, knitting a plurality of alter-nating courses, with the needles of the first mentioned needle bank producing knitted stitches and with the needles of the second mentioned needle bank operating to produce tuck loops and floats in the fabric alternating in reverse sequence to their sequence in the plurality of alternating courses in the first cycle, and knitting a plurality of intervening courses, with the needles of the first mentioned needle bank operating to produce floats and tuck loops in the fabric alternating in reverse sequence to their sequence in the plurality of intervening courses in the first cycle and the needles of the second mentioned needle bank producing knitted stitches, and (c) alternately repeating the knitting of said first cycle of courses and said second cycle of courses.