US3820358A - Apparatus for knitting pile fabric - Google Patents

Abstract

Discrete fibers arranged in a continuous and cohesive length, preferably in the form of a roving or loosely spun yarn are fed to the needles of a circular knitting machine through a yarn guide tube. The roving or loosely spun yarn is engaged by the hooks of the needles. The roving or loosely spun yarn is then disrupted by brushing which causes the fibers to be reformed from a continuous length of fibers into individual tufts with each tuft engaged by a needle. Thereafter a backing yarn is fed to the needles and the yarn and tufts are knitting into a pile fabric with the pile on one side of the backing yarn.

Description

' Frishman APPARATUS FOR KNITTING PILE FABRIC 1451 June 28, 1974 Primary Examiner-Robert R. Mackey [57] ABSTRACT I Discrete fibers arranged in a continuous and cohesive ing yarn isfedto the needles and the yarn and tufts are knitting into a pile fabric withthe pile on one side vof the backing .yarn.

2 Claims, 6 Drawing Figures [76] Inventor: Daniel Frishman, 14 Castle Heights Rd., Andover, Mass. 01810 [22] Filed: June 19, 1972 [21] Appl. No.: 263,976

[52] US. Cl.'.....' 66/9 B [51] Int. Cl D04b 9/14 [58] Field of Search 66/9 B, 80, 9 R

[56] References Cited UNlTED STATES PATENTS 3,l24,944 3/1964 Bond et al 66/9 R SHEEI 1 [IF 2 I PATENTEBJIINZB m4 APPARATUS FOR KNITTING PILE FABRIC BACKGROUND OF INVENTION method frequently requires the use of additional yarn to hold the pile yarn. This in turn results in a fabric which contains relatively more backing and less pile with a consequent loss of flexibility. ln addition, such manufacturing techniques require subsequent napping steps which is a costly process that requires careful control and skill. Napping operations of this type also result in some fiber breakage as well as a fabric that has some excessively long fibers and a residue of yarn that have unopened portions near the base of the fabric. Such unopened yarns contribute little or nothing to the pile texture of the material.

In another method of manufacturing knitted pile fabrics slivers are knitted intoa fabric backing. Such a sliver knitting technique or method results in a pile fabric which does not require napping and which has excellent drape characteristics. Such sliver knit pile fabrics, moreover, are fur-like in that random lengths of fiber in the pile simulate to some extent the natural conditions found in the real furs. However, even sliver knitting has some disadvantages. In this process, the

slivers are fed to the needles of a knitting machine by small cards mounted on'the knitting machine. These small cards must be frequently adjusted and maintained in order to assure a uniform delivery of sliver to the knitting machine. Unfortunately it is substantially impossible to be certain that these small cards are always maintained in precise adjustment. As a result the slivers are frequently fed non-uniformly to the knitting machine. This in turn results in an uneven weight distribution of the pile in the knit fabric. The existence of this uneven weight distribution is highlighted and emphasized by finishing processes which include the imparting of luster to the fabric in heat and pressure treatments. Since the uneven distribution of the pile is ordinarily not random the end product often has streaks of pile that are non-uniform. Such streaks of non-unifonn pile may limit the value of the product being manufactured.

One further disadvantage of sliver knitting tech niques is the relevant inefficiency of the method with respect to the number of feeds. In certain practice no more than eight cards and feeds may be used on a knitting machine which is 23 to 24 inches in diameter. This limitation is defined by the size of the cards. Such a limitation in turn means that only eight courses may be knitted per revolution of the needle cylinder.

SUMMARY OF INVENTION It is an object of the present invention to overcome the limitations referred to above. Accordingly, it is an object of the present invention to provide an improved and efficient means and method of knitting pile fabric in which a plurality of discrete fibers arranged in a continuous cohesive elongated assembly of fibers, such as for example as in the form of a roving or loosely spun yarn is fed directly to hooks of the circular knitting machine needles to be knitted into the fabric being formed as a pile. While the assembly is engaged by the needles it is disrupted by brushing so that the individual fibers are separated into tufts that are each hooked onto separate needles. Immediately thereafter a backing yarn is fed to the hooks and by appropriate cam action the pile fabric is knit with the tufts forming the pile. The end product is a more uniform version of a conventionally made sliver knit pile fabric. h

It is also an object of the present invention to provide a method for knitting pile fabric in which the use of cards is eliminated and in which fibers in the form of a continuous roving or loosely spun yarn is fed directly to the hooks of the needles.

A further object of the present invention is to provide an improved method of eliminating the streaks that often appear in pile fabrics knit by a sliver knitting technique. A further object of the present invention is to provide a means and method of knitting a pile fabric on a circular knitting machine at speeds not possible with techniques that require the use of individual cards 1 for feeding fibers that are to be formed as the pile. An-

other object of the present invention is to provide a method of feeding sufficient fibers tothe needles of a circular knitting machine to assure the formation of controlled and thick piles.

Another object of the present invention is to' provide an improvedmeans for feeding loosely'spun yarn or roving to-the knitting needles in a positive fashion and in a manner' which eliminates possible malfunctions that would otherwise occur in the event that the roving or loosely spun yarn broke or was separated. One further-object of the present invention is to provide an improved means and method of separating the fibers in the loosely spun yarn orroving as it is being brushed in the needles of the circular knitting machine. A further object of the present invention is to provide a simplified system for knitting pile fabric utilizing simple and easily maintained equipment to produce a pile fabric of a greater uniformity, especially in light-weight fabrics, than heretofore possible. One further object of the present invention is to provide a means and method for knitting pile fabric in which fibers shorter in length than those conventionally used in sliver knitting may be used. In this connection sliver knittingrequires fibers having a minimum length of approximately 1 inch. By utilizing the present invention pile fabric may be knit using fibers of, for example, in the order of if; of an inch in length thus permitting a pile having a height of $6 of an inch, with a minimum of loss during shearing in subsequent finishing operations. Under conventional knitting techniques using sliver methods there would be a greater loss in the fiber due to required shearing to reduce the pile to a if; inch height. Such shearing loss is minimized in the present technique thus effectively saving fiber material.

One further object of the present invention is to provide a method by which the weight of fiber roving or spun yarn required to knit the pile fabric of a given weight may be readily determined thus providing a more effective knitting process.

BRIEF DESCRIPTION OF DRAWINGS The foregoing objects and advantages of the present invention will be more clearly understood when consid- 3 ered in conjunction with the accompanying drawings in which:

FIG. 1 is a diagrammatic plan view of knitting machine with a plurality of feed stations and brushes;

FIG. 1A is a somewhat schematic cross-sectional elevation of a detail of a circular knitting machine illustrating the needle engaging brush used in conjunction with the present invention and taken along the line lA-lA of FIG. 1;

FIG 2 is an enlarged view taken substantially along the line 22 of FIG. 1A and showing a small section of the needle cylinder with the adjacent brush;

FIG. 3 is a cross-sectional view taken along the line 3 3 of FIG. 2;

FIG. 4 is a cross-sectional detail of a modification of the invention taken substantially along the same line as line 2-2 in FIG. 1A and FIG. 5 is a schematic illustrationof the needles and their relative heights as they are acted upon by the machine cams.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As used in the present specification the term assembly of discrete fibers is intended to define a continuous cohesive length of fibers having a cross-sectional dimension that is substantially no greater than the area defined by the hook opening in the needle whereby the that it may be fed through the yarn guide tube to the needles. On the other hand, the frictional forces between the fibers and the twist or the roving or assembly should not be such that the rotating brushes hereafter described cannot convert the assembly into individual fibers. Adhesion may also be controlled by using appropriate fiber finishes that are applied to the fibers before the roving is formed. Thus finishes may be used which provide good adhesion between the fibers with the adhesive material degradable by application of heat or moisture. In such arrangements the application of heat may result in a decrease in viscosity of the finish so the fiber to fiber adhesion decreases. Alternatively, the heat sublimes or evaporates the finish or in a mixture together to form a continuous strand suitable for weaving or knitting.

Referring now to the drawings there is illustrated an assembly of discrete fibers arranged in a continuous cohesive elongated assembly of fibers as illustrated at 1 in FIG. 2. This assembly of fibers may take the form as indicated above of a loosely spun yarn or roving. This roving or looselyspun yarn is fed directly to thehooks 8 of the needles 2 (FIG. 3) of the circular knitting machine. The assembly I is initially fed through the yarn feed tube 4 (FIG. 2) of conventional design. The yarn feed tube should be provided with a means for flowing air at constant rate down its length toward the needles of the machine thus assuring uniform delivery of the assembly of fibers to the needles so that a relatively weak assembly of fibers will be transported through the yarn guide tube continuously. If the roving breaks in the yarn guide tube the air flow still provides the needles with a continuous supply of the assembly of fibers.

The assembly of fibers is initially engaged by the needles at 6 (FIG. 2) in such a manner as to totally enclose the assembly of fibers within the opening 7 defined by the hook 8 of the needle 2 as illustrated in FIG. 3. The

assembly of fibers is caught by the needles in one embodiment of the invention at a vertical height indicated by line 9 in FIG. 5 and as the needle cylinder continues to rotate the needles 'move downwardly to level 10. At this level 10 the assembly of fibers are acted upon by a brushing means 12. This brushing means separates the assembly-of'fibers into individual tufts with each tuft engaged by the hook of a needle as hereafter described in greater detail. After the needles pass the segment of rotation of the needle cylinder in which they are subject to brushing, a backing yarn 13 is picked up and the needles are dropped through levels 11 for subsequent knitting operations in which that yarn is knit into a backing and the tufts are secured to the stitches as a pile. In this process appropriate camming mechanisms for the knitting machine are used to provide that the assembly of fibers is picked up by the needles at level 9, that the needles are held at an appropriate level 10 for bushing by the brush means 12, and at appropriate levels for feeding the backing yarn to the needles and for subsequent conventional knitting.

Referring now to the brush means, the brush may typically comprise a metal cylinder having a diameter of between 4 and 7 inches and a width of approximately 2 V2 to 4 inches. This width is defined by the distance between the two circularfaces of the cylindrical drum. The width of the cylinder 15 is covered with a series of bristles or wires 16,17 and 18. In a preferred embodiment of the invention the brush varies in stiffness. The

of finishes the heat evaporates or sublimes or attacks components of the finish leaving behind the material which provides good fiber to fiber lubrication.

The assembly of yarn does not include what is normally deemed to be a sliver of fibers. A sliver is generally defined as a continuous strand of loosely assembled fibers that is uniform in cross-sectional area without twist. Such fibers are produced by cards, drawing and gill frames, combers, or the like and is defined and distinguished from the assembly of fibers defined herein by its cross-sectional area which ordinarily would not be normally engageable in its entirety by the hook of needles of the circular knitting machine. Yarns are also distinguished from the assembly of fibers herein defined since yams are deemed to include fibers twisted portionof the brush closest to the yarn guide 4 is the softest and at the opposite end of the brush and bristles or wires arethe stiffest. This arrangement permits the softest portion of the brush to first rough up the surface of the roving so that some fibers protrude between the needles. This is intended to prevent roving from sliding along between the hooks. Once the roving is so stabilized in the hooks or the needles stiffer brush sections begin to disrupt the yarn so that by the time the roving is no longer in contact with the brush only fibers exist on the hooks or the needles and the roving no longer exists. This is illustrated by the sequence of disruptions of the assembly of fibers illustrated at 20, 21, 22 and 23. At point 20 the fibers have been bent so that they project into a position in which they will not easily be dislocated from the needles. At point 21 there is considerable separating but still the assembly retains a somewhat continuous form. At point 22 the assembly is essentially disrupted with only a few fibers remaining that span the distance between adjacent needles. These needles incidently may vary in distance apart depending upon the specific machine involved. But typically the needles may be spaced apart one-tenthof an inch. At point 23 the fibers are totally separated into individual'tufts as illustrated at 24.

The brush cylindrical drum 15 may comprise a series of stepped portions or portions having different diameters in order to attain a brush having varying portions of stiffness. Thus for example the bristles or wires 16 are longer than bristles or wires 17 and bristles or wires 17 in turn are longer than those bristles or wires 18. These wires are secured respectively in-stepped portions of the cylinder to attain a brush having wire tips that are essentially coplanar but with wires of different lengths.

The tips of the wires should preferably project between but not substantially beyond a plane defined by the needles. The number of bristles or wires may vary depending upon the specific effects desired. Preferably the density should be such that at least one wire or bristle normally is projected between an adjacent needle at a given time. The drum 15 may however be covered with wires or bristles with densities in theorder of 200 to 600 wires or bristles per square inch. The wire should also have sufficient fiexibility'to permit movement of the needles in their normal rotary motion past the wire without breaking or bending the needles in the event of contact between the needle and'the wire or bristle. Such contact is normal since the bristles or wires move at a much faster linear speed than the needles.

Individual fibers may span the distance between two or more needles. Ordinarily the length of the fibers of the assembly will be in the order of magnitude of /2 inch or more. The brushing action of the wires which must be upwardly as viewed in FIG. 2 or counterclockwise as viewed in FIG. 1A and as illustrated by the arrow 25 thus engages the individual fibers and pulls them from engagement with all but one of the needle hooks, thus permitting the free ends of these individual fibers to be brushed upwardly against the hook of the needle into an essentially U-shaped configuration. By the contained action of the successive wires or bristles 16, 17 and 18 the tufts illustrated at 24 are formed just as the needles are reaching the stage at which the backing yarn is inserted into the needles.

In practicing the invention the weight of the pile is directly related to the weight of the roving fed to the needles. This weight however has an upper limit depending upon the capacity of the hooks of the needles. That is, the roving cannot exceed the opening in the hook of the needle. Quantitatively in a machine which contains 10 needles per inch, the total weight of fiber on any one needle cannot exceed the weight of onetenth of an inch of roving unless the roving is fed to the hooks of the needles at a linear speed greater than the linear speed of the cylinder of the machine or unless an apparatus as illustrated in FIG. 4 is utilized. This device effectively acts upon the roving to draw a greater amount of fiber material from the source of the fiber just before the fiber is treated to fonn the individual tufts.

FIG. 4 illustrates an ancillary device positioned in front of and operating independently of the brush l2.

The device of FIG. 4 provides a means for forming loops of the assembly between adjacent needles. The device of FIG. 4 may take the form of a slotted wheel synchronized in rotation with the movement of the needles, as illustrated, or sinkers which are in a sinker cylinder. The slotted wheel 27 is supported on a rotatable shaft 30 and has a series of notches 31 in its outer periphery, which resemble a gear. The shaft 30 is suitably driven and geared to the needle cylinder drive source so that the shaft 30 rotates at a speed synchronized with the movement of the needles so that the needles can pass through the notches 31 while the projecting por tions of the wheel engage the portions of the assembly between'adjacent needles 26 and push these portions axially inwardly to form a loop 29 between adjacent needles. The sinker works in a similar fashion.

Calculations may be made to illustrate-the scope and application of the invention and in addition to provide means for determining the parameters of the required fibers for a given end product. A pile fabric when removed from the knitting machine and not backcoated, sheared or otherwise finished consists of two elements: (1) the pile, and (2) the backing yarn. The

When the pile in the form of an assembly of discrete fibers is inserted into the knit structure, the length of this assembly of discrete fibers in one course is equal to the circumference of the needle ring of the knitting machine, which for a knitting machine of 23 inches diameter is 72.3 inches. Thus, the weight per yard of this assembly of discrete fibers (W) is Usually in textile practice, yarn sizes are given in units of length/weight, or the reciprocal of the equation shown above. Thus, the yam size (S) of W would be Typically sliver knit fabrics, as removed from the knitting machine (and not finished or backcoated): weigh in the range of 20-60 oz. per linear yard; are about 48 .inches wide; backing yarn for each yard is usually in the range of 5-10 02.; and have about 20-27 courses per inch.

Taking a typical fabric weighing 30 oz. per linear yard with the backing yarn 6 oz., and using 25 cpi (these values in units of lbs. and yards) I 723x35 v i 1200 yards/lb.

In order to determine the diameter of this assembly of discrete fibers we may use the equations given in an article by Van Issum and Chamberlain (J. Text. Inst. 50 PT599-T623, 1959) D (mils) 42.4/ Vi? 3.4 0.261)

where K is yarn size given in units of Cotton Count (the number of 840 yard hanks per pound) and T is twist of the asembly of discrete fibers.

In the example given above 1,200 yards/lb.- is equivalent to 14.88 in Cotton Count and the twist can be low (about 3 twists/inch) as would be expected in this invention. Therefore,

D (mils) 42.4/ V 14.88 (3.4 0.26 X 3) 42.4/3L86 (2.62) 10.97 2.62 13.59 mils Typically the opening in the hook of the needle on a having means for feeding a base yarn to knitting instrumentalities, and means to cause said intrumentalities to knit stitches of yarn to form fabric, said instrumentalities including an annular row of upwardly extending knitting needles and means for rotating said needles about a common axis, comprising means for continuously feeding to said needles at a first position a plurality of discrete fibers arranged in a continuous cohesive elongated assembly, a cylindrical brush having a plurality of bristles radiating from the axis of said brush, said bristles defining different degrees of stiffness axially along said brush whereby the continuity of said assembly may be gradually disrupted, means axially supporting said brush with the axis thereof normal to the axis of said row of needles and with a portion of said bristles projecting between adjacent ones of said needles along a segment of said row. I 2. Apparatus as set forth in claim 1 wherein said cylinder is arranged with successive axial bands of bristles of different 'stiffnesses-

Claims (2)

1. Apparatus for use in a circular knitting machine having means for feeding a base yarn to knitting instrumentalities, and means to cause said intrumentalities to knit stitches of yarn to form fabric, said instrumentalities including an annular row of upwardly extending knitting needles and means for rotating said needles about a common axis, comprising means for continuously feeding to said needles at a first position a plurality of discrete fibers arranged in a continuous cohesive elongated assembly, a cylindrical brush having a plurality of bristles radiating from the axis of said brush, said bristles defining different degrees of stiffness axially along said brush whereby the continuity of said assembly may be gradually disrupted, means axially supporting said brush with the axis thereof normal to the axis of said row of needles and with a portion of said bristles projecting between adjacent ones of said needles along a segment of said row.

2. Apparatus as set forth in claim 1 wherein said cylinder is arranged with successive axial bands of bristles of different stiffnesses.

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