US3054280A

US3054280A - Fabric tensioning means for circular knitting machine

Info

Publication number: US3054280A
Application number: US825922A
Authority: US
Inventors: Herman E Crawford
Original assignee: H E CRAWFORD CO Inc
Current assignee: H E CRAWFORD CO Inc
Priority date: 1959-07-09
Filing date: 1959-07-09
Publication date: 1962-09-18
Anticipated expiration: 1979-09-18

Description

p 1962 H. E. CRAWFORD 3,054,280

FABRIC TENSIONING MEANS FOR CIRCULAR KNITTING MACHINE Filed July 9, 1959 I N V EN TOR. Herman 6/010/6/0 A TTOR/VEY United States Patent Ofilice 3,054,280 Patented Sept. 18, 1962 FABRIC TENSIONING MEANS FOR CIRCULAR KNITTING MACHINE Herman E. Crawford, Kernersville, N.C., assiguor to H. E. Crawford Company, Incorporated, Kernersville, N.C., a corporation of North Carolina Filed July 9, 1959, Ser. No. 825,922 3 Claims. (Cl. 66-449) This invention relates to circular knitting machines for knitting ladies sheer stocking fabrics and more particularly to means in such machines for applying a uniform tension to the fabric during formation of the stitches thereof.

In circular knitting machines and particularly such machines for knitting stocking fabrics, the fabric as it is knitted is carried downwardly away from the needles under tension through the interior of the needle cylinder and the completed fabric is dropped or ejected from the bottom of the cylinder. In one form of fabric tensioning means the fabric is entrained by an air stream which is directed downwardly through a tube stationarily positioned within the needle cylinder. During rotary operation of the needle cylinder, the fabric which rotates with the cylinder, is drawn by the flow of air against and tends to cling to the inner surface of the tube with the result that an uneven tension is applied to the fabric by the air stream. Heretofore, in order to overcome the tendency of the fabric to cling to the surface of the tube bridge members were provided at spaced points around the inner surface of the tube to deflect portions of the fabric away from the tube and permit the air flow to engage both inner and outer surfaces of the fabric. However, while portions of the fabric were freed from the inner surface of the tube by the bridge members, the flow of air continued to press the fabric against portions of the tube intermediate the bridge members and particularly at points adjacent the stitch drawing cams which resulted in the drawing of uneven fabric stitches.

It is therefore an object of the invention to provide means in a circular knitting machine for overcoming the above mentioned and other difliculties encountered in the use of an air flow for entraining and tensioning stocking fabric knitted on such machines.

Another object of the invention is to provide means in a multifeed circular knitting machine having a tube through which the fabric is entrained by a current of air, which means acts to deflect the fabric away from the surface of the tube at a point adjacent to the point at which the needles reach their lowest stitch drawing position at each of the feeds whereby the air flow exerts a uniform pull on the fabric stitches as they are formed.

With these and other objects in view which will become apparent from the following detailed description of the illustrative embodiment of the invention shown in the accompanying drawings, the invention resides in the novel elements, features of construction and cooperation of parts, as hereinafter more particularly pointed out in the claims.

In the drawings:

FIGURE 1 is a cross-sectional view taken through a portion of the needle cylinder of a multifeed circular knitting machine and diagrammatically showing air operated take-up means for tensioning the fabric and fabric deflecting means according to the invention associated with the take-up means;

FIG. 2 is a plan View on an enlarged scale of the needle cylinder shown in FIG. 1;

FIG. 3 is a cross-sectional view on an enlarged scale taken along the line 3-3 of FIG. 2; and

FIG. 4 is a View diagrammatically illustrating the fabric deflecting means in relation to the forward stitch drawing cam at each of the feeds of the machine.

Referring to the drawing there is shown a portion of a circular knitting machine, of the type shown and described in my Patent No. 2,861,440, issued November 25, 1958, for knitting tubular stocking fabrics, including a needle cylinder 10 having slots 11 for slidably mounting latch needles 12 and jacks 15 (FIG. 1). Associated with the needles 12 is a sinker mechanism 16 including sinkers 17 which are mounted in slots for radial sliding movement and are operated by cam means (not shown) in cooperation with the needles during stitch forming movements thereof. The machine is adapted for twofeed knitting during both rotary and reciprocatory operation and is provided with main and auxiliary knitting stations indicated generally at 20 and 21, respectively; At each of the knitting stations the needles are operated through knitting and stitch drawing movements by cams diagrammatically indicated at 22 and 25 (FIG. 2) earns 25 acting on the needles during rotary and forward or counterclockwise reciprocatory movements of the cylinder 10 and cams 22 acting on the needles during reverse reciprocatory movements of the cylinder. Each of the feeds is also provided with fingers 26 for feeding yarns to the needles.

In order to apply tension to and to draw the fabric downwardly away from the needles as it is knitted the fabric is guided into a funnel-shaped end 27 of a tube 30,

the enlarged opening of the end 27 preferably terminating adjacent to the upper end of the needle cylinder 10. The tube 30 is mounted in stationary position in and extends downwardly through the interior of the needle cylinder as shown in FIG. 1. The end of the tube 330 remote from the needle cylinder 10 is connected to and in communication with the interior of a collecting chamber or receptacle 31 which is adapted to receive the completed stocking fabrics. The receptacle is connected by a second tube 32 to the intake side of a suction type fan 35 which is driven by a motor 36. The fan 35 is operated to create a flow of air downwardly through the tube 30 to tension the stocking fabric as it is formed on the needles 12 and to entrain and carry the completed fabric to the collecting receptacle. The receptacle 31 is provided with an opening (not shown) through which the completed fabrics may be removed from the receptacle and a door 37 for normally closing the opening.

During knitting of the rotary or run-down portions of the fabric the downward movement of the air through the tube 30 causes the fabric to be pressed tightly against the inner surface of the funnel-like end 27 of the tube and the resulting friction developed between the fabric and tube tends to resist the free movement of the fabric thereby causing improper drawing of the fabric stitches. Heretofore, arch-shaped members were provided at spaced positions around the inner surface of the funnellike end 27 which acted to lift the fabric from theinner surface to permit the air flow to engage both sides of the fabric and to assist the movement of the fabric downwardly through the tube. However, while such archshaped members did act to deflect the fabric away from spaced portions of the inner surface of the portion 27, the fabric continued to engage the inner surface of the end 27 particularly adjacent to the point at which the needles reached their lowest stitch drawing position thus preventing the drawing of stitches of uniform length.

In accordance with the instant invention, the fabric is deflected away from the inner surface of the end 27 of the tube 30 so that the stream of air not only engages and tensions both inner and outer surfaces of the fabric but also acts directly on the fabric at the point at which each needle reaches its lowest (stitch drawing) position in drawing a new stitch. The means for this purpose is provided at each of the

feeds

20 and 21 and comprises an elongated wire bridge member 40 of metal or other suitable material which is secured to the inner surface of the end 27 of the tube 30 adjacent to the cam 25 for operating the needles during forward movement of the cylinder 10. As shown in FIGS. 1 and 2, one end of the bridge member 40 lies adjacent to the upper edge of the end 27 and the member extends downwardly and at an angle to the vertical center of the tube and in the direction of the forward movement of the cylinder 10. From its upper end the member 40 inclines inwardly from the inner surface of the end 27 as viewed in FIGS. 2 and 3 to a leading end 41 of a high portion 42 and from the latter the member inclines outwardly to its lower point of engagernent with the end 27. As shown in FIG. 2, each member 40 is positioned in the end 27 with the leading end 41 of the high portion 42 substantially coincident with a radial line, indicated at 45, extending between the center of the cylinder and a low stitch drawing face of the cam 25 (FIG. 4).

The relation of the member 40 with respect to the cam 25 at each of the feeds and 21 is such that as the cylinder 10 and fabric is rotated in the forward direction the needles engage the cam 25 to start their downward stitch drawing movement and the fabric engages and rides up the leading inclined surface of the member 40. As the heads of the needles pass through the previously formed stitches, the fabric reaches the leading end 41 of the high portion 42 of the member 40 and the stream of air exerts a direct pull on the previously formed stitches to thereby maintain a constant tension on the fabric at the point each new stitch is formed. Further, as the needle cylinder 10 continues its movement in the forward direction, the fabric rides along the high portion 42 of the member 40 to maintain tension on the new fabric stitches as the needles rise therethrough for the stitch drawing movement at the next feed of the machine.

It will be understood that the improvements specifically shown and described by which the above described results are obtained can be changed and modified in various ways without departing from the invention herein disclosed and hereinafter claimed.

I claim:

1. In a multifeed circular knitting machine having a needle cylinder adapted for rotary movement in a forward direction, needles in said cylinder, means for feeding yarn at each of said feeds, a cam at each of said feeds for operating said needles through stitch drawing movements during rotation of said cylinder in said forward direction to form a tubular stocking fabric, a stationary tube within said cylinder, and means for creating a flow of air in said tube to apply tension to and to entrain said fabric downwardly through said tube, in combination with means at each of said feeds for deflecting the fabric away from the inner surface of said tube to change the angular path of said fabric in relation to said tube during said fabric entraining movement, said last mentioned means being operative during said forward rotation of said cylinder and comprising a member secured to the inner surface of said tube over which said fabric is drawn by said flow of air, said member having a high portion positioned on a radial line extending from the center of said cylinder through said needles at a point substantially coincident with the lowest stitch drawing position of said needles.

2. In a multifeed circular knitting machine having a needle cylinder adapted for rotary movement in a forward direction, needles in said cylinder, means for feeding yarn to said needles at each of said feeds, a cam at each of said feeds for operating said needles through stitch drawing movements during rotation of said cylinder in a forward direction to form tubular stocking fabric, a stationary tube within said cylinder, and means for creating a flow of air through said tube to apply tension to and to entrain said fabric downwardly through said tube, in combination with means at each of said feeds for deflecting the fabric away from the inner surface of said tube to change the angular path of said fabric in relation to the inner surface of said tube during said fabric entraining movement, said last mentioned means being operative during forward rotation of said cylinder and comprising a member secured to the inner surface of said tube over which said fabric is drawn during said entraining movement, said member having a high portion the leading edge of which is positioned on a radial line extending from the center of said cylinder through said needles at a point substantially coincident with the lowest stitch drawing position of said needles.

3. In a multifeed circular knitting machine having a needle cylinder adapted for rotary movement in a forward direction, needles in said cylinder, means for feeding yarn to said needles at each of said feeds, a cam at each of said feeds for operating said needles through stitch drawing movement during rotation of said cylinder in said forward direction to form tubular stocking fabric, a stationary tube within said cylinder, and means for creating a How of air to apply tension to and to entrain said fabric downwardly through said tube, in combination with means at each of said feeds for deflecting the fabric away from the inner surface of said tube to change the angular path of movement of the fabric in relation to the inner surface of said tube during said fabric entraining movement, said last mentioned means being operative during forward ro tation of said cylinder and comprising a member secured to the inner surface of said tube over which said fabric is drawn during said entraining movement, said member having a high portion the leading edge of which is positioned on a radial line extending from the center of said cylinder through said needles at a point substantially coincident with the lowest stitch drawing position of said needles, and an inclined portion for camming said fabric from said inner surface of said tube to the leading edge of said high portion of said member.

References Cited in the file of this patent UNITED STATES PATENTS 2,641,117 Desmonds June 3, 1953 2,844,952 Wawzonek June 29, 1958 FOREIGN PATENTS 202,394 Australia July 5, 1956 1,183,041 France Jan. 26, 1959