Double-knit circular knitting machine

Abstract: A method of knitting a thickened double-­ knit fabric and a circular knitting machine for this use is disclosed. Sinkers (15) are supported for inward and outward movement between cylinder needles (2) and dial needles (3). Each sinker (15) includes a stitch drawing ledge (15a) and a neb (15d) on the inner end portion of each of the sinkers and cooperates with adjacent needles (2,3) in the formation of knit stitch loops. The outer end portions of the sinkers are supported on a rotatable ring (14) located exteriorly of the needle cylinder (1) for movement of the sinkers (15) in a radial direction and along a downwardly inclined path of travel between the needles (2,3). The inner end portions of the sinkers (15) are supported for movement along the downwardly inclined path of travel. When the cylinder needles (2) and dial needles (3) are in a clearing position, yarn is fed thereto. While the cylinder and dial needles (2,3) are successively moved downwardly and inwardly, the sinkers (15) are simultaneously moved in an outwardly and upwardly direction along the downwardly inclined path of travel. While the cylinder and dial needles (2,3) are respectively lowered and retracted, the stitch drawing ledge (15a) engages the yarn and cooperates with associated adjacent needles (2,3) to form stitch loops of a length determined by the amount of upward vertical movement imparted to the stitch forming ledge (15a) of the sinker and the amount of downward and inward movement of the cylinder and dial needles (2,3).

Description: This invention relates generally to a double-knit circular knitting machine wherein the vertical length of travel of the cylinder needles is reduced by lowering the stitch forming ledge of the sinkers as the needles are being raised to clearing level and raising the stitch forming ledge of the sinkers as the needles are being drawn downwardly to stitch drawing level, and more particularly, to such a machine wherein the sinkers are supported for inward and outward movement between the dial and cylinder needles along a downwardly inclined path of travel and with the sinkers being moved outwardly and upwardly as the needles are drawn downwardly to raise the level of the stitch drawing ledge during stitch loop formation and with the sinkers being moved inwardly and downwardly as the needles are raised so that the shed stitch loops are moved inwardly and downwardly by the nebs of the sinkers. During movement of the cylinder and dial needles in a conventional double-knit circular knitting machine, a newly formed loop slides downward on the needle stem and provides the various pattern structures desired. When forming a pattern structured fabric, such as a rib knit structure, any yarn breakage during knitting typically results in the knit fabric dropping from the machine. When dropping occurs, the yarn from the cup end of the dropped fabric must be threaded onto at least every two or three needles and then restored to its initial state before dropping. This mandates an operator's slowly running the knitting machine to assure proper threading. In JP-A 63-42186, a double-knit circular knitting machine is disclosed which solves some of the aforementioned problems by the application and use of a novel sinker. However, as disclosed in this Japanese publication, the distance between the foremost end of the sinker and the rotating dial is shortened when the sinker advances to the inside of the machine. As a result, a thick fabric cannot be knitted unless the dial is upwardly moved for increasing the separation distance so as to allow a knitted fabric to easily pass through the formed gap without interference. Because the sinker is arranged perpendicularly to the knitting needle, the sidewall of the sinker rest ring is small, thus creating an unstable sinker movement. With a view to reducing the stroke of the cylinder needles of a single knit circular knitting machine, US-A-4180993 describes a sinker configuration in which each sinker has a downwardly inclined edge adjacent the inner or needle cylinder end of the sinker cooperating with a surface at the cylinder end of the sinker groove or slot so that, as the sinker is retracted outwardly and advanced inwardly by its sinker cam, the cylinder end of the sinker is rocked upwardly and downwardly. The cylinder end of each sinker is raised as adjacent needles move downwardly and vice versa . Similarly to the aforementioned US specification, in US-A-925036, the sinkers of a rib circular knitting machine having cylinder and dial needles are rocked upwardly and downwardly as the sinkers are reciprocated radially so as to provide for "knocking over" of the stitches on the dial needles, thus dispensing with the need to use weights, draft rolls or like devices for imparting tension to the knitted fabric. It is an object of the present invention to provide a double-knit circular knitting machine which overcomes the aforementioned deficiencies of the prior art. The present invention consists in a double-knit circular knitting machine including a plurality of cylinder needles supported in a rotating needle cylinder for vertical movement parallel to the axis of rotation of said needle cylinder, a plurality of dial needles radially slidable on a dial and operative with said cylinder needles, knitting cam means for raising said cylinder needles to a clearing level and for advancing said dial needles outwardly and then lowering said cylinder needles and retracting said dial needles inwardly, sinkers supported for inward and outward movement between said needles, each of said sinkers including a stitch drawing ledge and a neb on the inner end portion of each of said sinkers and cooperating with adjacent needles in the formation of stitch loops, and means supporting said sinkers for movement in a radial direction between said needles and including radially extending sinker slots slidably supporting outer end portions of said sinkers, characterised in that said sinker supporting means supports said sinkers also for movement along a downwardly inclined path of travel and comprises rotatable ring means of inverted truncated conical shape located exteriorly of said needle cylinder and having said radially extending sinker slots formed therein, and a rotatable sinker nose support ring positioned on the upper end of said needle cylinder for slidably supporting inner end portions of said sinkers, said sinkers being inclined downwardly and inwardly toward said needles. With the invention, yarn is fed to the needles when the cylinder needles are in a raised, clearing position and when the dial needles are in an outward advanced position. The cylinder needles are successively moved downwardly while the dial needles are successively moved inwardly. The sinkers are simultaneously moved in an outward and upward direction along the downwardly inclined path of travel while the cylinder needles are being lowered and the dial needles are being retracted so that the stitch drawing ledge engages the yarn. The stitch drawing ledge cooperates with the associated adjacent needles to form stitch loops of a length determined by the amount of upward vertical movement imparted to the stitch forming ledge and the amount of downward and inward movement of the cylinder and dial needles. The cylinder needles are successively moved upwardly and the dial needles are successively moved outwardly after forming the stitch loops therewith. The sinkers are simultaneously moved in an inwardly and downwardly direction along the downwardly inclined path of travel to engage the sinker nebs with the fabric and move the same inwardly and downwardly to aid in shedding the stitch loops from the cylinder and dial needles as they are respectively raised and advanced with the newly formed stitch loop thereon. In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which:- Figure 1 is a vertical sectional view through the needle cylinder of the knitting machine and illustrating the manner in which the sinkers are mounted for radial sliding movement along a downwardly inclined path of travel relative to the needles; Figure 2 is a side elevational view of one of the special type of sinkers utilized in the present invention; Figure 3 is a somewhat schematic developed elevational view showing the paths of travel of the needles and associated sinkers at one yarn feeding position; Figures 4 through 10 are side elevations of the upper portions of the cylinder and dial needles and associated sinkers showing their relationship during the successive steps of forming stitch loops and then shedding the previously formed stitch loops from the dial and cylinder needles, and being taken along their respective section lines 4-4 through 10-10 of Figure 3; and Figure 11 is a side elevational view of a second embodiment of the special type of sinker used in the present invention. As shown in Figure 1, a rotating needle cylinder 1 is supported on a driven ring gear 6 and the outside surface of the needle cylinder 1 is provided with the usual needle slots 1a in which cylinder needles, broadly indicated at 2 , are supported for vertical movement parallel to the axis of rotation of the needle cylinder 1 . As illustrated, hooked latch needles are preferred. Each knitting needle 2 is provided with a hook 2a and a pivoted latch 2b (Figure 4), and an operating butt, as indicated at 2c (Figure 1). Conventional knitting cams, including stitch cam means supported on cam plates 9 , are provided for imparting vertical movement to the knitting needles 2 . The cam plates 9 are supported on the inner surface of the cam holder ring 8 which is fixed on a cam ring plate 10 . A rotating dial 4 is supported on a needle dial hub 7 . The outer surface of the dial 4 is spaced from and extends over an upper portion 1b of the rotating needle cylinder and is rotatable therewith. The top surface of the dial 4 is provided with the usual needle slots in which hooked latch dial needles, broadly indicated at 3 , are supported for radial movement in conjunction with cylinder needles 2 during knitting operation. Each dial needle 3 is provided with a needle hook 3a and latch 3b (Figure 4), and an operating butt 3c (Figure 1). Knitting cams, including stitch cam means supported on dial cam plate 12 , are provided for imparting radial, horizontal movement to the knitting needles 3 . The dial cam plate 12 is supported on the lower surface of a dial cam holder ring 11 which is fixed to a dial cam ring plate 13 . The upper surface of the needle cylinder includes the downwardly and inwardly inclined surface 1b which defines a sinker nose support ring for the nose of the sinkers as will be described herein. A sinker support bed 14 is fixed to the exterior of the upper end of the needle cylinder 1 and is provided with a downwardly and inwardly inclined sinker sliding surface 14a defined by the lower ends of sinker slots formed in the sinker bed 14 and at the same downwardly inclined angle as the sinker sliding surface 1b of the sinker nose ring defined on the upper surface of the needle cylinder 1 . The inclined surface 1b and the sliding surface 14a collectively define sinker support ring means of inverted truncated conical shape. As illustrated, the sinker sliding surface 14a is located at a lower level than the sinker sliding surface 1b . Special types of sinkers, broadly indicated at 15 , cooperate with the cylinder and dial needles 2 , 3 to form stitch loops and are supported for movement in a radial direction and along a downwardly and inwardly inclined path of travel between the cylinder needles 2 . Inward and outward radial sliding movement of the sinkers 15 , along the downwardly and inwardly inclined path of travel, is controlled by sinker cams 17 supported in a fixed position on a sinker cap 16 . Sinker cap 16 is in turn supported on a sinker cap ring 18 which is supported in spaced-apart locations on the upper ends of support standards 19 surrounding the needle cylinder 1 . As will be noted, the sinker cams 17 are supported in a downwardly inclined position at the same downwardly inclined angle as the inclined sliding surfaces 1b and 14a on the respective inclined cylinder surface and sinker bed 14 . The sinker sliding surfaces 1b and 14a are illustrated in Figure 1 as being downwardly and inwardly inclined at an angle of around 20° relative to a line perpendicular to the vertically disposed cylinder needles 2 . While this 20° downwardly inclined angle is preferred, the present invention is not limited to this particular angular inclination, but may be positioned at an angle from 10° to 45°, and preferably within the range of 15° to 30°. As best shown in Figure 2, the outer portion of the special sinker 15 includes an elongate body portion having an outer lower planar sliding edge 15e adapted to rest upon and slide along the inclined surface 14a of the sinker bed 14 . The sinker 15 also includes an inner lower planar sliding edge 15b adapted to rest on and be slidably supported along the inclined sliding surface 1b on the upper surface of the cylinder 1 . The inner sliding edge 15b is disposed at a higher level than the outer sliding edge 15e , as clearly shown in Figure 2. A stitch drawing ledge 15a is provided on the upper inner portion of the sinker and a neb 15d extends over the outer portion of the stitch drawing ledge 15a and defines a sinker throat 15c between the neb 15d and the outer portion of the stitch drawing ledge 15a . An upstanding operating butt 15f is provided on the outer and upper end portion of the elongated body portion of the sinker 15 . The butt 15f extends upwardly at a right angle from the body portion of the sinker 15 and is adapted to be engaged by the sinker cams 17 to impart the required inward and outward radial movement to the sinkers 15 . In conventional sinkers, the stitch drawing ledge extends along a line which is parallel with the lower planar sliding edge of the sinker. In contrast to this conventional construction, the present special type sinker is characterized by the stitch drawing ledge 15a being slanted downwardly toward the operating butt 15f on the outer end portion of the elongate body portion of sinker 15 . The downwardly inclined or outwardly slanting stitch drawing ledge 15a of the sinker 15 of the present invention is different from the normal type sinker in which the stitch drawing ledge extends parallel to the lower planar sliding edge of the sinker. The present sinker is also different from the special sinkers of the type disclosed in U S-A 3,837,185 and 3,986,371 wherein the stitch drawing ledge slants downwardly or inwardly in the direction of the inner end of the sinker. In Figure 3, the solid line 50 indicates the path of travel of the top of the hook of the cylinder needles 2 during a knitting cycle while the dash-dot line 52 indicates the radial path of travel of the stitch drawing ledge 15a during a knitting cycle. The dotted line 51 indicates the path of travel of the dial needle 3 . The alternate long and double-dashed line 53 indicates the path of travel of the sinker throat 15c . A yarn feed carrier and finger 20 (Figures 1 and 8) is positioned to feed a yarn indicated at 54 (Figure 8) to the needles as they are moved to a stitch forming level. In the method according to the invention, the needles 2,3 are successively raised as they approach the knitting station and are moved outwardly to the clearing level along the solid line 50 in Figure 3 to a position where the previously formed loops surrounding the shanks of the cylinder and dial needles 2,3 are positioned beyond the tip of the latches 2b, 3b , as shown in Figures 4-6. At the same time, the sinkers 15 are moved and retained in an inwardly and downwardly inclined position along the downwardly inclined path of travel between the needles 2,3 so that the fabric is moved inwardly by the neb 15d to maintain the previously formed stitch loops below the tip of the latches 2b, 3b and in tight engagement with the shanks of the needles, as shown in Figure 6. The inward and downward movement of the sinker 15 lowers the position of the stitch drawing ledge 15a below the normal horizontal path of travel, as indicated by the dash-dot line 52 in Figure 3, so that the cylinder needles 2 do not have to be raised as high to reach clearing level as would be the case if the sinkers 15 were maintained at a higher level. While the cylinder needles 2 are in a raised latch clearing position, and the dial needles 3 are in a most outwardly advanced position, yarn feed finger 20 feeds the yarn 54 to the hooks of the needles 2, 3 . The cylinder needles 2 are lowered and dial needles 3 are retracted while the sinkers 15 begin to move outwardly and upwardly along the downwardly inclined path of travel, as illustrated in Figure 7. With further downward vertical movement of the cylinder needles 2 and further retraction of the dial needles 3 , as indicated in Figure 8, the previously formed stitch loops close the latches 3a, 3b and the sinker 15 continues to move outwardly and upwardly so that the yarn in the cylinder needle hook 2a will be drawn downwardly over the stitch drawing ledge 15a while the stitch drawing ledge 15a remains in the highest level, as illustrated in Figure 9. While the yarn is being drawn down over the stitch drawing ledge 15a , both the outer and inner portions of the sinkers 15 are being supported. As shown in Figures 4-10, the lower planar sliding edge 15b on the inner end or nose of the sinker 15 is slidably supported on the downwardly and inwardly inclined surface 1b of the cylinder 1 . Lower planar sliding edge 15e on the outer end portion of the sinker 15 is slidably supported 14a of the sinker bed 14 (Figure 1). Thus, both the inner and outer portions of the sinkers 15 are supported as the needles are drawn down to stitch forming level. As shown in Figure 10, the cylinder needle 2 begins to rise at the point where the dial needle 3 is retracted to the innermost position. At this time, the sinker moves in the inwardly and downwardly direction so that the previously formed stitch loops shed from the upper end of the needle hook 2a is engaged by the neb 15d and moved inwardly to aid in shedding the stitch loop from the needle. The sinker throat 15c pushes the knit fabric and assists the loop on the dial needle 3 to cast-off the stitch. This inward and downward movement of the sinkers 15 ensures that the needles 2 do not again pass upwardly through the shed stitch loop. The cylinder needle 2 continues to rise and the dial needle 3 begins its advance. This begins the start of the knitting cycle as illustrated in Figure 4. The inward and downward movement of the sinkers 15 ensures that the needles 2 do not again pass upwardly through the shed stitch loop. The sinkers 15 continue to move the fabric inwardly and downwardly as the needle 2 continues to rise, as shown in Figures 4 and 10, so that the newly formed stitch loop is maintained in engagement with the outer surface of the needle shank and imparts an opening motion to the latches of the needles. This knitting cycle is repeated at each of the subsequent knitting stations around the needle cylinder to form the knit fabric. Alternatively, a compound or sliding latch needle with a modified cam also can be used in accordance with the present invention. A jacquard apparatus for patterning which can include a pattern wheel, a pattern drug, or other electronic patterning device also can be included for knitting various artistic patterns. The shape of the sinker is not limited. For example, Figure 11 illustrates a second embodiment of the special type of sinker used in accordance with the present invention. The sinker grooves or slots in the machine can be modified as needed. The forward end of the sinker 150 includes a stitch drawing ledge 150a extending horizontally. Inclined surface 150b is in a plane defined by the inclined surface 150e so that the entire lower edge of the sinker defined by both surfaces 150b, 150e are guided by sinker grooves. Sinker 150 includes a throat 150c and a neb 150d . A control butt 150f is included. The use of sinkers 15 in accordance with the present invention offers several benefits. If a knit fabric drops on account of yarn breakage during knitting, the machine can be threaded in a similar manner as a single-knit circular knitting machine. Additionally, a thick fabric can be knitted. The inwardly and downwardly inclined direction of the sinker provides a gap between the tip of the sinker knitting ledge 15a and the needles 2,3 . Therefore, a knitted fabric can pass between the gap. Thus, the winding tension is more readily applied to the knit fabric which results in the potential for higher quality and a larger knit fabric thickness.

Claims: A circular knitting machine including a plurality of cylinder needles (2) supported in a rotating needle cylinder (1) for vertical movement parallel to the axis of rotation of said needle cylinder (1), a plurality of dial needles (3) radially slidable on a dial (4) and operative with said cylinder needles (2), knitting cam means (9,12) for raising said cylinder needles (2) to a clearing level and for advancing said dial needles (3) outwardly and then lowering said cylinder needles (2) and retracting said dial needles (3) inwardly, sinkers (15) supported for inward and outward movement between said needles, each of said sinkers including a stitch drawing ledge (15a) and a neb (15d) on the inner end portion of each of said sinkers (15) and cooperating with adjacent needles (2,3) in the formation of stitch loops, and means (14,1b) supporting said sinkers (15) for movement in a radial direction between said needles and including radially extending sinker slots slidably supporting outer end portions of said sinkers, characterised in that said sinker supporting means supports said sinkers (15) also for movement along a downwardly inclined path of travel and comprises rotatable ring means (14) of inverted truncated conical shape located exteriorly of said needle cylinder (1) and having said radially extending sinker slots formed therein, and a rotatable sinker nose support ring (1b) positioned on the upper end of said needle cylinder (1) for slidably supporting inner end portions of said sinkers (15), said sinkers being inclined downwardly and inwardly toward said needles. A circular knitting machine as set forth in claim 1, characterised in that said rotatable ring means is inclined downwardly and inwardly toward said needles at an angle from 10° to 45°. A circular knitting machine as set forth in claim 1 or 2, characterised in that said rotatable ring means supporting the outer end portions of said sinkers is positioned at a lower level than said sinker nose support ring supporting the inner end portions of said sinkers. A circular knitting machine as set forth in claim 1, 2 or 3, characterised in that each of said sinkers has an outer lower planar sliding edge (15e) supported in said sinker supporting means (14), an inner lower planar sliding edge (15b) supported by the sinker nose support ring (1b), and a stitch drawing ledge (15a) and neb (15d) which are positioned horizontally to the downwardly inclined path of travel of the sinkers.

Inventors: KAWASE SHINJI, YORISUE SHOZO, KAWASE, SHINJI, YORISUE, SHOZO
Applicants: PRECISION FUKUHARA WORKS LTD, PRECISION FUKUHARA WORKS, LTD
Application year: 1990
Main classification: D04B15
IPC codes: D04B9, D04B15