Abstract:
A hollow needle tufting apparatus is provided with swivel mounted knives and an improved needle design directed to improve cutting efficiency and the life of the hollow needles and associated knives.

Description:
The present application claims priority to the Jul. 21, 2008 filing date of U.S. provisional patent application Ser. No. 61/082,305. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an improved cutting apparatus utilized in connection with tufting with hollow needles to which a plurality of yarns are selectively fed. 
     BACKGROUND OF THE INVENTION 
     In hollow needle tufting machines, as typified by Kile, U.S. Pat. No. 4,549,496 and Davis et al., U.S. Pat. No. 5,588,383, it is important that the knives be precisely aligned with the angular cutting faces of the hollow needles. In prior art tufting machines with hollow needles spaced on two inch centers, a typical two meter tufting machine might have 75 needles. The alignment between the knives and needles in these machines is generally achieved in two steps. First, the knives and needles are mounted as precisely as possible so that the knife blades will be parallel to the angular surfaces of the hollowed needles. Then the tufting machines are operated and because of pressure placed by the knives against the angular cutting surfaces, the knives and needles wear sufficiently to achieve an acceptable alignment. 
     Historically, the mounting of the hollow needles was itself a time consuming process. Now it has become possible to mount hollow needles more closely to the desired alignment, as in the fashion described in Ingram, U.S. Pat. No. 7,318,383. Therefore, it is desirable to achieve that precise alignment between knife and hollow needle angular cutting surface more easily and without the necessity of operating a tufting machine to achieve the wear-in that has previously provided the final alignment between these parts. In addition, it is desirable to extend the life of the knives and needles and to provide a structure that can be utilized with both fixed knives and knives that are selectively operable to cut only selective yarns. In order to accomplish these and other objectives of the invention, an improved hollow needle is provided with a recess at the rear end of the angular cutting surface. In addition, knives may be mounted to swivel to enable the knives to change their orientation with respect to the hollow needles slightly and thereby achieve the necessarily precise cutting alignment. A knife mount is also provided that may be either locked in a fixed position, or allowed to shift vertically in response to a vertical actuator such as a pneumatic cylinder so that both cut and cut/loop configurations of the tufting machine are possible without the need of a substantial inventory of varying parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The particular features and advantages of the invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings in which: 
         FIG. 1  is an exploded view of an embodiment of a prior art narrow gauge hollow needle tufting assembly. 
         FIG. 2  is a side plan view of a swivel mounted knife assembly of the present invention used for creating cut pile yarn tufts. 
         FIG. 3A  is an enlarged isometric view of an improved hollow tufting needle according to the present invention shown in proximity to the knife edge of an associated knife. 
         FIG. 3B  is a side plan view of the hollow tufting needle of  FIG. 3A . 
         FIG. 4  is a side plan view showing a knife assembly wherein a knife may be selectively operated pneumatically to produce cut and looped tufts of yarn with an alternative sliding embodiment. 
         FIG. 5A  is a sectional plan view of a bushing of the type used in attaching the sliding brackets to the knife block support in  FIG. 4 . 
         FIG. 5B  is a back plan view of the bushing of  FIG. 5A . 
         FIG. 6A  is a back plan view of a sliding bracket of the type shown in  FIG. 4 . 
         FIG. 6B  is a side plan view of the sliding bracket of  FIG. 6A . 
         FIG. 6C  is a front plan view of the sliding bracket of  FIG. 6A . 
         FIG. 6D  is a top plan view of the sliding bracket of  FIG. 6A . 
         FIG. 7  is a sectional view of the knife assembly of  FIG. 4  showing the height adjustment and pneumatic supply. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning first to  FIG. 1 , a cover plate  10  is shown with a yarn feed openings  11  proceeding in a longitudinal row. While the illustrated cover plate has six yarn feed openings, alternative plate designs could easily be created with between about four and eight yarn feed openings  11 . Through a central opening in cover plate  10  is collar  12  which receives an air supply line  13  at its upper end and it connects to tube  14  at its lower end, enabling the tube  14  to guide air downward to its outlet  15 . Cover plate  10  fits over a longitudinal tapered slot  21  in funnel block  20 . It will be appreciated that cover plate  10 , rather than being designed a cover a single slot  21  could be made wider with a plurality of longitudinal rows of yarn feed openings to cover a plurality of slots. In operation, yarns extend downward through openings  11  of the cover plate  10  into a slot  21  of funnel block  20 . Downward directed air pressure through openings  11  and gravity keep the yarns downwardly entrained within slot  21  and the jet of air proceeding from outlet  15  is designed to rapidly encourage a selective yarn downward and into the annular opening  41  of hollow tufting needle  40  positioned beneath a selected tapered slot  21 . The funnel block  20  also has a bottom channel  23  which allows some downwardly directed air flow to escape laterally rather than proceeding through the hollow needles  40 . Funnel block  20  also has lower pin holes  25  for mounting, as with pins  36 , to front needle holder blocks  50 , in addition to central threaded openings  26  and upper pinholes  24  for fastening purposes. At the bottom of slot  21 , cylindrical inserts  22  are inset and the funnel block  20  is mounted over hollow needle heads  42  so that the openings at the bottom tapered slots  21  ending in cylindrical inserts  22  are directly positioned over the openings  41  of hollow needles  40 . The heads of hollow needles  40  have at least one planar side  43 , and in the illustrated embodiments have a pair of parallel opposed planar sides to facilitate alignment. Specifically, rear needle holder blocks  51  and front needle holder blocks  50  are joined by threaded allen bolts  35  in a fashion that leaves a channel  54  extending laterally across their joined upper surface. The channel  54  is defined by opposed planar sides. The opposed planar surfaces  43  of the heads  42  of hollow needles  40  align with the planar sides of the channel  54  to require the hollow needles  40  to be positioned so that the angled cutting surface  44  of needles  40  is precisely aligned in a rearward facing direction. With the two opposed planar surfaces  43  it will be seen that the hollow needles  40  may be aligned with the cutting surface  44  facing either directly forward or directly rearward, however, the rearward direction is selected so that the cutting surface  44  can properly interface with knives  47 , as shown in  FIG. 2 . 
     In operation, backing fabric for tufting is fed over backing support bar  60 . The preferred backing support bars have a series of merlons  62  which are aligned to extend rearward between hollow needles  40  to about the mid point of those needles. Thus, the height of merlons  62  with respect to the interspaced accurate hollows or crenels  61  is about equal to the radius of the hollow needles  40 . The merlons  62  support the backing fabric against the downward pressure applied when angled surfaces  44  penetrate the backing fabric to insert stitches of yarn. 
     The backing support bar  60  has openings  64  and slots  63  for mounting above a knife bar  48 , shown in  FIG. 2 , which holds a plurality of laterally spaced knives  47 . In the illustrated embodiment, knife bar  48  has openings  49  to receive mounting pins  65  which pass through openings  53  in mounting bracket  55 . At the top and bottom of mounting bracket  55  are openings  52  in rearward extending arms that receive swivel pins  58  passing through openings  59  in forward extending arms of swivel brackets  57 . Swivel brackets  57  receive mounting pins  46  passing through openings in clamping blocks  45  and knives  47  thereby securing the knives to the swivel brackets  57 . It can be seem that swivel brackets  57  may pivot or rotate about swivel pins  58  with respect to their associated mounting brackets  55  and the knife bar  48 . In this fashion, the width of each knife edge  39  can be precisely aligned to a position parallel across the angled cutting surface  44  of each hollow needle  40  with relatively little force. 
       FIG. 3A  provides a perspective view of an improved hollow needle  40  according to the invention. Hollow needle  40  is shown with head  42  having a planar surface  43  and an angular opening  41  extending therethrough. At the opposite end of needle  40  is the angular cutting surface  44  beginning at distal end  38  and extending rearward to notch  31 . The slant of the cutting surface generally creates an ovular opening, however, this opening is modified by the creation of notch  31  into which yarn is directed for cutting. Notch  31  has cutting edge  33  which preferably interfaces with knife edge  39  to sever yarn that has been urged down through the angular opening  41  of hollow needle  40  and into notch  31 . A modification on this needle is the placement of hollow  32  just above the notch  31  so that a smaller area of the angled cutting surface  44  is present adjacent to the notch  31  and cutting edge  33 . In this fashion, as the knife edge  39  passes across the angled cutting surface  44 , slightly less wear is imparted to the center of the knife edge  39 . Because the exact operation of the cutting mechanism varies according to operator preference, with some operators beginning contact between the knife edge  39  and angular cutting surface  44  not merely near the midpoint of the cutting surface  44  but very near the forward end of the ovular opening opposite the notch  31 , and some operators continuing the movement of the knife edge  39  not merely until crossing cutting edge  33  but across the entire angled cutting surface  44 , the hollow  32  helps provide more uniform knife edge wear. 
     Additional details of the configuration of the most preferred knife edge  39  and cutting surface  44  and cutting edge  33  of the hollow needle  40  may be described in connection with  FIGS. 3A and 3B . Specifically, the knife edge  39  is not normal to the sides of the knife  47  but instead is sharpened at a slant of approximately 6 degrees. The angled cutting surface  44  is at angle α from the edges of hollow needle  40  and α is preferably about 22 degrees. The cutting edge  33  is formed by the cutting surface  44  and an inward surface formed an angle of approximately 100 degrees, represented by angle γ from the angled cutting surface  44 . The 80 degree supplementary angle is represented by β in  FIG. 3B . 
       FIG. 4  shows an alternative sliding assembly designed for selected operation of knives  47  into contact with cutting surfaces  44  of associated hollow needles  40 . This movement may be imparted pneumatically with mounting brackets  157  that have been loosely received into knife support bar  148 . As in the previously described embodiment, knives  47  are attached to brackets  157  with clamping blocks  45  and mounting pins  46 . However, extending laterally through the front side of sliding brackets  157  are a pair of vertically oriented longitudinal slots  153 . A fastener  170  is placed through a T-shaped bushing  165  and secured in the knife support bar  148  so that the fastener bottoms out in opening  149  of knife support bar  148  before tightly clamping the flange  166  of bushing  165  against the sliding bracket  157 . The slots  153  are also designed with a greater width than the diameter of the stem  167  of bushings  165 . In this fashion, the brackets are moveable vertically in slots  153 . Optionally there may be provided sufficient lateral play to allow the brackets to move about one degree from left to right, thereby permitting precise alignment of knife edge  39  with the angled cutting surface  44 . However, the presently preferred method of obtaining precise alignment is to use the swivel brackets of  FIG. 2 , and the mounting bracket  55  of that design may be modified through the addition of slots to permit the brackets to be slideably mounted and operate to only selectively cut yarns. 
     The sliding brackets  157  of  FIG. 4  are shown in detail in  FIGS. 6A through 6D  and the bushings  165  are shown in  FIGS. 5A and 5B . These sliding brackets  157  and bushings  165  may be used in a cut pile tufting machine by simply fixing the vertical height of the brackets  157 , as by securing an angle iron laterally beneath the brackets when positioned in their upwardly oriented positions as shown in  FIG. 4 . Of greater interest is the use of the sliding brackets  157  in a cut/loop tufting machine, where the sliding brackets are selectively actuated to upwardly oriented positions to produce cut pile bights of yarn and retracted to downwardly oriented positions where the associated knives  47  will not cross the cutting surfaces  44  of associated hollow needles to produce loop pile bights of yarn. 
     A representative actuating system is shown in  FIGS. 4 and 7  with coupling pins  158  extending from openings  140  in the base of sliding bracket  157 . Since openings  140  extend through the base, coupling pins may be mounted with alternating rearward and forward orientations to allow more space for actuators such as double acting pneumatic cylinders  110 ,  111 . Cylinder  110  is shown with piston  114  carrying clevis  115  and clevis pin  116 . Application of air pressure to upper port  112  causes the piston  114  to retract and associated clevis pin  116  to urge lower coupling pin  158  downward, thereby moving the associated knife  47  out of cutting position resulting in a loop pile yarn bight. Similarly, application of air pressure to lower port  113  causes the piston  114  to extend and associated clevis pin  116  to urge upper coupling pin  158  upward, thereby moving the associated knife  47  into cutting position resulting in a cut pile yarn bight. 
       FIG. 7  illustrates air supply manifolds  125  supplying pressurized air or gas by ports  126  to electronically controlled valves  128 ,  129  that supply pressure by hoses  124  to ports  112 ,  113 . All of the control signals for the valves may be supplied by signals over an appropriate controller network from an electronic controller interpreting pattern data. The overall height of the cutting mechanism can also be adjusted by height control mechanism  120 , preferably servo motor driven and indexed for precise height control. Adjusting the height of the cutting mechanism alters the height of the resulting cut pile tufts and the loop pile tufts supplied at the same yarn feed rates. However, it will be appreciated that yarns for loop pile tufts are not cut at the uniform height of the intersection of the knives  47  with hollow needle cutting surfaces  44  and therefore yarns that are only to be tufted as loop pile bights may be fed at different rates. Therefore it is possible to create fabrics with cut pile bights and loop pile bights at heights resulting from yarn fed at a first feed rate, and with loop pile bights at one or more different heights resulting from yarns fed at second, and optionally third, yarn feed rates. 
     Furthermore, while in traditional operation with one of six yarns being fed selectively to a single hollow needle  40  for each stitch, the tufting machine may be efficiently operated by shifting laterally to make stitches only for about a half inch before advancing to the next row of stitches, it is also possible to have only one of twelve yarns be fed to one of two hollow needles for each stitch while the tufting machine in operated by shifting laterally to make stitches for about one full inch before advancing to the next row of stitches. Similarly, if only a single yarn of eighteen yarns available to three adjacent needles is selected for a single stitch while the tufting machine is operated laterally for about one and a half inches before advancing to the next row of stitches, or so that only a single yarn of twenty-four yarns available to four needles is fed for each stitch while the fabric is shifted laterally for about two inches before being advanced, the tufting operation will be slowed, however, the number of colors available in the tufting palette is greatly increased. If eight yarns, instead of six, were provided to each needle, the number of possible different yarns would increase from 6, 12, 18 and 24 to 8, 16, 24 and 32, providing an incredible variety of colors and textures that surpasses even the variety available in most weaving techniques. In this operation of increased lateral shifting, it is also possible to tuft more than a single yarn on a stitch to provide areas of increased yarn and stitch density in the pattern. Increased lateral shifting may also be combined with varied loop pile height stitches for greater pattern diversity. 
     All publications, patent, and patent documents mentioned herein are incorporated by reference herein as though individually incorporated by reference. Although preferred embodiments of the present invention have been disclosed in detail herein, it will be understood that various substitutions and modifications may be made to the disclosed embodiment described herein without departing from the scope and spirit of the present invention as recited in the appended claims.