Abstract:
An apparatus for removing a thread tail from a hole in a presser foot on a quilting machine. The apparatus has an orifice providing a stream of pressurized air that applies a force against a section of the thread tail extending between the needle and the hole in the presser foot. The pressurized air stream pulls the thread tail through the hole in the presser foot and gathers the thread tail on an upper side of the presser foot. In another embodiment, the present invention includes a method of automatically applying a generally transverse force to a portion of the thread tail extending between the needle and the hole in the presser foot for a duration sufficient to remove the thread tail from the hole in the presser foot.

Description:
FIELD OF THE INVENTION 
     The present invention relates to quilting machines, and particularly to an apparatus and a method of controlling a tail of a cut thread. 
     BACKGROUND OF THE INVENTION 
     In sewing machines of various types, threads are applied and manipulated on opposite sides of a fabric to form one or more patterns of stitches. The proper formation of the stitches of each series requires the cooperative movement and precise timing of cooperating stitching elements. At the end of a stitching pattern, the thread is cut; and the relative position of the fabric and the stitching elements is changed to sew another stitching pattern. Referring to FIG. 5, layers of fabric  20  to be stitched are laid out on top of a needle plate  22  of a quilting machine. A needle  24  is connected to a needle drive and mounted above a presser foot  28  in a known manner. The presser foot  28  is a bowl-type presser foot which is mounted by means of a support  29  to other components of the quilting machine in a known manner. The needle  24  and thread  25  reciprocate vertically through a hole  26  in the bowl-type presser foot  28 , through the layers of fabric  20  and then through a hole  30  of the needle plate  22 , thereby forming stitching  32  within the fabric. After a pattern has been stitched, the thread  25  is cut by a known thread cutting device (not shown) normally located below the needle plate  22 . Thereafter, the relative position between the layered fabric  20  and the needle  24 , presser foot  28  and needle plate  22  is changed to position the needle  24  with respect to the start of another pattern to be stitched. 
     As the fabric  20  is moved with respect to the needle plate  28  as shown in phantom in FIG. 5, the thread tail  34  is pulled to a location between the layered fabric  20  and the presser foot  28 . When that desired relative position between the layered fabric  20  and the presser foot  28  is achieved, the stitching cycle is again initiated, and as the needle  24  passes through the fabric  20 , the thread tail  34  remains locked under the presser foot  28 . When that stitching pattern is completed and the layered fabric again moves with respect to the presser foot, the thread tail  34  hangs from the upper surface  36  of the layered fabric  20  and requires manual trimming. 
     Therefore, there is a need to improve the process so that the manual trimming of thread tails is not required. 
     SUMMARY OF INVENTION 
     The present invention provides a method and apparatus that substantially improves the efficiency of a process of sewing layered fabric on a quilting machine. The method and apparatus of the present invention is valuable in reducing the cost of sewing layered fabric on a quilting machine by eliminating a labor intensive and time consuming manual operation. Thus, the method an apparatus of the present invention provides a more consistent, efficient and higher quality quilting machine operation and product therefrom. 
     In accordance with the principles of the present invention and the described embodiments, an apparatus is provided for removing a thread tail from a hole in a presser foot on a quilting machine. The apparatus has an orifice providing a stream of pressurized air capable of applying a force against a section of the thread tail extending between the needle and the hole in the presser foot. The pressurized air stream pulls the thread tail through the hole in the presser foot and gathers the thread tail on an upper side of the presser foot. The apparatus further has a valve for turning the stream of pressurized air on and off. 
     In another embodiment, the present invention includes a method of automatically applying a generally transverse force to a portion of the thread tail extending between the needle and the hole in the presser foot for a duration sufficient to remove the thread tail from the hole in the presser foot. 
     In one aspect of the invention, the thread tail extends through the hole in the presser foot and through the layered fabric material being sewn, and the method further comprises maintaining the pressurized air stream for a duration such that all of the thread tail is pulled from the layer fabric material and through the hole in the presser foot. 
     Thus, the apparatus of the present invention has the advantage of eliminating the labor intensive, time consuming, and expensive manufacturing operation of manually trimming hanging thread tails from the sewn fabric. The apparatus of the present invention controls the thread tail in a manner that permits the thread tail to be sewn into the layered fabric during a further stitching operation. 
     Various additional advantages, objects and features of the invention will become more readily apparent to those of ordinary skill in the art upon consideration of the following detailed description of the presently preferred embodiments taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a partial sectioned perspective view of a presser foot and other stitching elements of a quilting machine in accordance with the principles of the present invention. 
     FIG. 2 is a partial top view of the presser foot of FIG. 1 with a thread tail beneath the presser foot. 
     FIG. 3 is a partial top view of the presser foot of FIG. 1 with the thread tail removed from beneath the presser foot. 
     FIG. 4 is a cross-sectional view taken along line  4 — 4  of FIG.  3 . 
     FIG. 5 is a partial sectioned perspective view of a prior art presser foot and other stitching elements of a quilting machine. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, as the layered fabric  20  changes position with respect to the presser foot  28 , the thread tail  34  is captured between a lower surface  35  of the presser foot  28  and the top surface  36  of the layered fabric  20 . As previously discussed, in the absence of the invention, subsequent stitching by the needle  24  will result in the thread tail  34  hanging from the surface  36 . Thus, with each pattern stitched, the thread tail  34  must be manually trimmed and removed. 
     In order to eliminate the hanging thread tail  34 , the present invention utilizes an air jet from an orifice  40  at one end of a tube  42 . As shown in FIG. 2, the orifice  40  of the tube  42  is oriented to direct a stream of pressurized air  43  substantially diametrically across the hole  26  of the presser foot  28 . The tube  42  has a nominal inside diameter of 0.0625 inches and is made from any suitable material, for example, a malleable soft copper, brass, steel, plastic, etc. The other end of the tube  42  is connected to a valve  45  that, in turn, is fluidly connected to a source of pressurized air  47 . The operation of the valve  45  is controlled by a quilting machine control  49  as will be subsequently described. The pressurized air stream from the orifice  40  applies a sufficient force on the thread  34  to move the thread tail  34  to a location on an upper side of the presser foot  28 . The pressurized stream of air  43  is maintained for a sufficient duration to pull the full length of the thread tail  34  upward through the hole  26  of the presser foot  28 . 
     Referring to FIGS. 2-4, a baffle  46  is mounted on the presser foot  28 . The baffle  46  has an outer edge  52  with an arcuate profile that matches the circular profile of the outer peripheral edge  54  of the presser foot  28 . The baffle  46  has an inner edge  53  that is substantially linear and extends between the ends  48 ,  50  of the outer edge  52 , thereby forming a substantially crescent-shaped baffle  46 . The baffle  46  is attached to the peripheral edge  54  of the presser foot  28  at the ends  48 ,  50  by an appropriate process, for example, welding, brazing, etc. Thus, referring to FIG. 4, the arcuate edge  52  of the baffle  46  is unattached to, and forms a small gap  55  with, the peripheral edge  54  of the presser foot  28 . The gap  55  is, for example, approximately 0.030 inches. Consequently, the gap provides a path for the pressurized air stream  43  from the orifice  40  in a manner to facilitate the lifting of the thread tail above the presser foot  28 . 
     In the illustrated embodiment of FIGS. 2-4, the baffle plate is mounted on the peripheral edge  54  of the presser foot  28  such that the inner edge  53  of the baffle plate  46  forms an angle a of approximately 9° rotated counterclockwise from a first diameter  57  coincident with a centerline of the mounting bracket  29 . The tube  42  is mounted within the presser foot  28  such that the pressurized air stream is directed out of the orifice  40  at an angle β of approximately 5° rotated counterclockwise from a second diameter substantially perpendicular to the first diameter. It should be noted, however, that those angles are not critical to the operation of the invention. Normally, the pressurized air stream from the orifice  40  should be directed along a path that is approximately perpendicular to the inner edge of baffle plate  46 . 
     Care should also be taken that the pressurized air stream does blow the thread  25  out of the eye  23  from the needle  24  (FIG.  1 ). Therefore, the pressurized air stream from the orifice  40  should be directed at the needle  24  in the same direction as the thread  25  passes through the needle. In other words, the pressurized air stream from the orifice  40  should be directed generally at the side of the eye  23  of the needle  24  that receives the thread  25 . 
     The baffle  46  functions to direct the pressurized air stream across the presser foot  28  in a direction moving the thread tail  34  to the interior of the presser foot  28  as shown in FIGS. 3 and 4. Hence, the thread tail  34  is loosely gathered on top of the presser foot  28  and is not locked between the lower surface  35  of the presser foot  28  and the upper surface  36  of the layered fabric  20 . Therefore, when stitching is again initiated, the needle  24  sews both the thread  25  and the thread tail  34  into the layered fabric  20 . Thus, the thread tail  34  is sewn into the layered fabric  20  and there is no requirement for trimming the thread tail  34  after the pattern is stitched. Referring to FIG. 4, normally, the orifice  40  at the end of the tube  42  is uncut in a plane having an angle φ of approximately 30° with the bottom surface  44  of the presser foot  28 . 
     In use, the process of capturing the thread tail  34  on the upper side of the presser foot  28  is commanded by the quilting machine control  49  and is executed in association with a trim cycle that cuts the thread  25  in a known manner. At substantially the same time that the quilting machine control  49  provides an output signal to a knife commanding the knife to cut the thread, the quilting machine control  49  provides a signal over an output  51  to a valve  45 , for example, an electrically operated solenoid valve, causing the valve  45  to switch to an open state. In the open state, the valve  45  permits the pressurized air to flow from the source  47  through the fluid path formed by the tube  42  and out the orifice  40 . A timer within the quilting machine control  49  is also started so that the valve  45  remains open for a period of time, for example, 2-5 seconds. The pressure magnitude of the pressurized air and the duration of the timer must be sufficient to allow the force of the air stream  43  on the recently cut thread tail  34  to pull the full length of the thread tail  34  through the layered cloth  20  and the hole  26  of the presser foot  28 . When the timer in the control  49  expires, the quilting machine control  49  switches the state of the signal on its output  51 , thereby switching the state of the valve  45  and terminating the flow of pressurized air from the source  47  and out the orifice  40  of the tube  42 . Therefore, when the machine starts its next stitching cycle, the cut thread tail  34  is not trapped by the presser foot, but instead, is gathered loosely on top of the presser foot  28 . And, the needle  25  sews the thread tail  34  into the layered fabric  20 , leaving no tail from the top surface  36  and only a small knot on the opposite side of the fabric. 
     The pressurized air stream  43  of the present invention moves the thread tail to a location in which the tail  34  is not clamped by the presser foot  28 , but is free to be sewn in the layered fabric by subsequent stitching. By maintaining such control of the thread tail, the labor-intensive, time-consuming and expensive process of having to manually trim thread tails from each of the patterns stitched is eliminated. Thus, the invention reduces the labor content, the time of manufacturing, and it presents a substantial cost savings to the manufacturer. 
     While the present invention has been illustrated by a description of one embodiment and while that embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the invention will readily appear to those skilled in the art. For example, in the described embodiment, the thread tail  34  is removed from the fabric at the end of a stitching pattern and before the relative position between the layered fabric  20  and the presser foot  28  is changed. Obviously, it is easier to move the thread tail  34  to the upper side of the presser foot prior to the thread tail becoming pulled beneath the presser foot  28 . However, as will be appreciated, the thread tail may be moved at a different time in the stitching cycle, and the thread tail may be also pulled from between the lower side of the presser foot and the upper surface of the layered fabric. 
     Further, in the described embodiment, the presser foot  28  is shown and described as a bowl-type presser foot. As will be appreciated, the invention is applicable to other types of a presser foot, for example, a flat presser foot. Regardless of its design, the presser foot should have a size that permits the thread tail to be moved to the top of the presser foot, so that it is not subject to being trapped between a lower side of the presser foot and the fabric. In addition, while the described embodiment shows a single needle, as will be appreciated, the thread tail control of the present invention may be applied to machines having any number of needles. 
     In addition, the orifice  40  is described as being circular. As will be appreciated, the orifice  40  may be elliptical or any other geometric shape. Further, in the described embodiment, the orifice  40  is described as having a nominal inside diameter of 0.0625 inches. However, as will be appreciated, the orifice  40  may be smaller or larger. 
     The described embodiment recites specific values for the angles α, β, φ, the gap between the baffle plate outer edge  52  and the peripheral edge  54  of the presser foot  28  and the time duration of the air stream. As will be appreciated those are values that have been chosen for a presser foot of a specific design in a particular application. Depending on the size and geometry of the presser foot  28  and other application related conditions, other values for those variables may be used; and further, some experimentation with respect to those variables may be required to achieve the desired results. 
     The invention is particularly suitable for use on multi-needle quilting machines such as described, for example, in commonly assigned U.S. Pat. Nos. 5,154,130 and 5,544,599, hereby expressly incorporated herein by reference. The invention is also useful on single needle quilting machines as, for example, described in commonly assigned U.S. Pat. Nos. 5,650,916, 5,685,250 and 5,832,849, hereby expressly incorporated by reference herein. The thread tail control is particularly suited for use at the start of the quilting of a pattern. 
     Therefore, the invention in its broadest aspects is not limited to the specific detail shown and described. For example, the invention may be useful in other non-quilting sewing applications. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.