Patent Document

FIELD OF THE INVENTION  
       [0001]     The present invention relates to sewing machines and, more particularly, to sewing machines adapted to sew binding material onto carpet edges.  
       BACKGROUND OF THE INVENTION  
       [0002]     Carpet binding machines are used to sew binding material, or tape, to the top and bottom of a piece of carpet to bind the edge of the carpet. Oftentimes, in a wall-to-wall carpet installation, a four or six inch strip of contrasting carpet will be used as coving instead of wood or rubber cove molding. In such an installation, the upper edge of the carpet cove needs binding material sewn thereon to present a finished appearance and so that the edge does not unravel. The stitch utilized by most carpet binding machines is the federal stitch type  401  chain stitch because of its streamlined appearance and effective binding capability.  
         [0003]     Carpet binding machines are generally classified as being portable or stationary. Stationary machines are heavy, often weighing between 55 and 65 pounds. The weight of such machines forces them to be used at a single location, for example, in a carpet installer&#39;s warehouse, to sew binding material onto a carpet edge. While such machines tend to be durable, their lack of portability limits their usefulness in situations where the carpeting cannot be precut into appropriate length pieces for the job and bound in the installer&#39;s warehouse. Also, such stationary machines tend to be costly compared to their portable counterparts.  
         [0004]     Portable carpet binding machines have the advantage of being capable of being transported and used at installation sites by installers. They do not require the carpeting to be precut and prebound as with a stationary machine and are lower in cost than stationary machines. However, the durability and reliability of most prior art portable carpet binding machines has been unsatisfactory.  
         [0005]     Portable carpet binding machines are manufactured by modifying a standard household sewing machine. While such sewing machines are suitable for sewing clothes and similar light fabrics, subjecting such machines to the rigors of sewing carpeting characterized by heavy backing material and a plush pile results in an undesirable rate of skipped or otherwise malformed stitches, carpet feed problems, or even sewing machine breakdowns.  
         [0006]     A skipped or malformed stitch can be corrected at the installation site. However, because such problems recur with frequency, oftentimes taking the time to restitch a piece of carpet can result in substantial delays and inconvenience.  
         [0007]     A skipped stitch may occur in a type  401  stitch sewing cycle, for example, if the needle loop is not properly formed and the looper misses the opening of the needle loop as a result. Because portable carpet binding machines typically use a plastic needle thread, there is a greater tendency for the needle thread to flex in an unpredictable manner and, therefore, create unpredictable sewing results. Oftentimes, a single skipped stitch will cause the succeeding stitch to be missed because the previously improperly formed needle loop generates additional slack in the needle thread making it difficult to form the next needle loop. A series of missed stitches can cause an unsightly gap in the stitching of the binding material and a risk of the carpet edge unraveling.  
         [0008]     A malformed stitch may occur, for example, if there is too much slack in the needle thread or looper thread. A household sewing machine incorporates thread take-up mechanisms to remove slack in the threads. These thread take-up mechanisms, however, are not designed to be used in a portable carpet binding machine. Some prior art portable carpet binding machines that modify such household sewing machines fail to adequately modify the thread take-up mechanism, which, in turn, can cause such malformed stitches.  
         [0009]     A malformed stitch can also occur when the piece of carpet is not fed properly through the sewing machine. Portable carpet binding machines that are made from a modified household sewing machine utilize what is known in the art as a presser foot and feed-dog to feed the carpet. It has been found that this single feed assembly is unsatisfactory for feeding a piece of carpet. Furthermore, the rigors of carpet binding may subject components of the machine to undue stress and cause excessive wear or failure in the components.  
         [0010]     Since most carpet installers can only afford a single carpet binding machine, a breakdown of the machine requires the installer to quit working on the installation, take the machine to a repair shop, procure needed repairs and then return to the installation site to finish the job. The downtime of a portable carpet binding machine, whether due to restitching or repairing, results in downtime of the installer in addition to the expense of repair of the machine. Since most installers are paid by the job, downtime has a direct impact on the number of jobs completed by the installer and his or her net income.  
         [0011]     Because of the thickness and stiffness of the carpet being bound, another problem with prior art carpet binding machines is their tendency to pull or angle away from the carpet edge while the machine moves along the carpet. This is typically caused by an insufficient carpet feeding assembly and results in poor appearance of the resulting bound carpet edge. When the binding machine angles away from the carpet edge as is moves along the carpet, the stitching and binding material are angled with respect to the edge of the carpet. Moreover, instead of the binding material being snugly pulled and stitched around the edge of the carpet, excess binding material gathers loosely around the carpet edge providing an unsightly appearance and poor durability.  
         [0012]     One portable carpet binding machine that represented a significant advance in the art was the machine disclosed in U.S. Pat. No. 5,875,723 to Lobur. The &#39;723 patent is incorporated herein in its entirety by reference. The &#39;723 patent disclosed a portable carpet binding machine that included a novel carpet feeding assembly with a feed driver mechanism and coacting puller mechanism acting in synchronization to pull the carpet through the sewing mechanism.  
         [0013]     While the carpet binding machine disclosed in the &#39;723 patent proved to be a lightweight, yet rugged and durable machine, certain improvements were desirable to further improve the feed drive mechanism such that even the heaviest and thickest carpet would be pulled linearly through the sewing mechanism and the machine would not tend to pull away from the edge of the carpet.  
         [0014]     What is needed is a portable carpet binding machine that is adapted to sewing light or heavy pile carpeting and that includes a carpet feeding assembly that feeds the carpet linearly through a sewing assembly and that moves the machine uniformly along an edge of the carpet. What is further desired is an upper direct drive mechanism within close proximity to the existing puller mechanism, wherein the upper direct drive mechanism is capable of vertical movement to compensate for varying thicknesses in the carpet material. It is desirable to accomplish such vertical movement of the upper drive mechanism through a direct connection with a minimal number of parts, such as universal joints, linkages, and bushings, which increase the cost of the machine and decrease efficiency. What is also needed is a portable carpet binding machine that is lightweight and that is more durable and reliable than prior art portable carpet binding machines. Such a machine must also be easy to manufacture and repair and be competitively priced with prior art portable carpet binding machines.  
       SUMMARY OF THE INVENTION  
       [0015]     The present invention is directed to a portable carpet binding machine that is adapted to bind binding material, or tape, to the edge of light or heavy carpeting. The portable carpet binding machine is durable, lightweight (weighing about 18 pounds) and is easy to manufacture using known manufacturing techniques. Its design also facilitates easy repair of worn out or damaged working components of the machine.  
         [0016]     The portable carpet binding machine includes a housing defining an interior region. The housing supports two rolls of thread and a coil of binding material. A distal end of the first roll of thread is threaded through a needle of the sewing assembly while a distal end of the second roll of thread is threaded through a looper of the sewing assembly. The binding material is sewn to the top and bottom to bind the edge of the piece of carpet using a chain stitch known as a federal stitch type  401  double locked chain stitch to those skilled in the art.  
         [0017]     The housing is supported on rollers permitting the machine to move with respect to a stationary piece of carpet to be bound. Alternately, if the piece of carpet to be bound is relatively small, the carpet binding machine may be held stationary and the carpet fed through the machine.  
         [0018]     Extending from the housing is also a handle to aid in positioning the machine as desired and carrying the machine between locations at an installation site. The housing supports a finger trigger switch for activating the drive mechanism. Advantageously, the trigger switch can be locked into an “on” position and a microswitch is provided for actuating the machine when carpet is fed into the sewing assembly.  
         [0019]     A drive mechanism is supported by the housing and at least partially disposed in the interior region. A prime mover is operatively coupled to the drive mechanism for providing motive power to the drive mechanism. In the preferred embodiment, the prime mover comprises an AC 60 watt series motor. In the preferred embodiment, a potentiometer is operative to vary the speed of the prime mover and, consequently, the speed of the drive mechanism.  
         [0020]     The drive mechanism drives a sewing assembly. The sewing assembly is operative to sew a strip of material to a piece of carpet. The sewing assembly includes a binder guide, a sewing needle and a looper. The binder guide operates to fold the strip of material around an edge portion of the piece of carpet. A first piece of thread is threaded through an aperture of the needle and a second piece of thread is threaded through an aperture of the looper. The sewing assembly, when driven by the drive mechanism, is operative to stitch the strip of material to opposite sides of the edge portion of the piece of carpet using the first and second pieces of thread.  
         [0021]     The present invention also includes a carpet feeding assembly. The carpet feeding assembly includes a feed driver mechanism and a coacting puller mechanism that operate in substantially synchronous movement to linearly feed the piece of carpet relative to the sewing assembly. The feed driver mechanism includes a feed-dog that is driven by the drive mechanism and that intermittently engages the bottom of the piece of carpet, which, in turn, advances the piece of carpet forward.  
         [0022]     The coacting puller mechanism includes a first feed roller disposed above the feed-dog so that the piece of carpet is engaged between the feed-dog and the first feed roller when the carpet is advanced. The first feed roller is biased by a spring to provide a downward force against the top of the piece of carpet. The second feed roller is driven by the drive mechanism to pull the piece of carpet forward substantially simultaneously with respect to advancement of the piece of carpet by the feed-dog.  
         [0023]     The coacting puller mechanism further includes a second feed roller located downstream of the feed-dog. Like the first feed roller, the second feed roller is driven by the drive mechanism. The second feed roller engages the bottom of the piece of carpet and pulls the piece of carpet forward substantially simultaneously with respect to the advancement by the feed-dog and the first feed roller.  
         [0024]     The coacting puller further includes a presser roller, which is disposed above the second driven roller. The presser roller provides a downward force opposite the second feed roller so that the piece of carpet is engaged therebetween. A spring biases the presser roller downwardly.  
         [0025]     The first and second feed rollers also comprise a helical profile on their outer surface. The helical profile advantageously produces a force that pulls the carpet inward relative to the sewing assembly. The helical profile increases the quality of the stitch, as well reduces the effort required by the operator of the carpet binding machine in maintaining a linear feed of the carpet into the machine.  
         [0026]     The first feed roller and feed-dog are driven by a single piece drive mechanism that comprises an integral first and second eccentric cams for advancing the carpet through the sewing assembly. Such integral configuration help reduce breakdowns in the equipment while increasing the quality of the stitching. The single piece drive mechanism further comprises a third eccentric cam that is removably attached to the shaft that is used to drive the second feed roller.  
         [0027]     Additional features will become apparent and a fuller understanding obtained by reading the following detailed description made in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  is a perspective view with a cut-away portion of the portable carpet binding machine of the present invention shown sewing binding material to a strip of carpeting;  
         [0029]      FIG. 2  is a front elevation view of the portable carpet binding machine of  FIG. 1  showing upper and lower feed rollers;  
         [0030]      FIG. 3  is a left side view, partly in section and partly in elevation, of the portable carpet binding machine of  FIG. 1  showing a drive mechanism for an upper feed roller  
         [0031]      FIG. 4  is a left side view, partly in section and partly in elevation, of the portable carpet binding machine of  FIG. 1  showing a drive mechanism for a lower feed roller;  
         [0032]      FIG. 5A  is a front view, partly in section and partly in elevation, of the portable carpet binding machine of  FIG. 1  showing a rocker arm that drives the lower feed roller;  
         [0033]      FIG. 5B  is a front view, partly in section and partly in elevation, of the portable carpet binding machine of  FIG. 1  showing a unidirectional clutch and a rocker arm that drives the lower feed roller shaft;  
         [0034]      FIG. 5C  is a sectional view of the portable carpet binding machine of  FIG. 1  showing the drive mechanism for the upper feed roller;  
         [0035]      FIG. 6  is a perspective view of a single piece drive shaft of the portable carpet binding machine of  FIG. 1  that drives a feed-dog and upper and lower feed rollers;  
         [0036]      FIG. 7A  is an elevation view of a looper drive mechanism of the portable carpet binding machine found in the prior art in a first position; and  
         [0037]      FIG. 7B  is an elevation view of the looper drive mechanism of the portable carpet binding machine of  FIG. 1  in a second position.  
     
    
     DETAILED DESCRIPTION  
       [0038]     A portable carpet-binding machine of the present invention is shown generally at  10  in  FIG. 1 . To describe the features of the present invention the illustrated embodiment shows a Newlong Model NP-3II portable bag-closing machine with modifications thereto. However, it should be understood by those skilled in the art that the present invention is adaptable to any type of sewing machine.  
         [0039]     The machine  10  is shown binding a cut edge  11  of a piece of carpet  12 . The binding process involves sewing a binding material  14  to the top  15  and bottom  16  of the piece of carpet  12  so that the binding material  14  overlies the cut edge  11  of the piece of carpet  12 . Typically, the binding material  14  is ⅞ inch wide but can vary from ¾ inch to 3 inches. The carpeting  12  is a strip four to six inches in width. Such a carpet strip  12  is used for coving in a wall-to-wall carpet installation, but it should be understood that the machine  10  will function to sew binding material to a peripheral edge of any size piece of carpet  12 .  
         [0040]     The machine  10  includes a housing  20  and an AC motor  22  attached to and extending from the housing  20 . A drive belt  34  is driven by a pulley shaft  36  of the motor  22 . The housing  20  supports a driven pulley  38  and a handle  30  used to position the machine  10  and carry the machine  10  between job locations.  
         [0041]     The housing  20  supports a drive mechanism  40  that includes the driven pulley  38  and a single piece drive shaft  46  affixed to the pulley  38 . As can be seen in  FIGS. 3 and 4 , the drive shaft  46  is supported near its front  41  and rear  42  by bushings  51 ,  52 . The single piece drive mechanism  40  is driven by the motor  22  (shown in  FIG. 1 ) via drive belt  34  and pulley  38  and provides motive power to a sewing assembly generally designated as reference character  100  ( FIG. 1 ), and a carpet feeding assembly generally designated as reference character  200  ( FIGS. 3 and 4 ).  
         [0042]     A detailed drawing of the single piece drive shaft  46  is shown in  FIG. 6 . The drive shaft  46  preferably is turned from a single piece of bar stock and formed integrally on the shaft is a first eccentric cam  43  and second eccentric cam  44 . Because of the position of the first and second cams  43 ,  44  being exterior to or outside of the region between the bushings  51 ,  52 , the drive shaft  46  of the present invention advantageously is a one piece drive shaft. By contrast, in prior art drive shafts, at least one of the cams was in the region between the shaft bushings and, therefore, in order to remove the drive mechanism  40  from housing  20 , the cam between the bushings had to be capable of being disengaged from the shaft.  
         [0043]     Because the design of the present invention locates first eccentric cam  43  to the outside of bushing  52 , that is, toward a front F of the machine  10 , a single piece shaft drive mechanism can be used. The single piece shaft drive mechanism is advantageous in several respects. First, single piece shaft drive mechanism avoids timing problems often seen in the prior art because the single piece design will not have cams held in place by set screws which are prone to becoming loosened over time with the vibration of the machine. Second, space saving resulting from the relocation of the first eccentric cam  43  outside of the bushings advantageously permits two motor driven puller mechanisms  201 ,  221  to the feeding assembly  200  instead of a single puller mechanism utilized in the prior art. The addition of a second puller mechanism insures a linear feed of the carpet through the sewing assembly  100  regardless of the thickness of the carpet and mitigates the tendency of the carpet  12  to pull away from the machine  10  (or the machine to pull away from the carpet) as the machine  10  is progresses along the edge  11  of the carpet  12  to sew the binding material  14  to overlie the carpet edge  11 .  
         [0044]     The sewing assembly  100  includes a sewing needle  102  for introducing a needle thread  103 , a binder guide  104  for introducing binding material  14 , and a looper  106  (shown in  FIG. 1  and  FIG. 7 ) for introducing a looper thread  107 . The threads  103 ,  107  are supplied via a needle thread spool  122  and a looper thread spool  124 , respectively (see  FIG. 1 ).  
         [0045]     As can be seen in  FIG. 1 , the sewing needle  102  is connected to a reciprocating rod  108  mounted in an extending arm portion  24  of the housing  20 . The rod  108  effects upward and downward movement of the needle  102 . Reciprocal motion of the rod  108  is driven and controlled by a lever and connecting rod assembly (not shown) driven by the drive mechanism  40 . In operation, one revolution of the drive mechanism  40  effects a full upward and downward stroke, or cycle, of the sewing needle  102 .  
         [0046]     In operation, as the carpet  12  is advanced by the carpet feeding assembly  200  (partially shown in  FIGS. 2, 3 , and  4 ), the sewing assembly  100  operates to stitch the binding material  14  simultaneously to a top  15  and a bottom  16  of the piece of carpet  12  by what is known in the art as a type  401  double locked chain stitch.  
         [0047]     The carpet feeding assembly  200  includes the two coacting puller mechanisms, generally indicated as reference characters  201  and  221  and a feed-dog  240 , which operate in synchronized movement to feed the piece of carpet  12  relative to the sewing assembly  100 .  
         [0048]     The presence of two coacting puller mechanisms  201  and  221  provide significant advantages over the single puller mechanism of the prior art. Both puller mechanisms  201  and  221  act cooperatively with one another and the feed-dog  240  to pull the carpet  12  through the sewing assembly  100 . One of the advantages of having two puller mechanisms  201  and  221  is that the carpet can be more easily fed through the sewing assembly  100 , reducing the number of malformed stitches. The operator also expends less energy making said operator more productive during the sewing operation. Yet another benefit is the reduction in stress on the components of the feeding assembly, resulting in a decrease in breakdowns, loosening of detail connections, and a reduction in the number of service calls.  
         [0049]      FIG. 4  shows the lower coacting puller mechanism  201 . The puller mechanism  201  includes a bottom-mounted or lower motor-driven feed roller  203  with a helical profile  214 , a rocker shaft  204 , and a rocker arm  211  comprising a cam follower path  213 . Mounted on the extending upper arm  24  of the housing  20  is a presser roller  202 . The presser roller  202  is biased downwardly, via a spring  205 , against the upper surface  15  of the carpet  12 . The carpet  12  is firmly gripped or engaged between the upper presser roller  202  and the bottom-mounted feed roller  203 . The lower feed roller  203  is downstream, that is, the direction D in  FIG. 2 , of the feed-dog  240  and the upper puller mechanism  221  and it rotates in synchronization with movement of the feed-dog  240  and rotation of the upper puller mechanism  221  to feed the carpet  12  through the sewing assembly  100 , which is fed by rotation of the lower feed roller  203 .  
         [0050]     As the lower feed roller  203  rotates, the presser roller  202  rotates in a direction opposite the lower feed roller  203 , and both rollers in a coacting fashion pull the carpet  12  through the sewing assembly  100 . A presser roller adjusting mechanism  206  maintains a predetermined amount of down force on the presser roller  202 .  
         [0051]     The lower feed roller  203  is fixedly attached to a rocker shaft  204  and comprises a helical profile  214 . The rocker shaft is supported near its front  207  and rear  208  by bushings  209  and  210  respectively. The motor driven roller  203  is intermittently rotated by the rocker arm  211 . When viewed in  FIG. 5B , the counterclockwise rotation of the first eccentric cam  43  generates both clockwise and counterclockwise rotation of the rocker arm  211 . The uni-directional clutch  212  is fixedly attached to the rocker arm  211 , which engages the rocker shaft  204  when rotated counterclockwise and disengages the rocker shaft when rotated clockwise, as depicted by the arrows in  FIG. 5B .  
         [0052]     Rocker arm  211  comprises a cam follower  213  that engages the first eccentric cam  43 . The clockwise and counterclockwise rotation of the rocker arm  211  is a result of the profile of the first eccentric cam  43  and the configuration of the cam follower  213 . Modification of the first eccentric cam  43  or the cam follower  213  will change the amount of rotation resulting in the rocker arm  211 . Because of the uni-directional clutch  212 , the rocker shaft  204  is intermittently rotated in a counterclockwise direction as described above. The bottom mounted roller  203  is fixedly attached to the rocker shaft  204 , which also rotates intermittently in a counterclockwise direction. The counterclockwise rotation of the lower feed roller  203  pulls the carpet  12  by engaging the carpet bottom  16 . Facilitation of the pulling process occurs through the synchronized rotation of the lower feed roller  203  and the clockwise rotation of the presser roller  202 , on the carpet  12  therebetween. The presser roller  202  engages the top portion  15  of the carpet  12 . The spring  205  asserts an axial force downward through the presser roller  202  onto the carpet  12 , thereby ensuring the engagement of both the presser roller and the lower feed roller  203  to the carpet as its pulled through the sewing assembly  100 . The amount of axial downward force can be varied through a presser roller adjusting mechanism  206 .  
         [0053]     As can best be seen in  FIG. 4 , the lower feed roller  203  and the top mounted presser roller  202  include a helical profile or outer surface  214  and  217 , respectively. The exemplarily embodiment shows the helical profile of  214  to resemble a left-handed thread configuration and helical profile  217  comprises a right-handed configuration. This forces the carpet  12  to be drawn inward, that is, in the direction I in  FIGS. 3 and 4 , relative to the carpet feeding assembly  200  because of the axially-transverse thrust generated by the left-handed helical profile  214 , and the counterclockwise rotation of the bottom mounted motor driven roller  203  along with the axially-transverse thrust generated by the right-handed helical profile  217 , and the clockwise rotation of the top mounted presser roller  202 . The helical profiles then reduce the amount of effort required by the operators during the sewing process, since the carpet  12  has a tendency to pull away from the sewing assembly  100  during sewing as the machine  10  moves along the carpet edge  11 . The feed roller profiles used by the prior art resemble a spur or spline configuration, which exacerbates the carpet&#39;s tendency to pull away from the machine, because of such profiles inherent lack of resistance. In addition, the prior art lacks the axially transverse thrust generated by the described invention. The helical profiles  214  and  217  can also contain breaks in the threads resembling crenellated rows or teeth along a left-hand or right-handed thread path.  
         [0054]     The coacting puller mechanisms  201  and  221  are not only designed to achieve proper kinematic motion, but also to operate harmoniously with other linkages, levers, cams, shafts, and followers within a limited amount of space defined by the housing  20 . The described invention makes best use of the limited space through the unique designs of the rocker arm  211 , uni-directional clutch  212 , cam follower  213 , and first eccentric cam  43  located between the internal housing flange  21 , as shown in  FIG. 4 , and the feed-dog  240  and lifter  241  shown in  FIG. 3 .  
         [0055]     The design of the present invention advantageously provides a ⅜ inch cavity to accommodate the location of the rocker arm  211  and the first eccentric cam  43 . The design was accomplished without the need of any additional linkages or universal joints. The present invention maintains the configuration of the feed-dog  240  and feed-dog lifter  241  disclosed in the &#39;723 patent. This reduces the cost of production by using standard components. Yet another advantage of the present invention is that it incorporates a direct drive between the second eccentric cam  44  and feed-dog lifter  241 , thus preventing any loss of motion that would occur through the use of additional linkages or universal joints.  
         [0056]     Relocating coacting puller mechanism  201  toward the front F of the housing  20  not only permits a single piece drive mechanism  40 , but also enables the addition of the second upper coacting puller mechanism  221  to the mid-section  54  of the single piece drive mechanism  40 , as shown in  FIGS. 3 and 4 . The upper coacting puller mechanism further reduces the amount of effort expended by the operator during a sewing operation, since the carpet  12  can now be more easily fed through the sewing assembly  100 . As well, there is a reduction in the opposing forces on the components of the puller mechanisms, thereby making the details less susceptible to breaking or working loose. In addition, the second motor driven puller mechanism  221  reduces carpet slippage and the malformed stitches, which would result from such slippage.  
         [0057]     Referring more closely to  FIGS. 3, 5A , and  5 C the upper coacting puller mechanism  221  comprises an eccentric cam  224 , a connecting rod  225 , rocker arm  226 , a housing  222 , and an upper motor-driven feed roller  223  with a helical profile  232 . The upper coacting puller mechanism  221  works in synchronization with the feed-dog  240  and the lower puller mechanism  201 . The eccentric cam  224  is fixedly attached to single piece shaft  46  between front bushing  51  and rear bushing  52 . As can be seen in  FIG. 6A , a flat region  45  near a center of the shaft  46  is adapted to be engaged by a set screw which fixes the cam  224  in place with respect to the shaft. Driven by the profile of the eccentric cam  224  is the connecting rod  225 , which translates about the drive shaft  46 . The connecting rod  225  is rotatably connected to the rocker arm  226  via pin  231 . The translation in the connecting rod  225  forces the rocker arm  226  to rotate in both a clockwise and counterclockwise direction. The rotation of the rocker arm  226  creates a ratcheting effect on the upper rocker shaft  227 . This allows intermittent rotation of the rocker shaft in a clockwise direction as viewed from  FIG. 5A , while remaining idle when the rocker arm  226  is rotated in a counterclockwise direction. The rocker shaft  227  is supported by bushings  229  and  230  press fit within the roller housing  222 . The ratcheting effect on the rocker shaft  227  is accomplished through a uni-directional clutch  228  fixedly attached to the rocker shaft  227 .  
         [0058]     In order to accommodate varying thicknesses of the carpet material the upper motor driven roller  223  must be capable of vertical movement, while at the same time able to rotate pulling the carpet  12  through the sewing assembly  100 . As best can be seen in  FIGS. 2 and 3 , relative vertical movement of the straight shaft  227  and the drive shaft  46  is provided by the pivotal connection between the connecting rod  225  and rocker arm  226 . As the straight shaft  227  moves vertical with respect to the drive shaft  46  and a throat plate  242  of the feed-dog  240 , the shaft  227  remains parallel to the drive shaft  46 . This eliminates the use of universal joints and linkages that are typically required to obtain this dual acting motion. The current invention allows for both rotation and translation through the use of only the straight shaft  227  and rocker arm  226 . Manual vertical movement of the upper feed roller  223  is also permitted by a manually activated lever that is coupled to a roller rod  233  and the roller housing  222 .  
         [0059]     The rotation of the upper feed roller  223  occurs once per sewing cycle, where one revolution of the drive shaft  46  causes an oval-type movement the feed-dog  240  and a clockwise rotation of the top-mounted motor driven roller  223  to act in concert to engage and pull the carpet  12  through the sewing assembly  100 . The feed-dog  240  operates to engage the bottom  16  of the piece of carpet  12  through the lifter  241 , which is driven by the second eccentric cam  44  located on the drive shaft  46 . The second eccentric cam  44  and the lifter together control the rise and fall of the feed-dog  240 . The feed-dog  240  moves in both the horizontal and vertical directions in a generally oval path. When the feed-dog  240  rises above an upper surface of the feed-dog throat plate  242  ( FIGS. 1 &amp; 5A ) and engages the bottom surface  16  of the carpet  12 , it then moves generally horizontally in the downstream direction D to move the carpet  12  in the downstream direction D. The length of the path of travel of the feed-dog  240  in the downstream direction D while above the throat plate  242  will determine the length of each stitch. At the same time the feed-dog  240  is moving above the throat plate  242  in the direction D, the upper feed roller  223  rotates in a clockwise direction CW (as seen in  FIG. 2 ) and the lower feed roller  203  rotates in a counterclockwise direction CCW (again, as seen in  FIG. 2 ) in appropriate rotational amounts to match the linear distance the feed-dog  240  moves the carpet  12  downstream D. To complete its oval path, the feed-dog  240  at the end of path of travel downstream D falls vertically below the throat plate  242  (out of contact with the carpet  12 ) and moves horizontally upstream (opposite the direction D) while remaining below the throat plate  242 .  
         [0060]     The top mounted motor driven roller  223  also comprises a helical profile  232  that resembles a right-handed thread configuration. The carpet  12  is then drawn inward direction I (see  FIGS. 3 and 4 ) relative to the carpet feeding assembly  200  because of the axially-transverse thrust generated by the right-handed helical profile and the clockwise rotation of the top mounted motor driven roller  223 .  
         [0061]     The helical profile in the top mounted motor driven roller  223  like that in the bottom mounted motor driven roller  203  reduces the amount of effort expended by the operators during the sewing process, since the carpet  12  has a natural tendency to pull away from the sewing assembly  100 . There exists a natural tendency to pull away because, inter alia, the majority of the carpet&#39;s weight is outside of the feeding assembly  200 . The helical profile as discussed above can comprise any number of different configurations, including continuous threads, or crenellated rows or teeth along a left-hand or right-handed thread path.  
         [0062]     A predetermined amount of downward force is applied to the carpet  12  through the top-mounted feed roller  223  by way of the housing  222  and the roller rod  233 . The amount of down force applied to the roller rod can be varied by changing the location of an adjustment mechanism  235  relative to a spring  234 . The amount of axial down force varies the force of engagement between the upper feed roller  223  and the feed-dog  240  with the carpet  12  when the feed-dog  240  is in an upward position, that is engaged and moving the carpet in the downstream direction D. When the feed-dog  240  is not in its upward position, that is, the feed-dog is recessed below openings in a feed-dog throat plate  242 , the carpet  12  is engaged between the throat plate  242  and the upper feed roller  223 . The axial down force also acts in conjunction with the helical profile  232  to force the carpet  12  down and inwardly (in the direction I) as it moves through the sewing assembly  100 , opposed to the natural tendency to pull up and away from the housing  20 . This again reduces the amount of energy required by the operator in using the carpet-binding machine  10 .  
         [0063]     Another enhancement of the present invention is shown in  FIGS. 1 and 7 B, which is a retractable linkage in the looper assembly  250 . The looper  106  uses looper thread  107  in making among others, a type  401  double locked chain stitch as discussed above. One of the inherent problems in any sewing operation is rethreading the looper when the looper thread  107  runs-out or breaks during operation. Rethreading the looper requires significant time as the looper thread  107  must be hand fed through a first aperture  252  located at the heel  251  of the looper up through a second aperture  253  located in the front  254  portion of the looper  106 . The significant amount of time to rethread the looper is a result of the close proximity of the feed-dog  240  and the lifter  241  to the front portion  254  of the looper represented by distance D 1  in  FIG. 7A .  FIG. 7A  also shows prior art&#39;s looper  106  in its most retracted position, since a connecting rod  255  in the prior art comprises a continuous link. Thus, the prior art shown in  FIG. 7A  is the looper&#39;s most retracted position hereinafter referred to as Position  1 , which limits the looper to a rotation of an angle θ 1  about pin  257  on a rocker shaft  260 .  
         [0064]     To significantly reduce the amount of time required to rethread the looper  106 , the described embodiment modifies the connecting rod  255  into a two-piece linkage assembly  259 , as shown in  FIG. 7B . The two-piece linkage assembly  259  comprises a first link  256  rotatably connected to a second link  261  through connection pin  258 . The two-piece linkage assembly allows the looper  106  to rotate to an angle θ 2  about pin  257  on the rocker shaft  260 , hereinafter referred to as Position  2 . The distance between the feed-dog  240  and lifter  241  to the front of the looper  254  is represented by distance D 2  in  FIG. 7B .  
         [0065]     The new design&#39;s increase in retraction shown by distance D 2  and angle θ 2  in Position  2  is more than twice that of D 1  and θ 1  respectively. This increase in retraction resulting from the linkage assembly&#39;s design is an important advantage over the prior art, which will reduce the amount of time and effort required in rethreading the looper after thread run-outs or breaks during operation.  
         [0066]     Although the present invention has been described with a certain degree of particularity, it should be understood that those skilled in the art can make various changes to it without departing from the spirit or scope of the invention as hereinafter claimed.

Technology Category: 6