Patent Application
20060162633
The present invention relates to sewing machines and, more particularly, to sewing machines adapted to sew binding material onto carpet edges.
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.
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'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's warehouse. Also, such stationary machines tend to be costly compared to their portable counterparts.
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.
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.
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.
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.
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.
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.
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.
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.
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 '723 patent is incorporated herein in its entirety by reference. The '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.
While the carpet binding machine disclosed in the '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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Additional features will become apparent and a fuller understanding obtained by reading the following detailed description made in connection with the accompanying drawings.
A portable carpet-binding machine of the present invention is shown generally at 10 in
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.
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.
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
A detailed drawing of the single piece drive shaft 46 is shown in
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.
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
As can be seen in
In operation, as the carpet 12 is advanced by the carpet feeding assembly 200 (partially shown in
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.
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.
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.
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
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.
As can best be seen in
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
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 '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.
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
Referring more closely to
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
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 (
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
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'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.
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.
Another enhancement of the present invention is shown in
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
The new design's increase in retraction shown by distance D2 and angle θ2 in Position 2 is more than twice that of D1 and θ1 respectively. This increase in retraction resulting from the linkage assembly'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.
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.
