Abstract:
A tufting machine has drives for shifting needle bars, pushing needle bars, rocking loopers, knives, and hooks. The drives require less maintenance, result in less wear, are highly accurate, can operate at high speeds and at high loads, and are easily programmable. The drives avoid the need for oil bathes for the moving parts and therefore reduce spillage onto tufted products. The drives are quiet and thus are preferably over many hydraulic drives. The drives are preferably linear drives and, more preferably, are electromagnetic drives.

Description:
RELATED APPLICATIONS 
     This application claims priority to, and incorporates by reference, co-pending provisional patent application Ser. No. 60/295,745, filed Jun. 4, 2001 entitled “Magnetically Driven Tufting Machines and Methods.” 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to tufting machines and methods of tufting and, more particularly, to tufting machines and tufting involving magnetically driven elements. 
     BACKGROUND 
     A tufting machine is comprised of a number of moving parts. For instance, a tufting machine has a needle bar which goes up and down moving needles into and out of a backing material that moves along a bedrail. The bedrail itself typically moves up and down to adjust the height of the pile. In addition to moving the needles up and down, the needle bar itself can move back and forth in order to create a pattern in the produced carpet. The tufting machine also has loopers that rock back and forth catching the loops of yarn as it passes through the backing material or a combination of hooks and knives that pivot about for grabbing and then cutting the yarn to create a cut pile carpet. The movement of all of these parts and elements must be synchronized in order to produce a carpet having a desired pattern of either loop pile or cut pile. 
     Conventionally, many of these parts of a tufting machine were mechanically coupled through a set of gears and belts. These types of tufting machines had a main timing shaft that was mechanically coupled to a set of secondary shafts for controlling the loopers, knives, hooks, and needles. This type of tufting machine, however, was troublesome in that it was difficult to change the type of carpet produced, such as by changing the pattern. 
     As an example of the difficulty in making an adjustment to a tufting machine, an explanation will now be given on how adjustments are made in a needle bar drive. A common needle bar drive includes a cam having a contour that dictates the shifting of the needle bar. In operation, the cam is rotated and the needle bar is coupled to the outer edge of the cam. A lobe or cut-a-way is produced along the surface of the cam in order to shift the needle bar in one direction and then the radius of the cam is increased in order to shift the needle bar back in the opposite direction. Thus, the needle bar is shifted according to a sequence determined by the contour of this cam. 
     A difficulty with using such a cam is that in order to change the pattern, a new cam having a different contour must be placed on the tufting machine. These cams are heavy and thus are not easily replaced. For instance, some cams weigh close to 75 pounds. Additionally, the tufting machine must be placed out of commission for a period of time, such as twenty to forty-five minutes, to replace the cams. If a new cam must be produced, machining the new cam may take an hour or more before it is even ready to be placed on the tufting machine. Furthermore, these cams eventually wear out and need to be replaced. In addition to the cams, the tufting machines also have sprockets. The sprockets control the number of times the needles go up and down relative to one rotation of the cam. To change the number of times, the sprocket would have to be replaced and the new sprocket would either speed that up or slow it down depending on its size. 
     Another approach to shifting the needle bar is to use a hydraulic drive. For example, U.S. Pat. No. 4,173,192 to Schmidt et al. which is incorporated herein by reference discloses a hydraulic actuator for transversely shifting the needle bar. Tuftco of Chattanooga, Tenn., manufacturers a hydraulic tufting machine called the HydroShift. This type of tufting machine requires a hydraulic actuator, an oil bin, filters, hydraulic lines, transducers, and a pump in order to hydraulically drive the needle bar. This type of tufting machine requires a great deal of maintenance and supervision due to the use of hydraulic fluids and lines. Furthermore, the pump produces a considerable amount of noise during operation, which can be quite bothersome. 
     Other examples of tufting machines are shown and described in U.S. Pat. No. 4,759,199 to Prichard, U.S. Pat. No. 5,005,498 to Taylor et al., U.S. Pat. No. 5,526,760 to Ok, U.S. Pat. No. 5,645,001 to Green et al., U.S. Pat. No. 5,794,551 to Morrison et al., and U.S. Pat. No. 5,979,344 to Christman, Jr., which are all hereby incorporated by reference. Some of these patents describe the use of servo motors and others describe screw actuators for use in driving the elements. 
     A common problem with many of these tufting machines is that they require a considerable amount of maintenance and supervision. For instance, the screw drives and other mechanically-coupled parts wear down over time, require maintenance, and are difficult to change over to a new setting. Another common problem for many of these tufting machines, especially with the needle shifting, is that the tufting machines require oil for lubrication for these moving elements and also for cooling. For instance, servo-driven tufting machines are oil cooled while many of the needle shifting bars have oil for lubrication. Unfortunately, this oil occasionally leaks from overhead, such as from a bin for lubricating the needle shifting mechanism, and comes in contact with the backing and the carpet being produced. 
     A need therefore exists for tufting machines that require less maintenance, result in less wear to the components, offer a quicker change over, and result in less spillage of oil than existing tufting machines. 
     SUMMARY 
     The invention addresses the problems above by providing systems, tufting machines, and methods for tufting which require less maintenance, result in less wear in moving components, and also allow for a quicker change over when adjusting settings on the tufting machine. The moving components within these tufting machines do not require any bed or bath of oil to lubricate or cool the components. Furthermore, the movements can be precisely controlled to within a high degree of accuracy, at high speeds, and at controlled acceleration and deceleration. The movements may furthermore be programmed for allowing an easy and quick changeover to new settings. 
     In the preferred embodiments, the tufting machines use linear servo motors, and more preferably, magnetic drives. For instance, a shifting needle bar may be comprised of at least one rod attached to the linear motor for controlling the shifting of the needle bars. A position sensor associated with the linear drive provides position information to a processor which also generates control signals for precisely controlling the shifting of the needle bar. With such a linear drive, the needle bar can be shifted at speeds more than 800 to 1000 times a minute. This type of drive eliminates the need for any conversion between rotary to linear motion and also does not require hydraulic drives. The tufting machine with this type of shifting mechanism for the needle bar can therefore eliminate an oil bin placed above the tufting machine intended to lubricate the shifting needle bar. Consequently, the tufting machines according to the invention result in less spillage of oil onto the carpet and backing material. The tufting machines also offer a more quiet operation, which is a substantial improvement over many tufting machines, especially the hydraulically driven tufting machines. 
     In addition to the needle shifting mechanism, tufting machines according to the invention preferably include linear drives for moving the needles up and down, for lowering or raising the bed rail, for pivoting the hooks and knifes, and for rocking the loopers. A preferred tufting machine according to the invention need not have any main drive shaft as well as no associated cams, belts, and gears that are tied to the main shaft. The tufting machines according to the invention can be highly programmable with the processor controlling the various linear drives to synchronize the movements of the components. For instance, an encoder can be used to generate the timing signals for the various linear drives, with this encoder being associated with a main shaft or with the backing feed, such as on a roller. 
     The tufting machines according to the invention encompasses both entirely new tufting machines constructed with the drives according to the invention as well as tufting machines retrofitted to have one or more of the linear drives. 
     Other advantages and features of the invention will be apparent from the description below. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention and, together with the description, disclose the principles of the invention. In the drawings: 
     FIG. 1 is a partial block diagram of a tufting machine according to a preferred embodiment of the invention, including a processor and various drives and feeds; 
     FIG. 2 is a partial side view of a tufting machine having a linear drive for a needle bar according to one embodiment of the invention; 
     FIG. 3 is a schematic diagram of a locator assembly according to a preferred embodiment of the invention; 
     FIGS. 4A and 4B are partial exploded views of a linear motor according to embodiments of the invention; 
     FIG. 5 is a schematic diagram of a linear drive for a needle bar according to another embodiment of the invention; 
     FIG. 6 is an exemplary diagram of a needle push drive having a linear drive according to another embodiment of the invention; 
     FIG. 7 is an exemplary diagram of a bedrail drive having a linear drive according to another embodiment of the invention; 
     FIGS.  8 (A) and  8 (B) are exemplary diagrams of hook and knife drives having linear drives according to another embodiment of the invention; and 
     FIGS.  9 (A) and  9 (B) are exemplary diagrams of looper drives having linear drives according to another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to preferred embodiments of the invention, non-limiting examples of which are illustrated in the accompanying drawings. 
     FIG. 1 illustrates a partial diagram of a tufting machine  10 . The tufting machine  10  includes a processor  20  for controlling a number of drives  52 ,  54 ,  56 ,  58 ,  60 , and  62 . The tufting machine  10  also includes a timing unit  15  and a backing feed  30 . In this example, the tufting machine  10  has electromagnetic or linear drives for each of needle shifting drives  52 , needle pushing drives  54 , bed rail drives  56 , looper drives  58 , knife drives  60 , and hook drives  62 . The timing unit  15  may comprise any suitable timing device for allowing the processor  20  to suitably control the drives  52 ,  54 ,  56 ,  58 ,  60 , and  62  to produce a desired tufted product. For example, the timing unit  15  may comprise an encoder, a resolver, or a stepping motor which generates suitable timing signals to synchronize these various drives within the tufting machine  10 . The backing feed  30  may comprise any suitable drive mechanism for feeding the backing material through the tufting machine, such as drives including servo motors. 
     The tufting machine  10  may be used to produce any type of tufted material or product. For example, the tufting machine  10  may be used to produce loop pile carpet, cut pile carpet, rugs, as well as other products. As mentioned above, the tufting machine  10  preferably uses linear drives for each of the drives  52 ,  54 ,  56 ,  58 ,  60 , and  62 , and, more preferably, uses electromagnetic drives. One suitable provider of linear drives is California Linear Devices, Inc. of Carlsbad, Calif. The tufting machine  10 , however, may include linear drives for one or more, or even any combination of, the drives  52 ,  54 ,  56 ,  58 ,  60 , and  62 . Consequently, tufting machines according to the invention have at least one linear drive, preferably an electromagnetic drive, and any combination of servo drives, hydraulic drives, cam drives, belt drives, or other types of drives. 
     A more detailed description of the needle shifting drive  52  will now be described with reference to FIG.  2 . As shown in this figure, the tufting machine  10  includes an electromagnetic tubular linear motor  72  having an associated position sensor  74  for informing the processor  20  of the position of a needle bar  76 . The position sensor  74  can be separate from a stator of the motor  72  or, more preferably, can be integrated as a single unit with the stator. The linear motor  72  may include fans for cooling associated electronics and electro-magnets within the drive  52 . The tufting machine  10  also includes an encoder  78 , which, in this example, is coupled to a main shaft. The encoder  78  need not be coupled to a main shaft and, in fact, the tufting machine  10  need not be constructed with any main shaft. Instead, the encoder  78  may be coupled to part of the backing feed mechanism, such as on a roller. The encoder  78  serves as the timing unit  15  and provides timing signals to the processor  20  which enables the processor  20  to control the various drives  52 ,  54 ,  56 ,  58 ,  60 , and  62 . 
     The electromagnetic tubular linear motor  72  preferably has a locator assembly  80  for monitoring a position of the needle bar  76 . The linear motor  72  moves, or shifts, the needle bar  76  in a lateral movement shown by arrows A. This shifting movement of the needle bar  76  enables the tufting machine to alter the positions at which yarns are being inserted into a backing material. By shifting the needle bar  76  and by using different colored yarns, the tufting machine  10  is therefore able to form patterns in the tufted products. To control the pattern that is formed, the tufting machine  10  must have some knowledge of the location of the needle bar  76 . 
     The locator assembly  80  assists in providing the processor  20  with some knowledge of the position of the needle bar  76 . In the embodiment shown in FIG. 1, the locator assembly  80  has an adjustment point for allowing the processor  20  to position the needle bar  76  at a home position upon power-up of the tufting machine  10 . The position sensor  74  provides position data to the processor  20  which enables the processor  20  to determine an amount of distance the needle bar  76  has deviated from the home position, and thus determine the position of the needle bar  76 . The locator assembly  80  not only provides a center or home position for the needle bar  76  but preferably also provides points defining the permissible range of movement for the needle bar  76 . From this information, the processor  20  can restrict movement of the needle bar  76  to within a permissible range. 
     The locator assembly  80  is shown in more detail in FIG.  3 . An end of the needle bar  76  is connected to a shaft  82  forming part of the electromagnetic tubular linear motor  72 , whereby the motor  72  and needle bar  76  move as an integral shaft. The locator assembly  80  includes a marker  84 , which in the preferred embodiment is a protrusion  84  along part of the shaft formed by the needle bar  76  and the shaft  82  of the motor  72 . The locator assembly  80  includes a center sensor  85  for detecting the presence of the marker  84  and for sending an appropriate signal to the processor  20 . When the marker  84  is positioned at the center sensor  85 , the processor  20  determines that the needle bar  76  is at the home position. The locator assembly  80  also includes two end of range sensors  86  and  87 . As with the center sensor  85 , the end of range sensors  86  and  87  send signals to the processor  20  upon detecting the presence of the marker  84 . The processor  20  can therefore control the linear motor  72  to ensure that the needle bar  76  remains within the permissible range of movement defined by the end of range sensors  86  and  87 . 
     Thus, when the linear motor  72  moves the needle bar  76  to a position where the marker  84  is in close proximity to the sensor  85 , the tufting machine  10  determines that the needle bar  76  is in the home position. When the linear motor  72  moves the needle bar  76  to a position where the marker  84  proceeds down to its fully inserted position, the end of range sensor  86  detects the marker  84  and informs the processor  20  of such an event. Similarly, when the linear motor  72  moves the needle bar  76  so that the marker  84  is at the sensor  87 , the processor  20  determines that the needle bar  76  is at its fully retracted position. 
     The needle bar  76  is not restricted to the manner in which it is connected to needles  50  and thus may be connected in ways known to those skilled in the art. For instance, with reference to FIG. 1, the needle bar  76  is connected to drive brackets  42  and to camrol brackets  44 . These brackets  42  and  44  permit needles  50  to move in a lateral direction back and forth in the direction of arrows A in order to produce patterns in the tufted product. The needle bar  76  preferably has at least 4 inches of movement along the lateral direction, which corresponds to the distance between end of range sensors  86  and  87 , and may have a greater range of movement if desired. 
     In addition to this lateral movement, the tufting machine  10  includes the needle push drives  54  for moving the needles  50  in up and down directions, or along a vertical axis. The needle bar  76  is attached to support brackets  46  and can move up and down through the use of push rod feet  48 . A Hardin drive block has a cam auger for causing the needle bar  76  to go up and down. Needle drive push rods  45  are used in pushing the needles  50  up and down. The needle bar  76  stays in position while it is going down through a backing material so the needles  50  do not crack. When the needles  50  come back up after they clear the backing material, the needle bar  76  can shift to the next gauge or over a greater number of gauges in order to shift to a desired position. As should be apparent from the description above, the needle bar  76  can shift the needles  50  left and right and have the needles  50  go up and down simultaneously. 
     In one embodiment of the tufting machine  10 , the bed rail drives  56 , looper drives  58 , knife drives  60 , and hook drives  62  may be comprised of conventional drives. For example, shafts, such as Thompson shafts or Hardin shafts, have been used to cause balls to move in back and forth directions. A jerker guide feeds yarn down to it, with one tied down to one of the shifting shafts and letting a second needle shaft, if more than one is present, float in it. The backing feet are all stationary and do not move. The yarn passes through the needles  50  and then the hooks pick it up with the backing running under it. 
     FIG. 4A is an exploded view of the linear drive  52  used in the tufting machine  10  for shifting the needle bar  76 . The linear drive  52  includes the linear motor  72  which includes a stator  94  and a shaft  92 . The shaft  92  passes through the stator  94  and is connected to the shaft  82  of the needle bar  76 . The linear drive  52  also includes the position sensor  74  which has a probe that extends the length of the motor  72  running through the center of the stator  94 . 
     The processor  20  may detect and monitor the position of the linear motor  72  in other ways. Preferably, rather than using the sensors  85 ,  86 , and  87  and the marker  84 , the linear motor  72  has a linear encoder attached to an end of the shaft  92  as shown in FIG. 4B. A Hall-effect switch  71  detects a home position of the needle bar  76 . A read head  75  in association with a linear scale  73  provides position signals to the processor  20 . The linear encoder may comprise a scale  73 , switch  71 , and read head  75  from Renishaw PLC of Gloucestershire, United Kingdom. 
     FIG. 5 illustrates a linear drive  52 ′ for use with tufting machines according to another embodiment of the invention. The drive  52 ′ shown in FIG. 5 is an electromagnetic drive like drive  52  but differs in that linear motor  72 ′ is a flat motor whereas linear motor  72  is a tubular drive. The linear drive motor  72 ′ has a planar fixed member  102  and a second planar member  104  which is movable and attached to the needle bar shaft  82 . The linear drive motor  72 ′ is also available from California Linear Devices, Inc. 
     FIG. 6 illustrates an example of the needle push drive  54  having a linear drive according to an embodiment of the invention. The tufting machine  10  may include multiple needle push drives  54  for directly moving the needle drive push rods  45 , and hence the needles  50 , up and down. As shown in this figure, the needle drive  54  controls the up and down movement of the needles  50  into the backing material B. A bed rail  55  positions the backing material B at a desired distance relative to the needles  50 . The needle drive push rod  45  is coupled to the push rod foot  48  in a conventional manner. Alternatively, rather than having the needle push drives  54  be directly coupled to the push rods  45 , the needle push drives  54  may be positioned at ends of the tufting machine  10  and the motion of the needle push drivers  54  may be at an angle to the movement of the needles  50  up and down with some suitable coupling between the drives  54  and the needle bars, such as a rocker assembly. 
     FIG. 7 illustrates an example of the bed rail drive  56  having a linear drive according to an embodiment of the invention. The bed rail drive  56  is for controlling the height of the bed rail  55  and for placing the backing material B at the desired distance relative to the needles  50 . As is known to those skilled in the art, the height of the bed rail  55  controls the size of the loops or the length of the cut pile. Again, the tufting machine  10  may include one or more of these bed rail drives  56  for adjusting the height of the bed rail  55 . 
     FIGS.  8 (A) and  8 (B) illustrate examples of knife drives  60  and hook drives  62  having linear drives according to an embodiment of the invention. As is clear from these figures, movement of the knife drive  60  rotates a knife drive shaft  110  and thus the knives  113  associated with the shaft  110 . The hook drive  62  also controls the rotation of a hook drive shaft  112  and thus the positioning of the hooks  114 during operation of the tufting machine  10 . 
     FIGS.  9 (A) and  9 (B) illustrate an example of a looper drive  58  having a linear drive according to an embodiment of the invention. As shown in this figure, movement of the looper drive  58  controls the rotation of a looper drive shaft  116  having a set of loopers  117 . Thus, by controlling the looper drive  58 , the processor  20  can control the timing and positioning of the loopers  117  relative to the rest of the tufting operation. 
     As mentioned above, each of the drives  52 ,  54 ,  56 ,  58 ,  60 , and  62  may comprise one or more linear drives, such as one manufactured from California Linear Devices, Inc. As discussed above, the needle shifting drive  52  is coupled to the processor  20  and receives suitable control signals from the processor  20  for controlling the position of the shifting needle bar  76 . Similarly, each of the other drives  54 ,  56 ,  58 ,  60 , and  62  may receive control signals from the processor  20  for controlling the positioning, timing, and coordinating of the needles  50 , knives  113 , hooks  114 , and loopers  117 . Furthermore, the needle shifting drive  52  is associated with sensors  85 ,  86 , and  87  for providing positional information to the processor. Similarly, each of the other drives  54 ,  56 ,  58 ,  60 , and  62  may be associated with sensors for providing position feedback to the processor  20 . 
     Tufting machines having linear drives, such as linear drive  52  having motor  72  offered by California Linear Devices, Inc., have a number of advantages over conventional tufting machines. The linear devices are programmable and avoid the need for cumbersome cams and other mechanical linkage. The linear devices offer better control over acceleration and deceleration, operate at high shock loads, in rugged, harsh environments, offer a value priced solution, and are green and clean. The linear drives operate without hydraulic lines and thus avoid the considerable amount of noise and the great deal of maintenance and supervision of the hydraulic lines and fluids. The linear drives can operate at high linear speeds, with precision accuracy, for a long life, and low maintenance. The linear drives avoid the need for oil lubrication, such as from an overhead bin, and therefore avoid problems with oil leaking onto the finished product. 
     The foregoing description of the preferred embodiments of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching. 
     For example, the invention has been described with reference to the needle shifting drive  52  having the needle bar  76 . While not shown, the tufting machine  10  preferably has two shifting needle bars  76  and accordingly has two linear drives  52  for appropriately controlling each of the separate needle bars  76 . The operation and design of the tufting machine having multiple needle bars  76  is apparent from the description of the linear drive  52  and needle bar  76 . 
     The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated.