Abstract:
A clamping system for a sewing machine used to sew first and second materials together. The clamping system has a plurality of clamps mounted adjacent an opening in a frame. Each of the clamps has a stationary member, a movable member and an actuator. The actuator is connected to the movable member and operates to move the movable member in a clamping relationship with the stationary member to clamp the first material in the clamp. The clamp is powered by a cylinder with a linear stroke, and the clamp has a driving member that transfers the linear motion of the cylinder into a pivoting motion of the movable member. Further, the movable and fixed members have forward ends shaped so that they hold the first material but do not interfere with a sewing of the first member to the second member.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to sewing machines and more particularly, to a method and apparatus for holding a mattress label while it is being sewn to a mattress panel.  
         BACKGROUND OF THE INVENTION  
         [0002]    Manufacturers are particularly concerned that high quality products portray a high quality image. To this end, identifying labels are preferably made of a high quality material and attached to the product in a high quality manner. In the mattress field, mattress companies have specifications regarding the appearance and the attachment of the label. Among these is the requirement that the outer edge of the label must be securely sewn to a top panel of the mattress. In addition, the label should not have trim tails or other unsightly features.  
           [0003]    Label sewing machines are known. One such machine is disclosed in U.S. Pat. No. 5,520,129 entitled “Method and Apparatus for Join and Sew Application”. With such a machine a mattress label is placed in a frame and held therein by pins or tacks located at each corner of the frame. While the tacks function well to hold the label, it requires mental focus and manual dexterity to manipulate each small corner of the label such that it is properly secured to a respective tack. When performed repeatedly over periods of time, such an operation can be stressful and prone to error. In addition, a corner of the label may accidently come off of its respective tack. Whether from an improper loading of the label or an accidental release of a label corner, a loose label corner often results in the label not being properly sewn on the mattress. Manually removing and/or resewing the label on the mattress panel is labor intensive and expensive.  
           [0004]    Therefore, there is a need for a better way to more reliably secure the mattress label while it is being sewn on a mattress panel.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides a clamping system for a sewing machine that reliably secures the mattress label while it is being sewn on a mattress panel. The clamping system of the present invention is easier to use and therefore, leads to a faster and more reliable placement of the mattress label in the sewing machine. Thus, the clamping system of the present invention is especially useful in a production environment where its ease of use and reliability help to substantially relieve sewing machine operator stress in the process of sewing a label to a product. Further, the clamping system of the present invention substantially reduces rework or resewing of a label and therefore, provides a more efficient and cost effective label sewing operation.  
           [0006]    According to the principles of the present invention and in accordance with the described embodiments, the invention provides a clamping system for a sewing machine. The sewing machine has a frame and an opening in the frame for receiving a first material that is to be sewn with the sewing machine to a second material. The clamping system has a plurality of clamps mounted adjacent the opening in the frame. Each of the clamps has a stationary member, a movable member and an actuator. The actuator is connected to the movable member and operates to move the movable member in a clamping relationship with the stationary member to clamp the first material in the clamp.  
           [0007]    In one aspect of the invention, the clamp is powered by a cylinder with a linear stroke, the clamp has a driving member that transfers the linear motion of the cylinder into a pivoting motion of the movable member. Further, the movable and fixed members have forward ends shaped so that they hold the first material but do not interfere with a sewing of the first material to the second material.  
           [0008]    In another embodiment of the invention, a method of securing a stitchable material in a sewing machine having a frame and an opening in the frame for receiving the stitchable material. First, an edge of the stitchable material is located between a movable member and a fixed member of a clamp mounted adjacent the opening. Next, the movable member is moved toward the stationary member to clamp the edge of the stitchable material between the movable and the stationary members. In one aspect of this invention, a driving member is translated by an actuator and raises a rearward end of the movable member, thereby pivoting a forward end of the movable member against a forward end of the stationary member.  
           [0009]    These and other objects and advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic perspective view of a mattress label sewing system utilizing a clamping system in accordance with the principles of the present invention.  
         [0011]    [0011]FIG. 2 is top plan view of one of the clamps of the clamping system illustrated in FIG. 1.  
         [0012]    [0012]FIG. 3 is side view in partial cross-section of the clamp of FIG. 2 illustrating the clamp in an open position.  
         [0013]    [0013]FIG. 4 is side view in partial cross-section of the clamp of FIG. 2 illustrating the clamp in a closed position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    Referring to FIG. 1, a sewing system  20  includes a frame  22  mounted on a base plate  24 . The base plate  24  and a pivotable panel clamp  28  are movable in mutually perpendicular X and Y directions with respect to a base  27  in a known manner. A sewing machine  30  has a needle  34 , a presser foot  36 , a bobbin (not shown) and actuators (not shown) for moving the base plate  24  and panel clamp  28  in response to command signals from a sewing machine controller  38  in a known manner.  
         [0015]    The sewing machine  30  is an electronically programmable X-Y sewing machine that, in one embodiment, utilizes a Mitsubishi No. PLK A 4516 sewing machine. The sewing machine  30  performs lock-stitching and may be programmed to implement different styles of lock-stitching, for example, a zigzag stitch of 7.5 millimeters. Lock-stitching is a known technique of interlacing a needle thread and bobbin thread, which will not be described here further except to indicate that a needle thread is carried by needle  34  and a bobbin thread provided by a bobbin (not shown).  
         [0016]    The operation of the sewing machine  30  is controlled by user operating I/O devices  37  on a front panel of the controller  38 . During execution of a control program, the controller  38  receives inputs from devices, for example, a main shaft encoder, and provides command signals to a sewing head motor (not shown) and actuators (not shown) to implement a stitch pattern in a known manner. The controller  38  also provides command signals to perform other operations, for example, raise and lower the presserfoot  36 , raise and lower the panel clamp  28 , etc. In those operations, the command signals are received by solenoids (not shown) that, in turn, change the states of pneumatic logic, which supply pressurized air to various pneumatic components in a known manner. The air cylinders and other pneumatic devices are commercially available from various suppliers, for example, Bimba Manufacturing Company of Monee, Ill. The structure and operation of a sewing machine similar to the sewing machine described herein is fully described in U.S. Pat. No. 5,520,129 entitled “Method and Apparatus for Join and Sew Application”, which application is hereby incorporated by reference in its entirety herein.  
         [0017]    The sewing machine  30  is illustrated with the panel clamp  28  in its raised position. The label frame  22  and base plate  24  have respective openings  40  in which a mattress label  42  can be located. A label clamping system  44  is used to hold the mattress label  42  within the opening  40 . The label clamping system  44  is comprised of four clamps  46  mounted on the label frame  22 . Each of the clamps is identical in its structure and operation.  
         [0018]    Referring to FIG. 2, a clamp  46  has an actuator  50 , for example, a pneumatic cylinder, mounted to an upper side of the frame  22  by fasteners  48  or other means. The actuator  50  has an actuator shaft or rod  52 , for example, a cylinder rod, extending from a forward end. The actuator rod  52  extends and retracts or translates through a linear motion in response to the actuator  50  being operated between its two states. The actuator rod  52  is connected to a rearward end of a toggle driver  54  by a pin or other fastener  56 . The toggle driver  54  has a slot  58  that receives a guide pin  60 , for example, a screw or other fastener. The slot  58  and guide pin  60  function with the actuator rod  52  to facilitate a translation or linear motion of the toggle driver  54 .  
         [0019]    A movable pivot clip or member  64  is pivotally mounted on the frame  22  with a pivot pin  66  that is located in a groove  68  and secured by pin clamps  70 . As shown in FIG. 3, the pivot clip  64  is mounted in a slot  72  located in an upper surface of the frame  22 . A fixed or stationary clip  74  is mounted by fasteners (not shown) in a slot  76  located in a lower surface of the label frame  22 . The forward end  78  of the movable clip  64  and the forward end  80  of the fixed clip  74  extend over an opening edge  81  and into the opening  40  in the label frame  22 . The forward ends  78 ,  80  of the respective clips  64 ,  74  have a shape that is effective to secure the label  42  therebetween but does not interfere with the sewing machine sewing around a perimeter of the label  42 . As shown in FIG. 2, the forward ends  78 ,  80  of each of the respective clips  64 ,  74  terminate with a pair of small pointed tips  82  that are separated by a V-shaped cutout  84 .  
         [0020]    Referring to FIG. 3, the forward end of the toggle driver  54  has an angled or inclined surface  62  that receives a rearward end  86  of the pivot clip  64 . When the actuator  50  is in a first state in which the actuator rod  52  is fully retracted, the rearward end  86  of the pivot clip  64  is located at a lower end of the inclined surface  62 , thereby placing the forward end  78  of the pivot clip  64  in a raised position. A user generated command signal from the controller  38  changes a state of an actuator solenoid (not shown) that, in turn, changes a flow of pressurized air to the actuator  50 , thereby changing its state. Changing the state of the actuator  50  extends the actuator rod  52  and moves the toggle driver  54  forward, that is, from left to right as viewed in FIG. 3. As the inclined surface  62  is moved forward, the rearward end  86  of the pivot clip  64  moves up the inclined surface  62 , thereby pivoting the pivot clip  64  clockwise as viewed in FIG. 3 about the pivot pin  66 . Raising the rearward end  86  of the pivot clip  64  simultaneously lowers its forward end  78 . Referring to FIG. 4, when the actuator rod  52  is fully extended, the pivot clip forward end  78  is closed against the forward end  80  of the stationary clip  74 , thereby closing the clamp  46  and securing the label  42  therein.  
         [0021]    When the command signal from the controller  38  again changes state, it changes the state of the actuator solenoid that, in turn, changes a flow of pressurized air to return the actuator  50  to its original state. In that process, actuator rod  52  is retracted; and the toggle driver  54  moves rearward, that is, from right to left as viewed in FIG. 4. As will subsequently be described, the pivot clip  64  is pivoted counterclockwise as viewed in FIG. 3 and its rearward end  86  moves down the inclined surface  62 . The lowering of the rearward end  86  of the pivot clip  64  simultaneously raises its forward end  78 , thereby opening the clamp  46  as shown in FIG. 3. The pivot clip rearward end  86  is made to be heavier than the forward end  78 , and therefore, the pivot clip rearward end  86  tends to drop down.  
         [0022]    In use, referring to FIG. 1, a user operates appropriate I/O devices  37  on the controller  38  to move the base plate  24  to a desired starting location and then to raise panel clamp  28  in a known manner. Thereafter, the user disposes a label  42  face-side down in the opening  40  and locates edges of the label  42  on the forward ends  80  (FIG. 3) of respective stationary clips  74 . When the label edges are located on the stationary clips  74  to the user&#39;s satisfaction, the user operates appropriate I/O devices  37  on the controller  38  to command a change of state of all of the actuators  50  (FIG. 3) of all respective clamps  46 . The actuators  50  simultaneously extend respective actuator rods  52  and move respective toggle drivers  54  forward. The forward motion of the respective toggle drivers  54  lowers respective pivot clip forward ends  78  against respective stationary clip forward ends  80 . That process simultaneously closes all of the clamps  46  and clamps edges of the label  42  between the pivot clip forward ends  78  and respective stationary clip forward ends  80 . As will be appreciated, after the clamps  46  have been closed, the user can operate appropriate I/O devices  37  on the controller  38  to command the clamps  46  to open, so that edges of the label  42  can be repositioned. The clamps  46  are then closed again as described above.  
         [0023]    After the label  42  is properly positioned within the opening  40 , the user then places a mattress panel (not shown) over the clamped label  42 . The user again activates appropriate I/O devices  37  on the controller  38  to lower the panel clamp  28 . The panel clamp  28  secures the mattress panel against the frame  22  in a desired position relative to the clamped label  42  in a known manner. The user then operates the sewing machine  30  so that the label is sewn to the mattress panel with a lock-stitch along an edge of the label. The pointed profiles of the forward ends  78 ,  80  of the respective pivot and stationary clips  64 ,  74  permit the label edge to be satisfactorily secured and also allow a zig-zag stitch or the like to proceed down a label edge without interference from the clamps  46 .  
         [0024]    After the sewing operation is complete, the user again operates appropriate I/O devices  37  on the controller  38  to raise the panel clamp  28 . Next, the user operates appropriate I/O devices  37  to command a change of state of all of the actuators  50  (FIG. 3) of the respective clamps  46 . The actuators  50  simultaneously retract respective actuator rods  52  and move respective toggle drivers  54  rearward. However, after the sewing operation, the mattress panel is resting on top of the forward ends  78  of the pivot clips  64 ; and therefore, the rearward ends  86  remain elevated after the respective toggle drivers  54  have been retracted. The user then lifts the mattress panel and sewn label off of the sewing apparatus  20 . The mattress label  42  is between the pivot clips  64  and respective stationary clips  74 ; and as the mattress label  42  is raised from the frame  22 , it raises the forward ends  78  of respective pivot clips  64 . Thus, the rearward ends  86  of the respective pivot clips  64  drop down onto lower ends of respective inclined surfaces  62 , and all of the clamps  46  are open ready to receive another mattress label.  
         [0025]    The above-described clamping system  44  reliably secures a label while it is being sewn to a mattress panel. The clamping system  44  is easy to use and therefore, leads to a faster and more reliable placement of the mattress label in the label frame  22  of the sewing machine  30 . Thus, the clamping system  44  is especially useful in a production environment where its ease of use and reliability help to substantially relieve sewing machine operator stress in the process of sewing a label  42  to a product. Further, the clamping system  44  substantially reduces rework or resewing of a label and therefore, provides a more efficient and cost effective label sewing operation.  
         [0026]    While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, in the described embodiment of FIG. 2, four clamps  46  are mounted as two opposed pairs of clamps on opposite lateral sides of the frame  22 . As will be appreciated, in other embodiments, the clamps  46  may be arranged in other configurations around the perimeter of the frame  22 , for example, one clamp can be mounted on each of the four sides of the frame  22  or the two pairs of clamps may be mounted on opposed upper and lower sides of the frame  22 .  
         [0027]    In the described embodiment, the sewing system  20  is used to sew a label onto a mattress panel; however, as will be appreciated, the sewing system  20  can be used to sew other stitchable materials, for example, leather, a “KEVLAR” composite material, etc. Therefore, in other embodiments, the number of clamps  46  used can be changed to meet the needs of a particular application, for example, depending on the stiffness of the materials being sewn, a greater number or a fewer number of clamps  46  may be used. Further, in the described embodiment, the clamp actuator  50  is described as being pneumatically operated; however as will be appreciated, in other embodiments, the clamp actuator  50  may be electrically operated.  
         [0028]    In the described embodiment, the pivot clip  64  is opened by the act of the sewn mattress panel and label being removed from the sewing system  20 . However, as will be appreciated, in alternative embodiments, a positive opening force can also be applied to the pivot member  64 , for example, a torsion spring can be mounted over the pivot pin  66  and used to apply a biasing force to help move the pivot clip rearward end  86  down the inclined surface  62 . In still other embodiments the toggle driver  54  can be replaced by other mechanisms for operatively connecting the actuator  46  to the pivot clip  64 .  
         [0029]    Therefore, the invention in its broadest aspects is not limited to the specific details shown and described. Consequently, departures may be made from the details described herein without departing from the spirit and scope of the claims which follow.