Abstract:
A strapping machine includes a frame, a vertically movable upper carriage, a strap chute including an upper leg mounted to the movable upper carriage, a pair of spaced apart compression plates mounted to the movable upper carriage for vertically compressing the load and a pair of side squaring elements movable toward and away from one another configured figured for horizontal movement to contact the sides of the load. The side squaring elements are disposed between the compression plates. The machine is controlled by a control system such that following a first strapping cycle and prior to a second strapping cycle the control system generates a signal to raise the compression plates from the load about 3 inches and a to move the side squaring elements away from the load about 3 inches. The machine includes a corner pad applicator assemblies for applying a corner pad at each of the upper corners of the load prior to positioning, tensioning and sealing the strapping material to itself about the load.

Description:
BACKGROUND OF THE INVENTION 
   This invention pertains to a strapping machine. More particularly, this invention pertains to a press-type strapping machine for squaring and strapping large material loads such as lumber and the like. 
   Strapping machines are well-known in the art. There are two principle types of strapping machines, manual and automatic, table-top or free-standing machines. Strapping machines are typically designed for use with either plastic or metal (steel) strapping. These machines position, tension and seal strap around a load to bundle or secure the load. 
   A typical automatic strapping machine includes a frame-like support for the overall machine, a working area to, for example, support a load, a feed head to feed strap around the load and to retract strap prior to tensioning, a chute through which the strap is fed around the load, a strapping head to secure the strap to itself and one or more dispensers for dispensing the strap material to the strapping head. 
   Many such strapping machines also provide for squaring and compressing a load during the strapping cycle. That is, an upper compression plate or platen may press downwardly on the load to provide some measure of compression (even of the load is substantially non-compressible). The machine may also include a squaring assembly to align the load vertically to prevent skewing and/or tipping. 
   In known press-type strapping machines, the strapping head is displaced from the platen and the side squaring are offset from the platen. As such, although compression and squaring occur, they do not occur at the same region of the load (not at the same longitudinal position along the load) nor in a manner such that strapping occurs at the compressed and squared location. 
   Accordingly, there is a need for a press-type strapping machine that compresses and squares a load at about the same longitudinal position along the load. Desirably, such a machine positions, tensions and seals the strap at about the compressed and squared region. More desirably, such a machine applies protecting elements at the corners of the load to prevent marring or damage of the load by the strapping material. 
   BRIEF SUMMARY OF THE INVENTION 
   A strapping machine of the type for positioning, tensioning and sealing a strapping material to itself around a load includes a frame, a vertically movable upper carriage, and a strap chute. The strap chute includes an upper leg mounted to the movable upper carriage and variable height side legs mounted to the frame and a bottom leg. 
   A pair of compression plates are mounted to the movable upper carriage for vertically compressing the load. The compression plate are spaced from one another. A pair of side squaring elements are movable toward and away from one another. The side squaring elements are configured for horizontal movement to contact the sides of the load. The side squaring elements are disposed between the compression plates. 
   A first drive vertically moves the compression plates simultaneously and a pair of second drives move the side squaring plates simultaneously and independent of one another toward and away from the load. 
   A strapping head is operably connected to the movable upper carriage. The strapping head is configured to receive a free end of the strapping material, grip the free end and form a seal of the strapping material onto itself. 
   Machine control is by a control system. The first drive actuates to move the compression plates into contact with the load to compress the load and the second drives actuate to move the side squaring elements into contact with the load to square sides of the load. The load is compressed on both sides of the squaring elements. 
   In a present embodiment, the side squaring elements include posts mounted to support members for movement toward and away from the sides of the load. The posts are mounted to the support members at a pivot to vertically align out of alignment sides of the load. Each of the pair of second drives is mounted to a respective support member at a location at a lower elevation than the pivot. 
   The strapping machine includes a corner pad applicator assembly for applying a corner pad at each upper corner of the load prior to positioning, tensioning and sealing the strapping material to itself about the load. The applicator assembly includes a reciprocating arm having a gripper for gripping the corner pad as it is conveyed to the upper corner of the load and releasing the pad when it is positioned at the upper corner of the load. The assembly is mounted pivotally to the vertically movable upper carriage. 
   A pad clamp contacts the corner pad and temporarily holds the corner pad to the upper corner of the load prior to and during positioning, tensioning and sealing the strapping material to itself about the load. A prefolding element is operably connected to the pad clamp to fold the corner pad about the upper corner prior to positioning, tensioning and sealing the strapping material to itself about the load. 
   In one embodiment, the gripper is formed from a pair of articulating jaw elements pivotally mounted to one another and to an actuator. Movement of the actuator toward and away from the jaw elements opens and closes the jaw elements. A magazine stores a plurality of corner pads. The pads are retrieved from the magazine and conveyed to the upper corner of the load by the gripper. 
   A loading sensor senses the presence or absence of the gripper at the magazine to load a corner pad into the gripper, an ejection sensor senses the presence of a pad ejected from the magazine for retrieval by the gripper and a home sensor senses the presence or absence of the corner pad applicator assembly at a home position. 
   The control system is configured such that following a first strapping cycle on the load at a first location and prior to a second strapping cycle on the load at a second location, spaced from the first location, the control system generates a signal to raise the compression plates from the load about 3 inches and a signal to move the side squaring elements away from the load about 3 inches to move the load to the second location. 
   These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The benefits and advantages of the present invention will become more readily apparent to those of ordinary skill in the relevant art after reviewing the following detailed description and accompanying drawings, wherein: 
       FIG. 1  is a front perspective view of a press-type strapping machine embodying the principles of the present invention, the strapping machine being shown with the side squaring elements in contact with the load and the upper compression plates raised from the load; 
       FIG. 2  is a partial front perspective view of the strapping machine showing the upper carriage and the strapping head; 
       FIG. 3  is a perspective view the strapping machine showing the corner pad applicator and magazine, and a corner pad being held on an upper corner of the load; 
       FIG. 4  is a view along the top of the upper carriage; 
       FIG. 5  is a front view illustration of the corner pad applicator showing a pad in each of the applicator grippers and the applicators moving toward the load to apply the pads; 
       FIG. 6  is an illustration of the applicators as the pads are applied to the load, and showing the prefolder moving downward to contact and fold the pads; 
       FIG. 7  is an illustration showing the applicator in the loading position; 
       FIG. 8  is an illustration showing the application in position to clamp and apply a corner pad; 
       FIG. 9  is an illustration showing the applicator in a crash condition, in which the applicator overshoots the load; 
       FIG. 10  is an illustration showing various parts of the applicator assembly in phantom and illustrating the carriage along which the assembly moves toward and away from the load; 
       FIG. 11  is a top view of the applicator assembly carriage; 
       FIG. 12  is a schematic illustration of the strapping machine, strap supply and control system; and 
       FIG. 13  is a cross-sectional illustration of the pad feeder and magazine. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the specific embodiment illustrated. 
   It should be further understood that the title of this section of this specification, namely, “Detailed Description Of The Invention”, relates to a requirement of the United States Patent Office, and does not imply, nor should be inferred to limit the subject matter disclosed herein. 
   Referring now to the figures and in particular to  FIG. 1  there is illustrated a press-type strapping machine  10  embodying the principles of the present invention. The term press-type is used to refer to a machine that includes a top press or platen  12  to compress the load L and side squaring elements  14  to square and compress the load L during the strapping cycle. The machine  10  includes a frame  16  on which the components are mounted. A roller table  18  is mounted to the frame  16  along which the load L is moved longitudinally through the strapper  10 . The illustrated machine  10  is shown with a load L of lumber resting on the roller table  18 . 
   The machine  10  further includes, generally a strap chute  20 , a strapping head  22 , a feed head  24  and a strap supply  26 . In the present strapper  10 , the feed head  24  and strap supply are  26  remotely located from the strapper  10  (see  FIG. 12 ). The supply  26  and feed head  24  are located at about ground elevation to facilitate maintenance and the like on the supply  26  (e.g., replacing dispenser reels  28 ) and on the feed head  24 . 
   The present strapping machine  10  includes a pair of horizontal compression plates  30   a,b  mounted to a movable upper carriage  32  which is mounted for movement on the frame  16 . The plates  30   a,b  are rigidly mounted to the carriage  32  and spaced from one another longitudinally along the load L to provide a larger area over which compression occurs. Movement of the carriage  32 , and thus compression is effected by vertical movement of the plates  30 . Movement is carried out by drives, such as the illustrated cylinders  34  (one shown) located on each side of the strapper  10  to move the carriage  32  and in turn press the plates  30  downwardly onto the load L. The cylinders  34  can be pneumatic or hydraulic cylinders, or any other drive that provides sufficient force to compress the load L. 
   Side compression or side squaring is provided by a pair of side compression columns or posts  36  that move horizontally toward and away from the sides S of the load L and contact and compress/square the load L. Each post  36  is mounted to a reinforced support  38  by a mounting pin  39  to permit a small amount of pivoting movement of the posts  36  from a vertical position. In this manner, as the posts  36  move in toward the load L, if the load L is out of square, the posts  36  will first contact that portion of the load that is out of square and, as the column  36  moves inward, it will urge the out of square load members M (e.g., individual pieces of lumber) back into square. It has also been found that minor movements of load members M are more readily effected with the pivotal post  36 , because the inward movement from and contact with both sides S of the load L will tend to move the posts  36  to a vertical orientation and thus square the load L. The side squaring elements  14  are driven by, for example, cylinders  35 . 
   In the present strapper  10 , the side compression posts  36  are positioned between the horizontal compression plates  30   a,b . It has been found that such an arrangement provides for more equally distributed forces exerted on the load L. 
   The strapping machine  10  includes a strap chute  20  through which the strap T is fed to encircle the load L and from which the strap T is pulled to bundle the load L. A portion of the strap chute  20  (the top leg  40 ) is carried on the upper carriage  32  in close proximity to the compression plates  30 , and the strapping head  22  is positioned within a portion of or opening  42  in the top leg  40 . 
   Because of the changing nature of the load L, the height of the load L can vary. Accordingly, the height of the sides  44  of the chute  20  can be varied to accommodate different load L heights. In a present strapping machine  10 , the sides  44  of the strap chute  20  are formed from a tiled arrangement, in which the wall  46  of the chute side  44  is formed from small sections  48  (thus the tile description) that pivot to open, and are biased, as by a spring (not shown), to the closed position. Diverters  50  are mounted to the upper carriage  32  (at the chute top leg  44 ) to provide a transition from each side leg  44  to the top leg  40 . The diverter  50  rides in the chute side leg  44  (between opposing tiles  48 ), and opens the tiles  48  to divert the strap T from the side leg  44  into the top leg  40  (or from the top leg  40  into the side leg  44 ). In this manner, strap T traversing through the chute  20  is maintained close to the load L. 
   The strapping head  22  is located on the upper carriage  32 , on a forward extension  52  from the front compression plate  30   a , and includes separate tensioning and sealing modules  54 ,  56 , such as those shown in U.S. patent application Ser. No. 11/852,016, filed Sep. 7, 2007 and commonly owned with the present application, and incorporated herein by reference. Unlike known tensioning arrangements, the present tensioning arrangement  54 ,  56  uses a linear or rack gear  58  to move the tensioning and sealing modules  54 ,  56  toward and away from one another. This provides for linear tensioning of the strap T (as compared to tensioning around a rotating element) which reduces curl and deformation of the strap T. 
   As set forth above, the present strapper  10  uses a remotely located strap supply  26  and feed head  24 . Strap T is conveyed to the strapping head  22  through a flexible strap guide  60  that is mounted, at one end, at about the feed head  24 , and at the other end, at about the strapping head  22 . The flexible guide  60  permits unhindered movement of the upper carriage  32  and a clear, unobstructed guide for conveying the strap T from the feed head  24  to the strapping head  22 . 
   In order to prevent marring of the load L at the upper corners U, the present strapping machine  10  includes a corner protector or pad applicator assembly  62  for applying corner protectors or pads  64  at the upper corners U of the load L at each side. The pad applicator assemblies  62  include a magazine  66  for storing corner pads  64  in a flat form, and a reciprocating arm  68  to move the pads  64  from the magazine  66  to the corner U of the load. A gripping assembly  70  is mounted to the arm  68  to grip the corner pads  64  (being ejected from the magazine  66 ) and release the pads  64  (at the load corners U). The arm  68  traverses along a rail  72  from the magazine  66  (loading position) to the application position. Rollers  74  are mounted to the arm assembly  68  to provide for moving the arm  68  along the rail  72 . 
   A pad clamp  76  is positioned on the arm assembly  68  forward of the gripping assembly  70 . The pad clamp  76  is positioned to clamp the pad  64  on the load corner U when the pad  64  is properly positioned. The clamp  76  maintains the pad  64  in place as the strap T is “pulled” around the load L and is sealed to itself to bundle the load. The assembly  62  includes a prefolding member  78  positioned between the gripping assembly  70  and the clamp  76 . The prefolding element  78  reciprocates upward, away from the pad  64 , and downward, toward (and into contact with) the pad  64 , to prefold or “break” the pad  64  at the corner U as the clamp  76  holds the pad  64  in place on the load L. This facilitates a fold F of the entire pad  64  at the corner U prior to the application of the strap T to the load L, and thus prevents skewed or torn corner protector pads  64 . 
   The gripping assembly  70  is formed by a jaw  80  having a pair of articulating jaw elements  82 ,  84 . The jaw  80  opens to release the pad  64  and swings or pivots downward (see  FIG. 6 ) and away from the load corner U to release the pad  64  and to reduce the opportunity for interfering with strapping cycle. As seen in  FIGS. 6-8  and  10 , the gripping assembly includes, in addition to the jaw elements  82 ,  84 , a support bracket  86  and an actuator arm  88 . The jaw elements  82 ,  84  are held in and pivot about the bracket  86 . The jaw elements  82 ,  84  each include a slotted drive end  90  mounted to the actuator  88  such that movement of the actuator  88  (relative to the bracket  86  and through the slotted ends  90 ) pivots the elements  82 ,  84  between the open and closed positions. 
   The magazine  66  provides a storage function (a stack K of pads  64 ) and a feed function to eject individual, singulated pads  64  from the magazine  66  and feed the individual pads  64  to the gripping assembly  70 . The pad feeder  92  includes a reciprocating plate  94  with a pusher element  96  that resides below the pad stack K and pushes or feeds individual pads  64  from the bottom of the stack K. A stop bar  98  is positioned at the side of the pad stack K to prevent multiple pads from being ejected at once. A gap  100  is defined, and properly sized, between the reciprocating plate  94  and the stop bar  98 , to permit only one pad  64  a time to be ejected. 
   The pad applicator assembly  62  includes a number of sensors. A loading sensor  102  senses the presence (location) of the assembly  62  for loading a pad  64  into the gripping assembly  70 . An ejection sensor  104  senses the presence (location) of a pad  64  ejected from the magazine  66  and ready to be gripped by the gripping assembly  70 . A home sensor  106  senses the presence (location) of the assembly  62  at the home position—this is the position in which the assembly  62  is withdrawn to the side of the strapping machine  10 . An edge sensor  108  senses the presence (location) of the edge (upper corner U) of the load L to properly position the pad  64  at the load corner U. 
   In operation, the pad applicator  62  starts with the gripping assembly  70  at the home position; in this position, the jaw  80  is closed. After the load L is squared and compressed, prior to the strap cycle commencing, a signal is received to apply a pad  64  at each of the upper corners U. The assembly  62  moves to the loading position (as sensed by the loading sensor  102 ), the jaw  80  is opened and a pad  64  is ejected form the magazine  66  into the jaw  80 . The jaw  80  then closes and the assembly  62  moves to apply the pad  64  at the corner U. The edge sensor  108  senses the edge (corner U) of the load L and the assembly  62  stops moving inward. The clamp  76  and prefolder move  78  downward such that clamp  76  contacts and holds the pad  64  on the load L, the jaw  80  opens and pivots out of the way and the prefolder  78  moves into contact with the pad  64  to fold the pad  64 . 
   The strapping cycle then commences and a strap T is positioned, tensioned and sealed around the load L with the pads  64  captured within the strap loop. The strapping machine  10  returns to the beginning of a strapping cycle (which will be appreciated by those skilled in the art) and the applicator assembly  62  returns to the home position. 
   In addition to the home, load and application positions, the applicator  62  also recognized a fault, and includes, for example, a crash position, in which, for example, the applicator overshoots the corner U of the load. In this position (an example of which is shown in  FIG. 9 ), the assembly  62  may contact the load at a non-desired location. To prevent possible damage to the load L, the assembly  62 , including the rail  72  and the gripping assembly  70  is pivotally mounted to the upper carriage  32  at a pivot location by, for example, a pivot pin  110 . In this manner, in the event there is an out of normal sequence or a fault in the operation of the strapper  10  and/or the pad applicator  62 , there is less opportunity for the applicator  62  to be damaged due to contact with the load L and less opportunity for the load L to be damaged due to contact from the pad applicator  62 . 
   A control system  112  controls the operation of the strapper  10 . The system  112  includes a microprocessor or like programmable, configurable controller  114  for sensing the state and status of the machine  10  and to generate signals, accordingly, to control the machine  10  functions (e.g., cylinder  34 ,  35  operation, strapping head  22  operation and the like). Those skilled in the are will appreciate the design and operation of the control system  112 . The present control system  112  uses a touch screen  116  that displays the various controls and functions of the machine  10  and that “hides” controls for operations that are not “allowed” or are locked-out at times during machine  10  cycle operation. 
   As set forth above, the present press-type strapping machine  10  is configured to apply (position, tension and seal) strap T at multiple locations on a single load L. That is, straps T can be placed at a number of locations on, for example, a single a load of lumber. To effect efficient operation, between the application of the several straps T, the compression members  30 ,  36  of the present machine  10  will move only far enough to allow for longitudinal movement of the load L in the machine  10 . In prior machines, once a strap had been positioned around the load at one location, the entire strapping system would reset to a home position, which requires fully retracting the side squaring and compression plates, moving the load (generally only a few feet along the roller base) and then commencing the full strapping cycle once again to position a strap at a different location along the load. 
   The present machine  10  senses the outer bounds or envelope of the load L and moves the upper carriage  32  and side squaring posts  36  away from the load L only about 2 to 3 inches to allow for longitudinally moving the load L to the next strap T location. This small movement (as compared to full resetting the machine) has been found to save considerable time and result in considerable cost savings, in the strapping process. 
   All patents referred to herein, are incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
   In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
   From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present invention. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover by the appended claims all such modifications as fall within the scope of the claims.