Abstract:
A pallet assembly device is disclosed that is configured to automatically position pallet components together and to automatically secure such components to each other. Furthermore, the pallet assembly device of the invention is preferably fed stacks of pallet components, and thereby eliminates the need for an assembly operator to manually position various pallet components in a jig or carriage. Yet further, the device preferably comprises a plurality of wheels that are positioned to simultaneously engage opposite sides of a pallet component and comprises a drive motor. The drive motor is preferably operatively connected to at least one of the plurality of wheels in a manner allowing the drive motor to rotationally drive and rotationally stop at least one of the plurality of wheels so as to move the component along an assembly path. A method of assembling pallet components using a pallet assembly device is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates generally to the field of pallet assembly devices and methods of assembling pallets. More particularly, the invention pertains to an automated pallet assembly apparatus for producing block-style pallets that is configured to automatically attach three blocks to an individual slat in a manner to form a stringer of a block-style pallet. The apparatus is configured to automatically repeat the procedure utilizing blocks and slats automatically retrieved from stacks of blocks and slats held in dispensing stations of the apparatus. The assembly apparatus provides an economical method for rapidly fabricating block-style pallet stringers. 
     (2) Related Art 
     Numerous automated devices have been developed to facilitate the assembly of pallets. These devices include relatively inexpensive devices that perform only small sub-portion of pallet assembly and also include large scale pallet assembly devices that are capable of automatically producing several hundred pallets per hour. 
     Despite the many developments made in industry for assembling pallets, the are many disadvantages associated with various types of prior art automated pallet assembly devices. One obvious such disadvantage is the cost of such assembly devices, which can make large automated assembly devices uneconomical for production facilities that do not have the demand for operating such devices continually. Other less complex and less expensive assembly devices require slats, stringers, blocks, or other pallet components to be manually positioned in their relative assembled positions or within jigs or carriages. Such manual positioning tends to increase labor costs and/or slow production rates. At least some relatively small scale assembly devices, such as the device disclosed in U.S. Pat. No. 4,403,388, automatically position at least some pallet components in their assembled position prior to assembling such components. However, such devices, despite being relatively small in scale, often have numerous moving parts that are subject to wearing and/or require frequent maintenance. 
     SUMMARY OF THE INVENTION 
     It is in view of the above problems that the present invention was developed. The present invention overcomes many of the disadvantages associated with prior art pallet assembly devices by providing a pallet assembly device for, and method of, automatically positioning various pallet components, as well as automatically attaching such components together, without requiring numerous moving parts. 
     One aspect of the invention generally pertains to pallet assembly device that preferably comprises a slat dispensing station, a block dispensing station, a clamping station, a slat conveying mechanism, a block conveying mechanism, and an automatic fastening device. The slat dispensing station is configured and adapted to hold a plurality of pallet slats stacked vertically one above another. Likewise, the block dispensing station is configured and adapted to hold a plurality of pallet blocks stacked vertically one above another. The clamping station is configured and adapted to bias a block into engagement with a slat. The slat conveying mechanism operatively connects the slat dispensing station to the clamping station and is configured and adapted to repetitively engage and separate a lower most slat from a plurality of slats positioned in the slat dispensing station and to transfer such a slat to the clamping station. The slat conveying mechanism is further configured and adapted to position that slat at first, second, and third distinct stopped positions relative to the clamping station. The block conveying mechanism is configured and adapted to repetitively engage and separate a lower most block from a plurality of blocks positioned in the block dispensing station and to transfer that block to the clamping station. The block conveying mechanism is further configured and adapted to position blocks above the slat when the slat is stopped in any one of the first, second, and third distinct stopped positions. The automatic fastening device is configured and adapted to force a fastener upwardly through the slat and into a block when the slat and has been stopped in any one of the first, second, and third positions and such a block is being bias into engagement with the slat. 
     Another aspect of the invention generally pertains to pallet assembly device that preferably comprises a component dispensing station, a clamping station, and a component conveying mechanism. The component dispensing station is configured and adapted to hold a plurality of pallet components and the clamping station is configured and adapted to bias pallet components together. The component conveying mechanism operatively connects the component dispensing station to the clamping station and comprises a plurality of wheels that are mounted to the assembly device for rotation about separate axes. The wheels are positioned to simultaneously engage opposite sides of a pallet component when such a component is being transferred by the component conveying mechanism to the clamping station. The component conveying mechanism also comprises a drive motor that is operatively connected to at least one of the plurality of wheels in a manner allowing the drive motor to rotationally drive and rotationally stop at least one of the plurality of wheels to thereby adjust the position of a pallet component relative to the clamping station. 
     Yet another aspect of the invention pertains to a method of assembling a pallet that preferably comprises the step of providing an automated pallet assembly apparatus having an assembly path, a slat dispensing station, and a block dispensing station, with the assembly path operatively connecting the slat dispensing station to the block dispensing station. The method further preferably comprises providing a plurality of slats to the slat dispensing station and providing a plurality of blocks to the block dispensing station. 
     The method also preferably comprises utilizing the assembly apparatus to automatically move a first one of the plurality of slats longitudinally along the assembly path from the slat dispensing station toward the block dispensing station and to automatically stop the movement of the first slat at a first position along the assembly path. In the first position, a first longitudinal end of the first slat is positioned adjacent the block dispensing station along the assembly path. The method yet further preferably comprises automatically biasing a first block of the plurality of blocks into engagement with the first slat, when it is stopped in the first position, and automatically fastening the first slat to the first block while the first slat and the first block are being biased into engagement with each other. 
     Still further, the method preferably comprises utilizing the assembly apparatus to automatically longitudinally move the first slat from the first position and to automatically stop the movement of the first slat at a second position along the assembly path. The second position is further along the assembly path from the slat dispensing station than the first position and the method preferably further comprises automatically biasing a second block into engagement with the first slat, when it is in the second position, and automatically fastening the first slat to the second block while the first slat and the second block are being biased into engagement with each other. 
     Yet further, the method preferably comprises utilizing the assembly apparatus to automatically longitudinally move the first slat from the second position and to automatically stop the movement of the first slat at a third position along the assembly path. In the third position, the longitudinal end of the slat opposite its first longitudinal end is positioned adjacent the block dispensing station along the assembly path. Finally, the method yet further preferably comprises automatically biasing a third block into engagement with the first slat, when it is in the third position, and automatically fastening the first slat to the third block while the first slat and the third block are being biased into engagement with each other. 
     Further features and advantages of the present invention, as well as the structure and operation of an embodiment of the present invention, are described in detail below with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the preferred embodiment of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
     FIG. 1 is an isometric view of a standard block-style pallet; 
     FIG. 2 illustrates an isometric view of the preferred embodiment of a pallet assembly device in accordance with the invention; 
     FIG. 3 illustrates a partial detail view of the slat dispensing station and a portion of the slat conveying mechanism of the pallet assembly device of FIG. 2, shown with portions thereof removed for clarity; 
     FIG. 4 illustrates a partial detail view of the pallet assembly device of FIG. 2, focusing on the clamping station and the block dispensing station with portions of the block dispensing station removed for clarity; 
     FIG. 5 illustrates a partial detail view of the block dispensing station of the pallet assembly device of FIG. 2, shown with portions thereof removed for clarity; 
     FIG. 6 illustrates a view of the drive wheels assembly of the pallet assembly device of FIG. 2, shown with the block dispensing station removed therefrom for clarity; 
     FIG. 7 is a view similar to FIG. 2, showing a slat in a first position with a block clamped thereto; 
     FIG. 8 is a view similar to FIG. 2, showing the slat of FIG. 7 in a second position with the first block attached thereto and with a second block clamped thereto; and 
     FIG. 9 is a view similar to FIG. 2, showing the slat of FIGS. 7 and 8 in a third position with the first and second blocks attached thereto and with a third block clamped thereto. 
    
    
     Reference characters in the written description of the specification indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The pallet assembly device of the preferred embodiment of the invention is specifically configured and adapted to assemble portions of a standard block-style pallet  20  of the type shown in FIG.  1 . In particular, the pallet assembly device of the preferred embodiment is configured and adapted to assemble the stingers  22  of block-style pallets  20 , which themselves each comprise a single slat  24  with a block  26  attached at each longitudinal end thereof and another block positioned centrally therebetween. 
     In general, the pallet assembly device  28  of the preferred embodiment is shown in FIGS. 2-9 and comprises a slat dispensing station  30 , a block dispensing station  32 , and a clamping station  34 . The pallet assembly device  28  further includes a slat conveying mechanism  36  and a block conveying mechanism  37 . The slat conveying mechanism  36  is configured to move slats longitudinally from the slat dispensing station  30  through the clamping station  34 , thereby defining an assembly path along which such slats travel. The block conveying mechanism  37  is configured to move blocks from the block dispensing station  32  to the clamping station  34 . 
     The slat dispensing station  30  of the pallet assembly device  28  of the preferred embodiment generally comprises a receiving bin  38  that is formed of a plurality of opposed vertical side wall members  40  that are mounted to a horizontal surface  42 . The side wall members  40  are spaced apart from each other such that a slot  44  is formed that has a width slightly larger than the width of the slats  24  being used to form the stingers  22  of the block-style pallets  20 . A vertical end wall  46  is preferably mounted to a pair of the side wall members  40  in a manner such that it substantially closes the slot  44  at one end. However, the end wall  46  is mounted to the side wall members  40  in a manner such that it is spaced above the horizontal surface  42  by a distance greater than the thickness of each of the slats  24  but less than twice such thickness. The opposite ends  50  of the side wall members  40  remain open and are preferably flared apart. The pair of side wall members  40  and the end wall  46  are preferably secured to each other and to the horizontal surface  42  using bolts passed through slotted holes so as to allow the width of the slot  44  and the height of the opening  48  to be adjusted to accommodate various alternative sizes of slats  24 . A roll pin  52  is preferably mounted to the horizontal surface  42  adjacent the open end of the slot  44 . Finally, an elongated slot  54  extends through the horizontal surface  42  along the length of the slot  44  of the receiving bin  38  to accommodate a portion of the slat conveying mechanism  36  of the pallet assembly device  28 , as described below. 
     The block dispensing station  32  of the pallet assembly device  28  of the preferred embodiment comprises a block holder member  56  that extends vertically from a horizontal block holder surface  58 . The block holder member  56  preferably comprises a plurality of bar members  60  that are spaced from each other to form a slot  62  that is dimensioned to receive and hold a plurality of stacked blocks  26  of the type used to form the block-style pallets  20 . Adjustment knobs  61  are provided to allow the space between the bar members  60  to be adjusted to accommodate different sizes of blocks  26 . The bar members  56  are spaced above from the horizontal block holder surface  58  by a distance larger than the height of a block  26 , but less than the height of two blocks, in a manner such that an opening  64  is formed at the base of the block holder. The opening allows a lower most block  26  resting on the horizontal block holder surface  58  to pass horizontally out of the slot  62  of block holder  56  via the block conveying mechanism  37  as is described below. 
     The clamping station  34  of the pallet assembly device  28  of the preferred embodiment comprises a fluid cylinder  66  supporting an upper horizontal plate  68  that opposes a lower base plate  70  therebeneath. A vertically oriented side plate  72  is positioned adjacent one side of the upper horizontal plate  68  and extends between the upper horizontal plate and the lower base plate  70 . The clamping station  34  further comprises an automatic fastening device (not shown) positioned beneath the lower base plate  70 . A fastener slot  74  extends through the base plate  70  and is aligned with the automatic fastening device. The fluid cylinder  66  is configured to raise and lower the upper horizontal plate  68  relative to the lower base plate  70 . The automatic fastening device is preferably mechanical stapler of the type that cuts and forms staples from an arbitrary length of wire, such as from a spool of wire. The automatic fastening device is configured and adapted to drive such staples upwardly through the fastener slot  74  of the lower base plate  70 . 
     The slat conveying mechanism  36  of the pallet assembly device  28  of the preferred embodiment includes portions of the slat dispensing station  30  and the clamping station  34 . In particular, the horizontal surface  42  of the slat dispensing station  30  and the lower base plate  70  and side plate  72  of the clamping station  34  act as bearing surfaces along which slats  24  travel when being conveyed by the slat conveying mechanism  36 . The slat conveying mechanism  36  also comprises, among other things, a cylinder  76 , two parallel rows of guide wheels  78 , and a slat position sensor  80 . As seen in FIG. 3, the cylinder  76  of the slat conveying mechanism  36  is positioned beneath the horizontal surface  42  of the slat dispensing station  30 . The cylinder  76  is connected to a tooth member  82  that extends upwardly through the elongated slot  54  of the horizontal surface  42  and slightly into the slot  44  of the receiving bin  38  and is configured to selectively move the tooth member back and forth horizontally along the elongated slot. One or more sensors  84  may also be provided to identify when the tooth member reaches limit positions relative to the elongated slot  54 , so as to prevent damage to the components of the pallet assembly device  28  and to reverse the direction of the cylinder&#39;s  76  operation. 
     The wheels  78  of the slat conveying mechanism  36  form a row of idler wheels  86  and a row of drive wheels  88 . The row of idler wheels  86  is parallel to the row of drive wheels  88  and the rows are positioned horizontally spaced apart from each other immediately above the lower base plate  70  of the clamping station  34 , on opposite sides of the fastener slot  74 . The idler wheels  86  are each suspended from a first beam  90  and are configured to freely rotate about separate vertical axes. The drive wheels  88  are mounted above a second beam  92  and a configured to rotate with separate vertical axles that are link together to rotate in unison via a plurality of drive belts  96 . The drive belts  96  are linked to a electric motor  98 . The slat position sensor  80  is positioned between the idler wheels  86  and the drive wheels  88  immediately above the lower base plate  70  of the clamping station  34  where it will detect a slat  24  passing over the lower base plate. 
     The block conveying mechanism  37  of the pallet assembly device  28  of the preferred embodiment comprises another cylinder  100  and a plurality of sensors  102 . Like the other cylinders, the cylinder  100  of the block conveying mechanism is preferably pneumatic. The piston is connected to the block dispensing station  32  and is configured and adapted to move a pushing ram  104  horizontally back and forth over the block holder surface  58 . As the pushing ram  104  moves in response to the piston  100 , the pushing ram  104  passes back and forth beneath the bar members  60  of the block holder through the opening  64  at the base thereof. The sensors  102  are mounted where they can identify the position of the pushing ram  104 , so as to limit the travel of the cylinder  100 , thereby preventing damage to the pallet assembly device  28  by stopping or reversing the direction of the cylinder&#39;s operation. 
     In addition to the components discussed above, the pallet assembly device  28  also comprises various other elements such as a base frame  106  formed of welded square tubing and an electronic control unit (not shown) for controlling the operation of the various above-mentioned components. The base frame  106  supports and physically connects the various stations of the pallet assembly device  28  and comprises several adjustment clamps  108 . The base frame  106  generally holds the slat dispensing station  30  in a fixed orientation relative to the clamping station  34  and in a manner such that the horizontal surface  42  of the slat dispensing station is coplanar with the lower base plate  70  of the clamping station. The side plate  72  of the clamping station  34  is supported by the first beam  90  of the slat conveying mechanism  36 , which is mounted to the base frame  106  in a manner such that the first beam, along with the side plate and the idler wheels  86  of the slat conveying mechanism, can be horizontally repositioned relative to the lower base plate  70  of the clamping station. At least one of the clamps  108  of the base frame  106  is configured to lock the first beam  90  of the slat conveying mechanism  36  in a given position. The block dispensing station  32 , the block conveying mechanism  37 , and the second beam  92 , drive wheels  88 , drive belts  96 , and electric motor  98  of the slat conveying mechanism  36  are all preferably fixed in position relative to each other as a unit but are also horizontally adjustable relative to the base frame  106 . A hand operated crank  110  facilitates such adjustments and the unit can be locked in a particular position via use of the adjustment clamps  108 . 
     The electronic control unit of the pallet assembly device  28  is operatively connected to the slat conveying mechanism  36 , the block conveying mechanism  37 , and the clamping station  34 . The control unit is configured to activate the various cylinders  66 , 76 , 100 , the electric motor  98 , and the automatic fastening device in response to signals from the slat position sensor  80 . 
     Prior to operation, the pallet assembly device  28  of the preferred embodiment can first be adjusted to accommodate the specific dimensions of the slats  24  and blocks  26  being used to form the stringers  22  of the particular block-style pallet  20  being assembled. This is done by adjusting the side wall members  40  and the end wall  46  of the receiving bin  38  of the slat dispensing station  30  such that the slats  24  will fit loosely in the slot  44  of the receiving bin with little excess play. By loosening the adjustment clamps  108  of the base frame  106 , the distance between first and second beams  90 , 92  of the slat conveying mechanism  36  is adjusted such that a slat  24  can pass between the drive wheels  88  and the idler wheels  86  with a slight press fit to ensure that the wheels will be in frictional engagement with the slats. Allowing both the first and second beams  90 , 92  of the slat conveying mechanism  36  to be adjusted, allows the fastener slot  74  in the lower base plate  70  of the clamping station  34  to remain positioned centrally between the drive wheels  88  and the idler wheels  86 , as is desirable. Once in place, the adjustment clamps  108  are tightened to secure the first and second beams  90 , 92  in place. The bar members  60  of the block holder member  56  of the block dispensing station  32  can also be adjusted if needed via the adjustment knobs  61  such that blocks  26  of a particular size will fit loosely in the slot  44  of the block holder member  56  with little excess play. 
     In operation, a plurality of slats  24  are either manually or automatically loaded into the receiving bin  38  of the block dispensing station  32  in a stacked manner. The roller pin  52  of the block dispensing station  32  can assist a person in inserting the first few slats  24  longitudinally into the receiving bin  38 . In a similar manner a plurality of blocks  26  are either manually or automatically loaded into the slot  62  of the block holder member  56  of the block dispensing station  32 . 
     When activated, the control unit of the pallet assembly device  28  of the preferred embodiment begins the process of automatically assembling a stinger  22  by activating the cylinder  76  of the block conveyor mechanism  37 . When activated, the piston  76  retracts and causes the tooth member  82  to move along the elongated slot  54  of the horizontal surface  42  in a direction toward the clamping station  34 . As this occurs, the tooth member  82  engages a longitudinal end of the lower most slat  24  of the stack of slats positioned in the slot  44  of the receiving bin  38  and forces the slat toward the clamping station  34  along the horizontal surface of the slat dispensing station  30 . The size of the opening  48  beneath the end wall  46  of the receiving bin  38  prevents the remaining slats from moving with the lower most slat and retains such slats in the receiving bin. 
     The control unit also triggers the electric motor  98  of the slat conveying mechanism  36  to cause the drive wheels  88  to begin rotating via the drive belts  96 . This preferably occurs simultaneously with activation of the cylinder  76 , or shortly thereafter. As the slat  24  being moved by the cylinder  76  progresses toward the clamping station  34 , it eventually engages between the idler wheels  86  and the driving wheels  88  of the slat conveying mechanism  36 . When this occurs, movement of the slat  24  is taken over by the rotation of the drive wheels  88  and the drive wheels  88  then continue to move the slat along the lower base plate  70  of the clamping station  34 . As the slat  24  continues to move, it eventually triggers the slat position sensor  80  that, in response, sends a signal to the control unit. 
     Having received the signal that a slat  24  has reached the position of the slat position sensor  80 , it should be understood and appreciated that the control unit can be configured to move the slat to any number of specific positions along the lower base plate  70  of the clamping station  34  by controlling the starting and stopping of the driving wheels  88  via control of the electric motor  98 , with additional sensors. In other words, the control unit sees that the first block has been attached and has moved to the next switch that can be positioned back and forth to determine the placement of the second block. Another switch is tripped to determine the placement of the third block which is also adjustable. In this manner, the slat  24  is moved to and stopped at a first position, as shown in FIG. 7, wherein the longitudinal end of the slat farthest from the slat dispensing station  30  is positioned directly beneath the upper horizontal plate  68  of the clamping station  34 . 
     With the slat  24  stopped in the first position, the control unit triggers the cylinder  100  of the block conveying mechanism  37  to cause the pushing ram  104  to move toward the clamping station  34 . As this occurs, the pushing ram  104  engages the lower most block  26  stored in the block holder member  56  and forces it through the opening  64  of the block holder member toward the slat  24 . The block holder surface  58  of the block dispensing station  32  is positioned above the lower base plate  70  of the clamping station  34  by a distance slightly greater than the thickness of the slat  24 . Thus, as the block  26  is translated via the pushing ram  104  of the block conveying system  37 , the block slides over the slat  24  and drops thereon. The pushing ram  104  continues to push the block  26  until it engages against the side plate  72  of the clamping station  34 . The side plate  72  is positioned such that it is aligned with the perimeters of the idler wheels  86  and therefore acts as a guide rail that is flush with an edge of the slat. Thus, as the pushing ram  104  biases the block  26  against the side plate  72  of the clamping station  34 , at least one side of the block is automatically aligned with a widthwise edge of the slat  24 . Simultaneously, the control unit activates the cylinder  66  of the clamping station  34  to force the upper horizontal plate  68  downward against the block  26 . 
     With the upper horizontal plate  68  of the clamping station  34  biasing the block  26  downward against the slat  24  and the pushing ram  104  biasing the block horizontally against the side plate  72  of the clamping station  34  as shown in FIG. 7, the control unit activates the automatic fastening device to force a fastener upwardly through the fastener slot  74  of the lower base plate  70  of the clamping station and into the slat and block. The fastener secures the block  26  and slat  24  together and, thereafter, the control unit then activates the cylinders  66 , 100  to unclamp the block  26  and slat  24  by raising the upper horizontal plate  68  of the clamping station  34  and moving the pushing ram  104  away from the side plate  72 . As the pushing ram  104  returns to its original position, it passes out from under the block holder member  56  and allows the remaining blocks being held by the block holder member to drop down onto the block holder surface  58 . 
     With the first block  26  attached to the slat  24 , the control unit then activates the electric motor  98  to advance and stop the slat  24  at a second position where the longitudinal center of the slat is beneath the upper horizontal plate  68  of the clamping station  34 . With the slat  24  stopped in the second position, the procedures described above are automatically repeated to secure a second block  26  to the slat, as shown in FIG.  8 . Afterwards, the control unit then again activates the electric motor  98  to advance and stop the slat  24  at a third position where the longitudinal end of the slat nearest the slat dispensing station  30  is beneath the upper horizontal plate  68  of the clamping station  34 . Once more, the procedures described above are automatically repeated to secure a third block  26  to the slat  24 , as shown in FIG.  9 . 
     With the above-described steps performed, the formation of a stringer  22  is complete and the control unit once again activates the electric motor  98  to advance the stringer off of the lower base plate  70  of the clamping station  34 . The control unit also simultaneously activates the cylinder  76  of the slat conveying system to return the tooth member  82  to its original position so that the entire procedure can be repeated automatically to form additional stringers  22 . 
     Form the above-description, it should be clear that an operator of the pallet assembly device  28  of the preferred embodiment needs only to stack additional slats  24  in the receiving bin  38  of the slat dispensing station  30  and additional blocks  26  in the block holder member  56  block dispensing station  32  to continuously produce block-style pallet stringers  22 . Furthermore, it should be appreciated that pallet assembly device  28  of the preferred embodiment has substantially fewer moving parts than most prior art pallet assembly devices, thereby reducing the likelihood of breakage. 
     The preferred embodiment of the invention has been described above to explain the principles of the invention and its practical application to thereby enable others skilled in the art to utilize the invention in the best mode known to the inventors. However, as various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. For example, is should be appreciated that, although the pallet assembly device of the preferred embodiment is specifically configured for use assembling the stringers of block-style pallets, the invention could also be utilized to assemble other portions and other types of pallets. Thus, the breadth and scope of the present invention should not be limited by the above-described exemplary embodiment, but should be defined only in accordance with the following claims appended hereto and their equivalents.