Abstract:
Disclosed is an apparatus and method for manufacturing pallets. The apparatus and method incorporates an assembly table that alternates between an inclined position where the components of the pallet are fastened and a lower, horizontal position where the assembled pallet is transferred to an conveyor.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the manufacture of pallets. In particular, the invention relates to an automated apparatus and method for manufacturing pallets from wooden boards in a safe and efficient manner. 
     BACKGROUND 
     Pallets, particularly wooden pallets, are an indispensable part of industrial and commercial shipping, handling and storage of goods. Pallets are typically formed of a number of spaced, parallel boards or “stringers” connected by a number of spaced, parallel deck boards that are situated perpendicular to the stringers. A pallet has at least one deck in which deck boards are attached (e.g., nailed) to one side of the stringers. As used herein the term pallet means a set of stringers having at least one deck. More commonly, deck boards are attached to both sides of the stringers thereby creating a two-deck pallet. The apparatus and method according to the invention includes the manufacture of both single and double deck pallets. 
     The demand for pallets is never ceasing. This demand is responsible for the development of several machines and methods for automating and increasing the efficiency of pallet manufacture. The majority of these devices fall into two types: large, expensive machines that require substantial space and capital or smaller machines that are not operator friendly or require unnecessary manual labor. U.S. Pat. No. 3,557,439 to Dykeman is an example of the former and U.S. Pat. No. 4,077,106 is an example of the latter. Furthermore, many of the known devices utilize designs that add unnecessary safety risks to the operator such as arms that can fall on an operator&#39;s hands as in U.S. Pat. No. 5,355,575 to Self or free-falling pallets as in U.S. Pat. Nos. 4,492,016 to Smets et al and 5,058,795 to Tonus. 
     Accordingly, a need exists for a pallet manufacturing machine that is compact, economical, efficient and operator friendly. Preferably, the machine requires only one operator and minimizes the physical labor required by the operator. Additionally, the machine should minimize the safety risks to the operator by channeling movement of the pallet away from the operator rather than towards the operator or perpendicular to the operator. 
     OBJECT AND SUMMARY OF THE INVENTION 
     Therefore, an object of the invention is to provide an apparatus and method for efficiently, quickly and safely manufacturing pallets. A further object of the invention is to provide an apparatus and method for manufacturing pallets that is economical in terms of capital investment and manpower. These and additional objects are met by the apparatus and method of the claimed invention. 
     A preferred embodiment of the invention comprises an apparatus for manufacturing pallets comprising an assembly table. The assembly table comprises means for supporting a plurality of stringers situated in a common plane. The apparatus further comprises means for arranging a plurality of deck boards transversely across the stringers and means for fastening the deck boards to the stringers to form a pallet. The apparatus also comprises a transitioning means for lowering the assembly table from an inclined position to a substantially horizontal position where the pallet engages with a conveyor which transfers the pallet to subsequent processing stations. 
     A further embodiment of the invention is a method for manufacturing pallets. The method according to the invention comprises positioning a plurality of stringers on an inclined assembly table and traversing the stringers with a first plurality of deck boards. The deck boards are then fastened (i.e., nailed) to the stringers to form a pallet. The assembly table is then lowered from an inclined position to a substantially horizontal position whereby the pallet engages with a conveyor. The pallet is then transferred from the horizontally positioned assembly table to subsequent processing stations. 
     The foregoing and other objects and advantages of the invention and the manner in which the same are accomplished will become clearer based on the following detailed description taken in conjunction with the accompanying drawings in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of one embodiment of the apparatus according to the invention. 
     FIG. 1A is a perspective view of an assembly table and a single deck pallet. 
     FIG. 2 is a side view of one embodiment of the apparatus according to the invention. 
     FIG. 2A is a perspective view of an assembly table and a double deck pallet. 
     FIG. 3 is a side view of the apparatus of FIG. 1 in which a completed pallet is removed from the assembly table. 
     FIG. 3A is a perspective view of a pallet traveling on a conveyor. 
     FIG. 4 is a cross-sectional view of the apparatus of FIG. 2 taken along line  4 — 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention is an apparatus and method for assembling pallets. Referring now to FIGS. 1 and 1A, a preferred embodiment of the apparatus according to the invention is broadly designated at  10 . The apparatus comprises an assembly table  12  and a generally rectangular frame formed of vertical and horizontal beams  14  and a platform  16  as shown in FIGS. 1 and 4. Two parallel inclined beams  18  complete the frame as shown in FIGS. 1 and 3. The inclined beams  18  should be such that they are capable of providing a means of transit for a movable gantry as discussed in greater detail below. 
     The assembly table  12  is generally rectangular in shape and possesses a proximate end  20  and a distal end  22  in relation to the operator as shown in FIG.  1 . The assembly table  12  comprises means for supporting a plurality of stringers situated in a common plane. In a preferred embodiment, the means for supporting the plurality of stringers consists of at least two and preferably three jigs  24  as shown in FIGS. 1A and 4. The jigs  24  are attached to a supporting structure  13  which forms a portion of the table  12 . The jigs  24  are substantially parallel and extend between the proximate end  20  and the distal end  22  of the assembly table  12 . The jigs  24  receive stringers and securely hold them in place as shown in FIG.  1 A. 
     Preferably the jigs  24  are movably attached to the supporting structure  13  such that they may be adjusted to manufacture pallets of varying width. For example, the jigs  24  may slide along the width of supporting structure  13  and lock into place using clamps or holes and pins or any other appropriate securing means. 
     The supporting structure  13  is pivotally attached to the frame at a pivot point  25  toward the proximate end  20  of the assembly table  12 . The supporting structure  13  and thus the assembly table  12  alternate between an inclined position (as shown in FIG. 1) and a substantially horizontal position (as shown in FIG. 3) by pivoting about pivot point  25 . 
     Referring now to FIGS. 2.2 and  3 , a transitioning means  52  lowers the assembly table  12  from an inclined position in which the distant end of the table is approximately 45° from the horizontal to a substantially horizontal position upon completion of a pallet. The transitioning means  52  may be any device capable of raising and lowering the assembly table  12 . Suitable means include hydraulic cylinders, electric motors and pneumatic cylinders. Preferably the transitioning means  52  is a pneumatic cylinder. 
     Throughout this description various means for moving or changing the position of different elements are described. Those skilled in the art recognize that any appropriate means, such as hydraulic or electric means may be utilized in the practice of the invention without requiring undue experimentation. For purposes of this discussion, however, the apparatus according to the invention will utilize pneumatic means operated by a compressor  15  and control devices such as air manifolds, air lines and switches that are not shown in detail but are well-known to those skilled in the art. For example, all pneumatic devices described herein may be activated by individual hand or foot switches schematically represented in the Figures at  29 . The precise control mechanism utilized by the invention is not critical to the successful practice of the invention and is not addressed further. 
     The apparatus also comprises means for arranging a plurality of deck boards transversely across the stringers. Preferably, the means for arranging comprises a plurality of reciprocating fingers  26  positioned intermediate the stringers as shown in FIG.  1 A. The fingers  26  are arranged in at least two linear rows along the length of the stringers. Each row of fingers  26  has an equal number of fingers  26  thereby establishing a fixed set of paired fingers. 
     Each row of fingers  26  is attached to a reciprocating arm  28  as shown in FIGS. 2 and 4. Each finger  26  possess a length sufficient to traverse the height of the stringers and thereby protrude above the stringers as shown in FIG.  1 A. The reciprocating arm  28  reciprocates between a retracted position where the distal ends of the fingers  26  are below the stringers and an extended position where the distal ends of the fingers  26  are above the stringers. FIGS  1 A,  2 A and  4  show the finger  26  in an extended position. FIG. 3 shows the fingers  26  in a retracted position. Each set of paired fingers  26  acts as a support structure for a deck board when in the extended position. The final or bottom deck board is held in place by non-reciprocating fingers  27  as shown in FIGS. 1A and 2A. Pneumatic cylinders  30  retract and extend the reciprocating arms  28 . As mentioned previously, the operator activates the pneumatic cylinders  30  by means of a hand or foot switch  29 . 
     The apparatus further comprises one or more compressing means that straightens, aligns and assists in holding the deck boards in place on the assembly table  12 . Representative compressing means are shown in FIGS. 1A,  2 A and  4  as movable side pieces  31 . Additional pneumatic cylinders  30  reciprocate the movable side pieces  31  between an expanded and retracted position. The movable side pieces  31  are retracted during placement of the stringers and deck boards. After the deck boards are placed, the side pieces  31  are expanded to compress the outer edges of the deck boards thereby aligning them and holding them in place for fastening. 
     Referring now to FIG. 4, the apparatus according to the invention further comprises means for fastening the deck boards to the stringers to form a pallet. In a preferred embodiment the means for fastening comprises a plurality of nail guns  32  mounted on a movable gantry  34 . The nail guns  32  may be of any type but are preferably of the pneumatic type which are commercially available in hardware stores and home improvement stores. Pneumatic guns are preferred because they may be easily integrated into the pneumatic system controlling other aspects of the apparatus. The movable gantry  34  also supports a supply of nails  36  for each gun and the means for powering the guns (typically electric switches and pneumatic lines not shown). the nail guns  32  are horizontally aligned across the gantry  34  such that at least one nail gun is aligned along the length of each of the stringers as shown in FIG.  4 . Typically this requires that the gantry  34  support at least three nail guns  32 . 
     The movable gantry  34  is supported by and moves along the inclined beams  18  using a traditional wheel and channel system such as the system commonly used in overhead cranes. A set of guide wheels  38  attached to the gantry  34  travel in channels formed within or on the inclined beams  18 . Preferably, the gantry  34  is counterbalanced by a pulley  41  and weight system  40  that aid the operator in moving the gantry  34  as shown in FIG. 1. A handle  42  allows the operator to move the gantry  34  along the inclined beams  18 . 
     The gantry  34  further comprises a height adjusting means  44 . The height adjusting means may be any structure, such as a pneumatic or hydraulic cylinder or spring, that allows for vertical movement upon the application and release of downward pressure upon handle  42 . The embodiments shown in FIGS. 1 and 3 incorporate springs. The springs  44  allow the operator to adjust the height of the nail guns  32  as the guns pass over the stringers and deck boards. Such adjustment is needed when double decked pallets are built. 
     Building double deck pallets requires the inversion of single deck pallets on the assembly table prior to aligning the second set of deck boards as shown in FIG.  2 A. Upon inversion, the pallet is no longer held in place by the stringers in the jigs  24 . Instead, the first set of deck boards rest on top of the jigs  24  thereby raising the overall height of the pallet in relation to the nail guns  32 . While inverted, the pallet is held in place by the fingers  26  and non-reciprocating fingers  27 . 
     The springs  44  allow the operator to lower the nail guns  32  when the first deck is nailed and raise the guns when the second deck is nailed. The raising and lowering of the nail guns  32  is shown in FIGS. 1 and 3. In FIG. 1, the operator applies a downward force on handle  42  when the gantry  34  is positioned over the assembly table  12 . The force is represented by the downward arrow and compressed springs in FIG.  1 . The springs are relaxed when the nail guns  32  are returned to their starting position or when nailing a second deck of boards. The height adjusting means also functions as part of the automatic nailing mechanism which is discussed below. 
     The gantry  34  carrying the nail guns  32  traverses the length of the stringers nailing the deck boards to the stringers. The firing of the nail guns  32  may occur either automatically or manually. The apparatus is provided with an automatic triggering mechanism if automatic operation is desired. The automatic triggering mechanism comprises a plurality of raised protrusions  46  positioned along the inclined beam  18 . The raised protrusions  46  are best illustrated in FIGS. 1 and 3. The plurality of raised protrusions  46  are placed to coincide with the intersection of the stringers and the deck boards situated on the assembly table  12 . As the gantry  34  and nail guns  32  move down the inclined beams  18 , the operator presses on the handle  42  which compresses the springs  44  and brings a smaller lever  48  into close contact with the inclined beam  18  and the raised protrusions  46 . As shown in FIG. 1, the lever  48  engages wit the raised protrusions  46  as the gantry  34  travels down the inclined beam. The lever  48  is connected to an electrical switch  50  that triggers the firing of the nail guns  32  as the nail guns  32  pass over the raised protrusions. The operator raises the gantry  34  upon completion of the nailing, which disengages the triggering mechanism and returns the gantry  34  to its starting position at the top of the inclined beams  18 . Alternatively, the operator can turn off the automatic firing mechanism by bypassing the electrical switch  50  connected to the lever  48 . In this event, the operator activates a trigger (not shown) attached to the handle  42  thereby firing the nail guns  32 . 
     The apparatus further comprises a conveyor  54  for transferring a completed pallet from the assembly table  12  to subsequently processing points. The subsequent processing point represented in the Figures consists of a stacker  55  of a type that is commercially available. The conveyor  54  may be any type of commercial conveyor suitable for use with heavy and rough materials. The embodiment shown in FIGS. 3 and 3A utilizes a two armed conveyor comprising two synchronized endless chains running in parallel that are driven by two sets of drive sockets  56  as shown in FIGS. 2,  3 ,  3 A and  4 . 
     The transfer of a pallet from the assembly table  12  to the conveyor  54  is a function of the design of the assembly table  12  and the conveyor  54 . The transitioning means  52 , pivot point  25 , supporting structure  13  and the attached jigs  24  are designed to allow the assembly table  12  to rotate in a controlled manner from an inclined position to a lower substantially horizontal position. Vertical stops  60  shown in FIG. 4 may be utilized to support the assembly table  12  while it is in a horizontal position. The rotation takes the pallet downward and away from the operator thereby reducing the risk that the operator will be injured by mechanical failure of the assembly table  12 , transitioning means  52  or conveyor  54 . Upon failure of any of these components the pallet simply falls away from the operator rather than towards the operator. 
     The assembly table  12 , more specifically the supporting structure  13  and the attached jigs  24 , are designed to provide an opening for the parallel arms of the conveyor  54  that allows the assembly table  12  to rotate to a position where the top of the jibs  24  are at least co-planar with the conveyor  54  thereby allowing the pallet to come into contact with the conveyor  54  as shown in FIGS. 3 and 3A. In a preferred embodiment, the switch activating the motor  58  for the conveyor  54  is paired with the switch that lowers and raises the assembly table  12  thereby accomplishing both the transfer of a completed pallet and the staging for a new pallet in a single step. 
     The invention also encompasses a method for the manufacture of pallets. The method comprises positioning a plurality of stringers on an inclined assembly table  12 . The step of positioning the stringers preferably comprises securing at least two stringers in at least two substantially parallel and spaced apart jigs  24 . 
     The stringers are then traversed with a plurality of deck boards. In a preferred embodiment, the step of traversing the stringers with deck boards is accomplished utilizing a plurality of reciprocating fingers positioned intermediate the stringers. The stringers reciprocate between a retracted position where the distal ends of the fingers are below the stringers and an extended position where the distal ends are above the stringers and hereby forming supports for the deck boards traversing the stringers. 
     The operator then moves the gantry  34  and the battery of nail guns  32  along the inclined beam  18  in a plane that is parallel to the plane of the inclined assembly table  12 . If the operator chooses automatic operation, the operator applies sufficient pressure to the handle  42  of the gantry  34  to compress the height adjusting means  44  and the lower the nail guns  32  to a position to ensure engagement of the triggering lever  48  with the raised protrusions  46 . Alternatively, the operator may bypass or disengage the automatic nailing feature of the apparatus and manually fire the nail guns  32  using triggers located on the handle  42 . In either instance, the nail guns  32  fire as the nail guns pass the intersections of the stringers and the deck boards. 
     If single deck pallets are desired, the assembly table  12  is then lowered until the pallet engages with the conveyor  54 . The conveyor  54  transfers the single deck pallet to subsequent processing points. 
     If a double deck pallet is desired, the single deck pallet is inverted on the assembly table  12 . Typically the reciprocating fingers  26  are retracted prior to inverting the pallet and extended after inverting the pallet. A second set of deck boards is then nailed to the stringers in the manner described above. 
     The operator lowers the assembly table  12  after the nailing of the second set of deck boards. The assembly table  12  is lowered until the pallet engages with the conveyor  54 . The conveyor  54  transports the pallet to subsequent processing points. 
     The invention has been described in detail, with reference to certain preferred embodiments, in order to enable the reader to practice the invention without undue experimentation. However, a person having ordinary skill in the art will readily recognize that many of the components an parameters may be varied or modified to a certain extent without departing from the scope and spirit of the invention. Furthermore, titles, headings, or the like are provided to enhance the reader&#39;s comprehension of this document, and should not be read as limiting the scope of the present invention. Accordingly, only the following claims and reasonable extensions and equivalents define the intellectual property rights to the invention.