Abstract:
Methods and apparatus ( 10 ) are disclosed for handling pallets (S) to be inspected and sorted. The method can include tipping a substantially vertically oriented pallet (L) in a forward rotational direction to expose and allow inspection of a trailing major ( 17 ) surface of the pallet. A lower portion of the pallet then can be moved to cause the pallet to tip in a rearward rotational direction and land in a substantially horizontal position. The apparatus can include a pallet restraining device ( 16 ) for blocking the motion of an upper portion of the pallet as it tips in the forward rotational direction and a conveyor ( 30 ) for moving the lower portion of the pallet to cause the pallet to tip in the rearward rotational direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/536,908, filed Jan. 16, 2004, which is incorporated herein by this reference. 
     
    
     FIELD  
       [0002]     This application relates to apparatus and methods for handling pallets.  
       BACKGROUND  
       [0003]     Pallets have been used for many years in connection with the storing, shipment, and handling of goods. Pallets are normally constructed of wood and are subject to damage because of the rough handling they receive. Therefore, it is necessary to periodically inspect pallets for damage and wear and to sort pallets according to their condition.  
         [0004]     One example of a conventional pallet sorting system is shown in  FIG. 1 . The illustrated pallet sorting system  100  includes a pallet tilting mechanism  102  that feeds a stack  104  of pallets  106  to an off-bearing conveyor  108 . In operation, the pallet tilting mechanism  102  receives a generally upright stack  104  of pallets  106 , pivots downwardly to tilt the stack  104  to a generally horizontal position, and pushes the stack  104  to displace the pallets  106  along the pallet tilting mechanism  102  and over a support surface  110 . The support surface  110  may be horizontal, or may be inclined at a slight upward angle as shown in  FIG. 1 .  
         [0005]     As the pallets  106  are pushed on their side surfaces over the support surface  110 , the leading pallet  106 ′ of the stack  104  is moved into contact with and temporarily restrained by a pallet restraining arm  112  suspended downwardly from a support structure  114 . The pallet restraining arm  112  has a counterweight  116  and functions to keep the leading pallet  106 ′ generally upright until the advancing stack  104  overcomes the resistance of the pallet restraining arm  112  and discharges the leading pallet  106 ′ from the end of the support surface  110 . When discharged, the leading pallet  106 ′ drops onto a catch plate  118 , and its top edge is caused to pivot forwardly so that the leading surface of the leading pallet  106 ′ (i.e., usually the top major surface of the leading pallet  106 ′) lies in contact with the off-bearing conveyor  108 . As a result, the opposing trailing surface of the leading pallet  106 ′ (i.e., usually the bottom major surface of the leading pallet  106 ′) is now oriented upwardly as the leading pallet  106 ′ moves along the conveyor, which allows for it to be inspected by the operator.  
         [0006]     In a subsequent operation, it is often desirable to “turn over” a pallet moving along the conveyor so that its top surface is oriented upwardly. Such an operation might be done manually or with a device called a flipper that rotates one or more pallets 180 degrees to reorient them as desired.  
         [0007]     Manually turning over the pallets is usually not desired, and for some applications, the costs and/or space requirements of an additional device such as a flipper or other similar device cannot be justified.  
       SUMMARY  
       [0008]     To address these and other problems, the support surface or other similar structure can be configured to allow inspection of both sides of the pallet, as well as to allow each pallet to be placed onto the conveyor with its top surface oriented upwardly, thereby eliminating the need for a subsequent operation to reorient the pallet.  
         [0009]     In some implementations, the support surface has a second pallet restraining arm to supplement the first pallet restraining arm. The first pallet restraining arm functions to restrain the leading pallet from pivoting until the advancing stack overcomes the first pallet restraining arm&#39;s resistance and the leading pallet is discharged. When discharged, the leading pallet drops vertically, such that its upper edge is below the first pallet restraining arm, which allows the pallet to pivot forwardly.  
         [0010]     As the leading pallet pivots forwardly, it contacts the second pallet restraining arm which is positioned to stop additional forward pivoting of the pallet beyond a predetermined range. This range may be adjusted to provide an appropriate opportunity to inspect the trailing surface of the pallet (usually its bottom surface). Meanwhile, while the upper edge of the pallet is restrained, the lower edge of the leading pallet is pulled forwardly by the advancing conveyor. With the forward pivoting halted, the forward movement of the lower edge of the pallet effects a rearward pivoting of the pallet, resulting in the bottom surface of the pallet coming into contact with the conveyor. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]      FIG. 1  is a side view of a prior art pallet sorting system.  
         [0012]      FIG. 2  is a perspective view of a portion of the support surface and the conveyor, showing the leading pallet after it has been pivoted forwardly and is then restrained by the second pallet restraining arm.  
         [0013]      FIG. 3  is a perspective view similar to  FIG. 2 , except showing the lower edge of the leading pallet advancing with the conveyor, having effected a rearward pivoting of the leading pallet.  
         [0014]      FIG. 4  is a perspective view similar to  FIGS. 2 and 3 , except showing the leading pallet just before the bottom surface fully contacts the conveyor.  
         [0015]      FIG. 5  is a perspective view similar to  FIGS. 2-4 , except showing the leading pallet having been advanced through the conveyor for subsequent downstream operations and a next pallet in the stack on the support surface being restrained by the first pallet restraining arm as the handling operation is about to be repeated.  
         [0016]      FIG. 6  is a perspective view of the conveyor and also showing a curved conveyor for a downstream operation.  
         [0017]      FIG. 7  is a perspective view similar to  FIGS. 2-5 , except showing the leading pallet as an upside down pallet that has been tipped past the second pallet restraining arm to reorient the pallet. 
     
    
     DETAILED DESCRIPTION  
       [0018]     Described below are apparatus and methods providing streamlined handling of pallets. An exemplary apparatus is shown in the perspective views of  FIGS. 2-5 , which illustrate a handling operation sequence.  
         [0019]     Referring to  FIG. 2 , the portion of an overall handling system  10  shown in the figures includes a support surface  12  along which a stack S of pallets is displaced in the direction of travel T from right to left in the figures, usually by a pushing mechanism (not shown). Also shown is a leading pallet L that has been discharged from the support surface  12 , dropped to a conveyor  30  and allowed to pivot forwardly (in the direction F) to the position as shown relative to the other pallets in the stack S.  
         [0020]     The support surface  12  may be horizontal or may be inclined in the direction T at a slight angle as shown in the figures. Various devices may be used to displace the pallets along the support surface, such as pushing devices attached to a separate assembly (e.g., a pallet tilting mechanism) or incorporated as part of the support surface.  
         [0021]     The position of the leading pallet L as shown in  FIG. 2 , in which the trailing surface  17  is angled away from the following pallet, provides one opportunity for the operator to inspect this surface. The leading surface  15  of the leading pallet is visible for inspection during several stages of the handling operation.  
         [0022]     Suitable positioning of the leading pallet L, e.g., the forward pivoting as shown in  FIG. 2 , can be achieved in any number of ways. In the illustrated implementation, the upper edge of the leading pallet L is allowed to pivot forwardly until it contacts a second pallet restraining arm  16 .  
         [0023]     The second pallet restraining arm  16  is spaced forwardly of a first pallet restraining arm  14  in the direction T. In  FIG. 2 , the first pallet restraining arm  14  is shown restraining a next pallet of the stack S that has not yet been discharged from the support surface  12 . In the illustrated implementation, the first and second pallet restraining arms  14  and  16  are suspended from above to contact upper portions of the pallets at different stages during the handling operation. In alternative implementations, one or both of the first and second pallet restraining arms  14  and  16  can be configured to project inwardly from opposite sides of the support surface  12  and to contact the side portions of the pallets instead of the upper portions of the pallets.  
         [0024]     In the illustrated implementation, the first pallet restraining arm  14  has a counterweight  18  and is pivotably connected to a supporting member, such as a support frame  22  as shown in  FIG. 2 . In operation, the first pallet restraining arm  14  serves to restrain the pallet about to be discharged until the advancing stack S overcomes the first pallet restraining arm&#39;s resistance and discharges the pallet from the support surface  12 .  
         [0025]     The first pallet restraining arm  14  and the conveyor  30  are positioned relative to each other such that discharged pallets can pivot forwardly without contacting the first pallet restraining arm  14 . In the illustrated implementation, the conveyor  30  is positioned at a lower height than the support surface  12 , which allows a discharged pallet to pivot forwardly without interference from the first pallet restraining arm  14 .  
         [0026]     The second pallet restraining arm  16  can be connected to same supporting member as the first pallet restraining arm  14 , i.e., to the support frame  22  as shown, or to a separate member. In the illustrated implementation, the second pallet restraining arm  16  has a counterweight  20 . The second pallet restraining arm  16  can have an adjustment device  24  that permits its free end to be angled as desired. In the illustrated implementation, the second pallet restraining arm  16  can pivot, which tends to soften the impact when the leading pallet L initially comes into contact with the second pallet restraining arm  16 . The pivoting action of the second pallet restraining arm  16  also allows an operator to easily reorient an occasional upside down pallet by manually pivoting the pallet in the forward direction F past the second pallet restraining arm  16 .  
         [0027]     Next in sequence after  FIG. 2 ,  FIG. 3  shows the leading pallet L after it has begun to pivot rearwardly in the direction R. The lower edge of the pallet L has been displaced forwardly by the advancing conveyor  30  while the upper edge was restrained by the second pallet restraining arm  16 , thereby effecting a pivoting of the pallet L in the rearward direction. Depending upon the relative positioning of the second pallet restraining arm  16  and the forward end of the stack S, the upper edges of the pallet L may slide along the next pallet of the stack S as the pallet pivots rearwardly. The rearward pivoting of the pallet L can be carried out such that less impact results, and thus no separate cushion arm projecting from the conveyor  30  is required, although one could be used if desired.  
         [0028]      FIG. 4  shows the pallet L just before the trailing surface makes contact with the conveyor.  FIG. 5  shows the pallet L with its top surface facing upwardly and moving in the direction T from the conveyor to a subsequent downstream operation and just before the process is about to be repeated for the next pallet N of the stack S.  
         [0029]     As shown, the conveyor  30  is positioned downstream of the support surface  12 . The conveyor  30  is typically operated intermittently to provide some delay as necessary between various steps of the operation. Such intermittent operation can be programmed to occur on a predetermined cycle, or may be controlled by the operator, i.e., through use of a control to start and stop the conveyor  30 .  
         [0030]     As best shown in  FIG. 6 , the receiving area where the leading pallet L being discharged is received by the conveyor  30  can be configured to assist in absorbing the shock of the dropping pallet and in causing a lower edge of the pallet to contact the convey  30 . According to the illustrated implementation, the conveyor  30  has a member, such as a bar  32  as shown in  FIG. 6 , that is sufficiently strong to absorb the impact of pallets and is sized and/or shaped such that only one edge of a lower end of the pallet L tends to contact the moving belt of the conveyor, which tends to cause the pallet L to pivot rather than to remain upright as the belt continues to advance.  
         [0031]     As also shown in  FIG. 6 , the conveyor  30  can lead to additional downstream areas, such as, e.g., a curved conveyor  34  as partially shown in the figure. A curved conveyor is desirable because the operator can occupy the smaller area on the inner side of the curved conveyor (which reduces the distance he must travel), whereas the area on the outer side of the curve conveyor can “fan out” with links to multiple other areas, e.g., different sorting designations.  
         [0032]     The support surface  12  and arrangement of the first and second pallet restraining arms  14  and  16  has been described consistent with a role of receiving pallets from an upstream operation, such as from a pallet tilting mechanism (sometimes referred to as a “tipper”), and distributing pallets for subsequent downstream operations. The support surface  12  functions to receive and guide pallets along their side surfaces, and thus can be used in other situations, including cases without other upstream and/or downstream operations. The first and second pallet restraining arms  14  and  16 , and particularly the second pallet restraining arm  16 , can be used in applications other than as illustrated in connection with the support surface  12 . For example, the concept of the second pallet restraining arm  16  can be used in any application where it may be desirable to rotate an object, such as a pallet, from its upright orientation to a generally level orientation, in either direction of rotation depending upon the particular circumstances.  
         [0033]     If desired, one or more aspects of the operation of the second pallet restraining arm  16  can be automated. Referring to the illustrated implementation, power can be provided, e.g., to permit the second pallet restraining arm  16  to “unlatch” and allow movement of a pallet past the second pallet restraining arm  16  when pivoted forwardly in the direction F. This may be advantageous in situations where minimal manual handling of pallets is desired. A powered second pallet restraining arm  16  may be configured in a longer length and with an attached idler wheel at its free end to facilitate automatic handling.  
         [0034]      FIG. 7  shows the overall handling system  10  with optional first and second actuators  36  and  38  connected to the first and second pallet restraining arms  14  and  16 , respectively. The first and second actuators  36  and  38  can be used to control the movement of the leading pallet L. The first actuator  36  can be triggered to move the first pallet restraining arm  14  and thereby allow the leading pallet L to drop from the support surface  12  and to begin tipping in the forward pivot direction F. The second actuator  38  can be triggered to move the second pallet restraining arm  16 , e.g. to reorient upside down pallets by allowing the upside down pallets to continue tipping in the forward pivot direction F. The first and second actuators  36  and  38  can be triggered automatically, such as at a given time interval or in response to a signal from a sensor, or manually by an operator, such as by pushing a button.  
         [0035]     In  FIG. 7 , the leading pallet L is shown as an upside down pallet with its leading surface  15  as its bottom surface and its trailing surface  17  as its top surface. After being dropped from the support surface  12 , the leading pallet L is allowed to continue tipping in the forward pivot direction F by manually pushing the leading pallet L past the second pallet restraining arm  16  or by triggering the second actuator  38  to move the second pallet restraining arm  16 . In this way, the leading pallet L can be reoriented to match the other pallets traveling along the conveyor  30 . After the upper portion of the leading pallet has tipped past the second pallet restraining arm  16 , the second pallet restraining arm  16  can be returned to its original position, such as by the force of gravity acting on the counterweight  20  or by reversing the action of the second actuator  36 .  
         [0036]     The described arm arrangement can be implemented in conjunction with a pallet repair table having a pair of separate conveyor belts spaced from each other (instead of the single belt shown in the figures) and an integrated pallet tipping arrangement.  
         [0037]     Although the invention has been disclosed in this patent application by reference to the details of some preferred embodiments, it is to be understood that this disclosure is intended in an illustrative rather than in a limiting sense, as it is contemplated that modifications will readily occur to those skilled in the art within the spirit of the invention.