Abstract:
An apparatus for handling and transferring letter mail from and to different sized mail receptacles or containers such as cartridges and mail trays includes a support frame rotatably supporting a platform and intermediate transfer pan. The platform is adapted to receive a letter mail receptacle, and a clamp apparatus is provided to secure the container to the platform. A motor and coaxial shafts, coupled with a clutch, are drivingly engaged with the platform and the intermediate transfer pan. An elevator is provided to move the platform along a longitudinal axis and the platform is rotatable around an axis perpendicular to the longitudinal axis through the operation of the motor, coaxial shafts and clutch, the clutch selectively coupling the coaxial shafts. The platform and the intermediate transfer pan are rotated such that the letter mail originally located in a receptacle clamped on the platform is transferred to the intermediate transfer pan. After the receptacle is emptied of letter mail, it may be replaced with a different receptacle or container having different dimensions into which the letter mail is transferred from the intermediate transfer pan.

Description:
RELATED APPLICATION 
     This application is a continuation-in-part of U.S. application Ser. No. 08/956,155, filed Oct. 22, 1997, now abandoned. 
    
    
     TECHNICAL FIELD 
     This invention relates to a mail tray loader transfer apparatus and, more particularly, to a tray loader uniquely adapted to transferring letter mail from a mail cartridge to a convention mail tray while maintaining the orientation and the sequential position of the letter mail as loaded into the tray. 
     BACKGROUND OF THE INVENTION 
     The United States Postal Service (USPS) uses a sorting system that arranges and positions letter mail into specially designed cartridges. The cartridges are designed to interface with the sorting system, and to maintain the orientation and position of the sorted letter mail. The cartridges are relatively expensive to manufacture. A typical cartridge contains components such as springs, levers and guides that interact with one another for the cartridge to function properly, retaining letter mail as loaded into the cartridge. 
     The sorting system is located at a central or regional processing center operated by the USPS. Approximately, 500 million pieces of letter mail a day may be sorted and positioned into the cartridges. Subsequent to the sorting process, the cartridges loaded with sorted letter mail are shipped from the regional processing center to other locations from which the mail is distributed to the population. A concern in transporting the cartridges from the regional processing center is the possibility that the cartridges may not be returned or if returned the cartridges may have been damaged during the transportation process. Another concern, is the relatively high transportation costs associated with moving the cartridges in part due to the weight of the cartridges, which are generally manufactured of metal. 
     Accordingly, there is a need for a tray loader or transfer apparatus that transfers letter mail located in a cartridge to a conventional lighter and less costly tray. Conventional letter mail trays may have different dimensions than a mail cartridge consequently any transfer apparatus should be able to handle both types of letter mail receptacles. Also there is a need to maintain the original orientation of the letter mail during the transfer process between the cartridge and the conventional tray. These and other needs are addressed by the tray loader of the present invention. 
     SUMMARY OF THE INVENTION 
     The invention provides apparatus for handling letter mail, specifically for transferring letter mail from one container such as a mail cartridge to a second receptacle such as a tray, while maintaining the orientation and order of the individual mail pieces during the transfer. The tray loader includes a pair of coaxial shafts for rotating a transfer platform and intermediate receiving pan. One of the coaxial shafts is motor driven and a clutch selectively couples the other shaft to the first shaft for simultaneous rotation of the shafts. An intermediate transfer pan for receiving letter mail from a first receptacle or container is mounted on the second shaft. A platform adapted to receive a letter mail receptacle is mounted on the first shaft. An elevator moves the platform along a first or longitudinal axis to position a mail cartridge or tray adjacent to the intermediate receiving pan and the platform and pan are rotated around a second axis substantially perpendicular to the first axis, enabling the transfer of letter mail from the mail cartridge to the intermediate receiving pan by gravity. 
     After the letter mail has been emptied from the cartridge into the intermediate receiving pan, the transfer platform is retracted and rotated to allow the cartridge to be replaced with a tray. The transfer platform is then elevated and rotated to position it adjacent to the intermediate receiving pan. The platform and receiving pan are then rotated back to allow the letter mail to transfer by gravity into the tray. Notably, the cartridge and tray typically have different dimensions. A clamping mechanism is provided to clamp the different sized containers to the platform during the process. The operation of the apparatus is controlled with a microprocessor or other machine controller using conventional technology. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present invention and the advantages thereof may be had by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein: 
     FIG. 1 is a perspective view of one embodiment of the tray loader of the present invention; 
     FIGS.  1 ( a ) and  1 ( b ) are perspective views of a mail cartridge and mail tray, respectively. 
     FIG. 2 is a partial front view of the tray loader of FIG. 1 illustrating coaxial roller shafts utilized in the invention; 
     FIGS. 3A-3J are side views of the tray loader in various positions during a transfer process, with the supporting frame not shown in FIGS. 3B-3J; and 
     FIG. 4 is a partial exploded view of the front of the tray loader of FIG. 1 illustrating retractable clamps suitable for use in connection with the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to the Drawings, wherein like numerals represent like parts throughout the several views, there is disclosed a tray loader  100  in accordance with the present invention. 
     Referring to FIGS. 1,  2  and  4  the tray loader  100  of the invention includes a support frame  108  having a pair of columns  110  extending upwardly from the support frame. Extending between columns  110  are coaxial first and second roller shafts,  113  and  112  respectively. (FIG.  2 ). The coaxial roller shafts  112  and  113  are rotatably supported by two concentric pairs of bearings (not shown), two concentric bearings being located within each of the columns  110 . 
     First coaxial shaft  113  is driven by a motor  136  through a belt  140  and sprockets  138  and  138 ′ which are operatively coupled to first coaxial shaft  113  and motor  136  respectively. A clutch  134  is provided to selectively couple second coaxial shaft  112  to first shaft  113  during the transfer process as described in greater detail below. Alternatively, a direct drive may be used, in which case motor  136  would typically be connected to coaxial shaft  113  through a gear reducer (not shown). 
     An intermediate transfer pan  114  includes a pair of arms  116 , connected at each end to a corresponding end of the second coaxial shaft  112 . The opposite end of each arm  116  is connected to a transfer plate  118  that has side panels  120  extending therefrom. The transfer plate  118  and the side panels  120  extend out and from the pair of arms  116  and are configured to accept letter mail  104  transferred from the cartridge  102 . 
     A transfer platform  122  includes a frame  124  that extends from and is rotatably mounted to the first coaxial shaft  113 . The transfer platform  122  further includes a support elevator  126 , including transfer receiver  141  mounted to move within the frame  124 . The transfer platform  122  accepts either a cartridge  102  or a tray  106  loaded onto the transfer platform by a conveyor (not shown) or other conventional means. In operation, cartridges  102  and trays  106  are alternately loaded onto the transfer platform  122 . 
     In the illustrated embodiment, a support elevator  126  is raised and lowered within the frame  124  with a pneumatic cylinder  128 . The cylinder  128  may be hydraulic or pneumatic and is actuated by controller  218  which controls the timing and sequencing of the operation of the tray loader  100  during the transfer process. When a mail receiving receptacle such as at cartridge  102  or tray  106  is loaded onto transfer platform  122 , cylinder  128  is actuated to raise the support platform to position the cartridge or tray adjacent to the transfer pan  114 . Controller  218  is equipped with a “kill switch”  219  which enables an operator to stop the operation of loader  100  in the event that the unit must be shut down due to a jam or other interruption. 
     The transfer platform  122  further includes retractable holding clamp assemblies  130  (FIG. 4) that secure a cartridge  102  or tray  106  to the transfer platform during the transfer operation. The holding clamp assemblies  130  may be operated by one or more hydraulic or pneumatic cylinders and are controlled by controller  218 . In one embodiment, the clamp assemblies  130  are designed to hook over the edges of cartridge  102 , securing the cartridge in the platform during the transfer operation. During the transfer operation, the clamp assemblies  130  also serve to secure a tray  106  in position in the platform  122 . The mail cartridge  102  typically does not have the same dimensions as a mail tray  106 . However, a conventional mail tray  106  is normally relatively light and flexible, typically being formed from cardboard or plastic. Thus, relatively little clamping force is required to hold the tray in position and clamp assemblies  130  have been demonstrated that hold the tray in position by merely pressing against the sides of the tray  106 , rather than clamping the tray tightly in place. Thus, a tray  106  is not required to have the same geometry as a cartridge  102  and the tray loader of the invention has the capability of handling mail receptacles (trays and cartridges) having a range of different geometries during the transfer process. 
     Referring specifically to FIG. 4, clamp assembly  130  includes a sliding clamp,  131  mounted on track  139  for movement along the track in a vertical direction upon actuation of cylinder  137 . Horizontal movement of clamp  131  is controlled by cylinder  135 , which, as will be appreciated, moves the clamp laterally to clamp a cartridge  102  or tray  106  in position on transfer receiver  141  during the transfer process. Clamp assemblies  130  are controlled and actuated by controller  218 . Clamping assemblies may, for example, be actuated by controller  218  upon receipt of a signal from sensor  132  indicating that a tray has been positioned on transfer receiver  141 . 
     One or more sensors  132  are provided to detect that a cartridge or tray is in position and/or that holding clamp assemblies  130  have secured either the cartridge  102  or the tray  106  in the transfer platform  122 . Sensors  132  may be connected to or adjacent to the support elevator  126  and monitored by the controller  218 . A sensor  132  may be provided to detect a defective cartridge  102  or tray  106 , and upon detection the defective cartridge or tray is unloaded from the tray loader instead of proceeding with the transfer process. Sensor or sensors  132  may be contact sensors, proximity sensors, or optical sensors depending upon the particular application and location of the sensor. 
     Referring to FIG. 2, there is shown a front view of the tray loader  100  further illustrating coaxial roller shafts  112  and  113 . The clutch  134  selectively couples shafts  112  and  113  in response to control signals from the controller  218 . Motor  136  is also controlled by the controller  218 . As illustrated, shaft  112  is not continuous across the length of shaft  113  but is part of an assembly including, transfer pan  114 , transfer plate  118 , transfer arms  116 , side panels  120  and shaft  112  which are all welded, bolted or otherwise fastened together so as to move as a single rotational unit. This configuration simplifies the operation of the tray loader  100 . 
     Referring now to FIGS. 3A-3J, side views of the tray loader in various positions during the transfer process are presented. Frame  124  is not shown in FIGS. 3B-3J for the purpose of clarity in illustrating the operation of the tray loader  100 . The tray loader  100  is illustrated in a beginning position (FIG. 3A) and a final position (FIG. 3J) and various intermediate positions (FIGS. 3B-3I) occurring during the tray loading sequence. 
     Referring to FIG. 3A, there is illustrated the tray loader  100  with cartridge  102  containing letter mail  104  positioned in transfer platform  122  at the beginning position of the transfer process. The cartridge  102  is secured in place within the support elevator  126  by retractable clamping assemblies  130  (FIG.  4 ). As illustrated, the support elevator  126  is located at its bottom position within the frame  124 . The transfer plate  118  of intermediate transfer pan  114  is positioned substantially parallel to and directly above the support elevator  126 . Sensor  132  (FIG. 1) generates and transmits a secure signal to the controller  218  when the cartridge  102  has been secured to the support elevator  126 . The controller, in turn initiates the transfer process. 
     Turning now to FIG. 3B, the tray loader  100  is shown in a second, sequential position. Cylinder  128  has been actuated by controller  218  to lift support elevator  126  within frame  124  such that cartridge  102  has been positioned closer to intermediate transfer pan  114  to assist in keeping the letter mail from shifting. Controller  218  has engaged motor  136  and clutch  134  to rotate coaxial shafts  112  and  113  thereby rotating transfer platform  122  and transfer pan  114  as shown. As illustrated, the platform is moveable along a longitudinal axis  129  and rotatable about a second axis  131  (FIG. 2) perpendicular to the longitudinal axis. 
     Referring to FIG. 3C, the transfer platform  122  and intermediate transfer pan  114  are shown rotated to an inverted position, approximately 150 degrees from horizontal. The letter mail  104  has been transferred by gravity from cartridge  102  to intermediate transfer pan  114  by action of gravity. The sequential arrangement of the letter mail  104  located in the intermediate transfer pan  114  remains the same as it was in the cartridge  102 . In one embodiment of the invention, it takes approximately 1 to 2 seconds for the tray loader  100  to move from the position illustrate in FIG. 3A to the position shown in FIG.  3 C. 
     Referring to FIG. 3D, there is illustrated the empty cartridge  102  disengaged from the intermediate transfer pan  114  which now contains the letter mail  104 . The air cylinder  128  is deactuated such that the support elevator  126  and the cartridge  102  are moved away from the intermediate transfer pan  114 . The sequential arrangement of the letter mail  104  located in the intermediate transfer pan  114  is not disturbed during this step of the process. The clutch  134  is disengaged to de-couple coaxial shaft  112  from shaft  113 , thereby allowing transfer platform  122  to move independently of intermediate transfer pan  114 . 
     Motor  136  is engaged to rotate coaxial shaft  113 , returning transfer platform  122  to the position illustrated in FIG.  3 E. After rotation of the transfer platform  122 , holding clamp assemblies  130  release the cartridge  102 . The cartridge  102  is removed from the transform platform by any conventional means, for example a cylinder operated arm or extractor (not shown). The transfer platform  122  is now positioned in a loading position, ready to receive an empty mail tray  106 . In one embodiment, the empty cartridge  102  is simply pushed off of the transfer platform  122  onto a receiving or transfer conveyor, such as an inclined roller conveyor, (not shown) by an empty tray  106  loaded onto the transfer platform. 
     Referring to FIG. 3F, there is illustrated an empty tray  106  positioned in the support elevator  126 . The tray  106  is secured into place by the actuation of the holding clamp assemblies  130  by the controller  218 . The now empty cartridge  102  has been moved off the tray loader  100 . 
     Referring to FIG. 3G, there is illustrated the transfer platform  122  rotated to a position above the letter mail  104  located in the intermediate transfer pan  114 . The intermediate transfer pan  114  is still positioned at approximately 150 degrees from horizontal. The clutch  134  is not engaged with concentric shaft  112  and intermediate transfer pan assembly  114  during the rotation of the transfer platform  122  during this step of the transfer process. As discussed earlier, the transfer platform  122  will not be rotated unless the tray  106  is secured to the support elevator  126  by actuation of the holding clamp assemblies  130 . 
     Referring to FIG. 3H, there is illustrated the tray  106  in contact with the intermediate transfer pan  114 . To achieve this position, the air cylinder  128  is actuated by the controller  218  to move the support elevator  126  within the frame  124  to an extended position, i.e. close to the transfer platform. The transfer platform  122  does not rotate while the support elevator  126  is extended within the frame  124 . Clutch  134  is then actuated to couple coaxial shafts  112  and  113  and motor  136  is engaged to rotate transfer platform  122  and the intermediate transfer pan  114  to the position shown in FIG.  3 I. Intermediate transfer pan  114  remains substantially in with the tray  106  during the rotation. During the rotation, letter mail previously deposited in intermediate transfer pan  114 , moves a short distance by gravity into tray  106 . 
     Air cylinder  128  is deactuated by the controller  218  such that the tray  106  and the support elevator  126  are lowered within the frame  124  to the position illustrated in FIG.  3 J. In this position, where the tray  106  loaded with letter mail  104  may be moved from the tray loader  100  by conventional means such as a cylinder powered extractor or ram onto a transfer conveyor (not shown). Alternatively, the tray  106  loaded with letter mail may simply be pushed from the transfer platform onto the transfer conveyor by the next loaded mail cartridge  102 . 
     Thereafter, the transfer process illustrated by FIGS. 3A through 3J may be repeated. In one embodiment, the throughput of the tray loader  100  has been demonstrated to be approximately six completed transfers per minute. 
     As will be appreciated, the operation of the various components of the tray loader  100  such as the motor  136 , clutch  134 , support elevator cylinder  128  and clamping assemblies  130  may be controlled through the use of conventional limit switches, sensors and controller  218  as is known to those skilled in the art. 
     While the present invention has been described with reference to the illustrated embodiment, it is not intended to limit the invention but, on the contrary, it is intended to cover such alternatives, modifications and equivalents as may be included in the spirit and scope of the invention as defined in the following claims.