Flats mail autotrayer system

A method and apparatus is disclosed for combining multiple small stacks of flats mailpieces into a single large stack of mailpieces and then transferring the large stack to a standard flats mail tray, all while maintaining the sequence order of the mail in the accumulated stack. The apparatus is comprised of three primary subsystems: a bridge conveyor, a stack accumulator, and an output tray station. The bridge conveyor carries mailpieces from the exit conveyor of a mail processing machine such as a collator, to the stack accumulator. The stack accumulator combines small stacks of mailpieces into large stacks in a desired sequence. The output tray station provides support for an empty tray as the accumulated mail stack is transferred to the tray, and then releases the filled tray in a controlled manner.

The present invention relates to a method and system for high speed accumulation/stacking of mailpieces and postal tray loading of the same. In particular, the method and system of the present invention comprises an apparatus that combines multiple small stacks of mailpieces into a single large stack of mailpieces in a desired sequence, and then automatically transfers the single large stack into a postal tray. Specifically, the present invention comprises an apparatus that creates an accumulated stack of mail while maintaining the sequence order of the mail in the accumulated stack by selectively placing successive small stacks on the bottom of the accumulated stack, and then selectively transferring the accumulated stack into the postal tray which is then ejected from the apparatus.

BACKGROUND OF THE INVENTION

Flats mail, or large format pieces of mail, are typically transported in a standard United States Postal Service flats mail tray. Transportation of flats mail is necessary for example from a mailer (companies producing large volumes of mail) to post offices, and from one post office to other post offices. In the interests of efficiency and costs reduction, prior to transportation, the flats mailpieces are sorted and/or otherwise processed prior to being placed into the postal trays in a desired sequence.

There are numerous mail processing machines, which process mail and create groups of mail. These mail groups or mail stacks may consist of a single piece or a multitude of pieces. Individual mailpieces range in length from 4 inches to 15.75 inches, in width from 4 inches to 12 inches, and in thickness from 0.007 inches to 1.25 inches. Mail stacks must be transferred into the postal tray on edge, continuously until the tray is filled. Such loading of a mail tray has long been a manual process.

Accordingly, there is a need for a method and apparatus for high speed accumulation/stacking of flats mailpieces and loading of the same into postal trays in a desired sequence. The present invention fulfills such a need.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a method and system for combining multiple small stacks of mailpieces into a single large stack of mailpieces and then transferring the large stack to a standard United States Postal Service flats mail tray, all while maintaining the sequence order of the mail in the accumulated stack, i.e. first pieces processed on top of accumulated stack and last pieces on bottom.

The present invention is comprised of three primary subsystems: a bridge conveyor, a stack accumulator, and an output tray station. The bridge conveyor carries mailpieces from the exit conveyor of a mail processing machine such as a collator (for example, as disclosed in co-pending U.S. patent application entitled “Flats Bundle Collator” concurrently filed herewith, and herein incorporated by reference), to the stack accumulator. The stack accumulator combines small stacks of mailpieces into large stacks in a desired sequence. The output tray station provides support for an empty tray as the accumulated mail stack is transferred to the tray, and then releases the filled tray in a controlled manner.

The mail handling surfaces of the system are oriented so that mail stacks are maintained at a twenty degree incline from horizontal throughout the entire autotraying process which encourages the edges of flats mailpieces to uniformly register against a side belt of the bridge conveyor and/or side rollers of the stack accumulator. This configuration assists in controlling the movement of mailpieces and maintaining the sequence order integrity of the accumulated mail stack.

Accordingly, it is the principle object of the present invention to provide a method and system for high speed traying of mailpieces, and in particular flats mailpieces.

It is also an object of the invention to provide a method and apparatus for accumulating and stacking of small mailpiece groups into a large mailpiece group.

It is an additional object of the present invention to provide an accumulation/stacking system which maintains the sequence order of small mailpiece groups in an accumulated stack.

It is another object of the present invention to provide a system which sequentially receives mailpieces from the exit conveyor of a mail processing machine, delivers the mailpieces to an accumulator/stacking apparatus, stacks the mailpieces in a desired sequence, and delivers the accumulated stack to a tray.

Numerous other advantages and features of the invention will become readily apparent from the detailed description of the preferred embodiment of the invention, from the claims, and from the accompanying drawings in which like numerals are employed to designate like parts throughout the same.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION

While the invention is susceptible of embodiment in many different forms, there is shown in the drawings and will be described herein in detail a preferred embodiment of the invention. It should be understood however that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit and scope of the invention and/or claims of the embodiment illustrated.

With reference now toFIGS. 1–4, the present invention10is generally illustrated as comprising a bridge conveyor20, a stack accumulator50, and an output tray station120, as best seen inFIGS. 2–4.FIG. 1, illustrates an end view illustrating the orientation of the present invention10at a twenty degree angle to the horizon.

The bridge conveyor20can be seen inFIGS. 2 and 3as having a plurality of conveyor belts25and a side belt30which support and guide the individual mail stacks on the bottom and side respectively, and transports the individual mail stacks to the stack accumulator.

The stack accumulator50can be seen inFIGS. 1–3as having bottom rollers55and side rollers60which support and guide the individual mail stacks on the bottom and side respectively. The fork assembly80of the stack accumulator50can also be seen as having a fork weldment81having fork elements82(seeFIGS. 2,7and8) shown between rollers55. A fork actuation air cylinder83actuates the fork assembly to move the fork elements in and out of contact with mailpieces; and a fork lift air cylinder84raises and lowers the fork assembly, as will be described in more detail below.

The output tray station120can be seen generally inFIGS. 2 and 3at the end of the stack accumulator50. The output tray station120receives a tray5, as will be described in more detail below.

FIG. 4shows a schematic view of the present invention10. The bridge conveyor is positioned proximate the exit conveyor of a mail processing machine, such as a collator. A stack height sensor35, which actuates a second stage of the fork lift cylinder as described in more detail below, is positioned just prior to the entrance of the bridge conveyor20. A jam detect sensor40is positioned at the entrance of the bridge conveyor20to determine if a jam has occurred at the entrance of the bridge conveyor.

The stack accumulator50is positioned proximate the end of the bridge conveyor20. Another jam detect sensor65is positioned at the entrance of the stack accumulator50to determine if a jam has occurred at the entrance of the stack accumulator. Towards the end of the stack accumulator, a fork cycle trigger sensor70is located to trigger the fork cycle as will be described in more detail below.

The output tray station120is positioned at the end of the stack accumulator50. As will be described in more detail later, the output tray station receives and supports an empty mail tray for loading of the accumulated stack, and the releases the tray once filled.

Referring now toFIGS. 5 and 6, the bridge conveyor20is shown consisting of the following significant components. Five O-Ring type conveyor belts25, or any suitably number and type of conveyor belts, are provided to contact the bottom mailpiece of an incoming mailpiece stack, and transport the stack to the stack accumulator20. The O-rings are supported and driven along a conveyor platform28by any suitable combination of a drive pulley26and idler pulleys27, as is known in the art. A flat side belt30contacts and drives, via any suitable drive means known in the art, the edges of all mailpieces of the incoming stack. A stack height sensor35(seeFIG. 4) actuates a second stage of lift fork cylinder84when blocked. Finally, the jam detect sensor40is shown positioned at the entrance to the bridge conveyor20, which stops the present invention10when blocked for an excessive amount of time.

Referring now toFIGS. 6–9, the stack accumulator50is shown consisting of the following significant components. A plurality of driven bottom rollers55contact the bottom mailpiece in stack and selectively moves the stack. A plurality of driven side rollers60contact the edges of all of the mailpieces in a stack. These rollers55,60are slightly spaced apart, enough distance to allow the fort lift fingers or elements82to freely pass between.

A jam detect sensor65(FIG. 8) is provided at the entrance of the stack accumulator to stop the present invention, when this sensor is blocked for excessive amount of time.

A fork cycle trigger sensor70(FIG. 4) is positioned towards the end of the stack accumulator to initiate a fork actuation cycle when triggered by the incoming individual stack to the accumulated stack, as described below.

A stack height limit sensor75(FIG. 9) initiates the process of transferring the accumulated stack to the tray when the height of the accumulated stack is great enough to trigger the sensor.

A fork assembly80comprising at least one lift fork element82(eight fingers shown), lifts the accumulated stack off of bottom rollers55, allowing a subsequent individual stack to be moved thereunder.

A top roller assembly85controls the top of accumulated mail stack and triggers the stack height limit sensor75. A side guide assembly90controls the outside of accumulated mail stack, preventing mailpieces from sliding off of the accumulated stack on the outside. A rear flexible guide95controls the back of the accumulated mail stack, preventing mailpieces from sliding off of the accumulated stack in back.

A pusher arm100pushes on the rear of the accumulated stack during stack transfer process. A stack transfer gate105provides a surface for individual mail stacks to register against when they enter the stack accumulator50.

Referring now toFIGS. 10 and 11, the output tray station120is shown consisting of the following significant components. A tray latch assembly125secures an empty tray5in position for accumulated stack transfer, and automatically releases the filled tray5, as described in more detail below.

A tray detect sensor130detects when an empty tray is in position for the accumulated stack transfer process. A tray not-in-place indicator lamp135(seeFIG. 15), operatively connected to the tray detect sensor130, illuminates when an empty tray is not in position for accumulated stack transfer.

An empty tray support ledge140provides support for the bottom lip6(seeFIG. 4) of the empty tray5that is in the accumulated stack transfer position. A full tray support platform145supports the filled tray at an ergonomically correct height for an operator.

A plurality of tray guides150assist the operator to position empty tray onto the output tray station, and guide filled trays when the latch assembly125releases. Flexible mail guides155and a plurality of idler rollers160guide the bottom of accumulated mail stack as it is transferred to tray. Additionally, an emergency stop button170is provided which stops the present invention10when pressed.

The operation of the system will now be described with respect toFIGS. 12–15. System operation begins when a mail stack7is transferred from the exit conveyor of a mail processing machine to the bridge conveyor20of the present invention10. When a mail stack7blocks the stack height sensor35as it passes from the exit conveyor to the bridge conveyor20, the second stage of the lift fork air cylinder84is actuated to raise the accumulated stack to provide additional clearance between the accumulated stack and the underside of the lift fork elements82. This stack height sensor35is positioned prior to entrance of the bridge conveyor20.

Mail stacks7pass through a jam detect sensor beam40as they enter the bridge conveyor20. If the beam is blocked for an excessive amount of time, the control system of the present invention10declares that a mail jam has occurred and the system is stopped. Mail stacks7also pass through a jam detect sensor beam65as they exit the bridge conveyor20and enter the stack accumulator50. If the beam is blocked for an excessive amount of time, the control system of the present invention declares that a mail jam has occurred and the system is stopped.

Mail stacks7are conveyed from the bridge conveyor20into the stack accumulator by bottom belts25and a side belt30. The surface speed of the bridge conveyor belts is identical to that of the bottom rollers55and side rollers60in the stack accumulator50. Mail stacks7are driven into the stack accumulator50by rollers55and60until they stop against the vertical surface of the stack transfer gate105. The side rollers60rotate continuously throughout system operation. The bottom rollers55are paused when the fork cycle is performed.

When the lead edge of an incoming mail stack7passes through the beam of the fork cycle trigger sensor70, the bottom rollers55stop rotating and the lift fork cycle is performed. The fork cycle trigger sensor70is preferably located approximately three inches prior to the gate105. The fork cycle consists of the following series of movements. The lift fork elements82, holding the accumulated stack8, retract between the rollers60until the elements are completely behind the surface of the side rollers60. Thus, the accumulated mail stack drops on top of the incoming mail stack7. The fork elements82next lower to a position where the elements82are below the top surface of the bottom rollers55. Then, the fork elements82extend back into the stack accumulator50, between and/or under the rollers55, and under the accumulated stack8. Finally, the fork elements82rise to a nominal position above the top surface of the bottom rollers55, allowing the subsequent stack7to move under the accumulated stack8.

The fork cycle is repeated for each mail stack7that enters the accumulator50. Again, each time the fork elements82are retracted, the accumulated mail stack8falls on top of the incoming stack7that has just registered against the vertical surface of the gate105. When the elements82of the fork assembly80rise from between the bottom rollers55, the accumulated stack8is raised off of the bottom rollers55so that another incoming stack7can enter the accumulator.

A top roller assembly85operatively mounted to a pivot arm88rests on top of the accumulated mail stack8as the fork cycles are performed. The roller85moves up and down via pivot arm88with the accumulated stack8. The weight of this roller85exerts a pressure to the top of the stack8that assists in maintaining stack integrity.

During the course of a fork cycle, if the top roller pivot arm88blocks the stack height limit sensor beam75when the accumulated mail stack8is resting on the bottom rollers55, the stack transfer process is initiated. The top roller assembly85in conjunction with the stack height limit sensor75acts as the maximum stack height gage.

The stack transfer process consists of the following actions. The bottom rollers55are actuated, the top roller drive motor87is activated, the side guide assembly90is retracted, the gate105is opened, the pusher arm100is actuated, and the tray latch cylinder126is actuated. The accumulated mail stack8is driven on three sides into the mail tray5during the stack transfer process by the bottom rollers55, side rollers60and top roller85. In addition, as the pusher arm100rotates towards the mail tray5, a roller mounted on the end of the pusher arm100stays in contact with the backside of the rear flexible guide95. The resulting effect of this actuation on the mail stack8is similar to that of a wall pushing on the rear of the stack8.

The side guide90is retracted, by any suitable means, during the stack transfer process so that the high friction belt strips92, which are attached to the guide90, do not inhibit the movement of the stack8into the mail tray5.

When the tray latch cylinder126is actuated, a plastic disc127mounted on the end of the cylinder rod is extended towards the tray5. The disc127initially disengages the latch125from the tray5and then pushes on the tray5to ensure that it falls clear of the gate105at the appropriate time within the cycle. The momentum of the mail stack8striking the tray5and force of gravity complete the process of lowering the tray5to the tray support platform145.

When a filled tray5is ejected from the empty tray position, the tray detect sensor130is unblocked. This condition causes the tray not-in-place lamp135to illuminate which alerts the operator that the filled tray5must be removed and an empty tray5installed. If the tray detect sensor130remains unblocked when a stack transfer is initiated, system operation automatically stops.

All drive means and sensors are operatively connected to suitable controllers, such as programable logic controllers to synchronize operation of all assemblies of the present invention. As described above, the present invention provides for constant control of each mail stack, accumulated mail stack, and tray to achieve the accumulating/stacking of individual mail stacks into one accumulated mail stack, in the desired sequence, and the transfer of the accumulated mail stack into the tray. The height of the accumulated stack that is transferred to the mail tray is preferably approximately 12 inches.

It should be understood that the embodiments herein described are merely illustrative of the principles of the present invention. Various modifications may be made by those skilled in the art without departing from the spirit or scope of the claims which follow. Other modifications or substitutions with equivalent elements are also contemplated.