Systems and methods for maintaining the density of grouped sheet articles

Systems and methods are provided for maintaining density and positioning of a grouped sheet articles, such as for feeding of sheet articles from or into the group. One or more pneumatic sensing systems can be used to monitor and control pressure of sheet articles within the group. Dynamic adjustment can be made to the density and position of the sheet articles in the group such as by controlling a motorized belt to move at least a portion of the group of sheet articles in response to an indication to do so from a controller in communication with the pneumatic sensor.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to processing of sheet articles. More particularly, the subject matter disclosed herein relates to systems and methods for maintaining the density of a group of sheet articles, such as for feeding sheet articles from or to the group.

BACKGROUND ART

It is common in many processing technologies to utilize articles automatically fed from a group of articles or to automatically feed articles to or from a group. Feeding systems and stacker systems discussed herein are frequently an integral part of mail piece inserting systems and mail piece sorting systems.

In applications for feeding articles from a group, it can be very desirable to maintain suitable pressure on the group to facilitate and optimize feeding of items from the group. In sheet processing in particular, it is common to provide a group or even a stack of sheet articles and to pull or feed articles from the group either in smaller groups or one by one. Such groups in sheet processing can include, for example, envelopes of any size, insert material for feeding into envelopes or any other suitable sheet material. Groups of sheet articles can be used in sheet processing for feeding of sheet articles from the group or to the group. Envelopes or other sheet articles can be fed from a group of envelopes, which requires pressure maintenance on the group during the feeding process. In a similar manner, envelopes or other sheet articles can be fed to a group of the sheet articles, which also requires pressure maintenance during the feeding process to make room for additional sheet articles. As can be appreciated by those of skill in the art, the use of either a feeding mechanism or a stacker input mechanism imposes pressure control requirements for the group.

When processing envelopes in particular, a conventional technique for processing the envelopes involves holding the group of envelopes where they are all in a vertical orientation in a group and where envelopes can be removed for feeding from one end of the group. As envelopes are removed from the group, it is desirable to keep pressure on the group of envelopes to continue the process. One way to keep pressure on the group of envelopes is to move a belt under the group of envelopes to adjust and maintain desired pressure on the group. Also, some techniques use a mechanism such as a paddle to push against one end of the group of envelopes to apply pressure. In the past, movement of the belt or paddle mechanism has been set to occur during processing of the envelopes at periodic time intervals, such as for example once every 15 milliseconds, to maintain pressure on the remaining envelopes in the group. For a stacker implementation, the process is reversed so that the belt or paddle must be moved every time an envelope is added to the stack to maintain a constant stack pressure.

In light of the above, there remains much room for improvement, particularly with regard to sheet processing, for a more dynamic method for maintaining pressure on a group of articles while processing or removing articles from the group.

SUMMARY

In accordance with this disclosure, novel systems and methods are provided for maintaining the density of grouped sheet articles, such as for feeding of sheet articles from or into the group.

It is an object of the present disclosure therefore to provide novel systems and methods for maintaining the density of grouped sheet articles, such as for feeding of sheet articles from or to the group. This and other objects as may become apparent from the present disclosure are achieved, at least in whole or in part, by the subject matter described herein.

DETAILED DESCRIPTION

In accordance with the present disclosure, novel systems and methods are provided for monitoring, adjusting and maintaining pressure on sheet articles in a group, such as for feeding of sheet articles from the group. The systems and methods described herein can have particular application for use in sheet processing such as, for example, mail inserting systems, mail sorting systems, and any other sheet processing systems or methods utilizing a group of sheet articles.

The term “sheet article” is used herein to designate any sheet article, and can include, for example and without limitation, envelopes, sheet inserts folded or unfolded for insertion into an envelope or folder, and any other sheet materials.

Two common devices, used in mail inserters and mail sorters that feed or stack sheet articles, are envelope feeders and envelope stackers respectively. Devices that feed or stack sheet articles require that the group of sheet articles maintain a pressure against the front section of the feeder or stacker at the location or point where the article is either extracted or inserted. For a feeder, the pressure insures that the envelope is in a position where the feeding mechanism can acquire the envelope in order to “pull” it out of the group. The pressure needs to be controlled since if the pressure is too light, the envelope will not be engaged by the feeder. If the pressure is too high, the feeder may not be able to extract the envelope from the group or more than one envelope will be extracted. For a stacker, the pressure insures that the group of envelopes is pressed against the front face where each envelope is inserted into the stack. The proper pressure ensures that the group of envelopes is not leaning forward or backward and will exert sufficient pressure on the newly arriving envelope to assist in a controlled stop. The controlled stop results from the friction between the newly arriving envelope and the group of envelopes plus the side wall. If the pressure is too high, the friction will be too great, and the new envelope will not be fully added to the stack resulting in poor stack quality, all envelopes not registered against the side wall, or a jam due to little or no insertion into the group.

As disclosed below, the pressure exerted by a group of sheet articles does not have to be measured directly. An air nozzle and air back pressure measurement device can be used to measure the density of the group of sheet articles by sensing the amount of air reflected back to and through the air nozzle by the group of sheet articles instead of the air passing into or through the group of sheet articles. Those skilled in the art may use a variety of terms to relate the pressure that a group of sheet articles may exert on the extraction or insertion point in a sheet article feeder or stacker to the density of the group. The pressure that a group of sheet articles exerts is directly related to the density of the group and can be determined by measuring the amount of air reflected back to the sensor. The amount of air reflected back to the air nozzle is affected by the amount of air that can be forced into or through the group of sheet articles by an air nozzle.

This section describes a pneumatic sensing system that can be used on a variety of sheet article feeders or sheet article stackers to enable the control of the pressure exerted on the feeding or stacking mechanism by a group of sheet articles. One possible representation of a feeding or stacking mechanism that is operable with the pneumatic sensor system is shown inFIGS. 3 through 8. Other possible representations may exist as those skilled in the art are aware of or could design. A pneumatic sensing system as shown inFIG. 1can be used that includes air nozzle72A, a sensor85for measuring the pressure of air passing to sensor85from air nozzle72A, and an air supply90. Second air nozzle72B can be part of another, complete pneumatic sensing system PSS with an identical or similar sensor and air supply. Air supply90can provide outgoing air78, that can be in a stream, through air nozzle72A that is directed at a group of sheet articles SA. Some of air stream78can pass through the group as indicated by escape air79, and some of air stream78can be reflected back as indicated by reflected air80, that can also be in a stream. Reflected air80can pass into air nozzle72A where it is directed to air pressure sensor85. As shown inFIGS. 2A,2B and2C and as known to those familiar with pneumatic sensors, air nozzle72A can have two air passages therethrough wherein an inner, peripheral air passage74can act as a conduit for blowing air therethrough in a direction toward an object. A central air passage76can be defined centrally through air nozzle72A for passage of air therethrough in an opposite direction that has been reflected by an object such as object O inFIG. 2B. Object O for the example described is the side edge of a stack of sheet articles SA. In accordance with the present disclosure, air78can be blown through peripheral air passage74of air nozzle72A against the side of a group of sheet articles. The pressure of reflected air80as reflected by the group of sheet articles can return through central air passage76of air nozzle72A and be measured by sensor85. The measurement of air pressure of reflected air80can indicate the density or pressure of sheet articles in the group. The difference in the pressure of outgoing air78and reflected air80is affected by the density of the stack of sheet articles SA. The lower the density of the stack of sheet articles, the more that escape air79will escape through the group or out the top and bottom of the group. Since the amount of escape air79is proportional to the group density and is a measure of the pressure that the stack will exert on surfaces60and62(FIG. 5A) or roller38and plate35(FIG. 5D), the measurement can be used with controller91for example to control movement of motors MA and/or MB to adjust the density or pressure of the sheet articles in the group. Table 1 shows one example of current values for the stacks of envelopes used on the sheet article processing machine. Those skilled in the art may develop different values based on testing with a variety of sheet article types and feeder or stacker configurations.

For that alternative implementation of using pneumatic sensing system PSS to control the operation of a sheet article stacker system, the principles can be identical. One or more sensors such as sensor85can be used to sense the density or pressure of sheet articles in the group, and the measurement can be used with controller91for example to control movement of motors MA and/or MB to adjust the density or pressure of sheet articles SA in the group. Motors MA or MB can be operated to move any or all of belts B1, and B2to reduce the density or pressure of sheet articles SA, against input roller38and front plate35, to allow additional sheet articles to be added to the stack. Even when used with a stacker system, the density or pressure of sheet articles SA in some situations may need to be increased. If sheet articles SA are not uniform in length or height, a single sensor72A may be used where a stacker system is used, but if sheet articles SA are uniform, then two sensors such as sensors72A and72B can be employed by adding in slide bars similar to52and54.

Referring now toFIG. 3of the drawings, and according to one aspect of the present disclosure, a system generally designated10is shown for maintaining pressure on sheet articles in a group. System10can include a support generally designated20for supporting a plurality of sheet articles (shown later) in a group. Support20can include a surface22that can be horizontal and elongated for supporting a plurality of vertically oriented sheet articles in a group on top of surface22. One or more belts such as belts B1, B2, B3, and B4can extend at least partially in the direction of surface22and can be adapted for moving in a direction toward an end of support20as explained in detail further below. Support20can also include a side wall24that can extend vertically in a direction orthogonal to surface22and extend horizontally the distance of support20. Side wall24can be used for registration of sheet articles against side wall24. An end wall26can intersect with an end of side wall24and extend vertically away from surface22. A movable plate28can be spring loaded and positioned for pressing against the rear of a group of sheet articles. Plate28can include a handle30for ease of moving plate28.FIG. 3of the drawings shows an operator side view of system10andFIG. 4shows the reverse side view.

One or more groups of sheet articles can be supported on surface22of support20. As shown in one aspect, system10as shown inFIG. 3is configured for supporting two separate groups of vertically oriented sheet articles on surface22of support20for seriatim feeding of the sheet articles from surface22to a sheet feeder such as sheet feeder generally designated SF as explained in detail further below. Those skilled in the art will recognize that sheet articles do not have to be maintained in a particular orientation and can be oriented such that the individual sheet articles in a group are on-edge or vertical, or such that the individual sheet articles in a group are horizontal, where they can be stacked, such as for example from under or over accumulation. The orientation is a function of the infeed location40design or the stacker location (not shown) design. Each group of sheet articles can be supported on surface22and biased by plate28toward a feeding location generally designated40. At feeding location40, individual sheet articles from each group can be removed and moved into sheet feeder SF for further processing as explained in detail further below.

System10can use any suitable mechanism or system for moving a group of sheet articles on surface22. For example, plate28can be adapted and used for moving a group of sheet articles on surface22instead of any belts as can be appreciated by those of skill in the art. When belts are utilized, just one or more than one belt for moving a group of sheet articles on surface22can be utilized.FIG. 5Aof the drawings provides a close up view of a portion of system10including support20configured with belts B1, B2, B3and B4. As shown inFIG. 5Bof the drawings, a group of sheet articles generally designated SA, shown for example as a group of envelopes, is shown supported on surface22where sheet articles SA are registered along one side against side wall24and biased by plate28toward feeding location40. Those skilled in the art will recognize that plate28can be driven to add or remove pressure to a group of sheet articles instead or in addition to the belts.

The group of sheet articles SA is positioned on top of belts B1and B2(shown inFIG. 5A) such that belts B1and B2can move in a direction toward feeding location40in order to maintain a desired pressure of sheet articles SA against one another in the group, which is important for feeding of the sheet articles from the group.

As shown inFIG. 5D, a sheet article stacker system, generally designated SS, can operate similarly, but in an opposite direction. In this aspect, feeding location40can be a location for feeding sheet articles such as envelopes to a group on support22, rather than extracting sheet articles from the group as performed by a feeder. For the example shown, an envelope is inserted into the stack from the left39by the compliant roller37and the drive belt36. Pressure control can be maintained against the input roller38and front plate35in a similar manner using the same support structures22,24and using one or more belts, such as B1and B2(additional belts not shown could also be used) and or a driven movable plate such as plate28. Alternately, plate28may be spring loaded to ensure a minimum stack pressure. Belts B1and B1and/or plate28can be moved as desired each time a sheet article is added to the group based on the sensor operation using an air nozzle72A as described further below.

FIGS. 6A and 6Bof the drawings show an example of how belts B1, B2, B3and B4can be driven. Motor MA can be used for driving belts B1and B2, and motor MB can be used for driving belts B3and B4. As best shown inFIG. 6B, motors MA and MB can respectively drive shafts42A and42B to turn rollers44A and44B. Belts46A and46B on rollers44A and44B, respectively, can therefore be driven to rotate and turn pulleys48A and48B, respectively. Rotation of pulleys48A and48B rotates shafts50A and50B, respectively. Belts B1and B2can be attached on rollers on shaft50A such that rotation of shaft50A rotates belts B1and B2. Similarly, belts B3and B4can be attached on rollers on shaft50B such that rotation of shaft50B rotates belts B3and B4. The use of more than two belts and more than one motor provides a differential drive arrangement helpful for processing larger sheet articles, for example large envelopes known as flats. When processing a larger group of sheet articles such as flats F shown inFIG. 6C, the group of flats F can sit on top of belts B1, B2, B3and B4. In this manner, the use of two motors can address skew that can result for example from the differential in material and weight of an envelope on the bottom side (driven by one set of belts, such as belts B1and B2) as compared to the flap side (driven by another set of belts, such as belts B3and B4). As such, motors MA and MB can be controlled and operated selectively at the same or simultaneously different speeds. A side bar52(shown in FIGS.5A and5B) can be used to assist in aligning a group of sheet articles on surface22as they reach feeding location40. Side bar52extends from a side bar base54that can be movably attached to a shaft56where side bar base54can be moved in a transverse direction laterally along shaft56by rotation of knob58(shown inFIG. 4). Side bar base54can therefore be adjusted and positioned as desired for positioning of side bar52, such as to position side bar52between belts B2and B3as shown inFIG. 5Aor to a far side of surface22such as outside of belt B4as shown inFIG. 5C.

With reference to feeding location40and as shown inFIGS. 5A,7A and7B of the drawings, one or more feeding belts such as feeding belts FB, can be provided at feeding location40. Feeding belts can have a plurality of vacuum holes H and can be positioned at the end of surface22for feeding of sheet articles from a group as described below. During operation, feeding belt FB can rotate continuously in a downward direction. Feeding belt FB can be positioned and exposed through slots defined in a feeding plate that can have an upper feeding plate portion60and a lower feeding plate portion62. Lower feeding plate portion62can be pivotally attached with upper feeding plate portion60for pivotal movement of lower feeding plate portion62as described in more detail below. One or more suction cups such as suction cups C, can be attached to lower feeding plate portion62.

As best shown inFIGS. 7A and 7B, separator pins such as pins70can be positioned along one or both sides of a feeding end of a group of sheet articles at feeding location40and used for facilitating seriatim feeding of a single sheet article from a group as described further below. One pair of separator pins70can be positioned proximate suction cup C, and another pair of opposing separator pins can be positioned on side bar base54. One or more air nozzles such as air nozzles72A and72B can be positioned near separator pins70for use with the sensing system described in detail further below.

In accordance with the present disclosure, a sensing system such as pneumatic sensing system generally designated PSS can be provided to monitor the density or pressure of a group of sheet articles using an air nozzle such as air nozzle72A inFIG. 7Afor blowing air on against one side of a group of sheet articles on support22. A second air nozzle72B as shown inFIG. 7Bcan be used to blow air against an opposite side of a group of sheet articles on support22. The use of at least two, opposing air nozzles can be useful for controlling skew of processed sheet articles, especially when the sheet articles being processed are flats. Each air nozzle is connected to its own sensor system PSS and corresponding belt drive motor MA or MB.

During operation of the feeder and referring toFIGS. 8A-8C, the sensing system can be used to monitor the pressure on surfaces60and62created by a group of sheet articles SA so that air nozzle72A (shown previously) can blow air against the side of sheet articles SA such as, for example, at or near area A. Any other suitable area or areas could also be the target for blown air. Air reflected from the sheet articles and passing to the sensor can be used to control movement of belt B1. The controller can be set and configured to cause movement or no movement of belt B1based upon the air pressure sensed. For example, when the pressure of sheet articles SA against one another in the group is not tight enough, a lower than normal amount or pressure of reflected air passes back to the sensor, and the controller can accordingly cause belt B1to move toward feeding location40in order to increase the pressure of sheet articles against one another in the group. When sheet articles SA are too densely packed together in the group, such that a higher than normal amount or pressure of reflected air passes back to the sensor, the controller can cause belt B1to accordingly move away from feeding location40in order to decrease the pressure of sheet articles against one another in the group. Finally, when the group of sheet articles SA is within a desired range or amount of pressure of sheet articles against one another, such that a normal amount or pressure of reflected air passes back to the sensor, the controller can cause belt B1to do nothing.

During operation for feeding of one or more sheet articles from the group, at least lower feeding plate portion62can move from an unengaged and back position to an engaged and forward position where the suction cups on lower feeding plate portion62move forward to engage a sheet article. As shown in the side view illustration ofFIG. 8A, lower feeding plate portion62is in this forward position where suction cup C with a vacuum pulling through suction cup C engages the end sheet article SA1in preparation for removal and feeding of sheet article SA1. Sheet article SA1can be removed from the group by movement of suction cup C away from the group as shown inFIG. 8B. Sheet article SA1is pulled back against feeding belt FB where a vacuum pulling through feeding belt FB causes sheet article SA1to stay against feeding belt FB. Movement of feeding belt FB with sheet article SA1positioned against it further removes sheet article SA1for feeding as shown inFIG. 8C.

The pneumatic sensing and control features of the present disclosure can therefore be used at any or all points during feeding of sheet article SA1to dynamically monitor and control the density and pressure of sheet articles SA against one another in the group and against surfaces60and62or input roller38and front plate35. Referring toFIG. 9, the density and pressure can be automatically sensed as at100. When the air pressure is below an acceptable range as at101, the group is too loosely packed together and adjustments can automatically be made to apply pressure as at104to move the stack in the group feeding direction to increase the density of sheet articles in the group. When the air pressure is above an acceptable range as at102, adjustments can automatically be made to reduce pressure as at105to move the stack in a direction opposite from the group feeding direction to reduce the density of sheet articles in the group. When the air pressure is within an acceptable range as at103, the density is correct and no movement of the group occurs as at106. Also, the use of more than one pneumatic sensing system allows for independent and automatic monitoring and control of different sides of a group of sheet articles, which can be helpful for controlling skew of sheet articles within the group. When using more than one sensing system, one system can control one or more belts under one side of the group of sheet articles, and another system can simultaneously control one or more belts under another, opposite side of the group of sheet articles.

Where it is desirable to feed sheet articles into a group of sheet articles rather than remove sheet articles from the group, such as with a stacker system as discussed previously, sheet articles SA can be inserted into the group or stack from the side as shown inFIG. 5D. Similar adjustments to the pressure or density of the group can be required for use with a stacker system in order for a sheet article SA1to be inserted into the stack. Maintaining the pressure or density of the group is important to operation of a stacker since high pressure or density can prevent a sheet article from fully entering the stack and low pressure or density can result in the sheet article bouncing off the support24or sustaining damage to the leading edge of the sheet article. The control functions ofFIG. 9can remain the same except that the group can be moved toward or away from the stacker input mechanism.