Patent Application
20090091073
This invention relates to singulating sheet material/media, and more particularly, to a new and useful ingestion assembly for separating/singulating sheet material such as mailpieces and/or sheets of paper in a sheet singulating apparatus.
Material handling apparatus such as mailing machines commonly employ rollers and/or belts for transporting and separating sheet material. In the context used herein, “sheet material” is used generically to describe any substantially flat, two-dimensional media such as mailpieces, sheets of paper, postcards, laminate, woven material/fabric etc. Oftentimes, a combination of belts and rollers are employed, i.e., one set of rollers opposing a set of belts, to separate individual sheets from a stack of sheet material.
A common singulating apparatus, used in a variety of mailing machines/meters, employs a set of horizontal conveyor belts (typically three) moving in one direction along a transport deck and a pair of rollers disposed above and rotating in a direction opposing the conveyor belts. The belts typically transport a stack of mailpieces toward a V-shaped ingestion area or throat disposed between the rollers and the belts. The V-shaped ingestion area converges such that the rollers and belts define a singulation interface which is initially spring-biased to a closed position, but may open in response to loads imposed by mailpieces entering the ingestion area.
More specifically as mailpieces approach the V-shaped ingestion area, the opposing motion of the upper rollers causes the mailpieces to shingle such that the lowermost mailpiece of the stack enters the singulation interface. Preferably, the ingestion angle, i.e., the apex angle of the V, should be shallow to ensure that mailpieces are separated in the throat before reaching the interface. As the conveyor belts move mailpieces against the upper rollers, the interface opens due to the normal forces acting on the rollers. Furthermore, the friction force developed between the mailpiece and the conveyor belt is designed to exceed the retarding force developed between the mailpiece and the upper rollers such that the mailpiece passes through the interface and is “singulated” from the stack.
A variety of factors associated with the geometry and arrangement of the opposing rollers/belts can be difficult to control and/or to optimize the effectiveness/of the singulating apparatus. Of the various difficulties which can arise, a principal concern relates to leading edge damage as a mailpiece enters the singulating interface. More specifically, as the leading edge of a mailpiece contacts the singulating upper rollers, the leading edge can peel upwardly and fold back upon itself as a consequence of the opposing motion of the rollers. In addition to the leading edge damage, the build-up of thickness can jam and stall the operation of the singulating apparatus.
Moreover, the geometry of, and friction forces developed in connection with, the ingestion assembly, i.e., the combination of the singulating guide and rollers, can impact mailpiece shingling/separation and the effectiveness of the singulating roller(s). More specifically, difficulties are often encountered when processing/singulating: (i) mailpieces spanning a wide range of thicknesses, (ii) a combination of thick and thin mailpieces and/or (iii) mailpieces having a variety of surface finishes i.e., glossy, satin or flat surface finishes. Regarding the former, the geometry of the ingestion area, i.e., principally the ingestion angle, can cause a collection of thin mailpieces, or a single thick mailpiece, to change the effectiveness of the singulating roller. More specifically, a build-up of mailpieces upstream of the singulating roller can lift the ingestion assembly so as to cause multiple mailpieces to pass under the roller without being singulated. Additionally, the thickness of mailpieces contacting the singulating roller can ameliorate or exacerbate the effectiveness of the roller.
Regarding the latter, the surface finish determines the friction coefficient and, consequently, friction forces developed between various elements of the singulating apparatus. More specifically, the surface finish impacts the friction forces developed between (i) individual mailpieces, (ii) mailpieces and the upper ingestion assembly and, (iii) the lowermost mailpiece of the stack and the lower conveyor belts. Generally, the friction forces developed in one of these areas, must be higher or lower than the forces developed in another area. For example, the friction forces developed between the lower conveyor belt and the lowermost mailpiece must be higher than the forces in any other area for successful mailpiece singulation. Additionally, the friction forces developed between the upper ingestion assembly and the contacting mailpieces must be higher than the friction forces generated between individual mailpieces for successful mailpiece shingling. It will be appreciated, therefore, that the surface finish of mailpieces further complicates the shingling/singulation of mailpieces in a singulation apparatus.
A need, therefore, exists for an ingestion assembly for a singulating apparatus which accommodates both thin and thick mailpieces, is reliable, low-cost and mitigates damage to the leading edge portion of sheet material without impacting the efficacy and/or efficiency of a singulation apparatus.
The accompanying drawings illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description given below serve to explain the principles of the invention. As shown throughout the drawings, like reference numerals designate like or corresponding parts.
An ingestion assembly is provided for a singulating apparatus having a conveyor system for moving a stack of sheet material along a feed path. The ingestion assembly is spatially positioned above the conveyor belt and includes at least one singulating roller driven in a direction opposing the motion of the conveyor belt. The ingestion assembly comprises an assembly support rotationally mounting the singulating roller at a downstream end portion and pivotally mounting to the singulating apparatus at an upstream end portion. A movable guide mounts to the assembly support and is positionable relative thereto as a function of a force vector imposed on the guide by the sheet material. Additionally, the moveable guide includes a surface operative to guide the sheet material into a singulating interface which is formed between the singulating roller and the conveyor system. In operation, sheet material enters the throat of the ingestion assembly and contact is made with the moveable guide. When the force vector, imposed by the sheet material, is less than a threshold level, the guide assumes a first position operative to shingle sheet material in preparation for singulation by the singulating roller. When the force vector, is greater than the threshold level, the movable guide assumes a second position operative to pivot the assembly support and increase the singulation interface. Consequently, sheet material having a larger thickness dimension may pass for singulation from the mailpiece stack.
The present invention is described in the context of a singulating apparatus for mailing machines, though the invention is applicable to any singulation module/assembly for separating sheet material. For example, other sheet material handling apparatus which require separation of individual sheets from a stack of sheets include mailpiece sorting machines, copying and facsimile machines, etc. Furthermore, while the invention is described in the context of a singulation apparatus having a plurality of spaced conveyor belts for transporting a stack of sheet material, the apparatus may employ any number of belts, rollers or similar sheet transport devices. Additionally, while the singulating apparatus of the present invention includes singulating rollers which rotate in a direction opposing the movement of the underlying conveyor belts, it should be appreciated that the rollers need not rotate in an opposite direction, but merely move relative to the conveyor belts. For example, the roller may be stationary or rotating the in same direction but at a reduced velocity relative to the conveyor belts such that relative motion effects shingling and singulation of a stack of sheet material.
The invention is principally directed to the ingestion assembly of the singulating module/apparatus or the portion singulating apparatus which is spatially positioned above the conveyor belts. The ingestion assembly also establishes the upper bounds of the ingestion area and defines the upper portion of the V-shaped throat. Furthermore, the ingestion assembly, in combination with the lower conveyor belts, also creates a singulating interface for separating and passing an individual sheet, i.e., the lowermost sheet, from the stack.
This arrangement is more clearly understood by reference to
The singulating apparatus 10 includes a plurality of horizontal conveyor belts 16a, 16b, 16c (all conveyor belts are shown in
The mailpiece stack 12S is conveyed toward the ingestion assembly 20 and into an ingestion area or throat 24. There, the mailpieces 12 are shingled, i.e., the leading edges 12LE thereof, are separated/staggered and, finally, singulated such that the lowermost mailpiece 12L passes downstream of the ingestion assembly 20 and is separated from the stack 12S. Before discussing the operation of the singulation apparatus 10, it will be useful to describe some of the principal elements of the ingestion assembly 20 and the structural interaction between elements.
In
A pair of singulating rollers 50a, 50b (best seen in
In
A first spring biasing device 60 is coupled to the vertical arm 38 of the assembly support 30 and is operative to bias the downstream end portion 30D thereof toward the conveyor belts 16a, 16b, 16c. That is, the spring biasing device 60 produces a moment load M1 (due to the generation of a force couple F1, F2) about the axis 30A to pivot the assembly support 30 i.e., in a clockwise direction, and urge the singulating rollers 50a, 50b against an underlying mailpiece 12. As such, a normal force FN is applied to the interface between (i) the singulating rollers 50a, 50b and the upper face of the mailpiece 12L and (ii) the opposing lower face of the mailpiece 12L and the underlying conveyor belts 16a, 16b, 16c.
To maintain a predefined singulating interface SI between the singulating rollers 50a, 50b and the underlying conveyor belts 16a, 16b, 16c, the ingestion assembly 20 may include a motion limiter 64 to limit the pivot motion of the assembly support 30. More specifically, one or both of the sidewall structures 32a, 32b may include an oversized aperture or arcuate slot 66 for accepting a laterally protruding pin 68, i.e., normal to the surface of the respective one of the sidewall structures 32a, 32b. The pin 68, which is fixedly mounted to a stationary structure of the singulation assembly 10, traverses within the arcuate slot 66 to facilitate pivot motion and abuts each end of the slot 66 to limit pivot motion about the pivot axis 30A. The size and shape of the slot 66 will be determined by the location of the slot 66 relative to the pivot axis 30A and the angular motion accommodated by the motion limiter 64. Again, the singulating interface SI is generally sized to singulate the minimum thickness expected.
A movable singulating guide 70 is pivot mounted to the assembly support 30. Specifically, the singulating guide 70 is disposed between and pivotally mounts to each of the sidewall structures 32a, 32b about an axis of rotation 70A. The singulating guide 70, furthermore, includes a guide surface 72 which faces the ingested mailpieces 12 and defines the upper bounds of the ingestion area 24. The guide surface 72 includes a central web 70W (see
Functionally, the tapered guide ends 70E-1, 70E-2 permit the leading edge of each mailpiece 12 to move under the singulating rollers 50a, 50b before making contact with the rollers 50a, 50b. Accordingly, the guide ends 70E-1, 70E-2 cause the leading edge of each mailpiece 12 to contact the singulating rollers 50a, 50b at a desirable angular position. Generally, a shallow contact angle is most desirable (i.e., contacting the singulating rollers 50a, 50b near the point of tangency TA with a horizontal line) to mitigate damage to the leading edge 12LE of the mailpieces 12. Preferably, the contact angle along the singulating roller should be less than about twenty degrees relative to the horizontal line which intersects or contains the point of tangency TA.
The guide surface 72 and singulating rollers 50a, 50b, furthermore, have a surface finish and normal force which produce a characteristic friction force. This friction force is higher than the friction forces developed between contiguous mailpieces 12. The friction coefficient produced by the guide surface 72 is high relative to the friction coefficient produced by the parent material employed in the construction of the singulating guide 70. In the described embodiment, the guide surface 72 includes a pair of compliant pads 74a, 74b which extend the length of the guide surface and correspond in location and width to each of the singulating rollers 50a, 50b. That is, each of the compliant pads 74a, 74b are aligned with, and have a width dimension substantially equal to, the width of the respective/corresponding singulating roller 50a or 50b. The friction coefficient μfPAD of each of the pads 74a, 74b may be within a range of between about 0.7 to about 1.0 whereas the friction coefficient μfMP between adjacent or contiguous mailpieces may be within a range of between about 0.1 to about 0.5. Furthermore, the friction coefficient μfPM of the parent material, e.g., a thermoplastic composite, may be within a range of between about 0.1 to about 0.3. Generally, however, the compliant pads 74a, 74b produce a friction force which is at least two times greater than the friction force which may be developed between the mailpiece 12 and the parent material employed in the construction of the singulation guide 70. The import of the compliant pads 74a, 74b and the friction properties associated therewith will be made clear when discussing the various operating modes of the inventive ingestion assembly 20.
Similar to the assembly support 30, the singulating guide 70 is pivot mounted such that its downstream end 70D is biased downwardly toward the underlying conveyor belts 16a, 16b, 16c. More specifically, a second spring biasing device 80 produces a moment load about the axis 70A tending to pivot the singulating guide 70 in a clockwise direction as indicated by the arrow RG shown in
The moment load M2 produced by the second spring biasing device 80 is substantially lower or less than the moment load M1 produced by the first spring biasing device 60. In the context used herein “substantially lower” means that the moment load M2 is about one-half to about one-tenth (i.e., 0.5 to about 0.1) of the moment load M1. Stated in another way, the spring rate stiffness κ1 of the first spring biasing device 60 is substantially higher than the spring rate stiffness κ2 of the second spring biasing device 80. When comparing the spring rate stiffness values of the spring biasing devices 60, 80, the relative magnitudes associated with the moment loads M1/M2 may be applied with the same validity. That is, the spring rate stiffness κ1 of the first spring biasing device 60 is about two (2) to ten (10) times greater than the spring rate stiffness κ2 of the second spring biasing device 80.
Consequently, these relationships/values can be used to evaluate the force vectors required to pivot/rotate (i.e., in a counterclockwise direction) (i) singulation guide 70, (ii) the assembly support 30, and/or (iii) the combination of the singulation guide 70 and the assembly support 30. While force vectors V1, V2 (in the direction of the feed path) may not be imposed at precisely the same locations due to the geometry of the ingestion assembly 20, a linear force vector V1 required to rotate the singulation guide 70 is substantially less than the linear force vector V2 required to rotate the assembly support 30 or the combined assembly support and singulation guide 70. The import of this relationship will be appreciated when examining the operation of the ingestion assembly as mailpieces enter the ingestion area or throat 24.
To prevent the singulating guide 70 from contacting/wearing the conveyor belts 16a, 16b, 16c, a second motion limiter 84 may be employed to optimize the angular position of the guide surface 72. Similar to the first motion limiter 64, the second limiter 84 may employ an arcuate slot or channel 86 formed in one or both of the sidewall structures 32a, 32b. The arcuate slot or channel 86 receives a stop pin 88 which protrudes laterally, i.e., inwardly, from the singulating guide 70 and limits the downward pivot motion of the singulating guide 70 relative to the assembly support 30.
While the second motion limiter 86 may include an upper stop limit surface, i.e., incorporated at the lower end of the arcuate slot 86, the assembly support 30 includes a more robust abutment or stop surface 96 to limit the upward motion of the singulating guide 70. Hence, in an operating mode where the singulating guide 70 engages the stop surface 96, the assembly support 30 and singulating guide 70 pivot in unison (i.e., in a counterclockwise direction) and may be viewed as an integrated unit. While the stop surface 96 provides a positive means for transmitting loads acting on the singulation guide 70, e.g., a force vector imposed by a collection of mailpieces or single thick mailpiece, into the assembly support 30, the stop surface 96 is also operative to prevent the tapered guides 70E-1, 70E-2 from contacting the singulating rollers 50a, 50b.
The methodology for establishing the location of the stop surface 96 can be as simple as identifying the position of the singulation guide 70 immediately prior to contacting the singulating rollers 50a, 50b, or involve greater complexity such as a tool to vary the friction forces acting on and between the ingestion assembly, the conveyor belts and/or the underlying mailpieces 12.
The lowermost mailpieces 12L pass under the singulation guide 70 while the remaining mailpieces 12U, stacked thereupon, contact the singulation guide 70. Should the friction forces between mailpieces be sufficiently high, a stack of thin mailpieces 12 imposes a force vector sufficient to counteract the moment load M1 and pivot the singulation guide 70 upward, i.e., in a counterclockwise direction. At the same time, the assembly support 30 remains in its original position, i.e., motionless, due to the high counteracting moment M2 imposed by the first spring biasing device. That is, while the force vector imposed by the mailpieces 12 is sufficiently high to pivot the singulation guide 70, it remains below a threshold level, i.e., a level insufficient to pivot the assembly support 30. Consequently, the position of the singulating rollers 50a, 50b remains fixed and the size of the singulating interface SI remains constant.
Accordingly, mailpieces 12 passing under the singulation guide 70 are retarded by the singulation rollers 50a, 50b while those remaining in contact with the singulation guide 70 continue to be separated. That is, as the singulation guide 70 pivots upward, the ingestion angle becomes more acute or shallow such that as the mailpieces 12 continue toward the singulation roller 50a, 50b, they separate/shingle in preparation for singulation. Additionally, the high friction coefficient produced by the compliant pads 74a, 74b augments shingling by preventing the upper mailpieces 12U from prematurely sliding past the singulation guide 70. That is, the high friction surface prevents the mailpieces 12U from sliding under the singulation guide 70 before being properly separated/shingled.
In
More specifically, upon entering the ingestion area 24, a lower mailpiece 12L contacts the singulation guide 70 prior to contact with the singulating rollers 50a, 50b. Inasmuch as the force vector required to rotate the singulation guide 70, (i.e., to overcome the moment M1 imposed by the second spring biasing device) is low, the mailpiece 12L lifts the guide 70 into abutting engagement with an upper stop surface 96 of the assembly support 30. As the conveyor belts 16a, 16b, 16c continue to drive the motion of the lower mailpiece 12L forward, the force vector V2 becomes sufficiently large to overcome the moment M1 imposed by the first spring biasing device 60. That is, the force vector V2 is equal to or greater than the threshold level, i.e., a level sufficiently high to pivot the assembly support 30. As the assembly support 30 rotates, the singulation rollers 50a, 50b are raised relative to the conveyor belts 16a, 16b, 16c. In
In another embodiment of the invention, shown in
In accordance with this embodiment of the invention, the ingestion assembly 20 defines a friction interface having a friction coefficient which decreases from an upstream end 20U to a downstream end 20D. The friction coefficient may be decreased in a variety of ways such as increasing the hardness of the compliant pads 74a, 74b from the upstream to downstream ends thereof. Alternatively, the ingestion assembly 20 may be configured to include multiple guide surfaces for shingling and guiding the mailpieces 12. For example, the assembly support 30 may be adapted to include guide rails 32R-1, 32R-2 (see
Furthermore, the abutment surface 96 of the assembly support 30 may be located or positioned between the sidewall structures 32a, 32b such that the compliant pads 74a, 74b of the singulation guide 70 gradually recede relative to and between the guide rails 32R-1, 32R-2. That is, an upstream portion 74U of the pads 74a, 74b may be exposed while a downstream portion 74D may be recessed relative to the guide rails 32R-1, 32R-2. Moreover, the guide surfaces of the ingestion assembly 20, i.e., the surfaces which the mailpieces 12 slide upon or contact during singulation, transitions from the compliant pads 74a, 74b to the guide rails 32R-1, 32R-2. Inasmuch as the compliant pads 74a, 74b may be composed of a material having a high friction coefficient, e.g., between 0.8 to 1.0 and the guide rails 32R-1, 32R-2 may be fabricated from a material having a comparatively low friction coefficient, e.g., between 0.2 to 0.4, the friction forces tending to shingle and separate the mailpieces 12 vary or decrease from the upstream portion 20U of the ingestion assembly 20, i.e., corresponding to the exposed portion of the compliant pads 74a, 74b, to the downstream portion 20D i.e., corresponding to the surface of the guide rails 32R-1, 32R-2. Furthermore, when singulating a combination of thick and thin mailpieces, thick mailpieces may slide freely under the low friction coefficient produced by the guide rails 32R-1, 32R-2, while thin mailpieces may be separated and are shingled by the high friction coefficient produced by the compliant pads 74a, 74b.
In accordance with yet another embodiment of the invention, the tapered guide ends 70E-1, 70E-2, recessed web 70W, and spaced conveyor belts 16a, 16b, 16c are adapted to mitigate damage to the leading edge of singulated mailpieces 12, i.e., prevent the singulating rollers 50a, 50b from peeling the leading edge 12LE upwardly during singulation. More specifically, and referring to
In summary, the singulation apparatus 10 and ingestion assembly 20 therefor, reliably shingles and singulates thin and thick sheet material. Thin sheets/mailpieces, which may have a tendency to double-feed, are separated and shingled upstream of the opposing singulating roller 50a, 50b by the geometry and inclination i.e., the ingestion angle, produced by the movable singulation guide 70. Furthermore, the high friction interface produced by the compliant pads 74a, 74b augments the degree of separation between sheets/mailpieces. Thick sheets/mailpieces, which may have a tendency to mis-feed (i.e., become jammed or do not pass the singulating interface, are singulated by pivotally mounting the assembly support. That is, the singulating interface SI. increases in size by causing thick sheets/mailpieces to rotate and lift the singulation rollers 50a, 50b. Furthermore, by varying the location of the abutment surface 76 and the friction coefficient along the underside guide surfaces, i.e., the compliant pads 74a, 74b and guide rails 32R-1, 32R-2, thick sheets/mailpieces may slide freely under the low friction coefficient produced by the guide rails 32R-1, 32R-2, while thin sheets/mailpieces are shingled by the high friction coefficient produced by the compliant pads 74a, 74b. Finally, the singulation guide 70, and, more particularly the interaction between the tapered guide ends 70E-1, 70E-2 thereof and the underlying conveyor belts 16a, 16b, 16c, can be adapted to effect a curved or wave-shaped leading edge profile. As such, the leading edge is structurally stiffened to mitigate damage thereto upon contacting the singulation rollers 50a, 50b.
Although the invention has been described with respect to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention.
