Abstract:
A vacuum friction feeder including at least one vacuum friction belt provided with a plurality of holes, a pair of rollers, a table top provided with at least one suction port, an exposure table having a substantially horizontal top surface and a separator. The at least one vacuum friction belt is adapted to rotate around the table top while supported by the rollers such that a suction pressure can be drawn through the plurality of holes provided in the at least one vacuum friction belt as the plurality of holes pass over the suction port. The exposure table is operatively associated with the table top and is adapted to be movable relative to the table top in a plane defined by the substantially horizontal top surface to adjust the portion of the bottommost product in the stack of products exposed to the at least one vacuum friction belt.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional of U.S. Provisional Application Ser. No. 61/023,653, filed Jan. 25, 2008. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention generally relates to a material handling device and, more particularly, to a vacuum friction feeder. 
         [0004]    2. Description of Related Art 
         [0005]    Bottom-feeding friction feeders are used to individually remove flat stock from the bottom side of a stack and sequentially feed the flat stock into another device such as, for example, a printer, a labeler, a dryer, a collator, a folder or an inserter. Conventionally, the stack of flat stock is positioned such that a portion of the bottom sheet is exposed at an angle to one or more rotating rubber belts. By adjusting factors such as the angle of the stack relative to the belts (which is also known as the “wedge”), the speed of the belts etc., it is possible to sequentially draw a sheet of flat stock from the stack and separately feed the sheet into another device or a conveyor. 
         [0006]    One of the problems that exists with conventional friction feeders is that it is often difficult, if not impossible, to feed different types of flat stock (e.g., flat stock which is thick, or rigid, or wide, or limp etc.) using the same friction feeder. Conventional devices have a difficult time feeding long, wide, dense flat stock (e.g., 36″×16″ paper feed bags). In such applications, it is difficult to make appropriate adjustments to the “wedge” to expose an optimal amount of the material to the belts. Therefore, it is difficult to obtain enough control over the amount of exposure, particularly with longer products, to consistently feed product one at a time (i.e., without feeding multiple pieces at a time). 
         [0007]    Another problem with feeding dense (heavy) material is the amount of material that may be loaded into the stack or “hopper”. The angled design of conventional devices limits the amount of material that can be loaded into the hopper. Furthermore, testing has shown that in conventional friction feeders, as the amount of material remaining in the hopper changes (i.e., decreases over time), the belt exposure wedge conditions change. So as the material is feed and the hopper is depleted the feed characteristic is changed causing feed issues. All these problems make it difficult for the operator to setup and run current device in an effective manner. 
         [0008]    Loading various size products is problematic because of the wedge design. Products longer than the feeder have to be supported behind the feeder in order to get any type of consistent feeding. With the conventional wedge design, the height at which the operator has to load the hopper becomes a major issue. 
         [0009]    Feeding limp feed stock is also a problem for conventional friction feeders. In such applications, the product exposure wedge has to be set so close to the leading edge that the back of product becomes basically unsupported, which causes problems feeding when any significant amount of product is loaded in the hopper. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    The present invention is provides a vacuum friction feeder that overcomes the limitations of conventional vacuum friction feeders. In a preferred embodiment, the vacuum friction feeder is a bottom-feed vacuum friction feeder, which is suitable for use in mail handling, printing and in the packaging industry. A vacuum friction feeder according to the invention utilizes novel method of exposing the flat stock (also referred to herein as “product”) to the belt(s). Product is loaded onto a substantially horizontal top surface of an exposure table. 
         [0011]    More particularly, a vacuum friction feeder according to the invention includes at least one vacuum friction belt provided with a plurality of holes, a pair of rollers, a table top provided with at least one suction port, an exposure table having a substantially horizontal top surface and a separator. The at least one vacuum friction belt is adapted to rotate around the table top while supported by the rollers such that a suction pressure can be drawn through the plurality of holes provided in the at least one vacuum friction belt as the plurality of holes pass over the suction port. The substantially horizontal top surface of the exposure table is adapted to support a stack of products such that a portion of a bottommost product in the stack of products extends beyond an edge of the exposure table and is thereby exposed to the at least one vacuum friction belt above the suction port in the table top. The exposure table is operatively associated with the table top and is adapted to be movable relative to the table top in a plane defined by the substantially horizontal top surface to adjust the portion of the bottommost product in the stack of products exposed to the at least one vacuum friction belt. The separator is adapted to be adjustably positionable above the at least one vacuum friction belt such that no more than one product in the stack of products can pass therebetween at one time. 
         [0012]    The vacuum friction feeder according to the invention can be adjusted to feed a wide variety of different product, including heavy, substantially rigid dense product to thin, limp product. In addition, the vacuum friction feeder according to the invention can feed product that is very long and/or very wide. 
         [0013]    The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of an exemplary floor model bottom-feed vacuum friction feeder according to the invention. 
           [0015]      FIG. 2  is an exploded perspective view of the enclosure, electrical panel and operator controls of the vacuum friction feeder shown in  FIG. 1 . 
           [0016]      FIG. 3  is an exploded perspective view of the table assembly of the vacuum friction feeder shown in  FIG. 1 . 
           [0017]      FIG. 4  is an exploded perspective view of the table subassembly of the vacuum friction feeder shown in  FIG. 1 , showing the frames, the rollers, the vacuum channel, drive motor and a portion of the belts. 
           [0018]      FIG. 5  is an exploded perspective view of an exemplary product back guide and product exposure extender fingers according to the invention. 
           [0019]      FIG. 6  is a side elevation view of an exemplary vacuum friction feeder according to the invention disposed in a material handling system. 
           [0020]      FIG. 7  shows both an exploded perspective view and an assembled perspective view of the vacuum plumbing assembly of the vacuum friction feeder shown in  FIG. 1 . 
           [0021]      FIG. 8  is a side elevation view of an exemplary control layout on an operator control panel for a vacuum friction feeder according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]      FIG. 1  shows an exemplary floor model bottom-feed vacuum friction feeder  10  in accordance with the invention. The feeder  10  comprises an enclosure  20  (i.e., a cabinet), at least one and preferably two or more parallel vacuum friction belts  40 , a pair of rollers  50   a ,  50   b  (see also  FIG. 4 ) for supporting the vacuum friction belt(s)  40 , a separator  60 , a pair of opposing product side guides  70 , an exposure table  80 , at least one product back support  90 , an operator control panel  100 , a ported table top  110 , a separator adjuster assembly  120 , a hopper area  130  and an exposure table slide adjuster  140 .  FIG. 4  shows that the table subassembly has a drive motor  30 , which drives (i.e., rotates) the vacuum friction belt(s). 
         [0023]    Superimposed on  FIG. 1  is an X-axis, which extends toward and away from the separator  60  in a plane defined by the top surface of the exposure table  80 . Preferably the top surface of the exposure table  80  is horizontal and parallel to the floor space supporting the vacuum friction feeder  10 . Also superimposed on  FIG. 1  is a Y-axis, which extends perpendicular to the X-axis in the same plane as defined by the top surface of the exposure table  80 . A Z-axis is also superimposed on  FIG. 1 . The Z-axis extends perpendicular to both the X-axis and the Y-axis (i.e., it is vertical). 
         [0024]    In the illustrated embodiment, the separator  60  extends from the separator adjuster assembly  120  and is adjustable in the Z-axis (i.e., upwardly and downwardly) by turning the separator adjusting screw  121 , which is shown in  FIG. 3 . The separator assembly  120  is mounted to a bridge guide  122 , which extends above the vacuum friction belts  40  in a plane parallel to the Y-axis. The bridge guide  122  is supported by a pair of feeder bridge posts  124 , which are mounted to the ported table top  110 . The bridge posts  124  are provided with slots  142  to allow the side guides  70  to move on the Z axis. This is done to allow the side guides  70  to be raised above belts  40  or close to the table top  110 . The separator  60  is held in place by a separator adjusting fork  61   a  and a front support guide mount  61 . The separator  60  can be rotated by loosening its mounting screw. 
         [0025]    The opposing product support guides  70  are also supported by the bridge guide  122 . The product support guides  70  can be moved along the bridge guide  122  to accommodate product of varying width. Generally, it is desirable to adjust the product support guides  70  such that they are spaced apart slightly wider than the width of the product, with the separator  60  centered on the product.  FIG. 3  shows a front perspective and an exploded view of the bridge guide  122  and opposing product support guides  70 . 
         [0026]      FIG. 4  shows a portion of a pair of vacuum friction belts  40  and a pair of rollers  50   a ,  50   b , which support the vacuum friction belts  40 . A timing belt from the drive motor  30  timing pulley  52   a  drives a timing pulley  52   b  which is connected at one end to rear roller drive shaft  51   a , which rotates the rear roller  50   a  and thus drives the vacuum friction belts  40  in the direction shown by the arrow depicted above the belts  40 . The idle shaft  51   b  can be position along the X-axis to tension the friction belts  40  by adjusting belt tension screws  59 . Adjustable bearing belt guides  58   a  are positioned along belt guide shaft  58   b  to keep the vacuum holes in the friction belts  40  in line with vacuum ports  56  in the ported table top  110 . A vacuum box  54  is positioned in contact with the underside of the port table top  110  such that vacuum is transferred through the ported vacuum slots  56 . The vacuum friction belts  40  proximal to the front roller  50   b  are aligned with their holes directly over the ported vacuum slots  56 . The vacuum pulled through the vacuum box  54  creates a suction force through the ported top  110  (See  FIG. 3 ) and transferred to the holes in the vacuum friction belts  40 , which helps grab the bottom sheet or piece of product in the stack. 
         [0027]    The vacuum, which could also be referred to as a negative pressure or suction, is provided by a vacuum blower  200  (see  FIG. 7 ). It will be appreciated that some product may feed better without the use of a vacuum and based solely on the friction provided by the belts  40 . The amount of vacuum produced can also be adjusted by opening or closing a vacuum bleed valve  210 . The blower  200  draws a negative pressure or suction sequentially through the holes in the friction belts  40 , through the slots  56  in the ported table  110 , through vacuum box  54 , through a vacuum offset box  55 , through a tube  220  having an end  221  that communicates via a fitting  222  with an opening  57  in the vacuum offset box  55 . 
         [0028]    The product back support  90  is mounted to the top surface of the exposure table  80 . Preferably, the exposure table  80  is provided with a plurality of mounting locations, which allow the product back support  90  to be adjusted in the X-axis (i.e., closer to or farther away from the separator)  60 . The product back support  90  contacts the rear side of the stack of product, and includes as small wedge  92 , which helps urge the product forward toward the separator  60 . 
         [0029]    The product back support  90  can be adjusted in the X-axis by turning a knob  91  having a threaded end  93  that is received in any of a series of threaded holes  97  in table  80  to reduce a clamping pressure between a bottom plate  141  and the top side of the table  80 . The threaded end  93  of the knob  91  passes, sequentially, through a slot  96  in a rear portion of a block that includes the wedge  92 , a slot  98  in the bottom plate  141  and into threaded hole  97  provided through the table  80 . When the product back support  90  is positioned, where desired, the knob  91  can be turned in the opposite direction to produce a clamping pressure between the bottom plate  141  and the rear portion of the block that includes the wedge  92 . 
         [0030]      FIG. 5  shows an exemplary embodiment of a product back support  90 . In this embodiment, a pair of extenders  94  can be extended forward of the wedge  92 . The extenders  94  allow for additional support in the X-axis when feeding small, limp product. The extenders  94  are biased between the bottom side of the wedge  92  and a rear side of the product back support  90 , and can be fabricated from spring steel. The extenders  94  are connected by a cross-brace  99 , which includes a hole  101  through which the threaded end  93  of the knob  91  passes. It will be appreciated that extenders  94  may not be needed in some applications and are therefore an optional component. 
         [0031]    The exposure table  80 , the opposing product support guides  70 , the product back support  90  and the product front support  123  cooperate to define the hopper area  130 . A stack of flat stock material, which is sometimes referred to herein as “product”, is placed into the hopper area  130 . The same feeder  10  can be quickly adjusted to efficiently feed large products, such as magazine publications, small sized product like post cards, and relatively thick and rigid, such as corrugated cardboard, to very thin, such as 20-lb paper. 
         [0032]    Product is placed into the hopper area  130 . The opposing product support guides  70  are adjusted as necessary to center the front of the product in relation to the separator  60 . The product support guides  70  will be spaced apart slightly wider than the width of the stack of product. The product exposure table  80  is supported by the exposure table slide adjuster  140 . The product exposure table  80  is adjusted such that an optimal portion of the product hangs over the edge of the exposure table  80  toward the vacuum friction belt(s)  40 . The term “optimal portion” as used in this context means the amount of the product necessary to properly feed the product through the feeder one-piece-a-time. This “optimal amount” will differ based on the characteristics of the product. Thick, rigid product will require a greater portion to overhang the edge of the product exposure table  80  than thin, limp product. After the “optimal portion” has been determined for a particular product, this the operator can quickly and easily configure the feeder  10  for subsequent feeding operations. It will be appreciated that if the product is very short and/or limp, the bottom plate  141  can be extended to reach inside the product support guides  70  for additional exposure adjustment. Optional extenders  94  extending from product back support  90  may also be utilized very short and/or limp products. 
         [0033]    Once the exposure table  80  and product support guides  70  have been adjusted, the height of the product separator  60  is adjusted. For thick and rigid product, the bottom edge of the separator  60  can ordinarily be set to 1.5 times the thickness of the product. For thin and limp product, it is usually best to place a piece of the product under the separator  60 , and then lower the separator assembly  120  until the product exhibits a small amount of deflection below the vacuum friction belts  40 . This separation deflection can be adjusted as a test feed is run, to make product flow smooth, with no multiple feeds. Once the separator  60  is properly adjusted, the product back support  90  can be adjusted such that it just slightly greater than the length of the product to load into the hopper area  130 . 
         [0034]    To initially set up the feeder  10  for a particular product, an operator loads a relatively small supply of product into the hopper area  130  and powers up the feeder  10  using the operator control panel  100 . On power up, a vacuum is pulled through the vacuum box  54  positioned beneath the vacuum friction belt(s)  40 . Once a sufficient vacuum has built up, the operator sets the feed speed to a low rate using the operator control panel  100  and depresses and holds a “JOG” button on the operator control panel  100 . This causes the drive motor  30  to drive the vacuum friction belt(s)  40 . The operator observes how the feeder  10  grabs the bottom-most piece of the product in the stack and separates that piece from the remainder of the stack. If necessary, the exposure table  80  can be adjusted along the X-axis to expose a greater or a lesser portion of the product to the vacuum friction belt(s)  40 . In addition, the separator  60  can be raised or lowered along the Z-axis to achieve optimal operation. Once the exposure table  80  and the separator  60  are adjusted to feed the product, the operator adjusts the feed speed and presses a “START” button using the controls on the operator panel  100 . 
         [0035]    The operator control panel  100  contains switches, buttons and potentiometer controls to allow the operator to control the feeder  10 . These controls preferably include: a power switch, a vacuum control switch, a stop button, a JOG button, a START button and a speed potentiometer. The power switch is used to turn the power on or off for the feeder  10 . The vacuum control switch allows the operator to turn the vacuum blower  200  (see  FIG. 7 ) on or off. The stop button disengages the drive motor  30  causing the friction belts  40  to stop. The JOG button engages the drive motor  30 , which drives the friction belts  40  but only while the JOG button is depressed. The START button latches in the drive motor  30  to drive the friction belts  40  until the run latch is opened. The run latch can be opened in several manners which include but are not limited to, the stop button being depressed, the JOG button being depressed, power switch being turned to off or by and interlock to other equipment. The speed potentiometer is infinitely variable from a minimum speed, creeping, to the maximum speed of the drive motor  30 . 
         [0036]    A portion of the vacuum friction belt(s)  40  are exposed beyond the edge of the exposure table  80 , with the remaining portion extending beneath the exposure table  80  the full length of the enclosure  20 . It will be appreciated that the vacuum friction belt(s)  40  and enclosure can be made to any length necessary to feed extremely long and dense products. In addition, the width and number of vacuum friction belt(s)  40  can be varied, as necessary, in order to produce sufficient traction to drive and separate the products in an efficient and consistent manner. The bridge guide  122  and feeder bridge posts  124  can be made to any size to accommodate product of varying size. Counters and other electronics can be incorporated into the feeder to make the feeder a demand, batch or counter feeder. If more accurate starting and stopping is required, a servo drive could replace the drive motor  30 . 
         [0037]    The flat, horizontal exposure table  80  in the hopper area  130  allows for greater amounts a material to be loaded with out changing the dynamics of the bottom-most piece of product as it is being fed to the vacuum friction belt(s)  40 . The use of a hopper area  130  having a flat, horizontal base also makes the feeder much easier to load with automatic loading devices as compared to conventional hoppers that have an angled base to produce a wedge. 
         [0038]    The best mode for practicing the invention takes form in a commercial floor model bottom feed vacuum friction feeder for the printing, direct mail and small packaging markets. In this mode the feeder  10  will be placed in line with a transport base  150 , typically used to inkjet or apply labels, and a conveying unit  160  as shown in  FIG. 6 . 
         [0039]    The invention is intended to feed a variety of product, from 3″×5″ postcard to envelopes, mailers and flat packaging materials. The size of the feeder can be varied to accommodate larger than normal products for customers or markets that require such. 
         [0040]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept.