Abstract:
A system for moving envelopes including a stacking system for creating or placing stack of envelopes on a support surface. The stack of envelopes has a plurality of gaps with each gap being located between adjacent envelopes of the stack. The system further includes a suction head for applying suction to the stack of envelopes to pull air through the plurality of gaps to aid in lifting the stack of envelopes.

Description:
The present invention is directed to an apparatus and method for moving envelopes, and more particularly, to an apparatus and method for moving envelopes utilizing suction forces. 
     BACKGROUND 
     In envelope manufacturing, processing and handling operations it may be desired to move relatively large numbers of envelopes in a rapid manner. In particular it is often desired to lift and move discreet stacks of envelopes. In order to lift and move a stack of envelopes the stack may be gripped between a pair of opposed arms and then lifted and moved. 
     However, the number of envelopes that can be lifted in this manner is limited. More particularly, envelopes typically have a greater thickness or a greater number of plies at certain portions (i.e. the center of the envelope) as compared to other (i.e. outer) portions of the envelope. Thus when a relatively large number of envelopes are gripped and pressed together the greater thickness at the center of the envelopes limits the compression forces that can be applied to the outer edges of the envelope, which results in an unstable gripped stack. This phenomenon can be replicated when a person attempts to grip a large number of envelopes (i.e. an envelope stack one or several feet long) between the person&#39;s arms, and the gripped stack bows outwardly until the envelopes spray apart. Accordingly, there is a need for an improved apparatus and method for gripping and moving stacks of envelopes. 
     SUMMARY 
     In one embodiment, the present invention is an apparatus and method that can securely grip and/or move a stack of envelopes. In particular, in one embodiment the invention is a system for moving envelopes including a stacking system for creating or placing stack of envelopes on a support surface. The stack of envelopes has a plurality of gaps with each gap being located between adjacent envelopes of the stack. The system further includes a suction head for applying suction to the stack of envelopes to pull air through the plurality of gaps to aid in lifting the stack of envelopes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a rear view of an envelope shown in its closed position; 
         FIG. 2  is a rear view of the envelope of  FIG. 1 , shown in its open position; 
         FIG. 3  is a bottom perspective view of a suction head; 
         FIG. 4  is a top perspective view of the suction head of  FIG. 3 ; 
         FIG. 5  is a front perspective view of an envelope processing apparatus as an envelope stack is initially formed; 
         FIG. 6  is a front perspective view of the envelope processing apparatus of  FIG. 5 , with a fully formed envelope stack; 
         FIG. 7  is a front perspective view of the envelope processing apparatus of  FIG. 6 , with an envelope moving apparatus lowered over the envelope stack; 
         FIG. 7A  is a front perspective view of the area  7 A indicated in  FIG. 7 ; 
         FIG. 8  is a side view of the suction head of the envelope moving apparatus and envelope stack of  FIG. 7A  with its gripping arms in a disengaged position; 
         FIG. 8A  is a side view of the suction head and envelope stack of  FIG. 8 , with the gripping arms in an engaged position; 
         FIG. 8B  is an alternate side view of the suction head and envelope stack of  FIG. 8 , with the gripping arms in an engaged position; 
         FIG. 9  is a front perspective view of the suction head and envelope stack of  FIG. 7A , with portions of the suction head shown in hidden lines; 
         FIG. 10  is a cross section view of the suction head and envelope stack of  FIG. 9 ; 
         FIG. 11  is a front perspective view of the envelope moving apparatus and envelope stack of  FIG. 7A , with the envelope stack lifted off of the support surface; and 
         FIG. 12  is a front perspective view of the envelope moving apparatus and envelope stack of  FIG. 11 , positioned over a packaging box. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  illustrate a standard rectangular envelope  10  in its closed and open positions, respectively. The envelope  10  includes a pair of side flaps  12 , a bottom flap  14 , a top flap  16  (commonly called a seal flap) and a front panel  18 . The side flaps  12 , bottom flap  14  and top flap  16  are each foldable on top of the front panel  18  and adhered together to form the envelope  10 . The top flap  16  is movable or pivotable to an open position ( FIG. 2 ) to provide access to the inner cavity  20  of the envelope  10 , and includes an adhesive strip or strips  22  to seal the envelope  10  in the well-known manner. 
     The inner cavity  20  includes a mouth  21  that is selectively covered by the top flap  16  ( FIG. 1 ). However, the envelope  10  can take a wide variety of shapes and configurations beyond that specifically shown in  FIGS. 1 and 2 . For example, besides the diagonal seam envelope  10  shown in  FIGS. 1 and 2 , the envelope may be a side-seam envelope. The envelope  10  can include various windows and/or openings in the front panel  18 , and may have various shapes and sizes, such as letter-sized envelopes, routing envelopes, double stuffed envelopes (i.e., a return envelope located in an outer mailing envelope) and the like. 
     A plurality of envelopes  10  may be stacked and/or compiled using a mechanized assembly, apparatus or envelope stacking machine, such as the machine  30  shown in  FIG. 5 . In the illustrated embodiment, the machine  30  includes a set of three co-axial spiral wheels or discs  32 , also known as delivery spiders, located at the end of, or adjacent to, a support table or support surface  34 . Each spiral wheel  32  includes a set of spiral slots  36  extending in a general circumferential direction out to the outer edges of the associated spiral wheel  32 . Each of the spiral slots  36  is shaped to receive an envelope  10  therein (i.e., envelope  10 ′ of  FIG. 5 ) by an envelope feeding device (not shown) as the spiral wheels  32  rotate about their central axes. 
     In order to commence the stacking operation, the spiral wheels  32  are rotated in the direction of arrow A as envelopes  10  are fed into the spiral slots  36  of the spiral wheels  32 . The machine  30  includes a support carriage  40  including a pair of generally vertically-extending backing bars  42  which extend through a pair of backing bar slots  44  formed in the table  34 . As the spiral wheels  32  pass through or adjacent to the support carriage  40  or table  34 , the lower edge of each envelope  10  that is held in the slots  36  of the spiral wheels  32  contacts the a set of stripping fingers (not shown) coupled to the table  34  and/or carriage  40 , thereby retracting the envelope  10  out of the spiral slots  36  upon continued rotation of the spiral wheels  32 . 
     The first envelope  10  deposited on the table  34  by the spiral wheels  32  engages the backing bars  42  such that the backing bars  42  provide support to the first-deposited envelope  10  (as well as subsequent envelopes  10  deposited on the table  34 ). In this manner, as envelopes  10  are fed into the spiral wheels  32  at an upstream location of the support table  34 , the rotating spiral wheels  32  (i.e. the envelope delivery mechanism in this embodiment) continuously deposit or form an upright stack of envelopes  10  on the support table  34 . 
     As the spiral wheels  32  continue to rotate and deposit envelopes  10 , a partial stack of envelopes  48  is created on the table. However, it should be understood that instead of the spiral wheels  32 , various other methods of depositing the envelopes  10  onto the support table  34  may be utilized. For example, a vacuum wheel or other similar devices may be utilized as the envelope delivery mechanism to deposit or place the envelopes  10  on the support table  34 . 
     The backing bars  42 /support carriage  40  are movable in the downstream direction B (i.e., along the length of the support table  34 ) to accommodate the growing length of the stack of envelopes  48 . As the spiral wheels  32  continue to deposit envelopes  10  on the support table  34 , the stack  48  grows and the backing bars  42 /support carriage  40  move downstream to accommodate the growing stack  48 . As can be seen in  FIG. 6 , eventually a full stack  48  of envelopes  10  is created after a predetermined number of envelopes  10  are located on the support table  34 . Although the stack  48  extends generally horizontally in the illustrated embodiment, the stack  48  could also extend generally vertically if desired. 
     The stack of envelopes  48  created on the table  34  can include any of a wide variety of numbers of envelopes  10 , such as at least about 100, at least about 500, at least about 750, at least about 1000, or less than 100 or more than 1000 envelopes, depending upon the desires of the operator. The outer edges of each envelope  10  in the stack  48  may be generally aligned such that the stack of envelopes  48  forms a generally rectangular prism. This rectangular prism can be viewed as a “slotted” rectangular prism in that a series of slots or gaps (i.e. between each adjacent envelope  10 ) extend throughout the height of the rectangular prism. 
     Once the full stack of envelopes  48  is created, the envelope stack  48  may be indexed downstream, such as by another set of moving fingers (not shown) that fit through the slots  44  of the table  34  at an upstream location of the stack  48 . The moving fingers and backing bars  42  are then moved downstream in a coordinated manner to slide the stack  48  downstream along the table  34 . Next, an envelope moving apparatus  50  is lowered on top of or adjacent to the stack of envelopes  48  ( FIG. 7 ). 
     The envelope moving apparatus  50  includes a suction head or picking head  52 , as shown in  FIGS. 3 and 4 . The suction head  52  includes a pair of opposed generally parallel side walls  54 , a pair of opposed generally parallel end walls  56 , and a backing wall  58  oriented generally perpendicular to the side walls  54  and end walls  56 . The side walls  54 , end walls  56  and backing wall  58  define a suction cavity  60  therebetween. The suction cavity  60  has a generally rectangular prism shape and has a mouth  62  located between the bottom (free) edges of the end walls  54  and side walls  56  and opposite the backing wall  58 . The backing wall  58  (or alternately one of the side walls  54  or end walls  56 ) includes a suction port  64  formed therein which communicates with the suction cavity  60 . The suction port  64  may be operatively coupled to a suction or vacuum source  66  via a connection, such as flexible tubing  68  (see  FIGS. 7 and 7A ). In this manner when the suction source  66  is operated a reduced pressure or suction is created in the suction cavity  60 . 
     The suction head  52  includes a lip  71  having a generally flat lower surface  70  which extends around the perimeter of the mouth  62  of the suction cavity  60 . The lower surface  70  is oriented generally perpendicular to the side walls  54  and end walls  56 , and generally parallel to the backing wall  58  of the suction head  52 . The lower surface  70  can have a variety of widths C ( FIG. 3 ), but preferably has a width of at least about ¼ inch, or at least about ⅜ inch, or at least about ½ inch, or at least about 1 inch. 
     The lip  70  can be made of a variety of materials. For example, the lip  70  can be made of a relatively rigid or stiff material, such as metal (i.e. steel, aluminum or the like) having a hardness of at least about 25 Rockwell C, or can be made of plastic. Alternately the lip  70  can be made of a relatively soft or pliable material, such as foam (i.e. open or closed cell foam) having a hardness of less than about 60 Shore A. Thus the lip  70  can be made of porous or non-porous material. The suction head  52  can be made of a variety of materials, such as metal, plastic or the like, and the lip  70  can be made of the same materials as the suction head  52 . When the lip  70  is made of foam the foam can be coupled to or located on the lower perimeter of the suction head  52 . 
     As shown in  FIG. 3 , the suction head  52  includes a protrusion  72  in the form of a grid located in the mouth  62  of the suction cavity  60  to prevent envelopes  10  or other large debris from being sucked therethrough. Various other shapes or configurations of protrusions  72  besides the grid shown herein may be utilized to prevent the envelopes  10  or other debris from entering the suction cavity  60 . 
     As shown in  FIGS. 7-12 , the suction head  52  and/or envelope moving apparatus  50  may include a compression device in the form of a pair of opposed sets of gripping arms  74 ,  76 . One pair of gripping arms  74  is located on or adjacent to one of the end walls  56 , and the other pair of gripping arms  76  is located on or adjacent to the other opposed end wall  56 .  FIG. 8  illustrates the gripping arms  74 ,  76  in their retracted or non-gripping position. As shown in  FIG. 8A , the envelope stack  48  and/or gripping arms  74 ,  76  are sized and configured such that the envelope stack  48  can be received between the gripping arms  74 ,  76 . 
     In order to grip and lift the envelope stack  48 , the envelope moving apparatus  50  and/or suction head  52  is first lowered over the envelope stack  48  (as shown in FIGS.  7 A and  8 - 10 ) such that the lip  70  and/or suction cavity  60  is located on or adjacent to the envelope stack  48 . The envelope moving apparatus  50  and/or suction head  52  may be lowered such that the lip  70  engages the top surface of the envelope stack  48 . 
     The gripping arms  74 ,  76  are then moved or pivoted to their gripping positions, as shown in  FIG. 8A and 8B , such that the gripping arms  74 ,  76  compress the stack of envelopes  48  therebetween. In the embodiment shown in  FIG. 8A , the lower ends of the envelope stack  48  is compressed more than the upper ends of the envelope stack  48  due to the nature of the pivoting motion of the gripping arms  74 ,  76 . In the embodiment shown in  FIG. 8B , each envelope  10  of the envelope stack  48  may an increased thickness along its upper edge. For example, each envelope  10  of  FIG. 8B  may include an insert (such as a coupon, advertising material or the like) and/or a top flap  16  located adjacent its upper edge which increases the thickness of the stack  48  along the upper edge of  FIG. 8B . In this case the stack  48  of  FIG. 8B  may resist compression along its top edge and be more compressible along its lower edge, providing the outwardly-fanned shape shown in  FIG. 8B . 
     The gripping arms  74 ,  76  may apply a compressive force of between about one and about seven lbs, or less than about seven lbs, or less than about five lbs. As noted above, the greater thickness at the center of the envelopes  10  (or at the top of the envelopes, as per  FIG. 8B ) may limit the compression at the outer edges of the envelopes  10 . The arms  74 ,  76  may apply a compressive force to the stack of envelopes  48  such that portions of the envelopes that are not touching (i.e., the outer edges of the envelopes) are spaced apart by at least about 0.01 inches (or more particularly at least about 0.0105 inches), or at least about 0.02 inches. Thus, for example, the slots  80  in the envelope stack  48  may have a maximum width (i.e., at the location where envelopes  10  are spaced apart by their greatest distance) that is at least about 0.01 inches or at least about 0.02 inches, or less than about 0.01 inches or less than about 0.02 inches. In other words, the adjacent envelopes  10  may resist being interfacially pressed together too closely. Any of a wide variety of other mechanisms, devices or geometries, besides the gripping arms  74 ,  76 , may be utilized to compress the envelopes  10 . 
     When the envelopes  10  have their greatest thickness at their centers, as noted above, such a configuration can limit the compression of the envelope stack  48 . However, various envelopes can have various other configurations such that the greatest thickness of the envelopes is not necessarily at their centers, but could be at other locations. Accordingly, the arms  74 ,  76  may apply a compressive force to said stack of envelopes  48  such that the maximum space between adjacent envelopes is least about 0.01 inches, or at least about 0.0105 inches, or at least about 0.02 inches. The slots  80  in the envelope stack  48  may have maximum width of at least about 0.01 inches or at least about 0.02 inches, or less than about 0.01 inches or less than about 0.02 inches. 
     The gripping arms  74 ,  76  need not necessarily be located on the suction head  52 . For example, an alternate set of gripping arms (not shown) may be located on the table  34 . These table-mounted gripping arms may be able to be manipulated such that the stack  48  is located between the table-mounted gripping arms, over-compressed therebetween. The suction head  52  can then be lowered on top of or over the table-mounted gripping arms. The suction head  52  can include a lip or a set of stationary gripping arms that receive the over-compressed stack  48  therebetween. The table-mounted gripping arms may then be lowered or retracted away from the over-compressed stack to allow the stack  48  to expand slightly until the stack  48  engages the lip or set of stationary gripping arms of the suction head. In this manner the stack  48  is located in a compressed condition and coupled to the suction head  52 . 
     When the suction head  52  is lowered into the position shown in  FIGS. 7-10 , the suction cavity  60  lies on top of or adjacent to the top surface of the envelope stack  48 . In addition, the envelope moving apparatus  50  and/or suction head  52  may include a pair of rectractable or vertically movable guide plates  84  ( FIG. 7A ) that receive the envelope stack  48  therebetween to ensure proper alignment of the envelope stack  48  and/or suction head  52 . 
     The mouth  62  of the suction cavity  60  may be sized to match the size of the envelope stack  48  relatively closely. For example, in one embodiment the mouth  62  of the suction cavity  60  and/or the lip  70  is sized to generally match the size of the top surface of the envelope stack  48  such that the lip  70  engages the outer perimeter of the top surface of the envelope stack  48  (see, for example,  FIG. 9 ). In another embodiment, the mouth  62  of the suction cavity  60  and/or the lip  70  is spaced inwardly (or perhaps even outwardly) from the outer perimeter of the top surface of the envelope stack  48 . For example, in one case the mouth  62  has a length of about 90% of the length of the top surface of the envelope stack  48  and has a width of about 90% of the width of the top surface of the envelope stack  48 . However, the mouth  62  of the suction cavity  60  can have dimension as low as about 50% (or in some cases, even lower) of the respective length and width of the top surface of the envelope stack  48 . 
     The mouth  62  of the suction cavity  60  may have a surface area that is less than 100%, or less than about 90%, or less than about 80%, or less than about 70%, or less than about 60%, or less than about 50% of the surface area of the top surface of the envelope stack  48 . Alternately, the mouth  62  of the suction cavity  60  may have a surface area that is at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90%, or at least about 100% of the surface area of the envelope stack  48 . In one embodiment, the mouth  62  of the suction cavity  60  has a width of at least about 3 inches, or at least about 5 inches, or at least about 10 inches and a length of at least about 9 inches, or at least about 12 inches, or at least about 15 inches, or at least about 23 inches. The mouth  62  of the suction cavity  60  may have a surface area of at least about 36 square inches, or at least about 50 square inches, or at least about 100 square inches, or at least about 1000 square inches. The mouth  62  of the suction cavity  60  need not necessarily be rectangular, but instead can have a variety of other shapes. 
     In the position shown in  FIGS. 7-10  the suction cavity  60  lies on top of or adjacent to the top surface of the envelope stack  48 . In addition, the arms  74 ,  76  may be in their engaged position to grip and/or compress the envelope stack  48  therebetween. The suction source  66  is then activated to create suction in the suction cavity  60 . The suction in the suction cavity  60  helps to couple the envelope stack  48  to the suction head  52  and, in combination with the gripping arms  74 ,  76 , allows the suction head  52  to lift the envelope stack  48 . 
     The suction source  66  can be any of a variety of suction, vacuum or pump devices which form a vacuum or create suction or reduced pressure. However, in one embodiment the suction source  66  is a “scavenging” suction source which provides a relatively high volume, low pressure differential pressure flow of air. For example, the suction source  66  may provide a pressure differential of less than about 10 inches Hg, or less than about 20 inches Hg, or less than about 30 inches Hg. The suction source  66  may provide an air flow of at least about 30 static cubic feet per minute, or at least about 60 static cubic feet per minute, or at least about 100 static cubic feet per minute, or at least about 150 static cubic feet per minute. Such a suction flow can be provided by a variety of devices, for example by a PREVAC® rotary vacuum pump model SVB25ANN3F sold by Mechanical Ingenuity Corporation of Shrewsbury, N.J. 
     Due to inefficiencies in the system, the pressure and airflows in the suction chamber  60  will naturally be less than the pressure and airflow provided at the suction source  66 . Thus, during operation the suction chamber  60  may provide a pressure differential of less than about 5 inches Hg, or less than about 10 inches Hg, or less than about 20 inches Hg, or less than about 30 inches Hg, and may provide an air flow of at least about 25 static cubic feet per minute, or at least about 50 static cubic feet per minute, or at least about 60 static cubic feet per minute, or at least about 100 static cubic feet per minute, or at least about 150 static cubic feet per minute. 
     As best shown in  FIGS. 8A and 8B , because the envelope stack  48  is not a solid structure, and instead includes a plurality of slots  80  generally formed through its height, air flow flows between the slots  80  during suction, as shown by the arrows of  FIG. 8A . Thus a high flow rate is desired to properly secure the envelope stack  48  to the suction head  52 . In other words, a high differential pressure/low flow rate vacuum source may not be as effective as the low differential pressure/high flow rate suction source  66  because any attempt to create high pressure would be largely unsuccessful due to the “porous” nature of the envelope stack  48 . In contrast, a low differential pressure/high flow rate suction source is designed to pass large volumes of air therethrough, and therefore may be more suited to use with the porous envelope stack  48 . 
     When the suction device  66  is operated and creates a suction in the suction head  52 , and the gripping arms  74 ,  76  compress the envelope stack  48 , the envelope stack  48  is thereby secured to the suction head  52 . The suction head  52  can then lift the envelope stack  48  of off the table  34 , as shown in  FIG. 11 . The suction head  52 /envelope moving apparatus  50  can then be moved to carry the envelope stack  48  to the desired location. In one embodiment the suction head  52  is movable in two different linear directions such that the suction head  52  has two degrees of freedom (i.e. movable vertically and horizontally). However, if desired the suction head  52  can have one degree of freedom or more than two degrees of freedom, and may also be able to rotate along various axes. The suction head  52  may be movable in an automated manner, for example through the use of linear actuators, motors, pneumatically and the like. 
     The suction head  52 /envelope moving apparatus  50  may be manually movable. When the suction head  52 /envelope moving apparatus  50  is manually movable, a counterweight or mechanical assist may be provided to aid such manual movement. For example, the suction head  52 /envelope moving apparatus  50  may include a pneumatically counterbalanced mechanical assist, a counterweight, an electromechanical counterweight, or any combination of these devices. 
     As shown in  FIG. 10 , the lip  70  of the suction head  52  may be configured to rest upon or adjacent to the outer edges of the top surface of the envelope stack  48 . In addition, as described above, the bottom surface  71  of the lip  70  may have a minimum width C. This minimum width ensures a relatively good seal along surface  71  of the lip  70 . This seal ensures that the suction travels along the directions of the arrows of  FIG. 8  and solid line arrows of  FIG. 10 , and does not “short-circuit” along surface C (i.e., along the dotted line arrows of  FIG. 10 ). A lip  70  having a bottom surface  71  with a relatively short width may not provide a sufficient seal along surface C and therefore may provide inadequate sealing or suction forces to properly operate. 
     In the illustrated embodiment, once the envelope stack  48  is lifted, the suction head  52  and envelope moving apparatus  50  is positioned above a box or stacking tray  90 , as shown in  FIG. 12 . The suction head  52  then lowers the envelope stack  48  until it is located in the box/stacking tray  90 . The gripping arms  74 ,  76  are then moved to their release position and the suction in the suction cavity  60  is terminated or reduced until the envelope stack  48  is released on or in the stacking box/tray. The suction head  52  is then raised and positioned for subsequent lifting and moving operations. 
     The spiral wheels  32  may continue to rotate and deposit envelopes  10  on the table  34  during the lifting and moving operations of the suction head  52 . As shown in  FIG. 7 , the machine  30  may include a lead pin  77  which provides a backing surface which supports the next envelope stack. The lead pin  77  is coupled to a cylinder  79  such that the lead pin  77  can be retracted into the cylinder  79 . The lead pin  77  and cylinder  79  are movable in the downstream direction B as the next envelope stack  48  is created, and can be returned upstream to its position shown in  FIG. 7 . Thus, once the next envelope stack  48  is created the suction head  52  can lift and/or move the next envelope stack in the same manner outlined above. 
     The suction assist feature of the suction head  52  cooperates with the gripping arms  74 ,  76  to lift the envelope stack  48 . In this manner the suction head  52 /envelope moving apparatus  50  can lift significantly greater amounts of envelopes  10  than gripping arms  74 ,  76  can lift by themselves. Thus the suction head allows for much quicker and more efficient processing of envelopes  10  and envelope stacks  48 . 
     In addition the suction head  52  allows the envelope stack  48  to be lifted and placed into a container (i.e. a regular slotted container or “RSC”), rather than being pushed or slid into a container. This allows greater flexibility in packaging format, lowers material costs and provides greater flexibility in packaging formats. In addition, because the envelopes  10  are compressed by the suction head  52 /gripping arms  74 ,  76 , they can be packaged in a compressed manner which results in space savings and reduced material costs. 
     Having described the invention in detail and by reference to the various embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.