Patent Publication Number: US-7588247-B2

Title: Delivery device in sheet-fed offset rotary printing press

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a delivery device in a sheet-fed offset rotary printing press, which is arranged on the upstream sheet convey direction side of a pile board and comprises a suction unit for decreasing a sheet convey speed. 
     In a sheet-fed offset rotary printing press of this type, a sheet printed by a printing unit is conveyed as it is gripping-changed from the grippers of an impression cylinder to the grippers of delivery chains. After that, the sheet is released from the grippers at the convey terminal end and drops onto a pile board to be stacked there. Since the sheet conveyed by the delivery chains is gripped by the grippers only at its leading edge, the trailing edge of the sheet may flutter. Also, when the sheet is released to drop, an inertia occurs as the sheet travels, and the edge of the sheet may not be aligned when stacked. 
     In order to prevent this, a plurality of suction wheels line up below the sheet under conveyance on the upstream sheet convey direction side of the pile board in the widthwise direction of the sheet. The suction wheels have suction surfaces which draw the sheet by suction in slidable contact with it and rotate at a peripheral speed lower than the sheet convey speed. Thus, the traveling speed of the released sheet that has been gripped by the grippers is decreased. In double-sided printing, if the suction wheels described above are located within a pattern printed on the reverse surface of the sheet, the suction surfaces of the suction wheels damage the image portions printed on the sheet to degrade the printing quality. Hence, the suction wheels must be located in non-image portions which are not printed. 
     If non-image portions do not exist other than the two ends of the sheet in the widthwise direction or the number of non-image portions is small, the number of suction wheels is limited, and the center of the sheet becomes slack between the suction wheels, that is, so-called middle slack occurs. When such middle slack occurs, the two ends of the sheet may be disengaged from the suction wheels and are not drawn by them by suction, so the sheet convey speed cannot be sufficiently decreased. As a result, the sheet flutters. When the sheet is stacked, the edge of the sheet is not aligned well, and comes into contact with the brackets of the suction wheels to damage the printing surface. 
     In order to solve this, an apparatus is proposed as shown in Japanese Patent Laid-Open No. 2000-95409, which comprises a plurality of suction wheels which are arranged in the widthwise direction of a sheet to be conveyed, and at least a pair of nozzles which are arranged below the sheet on the two sides of the sheet to sandwich the center of the sheet in the widthwise direction. The pair of nozzles discharge air to blow upward the sheet under conveyance. In this apparatus, the air discharge directions from the nozzles are directed outwardly in the widthwise direction of the sheet to correct the middle slack, in which the sheet becomes slack downward, by an air layer formed by air from the nozzles. Thus, the two ends of the sheet are not disengaged from the suction wheels. 
     In the suction device of the conventional sheet-fed offset rotary printing press, air is blown to the sheet to pull the two ends of the sheet outwardly in the widthwise direction, thus stretching the sheet tightly. To lift the sheet not partially but entirely uniformly, the air blowing amount must be adjusted. It is, however, difficult to adjust the air blowing amount, and this adjustment takes time. In order to prevent middle slack of the sheet, nozzles must be provided in addition to the suction wheels. Accordingly, a hose which supplies discharge air to the nozzles is necessary in addition to a hose that supplies suction air to the suction wheels. This leads to a complicated structure and increases the manufacturing cost. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a delivery device in a sheet-fed offset rotary printing press, in which the air blowing amount need not be adjusted when preventing middle slack of a sheet to be delivered. 
     It is another object of the present invention to provide a delivery device in a sheet-fed offset rotary printing press, in which the structure is simplified to decrease the manufacturing cost. 
     In order to achieve the above objects, according to the present invention, there is provided a delivery device in a sheet-fed offset rotary printing press, comprising a plurality of suction units which are arranged above a pile board on an upstream sheet convey direction side below a sheet under conveyance in a widthwise direction of the sheet and which draw by suction the sheet under conveyance in slidable contact therewith, and at least one guide unit which is arranged between suction units among the plurality of suction units which are located at two ends and move the sheet at substantially the same speed as a convey speed of the sheet under conveyance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view schematically showing a delivery device in a sheet-fed offset rotary printing press according to the first embodiment of the present invention; 
         FIG. 2  is a plan view of the main part of the delivery device shown in  FIG. 1   
         FIG. 3  is a front view of the main part of the delivery device shown in  FIG. 1 ; 
         FIG. 4  is a sectional view taken along the line IV-IV of  FIG. 2 ; 
         FIG. 5  is a view seen from the arrow V of  FIG. 2 ; 
         FIG. 6  is a sectional view taken along the line VI-VI of  FIG. 5 ; 
         FIG. 7  is a view for explaining the looped state of a belt employed in the delivery device shown in  FIG. 1 ; 
         FIG. 8  is a sectional view showing a state wherein a guide unit employed in the delivery device shown in  FIG. 1  is mounted on a support member; 
         FIG. 9  is a sectional view taken along the line IX-IX of  FIG. 8 ; 
         FIG. 10  is a side view showing a state wherein the guide unit employed in the delivery device shown in  FIG. 1  is mounted on the support member; 
         FIG. 11  is a view for explaining switching between an air intake/exhaust source and a suction/discharge unit in the delivery device shown in  FIG. 1 ; 
         FIG. 12  is a side view showing the main part of a delivery device according to the second embodiment of the present invention; and 
         FIG. 13  is a sectional view taken along the line XIII-XIII of  FIG. 12 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A delivery device for a sheet-fed offset rotary printing press according to the first embodiment of the present invention will be described with reference to  FIGS. 1 to 11 . 
     Referring to  FIG. 1 , a delivery device  1  for a sheet-fed offset rotary printing press comprises a pair of delivery frames  2  which oppose each other at a predetermined gap. The delivery frames  2  axially support a pair of sprockets  3 . A pair of delivery chains  4  are looped between the pair of sprockets  3  of the delivery frames  2  and a pair of printing unit-side sprockets (not shown). A plurality of sets of gripper units  5  (schematically shown in  FIG. 1 ) comprising grippers and gripper pads line up on each of gripper bars supported between the pair of delivery chains  4  at predetermined intervals. After printing, a sheet  6  which is gripped by the gripper units  5  and conveyed as the delivery chains  4  travel is released from the gripper units  5  and drops on the upstream sheet convey direction side of the sprockets  3 . 
     A pile board  7  with four corners suspended by four elevating chains  8  moves vertically when a motor (not shown) rotates clockwise/counterclockwise. A flat rectangular parallelepiped pallet  9  having a hole where the forks of a fork lift or the like can be inserted is placed on the pile board  7 . On the upstream sheet convey direction (a direction of an arrow B) side of the pile board  7 , five suction units  10 A to  10 E comprising belt type suction wheels arranged below the sheet  6  under conveyance line up in the widthwise direction (directions of arrows C and D) of the sheet  6  under conveyance, i.e., in a direction perpendicular to the convey direction (directions of an arrow A and the arrow B) of the sheet  6 , as shown in  FIG. 3 . A sheet lay  11  abuts against the leading edge of the dropping sheet  6  to align it. 
     As shown in  FIG. 2 , a pair of subframes  13 A and  13 B are arranged to oppose each other at a predetermined gap in the directions of the arrows C and D, and two stays  14  and  15  horizontally extend between the subframes  13 A and  13 B. A driving shaft  16  is rotatably supported between the subframes  13 A and  13 B and rotatably driven by a motor  16   a  (first driving source). One subframe  13 B and a support stay  18  which is attached between the stays  14  and  15  rotatably support screw shafts  17 A and  17 B. The screw shafts  17 A and  17 B extend toward the other subframe  13 A with their axial movement being regulated. When the projecting portions of the screw shafts  17 A and  17 B through the subframe  13 B are manually rotated clockwise and counterclockwise, the suction units  10 A,  10 B,  10 D, and  10 E and discharge units  80 A and  80 C (to be described later) move in the directions of the arrows C and D. 
     The screw shafts  17 A and  17 B which support support members  25 A,  25 B,  25 D, and  25 E to be movable in the sheet widthwise direction are longitudinal feed inverse helical screws and each have a screw pitch that is larger on the outer side than on the inner side. A support member  25 C which is located at the center has no threaded portion and does not move accordingly. Hence, the gap between a discharge unit  80  and suction unit  10  in the widthwise direction of the sheet  6  under conveyance is adjusted in accordance with the size of the sheet  6 . 
     A rotating shaft  19  is rotatably supported between the pair of subframes  13 A and  13 B. When a motor (not shown) rotatably drives the rotating shaft  19  clockwise/counterclockwise, the subframes  13 A and  13 B move in the directions of the arrows A and B with respect to the pair of delivery frames  2  through pinions  20  and racks (not shown) axially mounted on the two ends of the rotating shaft  19 . A sheet lay  21  which abuts against the trailing edge of the sheet  6  dropping onto the pile board  7  to align it has a large number of air vent holes  21   a  and is attached to the stay  14  to extend in the directions of the arrows C and D. 
     As shown in  FIG. 3 , blocks  22   a  each having one end supported by the stay  14  about a corresponding small shaft  23  as the swing center swingably support corresponding detection pieces  22  which detect the upward movement limit of the pile board  7 . When the pallet  9  of the pile board  7  that has moved upward abuts against the detection pieces  22 , the detection pieces  22  detect the pallet  9  to stop upward movement of the pile board  7 . This prevents the pallet  9  from pushing up the suction units  10  or the like. 
     The suction units  10 A to  10 E and the support members  25 A to  25 E which support them will be described with reference to  FIGS. 4 to 6 . The suction units  10 A to  10 E and the support members  25 A to  25 E have the same basic structure. Hence, only the suction unit  10 E and support member  25 E will be described hereinafter, and the remaining suction units  10 A to  10 D and support members  25 A to  25 D will be described when necessary. 
     As shown in  FIG. 4 , the stays  14  and  15  support the flat block-like support member  25 E to be movable in the widthwise direction (the directions of the arrows C and D) of the sheet  6  under conveyance. A screw hole  28  is threadably formed in an inclined upper mount surface  27  of the support member  25 E. A flat block-like support target member  26 E which forms the suction unit  10 E is mounted on the inclined upper mount surface  27  of the support member  25 E. The support target member  26 E has a vertically extending insertion hole  29 . A lower surface  30  of the support target member  26 E is brought into contact with the mount surface  27  of the support member  25 E. After that, a bolt  31  (engaging member) inserted in the insertion hole  29  is threadably engaged in the screw hole  28  (engaging target portion) to mount the support target member  26 E on the support member  25 E. 
     As shown in  FIG. 6 , the support member  25 E has a large-diameter through hole  32  and two small-diameter through holes  33  (one through hole  33  is not shown). The diameter of the through hole  32  is larger than the diameter of the driving shaft  16  and incorporates a bearing  34 . A sleeve  35  is fitted on the driving shaft  16 . The sleeve  35  is rotatably supported in the through hole  32  of the support member  25 E through the bearing  34 . Fastening a set screw  36  allows to rotate the sleeve  35  together with the driving shaft  16 . A ring-like slide member  38 A fitted on the driving shaft  16  and one end face of the sleeve  35  sandwich a driving gear  37 . The driving gear  37  is mounted on one end face of the sleeve  35  with bolts. 
     A coming-out preventive member  40  is mounted on the other end of the sleeve  35  with a set screw. The coming-out preventive member  40  and a step  35   a  formed on the sleeve  35  sandwich the support member  25 E. Thus, when the support member  25 E moves in the directions of the arrows C and D, the sleeve  35  moves together with the support member  25 E. A slide member  38 B fitted on the driving shaft  16  is mounted on the outer surface of the coming-out preventive member  40 . 
     A substantially cylindrical moving element  42  having a threaded portion  42   a  to threadably engage with the screw shaft  17 B is fitted in the through hole  33  of the support member  25 E. A ring member  43  axially mounted on one end of the moving element  42  and a step  42   b  of the moving element  42  sandwich the support member  25 E. When the moving element  42  moves in the directions of the arrows C and D, the support member  25 E also moves together with the moving element  42  in the directions of the arrows C and D. As shown in  FIG. 5 , a moving element  44  having the same function as that of the moving element  42  threadably engages with the other screw shaft  17 A. When the screw shafts  17 A and  17 B are rotated, the support member  25 E moves together with the screw shafts  17 A and  17 B in the directions of the arrows C and D through the moving elements  42  and  44 . As shown in  FIG. 4 , the support member  25 E has an air passage  45  which extends between an upper end opening  45   a  in its upper surface and a lower end opening  45   b  in its side surface. A hose joint  46  is attached to the lower end opening  45   b.    
     As shown in  FIG. 6 , a large-diameter pulley  52  is rotatably supported by a shaft  50 , which extends upright on a support target member  26 , through a bearing  51 . A gear  54  is rotatably supported at the distal end of the shaft  50  through a bearing  53 . The gear  54  is mounted on the upper end face of the large-diameter pulley  52  through bolts. A bolt  56  which threadably engages with the shaft  50  through a washer  55  regulates the gear  54  from coming out from the large-diameter pulley  52  and shaft  50 . 
     As shown in  FIG. 5 , small-diameter pulleys  62  and  63  are rotatably supported by shafts  60  and  61 , which extend upright in the upper portion of the support target member  26 , through bearings. Coming-out preventive members  64  and  65  regulate the small-diameter pulleys  62  and  63  from coming out from the shafts  60  and  61 . A suction belt  66  having a large number of suction ports  66   a  in its outer surface is looped among the small-diameter pulleys  62  and  63  and large-diameter pulley  52  to form a triangle. 
     As shown in  FIG. 5 , an air duct  67  is arranged between the small-diameter pulleys  62  and  63  to oppose the inner side of the suction belt  66 . The air duct  67  has a U-shaped section such that its upper portion that opposes the suction belt  66  is open. When suction air from an intake source  101  (to be described later) is supplied to the air duct  67 , that portion  66   b  of the suction belt  66  which opposes the air duct  67  forms a suction surface which draws by suction the sheet  6  under conveyance in slidable contact with it. An air passage  68  is formed under the air duct  67 . The air passage  68  vertically extends through the support target member  26  so an upper end opening  68   a  and lower end opening  68   b  communicate with each other. The upper end opening  68   a  of the air passage  68  is connected to a communication hole  67   a  formed in the bottom of the air duct  67 . 
     As described above, when the support target member  26 E is mounted on the support member  25 E, the upper end opening  45   a  of the air passage  45  comes into contact with the lower end opening  68   b  of the air passage  68 , so the air passage  45  of the support member  25 E communicates with the air passage  68  of the support target member  26 E, as shown in  FIG. 4 . Simultaneously, the driving gear  37  of the support member  25 E meshes with the gear  54  of the support target member  26 E. 
     A belt  70  which guides the sheet  6  gripped and conveyed by the grippers  5  is arranged below the delivery chains  4 . As shown in  FIG. 7 , the belt  70  is looped among a driving roller  72 , a tension roller  73 , and driven rollers  71 ,  74 ,  75 , and  76 . In a sheet guide region between the driven rollers  71  and  76 , the belt  70  is supported parallel to the delivery chains  4  and driven by a motor  77  (second driving source) which guides the driving roller  72  to travel at the same traveling speed as that of the delivery chains  4  through a reduction gear (not shown). 
     The guide unit will be described with reference to  FIGS. 8 to 9 . As shown in  FIG. 9 , a guide unit  80  comprises a block-like base  81  to be mounted on a support member  25 , a pair of air blowing hollow bodies  82 A and  82 B to be mounted on the base  81 , guide members  83 A and  83 B to be rotatably guided by the air blowing hollow bodies  82 A and  82 B, respectively, and a pair of rotation transmission bodies  84  which transmit rotation to the guide members  83 A and  83 B, respectively. 
     As shown in  FIG. 8 , the base  81  comprises an insertion hole  86  through which the bolt  31  is to be inserted, an air passage  87  having a lower end opening  87   a,  and a through hole  88  which communicates with the air passage  87  and extends through the base  81  in the sheet widthwise direction. After the lower surface of the base  81  is brought into contact with a mount surface  27  of the support member  25 , the bolt  31  inserted in the insertion hole  86  is threadably engaged in the screw hole  28  of the support member  25  to mount the base  81  on the support member  25 . When the base  81  is mounted on the support member  25 , the lower end opening  87   a  of the air passage  87  comes into contact with the upper end opening  45   a  of the air passage  45 , so the air passage  87  communicates with the air passage  45 . 
     As shown in  FIG. 9 , each of the air blowing hollow bodies  82 A and  82 B substantially forms a bottomed cylinder having a hollow portion  82   a  with one open end, and has a thick-walled projecting portion  82   b  at its other end. Two communication holes  82   c  which connect the hollow portion  82   a  to the outside are formed in the upper portion of the projecting portion  82   b.  The air blowing hollow body  82 B has, in part of its outer surface, a communication window  82   d  through which the hollow portion  82   a  communicates with the air passage  87  of the base  81 . The air blowing hollow bodies  82 A and  82 B are mounted to be fitted in the through hole  88  of the base  81 . At this time, the air blowing hollow body  82 B is mounted such that the communication window  82   d  communicates with the air passage  87  of the base  81 . The air blowing hollow body  82 A is mounted such that its open end is in contact with that of the air blowing hollow body  82 B. At this time, the hollow portion  82   a  of each of the air blowing hollow bodies  82 A and  82 B which communicate with each other is connected to the air passage  87  of the base  81  and the air passage  45  of the support member  25  through the communication window  82   d.    
     Each of the cylindrical guide members  83 A and  83 B is supported at the other end of the corresponding one of the air blowing hollow bodies  82 A and  82 B to be rotatable about the corresponding projecting portion  82   b  through a bearing  90 . The guide members  83 A and  83 B have a large number of small-diameter discharge ports  83   a  which extend from inside to the outside. Air from an air supply source  102  (to be described air) is discharged through, of the large number of discharge ports  83   a,  those which oppose the communication holes  82   c  of the air blowing hollow bodies  82 A and  82 B. 
     One end of each of a pair of levers  92  is axially mounted on the corresponding one of the air blowing hollow bodies  82 A and  82 B, and each of a pair of shafts  93  is axially mounted on the other end of the corresponding lever  92 . The rotation transmission bodies  84  are rotatably supported on the shafts  93  through bearings  94 . Rubber-made contact portions  84   a  which come into contact with the guide members  83 A and  83 B are mounted on the outer surfaces the rotation transmission bodies  84 , respectively. As shown in  FIG. 10 , the contact portions  84   a  also come into contact with the belt  70 . Through frictional contact with the rotation transmission bodies  84 , the guide members  83 A and  83 B rotate at the same peripheral speed as the traveling speed of the belt  70  in the same direction (counterclockwise in  FIG. 10 ) as the sheet convey direction. The guide members  83 A and  83 B are arranged at positions slightly lower than the suction belt  66  of a suction unit  10 . 
     Five air supply devices  100 A to  100 E shown in  FIG. 11  supply discharge air or suction air to the respective support members  25 A to  25 E. The air supply devices  100 A to  100 E share the one air intake source  101  which supplies suction air to the suction units  10 A to  10 E through the respective support members  25 A to  25 E. The air supply devices  100 A to  100 E also share one air exhaust source  102  which supplies discharge air to the air blowing boxes  80 A to  80 C through the support members  25 A to  25 E. The air intake source  101  and air exhaust source  102  are shared by the air supply devices  100 A to  100 E. 
     The air intake source  101  and air exhaust source  102  are connected to the air supply devices  100 A to  100 E through a switching device  103 . The switching device  103  comprises an air intake passage  105  which is connected to the intake source  101  through a hose  104 , an air blowing passage  107  which is connected to the air exhaust source  102  through a hose  106 , an air supply passage  109  which is connected to the hose joint  46  through a common hose  108 , and a switching valve  110  which selectively changes over the air passage  109  between the air passages  105  and  107 . 
     The switching valve  110  has a notch  110   a  with a semilunar section. When the notch  110   a  is at the position indicated by an alternate long and two short dashed line in  FIG. 10 , the air passage  105  and air passage  109  communicate with each other through the notch  110   a.  When the notch  110   a  is at a position indicated by a solid line where it has been pivoted from the position indicated by the alternate long and two short dashed line by substantially 90°, the air passage  107  and air passage  109  communicate with each other through the notch  110   a.  An L-shaped lever  111  is swingably supported at its center about a shaft  112  extending upright from an apparatus fixing portion as the swing center. A manipulation lever  113  is attached to one end of the lever  111 , and one end of a connection bar  114  is pivotally mounted on the other end of the lever  111 . A switching bar  115  is provided to the switching valve  110 . The distal end of the switching bar  115  is pivotally mounted on the other end of the connection bar  114 . 
     Delivery operation in the delivery device having the above arrangement will be described. First, a case will be described when the convey speed of the sheet delivered by the suction units  10 A to  10 E is to be decreased. In this case, the support target members  26  are mounted on the mount surfaces  27  of the support members  25 A to  25 E of all the suction units  10 A to  10 E with the bolts  31 , as shown in  FIG. 4 . In this state, the manipulation levers  113  of all the air supply devices  100 A to  100 E are pivoted counterclockwise, as indicated by the alternate long and two short dashed line in  FIG. 11 , to allow the air passages  105  and air passages  109  to communicate with each other. 
     Thus, suction air is supplied to the air passages  45  of the support members  25 A to  25 E of all the suction units  10 A to  10 E, and to the air passages  68  of support target members  26 A to  26 D and of the support target member  26 E which communicate with the corresponding air passages  45 . The suction air supplied to the air passages  68  is then supplied to the air ducts  67 , so the sheet  6  under conveyance is drawn by suction by the suction surfaces  66   b  of the suction belts  66  which oppose the air ducts  67 . 
     Referring to  FIG. 6 , when the motor  16   a  is driven to rotate the driving shaft  16 , the sleeves  35  of the support members  25 A to  25 E rotate. As the sleeves  35  rotate, the driving gears  37  rotate together with them to rotate the gears  54  of the support target members  26 A to  26 E meshing with the driving gears  37 . Thus, the large-diameter pulleys  52  rotate together with the gears  54 , so the suction belts  66  looped among the corresponding large-diameter pulleys  52  and small-diameter pulleys  62  and  63  travel in the direction of the arrow A at a speed slightly lower than the convey speed of the sheet  6 . At this time, the belts  70  ( FIG. 5 ) are driven by motors (not shown) to travel in the direction of the arrow A at substantially the same speed as the traveling speed of the delivery chains  4 . 
     The sheet  6  which is released from the gripper units  5  to drop at the convey terminal end of the delivery device  1  is drawn by suction at its trailing edge by the suction surfaces  66   b  of the five suction belts  66  to be in slidable contact with them. Thus, the traveling speed of the sheet  6  is decreased, so the sheet  6  is stacked on the pallet  9  on the pile board  7 . 
     Assume that the delivery device is to be shifted from single-sided printing to double-sided, and the number of non-image portions is limited and non-image portions are not provided at the center in the widthwise direction of the sheet  6 . In such a case, the three suction units  10 B,  10 C, and  10 D cannot be arranged to be located at the center in the widthwise direction of the sheet  6  under conveyance. In this case, the three guide units  80  are provided in place of the suction units  10 B,  10 C, and  10 D. 
     First, the bolts  31  that mount the support target members  26 B,  26 C, and  26 D are loosened, and the suction units  10 B,  10 C, and  10 D are removed together with the support target members  26 B,  26 C, and  26 D from the support members  25 B,  25 C, and  25 D. Subsequently, the guide units  80  are respectively mounted on the support members  25 B,  25 C, and  25 D with the bolts  31 . 
     In this state, the manipulation levers  113  of the air supply devices  100 A and  100 E are pivoted counterclockwise, as indicated by the alternate long and two short dashed line in  FIG. 11 , to allow the air intake passages  105  and air supply passages  109  to communicate with each other. Thus, suction air is supplied to the suction units  10 A and  10 E to supply the suction air to the suction belts  66  of the suction units  10 A and  10 E, respectively. Simultaneously, the manipulation levers  113  of the air supply devices  100 B,  100 C, and  100 D are pivoted clockwise as indicated by the solid line in  FIG. 11 , to allow the air passages  107  and air passages  109  to communicate with each other. 
     Thus, discharge air is supplied to the air passages  45  of the support members  25 B,  25 C, and  25 D, and to the air passages  87  of the guide units  80  that communicate with the air passages  45 . The discharge air supplied to the respective air passages  87  is discharged from the discharge ports  83   a  of the guide members  83 A and  83 B included in the guide unit  80 . When the motor  16   a  is driven to rotate the driving shaft  16 , the suction belts  66  of the suction units  10 A and  10 E mounted on the support members  25 A and  25 E travel in the direction of the arrow A at a speed slightly lower than the convey speed of the sheet  6 . 
     When delivery operation is performed in this state, the guide members  83 A and  83 B of each of the three guide units  80 , which are arranged under the sheet  6  released from the gripper units  5  to drop at the convey terminal end of the delivery device  1 , support and guide a sheet in the widthwise direction of the sheet. This prevents middle slack of the sheet  6 , and the two ends of the sheet  6  will not disengage from the suction belts  66  of the suction units  10 A and  10 E, so that the convey speed of the sheet  6  can be decreased sufficiently. As a result, fluttering of the sheet  6  is prevented reliably, and misalignment of the edge of the sheet when stacked can be prevented, and the sheet can be prevented from coming into contact with the brackets of the suction wheels, so its printing surface will not be damaged. As the guide members  83 A and  83 B which guide the sheet  6  rotate at substantially the same speed as the convey speed of the sheet  6  in the same direction as the convey direction of the sheet  6 , the guide members  83 A and  83 B will not damage the printing surface. 
     Air is discharged from the discharge ports  83   a  of the guide members  83 A and  83 B through the air passages  45  and  87  and the air blowing hollow bodies  82 A and  82 B toward the lower surface of the sheet  6  under conveyance to float the sheet  6 . Thus, middle slack of the sheet  6  can be prevented reliably. The sheet  6  which is released from the gripper units  5  to drop at the convey terminal end of the delivery device  1  is drawn by suction at its trailing edge by the suction surfaces  66   b  of the suction units  10 A to  10 E to be in slidable contact with them. Thus, the traveling speed of the sheet  6  is decreased, so the sheet  6  is reliably stacked on the pallet  9  on the pile board  7 . 
     As described above, the suction units  10 B to  10 D and guide units  80  can be selectively mounted on the support members  25 B to  25 D. No guide unit  80  need be provided in advance independently of the suction units, thus simplifying the structure. Both the mounting structures of the suction units  10 B to  10 D with respect to the support members  25 B to  25 D and the mounting structures of the guide units  80  with respect to the support members  25 B to  25 D employ the bolts  31 . Thus, two types of mounting structures are not needed, so the structure can be simplified and the number of components can be decreased. The switching device  103  is provided which switches air supply from the air intake source  101 /air exhaust source  102  to the suction unit  10 /discharge unit  80 . Thus, air can be supplied to the suction unit  10  and discharge unit  80  with the common hose  108 , so the structure can be simplified and the number of components can be decreased. 
     The second embodiment of the present invention will be described with reference to  FIGS. 12 and 13 . As shown in  FIG. 13 , shafts  124  and  125  horizontally extend between a pair of side plates  121  and  122  standing upright on a bottom plate  123  to oppose each other. A guide member  127  is rotatably supported by the shaft  124  through bearings  126 , and a rotation transmission body  129  is rotatably supported by the shaft  125  through bearings  128 . A rubber-made contact portion  129   a  which comes into contact with the guide member  127  is mounted on the outer surface of the rotation transmission body  129 . 
     As shown in  FIG. 12 , a holding block  130  having an L-shaped section is mounted on the bottom plate  123  with a bolt  131 . A groove  130   a  is formed between the bottom plate  123  and holding block  130 . A screw hole  130   b  communicating with the groove  130   a  which engages with a stay  14  is formed in the bottom of the bottom plate  123 . After the groove  130   a  is fitted with the stay  14  between support members  25 A and  25 E, the distal end of a bolt  132  threadably engaging in the screw hole  130   b  is abutted against the stay  14  to mount the bottom plate  123  on the stay  14 . Thus, one or more guide members  125  are positioned between suction units  10 A and  10 E at the two ends independently of support members  25 B,  25 C, and  25 D, and arranged below suction belts  66 , as shown in  FIG. 12 . At this time, the contact portion  129   a  of the rotation transmission body  129  comes into contact with a belt  70 . 
     In this arrangement, suction units  10 B,  10 C, and  10 D other than the suction units  10 A and  10 E at the two ends are removed from the support members  25 B,  25 C, and  25 D, respectively. Subsequently, suction air is supplied to the suction units  10 A and  10 E supported by the support members  25 A and  25 E, respectively, and a motor  16   a  drives the suction belts  66  of the suction units  10 A and  10 E to travel at a speed slightly lower than the convey speed of a sheet  6 . In this state, when the sheet  6  is released from grippers  5  at the convey terminal end of a delivery device  1  to drop, the sheet  6  is guided in the sheet convey direction as its central portion is supported by the guide member  127  arranged below the sheet  6 . This can prevent middle slack of the sheet  6 . 
     According to this embodiment, as the two ends of the sheet  6  will not disengage from the suction belts  66  of the suction units  10 A and  10 E, the convey speed of the sheet  6  can decrease sufficiently. Thus, the sheet  6  will not flutter, so misalignment of the edge of the sheet when stacked can be prevented, and the sheet can be prevented from coming into contact with the brackets of the suction units, so its printing surface will not be damaged. As the guide member  127  which guides the sheet  6  rotates at substantially the same speed as the convey speed of the sheet  6  in the same direction as the convey direction of the sheet  6 , the guide member  127  will not damage the printing surface. The guide member  127  can be moved and adjusted in directions of arrows C and D by loosening the bolt  132  and moving the holding block  130  in the longitudinal direction of the stay  14 . Two or more guide members  127  can be provided when necessary. 
     In the first embodiment described above, air is discharged from the guide members  83 A and  83 B. If the sheet  6  need not be suspended from the guide members  83 A and  83 B, air discharge is unnecessary. The sheet suffices as far as it is a sheet-type object. 
     As has been described above, according to the present invention, since the guide member which guides at substantially the same speed as the convey speed of the sheet under conveyance is provided, middle slack of the sheet can be prevented without damaging the sheet. As air need not be blown to the sheet, the air blowing amount need not be adjusted. 
     The suction units and discharge units can be selectively mounted on the support members. Thus, no discharge units need be provided in advance independently of the suction units, so the structure can be simplified. Since the sheet is suspended from the guide member by air discharged from the discharge units, middle slack of the sheet can be prevented reliably. 
     As air can be supplied to the suction units and discharge units through common pipes, the structure can be simplified and the manufacturing cost can decrease.