Patent Publication Number: US-8122692-B2

Title: Empty bag supply method and empty bag supply apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to improvements in an empty bag supply method and empty bag supply apparatus in which an uppermost bag of a group of bags stacked in a conveyor magazine is sequentially taken out and transported along a predetermined bag transportation path, so that the bag is finally transferred to, for instance, a gripper of a bag packaging apparatus. 
     2. Description of the Related Art 
     Japanese Utility Model Registration No. 2603966 discloses a conveyor magazine; and in this conveyer magazine, a belt conveyor conveys a group of empty bags stacked in such a format that the bag mouths are facing forward and the upper bags shifted forward, and a fast-feed belt separates the uppermost empty bag from the group of empty bags on the belt conveyor and feeds it out forward. A toothed wheel is provided on the belt conveyor at the forward side of the fast-feed belt so that it feeds out forward the empty bag separated by the fast-feed belt, and further a positioning stopper is provided so that the tip end of the bag mouth of the empty bag fed by the toothed wheel comes into contact with it and the bag is thus positioned by this positioning stopper by the bag mouth. The empty bag positioned by the stopper in the conveyor magazine is changed from a roughly horizontal attitude to a substantially vertical attitude with the bag mouth facing upward and then supplied to a neighboring bag packaging apparatus. 
     In this type of a conveyor magazine-style bag supply apparatus, when supplying zipper-equipped bags or spout-equipped bags, problems would occur. More specifically, when an empty bag that is equipped with additional elements (for instance, a zipper, a spout or the like) that has certain thickness near the bag mouth is supplied, though an empty bag below the uppermost empty bag (next lower empty bags) is fast-fed by the fast-feed belt, the next empty bag may be impeded from being fed forward beyond the toothed wheel. This is because when the toothed wheel descends and contacts the uppermost empty bag, pressure is applied to the next lower empty bag through the uppermost empty bag, and as a result, the zipper, spout or other part of the next lower empty bag is caught on the toothed wheel, so that the forward movement of the bag is impeded. When this occurs, the next lower empty bag bends upward; and though the bag eventually returns to its original flat state when the toothed wheel ascends and the toothed wheel pressure is released, the bending and returning phenomenon can create irregular fetches and inappropriate positioning of the uppermost empty bag. 
     In the conveyor magazines disclosed in Japanese Patent Application Laid-Open (Kokai) Nos. 2006-123910 and 2006-143264, a bag is transported with its bottom facing in the bag feeding direction, so that the tip end of the bag bottom comes into contact with a stopper and the empty bag is thus positioned by the stopper (positioning by the bag bottom). Though this would resolve the above-described problem that would occur when positioning is made by the bag mouth as seen in Japanese Utility Model Registration No. 2603966 (in which next lower empty bags bend and return, creating inappropriate fetch or inappropriate positioning of the uppermost empty bag), it creates new problems as noted below even when the bag bottom faces in the bag feeding direction, since ultimately the empty bag must be supplied to the gripper of a bag packaging apparatus with the bag mouth facing upward. 
     (1) Because the empty bag is positioned by the bag bottom, whenever the bag surface of the empty bag is distorted in a wave shape in the direction of the length, the position of the bag mouth of the empty bag will not be consistent. As a result, in Japanese Patent Application Laid-Open (Kokai) No. 2006-123910, the suction position of a vacuum cup 17 tends to shift in the direction of the length of the empty bag, and in Japanese Patent Application Laid-Open (Kokai) No. 2006-143264, the gripping position of the gripping claw 41 will shift in the direction of the length of the empty bag; as a result, the empty bag&#39;s height (height position of bag mouth) when the empty bag is transferred to the bag packaging apparatus gripper will not be adequate. This creates a problem that the gripping position of the gripper becomes different in the direction of length for each empty bag. 
     (2) When empty bags supplied to the bag packaging apparatus are changed to those which are of different length dimensions, stopper adjustment is not required when positioning of the bag is made by the bag mouth as in Japanese Utility Model Registration No. 2603966; however, in Japanese Patent Application Laid-Open (Kokai) No. 2006-123910, the location of the stopper (12) needs to be changed; and in Japanese Patent Application Laid-Open (Kokai) No. 2006-143264, the location of the stopper (32) needs to be changed. Since the adjustment precision of the stoppers directly affects the precision of where the empty bag is supplied to grippers, adjustment work must be made extremely carefully, and thus it creates a major burden on the operator. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is to solve the problems described above that occur when a group of empty bags is stacked within a conveyor magazine, transferred in a bag feeding direction with bag bottom facing forward, and the uppermost empty bag in the stacked group of empty bags is taken out sequentially from the conveyor magazine, so that the empty bag is transported along a predetermined bag transportation path and then transferred to a gripper of a bag packaging apparatus. 
     It is, therefore, an object of the present invention to provide an empty bag supply method and apparatus wherein the height of an empty bag when the bag is transferred to a gripper of a bag packaging apparatus is constantly kept at adequate height so that the position where the gripper grips the bag mouth of the empty bag is kept unchanged. 
     It is another object of the present invention to provide an empty bag supply method and apparatus that facilitates stopper adjustment work when working on empty bags of different length dimensions. 
     The above objects are accomplished by unique steps of the present invention for an empty bag supply method that
         separates and feeds out an empty bag that is uppermost of a group of empty bags stacked on a conveyor in such a format that bag bottoms of the empty bags face forward and upper bags are shifted forward,   feeds the empty bag forward so that the empty bag comes into contact with a first positioning stopper thus being positioned by a bag bottom thereof, then   transports the empty bag along a predetermined bag transportation path, and then   transfers the empty bag to a gripper of a bag packaging apparatus; and       

     in the present invention, the empty bag supply method is characterized in that the method comprises the steps of:
         changing the attitude of the empty bag being positioned by the bag bottom, so that the empty bag is brought substantially vertical with the bag bottom facing upward,   transporting the empty bag with its bag mouth facing forward and bringing the bag mouth into contact with a second positioning stopper, thus positioning the empty bag by the bag mouth,   changing the attitude of the empty bag being positioned by the bag mouth, so that the empty bag takes a substantially vertical attitude with the bag mouth facing upward, and   transferring the empty bag to the gripper of the bag packaging apparatus.       

     More specifically, in the present invention,
         a first suction member suctions the top surface of the empty bag being positioned at a bag bottom thereof,   the first suction member lifts up the empty bag to a first transfer position,   a first transporting member holds the empty bag moved to the first transfer position,   the first transporting member transports the empty bag to a second transfer position and changes the attitude of the empty bag so that the empty bag takes a substantially vertical attitude with the bag bottom facing upward,   a second suction member suctions the front surface of the empty bag which is substantially in a vertical attitude,   the second suction member transports the empty bag, with a bag mouth thereof facing forward, to a third transfer position which is on a positioning conveyor or on a positioning chute,   the bag mouth of the empty bag is brought into contact with a second positioning stopper on the positioning conveyor or on the positioning chute so that the empty bag is positioned by the bag mouth,   a third suction member suctions the top surface of the empty bag being positioned by the bag mouth,   the third suction member lifts up the empty bag to a fourth transfer position,   a second transporting member holds the empty bag moved to the fourth transfer position,   the second transporting member transports the empty bag to a fifth transfer position and changes the attitude of the empty bag so that the empty bag takes a substantially vertical attitude with the bag mouth facing upward, and then   the empty bag is transferred to the gripper of the bag packaging apparatus.       

     Furthermore, the above objects are accomplished by a unique structure of the present invention for an empty bag supply apparatus that includes a conveyor magazine provided with:
         a belt conveyor for conveying a group of empty bags stacked in such a format that bag bottoms of the empty bags face forward and upper bags are shifted forward,   a fast-feed belt for separating an uppermost empty bag from the group of empty bags on the belt conveyor and feeding out the empty bag forward,   a toothed wheel provided on a forward side of the fast-feed belt on the belt conveyor so as to feed out the empty bag separated by the fast-feed belt forward, and   a first positioning stopper with which a bottom end of the empty bag fed out by the toothed wheel comes into contact,       

     so that the empty bag supply apparatus transports the empty bag positioned by contacting the first positioning stopper along a predetermined bag transportation path and transfers the empty bag to a gripper of a bag packaging apparatus; and 
     in the present invention, it is characterized in that the empty bag supply apparatus further includes:
         a first suction member that suctions the top surface of the empty bag being positioned by the first positioning stopper and lifts up the empty bag to a first transfer position,   a first transporting member that receives from the first suction member the empty bag moved to the first transfer position and transports the empty bag to a second transfer position so that the empty bag takes a substantially vertical attitude with its bag bottom facing upward,   a second suction member that suctions the front surface of the empty bag of substantially vertical attitude and transports the empty bag to a third transfer position with its bag mouth facing forward,   a positioning conveyor or positioning chute that at the third transfer position receives the empty bag being suctioned by the second suction member and transports the empty bag forward, the positioning conveyor or positioning chute being provided with a second positioning stopper with which the tip end of the bag mouth of the empty bag comes into contact,   a third suction member that suctions the top surface of the empty bag, which is in contact with the second positioning stopper and thereby being positioned, and lifts up the empty bag to a fourth transfer position, and   a second transporting member that receives from the third suction member the empty bag moved to the fourth transfer position and transports the empty bag to a fifth transfer position so that the empty bag takes a substantially vertical attitude with the bag mouth facing upward; and   at the fifth transfer position the empty bag supply apparatus transfers the empty bag to a gripper of a bag packaging apparatus.       

     The above-described empty bag supply apparatus of the present invention can take the following specific structures:
         (1) The positioning conveyor or positioning chute is provided with a lifting member that raises the underside of the empty bag which is in contact by the bag mouth with the second positioning stopper, thus creating a space between the empty bag and the supporting surface of the positioning conveyor or positioning chute so that a next empty bag can enter the space. With this structure, a next empty bag can be fed in while the previous empty bag is still on the positioning conveyor or positioning chute, thus increasing the processing capability.   (2) The positioning conveyor or positioning chute can be provided with a lifting member that projects up from below through the conveyance surface so that the lifting member, when projected out above the conveyance surface, raises the underside of the empty bag which is in contact by the bag mouth with the second positioning stopper, thus creating a space between the empty bag and the conveyance surface so that a next empty bag can enter the space. With this structure, a next empty bag fed in can be stopped by the lifting member and is not fed all the way to the second positioning stopper. As a result, the third suction member is prevented from taking two bags together.   (3) The empty bag supply apparatus can be further provided with a suction assistance plate which is provided near the second transfer position and moves back and forth between a retreated position that avoids interference with an empty bag being transported to the second transfer position and a suction assistance position that faces the suction surface of the second suction member which suctions the front surface of the empty bag which is in a substantially vertical attitude at the second transfer position. This suction assistance plate supports the rear surface of the empty bag at the suction assistance position so as to assist the second suction member to suction the empty bag.   (4) The first transporting member can be comprised of a pair of gripping members that grip both side edges of the empty bag. This structure having two separated gripping members makes it easy to prevent interference with the first suction member.   (5) The first positioning stopper can be positionally variable in a direction of conveyance of the belt conveyor. This structure of variable positions in the first positioning stopper in the conveyance direction enables the empty bags with different dimensions of length to be supplied.       

     As seen from the above, according to the present invention, in a conveyor magazine, an empty bag is transported with its bottom facing forward, and the orientation of the empty bag being transported is reversed during the transportation (in other words, the bag being conveyed is changed from a bag bottom facing forward transportation to a bag mouth facing forward transportation), and then the empty bag is positioned with respect to (or by) the bag mouth by the second positioning stopper. Accordingly, even the surface of an empty bag becomes wavy, the height of the empty bag can always be kept adequately when the bag is transferred to the gripper of the bag packaging apparatus, and there is no variation from bag to bag regarding the potion at which the gripper grips the bag mouth. This means that empty bags are received assuredly by the gripper, and the height of the bag mouth gripped by the gripper does not vary from bag to bag; and thus, for example, the position or width of the seal part (adhering part) formed at the bag mouth after filling of content is done can be kept constant. 
     When change is made for empty bags supplied to the bag packaging apparatus that have different length dimensions, the location of the conveyor magazine&#39;s first positioning stopper is adjusted (by way of moving it in the direction of conveyance) as necessary in the supply apparatus of the present invention as well; however, in the present invention, positioning for the empty bag that has been fed out of the conveyor magazine is made one more time and this positioning is made with respect to (or by) the bag mouth. Accordingly, the above-described position adjustment for the first positioning stopper does not need to be highly precise, allowing the bag positioning adjustment work to be done easily in a short period of time. The location of the second positioning stopper, which positions the empty bag with respect to (or by) the bag mouth, does not need to be adjusted even when the length of the empty bags is changed. 
     Further, the conveyor magazine of the present invention conveys empty bags with bag bottoms facing forward. Accordingly, it is free of problems of the type (inappropriate fetches and/or inappropriate positioning of empty bags, for instance) that would occur in conveyor magazines in which bags are fed out with the bag mouth facing forward. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side view of the empty bag supply apparatus according to the present invention; 
         FIG. 2  is a top view thereof; 
         FIG. 3  is an enlarged side view primarily showing the left half of  FIG. 1 ; 
         FIG. 4  is an enlarged top view primarily showing the left half of  FIG. 2 ; 
         FIG. 5  is an enlarged side view primarily showing the right half of  FIG. 1 ; and 
         FIG. 6  is an enlarged top view primarily showing the right half of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be described in more detail below with reference to  FIGS. 1 through 6 . 
       FIGS. 1 and 2  show the entirety of the empty bag supply apparatus and show the flow of the steps of the empty bag supply method of the present invention, and  FIGS. 3 through 6  are the partially enlarged views of  FIGS. 1 and 2 . This empty bag supply apparatus can be installed next to, for example, a known intermittently rotating table type bag packaging apparatus (that includes grippers around a table, and only the gripper  1  is shown in the drawings), and it supplies an empty bag  2  to the gripper  1  so that the gripper  1  receives the bag in a substantially vertical attitude with the bag mouth facing upward. The empty bag supply apparatus comprises a conveyor magazine  3 , a first suction device  4 , a first transport device  5 , a second suction device  6 , a suction assistance device  7 , a positioning device  8 , a third suction device  9  and a second transport device  11 . 
     The conveyor magazine  3  itself is of a known technology (see Japanese Utility Model Registration No. 2603966, etc.), and it is equipped with a frame  13  installed on the base  12 , a belt conveyor  14  installed in the center of the frame  13 , guide plates  15  installed on the left and right sides of the belt conveyor  14  on the top surface  13   a  of the frame  13 , and a fast-feed device  16  disposed above the belt conveyor  14 . The conveyor magazine  3  is further equipped with a feed-out device (only the toothed wheels  17  are shown) disposed above the belt conveyor  14  and in the forward position (or on the downstream side in the bag transporting direction, from left to right in  FIG. 1 ) of the fast-feed device  16 , a first positioning stopper  18  which is for positioning an empty bag and installed to project up on the top surface  13   a  of the frame  13 , and a first sensor  19  that detects whether an empty bag on the belt conveyor  14  has come into contact with the first positioning stopper  18 . 
     More specifically, the belt conveyor  14  is comprised of pulleys  21  and  22  rotatably disposed on the frame  13  and four belts  23  provided around the pulleys  21  and  22 . The pulley  21  is linked to a drive source (not shown) and rotated, thus rotatably drive the belts  23 . 
     The fast-feed device  16  is comprised of a drive box  24  installed on the frame  13  and houses inside a drive mechanism that includes a drive source, a rotating pulley  25  connected to the drive mechanism of the drive box  24 , a free arm  26  mounted on the drive box  24  in coaxial with the pulley  25  and able to swing freely, pulleys  27  and  28  mounted on the free arm  26 , and a fast-feed belt  29  wound around the pulleys  25 ,  27  and  28 . A sensor (not shown) that detects the angle of the swing motion of the free arm  26  (which swings up when an empty bag  2  passes under the pulley  27 ) is provided on the fast-feed device  16 , so that the pulley  21  of the belt conveyor  14  rotates continuously (and thus the belt  23  rotates) when the swing angle of the free arm  26  is no more than a predetermined value, and the rotation of the pulley  21  is stopped when the swing angle of the free arm  26  has exceeds the predetermined value. The rotation of the pulley  25  of the fast-feed device  16  is controlled by the detection signal from the first sensor  19 , so that when a bag-not-detected signal is emitted from the first sensor  19  (that means no empty bag in contact with the first positioning stopper  18  detected) for a predetermined length of time, the pulley  25  starts rotating (and thus the fast-feed belt  29  is rotated) and continues the rotation until a bag-detected signal is emitted by the first sensor  19 . The rotation of the fast-feed belt  29  of the fast-feed device  16  is faster than the conveyance speed of the belt conveyor  14 . 
     The toothed wheels  17 , the main part of the feed-out device, are provided so as to be able to move up and down (in the shown embodiment, it swings up and down) and have multiple pliable projections (teeth) around the peripheries (see Japanese Patent Application Laid-Open (Kokai) No. 2003-137219). When bag-not-detected signal from the first sensor  19  has continued a predetermined length of time, the toothed wheels  17  descend and rotate and keep rotating until the first sensor  19  sends out a bag-detected signal (upon an empty bag has come into contact with the first positioning stopper  18 ). The rotation of the outside peripheries of the toothed wheels  17  is faster than the rotation of the belt conveyor  14 . 
     The location of the first positioning stopper  18  is adjustable in the conveyance direction of the belt conveyor  14  (In  FIG. 3 , the first positioning stopper  18  after the location adjustment is done is shown by the dotted line). 
     The group of empty bags  2 A is, as best seen from  FIG. 1 , placed on the belt conveyor  14  of the conveyor magazine  3  so that they are stacked with bag bottoms facing forward and upper bags being shifted forward. The empty bags are conveyed and fed out forward one by one. When an uppermost empty bag  2  of the group of empty bags  2 A comes into contact with fast-feed belt  29 , it is separated from the group of the empty bags  2 A and fast-fed forward, fast-fed forward again by the toothed wheels  17 , and then stopped and positioned when it comes into contact with the first positioning stopper  18 . The part of the empty bag  2  that touches the first positioning stopper  18  at this time is the bag bottom end, and thus the positioning by the first positioning stopper  18  is made with respect to the bag bottom (“bag bottom positioning”). 
     For the first suction device  4  of the shown embodiment of the bag supply apparatus and method of the present invention, only four first suction members  31  thereof are shown (see  FIGS. 1 and 2 ). These first suction members  31  are connected to switching valves and vacuum sources by vacuum piping (not shown), and they can ascend and descend (in the shown embodiment, they ascend and descend by swinging). The first suction members  31  thus suction the upper surface of the empty bag  2  after the bag is brought into contact with and thus positioned by the first positioning stopper  18 , and then the first suction members  31  lift up the empty bag  2  to, as shown in  FIG. 3 , a first transfer position A (the position where the bag is transferred from first suction members  31  to a first transporting member (chucks  35 ) to be described below) shown by the dotted line. When the first sensor  19  sends out the bag-detected signal, the first suction members  31  start vacuum suction, descend simultaneously, suction the spots near the bag bottom on the upper surface of the positioned empty bag  2  and then ascend to lift up mainly at the bottom of the empty bag  2  from the conveyance surface (top surface  13   a ) of the conveyor magazine  3 . When the first suction members  31  ascend, the toothed wheels  17  also ascend simultaneously (see Japanese Patent Application Laid-Open (Kokai) No. 2003-137219). 
     The first transport device  5  of the shown embodiment is provided above the first suction device  4  and is equipped with a drive box  32  which is installed on the base  12  and houses therein an internal drive mechanism. The first transport device  5  further includes a rotary shaft  33  connected to the drive box  32  so as to rotate within a predetermined range, a pair of swing arms  34  affixed to the rotary shaft  33  so as to swing within a predetermined range, a pair of chucks  35  (called a “first transporting member” in the present invention) respectively installed at the tip end of each one of the swing arms  34 , and an air cylinder  36  installed in each swing arm  34  that opens and closes the chuck  35 . 
     As seen from  FIG. 3 , the swing arms  34  swing between the position shown by the solid line and the position shown by the dotted line; and as they swing, the chucks  35  receive the empty bag  2 , which is being suctioned by first suction members  31  and arriving at first transfer position A, from the first suction members  31 , transport it to a higher second transfer position B (the position where the bag is transferred from the first transporting member (chucks  35 ) to second suction members  41  (described below)), and then change the attitude of the bag to substantially vertical with the bag bottom facing upward. The transfer of the empty bag  2  from the first suction members  31  to the chucks  35  is completed after the chucks  35  hold the two side edges of the empty bag  2  near the bag bottom once the bag has arrived at the first transfer position A and the vacuum suction of the first suction members  31  is stopped. 
     The second suction device  6  of the shown embodiment is provided in a forward position (or on the downstream side in the bag transporting direction) of the first transport device  5  and is equipped with a drive box  37  installed on the base  12  and housing therein an internal drive mechanism. The second suction device  6  is, as best seen from  FIG. 6 , further equipped with a rotary shaft  38  connected to the drive box  37  so as to rotate within a predetermined range, a swing arm  39  that is affixed to the rotary shaft  38  and swings within a predetermined range, and two second suction members  41  installed at the tip end of the swing arm  39 . The swing arm  39  swings between the positions shown by the solid and dotted lines in  FIG. 5 ; and as it swings, the second suction members  41  receive the empty bag  2 , which is being held by the chucks  35  in a substantially vertical attitude at the transfer position B, from the chucks  35  and transport it to a lower third transfer position C (where the bag is transferred from the second suction members  41  to the positioning device  8  (described below)). Transfer of the empty bag  2  from the chucks  35  to the second suction members  41  is completed after the second suction members  41  suction the front surface near the bag mouth of the empty bag  2  that has arrived at the second transfer position B, and the air cylinders  36  are activated to open the chucks  35 . 
     The second suction device  6  is for reversing the direction of the empty bag  2  being transported (from a bag bottom facing forward conveyance to a bag mouth facing forward conveyance). Thus, the empty bag  2  suctioned by the second suction members  41  is transported toward the third transfer position C with the bag mouth facing forward. 
     The suction assistance device  7  of the shown embodiment is provided behind the second suction device  6  (or on the upstream side in the bag transferring direction) near the second transfer position B; and it, in addition to the above-described drive box  32  housing therein an internal drive mechanism, is comprised of a rotary shaft  42  connected to the drive box  32  so as to rotate within a predetermined range, a swing arm  43  affixed to the rotary shaft  42  so as to swing within a predetermined range, and a suction assistance plate  44  installed at the tip end of the swing arm  43 . As seen from  FIG. 5 , the swing arm  43  swings between the positions shown by the solid and dotted lines; and as it swings, the suction assistance plate  44  attached to the swing arm  43  is moved back and forth between the retreated position shown by the dotted line and the suction assistance position shown by the solid line. At the retreated position, interference between the suction assistance plate  44  and the empty bag  2  that is being transported to the second transfer position B is prevented. At the suction assistance position, the suction assistance plate  44  opposes the suction surfaces of the second suction members  41 , which suction the front surface of empty bag  2  that is substantially vertical at the second transfer position B, and supports the rear side of the empty bag  2 . The suction assistance plate  44  pushes the empty bag  2  toward the second suction members  41 . 
     Should static electricity or the like causes multiple empty bags to stick together in the conveyor magazine  3  and two or more empty bags  2  be fed out of by the first suction members  31  (“multiple bag transfer”), the two or more empty bags  2  will be transported to the second transfer position B by the chucks  35  and then transferred to the second suction members  41  at the second transfer position B. However, since air will flow in between the two or more empty bags during the transportation by the chucks  35  and separate the bags. Accordingly, when the suction assistance plate  44  withdraws to the retreated position, empty bags other than the empty bag directly suctioned by the second suction members  41  will drop, and the multiple bag transfer is thus resolved. 
     The positioning device  8  (called a “positioning conveyor” in the present invention) of the shown embodiment is provided under the second suction device  6  and is inclined as a whole downward to the front (see  FIGS. 1 and 5 ). The positioning device  8  is comprised of a frame  45  installed on the base  12 , a belt conveyor  46  installed in the center of the frame  45 , and guide plates  47  installed on the left and right sides of the belt conveyor  46  on the top surface  45   a  of the frame  45 . The positioning device  8  is further comprised of toothed wheels  48  disposed above the belt conveyor  46  at the front end of the belt conveyor  46 , a second positioning stopper  49  affixed to the top surface  45   a  of the frame  45  so as to projecting out, a second sensor  51  for detecting whether the empty bag  2  on the belt conveyor  46  has contacted the second positioning stopper  49 , and a pair of lifting members  52  that can project up through the conveyance surface of the belt conveyor  46  from below. 
     The belt conveyor  46  of the positioning device  8  includes pulleys  53  and  54  rotatably disposed on the frame  45  and four belts  55  provided around the pulleys  53  and  54 . The pulley  53  is linked to a drive source (not shown) and rotated, thus rotatably drive the belts  55 . 
     The toothed wheels  48  are the same as the toothed wheel  17  provided for the conveyor magazine  3 . When bag-not-detected signal from the second sensor  51  continues for a predetermined length of time, the toothed wheels  48  are lowered and rotated and continue rotating until the second sensor  51  sends out a bag-detected signal. The rotation of the outside periphery of the toothed wheels  48  is faster than the rotation of the belt conveyor  46 . 
     The lifting members  52  remain below the conveyance surface of the belt conveyor  46  until the second sensor  51  sends out a bag-detected signal, upon which the lifting members  52  are raised above the conveyance surface of the belt conveyor  46 . 
     When the second suction members  41  of the second suction device  6  has transported the empty bag  2  to the lower third transfer position C and vacuum suction of the second suction members  41  is stopped, the empty bag  2  drops onto the belt conveyor  46  of the positioning device  8 . At this point, the transfer of the empty bag  2  from the second suction members  41  to the positioning device  8  is completed. After the empty bag  2  has dropped onto the belt conveyor  46 , the bag is moved forward by its own weight and by the belt conveyor  46 . The empty bag  2  is further moved forward by the toothed wheels  48  and then comes into contact with the second positioning stopper  49  and is thus stopped, so that the empty bag  2  is positioned to lie on the underside on the conveyance surface of the belt conveyor  46 . This positioning of the empty bag in the second suction device  6  is substantially the same as the positioning of the empty bag  2  in the conveyor magazine  3 . However, the difference is that the part of the empty bag  2  that touches the second positioning stopper  49  is the tip end of the bag mouth whereas it is the bag bottom in the conveyor magazine  3 , and the positioning by the second positioning stopper  49  is done with respect to the bag mouth. 
     When the empty bag  2  comes into contact with the second positioning stopper  49  and second sensor  51  emits a bag-detected signal, the lifting members  52  project upwards, raising the bottom end of the underside of the empty bag  2  as shown by the dotted line in  FIG. 5 , which allows a next empty bag to enter the space between the conveyance surface of belt conveyor  46  and the raised empty bag  2 , so that the tip end of the bag mouth of the incoming next empty bag is in contact with the projected lifting members  52  and the next bag is thus stopped. This system increases the processing capacity of the positioning device  8 . 
     The third suction device  9  of the shown embodiment is shown in the drawings by the four third suction members  56  only. The third suction members  56  are connected to switching valves and vacuum sources by vacuum piping (not shown), and they are provided so as to be able to ascend and descend (in the shown embodiment, they ascend and descend by swinging). The third suction members  56  suction the upper surface of the empty bag  2  that is in contact with and positioned by the second positioning stopper  49  and lift the bag to a fourth transfer position D (where the bag is transferred from the third suction members  56  to the second transporting member (chuck  62 ) to be described below) that is shown by the solid line in  FIG. 5 . When the second sensor  51  sends out a bag-detected signal, the third suction members  56  start vacuum suction, descend simultaneously, suction the spots near the bag mouth on the upper surface of the positioned empty bag  2  and then ascend to lift the bag mouth of the empty bag  2  so that the bag mouth side becomes somewhat higher than the bag bottom side. When the third suction members  56  ascend, the toothed wheels  48  also ascend simultaneously (see Japanese Patent Application Laid-Open (Kokai) No. 2003-137219). 
     The second transport device  11  of the shown embodiment is provided above and in a forward position (or on the downstream side in the bag transporting direction) of the third suction device  9 . The second transport device  11  is comprised of a drive box  58  that is installed on the base  57  of a bag packaging apparatus (only the gripper  1  thereof is shown) and houses therein an internal drive mechanism; and the second transport device  11  is further comprised of a rotary shaft  59 , which is connected to the drive box  58  so as to rotate within a predetermined range, and a swing arm  61 , which is affixed to the rotary shaft  59  so as to swing within a predetermined range. In addition, the second transport device  11  is provided with a lever  64  and an air cylinder  65 . The lever  64  is provided at one end thereof with a chuck  62  (called a “second transporting member” in the present invention), and the other end of the lever  64  is linked to the drive box  58  through a link  63 . To the middle portion of the lever  64 , the swing end of the swing arm  61  is rotatably connected. The air cylinder  65  is installed on the lever  64  so that it opens and closes the chuck  62 . This type of second transport device  11  is disclosed in Japanese Patent Application Publication (Kokoku) No. 1995-5125 and thus is a known structure. 
     As the swing arm  61  swings, the lever  64  rotates, as seen from  FIG. 5 , widely between the position shown by the dotted line and the position shown by the solid line; and as the lever rotates, the chuck  62  receives the empty bag  2 , which is suctioned by the third suction members  56  and arriving at the fourth transfer position D, from the third suction members  56 , transports it to a higher fifth transfer position E (where the empty bag  2  is transferred from the second transporting member (chuck  62 ) to the gripper  1  of the bag packaging apparatus), and changes the attitude of the empty bag  2  to substantially vertical with the bag mouth facing upward. The transfer of the empty bag  2  from the third suction members  56  to the chuck  62  is completed after the chuck  62  holds the entire bag mouth of the empty bag  2  which has arrived at the fourth transfer position D and vacuum suction of the third suction members  56  is stopped. 
     The empty bag  2  arriving at the fifth transfer position E is gripped by the gripper  1  at its two edges near the bag mouth and then undergoes various packaging operations in the bag packaging apparatus. 
     In the above-described embodiment, the positioning device  8  is comprised of an inclined belt conveyor  46 . The belt conveyor  46  and the top surface  45   a  of the frame  45  can be, however, horizontal instead of being inclined. A simple inclined chute (positioning chute), instead of the belt conveyor  46 , can also be used as the positioning device. In this case, so as to allow the empty bag  2  to drop down by its own weight, the chute indeed needs to be inclined. 
     In addition, the positioning device  8  is provided with a pair of lifting members  52  that project up through the conveyance surface of the belt conveyor  46  from below. However, a different structure can be employed. For instance, a suctioning member that ascends and descends can be installed above the belt conveyor  46  so as to lift up the bag bottom side of a positioned empty bag  2 , so that the empty bag  2  is suctioned and lifted up by the upper surface.