Bag opening apparatus and bag opening method

Abstract

A bag opening apparatus and a bag opening method capable of efficiently opening a bag body in a short period of time are provided. A bag opening apparatus includes a gap formation unit which bends at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap. When a first press drive member presses a first holding unit against the front wall portion, a contact part of the first holding unit is swung against urging force of an urging part of the first holding unit to bend the front wall portion.

1 . A bag opening apparatus comprising a gap formation unit which bends at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein:
 the gap formation unit includes a first holding unit and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion,   the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and   when the first press drive member presses the first holding unit against the front wall portion, the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion so as to bend the front wall portion.   
     
     
         2 . The bag opening apparatus as defined in  claim 1 , wherein:
 the gap formation unit further includes a second holding unit,   the first press drive member moves not only the first holding unit but also the second holding unit between the position where the first holding unit and the second holding unit are separated from the front wall portion and the position where the first holding unit and the second holding unit are pressed against the front wall portion, and   when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the first holding unit is swung so as to approach the second holding unit while the contact part of the first holding unit is in contact with the front wall portion.   
     
     
         3 . The bag opening apparatus as defined in  claim 2 , wherein:
 the second holding unit includes a contact part, a support part which swingably supports this contact part, and an urging part which urges this contact part via the support part, and   when the first press drive member presses the first holding unit and the second holding unit against the front wall portion, the contact part of the second holding unit Is swung against urging force of the urging part of the second holding unit so as to approach the contact part of the first holding unit while the contact part of the second holding unit is in contact with the front wall portion.   
     
     
         4 . The bag opening apparatus as defined in  claim 1 , further comprising an air blowing unit which ejects air toward the gap. 
     
     
         5 . The bag opening apparatus as defined in  claim 2 , further comprising an air blowing unit which ejects air toward the gap. 
     
     
         6 . The bag opening apparatus as defined in  claim 3 , further comprising an air blowing unit which ejects air toward the gap. 
     
     
         7 . The bag opening apparatus as defined in  claim 3 , wherein:
 the gap formation unit further includes: a third holding unit and a fourth holding unit; and a second press drive member which moves the third holding unit and the fourth holding unit between a position where the third holding unit and the fourth holding unit are separated from the back wall portion and a position where the third holding unit and the fourth holding unit are pressed against the back wall portion, and   in a state where the contact part of the first holding unit and a contact part of the third holding unit are opposed to each other via the front and back wall portions and the contact part of the second holding unit and a contact part of the fourth holding unit are opposed to each other via the front and back wall portions, the first press drive member presses the first holding unit and the second holding unit against the front wall portion, and the second press drive member presses the third holding unit and the fourth holding unit against the back wall portion.   
     
     
         8 . The bag opening apparatus as defined in  claim 1 , wherein:
 the gap formation unit further includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and   the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.   
     
     
         9 . The bag opening apparatus as defined in  claim 2 , wherein:
 the gap formation unit further Includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and   the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.   
     
     
         10 . The bag opening apparatus as defined in  claim 3 , wherein:
 the gap formation unit further includes a receiving part which are disposed on a side of the back wall portion and has a receiving surface facing the back wall portion, and   the first press drive member presses the first holding unit against the front wall portion in a state where the front wall portion and the back wall portion are sandwiched by the first holding unit and the receiving surface.   
     
     
         11 . The bag opening apparatus as defined in  claim 8 , wherein the receiving part includes a first elastic member forming the receiving surface. 
     
     
         12 . The bag opening apparatus as defined in  claim 9 , wherein the receiving part includes a first elastic member forming the receiving surface. 
     
     
         13 . The bag opening apparatus as defined in  claim 10 , wherein the receiving part includes a first elastic member forming the receiving surface. 
     
     
         14 . The bag opening apparatus as defined in  claim 1 , wherein:
 the first holding unit includes:   a first link which is attached to the first press drive member and swingably supports one side of the support part of the first holding unit, and   a second link which is attached to the first press drive member so as to be capable of moving back and forth and swingably supports another side of the support part of the first holding unit, and   when the first press drive member presses the first holding unit against the front wall potion, the urging part of the first holding unit urges the contact part of the first holding unit, via the second link and the support part of the first holding unit, in a direction including a component of a direction opposing a direction in which the contact part of the first holding unit is swung.   
     
     
         15 . The bag opening apparatus as defined in  claim 1 , wherein the contact part includes a second elastic member. 
     
     
         16 . The bag opening apparatus as defined in  claim 1 , further comprising a pair of grippers which holds both side portions of the bag body,
 wherein before or while the first press drive member presses the first holding unit against the front wall portion to cause the contact part of the first holding unit to swing, at least one of the grippers is moved in such a manner that a distance between the grippers is reduced.   
     
     
         17 . A bag opening method causing a bag opening apparatus to bend at least a front wall portion, of the front wall portion and a back wall portion that constitute a mouth portion of a bag body, so as to form a gap between the front wall portion and the back wall portion, wherein:
 the bag opening apparatus includes a gap formation unit having: a first holding unit; and a first press drive member which moves the first holding unit between a position where the first holding unit is separated from the front wall portion and a position where the first holding unit is pressed against the front wall portion,   the first holding unit includes a contact part, a support part which swingably supports the contact part, and an urging part which urges the contact part via the support part, and   the bag opening method includes a step of bending the front wall portion by causing the first press drive member to press the first holding unit against the front wall portion in such a manner that the contact part is swung against urging force of the urging part while the contact part is in contact with the front wall portion.