Patent ID: 8261785

Claim:
A gripper for an automatic bag filling apparatus wherein a plurality of pairs of grippers are provided at equal intervals around a periphery of a transportation member that rotates continuously or intermittently, and said plurality of pairs of grippers respectively grip a gusset bag at two locations on either side edge thereof and are rotated along a predetermined circular path together with said transportation member; each pair of said grippers being comprised of: a pair of left and right gripper arms swingably mounted on said transportation member, chuck holders rotatably mounted respectively on the gripper arms and are moved in parallel when said gripper arms make a swing motion so that a space between the chuck holders is narrowed and widened, inside chuck sections and outside chuck sections provided in the tip end portions of the chuck holders so to face each other, an inside chuck open/close mechanism and an outside chuck open/close mechanism provided in each one of the chuck holders and respectively open and close said inside and outside chuck sections, and an inside/outside chuck positioning mechanism provided in each one of the chuck holders and moves the inside chuck section and outside chuck section inwardly and outwardly between a close position and a separate position; and wherein said inside chuck section comprises an inside fixed chuck element, having a gripping surface facing inward, and an inside movable chuck element, so that said inside fixed and movable chuck elements grip one of the two locations on the side edge of the gusset bag in between, and said outside chuck section comprises an outside fixed chuck element, having a gripping surface facing outward, and an outside movable chuck element, so that said outside fixed and movable chuck elements grip another one of the two locations on the side edge of the gusset bag in between; and wherein said inside chuck open/close mechanism is comprised of: a first tubular member slidably provided within each of said chuck holders, and a first air cylinder installed within a tube body of said first tubular member; and said inside movable chuck element which is affixed to a tip end of said first tubular member is opened and closed with respect to said inside fixed chuck element by advance and retreat motions of a piston rod of said first air cylinder; and said outside chuck open/close mechanism is comprised of: a second tubular member slidably provided within said each of said chuck holders, and a second air cylinder installed within a tube body of said second tubular member, and said outside movable chuck element which is affixed to a tip end of said second tubular member is opened and closed with respect to said outside fixed chuck element by advance and retreat motions of a piston rod of said second air cylinder.