Plastic bag opening apparatus

Abstract

A plastic bag opening apparatus is provided by which plastic bags stacked with pins being inserted into pin holes are smoothly opened and delivered one by one from the uppermost one of the plastic bags. The apparatus comprises a center holding member ( 13 ) pressing elongations ( 2 ) of bags ( 1 ) between two pin holes ( 3 ) and side holding members ( 14 ) pressing the elongations ( 2 ) on both outer sides of the pin holes ( 3 ). Pressing of the elongations ( 2 ) by the holding members ( 13 ), ( 14 ) is released by rotation of a rotating member ( 17 ), ( 37 ) around a rotating shaft ( 18 ), ( 38 ). When the elongations ( 2 ) are to be pressed, the rotating member ( 17 ), ( 37 ) is vertically positioned so that a pushing-up force acting on the elongations ( 2 ) is received by the rotating member ( 17 ), ( 37 ) in a dead point state in the vertical direction. A control device controls such that when the bag 1 is to be opened by being blown with air, the pressing by the side holding members ( 14 ) is released and when the bag 1 so opened is to be discharged, the side holding members ( 14 ) press the remainder of the stacked plastic bags 1 and the pressing by the center holding member ( 13 ) is released.

1 . A plastic bag opening apparatus constructed to open plastic bags, where each of said plastic bags has one edge of its opening portion elongated to form an elongation, said elongation is provided with two pin holes and said plastic bags are held together in a stack with pins, having their upper ends free, being inserted into said pin holes and opened one by one from the uppermost one of said plastic bags in the stack by being blown with air obliquely from above, wherein said plastic bag opening apparatus comprises a center holding member to press said elongations between said two pin holes, side holding members to press said elongations on both outer sides of said pin holes and a control device to control movements of said center holding member and side holding members such that when said plastic bags are to be opened by the air blowing, the pressing by said side holding members is released and when said plastic bags so opened are to be discharged, said side holding members press the remainder of said plastic bags in the stack and the pressing by said center holding member is released and each of said center holding member and side holding members is constructed such that the pressing of said elongations and release thereof are carried out by rotation of a rotating lever around a rotating shaft and when said elongations are to be pressed, said rotating lever is vertically positioned so that a pushing-up force acting on said elongations is received by said rotating lever in a dead point state in the vertical direction.  
   
   
       2 . A plastic bag opening apparatus as claimed in  claim 1 , wherein said rotating shaft to rotate said rotating lever for moving said center holding member and side holding member is constructed to be rotated by elongation and contraction of an air cylinder.  
   
   
       3 . A plastic bag opening apparatus as claimed in  claim 2 , wherein the pressing by said center holding member and side holding member and release thereof are carried out by a construction such that said rotating lever has its one end fitted with an engaging roller and a member having a slot with which said engaging roller engages is moved by rotation of said rotating lever around said rotating shaft.