Abstract: The sealing of plastic bags filled with a particular product, for example bread, is commonly achieved by folding a length of adhesive tape (1) around the gathered neck (10) of the bag. The adhesive tape (1) is folded such that the ends of the tape stick to each other to form a closed loop. A bag tying machine for sealing bags in this way includes a roll of adhesive tape (1) having spaced portions (3) which are non-adhesive, wherein the tape is wholly coated with adhesive and the non-adhesive portions are portions which have been treated to neutralise the adhesive; a detector (14) for detecting the boundary between the adhesive and non-adhesive portions of the adhesive tape (1); and, cutting means (13) for cutting the adhesive tape (1) into individual ties wherein the cutting means (13) cut the tape (1) at positions according to boundary position data received from the detector (14).

Abstract: Bag tying machine with a pair of pivoted arms (1,2), a pair of leaf springs (3) between the two arms (1,2) to form a first abutment, and a second abutment (5), preferably formed from a pair of rollers. In use, the open neck of a bag is passed between the arms (1,2) and is gathered together by the leaf springs (3). The gathered together neck of the bag is pushed onto an adhesive tape which is wrapped around the neck of the bag as this passes through the second abutment. The downstream ends of the arms (1,2) are urged together by pneumatic cylinders (6). These are advantageously controlled by a variable pressure controller (9).