Patent GB-1429364-A (GB)
Title: Strip adhesive application machine
IPC: B31B19/00
Filed: 1973-07-30
Abstract: 1429364 Machines for applying adhesive strips; plastics bags MINNESOTA MINING & MFG CO 30 July 1973 36269/73 Headings B8F and B8K A machine for cutting pressure-sensitive adhesive strip 16 on a carrier web 18 to form a predetermined length of strip and transferring said length from the web on to a polyethylene packaging envelope 14 to form reclosable sealing tab 12 comprises a first support 28, and second support 30 mounted on rods 32 for reciprocal movement to and from the first support, a pressure foot 26 mounted on the second support for pressing the cut-adhesive strips on to the envelope when the second support is moved towards the first support, upstream and downstream drive rollers 74 and 80 for incrementally advancing the web by said predetermined length, a knife 82 mounted on the second support and co-operable with the foot to cut the adhesive strip into said predetermined lengths whilst on the web without severing the web, and a holding plate 40 movably mounted on the second support by means of slots 48, studs 50 and springs 52 for resiliently engaging and pressing the envelope against the first support prior to engagement thereof by the foot and for maintaining said engagement until the foot and second support have moved at least partly back away from the first support, thereby facilitating separation of the cut-length of adhesive from the carrier web. The knife is biased by a spring 94 to bear against the adhesive strip and thus sever the same without cutting through the carrier web. A conveyer 22 feeds the envelope into a position above the first support, and a pneumatic cylinder 96 is actuated to extend a cam ram 98, which pivots the knife away from the anvil surface 90 of the pressure foot. A pneumatic cylinder 108 is then actuated to advance a rack 110 to effect, through a one-way clutch and chain drive 106, rotation of the drive rollers 74 and 80 thereby advancing the cut length of adhesive strip on the carrier web into the base of the pressure foot. The blade is then allowed to move back into engagement with advanced adhesive strip and web by retraction of the ram cam 98, the blade being biased by spring pressure with sufficient force to drift through the adhesive strip. The holding plate and pressure foot are then sequentially pressed against the envelope on actuation of a pneumatic cylinder 36, which moves the second support bodily towards the first support. On initial retraction of the second support, and hence the pressure foot, the holding plate maintains pressure on the envelope to facilitate separation of the cut-adhesive strip, which has been pressed on to the envelope, from the carrier web. Air jets are directed from opposed slots 58 in the holding plate to aid web/strip separation. The drive roller 80 is larger than the drive roller 74 so that it travels at higher peripheral speed, the consequential slippage between the web and roller 80 tensioning the web about the pressure foot. A spring-biased roller 76 engages between the drive roller nip to ensure web drive. The actuation of the pneumatic cylinders effecting operation of the knife, drive rollers, second support, and air jets is controlled by valves 136, 138, 144, and 55, Fig. 8 (not shown), actuated by cams 134, 140, 142, and 146 on a common shaft 132, which is coupled to the envelopeconveyer drive.