Sealer apparatus for forming a cross seal in plastic film processing and particularly for bag making machines

Abstract

A cross sealer for a bag making machine includes a frame with an upper seal bar unit and a lower seal bar unit in aligned opposed relation. One is movable seal bar unit which includes a rigid support beam of a lightweight construction and a light weight seal bar connected to the beam by a plurality of adjustable stud units for adjusting the position of the seal bar. A rotating shaft spans the cross sealer and is connected by a plurality of eccentric linkages to the beam between side plates of the frame. The linkages support the beam and seal bar and transfers the sealing force onto the beam and bar for moving the bar into sealing engagement across the width of the web. The opposed seal bar unit is similarly constructed with a beam and a seal bar with the units interconnected by adjustable stud connectors. The second seal bar unit is mounted as a substantially stationary unit and includes a plurality of substantially fixed connectors supporting of the fixed beam along a plurality of locations to form a relatively rigid beam support. Alternate fixed beam supports include air cylinders to provide a cushion support for the seal unit. The connecting studs in the opposed seal units are offset to allow the respective beams to deflect and conform more fully to each other and to form an effective smooth and constant seal across the web. The eccentric shaft is shown driven by a servo motor and alternatively by a fluid cylinder and linkage drive unit. The drive system includes a controlled drive and linkage to provide for various seal dwell periods and configurations.