A method for continuously forming bags comprising continuous steps of heat-sealing a continuous tubular plastic film, such as a continuously formed inflation tube or the like, widthwise at given positions thereof while the tubular film is being conveyed, cutting sequentially the tubular film along the heat-seals into bag-shaped containers, and conveying the tubular film over a set distance to a following step while the heat-seals of the heat-sealed tubular film being press-held and cooled. Also the present invention relates to an apparatus for continuously forming bags for heat-sealing a continuous tubular plastic film, such as a continuously formed inflation tube or the like, widthwise at given positions thereof while the tubular film is being conveyed, and then cutting the tubular film along the heat-seals into bag-shaped containers. The apparatus comprises heat-sealing device for sealing the tubular film including a pair of heat-sealing members which are disposed on one side of a track of conveyance of the tubular film, opposing each other so as to hold the tubular film therebetween, and are movable to and from each other, driving device for driving the heat-sealing device to and from each other, cooling device for cooling the tubular film including a pair of cooling sandwiching members which are supported on a movable member disposed movably in directions of width of the tubular film and conveyance thereof, and intrude inbetween the heat-sealing members to sandwich the heat-seals of the tubular film, and driving device for driving the cooling sandwiching members to and from each other, whereby the tubular film is conveyed by a movement of the movable member to a next step with the those parts of the tubular film at the heat seals held between the cooling sandwiching members.

A cross sealer for a plastic bag making machine includes a frame with an upper moveable seal bar unit and an opposed lower stationary seal bar unit. The movable unit is a lightweight construction seal beam. A rotating shaft spans the cross sealer and is connected by a plurality of eccentric linkages to the seal beam. The linkages moves a seal bar into sealing engagement across the width of the web to the seal bar unit constructed with a support beam and a seal bar connected to the beam. The seal bar unit is mounted as a substantially stationary unit during sealing and is supported by a plurality of air cylinder units for positioning from standby to an operating position. Each air cylinder unit includes an adjustable stop unit secured to the back of the cylinder unit and connected to the cylinder piston for adjusting the movement of the piston and thereby the operative sealing position of the stationary seal bar unit. Some air cylinder units are connected to the seal bar unit for positively moving the same and others additionally includes pad abutting the seal bar units for supporting the same between the two positions.

A low thermal inertia die (10) must be heated to a specific set temperature to cut/seal plastics material. As heat energy is dissipated during cutting/sealing it is replaced by an equivalent amount of thermal energy from an electrical heating element (26) embedded in the die, adjacent the profiled working face (22) which in use contacts plastics material. The element (26) is covered in electrically non-conductive tape (28) and encased in flattened steel tube (30). A thermocouple (32) is also embedded in the die (10), with its tip (34) located to sense the temperature of a central region of the working face (22). The electrical current supplied to the electrical resistance heating element (26) is controlled in dependence upon the temperature sensed.

The present invention relates to a sealing apparatus for sealing foil material, the apparatus comprising a foil conveying means and a sealing means including a sealing head which has at least one sealing position for performing the foil sealing operation, an intermediate position in which the sealing head has a predetermined distance from the sealing position, and an inoperative position in which the sealing head has a second predetermined distance from the sealing position that is greater than the first distance. Furthermore, the invention relates to a corresponding sealing method which can be carried out with the sealing apparatus, wherein the sealing head is removed from the foil material to a first distance during the further transporation of the foil material and is removed from the foil material to a second greater distance when the foil sealing operation is interrupted.

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.