Packaging machine with continuous motion top sealer

Mechanism for sealing the tops of upright pouches adapted to be advanced continuously at a predetermined speed and in spaced relationship around an arcuate path, said mechanism comprising a turret supported to rotate about an upright axis which coincides with the center of said path, a plurality of sealing heads carried by said turret in overlying relation with said path and spaced angularly from one another in accordance with the spacing of said pouches, means for continuously rotating said turret about said axis at a speed and in a direction to cause said sealing heads to match the speed and direction of said pouches as the latter are advanced along said path, each of said sealing heads comprising a pair of opposing heated sealing bars mounted on said turret to move downwardly and upwardly in unison between a raised position in which the bars are spaced upwardly from the underlying pouch to a lowered position in which the bars straddle the top of such pouch, one of said bars being mounted relative to the other bar to move toward and away from said other bar between open and closed positions, a reversible actuator connected to each sealing head, said actuator being operable when actuated in one direction to first move said sealing bars downwardly in unison from said raised position to said lowered position and thereafter to move one sealing bar toward said other sealing bar from said open position to said closed position, said actuator being operable when actuated in the reverse direction to first move said one sealing bar away from said other sealing bar to said open position and thereafter to move said sealing bars upwardly in unison to said raised position.

Mechanism for sealing the tops of upright pouches adapted to be advanced continuously at a predetermined speed and in spaced relationship around an arcuate path, said mechanism comprising a turret supported to rotate about an upright axis which coincides with the center of said path, a plurality of sealing heads carried by said turret in overlying relation with said path and spaced angularly from one another in accordance with the spacing of said pouches, means for continuously rotating said turret about said axis at a speed and in a direction to cause said sealing heads to match the speed and direction of said pouches as the latter are advanced along said path, each of said sealing heads comprising a pair of opposing heated sealing bars mounted on said turret to swing downwardly and upwardly in unison about a first predetermined axis between a raised position in which the bars are spaced upwardly from the underlying pouch to a lowered position in which the bars straddle the top of such pouch, one of said bars being mounted relative to the other bar to swing toward and away from said other bar between open and closed positions about a second predetermined axis paralleling said first axis, a stationary cam track extending around at least part of said turret, a reversible actuator connected to each of said sealing heads and having an element which engages and moves along said cam track, said cam track being operable to shift said actuator first in one direction and subsequently in the opposite direction as said actuator moves along said cam track, said actuator including means for causing said bars to swing downwardly in unison to their lowered position when said actuator is first shifted in said one direction and for thereafter causing said one sealing bar to swing to its closed position when said actuator is subsequently shifted in said one direction, means for positively holding said one sealing bar in its closed position independently of said cam track for a period of time after said one sealing bar has been shifted to its closed position, and said actuator further including means for causing said one sealing bar to swing to its open position when said actuator is first shifted in said opposite direction and for thereafter causing said sealing bars to swing upwardly in unison to their raised position when said actuator is subsequently shifted in said opposite direction.