Apparatus for heat-sealing thermoplastic sheeting

Apparatus for heat sealing thermoplastic sheeting comprising a frame, a clamping jaw having a clamping surface, means mounting said clamping jaw on said frame, a heating jaw having heating means, means mounting said heating jaw on said frame for movement between a disposition spaced-apart from said clamping jaw and a disposition adjacent said clamping jaw for gripping and heat sealing thermoplastic sheeting between said clamping surface and said heating means, means for latching said heating jaw to be substantially fixed in its said adjacent disposition, said clamping jaw mounting means including means for biasing said clamping jaw at plural spaced locations thereon for translatory movement toward said heating jaw in its said adjacent disposition automatically to orient and to engage said clamping surface in substantially continuous and uniform surface contact with said heating means for uniformly applying said heating means to thermoplastic sheeting gripped between said jaws, said biasing means including a plurality of linear actuators mounted on said frame, each said linear actuator comprising a piston and cylinder assembly having a reciprocable piston adapted to be operated by pressurized fluid, said clamping jaw being mounted at its said spaced locations respectfully on said reciprocable pistons of said linear actuators, said biasing means including a source of pressurized fluid, conduit means for supplying said pressurized fluid to said piston and cylinder assemblies, and means in said conduit means for regulating said pressurized fluid at a predetermined uniform pressure value.

Apparatus for heat sealing thermoplastic sheeting comprising a frame, a clamping jaw having a clamping surface, means mounting said clamping jaw on said frame, a heating jaw having heating means, means mounting said heating jaw on said frame for movement between a disposition spaced-apart from said clamping jaw and a disposition adjacent said clamping jaw for gripping and heat sealing thermoplastic sheeting between said clamping surface and said heating means, means for engaging said heating jaw at spaced locations thereon in its adjacent disposition and moving said heating jaw toward said clamping jaw for translatory movement automatically to orient and to engage said heating means in substantially continuous and uniform surface contact with said clamping surface for uniformly applying said heating means to thermoplastic sheeting gripped between said jaws, said heating jaw being resiliently deformable by manipulation at said spaced locations and said engaging and moving means being adapted for deforming said heating jaw to such extent necessary to obtain substantially continuous and uniform surface contact between said heating means and said clamping surface, said engaging and moving means including a plurality of linear actuators, each said linear actuator comprising a piston and cylinder assembly having a reciprocable piston adapted to be operated by pressurized fluid, said linear actuators being mounted on said frame for latching engagement of their said reciprocable pistons with said heating jaw in its said adjacent disposition respectively at its said spaced locations for moving said heating jaw toward said clamping jaw, said engaging and moving means including a source of pressurized fluid, conduit means for supplying

• said pressurized fluid to said piston and cylinder assemblies, and means in said conduit means for regulating said pressurized fluid at a predetermined uniform pressure value.

An L-sealing apparatus for heat sealing folded thermoplastic film along an L-shaped seal line comprising a frame having a sealing table surface, a clamping jaw having an L-shaped sealing bed surface, means mounting said clamping jaw on said frame with said sealing bed surface generally adjacent said sealing table surface, a heating jaw having L-shaped heating means thereon, means pivotably mounting said heating jaw on said frame for pivotal movement between a disposition spaced-apart from said clamping jaw for permitting placement of thermoplastic film to be heat sealed on said table surface and said sealing bed surface and a disposition adjacent said clamping jaw with said heating means in facing relation with said sealing bed surface for gripping and heat sealing thermoplastic film therebetween, and means for latching said heating jaw to be substantially fixed in its said adjacent disposition, said clamping jaw mounting means including means for biasing said clamping jaw at the locations of each of the ends and the corner of said L-shaped sealing bed surface for translatory movement toward said heating jaw in its adjacent disposition automatically to orient and to engage said sealing bed surface in parallelism and substantially continuous and uniform surface contact with said heating means along substantially their entire L-shaped extent for uniformly applying said heating means to thermoplastic film gripped between said jaws, said biasing means including a plurality of linear actuators mounted on said frame and arranged to exert generally the same biasing force on said clamping jaw at each said end and corner location for exerting uniform sealing pressure against said heating jaw, each said linear actuator comprising a piston and cylinder assembly having a reciprocable piston adapted to be operated by pressurized fluid, said clamping jaw being mounted at its said end and corner locations respectively on said reciprocable pistons of said linear actuators, said biasing means including a source of pressurized fluid, conduit means for supplying said pressurized fluid to said piston and cylinder assemblies, and means in said conduit means for regulating said pressurized fluid at a predetermined uniform pressure value.