Carton sealing method and apparatus

Claim 1

Apparatus for forming a seal between layers of a carton of thermoplastic coated paperboard material and the like wherein the thermoplastic material of the layers in the area to be sealed serves as the sealant and is activated by frictional heat from a vibration welding horn and then allowed to cool and set under pressure to form a seal between the layers, said apparatus comprising: means defining a sealant activating station at one location; means defining a clamping and sealing station at another location; back-up means extending between said stations, said back-up means having a work surface for engaging one outer surface of the layers in the area to be sealed; a holding member extending between said stations, said holding member overlying said back-up means for engaging said opposite outer surface of the layers to hold the layers together in cooperation with the back-up means when a carton is located at either of said stations or between said stations; a horn located at said acitvating station that vibrates at a predetermined frequency when energized; said horn having a work surface for engaging the opposite outer surface of the layers in the area to be sealed and that opposes the work surface on the back-up means at the activating station; said horn being movable with respect to said back-up means between a retracted inactive position and an extended active position in which the opposed work surfaces of the horn and back-up means engage the layers to be sealed in a clamping relationship such that vibration of said horn generates frictional heat to activate the thermoplastic material of said layers; a pressure pad located at said clamping and sealing station; said pressure pad having a work surface for engaging said opposite outer surface of the layers and that opposes the work surface of the backup means at the clamping and sealing station; said pressure pad being movable with respect to said back-up means between a retracted inactive position and an extended active position in which the opposed work surfaces of the pressure pad and back-up means engage the layers to be sealed in a clamping relationship; said horn being operable to move from the retracted inactive position when a carton is placed into the activating station and return to the retracted inactive position after remaining in the active position with the horn energized a predetermined period of time sufficient to activate the thermoplastic material; carton carrying means operable to carry a carton with activated thermoplastic from the activating station upon retraction of the horn to the clamping and sealing station prior to cooling and setting of the activated thermoplastic; said pressure pad being operable to move from the retracted inactive position to the extended active position when a carton with activated thermoplastic moves into the clamping and sealing station to clamp the layers with activated thermoplastic together and return to the retracted inactive position after remaining in the active position a predetermined period of time sufficient to permit the activated thermoplastic to cool and set.

Claim 37

A method of forming seals between the layers of the end closures of thermoplastic coated paperboard cartons by vibration welding comprising the steps of: moving each carton into a position in which its end closure is disposed between the spaced apart work surfaces of a vibrating horn and back-up member; pretriggering the horn to energize it and cause it to vibrate at a predetermined frequency; moving the work surfaces of the back-up member and energized horn into opposed, clamping relationship with the layers of the end closure at a clamping pressure within predetermined limits over the entire area of the layers between the work surfaces; holding the energized horn in said clamping relationship for a predetermined period of time to activate the thermoplastic coating to flow; de-energizing the horn while still in the clamping position and holding the de-energized horn in said clamping position for a predetermined period of time to permit the activated thermoplastic to partially set; separating the work surfaces of the de-energized horn and back-up member; moving the carton with the partially activated thermoplastic to a cooling and clamping station with the end closure disposed between the spaced apart work surfaces of a pressure pad and back-up member; moving the work surfaces of the pressure pad and back-up member into opposed, clamping relationship with the layers of the end closure at a predetermined clamping pressure; holding the pressure pad in said clamping relationship for a predetermined period of time to permit the thermoplastic to complete this set; and then separating the work surfaces of the pressure pad and back-up member to permit the carton end closure to be moved from the clamping and sealing station.

Claim 38

A method of forming seals between the layers of the end closures of thermoplastic coated paperboard cartons by vibration welding comprising the steps of: moving each carton into a position in which its end closure is disposed between the spaced apart work surfaces of a vibrating horn and back-up member; pretriggering the horn to energize it and cause it to vibrate at a predetermined frequency; moving the work surfaces of the back-up member and energized horn into opposed, clamping relationship with the layers of the end closure at a clamping pressure within predetermined limits over the entire area of the layers between the work surfaces; holding the energized horn in said clamping relationship for a predetermined period of time to activate the thermoplastic coating to flow; de-energizing the horn while still in the clamping position and holding the de-energized horn in said clamping position for a predetermined period of time to permit the activated thermoplastic to partially set; separating the work surfaces of the de-energized horn and back-up member; moving the carton with the partially activated thermoplastic to a cooling and clamping station with the end closure disposed between the spaced apart work surfaces of a pressure pad and back-up member; moving the work surfaces of the pressure pad and back-up member into opposed, clamping relationship with the layers of the end closure at a predetermined clamping pressure; holding the pressure pad in said clamping relationship for a predetermined period of time to permit the thermoplastic to complete this set; and then separating the work surfaces of the pressure pad and back-up member to permit the carton end closure to be moved from the clamping and sealing station.

Claim 39

A method of closing the end closure of a thermoplastic coated paperboard carton and sealing the layers of the end closure by vibration welding comprising the steps of: moving the carton with the open end closure between a pair of closing members having spaced apart edges to define a closing slot with the edges of the closing members converging from a wide end to a narrow end to close the layers of the end closure together; moving the closed end closure between a holding member and a working surface of a back-up member with an activating station and clamping and sealing station defined at spaced locations along the holding member and back-up member; pretriggering a vibrating welding horn at the activating station to cause it to vibrate at a predetermined frequency; moving the work surface of the vibrating horn into clamping relationship with the layers of the end closure and holding the vibrating horn in said clamping relationship for a predetermined period of time to activate the thermoplastic coating of the paperboard layers to flow; de-energizing the horn while still in the clamping position and holding the de-energized horn in said clamping position for a predetermined period of time to permit the activated thermoplastic to partially set; separating the work surface of the horn to permit the carton end closure to be advanced from the activating station to the clamping and sealing station while the layers are still held closed together between the holding member and work surface of the back-up member; moving the work surface of a pressure pad into clamping relationship with the end closure for a predetermined period of time to permit the thermoplastic material to completely set, and then separating the pressure pad work surface from the end closure to permit the carton end closure to be moved from the clamping and sealing station.

Claim 40

A method of closing the end closure of a thermoplastic coated paperboard carton and sealing the layers of the end closure by vibration welding comprising the steps of: moving the carton with the open end closure between a pair of closing members having spaced apart edges to define a closing slot with the edges of the closing members converging from a wide end to a narrow end to close the layers of the end closure together; moving the closed end closure between a holding member and a working surface of a back-up member with an activating station and clamping and sealing station defined at spaced locations along the holding member and back-up member; pretriggering a vibrating welding horn at the activating station to cause it to vibrate at a predetermined frequency; moving the work surface of the vibrating horn into clamping relationship with the layers of the end closure and holding the vibrating horn in said clamping relationship for a predetermined period of time to activate the thermoplastic coating of the paperboard layers to flow; de-energizing the horn while still in the clamping position and holding the de-energized horn in said clamping position for a predetermined period of time to permit the activated thermoplastic to partially set; separating the work surface of the horn to permit the carton end closure to be advanced from the activating station to the clamping and sealing station while the layers are still held closed together between the holding member and work surface of the back-up member; moving the work surface of a pressure pad into clamping relationship with the end closure for a predetermined period of time to permit the thermoplastic material to completely set, and then separating the pressure pad work surface from the end closure to permit the carton end closure to be moved from the clamping and sealing station.