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A method and apparatus for sealing a flat lid with a lower layer of heat bondable material onto the upper, generally flat surface of a flange extending around the periphery of an access opening in a container of the type used to store a substance susceptible to deterioration when exposed to atmosphe

A method and apparatus for sealing a flat lid with a lower layer of heat bondable material onto the upper, generally flat surface of a flange extending around the periphery of an access opening in a container of the type used to store a substance susceptible to deterioration when exposed to atmosphere for a prolonged time such as prepared foods, which method and apparatus moves a separate and distinct heating unit with a downwardly facing heating ring in a preselected path, preferably circular in shape, between first and second positions, includes a generally fixed high frequency power supply for energizing said heating ring, connects this fixed high frequency power supply to the individual heating rings of the moving heating unit only when the unit is moving between the first and second positions, and energizes the power supply only while the heating unit is moving between the first and second positions. The ring is forced against the lid as the power supply is energized and is released from the ring from the lid after the power supply has been de-energized and before the moving heating unit reaches the second position. Preferably the ring is an inductor and the plurality of heating units are carried by a turret to define individual heating stations on the turret which stations rotate to selectively energize the individual heating units by the single fixed high frequency power supply whereby single power supply energizes a plurality of separate heating stations.

대표청구항 ▼

In a device for sealing a flat lid with a lower layer of heat bondable material onto the upper, generally flat surface of a generally flat flange extending around the periphery of an access opening in a container for hermetically storing a substance susceptible to deterioration when exposed to atmos

In a device for sealing a flat lid with a lower layer of heat bondable material onto the upper, generally flat surface of a generally flat flange extending around the periphery of an access opening in a container for hermetically storing a substance susceptible to deterioration when exposed to atmosphere for a prolonged time, said device comprising: a turret having a given number of circumferentially spaced stations; means for rotating said turret about a veertical axis whereby said stations move along a generally circular path; means for loading a container filled with said substance onto a station of said turret at a first position on said path; means for locating a lid over said container at a second position on said path; and, means for heating said heat bondable material while said lid is forced against said flange at a third position on said path whereby said lid is sealed onto said flange of said container wherein said heating means including a heating unit at each of said stations and each including a downwardly facing heating ring adapted to force said lid against said flange and electrical means for causing said ring to heat said lid in a pattern defined by said ring and extending around said flange periphery whereby said heat bondable material is heated to a lid sealing temperature along said pattern at said third position of said path; said electrical means comprising an high frequency power supply fixedly mounted with respect to said rotable turret, a switch plate having a given number of circumferentially spaced contacts rotatable with said switch plate as it is rotated in unison with said turret about said axis, bus means on said turret for fixedly connecting each ring of each of said heating units at a given station to a selected contact of said switch plate and brush means connected to said high frequency power supply and including brush contacts riding on said switch plate, said given number of contacts on said switch plate being spaced to correspond with said given number of stations whereby each of said heating units is energized by said power supply for an heating cycle while said energized heating unit is in a preselected arc of said third position of said path.