Method and apparatus for heat-sealing container

Abstract

A heat welding member 23 of a seal head 21 formed in the shape of a flange portion 11 a of a container 10 is heated by high frequency induction heating and a cap 12 is welded by pressing the heated seal head 21. By using the seal head 21 comprising the heat welding member 23 having a shape necessary for sealing the cap 12, influences by temperature drop and inflation of gas in a head space can be prevented and sealing at a high speed and in a stable manner can be achieved.

1 . A method for heat-sealing a container by sealing the container by heat welding a cap on a flange portion provided in an opening portion of the container comprising a step of high frequency induction heating a seal head formed in the shape of the flange portion of the container and pressing the cap with the heated seal head to weld the cap to the container. 
     
     
         2 . A method for heat-sealing a container as defined in  claim 1  further comprising a step of cooling the seal head while the heated seal head is pressing the cap. 
     
     
         3 . A method for heat-sealing a container as defined in  claim 2  wherein cooling of the seal head is made by supplying a cooling medium into the seal head. 
     
     
         4 . A method for heat-sealing a container by sealing the container by heat welding a cap on a flange portion provided in an opening portion of the container with a seal head comprising a heating ring formed along the shape of the flange portion and a high frequency induction heating coil provided on the inside of the heating ring via magnetic shielding plates, said method comprising a step of high frequency induction heating the heating ring with the high frequency induction heating coil and pressing the cap with the heating ring to weld the cap to the container. 
     
     
         5 . A method for heat-treating a container as defined in  claim 4  wherein supply of electricity to the high frequency induction heating coil is stopped after the heating ring has been heated to a predetermined temperature and then pressing with the heating ring is continued for a predetermined period of time. 
     
     
         6 . A method for heat-treating a container as defined in  claim 4  wherein the heating ring is cooled while pressing with the heating ring is continued. 
     
     
         7 . A method for heat-sealing a container as defined in  claim 6  wherein the heating ring has a hollow portion and cooling of the heating ring is made by supplying a cooling medium into the hollow portion. 
     
     
         8 . A method for heat-sealing a container as defined in  claim 7  wherein cooling of the heating ring with the cooling medium and supplying of the cooling medium are made by providing a plurality of cooling medium supplying and exhausting openings in the hollow portion of the heating ring and supplying and exhausting the cooling medium from a different one of the supplying and exhausting openings in a predetermined order or at random. 
     
     
         9 . An apparatus for heat-sealing a container comprising a seal head for sealing the container by heat welding a cap on a flange portion provided in an opening portion of the container, said seal head comprising a seal head main body, a heat welding member provided in the seal head main body and formed in the shape of the flange portion, and a high frequency induction heating coil provided in the seal head main body for high frequency induction heating the heat welding member. 
     
     
         10 . An apparatus for heat-sealing a container as defined in  claim 9  wherein the heat welding member comprises a cooling medium flow-path which enables the heat welding member to cool while pressing of the heat welding member on the cap is maintained. 
     
     
         11 . An apparatus for heat-sealing a container as defined in  claim 9  wherein the heat welding member comprises a non-welding member on a surface of the heat welding member which presses the cap. 
     
     
         12 . An apparatus for heat-sealing a container as defined in  claim 10  wherein the heat welding member comprises cooling medium exhausting means for exhausting the cooling medium in the cooling medium flow-path after cooling of the cap. 
     
     
         13 . An apparatus for heat-sealing a container as defined in  claim 9  wherein the seal head main body comprises temperature holding means for holding heating temperature of the heat welding member. 
     
     
         14 . An apparatus for heat-sealing a container comprising a seal head and sealing the container by heating the seal head and pressing a cap placed on a flange portion of an opening portion of the container with the heated seal head to heat-weld the cap to the container, said seal head comprising a heating ring shaped along the shape of the flange portion, and a high frequency induction heating coil wound in a plurality of windings provided on the inside of the heating ring and held between magnetic shielding plates. 
     
     
         15 . An apparatus for heat-sealing a container as defined in  claim 14  wherein the heating ring of the seal head comprises a hollow portion which is a cooling medium flow-path capable of cooling the heating ring while the heating ring is pressed on the cap and a plurality of cooling medium supplying and exhausting openings provided in the cooling medium flow-path which can change a supplying and exhausting position of the cooling medium. 
     
     
         16 . An apparatus for heat-sealing a container as defined in  claim 14  wherein the heating ring comprises a non-welding member on a surface of the heating ring which presses the cap. 
     
     
         17 . An apparatus for heat-sealing a container as defined in  claim 15  wherein the heating ring comprises cooling medium exhausting means for exhausting the cooling medium in the cooling medium flow-path after cooling of the cap. 
     
     
         18 . An apparatus for heat-sealing a container as defined in  claim 14  wherein the seal head comprises temperature holding means for holding heating temperature of the heating ring. 
     
     
         19 . A method for heat-treating a container as defined in  claim 5  wherein the heating ring is cooled while pressing with the heating ring is continued. 
     
     
         20 . An apparatus for heat-sealing a container as defined in  claim 10  wherein the heat welding member comprises a non-welding member on a surface of the heat welding member which presses the cap. 
     
     
         21 . An apparatus for heat-sealing a container as defined in  claim 15  wherein the heating ring comprises a non-welding member on a surface of the heating ring which presses the cap.