Apparatus and method for sealing a container

A method for sealing a container, the method comprising:

• cutting a web of sealing material, using a linearly displaceable cutting member formed of electrically conductive material, to provide a cut portion of the sealing material;
• transferring the cut portion of sealing material to an open top of a container to be sealed by extending an independently linearly displaceable transfer member relative to the linearly displaceable cutting member, the linearly displaceable transfer member comprising an electrically insulating material;
• inductively heating the cut portion of sealing material, either directly or indirectly, to seal the cut portion of sealing material to the open top of the container whilst held against the open top of the container by the transfer member;
• wherein the step of inductively heating the cut portion of sealing material comprises producing an induction field using an induction coil and concentrating the induction field, using a field concentrator mounted on the transfer member, in a desired region away from the linearly displaceable electrically conductive cutting member to optimize the induction heating of the cut portion of sealing material.

Container sealing apparatus comprising:—

• a linearly displaceable cutting member operable to cut a portion of sealing material from a web, the linearly displaceable cutting member comprising an electrically conductive material;
• an independently linearly displaceable transfer member extendible relative to the cutting member to transfer the cut portion of sealing material from the linearly displaceable cutting member to an open top of a container to be sealed, the linearly displaceable transfer member comprising an electrically insulating material;
• an induction coil which is operable to produce an induction field for heating the cut portion of sealing material, either directly or indirectly, by induction heating to enable the cut portion of sealing material to be sealed to the open top of the container, the linearly displaceable transfer member being operable to hold the cut portion of sealing material against the open top of the container during induction heating;
• and
• a field concentrator operable to concentrate the induction field in a desired region away from the linearly displaceable electrically conductive cutting member to optimise the induction heating of the cut portion of sealing material;
• wherein the transfer member includes a transfer surface for transferring the cut portion of sealing material to the open top of the container and the field concentrator is arranged to concentrate the induction field in a region generally around the transfer surface.

Container sealing apparatus comprising:—

• a linearly displaceable cutting member operable to cut a portion of sealing material from a web, the linearly displaceable cutting member comprising an electrically conductive material;
• an independently linearly displaceable transfer member extendible relative to the cutting member to transfer the cut portion of sealing material from the linearly displaceable cutting member to an open top of a container to be sealed, the linearly displaceable transfer member comprising an electrically insulating material;
• an induction coil which is operable to produce an induction field for heating the cut portion of sealing material, either directly or indirectly, by induction heating to enable the cut portion of sealing material to be sealed to the open top of the container, the linearly displaceable transfer member being operable to hold the cut portion of sealing material against the open top of the container during induction heating;
• and
• a field concentrator operable to concentrate the induction field in a desired region away from the linearly displaceable electrically conductive cutting member to optimise the induction heating of the cut portion of sealing material;
• wherein the transfer member includes a transfer surface for transferring the cut portion of sealing material to the open top of the container and the transfer surface includes a flexible plate member to enable the transfer surface to conform generally to the shape of the open top of a container when in contact with the container in use.