Patent ID: 6657165
Filing Date: 2003-12-02
Classification: B29C,B29L,B31B,H05B

Abstract:
A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web; each seal forming element has an outer section on which is located at least one electrical heater, an inner section which contains the sealing wheel and an intermediate section which includes thermal insulation which insulates the outer section from the inner section; and wherein each electrical heater is comprised of an electrical resistance disposed along a longitudinal dimension of the outer section of the seal forming element, the electrical resistance being distributed along the longitudinal dimension with a higher electric resistance being adjacent to a part of the intermediate section through which heat flows to the inner section and a lower electrical resistance which is disposed adjacent to the thermal insulation of the intermediate section.