Electrically heated apparatus employing a PTC heater for liquifying a rod of binding material

摘要

An apparatus for liquifying a rod of binding by application of heat includes a die-cast aluminum heating member having an elongated conical first channel decreasing in diameter from an inlet adapted to receive a rod of liquifiable bonding material through an elastic funnel surrounding the inlet to an outlet for discharging liquified material through a one-way valve. An electric heater is disposed in a second channel in said member parallel to the first channel and includes an elongated electrically insulating and elastic housing defining a cylindrical cartridge receiving at least one flat PTC resistor disposed between at least a pair of pressure bodies in the housing on opposite sides of the least one PTC resistor. At least one elongated, curved leaf spring is disposed between one of the pressure bodies and at least one PTC resistor for applying pressure to the bodies and the at least one PTC resistor to maintain constant contact pressure therebetween even under thermal expansion and contraction.