Abstract: The side seam of a can is coated and heated inductively by passing it through a medium frequency, oscillating magnetic field generated by an induction coil wound around a core. The core is shaped and oriented so as to have two magnetically opposite poles direct magnetic flux in a concentrated manner from the coil into the side seams of cans traveling along a path of travel. The cores are constructed using individual laminations of high frequency core material, each less than about 0.006 inches thick, individually insulated from each other and bound together to form a U- or E-shaped core directing flux toward the workpiece. The induction coil is constructed using a form of Litz wire and the coil and core are air-cooled. In one embodiment, the core has a plurality of pole pieces each directed toward the path of travel. The induction coil is wound on the core such that sequential ones of the pole pieces along the path of travel have alternatingly magnetically opposite polarities.

Abstract: A method and apparatus for 360.degree. induction heating of a can body to cure or partially cure a protective coating applied thereto. The can bodies are inductively heated by placing them in a medium frequency, oscillating magnetic field generated by a multiple turn induction coil helically wound around the transport path of the can body. By using a medium-frequency field and by centering the can bodies with respect to the induction coil, the can bodies may be evenly and uniformly heated around 360.degree. of their circumference.

Abstract: Apparatus for inductively heating metal can lids operates at medium frequency, with a many-turn induction coil wrapped partly or entirely around the can closures. No focusing cores are required, nor need the conductors be water cooled. Can ends may be fed through the apparatus in-stick. IGBTs are used in the H-bridge of the inverter. A control system is also provided which minimizes peak current flow through the switches and obviates the need for a series inductor conventionally used for current limiting. The control system monitors the tank voltage phase angle and turns the switches on and off in optimal response thereto. Can lids are separated magnetically while being motivated by sequentially switched electromagnets, and can bodies may be rotated by a split conveyor belt while being transported through inductive heating apparatus.

Abstract: Apparatus for spacing a plurality of substantially plate-like ferromagnetic workpieces such as can lids, in face-to-face relationship along a row, comprises a plurality of magnetic elements, each extending longitudinally along the row and different ones of the elements being disposed at different angular positions around the row, each of the magnetic elements being disposed and oriented to prevent the workpieces from pivoting about a distal edge of the workpiece due to the combined magnetic attraction of the workpiece by all others of the magnetic elements.

Abstract: A dryer apparatus and a drying method are set forth for drying an object coated with a solvent which volatilizes to form a VOC. The object is fed through an enclosure. It is heated to volatilize the VOC while it is in the enclosure. A catalytic oxidation unit is provided which oxidizes substantially all VOCs which flow through it. A VOC containing first gas from the enclosure is introduced to an upstream end of a catalytic oxidation zone in the catalytic oxidation unit. A substantially VOC free second gas is led away from a downstream end of the catalytic oxidation zone. Heat is exchanged between the hot second gas and the first gas. The first gas is pumped from a first location in the enclosure and impelled into and through the oxidation unit. A sufficient portion of the second gas is impelled into the surrounding atmosphere to maintain a pressure below that of the surrounding atmosphere within both the oxidation unit and the dryer enclosure.