Toroidal electrical transformer and method of producing same

An apparatus for winding an annular magnetic core for an electrical transformer substantially from a continuous strip of magnetic material, said electrical transformer including coil means having arcuate elongated passage means extending therethrough being at least three fourths of a complete annular toroidal passage and leaving a circumferentially-extending gap means communicating with said arcuate elongated passage means, said apparatus including a belt means forming a loop which enters said arcuate elongated passage means through said gap means and egresses said arcuate elongated passage means through said gap means, said apparatus further including drive means for driving said belt means and feed means for feeding said continuous strip of magnetic material through said gap means so as to engage said belt means to wind said magnetic material in place within said arcuate elongated passage means to form said annular magnetic core as said belt means is driven by said drive means, said feed means includes guide means for axially aligning said strip of magnetic material as it is fed through said gap means, said belt means engaging the radially-outward winding of said annular magnetic core as it is being wound within said arcuate elongated passage means, said drive means being adapted to drive said belt means until said annular magnetic core is fully wound within said arcuate elongated passage means, said guide means includes at least one roller engaging the rotating edge of said annular magnetic core as it is being wound within said arcuate elongated passage means and also engaging the edge of said strip of magnetic material as it is fed through said gap means, said roller being frusto-conical in shape and extending in a generally radial direction along the edge of said annular magnetic core with its smaller end oriented toward the center of the magnetic core, whereby the surface speed of said frusto-conical roller substantially equals the rotational speed of the edge of said annular magnetic core.