Apparatus employing integral dielectric heater for roll forming thermoplastic material

Apparatus for roll forming a thermoplastic sheet material comprising:

• a first roll station, said first roll station further comprising:
• a first conductive roller and a second conductive roller, said first and second conductive rollers being rotatably mounted to a first frame means at a substantially fixed, spaced apart distance by a first and second shaft means, said second conductive roller comprising a plurality of conductive disks disposed on said second shaft transverse to an axis of rotation of said shaft, said plurality of conductive disks being spaced apart on said second shaft, said second conductive roller further comprising insulative disks disposed between adjacent ones of said plurality of conductive disks, said first roller having a first forming surface, said first forming surface having at least one angled portion, said second roller having a second forming surface, said second forming surface having a complementary angled portion, said angled portions of said first and second rollers being adapted to produce a bend in said thermoplastic sheet material when said thermoplastic sheet material is heated, said first and second forming surfaces defining a gap between said first and second rollers through which said thermoplastic sheet material is to be passed;
• and
• radio frequency generating means for application of a radio frequency electromagnetic field between said first and said second rollers, said radio frequency generating means being electrically connected to one of said first or second rollers, said electromagnetic field causing at least a portion of said thermoplastic sheet material to be heated to a softening temperature as said sheet material is passed through said electromagnetic field.

Apparatus for roll forming an elongated section of thermoplastic material comprising:

• roller means for producing at least one bend in said thermoplastic material, said roller means having forming surfaces defining a gap through which said thermoplastic material is to be passed, said roller means to be adapted to pass said thermoplastic material therethrough in a substantially continuous manner, said roller means having at least a first and second conductive portion on opposing sides of said gap at a region where said at least one bend is to be produced, said roller means comprising at least a first and a second roller, said first roller having a first forming surface extending over a portion thereof, said second roller having a second forming surface extending over a portion thereof, said rollers being spaced apart defining said gap, and wherein said first conductive portion of said roller means being located on said first forming surface and said second conductive portion of said roller means being located on said second forming surface, said second roller having a conductive shaft extending therethrough, said shaft being rotatably secured to a frame means, and said second roller comprising a plurality of alternating conductive and insulative disks oriented transversely to said shaft axis;
• and
• a radio frequency oscillator electrically connected to said conductive shaft, said radio frequency oscillator being adapted to produce a radio frequency electromagnetic field across said gap between said first and said second conductive portions of said roller means, said electromagnetic field causing a portion of said thermoplastic material exposed to said field to be heated to a softening temperature as said thermoplastic material is passed through said gap in said roller means.