Heat pad

A heat pad for pressing against a curved surface of an annular tire to vulcanize a tire patch comprising a channel-shaped sheet member of resilient conductive rubber material having spaced-apart elongated side edges and U-shaped end edges, a first electrode adhered to said sheet member at a position adjacent one of said side edges, a second electrode adhered to said sheet member at a position adjacent the other of said side edges, a cover member of resilient insulating rubber material encasing said sheet member of resilient conductive rubber material having side edges spaced outwardly of said elongated side edges of said U-shaped end edges of said sheet member and said cover member having U-shaped end edges spaced outwardly of said end edges of said sheet member, said cover member further comprising a first layer and a second layer of resilient insulating rubber material having edges coincident with said side edges and U-shaped end edges of said cover member, said first layer overlapping and being adhered to a first side of said sheet member of resilient conductive rubber material, said second layer overlapping and being adhered to a second side opposite said first side of said sheet member and being adhered to overlapped portions of said first layer of resilient insulating rubber material, and wires positioned between said first layer and said second layer in said overlapped portions at the U-shaped end edges of said insulating rubber material, said wires connecting said first electrode and said second electrode to a source of electricity to heat said sheet member of resilient conductive rubber material, said heat pad having an intermediate portion between said first electrode and said second electrode for pressing against said curved surface of said annular tire and said intermediate portion being stretchable in a direction radially of said tire and in a direction circumferentially of said tire to conform to said curved surface of said tire under pressure from a pressing member urging said heat pad against said tire.