Patent ID: 7258209

Claim:
A brake drum for use in a drum brake comprising: an extruded cylindrical friction member with an outer periphery having a plurality of axial projecting portions, said projecting portions extending along an entire width of said friction member and being formed at uniform intervals in a circumferential direction around the outer periphery of the friction member; a drum body molded around the outer periphery of said friction member, said drum body being formed of an aluminum alloy, wherein each of the projecting portions has a projecting height in a range of 0.5–3.0 mm, said height being generally uniform on each individual projecting portion along the width of the friction member; and, wherein said friction member is formed of an aluminum-base composite material produced by causing a reinforcing material of metal oxide to be contacted and reduced by magnesium nitride such that at least part of the reinforcing material is exposed as a metal part, and thereafter causing aluminum alloy to penetrate into the reinforcing material, whereby the so-produced aluminum base composite material has extensibility characteristics that permit subsequent simultaneous extrusion of said friction member with said projecting portions.