Worm wheel, power steering apparatus including the worm wheel, and method of forming the worm wheel

A worm wheel comprising:

• an annular worm wheel main body comprising a resin material;
• and
• teeth on an outer periphery of the annular worm wheel main body in a circumferential direction of the annular worm wheel main body, the teeth comprising tooth flanks configured to be brought into meshing engagement with a worm shaft, a tooth crest on an outer peripheral surface of each of the teeth, and a tooth bottom between each adjacent pair of the tooth flanks that face each other in the circumferential direction of the annular worm wheel main body;
• a first region on each of the tooth flanks, the first region being offset from a mid-position of a whole depth of each of the teeth in a radially outward direction of the annular worm wheel main body, the first region in at least one end portion of each of the tooth flanks in an axial direction of the annular worm wheel main body, the first region configured to form a predetermined clearance between the first region in the at least one end portion of each of the tooth flanks and the worm shaft when the worm wheel and the worm shaft are in meshing engagement with each other;
• and
• a second region on each of the tooth flanks, the second region being a cut-out portion,
• wherein the first region is in a portion of each of the tooth flanks that is on a radial outside of a pitch circle.