Worm wheel of steering system speed reducer, and manufacturing method therefor

A worm wheel of a steering device reducer, comprising:

• an outer toothed part having a ring shape provided with outer gear teeth engaged with gear teeth of a worm shaft on an outer circumferential side thereof and insertion recesses radially depressed and circumferentially spaced apart from each other on an inner circumferential side thereof and having at least one coupling hole in at least one of an upper surface and lower surface thereof;
• an inner toothed part having a ring shape inserted into an inside of the outer toothed part and provided with insertion protrusions fitted into the insertion recesses, on an outer circumferential side thereof and at least one cylindrical coupling protrusion protruding from at least one of an upper surface and lower surface of the inner toothed part in an axial direction and a position corresponding to the at least one coupling hole to be coupled to the at least one coupling hole;
• a hub to which a steering shaft is coupled;
• and
• a boss part provided between an outer circumferential side of the hub and an inner circumferential side of the outer toothed part,
• wherein the at least one coupling hole is formed in an arc shape, wherein the at least one coupling hole comprises a plurality of coupling holes arranged on the upper surface or lower surface to be spaced apart from each other, and wherein the at least one coupling protrusion is formed to protrude in an arc shape corresponding to the at least one coupling hole.

A method for manufacturing a worm wheel of a steering device, the method comprising:

• providing an outer toothed part having a ring shape provided with outer gear teeth engaged with gear teeth of a worm shaft on an outer circumferential side thereof and insertion recesses radially depressed and circumferentially spaced apart from each other on an inner circumferential side thereof and having at least one coupling hole in at least one of an upper surface and lower surface thereof;
• providing an inner toothed part having a ring shape inserted into an inside of the outer toothed part and provided with insertion protrusions fitted into the insertion recesses, on an outer circumferential side thereof and at least one cylindrical coupling protrusion protruding from at least one of an upper surface and lower surface of the inner toothed part in an axial direction and a position corresponding to the at least one coupling hole to be coupled to the at least one coupling hole;
• coupling a steering shaft to a hub;
• and
• providing a boss part between an outer circumferential side of the hub and an inner circumferential side of the outer toothed part,
• wherein the at least one coupling hole is formed in an arc shape, wherein the at least one coupling hole comprises a plurality of coupling holes arranged on the upper surface or lower surface to be spaced apart from each other, and wherein the at least one coupling protrusion is formed to protrude in an arc shape corresponding to the at least one coupling hole.