Tooth rolling flat dies and method for forming teeth
AssigneeNachi-Fujikoshi Corp.
InventorsYasuhiro Murai, Takahiro Kumagai, Soiti Kakutani, Masaru Sumitani
Life of this patent
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Abstract
A tooth rolling flat die and a method for forming a tooth are provided. The die has the same service life as those of the conventional tooth rolling flat dies using oil coolant even if conducted by semi-dry forming. A first substantially quarter length portion of the leading teeth section of the die has a first surface roughness Rz of maximum height ranging from 20 to 35 μm, and a second substantially quarter length portion of the leading teeth section of the die has a second surface roughness Rz of maximum height ranging from 5 to 20 μm. The die is adapted for semi-dry forming the tooth.
Claims10
A tooth rolling flat die for forming a tooth, of the type including a spline tooth and a gear tooth, on a periphery of a cylindrical workpiece, said die having teeth sections on one working surface thereof, with the teeth sections comprising, in series, a leading teeth section wherein heights of the tops of the teeth are gradually increasing from a front edge to a rear edge of the die until a full height thereof is reached, a finishing teeth section in which each of the teeth has the full height, and a roll-off teeth section in which heights of the teeth are rapidly decreasing;
- wherein a first substantially quarter length portion of the leading teeth section has a first surface roughness Rz of maximum height ranging from 20 to 35 μm, and a second substantially quarter length portion of the leading teeth section has a second surface roughness Rz of maximum height ranging from 5 to 20 μm, so that roughness heights differ between the first and second quarter length portions.
A tooth rolling flat die for forming a tooth, of the type including a spline tooth and a gear tooth, on a periphery of a cylindrical workpiece, said die having teeth sections on one working surface thereof, with the teeth sections comprising, in series, a leading teeth section wherein heights of the tops of the teeth are gradually increasing from a front edge to a rear edge of the die until a full height thereof is reached, a finishing teeth section in which each of the teeth has the full height, and a roll-off teeth section in which heights of the teeth are rapidly decreasing;
- wherein a first substantially quarter length portion of the leading teeth section has a first surface treated by a first sandblasting treatment, and a second substantially quarter length portion of the leading teeth section has a second surface treated by a second sandblasting treatment, so that the surface roughness Rz of maximum height of the teeth of the first substantially quarter length portion of the leading teeth section is larger than the surface roughness Rz of maximum height of the teeth of the second quarter length portion.
A method for forming a tooth, of the type including a spline tooth and a gear tooth, on a periphery of a cylindrical workpiece comprising the steps of:
- providing a tooth rolling flat die having teeth sections on one working surface thereof, with the teeth sections comprising, in series, a leading teeth section wherein heights of the tops of the teeth are gradually increasing from a front edge to a rear edge of the die until a full height thereof is reached, a finishing teeth section in which each of the teeth has the full height, and a roll-off teeth section in which heights of the teeth are rapidly decreasing, wherein a first substantially quarter length portion of the leading teeth section has a first surface roughness Rz of maximum height ranging from 20 to 35 μm, and a second substantially quarter length portion of the leading teeth section has a second surface roughness Rz of maximum height of ranging from 5 to 20 μm, so that roughness heights differ between the first and second quarter portion;
- and
- forming the tooth by semi-dry forming including:
- spraying a very small amount of oil mist on the workpiece;
- and
- rolling the workpiece using the tooth rolling flat die.
Dependencies are inferred from the claim text.