Nut, female thread machining device and female thread machining method
AssigneeHonda Motor Co., Ltd.
InventorsYota Eguchi, Hiroki Fujiuchi, Naoki Takahashi, Toshihiro Murakawa
Life of this patent
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Abstract
There is provided a nut having a thread portion having a female thread, a metallic plate portion having a base segment, and a hardness gradient portion provided between the thread portion and the metallic plate portion. The thread portion, metallic plate portion and the hardness gradient portion are monolithic each other, a metallographic structure of the metallic plate portion differs from a metallographic structure of the thread portion and a hardness of the hardness gradient portion is lower than a hardness of the thread portion and lowers from the thread portion toward the metallic plate portion.
Claims12
A female thread machining device comprising:
- a heating unit which heats a region where a female thread is to be formed in a metallic workpiece including a metallic plate;
- a machining tool which forms the female thread in the metallic workpiece;
- a chuck that detachably holds the machining tool;
- a rotation-driving unit which rotates the machining tool;
- an advance/retract driving unit which advances or retracts the machining tool;
- a rotating rod that extends between the rotation-driving unit and the chuck;
- and
- a cooling unit adapted to discharge fluid onto the rotating rod at a position between the chuck and the rotation-driving unit so as to cool the machining tool.
A female thread machining method comprising:
- a heating step of, by a heating unit, heating a region of a metallic workpiece including a metallic plate where a female thread is formed to an austenitizing temperature or higher;
- a cooling step of cooling a machining tool, which is adapted to form the female thread in the metallic workpiece, by a cooling unit;
- a machining step comprising:
- stopping heating the metallic workpiece by the heating unit and continuing cooling the machining tool by the cooling unit;
- inserting the machining tool into the metallic workpiece while rotating the machining tool;
- and
- forming the female thread by the machining tool while cooling the metallic workpiece by the machining tool;
- and
- a heat-radiating step of cooling the metallic workpiece after the machining step so that a metallographic structure of a portion of the metallic workpiece is changed to a bainite structure.
Dependencies are inferred from the claim text.