BALL SCREW, METHOD FOR MANUFACTURING THE SAME, POWER STEERING DEVICE, AND METHOD FOR MANUFACTURING THE SAME

• Main Authors: SHIINO KOTARO, NUMAKURA KOJI, KOMURO MATAHIRO, TSUJIMI SHINTARO, HATO HISAMITSU
• Format: Patent
• Language: English; Japanese
• Published: 17.09.2020
• Subjects: BLASTING; CHEMISTRY; ENGINEERING ELEMENTS AND UNITS; GEARING; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS; LIGHTING; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL ENGINEERING; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; MOTOR VEHICLES; PERFORMING OPERATIONS; THERMAL INSULATION IN GENERAL; TRAILERS; TRANSPORTING; WEAPONS

To provide a ball screw in which a screw shaft and a nut have the structures satisfying required performance and which improves durability, and provide a manufacturing method therefor, a power steering device, and a method for manufacturing the same.SOLUTION: A ball screw of the present invention has a nut made of a steel base material which has a female screw formed on the inner peripheral surface, a screw shaft combined with the nut and made of a steel base material which has a male screw formed on the outer peripheral surface to face the female screw, and a plurality of balls disposed between the female screw and the male screw. The surface of the nut, which comes in contact with the balls, and the surface of the screw shaft, which comes in contact with the balls, have carburized layers, and the carbon concentration in the carburized layer of the nut is higher than the carbon concentration in the carburized layer of the screw shaft.SELECTED DRAWING: Figure 3 【課題】ねじ軸およびナットが要求される性能を満たす組織を有し、耐久性を向上したボールネジおよび製造方法ならびにパワーステアリング装置およびその製造方法を提供する。【解決手段】本発明のボールネジは、内周面に雌ねじが形成された鋼製の基材からなるナットと、ナットに組み合わされ、外周面に前記雌ねじに対向する雄ねじが形成された鋼製の基材からなるねじ軸と、雌ねじと雄ねじとの間に配置された複数個のボールと、を有し、ナットのボールと接触する面およびねじ軸のボールと接触する面は浸炭層を有し、ナットの浸炭層における炭素濃度が、ねじ軸の前記浸炭層の炭素濃度よりも高いことを特徴とする。【選択図】図３