Nhk Spring Co., Ltd.

Tohoku University

Other

Kobayashi Pharmaceutical Co., Ltd.

Nhk Co., Ltd.

Yoshiki Ono

Takeshi Suzuki

Tohru Shiraishi

Akihiko Chiba

Yuji Araoka

Shimpei Kurokawa

Masashi Sakamoto

Yohei Kameda

Hiroaki Matsumoto

Sang-Hak Lee

Kazuya Ikai

Shigemi Sato

Kazuhisa Matsumoto

Akira Yamazaki

Keita Takahashi

Kazuo Iwata

Michihiko Ayada

Tatsuya Kurihara

Kazuhiko Konomi

Morimichi Kai

Masaru Imamura

Yuichiro Ono

Takamichi Sano

Yuitirou Ono

Toshiaki Maruichi

Kosuke Shibairi

Yoichi Nishio

Kenichi Omori

Sumikazu Oki

A spring consists of, by mass %, 0.5 to 0.7% of C, 1.0 to 2.0% of Si, 0.1 to 1.0% of Mn, 0.1 to 1.0% of Cr, not more than 0.035% of P, not more than 0.035% of S, and the balance of Fe and inevitable impurities. The spring has a structure including not less than 65% of bainite and 4 to 13% of residual austenite by area ratio in a cross section. The spring has a compressive residual stress layer in a cross section from a surface to a depth of 0.35 mm to D/4, in which D (mm) is a circle-equivalent diameter of the cross section. The spring has a high hardness layer with greater hardness than a center portion by 50 to 500 HV from a surface to a depth of 0.05 to 0.3 mm.

Spring and manufacture method thereof

The coil spring according to the present invention is a coil spring that is formed by spirally winding a wire rod and that includes a core that is elastically deformable and a reinforced fiber layer including reinforcing fibers wound around an outer circumference of the core and a thermoset resin that firmly adheres the reinforcing fibers to one another, wherein, in at least a part of a surface layer of the reinforced fiber layer, a content percentage of the reinforcing fibers on an inner circumferential side of the coil spring is larger than a content percentage of the reinforcing fibers on an outer circumferential side of the coil spring.

Coil spring

A compression coil spring having high durability can be provided by using an inexpensive wire material. The present invention provides a compression coil spring formed by using a steel wire material, the steel wire material made of C: 0.45 to 0.85 mass %, Si: 0.15 to 2.5 mass %, Mn: 0.3 to 1.0 mass %, Fe and inevitable impurities as a remainder, and a circle-equivalent diameter of 1.5 to 9.0 mm, wherein hardness of a freely selected cross-section of the wire material is 570 to 700 HV, and at an inner diameter side of the coil spring, unloaded compressive residual stress at a depth of 0.2 mm from a surface in an approximate maximal main stress direction in a case in which compressive load is loaded on the spring is 200 MPa or more, and unloaded compressive residual stress at a depth of 0.4 mm from surface is 100 MPa or more.

Compression coil spring and method for producing same

A high strength titanium alloy member with superior fatigue resistance, and a production method therefor, are provided. The production method includes preparing a raw material made of titanium alloy, nitriding the raw material to form a nitrogen-containing raw material by generating a nitrogen compound layer and/or a nitrogen solid solution layer in a surface layer of the raw material, mixing the raw material and the nitrogen-containing raw material to yield a nitrogen-containing mixed material, sintering the nitrogen-containing mixed material to obtain a sintered titanium alloy member by bonding the material together and uniformly diffusing nitrogen in solid solution from the nitrogen-containing raw material to the entire interior portion of the sintered titanium alloy member, hot plastic forming and/or heat treating the sintered titanium alloy member to obtain a processed member, and surface treating the processed member to provide compressive residual stress.

Titanium alloy member and production method therefor

A production method for a titanium alloy member includes preparing a titanium alloy material for sintering as a raw material of a sintered body; nitriding the titanium alloy material for sintering, thereby forming a nitrogen compound layer and/or a nitrogen solid solution layer in a surface layer of the titanium alloy material for sintering and yielding a nitrogen-containing titanium alloy material for sintering; mixing the titanium alloy material for sintering and the nitrogen-containing titanium alloy material for sintering, thereby yielding a titanium alloy material for sintering mixed with nitrogen-containing titanium alloy material; sintering the titanium alloy material for sintering mixed with nitrogen-containing titanium alloy material, thereby bonding the material each other and dispersing nitrogen contained in the nitrogen-containing titanium alloy material for sintering in a condition in which nitrogen is uniformly dispersed into an entire inner portion of the sintered body by solid solution.

High-strength titanium alloy member and production method for same

Rotor core plate for electric motor

A high-strength magnesium alloy member is suitable for products in which at least one of bending stress and twisting stress primarily acts. The member has required elongation and 0.2% proof stress, whereby strength and formability are superior, and has higher strength and large compressive residual stress in the vicinity of the surface of a wire rod. In the magnesium alloy member formed as a wire rod in which at least one of bending stress and twisting stress primarily acts, the wire rod includes a surface portion having the highest hardness of 170 HV or more in the vicinity of the surface and an inner portion having a 0.2% proof stress of 550 MPa or more and an elongation of 5% or more, and the wire rod has the highest compressive residue stress in the vicinity of the surface of 50 MPa or more.

Magnesium alloy member and production method therefor

A titanium alloy member with high strength and high proof stress not only in the surface but also inside, using a general and inexpensive &#x3b1;-&#x3b2; type titanium alloy, and a production method therefor, are provided. The production method includes preparing a raw material made of titanium alloy, nitriding the raw material to form a nitrogen-containing raw material by generating a nitrogen compound layer and/or a nitrogen solid solution layer in a surface layer of the raw material, mixing the raw material and the nitrogen-containing raw material to yield a nitrogen-containing mixed material, sintering the nitrogen-containing mixed material to obtain a sintered titanium alloy member by bonding the material together and uniformly diffusing nitrogen in solid solution from the nitrogen-containing raw material to the entire interior portion of the sintered titanium alloy member, and hot plastic forming the sintered titanium alloy member.

The present invention provides an &#x3b1;+&#x3b2; type titanium alloy and a production method therefor, which has an ultrafine structure causing superplasticity under low temperatures and has a high deformation ratio compared to conventional &#x3b1;+&#x3b2; type Ti alloys. The alloy has an ultrafine structure made of equiaxial crystals in which an area ratio of crystals having a grain diameter of 1 &#x3bc;m or less is 60% or more, and maximum frequency grain diameter is 0.5 &#x3bc;m or less, wherein a portion in which the integration degree of plane orientation of the hexagonal close-packed crystal is 1.00 or more exists within a range of 0 to 60 degrees with respect to a normal line of a processed surface of the alloy.

&#x3b1;+&#x3b2; type titanium alloy and production method therefor

The coil spring includes steel wire material containing 0.45 to 0.80 weight % of C, 0.15 to 2.50 weight % of Si, 0.3 to 1.0 weight % of Mn and iron and inevitable impurities as the remainder, and having a circle equivalent diameter of 2.5 mm to 10 mm, in which internal hardness at a freely selected cross section of the wire material is in a range of 570 to 700 Hv, C-condensed layer which exceeds average concentration of C contained in the steel wire material exists at surface layer part, and in an approximate maximum principal stress direction generated when a compressive load is loaded on spring of inner diameter side of the coil spring of the wire material, unloaded compressive residual stress at a depth of 0.2 mm and 0.4 min from surface of the wire material is not less than 200 MPa and not less than 60 MPa, respectively.

Helical compression spring and method for manufacturing same

An alloy having an &#x3b1;' martensite which is a processing starting structure is hot worked. The alloy is heated at a temperature increase rate of 50 to 800&#xb0; C./sec, and strain is given at not less than 0.5 by a processing strain rate of from 0.01 to 10/sec in a case of a temperature range of 700 to 800&#xb0; C., or by a processing strain rate of 0.1 to 10/sec in a case of a temperature range of 800&#xb0; C. to 1000&#xb0; C. By generating equiaxial crystals having average crystal particle diameters of less than 1000 nm through the above processes, a titanium alloy having high strength and high fatigue resistant property can be obtained, in which hardness is less than 400 HV, tensile strength is not less than 1200 MPa, and static strength and dynamic strength are superior.

Nanocrystal-containing titanium alloy and production method therefor

A magnet plate used for a rotor core of a motor, includes a magnetic pole portion being set between an outer peripheral edge of a body portion and a magnet slot and having a radial width being smaller than a radial sectional width of the permanent magnet, and a higher hardness portion being formed into a hook shape along an end corner of the magnet slot and have a smaller width than the radial sectional width of the permanent magnet.

Magnetic plate used for rotor core of motor and method for manufacturing magnetic plate

A surface treatment method for a steel material includes carbonitriding, quenching, and tempering. The steel material consists of, by weight %, 0.27 to 0.48% of C, 0.01 to 2.2% of Si, 0.30 to 1.0% of Mn, not more than 0.035% of P, not more than 0.035% of S, and the balance of Fe and inevitable impurities. The carbonitriding step is performed by heating the steel at a temperature of not less than the Apoint and not more than 1100&#xb0; C. and bringing the steel into contact with a mixed gas atmosphere so as to concentrate nitrogen and carbon at a surface layer of the steel. The quenching step is performed by cooling the steel to room temperature at a rate of not less than 20&#xb0; C./second. The tempering step is performed by heating the steel at a temperature of 100 to 400&#xb0; C.

Spring steel and surface treatment method for steel material

A spring with superior fatigue resistance is provided by decreasing the material cost while simplifying the production process. Disclosed is a spring including: a composition consisting of, by mass %, 0.5 to 0.7% of C, 1.0 to 2.0% of Si, 0.1 to 1.0% of Mn, 0.1 to 1.0% of Cr, not more than 0.035% of P, not more than 0.035% of S, and the balance of Fe and impurities; a structure including not less than 95% of tempered martensitic structure; a compressive residual stress layer formed to a depth of 0.35 mm to D/4, in which D (mm) is a diameter; the compressive residual stress layer having maximum compressive residual stress of 800 to 2000 MPa; a center portion with Vickers hardness of 550 to 700 HV; and a high hardness layer with greater hardness than the center portion.

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Yokohama, Japan

Yoshiki Ono