Abstract: A compression coil spring includes a steel wire material containing, hereinafter in weight %, 0.5 to 0.7% of C, 1.2 to 3.0% of Si, 0.3 to 1.2% of Mn, 0.5 to 1.9% of Cr and 0.05 to 0.5% of V as necessary components, one or more kinds selected from not more than 1.5% of Ni, not more than 1.5% of Mo and not more than 0.5% of W as freely selected components, and iron and inevitable impurities as the remainder; the C-condensed layer which exceeds the average concentration of C contained in the steel wire material exists at a surface layer part, and the thickness of the C-condensed layer is within 0.01 to 0.05 mm along the entire circumference of the steel wire material.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A spring forming device in which the steel wire can be continuously cut off without stopping the feeding of the steel wire in cutting, and in which the steel wire can be uniformly heated, is provided. The spring forming device has a wire supplying mechanism for supplying a steel wire using a plurality of feeding rollers, a heating mechanism for heating the steel wire, a coiling mechanism for forming in a coil state the heated steel wire, and a cutting mechanism for cutting the steel wire coiled at a given number of turns off the steel wire remained backward. A cutting blade of the cutting mechanism follows tracks having a speed Va that moves to the receiving blade and a speed Vc that moves in an axial direction of the coiled steel wire, in cutting of the steel wire.

Abstract: A titanium alloy member with high strength and high proof stress not only in the surface but also inside, using a general and inexpensive ?-? 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.

Abstract: 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.

Abstract: 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.

Abstract: A spring forming device in which the steel wire can be continuously cut off without stopping the feeding of the steel wire in cutting, and in which the steel wire can be uniformly heated, is provided. The spring forming device has a wire supplying mechanism for supplying a steel wire using a plurality of feeding rollers, a heating mechanism for heating the steel wire, a coiling mechanism for forming in a coil state the heated steel wire, and a cutting mechanism for cutting the steel wire coiled at a given number of turns off the steel wire remained backward. A cutting blade of the cutting mechanism follows tracks having a speed Va that moves to the receiving blade and a speed Vc that moves in an axial direction of the coiled steel wire, in cutting of the steel wire.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A titanium alloy member with high strength and high proof stress not only in the surface but also inside, using a general and inexpensive ?-? 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.

Abstract: A high-strength magnesium alloy wire rod suitable for products in which at least one of bending stress and twisting stress primarily acts is provided. The wire rod has required elongation and 0.2% proof stress, whereby strength and formability are superior, and has higher strength in the vicinity of the surface. In the wire rod, the surface portion has the highest hardness in a cross section of the wire rod, the highest hardness is 170 HV or more, and the inner portion has a 0.2% proof stress of 550 MPa or more and an elongation of 5% or more.

Abstract: 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.

Abstract: When a cylinder block is cast, a bearing housing is constituted by a preform integrally cast with the cylinder block. In order to raise the strength of the bearing housing, a metal matrix composite is formed around the preform. The preform is constituted by a high volume factor member having a relatively high volume factor and two low volume factor members having a relatively low volume factor connected with top and under surfaces of the high volume factor member respectively. The high volume factor member is made of solid metal and the low volume factor member is made of sintered metal filaments. Base material of the cylinder block infiltrates into the low volume factor member to form a metal matrix composite in the preform.

Abstract: A structure of bearing housings of a cylinder block comprises aluminum alloy for constituting the whole cylinder block and a plurality of fiber reinforced metal (FRM) areas. The FRM areas are formed by integrally casting a sheet-like preform containing reinforced metal fibers with aluminum alloy. A plurality of such sheet-like preforms are separately provided in a bearing housing in an axial direction of a crankshaft.

Abstract: A structure of bearing housings of a cylinder block comprises aluminum alloy for constituting the whole cylinder block and a plurality of fiber reinforced metal (FRM) areas.

Abstract: A part of a piston is composed of a metal matrix composite. The metal matrix composite is composed of a matrix of a light metal alloy and reinforcements formed of metallic fibers mixed in the matrix. The reinforcements are formed of an alloy that consists mainly of Fe and Cr and contains Al and/or Si. The Cr content and the Al and/or Si content of the reinforcements range from 5 to 30% and from 3 to 10%, respectively. The fiber diameter of the reinforcements ranges from &phgr;20 &mgr;m to &phgr;100 &mgr;m. The reinforcements are formed by the melt extraction method and have irregular peripheral surfaces. Solution-treatment of the metal matrix composite is carried out within a temperature range from 470° C. to 500° C. such that formation of intermetallic compounds is restrained.