Abstract: A bolt has a male screw with a surface hardening portion that has an increased surface hardness and that is applied with a compressive residual stress. The male screw is formed by cutting the bolt, and performing a process to provide at least on the surface of the male screw of the bolt the surface hardening portion that has increased hardness and that is applied with a compressive residual stress. As a result, the fatigue resistance of the male screw is improved and the bolt is effective for use in a portion where the male screw is subject to a repetitive stress.

Abstract: A system calculates axial deformation of a turbine rotor. The system includes an input part that sets measurement points of rotor disks that constitute the turbine rotor; a deflection amount detection part that derives radial displacement amounts of the turbine rotor for at least four or more measurement points along an outer surface in a circumferential direction of the turbine rotor based on measured values measured by a displacement gage; a storage part that stores the radial displacement amounts and measured angles at the measurement points; and a calculation part that calculates misalignment data of a most probable circle of the turbine rotor based on data stored. The calculated circle is calculated from the displacement amount and the measured angles. The most probable circle is determined from the calculated circle, and the misalignment data of the most probable circle is calculated from the most probable circle.

Abstract: In a method of calculating misalignment of a rotational body, radial displacement values are measured using a displacement gauge. A calculation part performs the steps of deriving radial displacement amounts of the rotational body for at least four or more measurement points along an outer surface while rotating the rotational body, selecting three arbitrary points to calculate a circle, calculating circle values for all the measurement points, calculating differences between the calculated circle values and the radial displacement amounts as error amounts, summing the error amounts to derive a total error amount, repeating circle calculation for different combinations and calculating a total error amount for each calculated circle, selecting a circle with a minimum total error amount as a most probable circle, and calculating deviation between the center of the most probable circle and the center of rotation of the rotational body.

Abstract: A bolt has a male screw with a surface hardening portion that has an increased surface hardness and that is applied with a compressive residual stress. The male screw is formed by cutting the bolt, and performing a process to provide at least on the surface of the male screw of the bolt the surface hardening portion that has increased hardness and that is applied with a compressive residual stress. As a result, the fatigue resistance of the male screw is improved and the bolt is effective for use in a portion where the male screw is subject to a repetitive stress.

Abstract: A system and method for calculating misalignment of a rotational body includes: deriving radial displacement amounts of the rotational body for at least four or more measurement points; selecting three arbitrary points among all the measurement points to calculate a circle; calculating circle values for all the measurement points from the calculated circle; calculating differences between the calculated circle values and the radial displacement amounts as error amounts at the measurement points; summing the error amounts to derive a total error amount value; repeating calculation for combinations of three measurement points to calculate each total error amount value; selecting a calculated circle with a minimum total error amount value as a most probable circle; and calculating deviation between the center of the most probable circle and the center of rotation of the rotational body as misalignment data of the most probable circle.

Abstract: A system calculates axial deformation of a turbine rotor. The system includes: an input part that sets measurement points of a rotor disk that constitutes the turbine rotor; a deflection amount detection part that derives radial displacement amounts of the turbine rotor for at least four or more measurement points along an outer surface in a circumferential direction of the turbine rotor based on measured values measured by a displacement gage; a storage part that stores the radial displacement amounts derived by the deflection amount detection part and measured angles at the measurement points; and a calculation part that calculates misalignment data of a most probable circle of the turbine rotor based on data stored in the storage part. At least four or more measurement points are set in the circumferential direction of the turbine rotor. The calculated circle is calculated from the displacement amount and the measured angle measured at each measurement point.

Abstract: The present invention provides a surface hardening portion 11 that has increased surface hardness and that is applied with a compressive residual stress, at least on the surface of a male screw 10 of a bolt 1. The present invention includes the steps of cutting to form the male screw 10 of the bolt 1, and processing to provide at least on the surface of the male screw 10 of the bolt 1 the surface hardening portion 11 that has increased hardness and that is applied with a compressive residual stress. As a result, the present invention can improve the fatigue resistance of the male screw 10 and the bolt is effective as a bolt to be used in a portion where the male screw 10 is subject to a repetitive stress.

Abstract: A method of manufacturing a golf ball is disclosed. A cover is molded through use of either a thermoplastic resin having a group capable of reacting with an isocyanate group or a thermoplastic resin containing a compound having two or more groups capable of reacting with an isocyanate group. Subsequently, a polyisocyanate compound is caused to permeate into the surface layer of the cover to thereby cause the reaction between the polyisocyanate compound and the group(s) capable of reacting with the isocyanate group. As a result, a modified layer having excellent properties is formed at the surface of the cover formed from thermoplastic resin. In this case, a non-yellowing polyurethane resin is preferably used as the thermoplastic resin having a group capable of reacting with an isocyanate group, and 4,4-diphenylmethane diisocyanate (MDI) is preferably used as the polyisocyanate compound.

Abstract: Disclosed is a golf ball including: a plurality of dimples arranged overall on the spherical surface of the golf ball by assuming the spherical surface of the golf ball as a spherical octahedron and using, as dimple arrangement units, eight spherical triangles constituting the spherical octahedron, on each of which a specific number of the dimples are arranged. In this golf ball, at least the four dimples are arranged on each of three sides of the spherical triangle; there is no great circle with which none of the dimples intersects; and the total number of the dimples is in a range of 380 to 450.

Abstract: Using a mold having typically two split mold segments which are mated in a separable manner to define a spherical mold cavity therein, a golf ball having a multiplicity of dimples in its surface is molded by feeding a molding material into the mold cavity. The mold is split along a line off a horizontal great circle of the golf ball into two split mold segments having different areas of contact with the ball. The golf ball as molded is always caught and left in the larger mold segment and thus can be easily removed from the mold by a routine operation.

Abstract: A method of manufacturing a golf ball is disclosed. A cover is molded through use of either a thermoplastic resin having a group capable of reacting with an isocyanate group or a thermoplastic resin containing a compound having two or more groups capable of reacting with an isocyanate group. Subsequently, a polyisocyanate compound is caused to permeate into the surface layer of the cover to thereby cause the reaction between the polyisocyanate compound and the group(s) capable of reacting with the isocyanate group. As a result, a modified layer having excellent properties is formed at the surface of the cover formed from thermoplastic resin. In this case, a non-yellowing polyurethane resin is preferably used as the thermoplastic resin having a group capable of reacting with an isocyanate group, and 4,4-diphenylmethane diisocyanate (MDI) is preferably used as the polyisocyanate compound.

Abstract: A golf ball has a core and a cover and, the cover includes at least one thin spherical layer with a thickness of not more than 1.5 mm. The thin layer is molded by injecting an injection molding material at a selected fill speed which is correlated to the melt flow rate of the molding material. The invention facilitates the mass production of golf balls having thin spherical cover layers of uniform thickness which offer potential for further improvements in ball performance.

Abstract: A method of manufacturing a golf ball is disclosed. A cover is molded through use of either a thermoplastic resin having a group capable of reacting with an isocyanate group or a thermoplastic resin containing a compound having two or more groups capable of reacting with an isocyanate group. Subsequently, a polyisocyanate compound is caused to permeate into the surface layer of the cover to thereby cause the reaction between the polyisocyanate compound and the group(s) capable of reacting with the isocyanate group. As a result, a modified layer having excellent properties is formed at the surface of the cover formed from thermoplastic resin. In this case, a non-yellowing polyurethane resin is preferably used as the thermoplastic resin having a group capable of reacting with an isocyanate group, and 4,4-diphenylmethane diisocyanate (MDI) is preferably used as the polyisocyanate compound.

Abstract: In a dimpled golf ball, the parameters of dimples are optimized to improve the aerodynamic performance of the ball and thus increase its flight distance. The dimples have a planar shape which is circular, and are of at least three types of mutually differing diameter. At least one of the types of dimples has a cross-sectional shape differing from that of the other types. One of the dimple types may have a cross-sectional shape defined by the union of at least two concave portions of differing slope.

Abstract: A golf ball includes a large number of two types pr more dimples different in diameter and/or depth, which are arranged on the surface of the golf ball; wherein an EAstdev value of the golf ball is in a range of 2 or less, the EAstdev value being expressed by the following equations: EA ⁡ ( α j ) = ∑ i = 1 N ⁢ [ S ⁢   ⁢ i × sin ⁢   ⁢ ( θ i ) ] EAstdev =

Abstract: In a golf ball having a plurality of dimples (12) formed in its surface, each dimple prior to paint coating consists of a major concave surface portion (20) circumscribed by a peripheral convex surface portion (22). The peripheral convex surface portion connects to the major concave surface portion at a point of inflection (30) which is located at a distance of 10-50% of the dimple depth (d) from the edge (26) of the peripheral convex surface portion.

Abstract: When the spherical surface of a golf ball is divided into a plurality of substantially congruent spherical triangles, dimples are substantially equally distributed in the spherical triangles. The spherical triangles are minimum triangular units which are substantially congruent with each other. The dimples distributed in each minimum triangular unit include crossing dimples that each lie across a side of the minimum triangular unit. The total of the crossing lengths of the crossing dimples is 70-80% of the total side length of the minimum triangular unit. The golf ball is improved in the symmetry of elevation angle and carry, and has good aerodynamic performance and an increased total flight distance.

Abstract: In a golf ball having on its surface a multiplicity of dimples, the dimples include a majority of large dimples with a diameter of 3.0 to 4.2 mm and account for at least 65% of the entire ball surface area. The large dimples have a depth of 0.1-0.35 mm, an edge angle of up to 30°, and a radius of curvature at the edge of 1-50 mm. Not only excellent flight performance is achieved, but the ball can be smoothly released from a mold at the end of molding.

Abstract: A spherical body having a core and a surface layer is manufactured by a method comprising a preforming step in which a pair of sheet blanks (1) are formed into half-shells (11) in a two-part mold (2) having hemispherical concave mold halves by pressing each blank from one side while applying vacuum suction to the other side; a surface layer forming step in which the half-shells are loaded into another two-part mold (12) having pattern-forming projections, the core (19) is placed on one mold half, and the other mold half is joined thereto to close the mold, thereby pressing the core against the inner side of each half-shell, concurrent with which vacuum suction is applied to the outer side; and a molding step in which the surface layer is fused and solidified onto the core within the closed mold.

Abstract: Using a mold comprising typically two split mold segments which are mated in a separable manner to define a spherical mold cavity therein, a golf ball having a multiplicity of dimples in its surface is molded by feeding a molding material into the mold cavity. The mold is split along a line off a horizontal great circle of the golf ball into two split mold segments having different areas of contact with the ball. The golf ball as molded is always caught and left in the larger mold segment and thus can be easily removed from the mold by a routine operation.