Abstract: A rack bar includes a shaft portion and a rack toothed portion provided on the shaft portion. The rack toothed portion includes a plurality of rack teeth provided side by side in an axial direction of the shaft portion to mesh with a pinion gear. Each of the rack teeth includes a tooth tip portion, a contact face arranged obliquely relative to the axial direction and configured to contact the pinion gear, and a rounded corner portion between the tooth tip portion and the contact face. A first radius defining a central area of the rounded corner portion with respect to a tooth width direction is larger than a second radius defining another area of the rounded corner portion other than the central area.

Abstract: A hollow rack bar and a method of manufacturing the hollow rack bar are provided. The hollow rack bar includes a hollow blank pipe portion having a uniform wall thickness, and a rack toothed portion. The rack toothed portion includes teeth, a flat portion having a flat surface and arranged side by side with the teeth in a direction along a center axis of the blank pipe portion, and a slanted portion provided at an end of the flat portion with respect to a direction perpendicular to the center axis and arranged to be lower than the flat portion. A length of the slanted portion projected on a straight line perpendicular to the center axis and parallel to the surface of the flat portion is longer than zero and equal to or shorter than the wall thickness of the blank pipe portion.

Abstract: The present invention includes a bar having a maximum cross section region smaller than a minimum cross section region of a hollow portion of a pipe P, and projected portions mounted along an axial direction of the bar and including a projected portion with maximum extent Hb, extent Ha of the projected portion positioned at a leading end side of the bar is set to be smaller than extent Hb of the projected portion positioned at a center side in the axial direction, and extent Hc of the projected portion positioned at a base end side of the bar is set to be less than or equal to extent Hb of the projected portion.

Abstract: A rack bar includes a shaft portion and a rack toothed portion provided on the shaft portion. The rack toothed portion includes a plurality of rack teeth provided side by side in an axial direction of the shaft portion to mesh with a pinion gear. Each of the rack teeth includes a tooth tip portion, a contact face arranged obliquely relative to the axial direction and configured to contact the pinion gear, and a rounded corner portion between the tooth tip portion and the contact face. A first radius defining a central area of the rounded corner portion with respect to a tooth width direction is larger than a second radius defining another area of the rounded corner portion other than the central area.

Abstract: With a first push rod which is to be inserted/removed into/from a steel pipe through an opening at one end and a second push rod which is to be inserted/removed into/from the steel pipe through an opening at the other end, a metal core disposed on a side on which the first push rod is inserted/removed into/from the die assembly is sandwiched and this metal core is stopped from rotating with the first push rod. With the state of stopping the rotation of the first push rod, the metal core is introduced into the steel pipe through the opening at the one end by both the push rods. After the metal core is pressed into the steel pipe while stopped from rotating with the first push rod, this metal core is pushed back by the second push rod.

Abstract: A rack bar includes a shaft: portion, a rack toothed portion provided on the shaft portion, and a dummy toothed portion. The rack toothed portion includes a plurality of rack teeth provided side by side in an axial direction of the shaft portion, each of the rack teeth including a contact face arranged obliquely relative to the axial direction to contact the pinion gear. The dummy toothed portion includes at least one dummy tooth provided on at least one side of the rack toothed portion in the axial direction such that the dummy tooth is arranged parallel to and next to the rack. teeth. The dummy tooth is designed such that a whole height of the dummy tooth is smaller than a whole height of each of the rack teeth.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The present invention includes a bar having a maximum cross section region smaller than a minimum cross section region of a hollow portion of a pipe P, and projected portions mounted along an axial direction of the bar and including a projected portion with maximum extent Hb, extent Ha of the projected portion positioned at a leading end side of the bar is set to be smaller than extent Hb of the projected portion positioned at a center side in the axial direction, and extent Hc of the projected portion positioned at a base end side of the bar is set to be less than or equal to extent Hb of the projected portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: With a first push rod which is to be inserted/removed into/from a steel pipe through an opening at one end and a second push rod which is to be inserted/removed into/from the steel pipe through an opening at the other end, a metal core disposed on a side on which the first push rod is inserted/removed into/from the die assembly is sandwiched and this metal core is stopped from rotating with the first push rod. With the state of stopping the rotation of the first push rod, the metal core is introduced into the steel pipe through the opening at the one end by both the push rods. After the metal core is pressed into the steel pipe while stopped from rotating with the first push rod, this metal core is pushed back by the second push rod.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The present invention includes a bar having a maximum cross section region smaller than a minimum cross section region of a hollow portion of a pipe P, and projected portions mounted along an axial direction of the bar and including a projected portion with maximum extent Hb, extent Ha of the projected portion positioned at a leading end side of the bar is set to be smaller than extent Hb of the projected portion positioned at a center side in the axial direction, and extent Hc of the projected portion positioned at a base end side of the bar is set to be less than or equal to extent Hb of the projected portion.

Abstract: A rack bar of a power steering unit for a vehicle has improved bending strength. The rack bar includes a rod portion which fits slidably into an oil seal attached to a cylinder portion of a power cylinder, and a rack portion which is formed with the rod portion through a connecting portion and which meshes with a pinion. Quenching is applied the rod portion and to the rack portion, preferably under different conditions. The quenching applied to the rack portion also is applied to at least a portion of the connecting portion.

Abstract: A manufacturing method of a hollow rack bar wherein the load imposed on the rack teeth configuration of a forming die is reduced and precision level of the formation of rack teeth is improved. After the formation of a flat portion, a steel pipe is placed in the forming die having a rack-teeth configuration and a plurality of mandrels having extruding portions of different sizes are sequentially inserted into the steel pipe in order to form rack teeth. A mandrel having a planar extruding portion is firstly inserted and then a mandrel having an extruding portion with an approximately central depression in the longitudinal direction is inserted. The width of the mandrels is smaller than the inside diameter of the steel pipe.

Abstract: A method for producing a polyolefin is disclosed which comprises polymerizing an .alpha.-olefin in the presence of a catalyst composition comprising (A) a solid catalyst component prepared by contacting (a) a solid component comprising a magnesium alkoxide and/or a magnesium salt of a fatty acid supported on an inorganic oxide composed of at least one member selected from the group consisting of oxides of elements belonging to Groups II, III and IV of the periodic table and/or a composite inorganic oxide containing at least one member selected from the group consisting of oxides of elements belonging to Groups II, III and IV of the periodic table, the inorganic oxide or composite inorganic oxide having a surface hydroxide concentration of 3 .mu.mol/m.sup.2 or less, (b) an electron donating compound and (c) a titanium halide, (B) an organic metal compound, and (C) an electron donating compound.

Abstract: A process for producing a butene-1 polymer is disclosed which is characterized in that, in a process for producing a homopolymer of butene-1 or a copolymer of butene-1 and .alpha.-olefin other than the butene-1 in the presence a catalyst obtained from a solid catalyst component (A), an organic aluminium compound (B) and an electron donating compound (C) and under the condition of vapor phase polymerization, the solid catalyst component (A) is a non-layer solid catalyst component obtained by producing a carrier by chlorinating at least one kind of organic magnesium compounds represented by formulaMgR'R" (1)wherein R' and R", which may be the same or different, each represents an alkyl group having 1 to 20 carbon atoms, with at least one kind of chlorinating agents, the carrier produced is contacted in the presence of the electron donor with a titanic halide at a temperature of -25.degree. to +180.degree. C.

Abstract: This invention relates to a butene-1 copolymer composition suitable as a wire coating material which is superior in flame retardance and even if it burns, no toxic gas is generated and superior in mechanical strengths, chacterized by comprising 20-55% by weight of a butene-1 copolymer containing 80-99 mol % of butene-1 unit and 1-20% of .alpha.-olefin unit having at least 5 carbon atoms and having an intrinsic viscosity [.eta.] of 1.0-7.0 dl/g measured in decalin at 135.degree. C. and a maximum melting point of 80.degree.-120.degree. C. measured by differential scanning calorimetric analysis and 80-45% by weight of an inorganic metal hydroxide and/or an inorganic metal hydrate which have an average particle size of 0.05-6 m.