Provided are a method of for machining the outer circumference of a metal end cross-section, the method being capable of easily forming at least any of a deep groove, a deep recess, and a flange which are smooth and uniform in the longitudinal direction of a metal rod or metal pipe in the periphery of the cross-section of any of the end part of the metal rod or metal pipe, the drawn end part of the metal rod or metal pipe, and the hub hole forming part of the metal pipe; and a method for joining a metal component obtained by the machining method with another member. The machining method of the present invention is characterized in that: splitting is advanced by successively repeating press forming operation multiple times by using a slitting punch, in which a tip part has a sharp cutting edge, and the cutting edge is formed so as to have a shape equal to or partly equal to the outer shape of the cross section of a metal end part and so as to have a diameter smaller than the outer diameter of the cross section of the splitting object; and in order to control the depth of metal cracking cleft created with each press forming operation, a pressing die for pinching the outside of a metal rod or at least a pressing die of one side of pressing dies for pinching the inside and the outside of a metal pipe is disposed while its position is moved according to the distance of a split portion.

Equipment including a rigid plate provided with a plurality of cutters configured to be impressed in sequence against a swaged annular collar of an inner ring of a wheel hub, the collar being formed with a first radial profile; the cutters sliding axially through the plate and towards a first face of the plate resting in abutment against the collar; wherein the first face of the plate is provided in the region of the cutters with a concave annular seat having a second radial profile configured to copy at least partly the first radial profile of the collar, the annular seat being configured to be passed through by the cutters during the step for impression against the collar and to contain any radial flow of the metallic material which forms the collar.

Equipment including a rigid plate provided with a plurality of cutters configured to be impressed in sequence against a swaged annular collar of an inner ring of a wheel hub, the collar being formed with a first radial profile; the cutters sliding axially through the plate and towards a first face of the plate resting in abutment against the collar; wherein the first face of the plate is provided in the region of the cutters with a concave annular seat having a second radial profile configured to copy at least partly the first radial profile of the collar, the annular seat being configured to be passed through by the cutters during the step for impression against the collar and to contain any radial flow of the metallic material which forms the collar.

A process for preparing a multi-thickness welded steel vehicle rail, the process comprises the steps of: (a) forming a first tube having a first outer diameter, an inner diameter and a first wall thickness; (b) forming a second tube having the first outer diameter, a second inner diameter and a second wall thickness different than the first wall thickness; (c) swaging a first end of the first tube to a second outer diameter less than the second inner diameter of the second tube; (d) inserting the swaged first end of the first tube into an end of the second tube to form a joint; (e) welding the first tube and the second tube together to form a weld at the joint to form a tube blank with a heat affected zone of lower metal strength in the area of the weld; (f) preheating the tube blank to create a common crystalline microstructure along a length of the tube blank; (g) introducing the tube blank into a blow molding tool having inner molding walls; (h) molding the tube blank at an elevated temperature by expanding the tube blank against the inner molding walls of the molding tool by injecting a pressurized medium into an interior cavity of the tube blank; and (i) quenching the tube blank by replacing the pressurized medium with a cooling medium through the molding tool and the tube blank to achieve a rapid cooling effect on the tube blank and to create a completed vehicle rail with essentially uniform material strength across the weld. A completed vehicle rail has an overlapped welded structure and uniform microcrystalline structure along the length of the rail.

A process for preparing a multi-thickness welded steel vehicle rail, the process comprises the steps of: (a) forming a first tube having a first outer diameter, an inner diameter and a first wall thickness; (b) forming a second tube having the first outer diameter, a second inner diameter and a second wall thickness different than the first wall thickness; (c) swaging a first end of the first tube to a second outer diameter less than the second inner diameter of the second tube; (d) inserting the swaged first end of the first tube into an end of the second tube to form a joint; (e) welding the first tube and the second tube together to form a weld at the joint to form a tube blank with a heat affected zone of lower metal strength in the area of the weld; (f) preheating the tube blank to create a common crystalline microstructure along a length of the tube blank; (g) introducing the tube blank into a blow molding tool having inner molding walls; (h) molding the tube blank at an elevated temperature by expanding the tube blank against the inner molding walls of the molding tool by injecting a pressurized medium into an interior cavity of the tube blank; and (i) quenching the tube blank by replacing the pressurized medium with a cooling medium through the molding tool and the tube blank to achieve a rapid cooling effect on the tube blank and to create a completed vehicle rail with essentially uniform material strength across the weld. A completed vehicle rail has an overlapped welded structure and uniform microcrystalline structure along the length of the rail.

A method of manufacturing a rectangular tube having a stepped portion includes: forming V-shaped grooves on a rectangular tube at surfaces of an end thereof in a direction parallel to a longitudinal direction thereof; and pressing each of the surfaces having the V-shaped grooves formed thereon with a rotating roll from outside to inside, whereby the end of the rectangular tube is radially reduced.

A method of manufacturing a rectangular tube having a stepped portion includes: forming V-shaped grooves on a rectangular tube at surfaces of an end thereof in a direction parallel to a longitudinal direction thereof; and pressing each of the surfaces having the V-shaped grooves formed thereon with a rotating roll from outside to inside, whereby the end of the rectangular tube is radially reduced.

A ball screw is provided in which an outer circumferential formation is formed at a portion facing a ball circulating passage out of outer circumferential surface of a nut. The ball screw includes: a screw shaft having on its outer circumferential surface a screw groove; a nut having on its inner circumferential surface a screw groove facing the screw groove; a plurality of balls rollably loaded in a spiral ball rolling passage formed by both screw grooves; and a ball circulating passage to return the balls from a start point to an end point of the ball rolling passage for recirculation. The ball circulating passage is a concaved groove formed by concaving a groove on a part of the cylindrical inner circumferential surface of the nut by plastic working. Then, a flange is integrally provided at a portion facing the ball circulating passage and the screw groove.

A ball screw is provided in which an outer circumferential formation is formed at a portion facing a ball circulating passage out of outer circumferential surface of a nut. The ball screw includes: a screw shaft having on its outer circumferential surface a screw groove; a nut having on its inner circumferential surface a screw groove facing the screw groove; a plurality of balls rollably loaded in a spiral ball rolling passage formed by both screw grooves; and a ball circulating passage to return the balls from a start point to an end point of the ball rolling passage for recirculation. The ball circulating passage is a concaved groove formed by concaving a groove on a part of the cylindrical inner circumferential surface of the nut by plastic working. Then, a flange is integrally provided at a portion facing the ball circulating passage and the screw groove.

Equipment including a rigid plate provided with a plurality of cutters configured to be impressed in sequence against a swaged annular collar of an inner ring of a wheel hub, the collar being formed with a first radial profile; the cutters sliding axially through the plate and towards a first face of the plate resting in abutment against the collar; wherein the first face of the plate is provided in the region of the cutters with a concave annular seat having a second radial profile configured to copy at least partly the first radial profile of the collar, the annular seat being configured to be passed through by the cutters during the step for impression against the collar and to contain any radial flow of the metallic material which forms the collar.