A method for forming a hitch ball head includes a pre-forging step, in which a columnar blank is prepared and is extruded to form a pre-forged blank; a first forging step, in which the pre-forged blank is extruded and drawn to form first and second forged portions; a second forging step, in which the pre-forged blank is extruded and drawn to shorten a length of the first forged portion and to form the second forged portion into a to-be-formed section and a columnar base section; a first forming step, in which the pre-forged blank is extruded to form the first forged portion into a ball head portion and to form the columnar base section into a connecting segment and a columnar segment; and a second forming step, in which the pre-forged blank is extruded to form the to-be-formed section into a seat section to thereby obtain the hitch ball head.

A springback amount evaluation method evaluates an amount of springback after die release of a press forming product by a computer and includes: setting a plurality of section planes intersecting a shape of the press forming product at predetermined intervals; obtaining a sectional shape of the press forming product for each of the set section planes; and obtaining an orientation of each of the sectional shapes in each section plane as a direction of the each of the sectional shapes, wherein for each of a shape to be a reference of the press forming product and a shape after the die release, the above-described three steps are performed, and the amount of springback is evaluated by comparing, for all of the section planes, the obtained directions of the sectional shapes for the shape to be the reference and for the shape after the die release.

A springback amount evaluation method evaluates an amount of springback after die release of a press forming product by a computer and includes: setting a plurality of section planes intersecting a shape of the press forming product at predetermined intervals; obtaining a sectional shape of the press forming product for each of the set section planes; and obtaining an orientation of each of the sectional shapes in each section plane as a direction of the each of the sectional shapes, wherein for each of a shape to be a reference of the press forming product and a shape after the die release, the above-described three steps are performed, and the amount of springback is evaluated by comparing, for all of the section planes, the obtained directions of the sectional shapes for the shape to be the reference and for the shape after the die release.

The present invention provides a method of near-net-shape forged molding of the coupler knuckle of the railway vehicle. The present invention solves the problems that the manufacturing the forged coupler knuckle is difficult, and the process is complex, etc. The method of the present invention includes the following steps: material preparation, heating, blank prefabrication, pre-forging, closed-die forging, quenched-tempered heat treatment using waste heat, finish machining, flaw detection, etc. With the closed-die forging technology, the near-net-shape molding of the coupler knuckle can be achieved. The energy and the material are saved. The contour shape and the size do not need to be machined. The use ratio of the material can reach more than 92%. Moreover, during the entire molding, the workpiece is in the three-dimensionally stressed state all the time. The product has a dense texture, a high toughness, a good fatigue resistance, and a long lifetime.

The present invention provides a method of near-net-shape forged molding of the coupler knuckle of the railway vehicle. The present invention solves the problems that the manufacturing the forged coupler knuckle is difficult, and the process is complex, etc. The method of the present invention includes the following steps: material preparation, heating, blank prefabrication, pre-forging, closed-die forging, quenched-tempered heat treatment using waste heat, finish machining, flaw detection, etc. With the closed-die forging technology, the near-net-shape molding of the coupler knuckle can be achieved. The energy and the material are saved. The contour shape and the size do not need to be machined. The use ratio of the material can reach more than 92%. Moreover, during the entire molding, the workpiece is in the three-dimensionally stressed state all the time. The product has a dense texture, a high toughness, a good fatigue resistance, and a long lifetime.

A method for forming a hitch ball head includes a pre-forging step, in which a columnar blank is prepared and is extruded to form a pre-forged blank; a first forging step, in which the pre-forged blank is extruded and drawn to form first and second forged portions; a second forging step, in which the pre-forged blank is extruded and drawn to shorten a length of the first forged portion and to form the second forged portion into a to-be-formed section and a columnar base section; a first forming step, in which the pre-forged blank is extruded to form the first forged portion into a ball head portion and to form the columnar base section into a connecting segment and a columnar segment; and a second forming step, in which the pre-forged blank is extruded to form the to-be-formed section into a seat section to thereby obtain the hitch ball head.

A method for forming a hitch ball head includes a pre-forging step, in which a columnar blank is prepared and is extruded to form a pre-forged blank; a first forging step, in which the pre-forged blank is extruded and drawn to form first and second forged portions; a second forging step, in which the pre-forged blank is extruded and drawn to shorten a length of the first forged portion and to form the second forged portion into a to-be-formed section and a columnar base section; a first forming step, in which the pre-forged blank is extruded to form the first forged portion into a ball head portion and to form the columnar base section into a connecting segment and a columnar segment; and a second forming step, in which the pre-forged blank is extruded to form the to-be-formed section into a seat section to thereby obtain the hitch ball head.

A springback-reduced part formed by performing a springback reduction on a press-formed part that is formed by a press forming of a blank sheet made of a metal sheet. The springback-reduced part is formed by setting each element of an analytic model of the press-formed part to a stressed state that causes a springback, performing an optimization analysis for shape to detect a portion of the press-formed part that highly contributes to the rigidity thereof, applying a rigidity improving means on a specific portion of the press-formed part on the basis of the detected portion, and performing the press forming.

A springback-reduced part formed by performing a springback reduction on a press-formed part that is formed by a press forming of a blank sheet made of a metal sheet. The springback-reduced part is formed by setting each element of an analytic model of the press-formed part to a stressed state that causes a springback, performing an optimization analysis for shape to detect a portion of the press-formed part that highly contributes to the rigidity thereof, applying a rigidity improving means on a specific portion of the press-formed part on the basis of the detected portion, and performing the press forming.

A pillar for a motor vehicle bodywork is disclosed having a main element with an upper coupling section for attaching to a roof frame, and a secondary element composed of metallic alloy. The secondary element is connected in a planar fashion at least over certain sections of the main element, and the main element has a middle layer composed of a hardened steel alloy, and at least one outer layer which bounds the middle layer toward the outside.