Abstract: A pair of left and right front frames are formed with brittle sections on proximal portions of the frames, by the provision of the smaller cross-sectional area than other sections of the frame. The brittle sections and their peripheral sections are processed so as to become approximately equal to the other sections of the front frames in axial compressive strength by way of a hardening treatment like quenching. In an early-phase of a collision, the hardened brittle sections will not buckle so as to induce larger initial load. Thereafter, the brittle sections will buckle because of their lower ductility, so that the front frames begin bending deformation to effectively absorb the collision energy.

Abstract: A method for producing a formed member made of a steel sheet according to the present invention is characterized by preparing a steel sheet material having tensile strength of 500 MPa or less and containing a nitriding element; forming a formed member having a predetermined shape by performing a plastic forming on the steel sheet material; and performing a nitriding treatment on the formed member so that an average hardness in the sheet thickness direction of the resultant steel sheet member is Hv 300 or more by Vickers hardness, and further characterized in that the difference in hardness between the surface part and the inside center part in the thickness direction of the steel sheet member of the formed member is Hv 200 or less by Vickers hardness, thereby it is possible to reliably obtain a formed member having a sufficiently high strength after a nitriding treatment while ensuring a plastic formability of a steel sheet in obtaining a formed member made of a steel sheet member of high strength by performi

Abstract: In a semi-molten metal injection molding method of producing a thin molded product by injecting a semi-molten metal M of a magnesium alloy, in a semi-melting state, into a cavity of a mold through a product gate, characterized in that it is made possible to obtain a high-quality thin molded product by maintaining satisfactory fluidity of the semi-molten metal M. A grain size of the solid fraction in the melt M is set to not more than 0.13 times the average thickness of the product portion of the thin molded product and a molten metal velocity at the product gate is set to not less than 30 m/s and, moreover, a solid fraction Fs (%) of the semi-molten metal M and a grain size D (&mgr;m) of the solid phase of the semi-molten metal M are set so as to define the relationship Fs×D≦1500.

Abstract: A pair of left and right front frames are formed with brittle sections on proximal portions of the frames, by the provision of the smaller cross-sectional area than other sections of the frame. The brittle sections and their peripheral sections are processed so as to become approximately equal to the other sections of the front frames in axial compressive strength by way of a hardening treatment like quenching. In an early-phase of a collision, the hardened brittle sections will not buckle so as to induce larger initial load. Thereafter, the brittle sections will buckle because of their lower ductility, so that the front frames begin bending deformation to effectively absorb the collision energy.

Abstract: In a semi-molten metal injection molding method of producing a thick molded article by injecting a semi-molten melt M of a magnesium alloy, in a semi-melting state, into a cavity 13 of a mold 11 through a product gate 17, characterized in that it is made possible to obtain a high-quality thick molded article free from internal defects. A solid fraction of the semi-molten melt M is set to not less than 10%, and more preferably within a range of 40 to 80%. A sectional area Sg of a product gate portion of the thick molded article corresponding to the product gate 17 is set to not less than 0.1 times a sectional area Sp in the vicinity of the product gate 17 in the product portion corresponding to the cavity 13. Furthermore, a product gate velocity Vg mm/s of the semi-molten melt M, a sectional area Sg mm2 of the product gate portion of the thick molded article and a volume Vp mm3 of the product portion are set so as to satisfy the following relationships: Vg≦8.0×104; and, Vg×Sg/Vp≧10.

Abstract: A method for producing a formed member made of a steel sheet according to the present invention is characterized by preparing a steel sheet material having tensile strength of 500 MPa or less and containing a nitriding element; forming a formed member having a predetermined shape by performing a plastic forming on the steel sheet material; and performing a nitriding treatment on the formed member so that an average hardness in the sheet thickness direction of the resultant steel sheet member is Hv 300 or more by Vickers hardness, and further characterized in that the difference in hardness between the surface part and the inside center part in the thickness direction of the steel sheet member of the formed member is Hv 200 or less by Vickers hardness, thereby it is possible to reliably obtain a formed member having a sufficiently high strength after a nitriding treatment while ensuring a plastic formability of a steel sheet in obtaining a formed member made of a steel sheet member of high strength by performi

Abstract: In a semi-molten metal injection molding method of producing a thin molded product by injecting a semi-molten metal M of a magnesium alloy, in a semi-melting state, into a cavity of a mold through a product gate, characterized in that it is made possible to obtain a high-quality thin molded product by maintaining satisfactory fluidity of the semi-molten metal M. A grain size of the solid fraction in the melt M is set to not more than 0.13 times the average thickness of the product portion of the thin molded product and a molten metal velocity at the product gate is set to not less than 30 m/s and, moreover, a solid fraction Fs (%) of the semi-molten metal M and a grain size D (&mgr;m) of the solid phase of the semi-molten metal M are set so as to define the relationship Fs×D≦1500.

Abstract: In a semi-molten metal injection molding method of producing a thick molded article by injecting a semi-molten melt M of a magnesium alloy, in a semi-melting state, into a cavity 13 of a mold 11 through a product gate 17, characterized in that it is made possible to obtain a high-quality thick molded article free from internal defects. A solid fraction of the semi-molten melt M is set to not less than 10%, and more preferably within a range of 40 to 80%. A sectional area Sg of a product gate portion of the thick molded article corresponding to the product gate 17 is set to not less than 0.1 times a sectional area Sp in the vicinity of the product gate 17 in the product portion corresponding to the cavity 13. Furthermore, a product gate velocity Vg mm/s of the semi-molten melt M, a sectional area Sg mm2 of the product gate portion of the thick molded article and a volume Vp mm3 of the product portion are set so as to satisfy the following relationships: Vg ≦8.0×104; and, Vg×Sg/Vp≧10.

Abstract: In order to provide a die structure for injection molding of a light alloy free from gas defects, and a method of molding a light alloy parts using the die, the die structure is used for converting a light alloy into a semi-molten state, wherein a solid phase and a liquid phase coexist, or a molten state at a temperature just above a melting point and injecting the molten metal into an interior cavity portion, and S1/S2 of a gate sectional area S1 with respect to a maximum sectional area S2 of the cavity of the mold which area is almost perpendicular to the flowing direction of the melt therein is set in a range of 0.06 to 0.5.

Abstract: A light metal alloy material has excellent plastic workability. The method of producing the light metal alloy material comprises a light metal as a matrix, which is injection-molded at a solid phase proportion of not more than 20%. The injection molded material has a limiting upsetting rate of not more than 70% and excellent moldability. This injection molded material can be molded into a final molded article by means of single-step forging.

Abstract: In a semi-molten metal injection molding method of producing a thick molded article by injecting a semi-molten melt M of a magnesium alloy, in a semi-melting state, into a cavity 13 of a mold 11 through a product gate 17, characterized in that it is made possible to obtain a high-quality thick molded article free from internal defects. A solid fraction of the semi-molten melt M is set to not less than 10%, and more preferably within a range of 40 to 80%. A sectional area Sg of a product gate portion of the thick molded article corresponding to the product gate 17 is set to not less than 0.1 times a sectional area Sp in the vicinity of the product gate 17 in the product portion corresponding to the cavity 13. Furthermore, a product gate velocity Vg mm/s of the semi-molten melt M, a sectional area Sg mm2 of the product gate portion of the thick molded article and a volume Vp mm3 of the product portion are set so as to satisfy the following relationships: Vg≦8.0×104; and, Vg×Sg/Vp≧10.

Abstract: Material characteristics that a foamed filler material (s) to be filled in a frame cross section (fr) should have are discussed. By using a material complying with the characteristics, the energy absorbability of the frame (fr) is effectively enhanced. In a frame structure (fr) for vehicle bodies in which a filler material is filled in at least part of the cross section of a frame, the filler material is set to a mean compressive strength of not less than 4 MPa and/or a maximum bending strength of not less than 10 MPa. More particularly, the filler material is set to a mean compressive strength of not less than 5 MPa and/or a maximum bending strength of 60 MPa.

Abstract: In order to provide a die structure for injection molding of a light alloy free from gas defects, and a method of molding a light alloy parts using the die, the die structure is used for converting a light alloy into a semi-molten state, wherein a solid phase and a liquid phase coexist, or a molten state at a temperature just above a melting point and injecting the molten metal into an interior cavity portion, and S1/S2 of a gate sectional area S1 with respect to a maximum sectional area S2 of the cavity of the mold which area is almost perpendicular to the flowing direction of the melt therein is set in a range of 0.06 to 0.5.

Abstract: The invention provides a method for injection molding a semi-molten melt of metal to a product, wherein a semi-molten melt of metal is injected into a cavity of the mold through a nozzle of injector to mold the product which is divided in a lower solid fraction portion to require strength and a higher solid fraction portion to require molding accuracy along flow of the melt inside the cavity. In the method of the invention, a part of the melt to be earlier injected is determined to be at a lower temperature in the injector than a part to be later injected among the melt parts composing said lower and higher solid portions in the cavity by injecting a batch of the melt, and that the melt is injected into the cavity on the side on which said lower solid fraction portion for the strength of the product is formed.

Abstract: The tooth portion of a metal ring gear is subjected to shot peening after the ring gear is mechanically connected to a metal boss portion by plastic deformation of the metal material.

Abstract: Disclosed herein in dies for forging a gear-shaped part made of a sheet metal, comprising a cylindrical die for forming, in cooperation with a cylindrical punch, tooth portions and bottom land portions at a peripheral wall portion of a cup-shaped work integrally formed from the sheet metal, wherein ridges and grooves provided at the inner peripheral surface of the cylindrical die in the axial direction of the die in order to form the tooth portions and the bottom land portions are such that, in the direction from an insertion-side opening of the cylindrical die toward the depth of the die, the height of the ridges is gradually increased to a final height, then the width of the ridges is gradually increased to a final width, and thereafter the depth of the grooves is gradually decreased to a final depth.