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Kyoto, Japan

Patent
Honda Corporation and Nichidai Corporation | Date: 2010-03-25

The present invention provides a production apparatus for crankshaft, including: a die which has a lower die, an upper die, and plural side forming punches, the upper die being provided movably to the lower die, the side forming punches moving perpendicularly to a movement direction of the upper die; a press ram which moves the upper die to the lower die, closes a material of the crankshaft, and forms the material; cam mechanisms which are provided for the side forming punches and which move the side forming punches to an inside portion of the die in accordance with movement of the press ram; a grade separation structure which is provided to at least one of the side forming punches in order to prevent interference of the side forming punches with each other.


Ebara R.,Hiroshima Institute of Technology | Nohara R.,Hiroshima Institute of Technology | Ueji R.,Kagawa University | Ogura A.,Nichidai Corporation | And 2 more authors.
Key Engineering Materials | Year: 2010

High cycle fatigue behavior of the representative cold forging die steel, YXR3 with Rockwell C scale hardness number of 60.0 is investigated. Axial fatigue strength of plane and notched bar specimens with stress concentration factor, Kt of 1.5, 2.0 and 2.5 is presented. The emphasis is placed upon the subsurface crack initiation observed on notched specimens failed at number of cycles over than 106 cycles. Crack initiation and propagation mode of cold forging die steel is discussed with respect to fracture surface morphology. © (2010) Trans Tech Publications, Switzerland. Source


Ebara R.,Hiroshima Institute of Technology | Nakamura K.,Hiroshima Institute of Technology | Ogura A.,Nichidai Corporation | Ishihara Y.,Nichidai Corporation | Hamaya S.,Nichidai Corporation
18th European Conference on Fracture: Fracture of Materials and Structures from Micro to Macro Scale | Year: 2010

Fatigue strength of as-lapped notched HAP72 specimen heat treated in vacuum at 109 cycles was 550MPa and 50MPa higher than that of as-machined specimen. Effect of notch on gigacycle fatigue strength of HAP72 was prominent, while heat treatment effect was not observed. Fatigue crack initiated at the notched surface of all notched specimens. On the contrary fatigue crack initiated at nonmetallic inclusion located at subsurface for plane specimen. Fatigue crack initiation behavior of HAP72 is discussed with respect to different fracture surface morphology in plane and notched specimen. Source


Ebara R.,Hiroshima Institute of Technology | Nakamoto K.,Hiroshima Institute of Technology | Ogura A.,Nichidai Corporation | Ishihara Y.,Nichidai Corporation | Hamaya S.,Nichidai Corporation
Key Engineering Materials | Year: 2011

Giga-cycle fatigue behavior of notched specimens with stress concentration factor, Kt of 1.5, 2.0 and 2.5 for 0.65 mass% carbon matrix high speed steel, YXR3 with Rockwell C scale hardness number of 60.7 is investigated. The higher the stress concentration factor the lower the giga-cycle fatigue strength is. The emphasis is placed upon the subsurface crack initiation observed on all notched specimens. Crack initiation mode of high speed steel is discussed with respect to fracture surface morphology. Source


Ebara R.,Hiroshima Institute of Technology | Takeda K.,Hiroshima Institute of Technology | Iwamoto M.,Hiroshima Institute of Technology | Fujimoto H.,Hiroshima Institute of Technology | And 2 more authors.
Zairyo/Journal of the Society of Materials Science, Japan | Year: 2011

Microfractographic features in fracture surfaces for tensile, fatigue, impact, three point bending specimens of cold forging die steels with Rockwell C scale hardness number of 52 to 68 are presented. The emphasis is placed upon the stretched zone formation ahead of the fatigue crack and the relation between the stretched zone width and fracture toughness. Fatigue crack initiation behavior of plane and notched specimens are also characterized in low cycle up to giga-cycle ranges. A couple of microfractographic analyzed results for failed actual cold forging dies are exemplified. It can be concluded that qualitative and quantitative analysis by use of microfractograpy are possible for cold forging die failures. © 2011 The Society of Materials Science, Japan. Source

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