Patents Assigned to Chuo Hatsujo Kabshiki Kaisha
  • Coil spring resistive to delayed fracture and manufacturing method of the same
    Patent number: 6017641
    Abstract: A coil spring made of an oil-tempered steel wire with internal hardness of more than Hv 550 in cross-section, the surface hardness of the oil-tempered steel wire being determined in an extent between Hv 420 in a minimum value and hardness defined by subtraction of Hv 50 from the internal hardness in a maximum value.
    Type: Grant
    Filed: March 12, 1998
    Date of Patent: January 25, 2000
    Assignees: Chuo Hatsujo Kabshiki Kaisha, Honda Giken Kogyo Kabushiki Kaisha
    Inventors: Toshinori Aoki, Taisuke Nishimura, Takashi Otowa