Patents Assigned to Nissan Screw Co., Ltd.
  • Spring washer and method for making the same
    Patent number: 5809820
    Abstract: A spring washer improves resistance to loosening of fasteners tightened thereon. The spring washer is stronger than prior art devices. On the upper and lower surfaces of the spring washer, approximately 1/5-1/4 of the width inward from the outer perimeter is formed without V-shaped grooves. The remaining flat portions are formed with V-shaped grooves in various patterns. These V-shaped grooves increase the coefficient of friction and resist loosening of the spring washer.
    Type: Grant
    Filed: May 27, 1997
    Date of Patent: September 22, 1998
    Assignee: Nissan Screw Co., Ltd.
    Inventor: Toshiaki Morimoto