Graduated-Load Spring Washer System for Screws and Threaded Fasteners.
Patent, Filed 17 Aug 88, patented 25 Sep 90,
DEPARTMENT OF THE NAVY WASHINGTON DC
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A graduated-load spring washer system for screws and threaded fasteners uses a deflection coils spring of slightly less than one coil with special end configurations for anti-marring. A cross-section of the coil spring is substantially trapezoidal, with the outer periphery thickness being the dimension of the trapezoid base and target than the inner thickness dimension. When placed under the head of a threaded fastener and flattened upon tightening of the fastener, the device maintains a large tailored preload to prevent loosening even during and after stress relaxation and creep, and eliminates the need for a usual flat washer below the coil to prevent marring. The device also eliminates requirements for use of torque application measuring tools because perload can be determined by sight or tactile sensing. Patents. JHD
- Couplers, Fasteners and Joints