Washer device

Claim 1

A dual action spring washer including an annular centrally apertured washer body, said body including a first circumferentially continuous outer marginal spring section which is substantially conical in axial cross section and having a circular outer periphery, a second, inner marginal spring section which is substantially conical in axial cross section and extends axially upwardly beyond said first section, the outer periphery of said second section defining a polygon of at leas four sides and which polygonal periphery is spaced radially inwardly of the outer periphery of said first section to provide said outer marginal spring section with a varying width about its circumference, a short, rigid, strut section integrally joining said first and second sections, said strut section extending generally parallel to the washer axis, the strut section including protuberances which are U-shaped in circumferential cross section and located on each side of the polygon intermediate the corners of the polygonally shaped section, each protuberance including a top wall and a pair of side walls extending radially outwardly from the outer periphery of the inner section the outermost extremities of the side walls and top wall merging with the surface of the outer marginal spring section, the outermost extremity of the top wall and side walls providing a bearing surface for the strut section having a periphery greater than the periphery of the polygonal section, the radial distance from the axis of the apertured washer body to the outermost portion of the protuberances being less than the radial distance from the axis of the aperture to the circular periphery of the first outer marginal spring section, the outer spring section thus being provided with an uninterrupted frustoconical marginal spring-like clamping surface extending radially outwardly of the termination point of the protuberances and corners of the polygon, the marginal periphery of the first section lying on a plane which is spaced axially downwardly from the base of the side walls and U-shaped end walls of the protuberances, the inner marginal periphery defining the aperture in the second section lying in a plane which is spaced axially upwardly from the top wall of the protuberance which allows the outer peripheral surface of the outer spring section to yield axially under load, the side walls of the protuberances being extensions of the strut section and the top wall of the protuberances being narrow extensions of the inner conical section providing circumferentially spaced clamping surfaces adapted to be engaged by a clamping surface such as the clamping surface of a rotary threaded fastener and to uniformly distribute the clamping forces in the dual action spring washer system without significantly altering the spring characteristics of either the inner spring section or the Outer spring section and significantly decrease the stress concentration at the junctures of the strut with the inner and outer sections.