COUNTERSUNK SCREW Russian patent published in 2008 - IPC F16B35/06 F16B23/00 F16B25/00 

FIELD: mechanical engineering; fasteners.

SUBSTANCE: proposed countersunk screw has threaded body and countersunk head with conical surface tapering towards threaded body with countersink angle α. Conical surface has several ribs spaced over perimeter and defining conical enveloping surface with taper angle β. Countersink angle α of conical surface is less than rib taper angle β. Ribs have outer contact surfaces defining conical enveloping surface. When screw is used for fastening cover plates or other like parts by turning into countersunk hole, surface clamping appears between ribs and corresponding counter sunk holes which prevents damage to surface. Ribs feature cutting effect to form countersinking in soft material when screw is directly screwed into soft material, such as wood. Proposed screw is good for turning into hard material, such as metal, and soft material, such as wood.

EFFECT: improved service properties.

14 cl, 4 dwg