SPIRAL DRIVE FASTENING ELEMENT WITH FRICTION ENGAGED SURFACES Russian patent published in 2009 - IPC F16B23/00 F16B35/06 B21K1/46 B23G9/00 

FIELD: machine building.

SUBSTANCE: invention is related to fastening elements. Fastening element has indent. Indent has central section and multiple tabs that diverge radially outside from central section. Every tab has adjusting wall and wall for withdrawal, at that tabs have such configuration that at least one of adjusting wall and wall for withdrawal creates spiral segment. Specified indent additionally contains transfer surface, which connects specified adjusting wall and wall for withdrawal of adjusting tabs, surface of interference arranged as section of specified transfer surface, at that specified surface is located at the first radial distance from longitudinal axis in its upper section and at the second radial distance from specified longitudinal axis in its lower section, at that specified first radial distance is more than the second specified radial distance. Method for manufacture of fastening element consists of the following stages. Cylindrical steel ingot is formed, axial opening is drilled, wire is pulled through mentioned hole to provide for operation of electric corrosion treatment. Then specified indent is exposed to machine treatment, using specified operation of electric corrosion treatment to shape mold cavity. During specified operation of machine treatment transfer surface is made. Then level is determined in specified indent, where specified interference fit is carried out, specified depth of mentioned indent is measured from specified level, where specified interference fit is carried out. Afterwards upper part of specified ingot is exposed to machine treatment to specified set depth.

EFFECT: provision of interference fit between screw driver and fastening element.

13 cl, 11 dwg