SCREW

Abstract: a screw includes a shank, a head and a drill portion joined to opposite ends of the shank, thread convolutions spiraled on the shank, ribs protruding from the shank, a discharging portion formed between any two adjacent ribs, and cutting portions formed on the thread convolutions. each thread convolution has two thread flanks converging at a thread crest and forms respective thread roots by which different vertical distances are defined. one of the thread flanks includes flank sections having different flank angles. therefore, the thread convolutions are asymmetric. the discharging portion has two inclined surfaces connected to the ribs and an accommodation groove formed therebetween. the cutting portions and ribs serve to cut and cooperate with the asymmetric arrangement to increase the cutting efficiency, thereby reducing screwing resistance, enhancing pull-out resistance whereby the screw is not easily pulled out of a workpiece, and removing chips quickly through the discharging portion.

Inventor(s): KOU-TSAIR SU, CHEN-LONG SU

CPC Classification: F16B25/0042 (Screws that cut thread in the body into which they are screwed, e.g. wood screws {( takes precedence; joining sheets or plates using screws with two separate threads , using screws with adjustment sleeves )})

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