Bimate screw
AssigneeTaiwan Shan Yin Int'l Co., Ltd.
InventorGuo-Cai Su
Life of this patent
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Abstract
The present invention pertains to a bimate screw providing with a first section alternating with a second threaded section; wherein, the second threaded section has a smaller outer diameter than the first threaded section, and further a plurality of concavities are disposed on each thread of the second threaded section for defining two flanks therein. In this manner, both the first and the second threaded sections facilitate to sever and shatter cuttings so as to reduce the screwing resistance and prevent the object from being damaged under the accumulation of cuttings; simultaneously, the bimate screw effectively attains to a good resistance of extraction from the object by the concavities receiving the remaining cuttings which are not guided out of the object.
Claims6
A bimate screw comprising:
- a shank;
- a head disposed on one side of said shank;
- a distal end on the other side of said shank opposite to said head;
- a first threaded section defined by a first thread spirally disposed on said shank from said distal end toward said head;
- and
- a second threaded section defined by a second thread spiraling around said shank from said distal end toward said head and ascending thereon, said second thread being located between adjacent turns of said first thread and spaced therefrom to expose portions of said shank between said first and second threads, an outer diameter of said second thread being smaller than an outer diameter of said first thread, said second thread being formed by a plurality of pyramidally shaped teeth spaced one from another by a corresponding one of a plurality of concavities radially disposed around a circumference
- of said shank, wherein said first thread cuts and severs fibers of a workpiece into debris and said teeth of said second thread breakup the debris into chips, a portion of the chips being accumulated in said concavities and in spaces between said first and second threads for increasing a resistance to extraction of said bimate screw from the workpiece.
Dependencies are inferred from the claim text.