Screw

Abstract

A screw includes a positioning member defined on inclined cutting planes of a drilling portion of the screw for allowing a cutting edge constructed at a convergence of the cutting planes to cut stably and efficiently. A main threaded section formed on a shank of the screw is extended to connect with one end of the cutting edge. The positioning member helps the screw fixedly stand on an object. The cutting edge and the cutting planes allow cutting debris to be swiftly and smoothly extruded therefrom into the main threaded section for avoiding the accumulation of considerable cutting debris. Thereby, the screwing resistance is reduced and the drilling speed is promoted. Preferably, the fastened screw is firmly sunk in the object, and the fastening operation is completed successfully.

I claim: 
     
         1 . A screw comprising a shank portion, a head portion disposed at one end of said shank portion, a drilling portion disposed at the other end of said shank portion, and a main threaded section with a plurality of threaded units spirally disposed around said shank portion;
 wherein said drilling portion has two inclined cutting planes which are connected at a cutting edge, said cutting edge extendedly defining two ends, a positioning member being defined on said cutting planes of said drilling portion for dividing said cutting edge and stabilizing said cutting edge to execute cutting; said main threaded section extending toward said cutting edge and connecting to one end of said cutting edge for communicating said main threaded section with said drilling portion.   
     
     
         2 . The screw as claimed in  claim 1 , wherein, a threaded section including a plurality of auxiliary threaded units is disposed around said shank portion and disposed between said threaded units of said main threaded section, and a first diameter of said auxiliary threaded units is smaller than a second diameter of said threaded units of said main threaded section. 
     
     
         3 . The screw as claimed in  claim 2 , wherein, a plurality of indented units are defined on said auxiliary threaded units, and a plurality of slots are defined on part of said threaded units of said main threaded section. 
     
     
         4 . The screw as claimed in  claim 1 , wherein said positioning member is integrally protruded outwards from said cutting planes to form a pointed unit. 
     
     
         5 . The screw as claimed in  claim 2 , wherein said positioning member is integrally protruded outwards from said cutting planes to form a pointed unit. 
     
     
         6 . The screw as claimed in  claim 3 , wherein said positioning member is integrally protruded outwards from said cutting planes to form a pointed unit. 
     
     
         7 . The screw as claimed in  claim 4 , wherein, said pointed unit is formed by a plurality of inclined walls to structure a pyramid. 
     
     
         8 . The screw as claimed in  claim 5 , wherein, said pointed unit is formed by a plurality of inclined walls to structure a pyramid. 
     
     
         9 . The screw as claimed in  claim 6 , wherein, said pointed unit is formed by a plurality of inclined walls to structure a pyramid. 
     
     
         10 . The screw as claimed in  claim 4 , wherein, said pointed unit is structured into a cone. 
     
     
         11 . The screw as claimed in  claim 5 , wherein, said pointed unit is structured into a cone. 
     
     
         12 . The screw as claimed in  claim 6 , wherein, said pointed unit is structured into a cone. 
     
     
         13 . The screw as claimed in  claim 1 , wherein, said positioning member is formed by a plurality of inclined walls that are recessed inwards from said cutting planes for forming a valley on said cutting planes, and each of said inclined walls and said cutting edge are converged at a point. 
     
     
         14 . The screw as claimed in  claim 2 , wherein, said positioning member is formed by a plurality of inclined walls that are recessed inwards from said cutting planes for forming a valley on said cutting planes, and each of said inclined walls and said cutting edge are converged at a point. 
     
     
         15 . The screw as claimed in  claim 3 , wherein, said positioning member is formed by a plurality of inclined wails that are recessed inwards from said cutting planes for forming a valley on said cutting planes, and each of said inclined walls and said cutting edge are converged at a point.