Self-drilling screw structure and manufacturing method thereof
The invention provides a self-drilling screw structure and a manufacturing method thereof, wherein the manufacturing method includes: providing screw body, forming drill tail screw rod section, forming concave neck portion, forming drill tail cutting edge and forming thread. The self-drilling screw structure including a screw head portion and a screw rod portion, the screw rod portion is sequentially provided with a threaded screw rod section, a drill tail screw rod section and a drill bit screw rod section, the drill tail screw rod section has a rod diameter of drill tail, a plurality of drill tail cutting edges and a plurality of drill tail chip discharge grooves, the drill bit screw rod section is provided with a concave neck portion, and the drill bit screw rod section is protruded to form a plurality of drill bit cutting edges and the plurality of drill bit chip discharge grooves.
1. A self-drilling screw structure, comprising:
a screw head portion; and
a screw rod portion extending from the screw head portion, wherein a threaded screw rod section, a drill tail screw rod section and a drill bit screw rod section are sequentially formed at the screw rod portion from a side of the screw head portion along an axial direction, the threaded screw rod section has a rod diameter of thread and a thread protruding on the threaded screw rod section, the drill tail screw rod section has a rod diameter of drill tail, a plurality of drill tail cutting edges protrudes on the drill tail screw rod section, and a plurality of drill tail chip discharge grooves are located between the adjacent drill tail cutting edges, the plurality of drill tail cutting edges each have a major diameter of drill tail cutting edge, the drill bit screw rod section is sequentially provided with a concave neck portion, a positioning portion and a tip portion from the end adjacent to the drill tail screw rod section along the axial direction, a chisel point is formed by tapering from the end of the tip portion adjacent to the positioning portion to the other end along the axial direction, the concave neck portion is recessed from the end adjacent to the drill tail screw rod section to an end adjacent to the positioning portion along the axial direction to form an arc surface, the drill bit screw rod section forms a plurality of drill bit cutting edges and a plurality of drill bit chip discharge grooves by protruding from the chisel point toward the concave neck portion along the axial direction, and the plurality of drill bit chip discharge grooves are located between the adjacent drill bit cutting edges;
wherein the rod diameter of drill tail is less than the rod diameter of thread and is greater than zero;
wherein the major diameter of drill tail cutting edge is substantially equal to a major diameter of thread; and
wherein one end of the concave neck portion is connected with the plurality of drill tail cutting edges, and the other end is connected with the plurality of drill bit cutting edges.
2. The self-drilling screw structure according to claim 1 , wherein the concave neck portion of the drill bit screw rod section respectively gradually expands toward the drill tail screw rod section and the positioning portion along the axial direction, and the drill bit chip discharge grooves extend to part of the concave neck portion from the chisel point through the tip portion and the positioning portion.
3. The self-drilling screw structure according to claim 1 , wherein the plurality of drill tail cutting edges each have a first helical surface, a second helical surface and a drill tail helix angle, and the drill tail helix angle is formed at joint of the first helical surface and the second helical surface.
4. The self-drilling screw structure according to claim 3 , wherein the plurality of drill tail cutting edges are asymmetric structures, and a first distance on the first helical surfaces each of the drill tail cutting edges from the drill tail helix angle to surface of the drill tail screw rod section is greater than zero, and the first distance is less than a second distance on the second helical surfaces from the drill tail helix angle to surface of the drill tail screw rod section.