Sawtooth structure with reversed cutting function and its drill series

Patent metadata

Field	Value
Publication number	US-10857601-B2
Application number	US-201615750677-A
Country	US
Kind code	B2
Filing date	Aug 18, 2016
Priority date	Aug 18, 2015
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

A kind of sawtooth structure with reversed cutting function and its drill series are presented in this invention. This invention is suitable for drilling low-damage holes on carbon fiber reinforced polymers (CFRP). The sawtooth structure is comprised of sawteeth and grooves located on the cutting edges of drill. And the sawtooth structure is helically arranged with a specific helix angle around the axis of the drill. It can be classified as the left-hand helix sawtooth structure and the right-hand helix sawtooth structure based on the helix angle value. The bottom edges of the left-hand helix sawtooth structure are the cutting edges, and the rake angles are positive; while the top edges of the right-hand helix sawtooth are the cutting edge with the positive rake angles. The sawtooth structure can be applied to various drilling tools, which proves to be universal. And it can effectively reduce delamination at both hole entrance and hole exit as well as burrs defects. The series of drilling tools include the double point angle drill, the twist drill and the stepped drill all of which have the sawtooth structure on the cutting edges. These series of drilling tools can achieve the CFRP holes with minimum drilling defects. The drilling performance of the tools is improved to a great extent, the tool life is extended and the costs are reduced.

First claim

We claim:

1. A sawtooth structure with reversed cutting function has characteristics as below: the sawtooth structure is constructed by sawteeth ( 1 - 1 ) and grooves ( 1 - 2 ) located on cutting edges of a drill; the sawteeth ( 1 - 1 ) and the grooves ( 1 - 2 ) are helically arranged around a drill axis; the sawtooth structure is classified as left-hand helix sawtooth structure and right-hand helix sawtooth structure based on a helix angle ( 1 -β) of the sawtooth structure; the sawteeth ( 1 - 1 ) with the helix angle ( 1 -β) larger than 60° and smaller than 90° _are categorized as right-hand sawteeth, and top edges ( 1 - 3 ) of the right-hand sawteeth are additional cutting edges that are ground into positive rake angles ( 1 -γ 0 u ); the sawteeth ( 1 - 1 ) with the helix angle ( 1 -β) smaller than 150° and no less than 90° are categorized as left-hand sawteeth, and bottom edges ( 1 - 4 ) of the left-hand sawteeth are additional cutting edges that are ground into positive rake angles ( 1 -γ 0 d ); the sawtooth structure is located on cutting edges of which diameters are equal to 0.6 to 1 time of the diameter of a drill, and for step a drilling structure, the sawtooth structure is located on a step minor cutting edge; a length of sawteeth ( 1 -Lt) is not larger than the length of a drilling margin and is at least 0.8 mm; a width of grooves ( 1 -Wg) is at least 0.3 mm; a width of sawteeth ( 1 -Wt) is at least 0.5 mm; a depth of grooves ( 1 -Dt) is at least 0.8 mm, and the sawteeth ( 1 - 1 ) at a minimum diameter position cannot interfere with a drilling core.

2. The sawtooth structure with reversed cutting function according to claim 1 , wherein an intersecting-sawtooth double point angle drill consisting of the sawtooth structure with reversed cutting function, the right-hand and left-hand helix sawtooth structures are under intersecting arrangement; the right-hand and left-hand sawteeth are located on the cutting edges of the intersecting-sawtooth double point angle drill with four flutes; a intersecting sawtooth cutting zone ( 2 -E) is arranged at ends of four secondary cutting edges ( 2 - 2 ) within a secondary cutting zone ( 2 -B) and at fronts of four minor cutting edges ( 2 - 3 ) within a minor cutting zone ( 2 -C); the intersecting sawtooth cutting zone ( 2 -E) is constructed by the sawtooth structure arranged on separate cutting edges; the profiles of sawteeth ( 1 - 1 ) and grooves ( 1 - 2 ) remain the same on one cutting edge-; the number of sawteeth ( 1 - 1 ) along one cutting edge is 3 - 7 , and the number is identical on all cutting edges; helix angles of sawteeth ( 1 - 1 ) and grooves ( 1 - 2 ) are different on two adjacent cutting edges while the helix angles of sawteeth ( 1 - 1 ) and grooves ( 1 - 2 ) are identical on two opposite cutting edges; a helix angle ( 2 -βR) of sawteeth ( 1 - 1 ) on one set of cutting edges is right-hand acute angle larger than 60°, and top edges ( 1 - 3 ) are additional cutting edges which are ground into positive rake angles ( 1 -γ 0 u ); a helix angle ( 2 -βL) of sawteeth ( 1 - 1 ) on another set of cutting edges is right angle or left-hand obtuse angle less than 150°, and the bottom edges ( 1 - 4 ) are additional cutting edges which are ground into positive rake angles ( 1 -γ 0 d ); the above stated right-hand and left-hand sawteeth form the intersecting sawtooth cutting zone ( 2 -E) on two adjacent cutting edges.

3. The sawtooth structure with reversed cutting function according to claim 1 , wherein a right-hand sawtooth double point angle drill consisting of the sawtooth structure with reversed cutting function, the right-hand sawteeth are helically arranged on the cutting edges of the right-hand sawtooth double point angle drill with four flutes, and a sawtooth cutting zone ( 3 -E) is arranged at fronts of four secondary cutting edges wherein a secondary cutting zone ( 3 -B) and ends of four minor cutting edges at a minor cutting zone ( 3 -C); the sawtooth cutting zone ( 3 -E) is constructed by the sawtooth structure located on separate cutting edges; the number of sawteeth ( 1 - 1 ) on each secondary cutting edge is 1 to 3 and the number of sawteeth ( 1 - 1 ) on each minor cutting edge is 2 to 4; a helix angle ( 1 -β) of the sawtooth structure of all the sawteeth ( 1 - 1 ) is right-hand acute angle larger than 60° and top edges ( 1 - 3 ) on the sawteeth ( 1 - 1 ) are additional cutting edges that are ground into positive rake angles ( 1 -γ 0 u ).

4. The sawtooth structure with reversed cutting function according to claim 1 , wherein a right-hand sawtooth twist drill consisting of a sawtooth structure with reversed cutting function, the right-hand sawteeth are arranged on minor cutting edges; a point angle ( 4 -α) of the right-hand sawtooth twist drill is 85°-90°, and the length of a chisel edge is 0.1-0.6 mm, a rake angle ( 4 -γ 0 ) of primary cutting edges ( 4 - 1 ) of the right-hand sawtooth twist drill is ground into fixed value and the rake angle ( 4 -γ 0 ) is 15°-20°, a first flank angle ( 4 -α 1 ) on the primary cutting edges ( 4 - 1 ) is 10°-12° and a second flank angle ( 4 -α 2 ) on the primary cutting edges ( 4 - 1 ) is 15°-25°, the area of a second flank face ( 4 - 8 ) is 3 to 5 times larger than the area of a first flank face ( 4 - 7 ); a helix angle of the flutes of the right-hand sawtooth twist drill is 30°-34°; a sawtooth cutting zone ( 4 -D) is located on minor cutting edges ( 4 - 2 ) of the right-hand sawtooth twist drill within a minor cutting zone ( 4 -B); the number of sawteeth ( 1 - 1 ) on each minor cutting edge ( 4 - 2 ) is 3 - 5 and the number is identical on all the minor cutting edges ( 4 - 2 ); a distance ( 4 - d ) between the sawteeth close to a drill point and a primary cutting zone ( 4 -A) is 1-1.5 mm; the sawteeth ( 1 - 1 ) and the grooves ( 1 - 2 ) are helically arranged around a drill axis ( 4 - 4 ) and the helix angle ( 1 -β) of the sawtooth structure is acute angle larger than 60°; the top edges ( 1 - 3 ) of the sawteeth ( 1 - 1 ) are additional cutting edges that are ground into positive rake angles ( 1 -γ 0 u ).

5. The sawtooth structure with reversed cutting function according to claim 1 , wherein a right-hand sawtooth step drill consisting of the sawtooth structure with reversed cutting function, the right-hand sawteeth are arranged on step minor cutting edge of the right-hand sawtooth step drill; a step cutting zone ( 5 -A) is constructed by n levels of step structures, wherein n is a number ≥2; each step structure is comprised of a primary step cutting zone and a minor step cutting zone; a Level j step structure is a part of the n levels of step structures; a sawtooth cutting zone ( 5 -D) is located on the step cutting zone ( 5 -A) and the sawtooth cutting zone ( 5 -D) is constructed by n levels of sawtooth structure; then levels of sawtooth structures are arranged in the direction from a drill point to a clamping zone ( 5 -C); a Level j sawtooth structure is a part of the n levels of sawtooth structures and is located on a minor cutting zone of the Level j step structure, wherein j is a number ≥n.

6. The sawtooth structure with reversed cutting function according to claim 5 , wherein a nominal diameter difference between Level j and Level j−1 step structures is 20% to 40% of a nominal diameter of the Level j step structure, where 2≤j≤n; at least two sawteeth ( 1 - 1 ) are distributed along an axial direction of a step minor cutting edge of the Level j step structure for the right-hand sawtooth step drill, wherein j is a number >2; a point angle of the Level j step structure is 80°-100°, wherein j=1; a point angle of the Level j step structure is 60°-80°, and the point angle of the Level j step structure is smaller than that of a Level j−1 step structure, wherein j is a number ≥2; a rake angle of primary cutting edges of each st

Assignees

• Univ Dalian Tech

Inventors

• Jia Zhenyuan
• Wang Fuji
• Fu Rao
• Bai Yu
• Niu Bin
• Liu Wei
• Ma Jianwei
• He Chunling

Classifications

• B23B2226/275

  Carbon fibre reinforced carbon composites · CPC title

• B23B51/02

  Twist drills · CPC title

• B23B51/08

  Drills combined with tool parts or tools for performing additional working {(B23G5/20 takes precedence)} · CPC title

• B23B51/009 Primary

  Stepped drills · CPC title

• B23B2251/285

  Cutting teeth arranged at different heights · CPC title