Drill bit and cutting head for drill bit

Patent metadata

Field	Value
Publication number	US-9284787-B2
Application number	US-201313901917-A
Country	US
Kind code	B2
Filing date	May 24, 2013
Priority date	May 29, 2012
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A cutting head for a drill bit comprises four substantially identically shaped cutting arms extending radially from a common central axial point, each cutting arm comprising a cutting edge extending, outwardly and axially backwards from the common central axial point. The cutting edges are equianguiarly spaced apart from each other about the central axis of the cutting head. Each cutting, arm further comprises a side chamfer extending between its radially outer face and its rotationally trailing side face.

First claim

What is claimed is:

1. A cutting head. for a drill bit, the cutting head comprising:
a front end portion centered on a central axis of the cutting head; and
at least four substantially identically shaped cutting arms extending radially outward from the front end portion a substantially identical radial distance from the central axis, and being substantially equiangularly spaced apart from each other about the central axis, each cutting arm including
a cutting edge extending generally radially outward from the front end portion,
a radially outer face extending generally axially rearward from a radially outermost end of the cutting edge,
a leading face extending generally radially outward from, the front end portion and generally axially rearward of the cutting edge, and facing a rotational drilling direction of the cutting head,
a trailing face extending generally radially outward from the front end portion and generally axially rearward of the cutting edge, and facing away from the rotational drilling direction of the cutting head, and
a side chamfer surface extending at an angle between the radially outer face and the trailing face.

2. The cutting head of claim 1 , wherein a projection of each cutting edge onto a plane perpendicular to the central axis is a straight unbroken line.

3. The cutting head of claim 1 , wherein each cutting edge comprises at least a first section, a second section, and a third section, wherein a first point angle is defined between the first section on a first of the cutting arms and the first section on a second of the cutting arms, a second point angle is defined between the second section on the first of the cutting arms and the second section on the second of the cutting arms, and a third point angle is defined between the third section on the first of the cutting arms and the third section on the second of the cutting arms, the first point angle being different from the second point angle, and the second point angle being different from the third point angle.

4. The cutting head of claim 3 , wherein in each of the cutting edges, the first section, the second section, and the third section is substantially straight and a first curved transition section extends between the first section and the second section, and a second curved transition section extends between the second section and the third section.

5. The cutting head of claim 3 , wherein each cutting edge further comprises a fourth section.

6. The cutting head of claim 5 , wherein the first point angle is between approximately 140° and approximately 150°, the second point angle is between approximately 105° and approximately 115°, the third point angle is between approximately 135° and approximately 145°, and the fourth point angle is between approximately 100° and approximately 110°.

7. The cutting head of claim 5 , wherein the first point angle is between approximately 95° and approximately 120°, the second point angle is between approximately 100° and approximately 120°, the third point angle is between approximately 135° and approximately 145°, and the fourth point angle is between approximately 100° and approximately 110°.

8. The cutting head of claim 5 , wherein the first section comprises approximately 17% to approximately 23% of the length of the cutting edge, the second section comprises approximately 8% to approximately 13% of the length of the cutting edge, the third section comprises approximately 22% to approximately 50% of the length of the cutting edge, and the fourth section comprises approximately 8% to approximately 13%, of the length of the cutting edge.

9. The cutting head of claim 1 , wherein each cutting arm further comprises a rake face extending axially rearward from the cutting edge to the leading face, and a relief face extending axially rearward from cutting edge to the trailing face, and the rake face and the relief face each include a plurality of side faces corresponding to a plurality of sections of the cutting edge.

10. The cutting head of claim 9 , wherein the rake face and the relief face of each cutting arm are angled symmetrically relative to a plane defined by the central axis and the cutting edge of the cutting arm.

11. The cutting head of claim 9 , wherein an internal angle between the rake face and the relief face of each cutting arm is between approximately 80° and approximately 90°.

12. The cutting head of claim 1 , wherein each cutting arm further comprises a rake face falling rearward from the cutting edge and a relief face falling rearward from cutting edge, each of the rake face and the relief face including a plurality of side faces corresponding to the sections of the cutting edge.

13. A cutting head for a drill bit, the cutting head comprising:
a front end portion centered on a central axis of the cutting head; and
at least four substantially identically shaped cutting arms extending radially outward from the front end portion a substantially identical radial distance from the central axis, and being substantially equiangularly spaced apart from each other about the central axis, each cutting arm including a cutting edge extending generally radially outward from the front end portion, each cutting edge including a first section, a second section, and a third section,
wherein a first point angle is defined between the first section on a first of the cutting arms and the first section on a second of the cutting arms, a second point angle is defined between the second section on the first of the cutting arms and the second section on the second of the cutting arms, and a third point angle is defined between the third section on the first of the cutting arms and the third section on the second of the cutting arms, the first point angle being different from the second point angle, and the second point angle being different from the third point angle.

14. The cutting head of claim 13 , wherein a projection of each cutting edge onto a plane perpendicular to the central axis is a straight unbroken line.

15. The cutting head of claim 13 , wherein, in each of the cutting edges, the first section, the second section, and the third section is substantially straight and a first curved transition section extends between the first section and the second section, and a second curved transition section extends between the second section and the third section.

16. The cutting head of claim 15 , wherein each cutting edge further comprises a fourth section, wherein a fourth point angle between the fourth section on the first of the cutting arms and the fourth section on the second of the cutting arms is different from at least one of the first point angle, the second point angle, and the third point angle.

17. The cutting head of claim 16 , wherein the first point angle is between approximately 140° and approximately 150°, the second point angle is between approximately 105° and approximately 115°, the third point angle is between approximately 135° and approximately 145°, and the fourth point angle is between approximately 100° and approximately 110°.

18. The cutting head of claim 16 , wherein the first point angle is between approximately 95° and approximately 120°, the second point angle is between approximately 110° and approximately 120°, the third point angle is between approximately 135° and approximately 145°, and the fourth point angle is between approximately 100° and approximately 110°.

19. The cutting head of claim 16 , wherein, in each cutting edge, the first section comprises approximately 17% to approximately 2

Assignees

• Black & Decker Inc

Inventors

• Hammer Andreas
• Brocket Steve
• Gastinger Christoph
• Bluemel Christian

Classifications

• B23B2251/44

  Margins, i.e. the narrow portion of the land which is not cut away to provide clearance on the circumferential surface · CPC title

• B23B51/02 Primary

  Twist drills · CPC title

• E21B10/58

  Chisel-type inserts ({E21B10/485,} E21B10/52 take precedence) · CPC title

• B23B2226/75

  Stone, rock or concrete · CPC title

• B23B2251/18

  Configuration of the drill point · CPC title