DRILL BIT

• US 20120076597A1
• Filed: 06/08/2010
• Published: 03/29/2012
• Est. Priority Date: 06/08/2009
• Status: Active Grant

• Current Assignee: Mapal Fabrik fuer Praezisionswerkzeuge Dr Kress KG (MAPAL Holding GmbH)
• Original Assignee: Mapal Fabrik Fur Prazisionswerkzeuge Dr. Kress Dg
• Inventors: Krenzer, Ulrich, Marz, Peter
• Granted Patent: US 8,801,344 B2
• Time in Patent Office: Days
• US Class Current: 408/227
• CPC Class Codes: B23B 2251/04 Angles, e.g. cutting angles
• CPC Class Codes: B23B 2251/18 Configuration of the drill point
• CPC Class Codes: B23B 2251/70 Drills with vibration suppressing means
• CPC Class Codes: B23B 51/02 Twist drills
• CPC Class Codes: Y10T 408/909 Having peripherally spaced cutting edges
• CPC Class Codes: Y10T 408/9097 Spiral channel

Abstract

The invention proposes a drill bit (1) leaving at least one main cutting edge (3, 3′) and at least one center cutting edge (15, 15′), wherein the drill bit (1) comprises a longitudinal axis (13), and wherein the at least one main cutting edge (3, 3′) and the at least one center cutting edge (15, 15′) are each assigned a rake face (7, 7′, 11, 11′). The drill bit (1) is characterized in that the rake face (11, 11′) assigned to the at least one center cutting edge (15, 15′) has at least two part faces (19, 19′; 21, 21′) which—as seen as perpendicular to the longitudinal axis (13) of the drill bit (1)—form an obtuse angle with one another, so that the at least one center cutting edge (15, 15′) comprises at least two part cutting edges (23, 23′; 25, 25′).

Claims

1. Drill bit with at least one main cutting edge (3, 3′

) and at least one center cutting edge (15, 15′

), wherein the drill bit (1) has a longitudinal axis (13) and wherein a rake face (7, 7′

;

11, 11′

) is assigned to the at least one main cutting edge (3, 3′

) and at least one center cutting edge (15, 15′

), characterized in that the rake face (11, 11′

) assigned to the at least one center cutting edge (15, 15′

) has at least two partial faces (19, 19′

;

21;

21′

;

41;

41′

) that—

seen perpendicular to the longitudinal axis (13) of the drill bit (1)—

form an obtuse angle with each other so the at least one center cutting edge (15, 15′

) comprises at least two partial cutting edges (23, 23′

;

25, 25′

;

43, 43′

).

2. Drill bit according to claim 1, characterized in that a lateral boundary surfaces (27, 29, 37) is assigned to the rake face (7, 7′

) of the main cutting edge (3, 3′

) and at least two partial faces (19, 19′

;

21;

21′

;

41;

41′

) of the rake face (11, 11′

) of the center cutting edge (15, 15′

).

3. Drill bit according to claim 2, characterized in that the rake face (7, 7′

) and/or the partial faces (19, 19′

;

21;

21′

;

41;

41′

) each form different angles with each of the lateral boundary surfaces (27, 29, 37) assigned to them.

4. Drill bit according to claim 3, characterized in that the angles formed by the rake face (7, 7′

) and/or the partial faces (19, 19′

;

21;

21′

;

41;

41′

) with the lateral boundary surfaces (27, 29, 37) assigned to them assume values between 60° and

140°

, preferably 70° and

130° and

in an especially preferred manner between 80° and

120°

.

5. Drill bit according to claim 4, characterized in that the angles are approximately 100°

.

6. Drill bit according to claim 2, characterized in that the lateral boundary surfaces (27, 29, 37) each form an acute angle with the longitudinal axis (13) of the drill bit (1), the value of which increases with increasing radial distance with respect to the longitudinal axis (13) of the drill bit (1) of the rake and/or partial faces (7, 7′

;

19, 19′

;

21;

21′

;

41;

41′

) assigned to the lateral boundary surfaces (27, 29, 37).

7. Drill bit according to claim 1, characterized in that a front rake angle is assigned to the one main cutting edge (3, 3′

) and the at least two partial cutting edges (19, 19′

;

21;

21′

;

41;

41′

) of the center cutting edge (15, 15′

) that has a value that increases with increasing radial distance of the assigned main cutting edge and/or partial cutting edge (3, 3′

;

23, 23′

;

25, 25′

;

43, 43′

) with respect to the longitudinal axis of the drill bit (1).

8. Drill bit according to claim 1, characterized in that at least the front rake angle assigned to the partial cutting edge (19, 19′

;

21;

21′

;

41;

41′

) arranged next with respect to the longitudinal axis (13) of the drill bit (1) has a negative value.

9. Drill bit according to claim 2, characterized in that transitions between the rake face and/or partial faces (7, 7′

;

19, 19′

;

21;

21′

;

41;

41′

) and/or the lateral boundary surfaces (27, 29, 37) are designed so they are rounded.

10. Drill bit according to claim 9, characterized in that the roundings of the transitions have an increasing radius with increasing radial distance of the rake and/or partial face (7, 7′

;

19, 19′

;

21;

21′

;

41;

41′

) assigned to a transition from the longitudinal axis (13) of the drill bit (1).

11. Drill bit according to claim 1, characterized in that the transitions between the main cutting edge (3, 3′

) and the center cutting edge (15, 15′

) and/or between the at least two partial cutting edges (23, 23′

;

25, 25′

;

43, 43′

) of the center cutting edge (15, 15′

) are designed so they are rounded.

12. Drill bit according to claim 1, characterized in that the rake surface (11, 11′

) assigned to the at least one center cutting edge (15, 15′

) has three partial faces (19, 19′

;

21;

21′

;

41;

41′

) so that the at least one center cutting edge (15, 15′

) has at least three partial cutting edges (23, 23′

;

25, 25′

;

43, 43′

).