Hard metal drill bit for use on a drill

• US 6,629,805 B1
• Filed: 06/05/2001
• Issued: 10/07/2003
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: Karl Eischeid
• Original Assignee: Karl Eischeid
• Inventors: Eischeid, Karl
• Primary Examiner(s): TSAI, HENRY
• Application Number:
  US09/807,568
• Time in Patent Office: 854 Days
• Field of Search: 408/226, 408/227, 408/228, 408/229, 408/230, 408/144, 408/145, 408/713, 407/113, 407/114, 407/115, 407/116
• US Class Current: 408/228
• CPC Class Codes: B23B 2226/75 Stone, rock or concrete working of stone B28D
• CPC Class Codes: B23B 2251/04 Angles, e.g. cutting angles
• CPC Class Codes: B23B 2251/14 Configuration of the cutting part, i.e. the main cutting edges
• CPC Class Codes: B23B 2251/50 Drilling tools comprising cutting inserts
• CPC Class Codes: B23B 51/00 Tools for drilling machines
• CPC Class Codes: B23B 51/00035 Spade drills
• CPC Class Codes: B23B 51/02 Twist drills
• CPC Class Codes: Y10T 408/9093 Each formed by a pair of axially facing facets
• CPC Class Codes: Y10T 408/9097 Spiral channel

Abstract

The invention concerns a hard-metal cutting tip for use on a drill, particularly on a rock or concrete drill, including a drill point (3) extending through an axis of rotation of the drill, primary cutting edges (6) that slope downwardly on both sides, each composed of a primary land (4) and a primary flank (5), the primary flank (5) forming at the primary cutting edge (6) a primary lip clearance angle (14) with a plane perpendicular to the axis of rotation. To provide a hard-metal cutting tip that possesses high cutting, feed, bending and breaking strength and wear resistance, especially at its outer regions subjected to high peripheral speeds, the hard-metal cutting tip is realized such that the primary lip clearance angle (14) formed at the primary cutting edge (6) decreases with increasing distance from the drill point (3).

Claims

1. A hard-metal cutting tip for use on a drill (1), the cutting tip comprising a drill point (3) extending through an, axis (2) of rotation of the drill (1), and primary cutting edges (6) that slope downwardly on both sides, each cutting edge being composed of a primary land (4) and a primary flank (5), said primary flank (5) being inclined to a plane (12) perpendicular to the axis (2) of rotation to form a primary lip clearance angle (14), characterized in that the primary lip clearance-angle (14) decreases with increasing distance (15) from said drill point (3), wherein said primary flank (5) transitions to a conical transitional face (50) between said primary flank (5) and a small-side face (8), there being a change in an angle (21) of said primary cutting edge (6) at a distance (17) from said drill point (3), and wherein said small-side face (8) has an outer radius (7) adjoined by a flank (30) that is disposed thereafter in a direction of cutting motion (33) and that broadens with increasing distance from an outer edge (24).

2. The hard-metal cutting tip as recited in claim 1, characterized in that the decrease in said primary lip clearance angle (14) is constant.

3. The hard-metal cutting tip as recited in claim 2, characterized in that the decrease in the primary lip clearance angle (14) begins at a defined distance (16) from said drill point (3).

4. The hard-metal cutting tip as recited in claim 1, characterized in that said drill point (3) has a point angle (1.8) that is smaller than the angle (21) of said primary cutting edges (6) near the transitional face (50).

5. The hard-metal cutting tip as recited in claim 1, characterized in that each of said primary flanks (5) transitions to said drill point (3) by means of a chamfer (38).

6. The hard-metal cutting tip as recited in claim 1, wherein the drill comprises a selected one of a rock drill and a concrete drill.