Rock drill

• US 4,951,761 A
• Filed: 05/31/1989
• Issued: 08/28/1990
• Est. Priority Date: 06/18/1988
• Status: Expired due to Term

• Current Assignee: Hawera Probst Gmbh (Robert Bosch GmbH)
• Original Assignee: Hawera Probst Gmbh (Robert Bosch GmbH)
• Inventors: Peetz, Wolfgang, Moser, Bernhard, Haussmann, August
• Primary Examiner(s): Novosad, Stephen J.
• Application Number:
  US07/359,122
• Time in Patent Office: 454 Days
• Field of Search: 175/410, 175/323, 175/394, 175/398, 175/400, 175/401, 175/415, 76/108 R, 76/108 A, 408/705
• US Class Current: 175/398
• CPC Class Codes: E21B 10/445 percussion type, e.g. for masonry
• CPC Class Codes: E21B 10/58 Chisel-type inserts E21B10/485, E21B10/52 take precedence

Abstract

A rock drill having a drilling head which, in an asymmetric arrangement relative to the main cutting tip, has at least one additional secondary cutting tip, the angle enclosed between the single cutting edge of the main cutting tip and the secondary cutting tip being formed as an acute angle.

Claims

1. A rock drill comprising a single-start or double-start conveying helix and a drilling head which has arranged on its end face pointing in the feed direction a carbide main cutting tip extending over the entire diameter of the drilling head, sloping in a roof shape and having two cutting edges, and at least one additional cutting element arranged asymmetrically relative to the cutting edges of the main cutting tip, wherein the additional cutting element is designed as a secondary cutting tip which has at least one cutting face and assumes an acute angle relative to the first cutting edge of the main cutting tip and an obtuse angle relative to the further cutting edge of the main cutting tip, and wherein the drilling head is designed in a V-shape, Y-shape or triangular shape in cross section, having at least two flat, V-shaped or concavely arched side flanks to form drilling-dust grooves.

2. The rock drill as claimed in claim 1, wherein the secondary cutting tip is designed as a cutting tip which slopes in a roof shape and has a center cutting point and two laterally arranged cutting edges.

3. The rock drill as claimed in claim 1, wherein the cutting edges of the main cutting tip and at the least the radially outer cutting edge of the secondary cutting tip lie on the same rotational cone arranged at the end face.

4. The rock drill as claimed in claim 1, wherein the secondary tip, relative to the single cutting edge of the main cutting tip which is located at an acute cutting angle, is arranged so as to be leading with regard to the direction of rotation of the drill.

5. The rock drill as claimed in claim 1, wherein the grooves for the main cutting tip and the secondary cutting tip extend over the entire diameter of the drilling head and run through the center point of the circumscribed circle of the drilling head.

6. The rock drill as claimed in claim 1, wherein the radial extent of the secondary cutting tip, with its outer single cutting edge, is the same as or less than the distance corresponding to the diameter of the main cutting edges.

7. The rock drill as claimed in claim 1, wherein the main cutting tip forms the angle bisector for the two side flanks.

8. The rock drill as claimed in claim 1, wherein the secondary tip forms an acute angle of about 40°

to 70°

relative to the trailing single cutting edge of the main cutting tip.

9. The rock drill as claimed in claim 1, wherein the drilling-head side connecting the V-shaped side flanks is designed as a semi-circular arc area which lies on the circumscribed circle of the drilling head.

10. The rock drill as claimed in claim 9, wherein the semi-circular arc area is cut off to form a triangular drilling-head cross section having an additional drilling-dust groove.

11. The rock drill as claimed in claim 1, wherein the drilling-head cross section is formed by an equilateral triangle on the circumscribed circle of the drilling head, having radiused corner areas arranged on the circumscribed circle of the drilling head.