Twist drill

• US 20050135887A1
• Filed: 12/17/2003
• Published: 06/23/2005
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: Kennametal Incorporated
• Original Assignee: Kennametal Incorporated
• Inventors: Krieg, Tilo, Borschert, Bernhard W., Shultz, Michael D., Meenan, Larry R., Hanna, Jerome C.
• Granted Patent: US 7,101,125 B2
• Time in Patent Office: Days
• US Class Current: 408/230
• CPC Class Codes: B23B 2250/12 Cooling and lubrication
• CPC Class Codes: B23B 2251/046 Variable
• CPC Class Codes: B23B 2251/402 with increasing depth in a direction towards the shank from the tool tip
• CPC Class Codes: B23B 2251/50 Drilling tools comprising cutting inserts
• CPC Class Codes: B23B 51/02 Twist drills
• CPC Class Codes: Y10T 408/9097 Spiral channel

Abstract

A twist drill including a cutting tip having a front flank face, a substantially cylindrical tool body extending rearwardly from the cutting tip, and a shank. The tool body includes a rotational axis therethrough and at least one flute formed on an outer peripheral surface thereof and extending to the front flank face. The at least one flute includes a first helical portion opening to the front flank face and a second helical portion extending from the rear end of the first helical portion toward the rear portion of the tool body. The second helical portion twists in a direction opposite of the first helical portion.

Claims

1. A twist drill comprising:

a cutting tip including a front flank face, a substantially cylindrical tool body extending rearwardly from the cutting tip, and a shank;

the tool body having a rotational axis therethrough and including at least one flute formed on an outer peripheral surface thereof and extending to the front flank face;

wherein the at least one flute includes a first helical portion opening to the front flank face and a second helical portion extending from the rear end of the first helical portion toward the rear portion of the tool body, wherein the second helical portion twists in a direction opposite of the first helical portion.

2. The twist drill of claim 1 wherein the first helical portion is positioned in a positive helix.

3. The twist drill of claim 1 wherein the cutting tip is an interchangeable cutting tip.

4. The twist drill of claim 1 wherein the cutting tip includes an S-shaped chisel edge.

5. The twist drill of claim 1 wherein the tool body is made of steel.

6. The twist drill of claim 1 wherein the tool body is made of cemented carbide.

7. The twist drill of claim 1 wherein the tool body includes a pair of helical flutes formed in a peripheral outer surface of the tool body.

8. The twist drill of claim 7 wherein the helix angle of the first helical portion is maintained constant from the cutting tip to the tool body and on a portion of the flutes in the tool body.

9. The twist drill of claim 1 wherein the twist drill includes at least one coolant hole.

10. The twist drill of claim 1 wherein the helix angle of the first helical portion is about 0 to about 40 degrees.

11. The twist drill of claim 10 wherein the helix angle of the first helical portion is about 30 degrees.

12. The twist drill of claim 1 wherein the helix angle of the second helical portion is from about 1 to about 30 degrees.

13. The twist drill of claim 12 wherein the helix angle of the second helical portion is about 3 degrees.

14. The twist drill of claim 1 further comprising a third helical portion extending from the rear of the second helical portion.

15. The twist drill of claim 14 wherein the third helical portion twists in a direction opposite of the second helical portion.

16. The twist drill of claim 15 wherein the third helical portion extends from the rear of the second helical portion to the shank of the drill.

17. The twist drill of claim 14 wherein the helix angle of the third helical portion is constant.

18. The twist drill of claim 14 wherein the helix angle of the third helical portion is from about 0 to about 40 degrees.

19. The twist drill of claim 14 wherein the helix angle of the third helical portion is about 5 degrees.

20. The twist drill of claim 1 wherein the twist drill has web thickness that is constant along the length of the twist drill.

21. The twist drill of claim 1 wherein the twist drill has a web thickness that is tapered along the length of the twist drill.

22. The twist drill of claim 1 wherein the twist drill has a web thickness that varies along the longitudinal length of the twist drill.