Multi-lip drilling tool with internal cooling ducts

Patent metadata

Field	Value
Publication number	US-9636756-B2
Application number	US-201514847471-A
Country	US
Kind code	B2
Filing date	Sep 8, 2015
Priority date	Mar 21, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A multi-lip drilling tool is described, in which main cutting edge transitions in the region of the drill into a center lip section, wherein a cooling duct that leads to the drill tip is formed in each drill web. The invention minimizes tensile stress spikes in the chip flute base, while at the same time ensuring that a hitherto unachievable coolant/lubricant quantity gets to the engaged main blade. This is ensured by selecting a duct cross sectional form similar to an unsymmetrical kidney, in which it is ensured the selected radii of curvature for the individual boundary curve sections causes as much coolant/lubricant as possible to arrive at the blade or in proximity thereto in the fastest way via the point thinning and its edges intersecting with drill core.

First claim

The invention claimed is:

1. A multi-lip drilling tool with internal cooling ducts and point grinding with point thinning, in which a main cutting edge transitions into a central cutting edge section in the area of the drill core, wherein a cooling duct guided to the drill hit is formed in each drill web, and the cooling duct has the following characteristics as viewed in the cross section of the drill:
a) It has the cross sectional form of an unsymmetrical kidney, wherein
b) the largest circle (KE) essentially inscribed in the cooling duct cross section overlaps with the center of the drill webs and bounds the contour of the cooling duct cross section via a central angle (WZKE) in a range of between 80 and 90° in a radially external region (KEZW) facing away from the rotational direction;
c) radially externally and in the cutting direction, the boundary curve (KEZW) defined by the inscribed circle (KE) is adjoined essentially in the circumferential direction by a cross sectional contour section (BQ 1 ), whose radius of curvature (R 1 ) has the same direction as, but is significantly smaller than, the inscribed circle (KE);
d) the smaller radius of curvature (R 1 ) of the cross sectional contour section BQ 1 transitions into a concave curve (KK) with a radius of curvature (R 2 ) that is many times larger than the curvature of the inscribed largest circle (KE);
e) radially internally and outside the inscribed largest circle (KE), the concave curve (KK) is once again adjoined by a convex duct bulging section (AKA) with a radius of curvature (R 3 ) that is significantly greater than the small radius of curvature (R 1 ) in the cross sectional contour section (BQ 1 ); and
f) the curvature of the cross sectional boundary continuously increases from the bulging section (AKA) to the region KEZW.

2. The drilling tool according to claim 1 , wherein the largest circle (KE) essentially inscribed in the cooling duct cross section lies essentially in the center of the drill webs.

3. The drilling tool according to claim 1 , wherein the largest circle (KE) essentially inscribed in the cooling duct cross section intersects the concave curve (KK) at two points.

4. The drilling tool according to claim 1 , wherein the cooling duct in the drill web extends over a central angle (WZKK) of between 30 and 40° .

5. The drilling tool according to one of claim 1 , wherein the cooling duct in the drill web extends in a radial direction over an area (BR) ranging between 0.15 and 0.2×D, wherein D denotes the nominal diameter (DN) of the drilling tool.

6. The drilling tool according to claim 1 , wherein the central point of the largest inscribed circle (KE) lies on a semicircle having a diameter (DTK) ranging between 0.45 to 0.55×D, wherein D denotes the nominal diameter (DN) of the drilling tool.

7. The drilling tool according to one of claim 1 , wherein the diameter (DKE) of the inscribed largest circle (KE) ranges between 0.1 and 0.15×D, wherein D denotes the nominal diameter (DN) of the drilling tool.

8. The drilling tool according to of claim 1 , wherein the smaller radius of curvature (R 1 ) of the cross sectional contour section BQ 1 has a value essentially corresponding to 0.25 times the diameter (DKE) of the inscribed largest circle (KE).

9. The drilling tool according to claim 1 , wherein the radius of curvature (R 2 ) of the concave curve (KK) essentially corresponds to twice the value of the diameter (DKE) of the inscribed largest circle (KE).

10. The drilling tool according to one of claim 1 , wherein the radius of curvature (R 3 ) of the convex duct bulging section (AKA) essentially corresponds to 1.5 times the smallest radius of curvature (R 1 ) in the cross sectional contour section BQ 1 .

11. The drilling tool according to one of claim 1 , wherein at least sections of the main blade are concave in design extending from the cutting edge.

12. The drilling tool according to one of claim 1 , wherein the main blade has an inflection point in the area of transition to the central blade section.

13. The drilling tool according to one of claim 1 , wherein the cooling duct empties partially into the free surface and into a base of the point thinning.

14. The drilling tool according to claim 1 , characterized by a configuration as a tool for drilling into solid materials.

Assignees

• Guehring Kg
• Guehring Kg

Inventors

• Riester Christine

Classifications

• Y10T408/455

  Conducting channel extending to end of Tool · CPC title

• B23B51/06 Primary

  Drills with lubricating or cooling equipment {(B23B51/042 takes precedence)} · CPC title

• B23B2250/12

  Cooling and lubrication · CPC title