DRILL BIT WITH A REPLACEABLE CUTTING PORTION

Abstract

A drill bit rotatable about a rotation axis is disclosed. The drill bit has a first drill bit portion configured as a cutting portion and has an annular portion connected at one end to one or more cutting elements and, at another end, a first connection device. The drill bit has a second drill bit portion configured as a drilling shank portion and has a cylindrical drill shaft, which on one end has a second connection device. The first and second connection devices in a connected state form a detachable connection, and a force transmission and torque transmission occur from the drill shaft portion to the cutting portion. The cutting portion has a third connection device, and the drill shaft portion has a fourth connection device. The third and fourth connection devices in a connected state form in an axial direction parallel to the axis a form-fitting connection.

Claims

1.-13. (canceled)

14. A drill bit, wherein the drill bit is rotatable about an axis of rotation, comprising: a first drill bit portion configured as a cutting portion, having an annular portion that is connected at one end to one or more cutting elements and, at another end, a first connection device; and a second drill bit portion configured as a drill shaft portion, having a cylindrical drill shaft, which on one end facing the cutting portion has a second connection device, wherein the first and second connection devices in a connected state form a detachable connection between the cutting portion and the drill shaft portion, and via the first and second connection devices, a force transmission and torque transmission occur from the drill shaft portion to the cutting portion, wherein the cutting portion has a third connection device different from the first connection device, and the drill shaft portion has a fourth connection device different from the second connection device, and wherein the third and fourth connection devices in a connected state form in an axial direction parallel to the axis of rotation a form-fitting connection between the cutting portion and the drill shaft portion.

15. The drill bit according to claim 14, wherein the third and fourth connection devices have a tongue and a groove, and the tongue is moveable in the groove.

16. The drill bit according to claim 14, wherein the first and second drill bit portions comprise an inner plug element and an outer plug element, and wherein the inner and outer plug elements form a plug connection when in the connected state.

17. The drill bit according to claim 16, wherein an end face of the inner plug element abuts a limit stop shoulder of the outer plug element when in the connected state.

18. The drill bit according to claim 16, wherein the outer plug element is provided on the cutting portion and the inner plug element is provided on the drill shaft portion.

19. The drill bit according to claim 16, wherein the first and second connection devices have at least one pin element and at least one slit-shaped recess, and the pin element is moveable into the slit-shaped recess.

20. The drill bit according to claim 19, further comprising at least one pin element arranged on an outer side of the inner plug element, and the outer plug element has the at least one slit-shaped recess.

21. The drill bit according to claim 20, wherein the at least one slit-shaped recess completely penetrates the outer plug element in a radial direction perpendicular to the axis of rotation.

22. The drill bit according to claim 20, further comprising three or more pin elements arranged on the outer side of the inner plug element, and the outer plug element has three or more slit-shaped recesses, wherein the number of slit-shaped recesses is greater than or equal to the number of pin elements.

23. The drill bit according to claim 21, wherein the tongue is arranged on the outer side of the inner plug element, and the outer plug element has the groove.

24. The drill bit according to claim 23, wherein the tongue is arranged in an axial direction between the pin elements and the drill shaft, and the groove is arranged in an axial direction at the level of the slit-shaped recesses.

25. The drill bit according to claim 24, wherein the groove is designed in a ring-shaped manner and is arranged in a plane perpendicular to the axis of rotation.

26. The drill bit according to claim 15, wherein the axial height of the groove is at least 1 mm larger than the axial height of the tongue.

27. The drill bit according to claim 17, wherein the outer plug element is provided on the cutting portion and the inner plug element is provided on the drill shaft portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIGS. 1A, B depict a drill bit according to the invention with an exchangeable cutting portion and a drill shaft portion in a non-connected state (FIG. 1A) and in a connected state (FIG. 1B);

[0035] FIG. 2 depicts the drill shaft portion of the drill bit depicted in FIG. 1 in a longitudinal cross-section along sectional plane A-A in FIG. 1A;

[0036] FIG. 3 depicts the cutting portion of the drill bit depicted in FIG. 1 in a longitudinal cross-section along the sectional plane B-B in FIG. 1A (FIG. 3A); and

[0037] FIG. 4 depicts the cutting portion and the drill shaft portion in a connected stated in a longitudinal cross-section along sectional plane C-C in FIG. 1B.

DETAILED DESCRIPTION OF THE DRAWINGS

[0038] FIGS. 1A, B depict a drill bit 10 according to the invention with a cutting portion 11, which is connected via a detachable connection to a drill shaft portion 12. In doing so, FIG. 1A depicts cutting portion 11 and drill shaft portion 12 in a non-connected state with an open connection, and FIG. 1B depicts cutting portion 11 and drill shaft portion 12 in a connected stated with a closed connection.

[0039] Cutting portion 11 includes an annular portion 13, which is connected at one end facing away from drill shaft portion 12 to multiple cutting elements 14, and which has on an end facing drill shaft portion 12 a first connection device 15. Cutting elements 14 are welded, soldered, or screwed to annular portion 13, or attached by way of another suited attachment method to annular portion 13. Cutting portion 11 can have, instead of multiple cutting elements 14, also a single cutting element designed as a cutting sleeve, which is connected to annular portion 13.

[0040] Drill shaft portion 12 includes a cylindrical drill shaft 16, which has, on an end facing cutting portion 11, a second connection device 17, and which, on an end facing away from cutting portion 11, is connected to a receiving portion 18. Receiving portion 18 includes a cover 19 and an insertion end 20. Drill bit 10 is attached via insertion end 20 in the tool holder of a drilling device. During the drilling operation, drill bit 10 is driven in direction of rotation 21 about an axis of rotation 22 and moved in a drilling direction 23 parallel to axis of rotation 22 into the substrate to be worked on. Axis of rotation 22 runs coaxially to a longitudinal axis of drill shaft 16 and to a longitudinal axis of annular portion 13. Drill bit 10 has a circular cross-section perpendicular to axis of rotation 22. Alternatively, drill bits according to the invention may have other suitable cross-sections, such as a polygonal cross-section.

[0041] The first connection device 15 includes a first plug element 24, which is designed as an outer plug element, and six slit-shaped recesses 25, which are provided in the outer plug element. Second connection device 17 includes a second plug element 26, which is designed as an inner plug element, and six pin elements 27, which are attached on an outer side 28 of inner plug element 26 and are oriented radially outward.

[0042] In the connected state depicted in FIG. 1B, the first and second connection devices 15, 17 form a detachable connection between cutting portion 11 and drill shaft portion 12. By way of first and second connection devices 15, 17, the force transmission and torque transmission occur from drill shaft portion 12 to cutting portion 11.

[0043] Pin elements 27 and slit-shaped recesses 25 are arranged evenly about axis of rotation 22. By the even distribution, there is no allocation between pin elements 27 and slit-shaped recesses 25, and a pin element 27 can be inserted into any slit-shaped recess 25. Slit-shaped recesses 25 consist of a longitudinal slit, whose longitudinal axis is arranged parallel to axis of rotation 22. This shape of the slit-shaped recess is also referred to as an I-slit. In the depicted embodiment, pin elements 27 are designed in a rectangular manner. Alternatively, pin elements 27 can be circular, trapezoidal, or be designed in another suitable cross-sectional shape. Slit-shaped recesses 25 can alternatively be designed as L- or T-slits.

[0044] To support the force and torque transmission and to prevent individual regions from being overloaded, the contact region, through which the force and torque transmission from drill shaft portion 12 to cutting portion 11 occur, should not be point-shaped or line-shaped, but surface-shaped. The contact region can be adjusted by the cross-sectional shape of pin elements 27. In any event, the torque transmission occurs via pin elements 27, which strike a side-wall of I-slit 25 when drill shaft portion 12 is rotated. The force transmission can also occur via pin elements 27 or via a limit stop shoulder, which is struck by an end face 29 of inner plug element 26.

[0045] Cutting portion 11 has, besides first connection device 15, a third connection device 31, which is different from first connection device 15, and drill shaft portion 12 has, besides second connection device 17, a fourth connection device 32, which differs from second connection device 17. In a connected state of drill bit 10, third and fourth connection devices 31, 32 form in an axial direction a form-fitting connection between cutting portion 11 and drill shaft portion 12. Cutting portion 11 is protected against a removal of drill shaft portion 12 from cutting portion 11 by way of third and fourth connection devices 31, 32.

[0046] Third connection device 31 includes a groove 33, which is arranged on an inner side of outer plug element 24. Fourth connection device 32 includes a tongue 34, which is arranged on outer side 28 of inner plug element 26 and extends radially outward.

[0047] Cutting portion 11 can be connected to drill shaft portion 12 by the operator simply and quickly. To do so, cutting portion 11 with outer plug element 24 is placed on inner plug element 26 of drill shaft portion 12 in such a manner that pin elements 27 are arranged in slit-shaped recesses 25. Cutting portion 11 is moved in an axial direction until tongue 34 is latched into groove 33.

[0048] FIG. 2 depicts a section of drill shaft portion 12 of drill bit 10 according to the invention in a longitudinal cross-section along sectional plane A-A in FIG. 1A. Drill shaft portion 12 includes cylindrical drill shaft 16 and inner plug element 26, which are constructed in a monolithic manner. As an alternative to the monolithic design, inner plug element 26 may be constructed as a separate component and then be connected to drill shaft 16.

[0049] Inner plug element 26 includes an outer shell surface, which corresponds to outer side 28, the end surface 29, and an inner shell surface 35, on the transition from drill shaft 16 to inner plug element 26 there is a ring-shaped limit stop shoulder 36. On outer side 28 of inner plug element 26, there are arranged pin elements 27 and tongue 34. Pin elements 27, tongue 34, and inner plug element 26 may be produced of various materials and connected to each other or they consist of the same material, wherein pin elements 27 and tongue 34 may be created by forming processes, such as stamping or pressing.

[0050] Tongue 34 is arranged in an axial direction, i.e., in drilling direction 23, between pin elements 27 and limit stop shoulder 36 of inner plug element 26. To separate drill shaft portion 12 from cutting portion 11, a force is exerted in an axial direction on the end face of outer plug element 24 by way of a tool. By the application of force, the springy portion of outer plug element 24 is deflected and the form-fitting connection between tongue 34 and groove 33 can be disengaged. The greater the distance of groove 33 is to end face 29 of inner plug element 26, the greater the deflection of outer plug element 24.

[0051] FIG. 3 depicts cutting portion 11 of drill bit 10 according to the invention in a longitudinal cross-section along sectional plane B-B in FIG. 1A. Cutting portion 11 includes annular portion 13, cutting elements 14, and outer plug element 24. In the depicted embodiment, annular portion 13 and outer plug element 24 are constructed in a monolithic manner. As an alternative to the monolithic design, outer plug element 24 can be constructed as a separate component and then be connected to annular portion 13.

[0052] Cutting elements 14 are arranged in a plane perpendicular to axis of rotation 22 in a ring shaped manner about annular portion 13 and each have an outer edge 41 and an inner edge 42. Annular portion 13 connects in a bonded manner to inner edge 42 of cutting element 14 and has, relative to outer edge 41 of cutting element 14, a setback 43. Outer edges 41 of cutting elements 14 form an outer circle with an exterior diameter and the inner edges form an inner circle with an interior diameter. Cutting elements 14 create, in the substrate, a drill hole with a drill hole diameter which corresponds to the exterior diameter of cutting elements 14. Inside drill bit 10, a drill core is created with a drill core diameter, which corresponds to the interior diameter of the cutting elements.

[0053] Annular portion 13 includes on the inner side a guide portion 44 and a core removal portion 45. Core removal portion 45 has an inclined surface that assists the removal of the drill core. Guide portion 44 connects in a bonded manner to cutting element 14 and forms a guide for cutting elements 14 when drilling. As an alternative to the guide on the inner side of drill bit 10, the guide portion can be arranged on the outer side or on the outer and inner sides.

[0054] Outer plug element 24 includes an outer shell surface 46, an inner shell surface 47, and an end face 48. At the transition from annular portion 13 to outer plug element 24, there is a ring-shaped limit stop shoulder 49. Outer plug element 24 also has an inclined outer surface 50, whose diameter increases in the direction of cutting elements 14.

[0055] Groove 33 is arranged on the inner shell surface 47 of outer plug element 24. By the arrangement of groove 33 in outer plug element 24, the spring effect of outer plug element 24 can be increased. Groove 33 is designed in a ring-shaped manner and arranged in a plane perpendicular to axis of rotation 22 of drill bit 10. An annular designed groove, which is arranged in the axial direction at the level of slit-shaped recesses 25, supports the spring effect of the portions of the outer plug element 24 between slit-shaped recesses 25.

[0056] FIG. 4 depicts drill bit 10 according to the invention with cutting portion 11 and drill shaft portion 12, which are connected via the detachable connection, in a longitudinal cross-section along sectional plane C-C in FIG. 1B.

[0057] In a connected state, drill shaft portion 12 abuts limit stop shoulder 49 of cutting portion 11 with end face 29. The length of inner plug element 26 is greater than the length of outer plug element 24, so that an axial gap 51 is formed between end face 48 of outer plug element 24 and limit stop shoulder 32 of inner plug element 26. Due to the length difference between inner plug element 26 and outer plug element 24, one can ensure that end face 29 of inner plug element 26 abuts limit stop shoulder 49 of outer plug element 24 and that a defined force transmission occurs from drill shaft portion 12 to cutting portion 11 when drilling.

[0058] The retention force that tongue 34 and groove 33 withstand can be adjusted via the geometry of tongue 34 and groove 33. The latching-in of tongue 34 and groove 33 is to be as convenient for the operator as possible. An inclined surface simplifies the latching-in. Suited as geometric parameters for adjusting the retention force are, for example, the radial height of tongue 34, i.e., the height in a radial direction, the contact surface between tongue 34 and the inner plug element, and the inclination angle.

[0059] The axial height of groove 33, i.e., the height of groove 33 in an axial direction, is at least 1 mm greater than the axial height of tongue 34. The difference between the axial heights of groove 33 and tongue 34 is selected to be larger than would be necessary for tolerance reasons. The difference of the axial heights can be used to shift drill bit portions 11, 12 in relation to each other to disengage the form-fitting connection so that the operator can enlarge axial gap 51 and apply a tool in axial gap 51.