Drill bit with an exchangeable cutting portion

Abstract

A drill bit, which is rotatable in a direction of rotation about an axis of rotation, is disclosed. The drill bit has a cutting portion with an annular portion where the annular portion has a first end on which is a cutting element and has at a second end a first insertion element. The drill bit has a drill shaft portion with a cylindrical drill shaft which has at an end, towards the cutting portion, a second insertion element. In a direction of insertion parallel to the axis of rotation, the insertion elements form a plug-in connection and can be additionally connected by way of at least one pin element which is movable in at least one slit-shaped clearance.

Claims

1. A drill bit that is rotatable in a rotational direction around an axis of rotation, comprising: a cutting portion having an annular portion, a cutting element connected on a first end of the annular portion, an outer insertion element connected on a second end of the annular portion, and an annular limit stop shoulder disposed at a transition from the annular portion to the outer insertion element; and a drill shaft portion having a cylindrical drill shaft and an inner insertion element, wherein the inner insertion element is connected to the cylindrical drill shaft at a first end and has an abutting face at a second end; wherein in a connected state the abutting face of the inner insertion element is in flush contact with the annular limit stop shoulder of the cutting portion, wherein the outer insertion element and the inner insertion element together form a plug connection in an insertion direction that is parallel to the axis of rotation and wherein the outer insertion element and the inner insertion element are connectable to each other via a pin element that is attached to an outside of the inner insertion element and is movable into a slit-shaped clearance in the outer insertion element; wherein the slit-shaped clearance includes a connector slit and a transverse slit having a catching region and a locking region, wherein the catching region is disposed on a first side of the connector slit and the locking region is disposed on a second side of the connector slit; and wherein a nose is disposed on the outside of the inner insertion element, wherein the outer insertion element includes a groove, and wherein the nose and the groove form a positive connection in an axial direction in the connected state.

2. The drill bit according to claim 1, wherein a height of the connector slit parallel to the axis of rotation is at least 10 mm.

3. The drill bit according to claim 2, wherein the height of the connector slit parallel to the axis of rotation does not exceed 13 mm.

4. The drill bit according to claim 1, wherein the transverse slit has a distance parallel to the axis of rotation from a lower edge of the annular portion of at least 3 mm.

5. The drill bit according to claim 4, wherein the distance parallel to the axis of rotation from the lower edge of the annular portion does not exceed 5 mm.

6. The drill bit according to claim 1, wherein the pin element has a pin height perpendicular to the axis of rotation that is 68% to 89% of a width of the drill shaft.

7. The drill bit according to claim 1, wherein the pin element is cylindrical with a pin radius that is between 2.5 and 5 mm.

8. The drill bit according to claim 7, wherein a width of the catching region is not less than the pin radius plus 1.5 mm.

9. The drill bit according to claim 8, wherein the width of the catching region does not exceed the pin radius plus 3 mm.

10. The drill bit according to claim 8, wherein the width of the catching region is greater than a width of the locking region.

11. The drill bit according to claim 8, wherein the width of the catching region and a width of the locking region are equal.

12. The drill bit according to claim 1, wherein a length of the inner insertion element is greater than a length of the outer insertion element.

13. The drill bit according to claim 12, wherein the length of the outer insertion element is at least 18 mm.

14. The drill bit according to claim 13, wherein the length of the outer insertion element does not exceed 28 mm.

15. The drill bit according to claim 1, wherein the outer insertion element and the inner insertion element are annular with a difference between an inner diameter of the outer insertion element and an outer diameter of the inner insertion element being greater than 0.11 mm.

16. The drill bit according to claim 15, further comprising one or more additional pin elements that are attached to the outside of the inner insertion element and further comprising one or more additional slit-shaped clearances, wherein a number of the slit-shaped clearances is greater than or equal to a number of the pin elements.

17. The drill bit according to claim 1, wherein the annular portion includes a guide portion, wherein the guide portion rests flush against an outer edge, an inner edge, or against the outer edge and the inner edge of the cutting element parallel to the longitudinal axis.

18. The drill bit according to claim 17, wherein a length of the guide portion parallel to the axis of rotation is less than 4 mm.

19. The drill bit according to claim 1, wherein the nose is disposed in the axial direction between the pin element and the drill shaft and wherein the groove is disposed in the axial direction at a level of the slit-shaped clearance.

20. The drill bit according to claim 1, wherein the groove is annular and is disposed in a plane perpendicular to the axis of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A, B illustrate the drill bit according to the invention having a cutting portion and a drill shaft portion in its non-connected state (FIG. 1A) and in its connected state (FIG. 1B);

(2) FIGS. 2A, B illustrate the drill shaft portion of the drill bit shown in FIG. 1 in a longitudinal section along the section plane A-A in FIG. 1A (FIG. 2A) and the insertion element of the drill shaft portion in an enlarged view (FIG. 2B);

(3) FIGS. 3A, B illustrate the cutting portion of the drill bit shown in FIG. 1 in a longitudinal view (FIG. 3A) and the insertion element of the cutting portion in an enlarged view (FIG. 3B);

(4) FIGS. 4A, B illustrate the cutting portion in a longitudinal section along the section plane B-B in FIG. 1A (FIG. 4A) and along the section plane C-C in FIG. 1B (FIG. 4B); and

(5) FIG. 5 illustrates an additional embodiment of a drill bit according to the invention having a cutting portion and a drill shaft portion that are connected in the axial direction via an additional positive connection as removal prevention.

DETAILED DESCRIPTION OF THE DRAWINGS

(6) FIGS. 1A, B show a drill bit 10 according to the invention having a cutting portion 11 that is connected via a removable plug-and-twist connection to a drill shaft portion 12. FIG. 1A shows the cutting portion 11 and the drill shaft portion 12 in their non-connected state with the plug-and-twist connection open and FIG. 1B shows the cutting portion 11 in the drill shaft portion 12 in their connected state with the plug-and-twist connection closed.

(7) The cutting portion 11 comprises an annular portion 13 that is connected on a first end to a plurality of cutting elements 14 and, on a second end, comprises a first insertion element 15. Here, the first insertion element is designed as an outer insertion element 15. The cutting elements 14 are welded, soldered, bolted, or attached in some other suitable manner to the annular portion 13. The cutting portion 11 may, instead of a plurality of cutting elements 14, also comprise a single cutting element embodied as a cutting sleeve, which is connected to the annular portion 13.

(8) The drill shaft portion 12 comprises a cylindrical drill shaft 16 that comprises a second insertion element 17 on an end facing the cutting portion 11 and, on an end opposite the cutting portion 11, is connected to a receiving portion 18. Here, the second insertion element is embodied as an inner insertion element 17. The receiving portion 18 comprises a cover 19 and an insertion end 20. The drill bit 10 is fastened in the tool receptacle of a core drilling device via the insertion end 20. During drilling operation, the drill bit 10 is driven by the core drilling device in a rotational direction 21 around an axis of rotation 22 and in a drilling direction 23 parallel to the axis of rotation 22 in the substrate to be drilled. The axis of rotation 22 runs coaxially to a longitudinal axis of the drill shaft 16 and a longitudinal axis of the annular portion 13. The drill bit 10 has a circular cross-section perpendicular to the axis of rotation 22; alternately, drill bits according to the invention may also have other suitable cross-sections such as, for example, a polygonal cross-section.

(9) The cutting portion 11 is connected to the drill shaft portion 12 via a plug-and-twist connection 24 (FIG. 1B). The term plug-and-twist connection is used to describe connections of two connector elements that form a plug connection in at least one direction, with the inserted connector elements additionally being connected via a twist connection. Here, the plug connection and the twist connection may be closed one after the other or simultaneously. The plug-and-twist connection 24 must connect the cutting portion 11 and the drill shaft portion 12 in all translational and rotational directions. The cutting portion 11 must be secured against translations in the drilling direction 23, opposite the drilling direction 23, and radially in the drilling direction 23 as well as against rotations around the axis of rotation 22.

(10) The cutting portion 11 is connected by placing the outer insertion element 15 over the inner insertion element 17 of the drill shaft portion 12, with the insertion direction of the plug connection running parallel to the axis of rotation 22. The plug connection of the insertion elements 15, 17 secures the cutting portion against translations opposite the drilling direction 23 and radially to the axis of rotation 22. Via the twist connection of the insertion elements 15, 17, the cutting portion 11 must be secured against a rotation around the axis of rotation 22 and against a translation in the drill direction 23. The twist connection comprises six pin elements 25 that are inserted into six slit-shaped clearances 26. The six pin elements 25 are attached on the outer side 27 of the inner insertion element 17 and the six slit-shaped clearances 26 are provided on the outer insertion element 15. The pin elements 25 and the clearances 26 are distributed in an even fashion around the axis of rotation 22. Due to the even distribution, the assignment of an element 25 to a clearance 26 is unnecessary, and a pin element 25 may be inserted into any clearance 26.

(11) The cutting portion 11 may be attached by the operator to the drill shaft portion 12 in a simple and quick manner. To this end, the cutting portion 11 with its outer insertion element 15 is connected by insertion to the inner insertion element 17 of the drill shaft portion 12 in such a way that the pin elements 25 are disposed in the slit-shaped clearances 26. The cutting portion 11 is moved in the insertion direction and subsequently secured by a rotation around the axis of rotation 22.

(12) FIGS. 2A, B show the drill shaft portion 12 of the drill bit 10 according to the invention in the longitudinal section along a sectional plane A-A in FIG. 1A. FIG. 2A shows the drill shaft portion 12 and FIG. 2B shows the second insertion element 17 embodied as an inner insertion element in an enlarged view.

(13) The drill shaft portion 12 comprises the cylindrical drill shaft 16 and the inner insertion element 17, which is designed monolithically. As an alternative to a monolithic design, the inner insertion element 17 may be embodied as a separate part and be subsequently connected to the drill shaft 16. On the outer side 27 of the inner insertion element 17, the pin elements 25 are fastened. The pin elements 25 and the inner insertion element 17 may be made of different materials and connected to one another or they may be made of the same material and the pin elements 25 may be generated using deformation methods such as punching or penetration.

(14) The drill shaft 16 has an outer diameter d.sub.a, perpendicular to the axis of rotation 22, an inner diameter d.sub.i, and a drill shaft width b, b=(d.sub.Ad.sub.i)/2. The inner insertion element 17 has an outer diameter d.sub.2,a perpendicular to the axis of rotation 22 and an inner diameter d.sub.2,i. Here, the inner diameter d.sub.2,i of the inner insertion element 17 corresponds to the inner diameter d.sub.i of the drill shaft 16 and the outer diameter d.sub.2,a of the inner insertion element 17 is less than the outer diameter d.sub.a of the drill shaft 16, such that an annular step forms on the outside of the drill shaft portion 12.

(15) FIG. 2B shows the inner insertion element 17 in an expanded view. The inner insertion element 17 comprises an exterior jacket surface 31, an interior jacket surface 32, and a face 33. An annular limit stop shoulder 34 is located at the transition from the drill shaft 16 to the inner insertion element 17.

(16) The inner insertion element 17 has a length 12 parallel to the axis of rotation 22 and a width b.sub.2 perpendicular to the axis of rotation 22. The pin element 25 has a cylindrical design with a pin radius R.sub.Z parallel to the axis of rotation 22 and a pin height H.sub.Z perpendicular to the axis of rotation 22. The lower edge of the pin element 25 is located parallel to the axis of rotation 22 at a distance A.sub.Z from the face 33 of the inner insertion element 17.

(17) FIGS. 3A, B show the cutting portion 11 of the drill bit 10 shown in FIG. 1 in the longitudinal section parallel to the plane of projection of FIG. 1A. Here, FIG. 3A shows the entire cutting portion 11 and FIG. 3B shows a slit-shaped clearance 26 in the outer insertion element 15 in an enlarged view.

(18) The cutting portion 11 comprises the annular portion 13, the cutting elements 14, and the outer insertion element 15. The annular portion 13 and the outer insertion element 15 are designed in a monolithic fashion in the embodiment shown here. As an alternative to a monolithic design, the outer insertion element 15 may also be designed as a separate part and be connected subsequently to the annular portion 13.

(19) The cutting elements 14 are disposed in one plane perpendicular to the axis of rotation 22 in a ring shape around the annular portion 13 and each comprise an outer edge 41 and an inner edge 42. The outer edges 41 of the cutting elements 14 form an outer circle with an outer diameter D.sub.a and the inner edges form an inner circle having an inner diameter D.sub.i. The cutting elements 14 produce a drill bore in the substrate with a drill bore diameter corresponding to the outer diameter D.sub.a. In the interior of the drill bit 10, a drill core results having a drill core diameter corresponding to the inner diameter D.sub.i. The outer insertion element 15 has an outer diameter d.sub.1,a and an inner diameter d.sub.1,i perpendicular to the axis of rotation 22. Here, the outer diameter d.sub.1,a of the outer plug element 15 is smaller than the outer diameter D.sub.a and the inner diameter d.sub.1,i of the outer insertion element 15 is greater than the inner diameter D.sub.i.

(20) FIG. 3B shows a slit-shaped clearance 26 in the outer insertion element 15 in an enlarged view. The slit-shaped clearance 26 comprises a transverse slit 43 disposed perpendicular to the axis of rotation 22 and a connector slit 44 disposed parallel to the axis of rotation 22. The connector slit 44 connects the transverse slit 43 to an upper edge 45 of the outer insertion element 15, which is designed in an open fashion on the upper edge 45 in the region of the connector slit 44. The pin elements 25 are inserted via the connector slit 44 into the slit-shaped clearance 26 and displaced into the transverse slit 43 by a rotation around the axis of rotation 22. The transmission of torque from the pin element 25 onto the outer connector element 15 occurs in the transverse slit 43.

(21) The outer insertion element 15 has a length 11 parallel to the axis of rotation 22 and a width b.sub.1 perpendicular to the axis of rotation 22 (FIG. 4A). The transverse slit 43 has a width B perpendicular to the axis of rotation 22 and a height H parallel to the axis of rotation 22. The connector slit 44 has a width b perpendicular to the axis of rotation 22 and a height h parallel to the axis of rotation 22. The width of the connector slit 44 is greater than the pin diameter 2R.sub.Z of the pin elements 25, such that the pin elements 25 can be easily inserted into the connector slit 44. Here, the insertion of the pin elements 25 can be facilitated using an inclined insertion surface 46 on the upper edge 45. The height h of the connector slit 44 is selected such that the cutting portion 11 is sufficiently able to withstand tensile forces during the release of a jammed drill bit. If the height h is selected to be too low, the risk is incurred of deforming the outer insertion element 15.

(22) The transverse slit 43 has a lower distance A.sub.1,u from the annular portion 13 parallel to the axis of rotation 22 and an upper distance from the upper edge 45, with the upper distance corresponding to the height h of the connector slit 44. The lower distance A.sub.1,u from the annular portion 13 is selected in such a way that the cutting portion 11 is sufficiently able to withstand tensile force exerted by a drill stand. If the lower distance A.sub.1,u is selected to be too small, the risk is incurred of a deformation of the outer insertion element 15.

(23) The transverse slit 43 comprises a catching region 47, a locking region 48, and a transitional region 49. The catching region 47 and the locking region 48 are disposed on different sides of the connector slit 44 relative to the rotational direction 21 of the drill bit 10, with the catching region and locking region 47, 48 being connected to the connector slit 44 via the transitional region 49. The catching area 47 is disposed on the side of the connector slit 44 facing the rotational direction 21 and the locking region 48 is disposed on the side opposite the rotational direction 21. The transmission of torque from the drill shaft portion 12 onto the cutting portion 11 occurs via the pin elements 25 and the catching region 47. The locking region 48 reduces the risk of the plug-and-twist connection 24 between the drill shaft portion 12 and the cutting portion 11 being unintentionally opened during the removal of a jammed drill bit from the substrate.

(24) The catching region 47 has a width B.sub.1 perpendicular to the axis of rotation 22 and the height of the catching region 47 corresponds to the height H of the transverse slit 43. The locking region 48 has a width B.sub.2 perpendicular to the axis of rotation 22 and the height of the locking region 48 corresponds to the height H of the transverse slit 43. The widths B.sub.1, B.sub.2 of the catching region 47 and the locking region 48 are selected in such a way that the pin elements 25 can be held in the transverse slit 43 in the case of the exertion of tensile force and do not break out.

(25) FIGS. 4A, B show the cutting portion 11 of the drill bit 10 according to the invention in a longitudinal section along the section plane B-B in FIG. 1A (FIG. 4A) and along the section plane C-C in FIG. 1B (FIG. 4B). The cutting portion 11 comprises the annular portion 13, the cutting elements 14, and the outer insertion element 15.

(26) The cutting elements 14 are comprised of a matrix zone 51 and a neutral zone 52, with the matrix zone 51 being composed of a powder material to which cutting particles have been added and the neutral zone 52 being composed of a weldable powder material without cutting particles. The two-part structure of the cutting elements 14 is necessary in order to be able to weld the cutting elements 14 to the annular portion 13. The annular portion 13 rests flush against the inner edge 42 of the cutting element 14 and has a rebound 53 relative to the outer edge 41 of the cutting element 14.

(27) The annular portion 13 comprises a guide portion 54 and a core removal portion 55 on its inner side. The core removal portion 55 has an inner diameter that reduces in the direction of the cutting elements 14; the oblique surface of the core removal portion 55 supports the removal of the drill core. The guide portion 54 rests flush against the cutting element 14 and, during drilling, forms a guide for the cutting elements 14; the guide portion 54 has a length m parallel to the axis of rotation 22. As an alternative to the guide on the inside of the drill bit 10, the guide portion may be disposed on the outside or on the outside and inside. The length m of the guide portion 54 is less than 4 mm. A guide portion that is less than 4 mm does not interfere with the supply of a cooling and rinsing medium, or at least does not do so to a substantial degree.

(28) The outer insertion element 15 comprises an outer jacket surface 56, an inner jacket surface 57, and a face 58. An annular limit stop shoulder 59 is located at the transition from the annular portion 13 to the outer insertion element 15. In the cutting portion 11 shown in FIG. 4A, the outer insertion element 15 additionally comprises an oblique outer surface 60 whose diameter increases in the direction of the cutting elements 14.

(29) FIG. 4B shows the cutting portion 11 and the drill shaft portion 12 that are connected via the plug-and-twist connection 24, with the pin element 25 being disposed in the locking region 48 of the transfer slit 43. In the connected state, the drill shaft portion 12 rests with its face 33 against the limit stop shoulder 59 of the cutting portion 11. Between the inner jacket surface 57 of the outer insertion element 15 and the outer jacket surface 31 of the inner insertion element 17, there is a radial gap 61. Here, the difference .sub.radial between the inner diameter d.sub.1,i of the outer insertion element 15 and the outer diameter d.sub.2,a of the inner insertion element 17 is greater than 0.11 mm for all diameters. The length l.sub.2 of the inner insertion element 17 is greater than the length 11 of the outer insertion element 15, such that an axial gap 62 having the gap width .sub.axial and is formed between the face 58 of the outer insertion element 15 and the limit stop shoulder 34 of the inner insertion element 17. The radial gap 61 and the axial gap 62 to ensure that the face 33 of the inner insertion element 17 rests against the limit stop shoulder 59 of the outer insertion element 15 and, during drilling, a defined transmission of force occurs from the drill shaft portion onto the cutting portion.

(30) FIG. 5 shows an additional embodiment of a drill bit 70 according to the invention having a cutting portion 71 and a drill shaft portion 72. The drill bit 70 differs from the drill bit 10 in that, in the axial direction, an additional positive connection is provided that impedes an unintentional release of the cutting portion 71 from the drill shaft portion 72.

(31) In addition to the outer insertion element 15 and the slit-shaped clearances 26, the cutting portion 71 comprises a first connector unit 73 and the drill shaft portion 72, in addition to the inner insertion element 17 and the pin elements 25, comprises a second connector unit 74. The first connector unit 73 comprises a groove 75 disposed on the inside 57 of the outer connector element 15. The second connector unit 74 comprises a nose 76 that is disposed on the outside 28 of the inner insertion element 17 and that extends radially outward. In the connected state of the drill bit 70, the nose 76 and the groove 75 form a positive connection in the axial direction, i.e., in the drill direction 23, between the cutting portion 71 and the drill shaft portion 72. The cutting portion 71 is secured by means of the nose 76 and the groove 75 against the drill shaft portion 72 being pulled off of the cutting portion 71.

(32) The nose 76 is disposed in the axial direction between the pin elements 25 and the drill shaft 16. In order to remove the drill shaft portion 72 from the cutting portion 71, a force is exerted on the face of the outer insertion element 15 with the aid of a tool. By the effect of the force, the elastic portion of the outer insertion element 15 is deflected and the positive connection between the nose 76 and the groove 75 can be released. The greater the distance of the nose 76 from the face 33 of the inner insertion element 17, the greater the deflection of the elastic portion. The groove 75 has an annular design and is disposed in a plane perpendicular to the axis of rotation 22. An annular groove that is disposed in the axial direction at the height of the slit-shaped clearances 26 supports the elastic effect of the portions of the outer insertion element 15 between the slit-shaped clearances 26.

(33) The retaining force withstood by the nose 76 and the groove 75 can be adapted using the geometry of the nose 76 and the groove 75. Locking the nose 76 into the groove 75 should be as comfortable as possible for the operator; an oblique surface facilitates locking in. The radial height of the nose 76, i.e., its height in the radial direction, the contact surface between the nose 76 and the inner insertion element 17, and the angle of incline, for example, are suitable as geometric parameters for the adjustment of the retaining force.