Drill Bit Having a Spiral-Tube-Shaped Drill Shaft and Method for Producing a Spiral-Tube-Shaped Drill Shaft for a Drill Bit

Abstract

A drill bit for creating a borehole includes a drill shaft portion which has a tubular drill shaft, a receiving portion which has a cover and an insertion end, and a connecting device which connects the drill shaft portion and the receiving portion together releasably or non-releasably. The tubular drill shaft is configured as a welded spiral tube.

Claims

1.-16. (canceled)

17. A drill bit for creating a borehole having a borehole diameter and having a drilled core having a core diameter in a workpiece, comprising: a drill shaft portion with a tubular drill shaft; a receiving portion which has a cover and an insertion end; and a connecting device which connects the drill shaft portion and the receiving portion together releasably or non-releasably; wherein the tubular drill shaft is configured as a welded spiral tube.

18. The drill bit according to claim 17, wherein the tubular drill shaft is formed from N, wherein N>1, strip materials and wherein respective strip edges of the strip materials are integrally joined by N, wherein N>1, spiral-shaped connection welds.

19. The drill bit according to claim 18, wherein the strip materials are configured as flat sheets having a constant sheet thickness.

20. The drill bit according to claim 18, wherein the strip materials are configured as flat sheets having at least one recess.

21. The drill bit according to claim 18, wherein the strip materials are configured as profiled sheets with a profiled cross-section and wherein the profiled sheets have a sheet thickness and a profiled height.

22. The drill bit according to claim 18, wherein at least one of the spiral-shaped connection welds protrudes relative to the strip materials and wherein the at least one of the spiral-shaped connection welds contains a seam material.

23. The drill bit according to claim 22, wherein the seam material and the strip materials have same material properties.

24. The drill bit according to claim 22, wherein the seam material and the strip materials have different material properties.

25. The drill bit according to claim 24, wherein the seam material has a higher tensile strength and/or a higher wear resistance than the strip materials.

26. The drill bit according to claim 22, wherein the at least one of the spiral-shaped connection welds protrudes on an inside of the tubular drill shaft with an inner protrusion relative to the strip materials.

27. The drill bit according to claim 22, wherein the at least one of the spiral-shaped connection welds protrudes on an outside of the tubular drill shaft with an outer protrusion relative to the strip materials.

28. The drill bit according to claim 22, wherein the at least one of the spiral-shaped connection welds protrudes on an inside of the tubular drill shaft with an inner protrusion relative to the strip materials and on an outside of the tubular drill shaft with an outer protrusion relative to the strip materials.

29. A method for producing the tubular drill shaft for the drill bit according to claim 17, wherein N, wherein N1, strip materials are shaped into a spiral tube and are integrally joined at respective abutting strip edges by N, wherein N1, spiral-shaped connection welds.

30. The method according to claim 29, wherein a seam material is used when integrally joining the respective abutting strip edges.

31. The method according to claim 30, wherein the seam material has a higher tensile strength and/or a higher wear resistance than the strip materials.

32. The method according to claim 29, wherein when integrally joining the respective abutting strip edges a first seam material and a second seam material are used, wherein material properties of the first seam material are different from material properties of the second seam material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIGS. 1A, B show a first embodiment of an inventive drill bit with a spiral-shaped shaft, the drill bit being connectable to a separate cutting portion;

[0029] FIGS. 2A, B show a longitudinal section through the drill bit of FIG. 1 along the cutting line A-A in FIG. 1B (FIG. 2A) and a detail of the drill shaft of FIG. 2A in an enlarged view (FIG. 2B);

[0030] FIG. 3 shows a second embodiment of an inventive drill bit with a spiral-tube-shaped drill shaft, which is connected to several cutting segments and has three recesses on the inside;

[0031] FIGS. 4A, B show a longitudinal section through the drill bit of FIG. 3 along the cutting line A-A in FIG. 3 (FIG. 4A) as well as a detail of the drill shaft of FIG. 4A in an enlarged representation (FIG. 4B);

[0032] FIG. 5 shows a third embodiment of an inventive drill bit with a spiral-tube-shaped drill shaft connected to several cutting segments and made of a profiled sheet; and

[0033] FIGS. 6A, B show a longitudinal section through the drill bit of FIG. 5 along the cutting line A-A in FIG. 5 (FIG. 6A) as well as a detail of the drill shaft of FIG. 6A in an enlarged representation (FIG. 6B).

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] FIGS. 1A, B show a first embodiment of an inventive drill bit 10, hereinafter referred to as the first drill bit 10. The first drill bit 10 comprises a drill shaft portion 11, a receiving portion 12 and a connecting device 13 which permanently connects the drill shaft portion 11 to the receiving portion 12. The first drill bit 10 can be connected to a separate cutting portion 14 via another detachable connecting device 15. FIG. 1A shows the first drill bit 10 and the cutting portion 14 in the unconnected state and FIG. 1B the first drill bit 10 and the cutting portion 14 in the connected state.

[0035] The cutting portion 11 comprises a ring portion 16 and several cutting segments 17 connected to the ring portion 16. The cutting segments 17 are arranged in a ring shape and form a cutting ring with intermediate spaces. The cutting portion 14 can also have a single cutting segment designed as a closed cutting ring instead of several cutting segments 17. The cutting segments 17 are welded, soldered, glued or fastened in another suitable way to the ring portion 16. The drill shaft portion 11 comprises a spiral-tube-shaped drill shaft 18 and the receiving portion 12 comprises a cover 19 and an insertion end 20 over which the first drill bit 10 is fastened in a tool holder of a core drill. In drilling operation, the first drill bit 10 is driven by the core drill about a drilling axis 21 and moved in a drilling direction 22 parallel to the drilling axis 21 into a workpiece 23 to be machined. The first drill bit 10 produces a drilled core 24 with a core diameter d.sub.1 and a borehole 25 with a borehole diameter d.sub.2 in the workpiece 23.

[0036] The drill shaft 18 is designed as a welded spiral tube, which was manufactured from a strip material 31 in the form of a flat sheet by forming and welding. The flat strip material 31 was formed into a spiral tube and joined at the abutting strip edges by means of a spiral-shaped connection weld 32. The spiral-shaped connection weld 32 acts as a stiffening element for the drill shaft 18 and increases the stiffness of the drill shaft 18 compared to a longitudinally welded or tubular drill shaft of the same wall thickness.

[0037] FIGS. 2A, B show a longitudinal section through the first drill bit 10 of FIG. 1 along the cutting line A-A in FIG. 1B (FIG. 2A) and a detail of the drill shaft 16 of FIG. 2A in a magnified view (FIG. 2B).

[0038] The spiral-shaped connection weld 32 protrudes from the formed strip material 31 on an outside 33 and an inside 34 of the drill shaft 16. The protrusion of the spiral-shaped connection weld 32 on the outside 33 of the drill shaft 16 is called the outer protrusion .sub.A and the protrusion of the spiral-shaped connection weld 32 on the inside 34 of the drill shaft 16 is called the inner protrusion .sub.I. In order to produce the spiral-shaped connection weld 32 protruding from the formed strip material 31 on the outside and inside 33, 34, a seam material 35 is used for welding the formed strip material 31, which provides the required material volume. The seam material 35 can be powder-shaped, wire-shaped or tape-shaped. Furthermore, the material properties of the seam material 35 can be adapted to the desired properties of the spiral-shaped connection weld 32.

[0039] The spiral-shaped connection weld 32 improves the guidance of the drill shaft 18 when drilling with the first drill bit 10. The smaller the gap between the spiral-shaped connection weld 32 and the borehole 25 on the outside 33 or between the spiral-shaped connection weld 32 and the drilled core 23 on the inside 34, the better the guidance of the drill shaft 18. The spiral-shaped connection weld 32 can be removed through friction between the spiral-shaped connection weld 32 and the borehole 25 on the outside 33 or between the spiral-shaped connection weld 32 and the drilled core 24 on the inside 34, whereby the guidance of the drill shaft 18 deteriorates. By using seam material 35, which has a higher tensile strength and wear resistance than the strip material 31, the properties of the spiral-shaped connection weld 32 can be influenced, so that guidance of the drill shaft 18 over the spiral-shaped connection weld 32 is ensured as far as possible during the entire service life of the drill shaft 18.

[0040] FIG. 3 shows a second embodiment of an inventive drill bit 40, hereinafter referred to as the second drill bit 40. The second drill bit 40 comprises a drill shaft portion 41, a receiving portion 42, and a connecting device 43, which permanently connects the drill shaft portion 41 to the receiving portion 42.

[0041] Drill shaft portion 41 includes a spiral-tube-shaped drill shaft 44 and multiple cutting segments 45 that are welded, soldered, bonded or fastened to the drill shaft 44 in any other suitable manner. The receiving portion 42 comprises a cover 46 and an insertion end 47, through which the third drill bit 40 is fastened in a tool holder of a core drill. In drilling operation, the second bit 40 is driven by the core drill about a drilling axis 48 and moved in a drilling direction 49 parallel to the drilling axis 48 into the workpiece 23 to be machined.

[0042] The second drill bit 40 has several cutting segments 45, which are permanently attached to the drill shaft 44. The second drill bit 40 can also have a single cutting segment designed as a closed cutting ring instead of several cutting segments 45. The cutting segments 45 are welded, soldered, glued or fastened in another suitable way to the drill shaft 44.

[0043] The drill shaft 44 is designed as a spiral tube in the form of a welded spiral tube, which was manufactured from a strip material 51 in the form of a flat sheet with recesses by forming and welding. The strip material 51 was formed into a spiral tube and joined at the abutting strip edges by means of a spiral-shaped connection weld 52.

[0044] FIGS. 4A, B show a long section through the second drill bit 40 of FIG. 3 along the intersection line A-A in FIG. 3 (FIG. 4A) and a detail of the drill shaft 46 of FIG. 4A in an enlarged representation (FIG. 4B).

[0045] The spiral-shaped connection weld 52 of the drill shaft 44 protrudes from an outside 53 of the drill shaft 44 with an outer protrusion .sub.A in relation to the formed strip material 51 and is substantially flush with the formed strip material 51 on an inside 54 of the drill shaft 44. In order to produce the spiral-shaped weld 52 protruding from the outside 53, a seam 55 is used when welding the formed strip material 51, which provides the required material volume.

[0046] The seam material 55 can be shaped as powder, wire or tape. The properties of the spiral-shaped connection weld 52 can be adapted via the material properties of the seam material 55. The seam material 55 can have the same material properties or different material properties as the strip material 51. If the seam material 55 and the strip material 51 have the same material properties, the weld of the tape edges results in a uniform transition and the seam material 55 can bond well with the strip material 51. By using a seam material 55, which has a higher tensile strength and/or wear resistance than the strip material 51, the properties of the spiral-shaped connection weld 52 can be influenced, so that guidance of the drill shaft 44 over the spiral-shaped connection weld 52 is ensured as far as possible during the entire service life of the drill shaft 46.

[0047] The second drill bit 40 shows a spiral-tube-shaped drill shaft 44 with a spiral-shaped connection weld 52, which protrudes on the outside 53 of the drill shaft 44 from the formed strip material 51 and is formed substantially flush with the formed strip material 51 on the inside 54 of the drill shaft 44. Alternatively, the spiral-shaped connection weld 52 on the inside 54 of the drill shaft 44 can protrude with an inner protrusion .sub.I in relation to the formed strip material 51 and be substantially flush with the formed strip material 51 on the outside 53 of the drill shaft 46. A spiral-shaped connection weld 52 protruding from the inside 54 of the drill shaft 44 allows the drill shaft 44 to be guided over the drilled core 24 when drilling with the second drill bit 40. In addition, the spiral-shaped connection weld 52 protruding from the inside 54 can support the supply of clean cooling and flushing fluid during wet drilling. The spiral-shaped connection weld 52 acts as a conveying spiral for the clean cooling and flushing fluid when the direction of rotation of the second drill bit 40 and the direction of the spiral-shaped connection weld 52 on the inside 54 of the drill shaft 44 coincide.

[0048] Wet drilling with the second drill bit 40 requires a cooling and flushing fluid, which cools the cutting segments 45 as cooling fluid and removes cuttings from the borehole 25 as flushing fluid. The spiral-shaped connection weld 52 protruding from the outside 53 of the drill shaft 44 can support the removal of used cooling and flushing fluid mixed with cuttings, in addition to guiding the drill shaft 44 through the borehole 25. The spiral-shaped connection weld 52 acts as a conveying spiral for the used cooling and flushing fluid mixed with cuttings, when the direction of rotation of the second drill bit 40 and the direction of the spiral-shaped connection weld 52 on the outside 53 of the drill shaft 44 coincide.

[0049] Three recesses 56A, 56B, 56C, known as the first recess 56A, the second recess 56B and the third recess 56C, are located on the inside 54 of the drill shaft 44 to provide clean cooling and flushing fluid to the inside 54 of the drill shaft 44. The recesses 56A, 56B, 56C are created in the sheet prior to forming the strip material 51 into a spiral tube and serve as a transport channel for the necessary cooling and flushing fluid when wet drilling with the second bit 40. The recesses 56A, 56B, 56C are necessary especially in case of a small internal gap between the drilled core and the drill shaft. The number of recesses 56A, 56B, 56C, the geometry of the recesses 56A, 56B, 56C and the arrangement of the recesses 56A, 56B, 56C on the outside 53 and/or inside 54 of the drill shaft 44 can be adapted to the amount of fluid in the cooling and flushing fluid.

[0050] The recesses 56A, 56B, 56C provided on the inside 54 of the drill shaft 44 are for the supply of clean cooling and flushing fluid and the recesses provided on the outside 53 of the drill shaft 44 can support the removal of used cooling and flushing fluid mixed with cuttings. Since the recesses 56A, 56B, 56C are made on the second drill bit 40 before the strip material 51 is formed, recesses can be created on the inside 54 of the drill shaft 44 with little manufacturing effort.

[0051] FIG. 5 shows a third embodiment of an inventive drill bit 60, hereinafter referred to as the third drill bit 60. The third drill bit 60 comprises a drill shaft portion 61, a receiving portion 62 and a connecting device 63, which connects the drill shaft portion 61 permanently with the receiving portion 62.

[0052] Drill shaft portion 61 includes a spiral-tube-shaped drill shaft 64 and multiple cutting segments 65 welded, soldered, bonded or otherwise fastened to the drill shaft 64 in another suitable manner. The receiving portion 62 includes a cover 66 and an insertion end 67, over which the third drill bit 60 is fastened in a tool holder of a core drill. In drilling operation, the third drill bit 60 is driven by the core drill about a drilling axis 68 and moved in a drilling direction 69 parallel to the drilling axis 68 into the workpiece 23 to be machined.

[0053] The third drill bit 60 has several cutting segments 65, which are attached to the drill shaft 64 in a permanent manner. The third drill bit 60 can also have a single cutting segment designed as a closed cutting ring instead of several cutting segments 65. The cutting segments 65 are welded, soldered, glued or fastened in another suitable way to the drill shaft 64.

[0054] The drill shaft 64 is designed as a welded spiral tube, which was manufactured from a strip material 71 in the form of a wave-shaped profiled sheet by forming and welding. The strip material 71 was formed into a spiral tube and joined at the abutting strip edges by means of a spiral-shaped connection weld 72. The spiral-shaped connection weld 72 acts as a stiffening element for the drill shaft 64.

[0055] FIGS. 6A, B show a longitudinal section through the third drill bit 60 of FIG. 5 along the cutting line A-A in FIG. 5 (FIG. 6A) as well as a detail of the drill shaft 64 of FIG. 6A in an enlarged representation (FIG. 6B).

[0056] The spiral-shaped connection weld 72 of the drill shaft 64 is formed on an outside 73 of the drill shaft 64 and on an inside 74 of the drill shaft 64 substantially flush with the formed strip material 71. Due to the profiled cross-section of the strip material 71, 66 recesses are created on the outside 73 and on the inside 74 of the drill shaft, through which cooling and flushing fluid can be transported during wet drilling with the third drill bit 60. The recesses provided on the inside 74 of the drill shaft 64 are for the supply of clean cooling and flushing fluid and the recesses provided on the outside 73 of the drill shaft 64 are for the discharge of used cooling and flushing fluid mixed with cuttings. The geometry of the profiled sheet can be adapted to the amount of fluid required for wet drilling.