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

Abstract

A core bit for producing a borehole in a workpiece includes a cutting portion with one or more cutting segments, a drill shaft portion with a tubular drill shaft, and a connecting device which connects the cutting portion and the drill shaft portion releasably or non-releasably together. The tubular drill shaft is configured as a welded spiral tube.

Claims

1.-16. (canceled)

17. A core bit for producing a borehole having a borehole diameter and a drilled core having a core diameter in a workpiece, comprising: a cutting portion with at least one cutting segment which forms a cutting ring having an inner diameter that corresponds to the core diameter and an outer diameter that corresponds to the borehole diameter; a drill shaft portion with a tubular drill shaft; and a connecting device that connects the cutting portion and the drill-shaft portion together releasably or non-releasably; wherein the tubular drill shaft is configured as a welded spiral tube.

18. The core bit according to claim 17, wherein the tubular drill shaft is shaped 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 core bit according to claim 18, wherein the strip materials are configured as flat sheets having a constant sheet thickness.

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

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

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

25. The core 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 core 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 core 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 core 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 core bit according to claim 17, wherein N, wherein N≥1, strip materials are shaped into a spiral tube and are integrally joined at respective abutting strip edges by N, wherein N≥1, 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

[0026] FIGS. 1A, B show a first embodiment of a core bit according to the invention having a cutting portion and a spiral-tube-shaped drill shaft portion, which can be connected by means of a releasable connecting device, in the connected state (FIG. 1A) and in the non-connected state (FIG. 1B);

[0027] FIGS. 2A, B show a longitudinal section of the drill shaft portion of the first core bit of FIG. 1 along the section line A-A in FIG. 1B (FIG. 2A) as well as a detail of the drill shaft of FIG. 2A in an enlarged view (FIG. 2B);

[0028] FIG. 3 shows a second embodiment of a core bit according to the invention having a cutting portion and a spiral-tube-shaped drill shaft portion, which can be connected by means of a non-releasable connecting device;

[0029] FIGS. 4A, B show a longitudinal section of the second core bit of FIG. 3 along the section line A-A in FIG. 3 (FIG. 4A) as well as a detail of the drill shaft of FIG. 4A in an enlarged view (FIG. 4B);

[0030] FIG. 5 shows a third embodiment of a core bit according to the invention having a cutting portion and a spiral-tube-shaped drill shaft portion; and

[0031] FIGS. 6A, B show a longitudinal section of the third core bit of FIG. 5 along the section line A-A in FIG. 5 (FIG. 6A) as well as a detail of the drill shaft of FIG. 6A in an enlarged view (FIG. 6B).

DETAILED DESCRIPTION OF THE DRAWINGS

[0032] FIGS. 1A, B show a first embodiment of a core bit 10 according to the invention, which is hereinafter referred to as the first core bit 10. The first core bit 10 comprises a cutting portion 11, a drill shaft portion 12, and a connecting device 13 that releasably connects the cutting portion 11 to the drill shaft portion 12. FIG. 1A shows the first core bit 10 in the connected state and FIG. 1B shows the first core bit 10 in the non-connected state.

[0033] The cutting portion 11 comprises a ring portion 14 and a plurality of cutting segments 15 that are connected to the ring portion 14. The cutting segments 15 are arranged in a ring and form a cutting ring with intermediate spaces. Instead of a plurality of cutting segments 15, the cutting portion 11 may also have a single cutting segment configured as a closed cutting ring. The cutting segments 15 are welded, soldered or screwed to the ring portion 14 or fixed to the ring portion 14 by another suitable method of attachment. The drill shaft portion 12 comprises a spiral-tube-shaped drill shaft 16, a cover 17 and an insertion end 18, by means of which insertion end the first core bit 10 is fixed in a tool holder of a core drill. During drilling, the first core bit 10 is driven around a drilling axis 19 by the core drill and moved in a drilling direction 21 parallel to the drilling axis 19 into a workpiece 22 that is to be machined. The first core bit 10 produces a drilled core 23 having a core diameter d.sub.1 and a drilled hole 24 having a drilled-hole diameter d.sub.2 in the workpiece 22. The cutting segments 15 form a cutting ring having an inner diameter that corresponds to the core diameter d.sub.1 and an outer diameter that corresponds to the drilled-hole diameter d.sub.z.

[0034] The connecting device 13 is configured as a releasable connecting device in the form of a combined plug-and-pin connection and comprises a first plug connection element 25 that is connected to the ring portion 14 and a second plug connection element 26 that is connected to the drill shaft 16. The first and second plug connection elements 25, 26 form a plug connection and are additionally secured by means of a pin connection. The pin connection comprises a plurality of pin elements 27 that are inserted into T-shaped slots 28. The pin elements 27 are fixed to an outside of the second plug connection element 26 and the T-shaped slots 28 are provided in the first plug connection element 25. The cutting portion 11 can be easily and quickly connected to the drill shaft portion 12 by the user. To this end, the cutting portion 11 with the first plug connection element 25 is placed on the second plug connection element 26 of the drill shaft portion 12 in such a way that the pin elements 27 are placed in the slots 28. The cutting portion 11 is moved in the drilling direction 21 and then secured by a rotation around the drilling axis 19.

[0035] The drill shaft 16 is configured as a welded spiral tube that has been produced from a strip material 31 in the form of a flat sheet by means of shaping and welding. The flat strip material 31 has been shaped 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 member for the drill shaft 16 and increases the stiffness of the drill shaft 16 compared to a longitudinally seam-welded or tubular drill shaft having the same wall thickness.

[0036] FIGS. 2A, B show a longitudinal section of the drill shaft portion 12 of the first core bit 10 of FIG. 1 along the section line A-A in FIG. 1B (FIG. 2A) as well as a detail of the drill shaft 16 of FIG. 2A in an enlarged view (FIG. 2B).

[0037] The spiral-shaped connection weld 32 protrudes relative to the shaped 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 referred to as outer protrusion Δ.sub.A and the protrusion of the spiral-shaped connection weld 32 on the inside 34 of the drill shaft 16 is referred to as inner protrusion Δ.sub.I.

[0038] In order to be able to produce a spiral-shaped connection weld 32 that protrudes relative to the shaped strip material 31 on the outside 33, the inside 34, or the outside and inside 33, 34, a seam material 35 must be used when welding the shaped strip material 31 that provides the volume of material required. The seam material can be in the form of powder, wire or strips. In addition, 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 16 during drilling with the first core bit 10. The smaller the gap between the spiral-shaped connection weld 32 and the borehole 24 on the outside 33 and/or between the spiral-shaped connection weld 32 and the drilled core 23 on the inside 34, the better the drill shaft 16 is guided. Friction between the spiral-shaped connection weld 32 and the borehole 24 on the outside 33 and/or between the spiral-shaped connection weld 32 and the drilled core 23 on the inside 34 may cause the spiral-shaped connection weld 32 to become worn, whereby the guidance of the drill shaft 16 is impaired. Using seam material that has a higher tensile strength and wear resistance than the strip material 31 enables the properties of the spiral-shaped connection weld 32 to be influenced so that guidance of the drill shaft 16 by the spiral-shaped connection weld 32 is ensured as far as possible throughout the whole lifespan of the drill shaft 16.

[0040] FIG. 3 shows a second embodiment of a core bit 40 according to the invention, which is hereinafter referred to as the second core bit 40. The second core bit 40 comprises a cutting portion 41, a drill shaft portion 42 and a connecting device 43 that non-releasably connects the cutting portion 41 to the drill shaft portion 42.

[0041] The cutting portion 41 comprises a plurality of cutting segments 45 that form a cutting ring having an inner diameter that corresponds to the core diameter d.sub.1 and an outer diameter that corresponds to the drilled-hole diameter d.sub.2. The drill shaft portion 42 comprises a spiral-tube-shaped drill shaft 46, a cover 47 and an insertion end 48, by means of which insertion end the second core bit 40 is fixed in a tool holder of a core drill. The cutting segments 15 are non-releasably connected to the drill shaft 46 by means of the connecting device 43, where the connecting device 43 is configured as a welded joint, soldered joint or bonded joint. In principle, any connecting device that non-releasably connects the cutting segments 15 and the drill shaft 46 is suitable.

[0042] The drill shaft 46 is spirally configured in the form of a welded spiral tube that has been made from a strip material 51 in the form of a flat sheet with recesses by means of shaping and welding. The strip material 51 has been shaped into a spiral tube and joined at the abutting strip edges by means of a spiral-shaped connection weld 52.

[0043] The second core bit 40 shows a cutting portion 41 with a plurality of cutting segments 45, which are non-releasably fixed to the drill shaft 46 by means of the connecting device 43. Instead of a plurality of cutting segments 45, the cutting portion 41 may also have a single cutting segment configured as a closed cutting ring. In addition, the cutting portion 41 may have a ring portion that is arranged between the cutting segments 45 and the drill shaft 46. The cutting segments 45 are welded, soldered or screwed to the ring portion or fixed to the ring portion by another suitable method of attachment, and the ring portion and the drill shaft 46 are releasably or non-releasably connected by means of a connecting device. The ring portion may, like the drill shaft 46, be configured as a spiral-tube shape. In the case of thin strip materials, however, using tubular ring portions with a constant wall thickness is recommended, since a larger contact surface is available for fixing the cutting segments 45.

[0044] FIGS. 4A, B show a longitudinal section of the second core bit 40 of FIG. 3 along the section line A-A in FIG. 3 (FIG. 4A) as well as a detail of the drill shaft 46 of FIG. 4A in an enlarged view (FIG. 4B).

[0045] The spiral-shaped connection weld 52 of the drill shaft 46 protrudes on an outside 53 of the drill shaft 46 with an outer Δ.sub.A relative to the shaped strip material 51 and is configured on an inside 54 of the drill shaft 46 to be substantially flush with the shaped strip material 51. In order to produce the spiral-shaped connection weld 52 protruding on the outside 53, a seam material 55 is used when welding the shaped strip material 51 that provides the volume of material required.

[0046] The seam material 55 can be in the form of powder, wire or strips. The properties of the spiral-shaped connection weld 52 can be adjusted by means of the material properties of the seam material 55. The seam material 55 may have the same material properties as or different material properties from the strip material 51. If seam material 55 and strip material 51 have the same material properties, this results in a smooth transition when welding the strip edges and the seam material 55 can bind well with the strip material 51. Using seam material 55 that has a higher tensile strength and/or wear resistance than the strip material 51 enables the properties of the spiral-shaped connection weld 52 to be influenced so that guidance of the drill shaft 46 by the spiral-shaped connection weld 52 is ensured as far as possible throughout the whole lifespan of the drill shaft 46.

[0047] The second core bit 40 shows a spiral-tube-shaped drill shaft 46 having a spiral-shaped connection weld 52 that protrudes on the outside 53 of the drill shaft 46 relative to the shaped strip material 51 and is configured on the inside 54 of the drill shaft 46 to be substantially flush with the shaped strip material 51. Alternatively, the spiral-shaped connection weld 52 may protrude on the inside 54 of the drill shaft 46 with an inner protrusion Δ.sub.I relative to the shaped strip material 51 and be configured on the outside 53 of the drill shaft 46 to be substantially flush with the shaped strip material 51. A spiral-shaped connection weld 52 protruding on the inside 54 of the drill shaft 46 enables the drill shaft 46 to be guided by the drilled core 23 when drilling with the second core bit 40. In addition, the spiral-shaped connection weld 52 protruding on the inside 54 may facilitate the addition of clean cooling and flushing fluid during wet drilling. The spiral-shaped connection weld 52 acts as a conveyor screw for the clean cooling and flushing fluid if the direction of rotation of the second core bit 40 and the orientation of the spiral-shaped connection weld 52 on the inside 54 of the drill shaft 46 coincide.

[0048] Wet drilling with the second core bit 40 requires a cooling and flushing fluid, which, as a cooling fluid, cools the cutting segments 45 and, as a flushing fluid, removes drilling cuttings from the drilled hole 24. The spiral-shaped connection weld 52 protruding on the outside 53 of the drill shaft 46 may, in addition to guidance of the drill shaft 46 by the drilled hole 24, facilitate the removal of used cooling and flushing fluid mixed with drilling cuttings. The spiral-shaped connection weld 52 acts as a conveyor screw for the used cooling and flushing fluid mixed with drilling cuttings if the direction of rotation of the second core bit 40 and the orientation of the spiral-shaped connection weld 52 on the outside 53 of the drill shaft 46 coincide.

[0049] For the purposes of adding clean cooling and flushing fluid to the inside 54 of the drill shaft 46, three recesses 56A, 56B and 56C are arranged on the inside 54 of the drill shaft 46, which are referred to as the first recess 56A, the second recess 56B and the third recess 56C. The recesses 56A, 56B and 56C are produced in the sheet before the shaping of the strip material 51 into the spiral tube and serve as a transport channel for the necessary cooling and flushing fluid during wet drilling with the second core bit 40. The recesses 56A, 56B and 56C are particularly necessary in the case of a small inner gap between the drilled core and the drill shaft. The number of the recesses 56A, 56B and 56C, the geometry of the recesses 56A, 56B and 56C, and the placement of the recesses 56A, 56B and 56C on the outside 53 and/or the inside 54 of the drill shaft 46 can be adjusted according to the quantity of the cooling and flushing fluid.

[0050] The recesses 56A, 56B and 56C provided on the inside 54 of the drill shaft 46 are used for the addition of clean cooling and flushing fluid, and recesses provided on the outside 53 of the drill shaft 46 may facilitate the removal of used cooling and flushing fluid mixed with drilling cuttings. Since the recesses 56A, 56B and 56C for the second core bit 40 are produced before the shaping of the strip material 51, recesses can be produced on the inside 54 of the drill shaft 46 with low manufacturing costs.

[0051] FIG. 5 shows a third embodiment of a core bit 60 according to the invention, which is hereinafter referred to as the third core bit 60. The third core bit 60 comprises a cutting portion 61, a drill-shaft portion 62 and a connecting device 63 that non-releasably connects the cutting portion 61 to the drill-shaft portion 62.

[0052] The cutting portion 61 comprises a ring portion 64 and a plurality of cutting segments 65, which are welded, soldered or screwed to the ring portion 64 or fixed to the ring portion 64 by another suitable method of attachment. The drill-shaft portion 62 comprises a spiral-tube-shaped drill shaft 66, a cover 67 and an insertion end 68, by means of which insertion end the third core bit 60 is fixed in a tool holder of a core drill.

[0053] The drill shaft 66 is configured as a welded spiral tube that has been made from a strip material 71 in the form of a corrugated profiled sheet by means of shaping and welding. The strip material 71 has been shaped 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 member for the drill shaft 66.

[0054] FIGS. 6A, B show a longitudinal section of the third core bit 60 of FIG. 5 along the section line A-A in FIG. 5 (FIG. 6A) as well as a detail of the drill shaft 66 of FIG. 6A in an enlarged view (FIG. 6B).

[0055] The spiral-shaped connection weld 72 of the drill shaft 66 is configured on an outside 73 of the drill shaft 66 and on an inside 74 of the drill shaft 66 to be substantially flush with the shaped strip material 71. The profiled cross-section of the strip material 71 creates recesses on the outside 73 and the inside 74 of the drill shaft 66, by means of which the cooling and flushing fluid can be transported when wet drilling with the third core bit 60. The recesses provided on the inside 74 of the drill shaft 66 are used for the addition of clean cooling and flushing fluid and the recesses provided on the outside 73 of the drill shaft 66 are used for the removal of used cooling and flushing fluid mixed with drilling cuttings. The geometry of the profiled sheet can be adjusted according to the quantity of fluid needed for wet drilling.