TOOL FOR MACHINING A WORKPIECE, IN PARTICULAR DEEP-HOLE DRILL, TOOL SYSTEM AND METHOD

Abstract

A tool for machining a workpiece includes an elongated shaft that has a first shaft end and a second shaft end opposite the first shaft end. A tool head is arranged at the second shaft end. The elongated shaft includes a measuring channel for optical measuring radiation that extends from the first shaft end to the second shaft end. The measuring channel includes an optical measuring surface at an end that faces the second shaft end. The optical measuring surface is configured to reflect optical measuring radiation coupled in via the first shaft end at least partially back to the first shaft end. The optical measuring surface is also configured to vary a property of back-reflected measuring radiation as a function of a relative position of the first shaft end with respect to the second shaft end.

Claims

1-25. (canceled)

26. A tool for machining a workpiece, the tool comprising: an elongated shaft having a first shaft end and a second shaft end opposite the first shaft end; and a tool head arranged at the second shaft end, wherein the elongated shaft comprises a measuring channel for optical measuring radiation, and wherein the measuring channel extends from the first shaft end to the second shaft end, the measuring channel comprising: an optical measuring surface at an end facing the second shaft end, wherein the optical measuring surface is configured to reflect optical measuring radiation coupled in via the first shaft end at least partially back to the first shaft end, and wherein the optical measuring surface is configured to vary a property of back-reflected measuring radiation as a function of a relative position of the first shaft end with respect to the second shaft end.

27. The tool of claim 26, wherein said tool is a deep-hole drill, and wherein the tool head includes a drill head with at least one cutting edge.

28. The tool of claim 26, wherein the optical measuring surface is configured to vary an intensity of the back-reflected measuring radiation as a function of a rotation of the first shaft end relative to the second shaft end.

29. The tool of claim 26, wherein the optical measuring surface includes a gray gradient filter.

30. The tool of claim 29, wherein the gray gradient filter is an angle-dependent gray gradient filter which is configured to vary an intensity of the back-reflected measuring radiation as a function of a rotation of the first shaft end relative to the second shaft end.

31. The tool according to claim 26, wherein the optical measuring surface includes an optical polarizing filter.

32. The tool of claim 31, wherein the optical polarizing filter has a polarization direction which is rotated relative to a polarization direction of the measuring radiation by an angle between 30 and 60.

33. The tool of claim 26, wherein the optical measuring surface is configured to vary a polarization of the back-reflected measuring radiation as a function of a relative position of the first shaft end with respect to the second shaft end.

34. The tool of claim 26, wherein the measuring channel is formed at least in sections by at least one of a rod made of a medium that is transparent to the measuring radiation or a glass.

35. The tool of claim 26, wherein the optical measuring surface includes a waveplate, and wherein the waveplate is a /4 plate.

36. The tool of claim 26, further comprising: at least one coolant lubricant channel, wherein the measuring channel and the coolant lubricant channel are separated from one another.

37. The tool of claim 26, wherein the elongated shaft includes a coolant lubricant channel for a coolant lubricant, the coolant lubricant channel connected to a coolant lubricant outlet at the tool head, and wherein the optical measuring surface is arranged inside the coolant lubricant channel.

38. The tool of claim 37, wherein a wavelength of the optical measuring radiation and a transmission spectrum of the coolant lubricant are adapted to each other such that the coolant lubricant is transparent to the optical measuring radiation.

39. The tool of claim 26, wherein the optical measuring surface is configured as a circular arc section in a plane transverse to a longitudinal direction of the elongated shaft.

40. A tool system for machining a workpiece, the tool system comprising: a tool comprising: an elongated shaft having a first shaft end and a second shaft end opposite the first shaft end; and a tool head arranged at the second shaft end, wherein the elongated shaft comprises a measuring channel for optical measuring radiation, and wherein the measuring channel extends from the first shaft end to the second shaft end, the measuring channel comprising: an optical measuring surface at an end facing the second shaft end, wherein the optical measuring surface is configured to reflect optical measuring radiation coupled in via the first shaft end at least partially back to the first shaft end, and wherein the optical measuring surface is configured to vary a property of back-reflected measuring radiation as a function of a relative position of the first shaft end with respect to the second shaft end; an optical transmitter configured to couple the optical measuring radiation via the first shaft end of the tool and to transmit it to the optical measuring surface; and an optical receiver configured to receive the optical measuring radiation reflected back from the optical measuring surface of the tool to the first shaft end.

41. The tool system of claim 40, wherein the optical receiver comprises a plurality of light-sensitive sensor areas, and wherein the optical receiver is a quadrant sensor.

42. The tool system of claim 40, wherein the optical receiver comprises a polarization sensor.

43. The tool system of claim 40, wherein the optical transmitter and/or optical receiver are arranged in a fixed position with respect to the tool and configured to rotate together with the tool about a longitudinal axis of the elongated shaft during said machining of said workpiece.

44. The tool system according to claim 40, wherein the optical transmitter and the optical receiver are arranged in a measuring adapter which is arranged between the tool and a drive device and/or feed device for the tool.

45. A measuring method for chip formation machining a workpiece for deep-hole drilling, comprising the steps: providing a tool system comprising a tool with an elongated shaft having a first shaft end and a second shaft end opposite the first shaft end and an optical measuring surface configured to reflect optical measuring radiation coupled in via the first shaft end at least partially back to the first shaft end and to vary a property of back-reflected measuring radiation as a function of a relative position of the first shaft end with respect to the second shaft end; coupling the optical measuring radiation via the first shaft end and transmitting the optical measuring radiation to the optical measuring surface with an optical transmitter; receiving the measuring radiation reflected back from the optical measuring surface to the first shaft end with an optical receiver; and determining a relative position of the first shaft end with respect to the second shaft end based on the measuring radiation reflected back from the optical measuring surface and received by the optical receiver with an evaluation device.

Description

[0056] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

[0057] FIG. 1 shows a schematic illustration of a conventional system for deep drilling with a conventional external measuring device;

[0058] FIG. 2 shows a schematic illustration of an embodiment of a tool system comprising a tool according to an aspect of the present disclosure;

[0059] FIG. 3 shows a schematic illustration of a further embodiment of a tool system comprising a tool according to an aspect of the present disclosure;

[0060] FIG. 4 shows a first schematic illustration of a tool according to a first embodiment of the present disclosure in a top view in direction of the longitudinal direction of the shaft;

[0061] FIG. 5 shows a second schematic illustration of a tool according to a second embodiment of the present disclosure in a top view in direction of the longitudinal direction of the shaft;

[0062] FIG. 6 shows a third schematic illustration of a tool according to a third embodiment of the present disclosure in a top view in direction of the longitudinal direction of the shaft;

[0063] FIG. 7 a flow chart of a method.

[0064] FIG. 1 shows a schematic representation of a conventional system 10 for deep-hole drilling. The system 10 comprises a drive device 11 and a deep-hole drill 12 as a tool. As already described above, a challenge in deep-hole drilling is that the deep-hole drill must be guided precisely in order to obtain as accurate a straight drilling path as possible, as illustrated by the dashed line 13. In practice, however, particularly at high machining speeds, deviations from the ideal bore path ant thus in a centerline of the deep hole drill. This is illustrated in FIG. 1 by arrows for compression 2, bending 3, and torsion 4. If one or more of compression 2, bending 3 and torsion 4 of the tool 12 occur during the machining process, this can negatively influence the manufacturing precision and lead to a deviation of the hole from the desired straight hole path.

[0065] In the conventional approach shown in FIG. 1, an external measuring device 14 is provided which measures the bore from the outside through the workpiece 20, for example by ultrasound 15. However, artifacts can occur in the case of complex workpiece geometries or geometries with scattering or reflection centers within the workpiece. For example, existing bores, as indicated in FIG. 1 by reference sign 16, can lead to interference signals which make it impossible to accurately determine the center line of the borehole.

[0066] FIG. 2 shows a schematic representation of an embodiment of a tool system 30 comprising a tool 40 for machining a workpiece according to an aspect of the present disclosure. In the shown example, there is provided a deep-hole drill. However, other tools for machining a workpiece or tools for forming comprising an elongated shaft are also conceivable. The tool 40 comprises an elongated shaft 41 having a first shaft end 42 and a second, in the longitudinal direction opposite shaft end 43. The tool 40 further comprises a tool head 44 which is arranged at the second shaft end 43. The elongated shaft comprises a measuring channel 45 for optical measuring radiation 51, wherein the measuring channel 45 extends from the first shaft end 42 to the second shaft end 43. The measuring channel 45 comprises an optical measuring surface 60 at an end facing the second shaft end 43. The optical measuring surface 60 is configured to reflect optical measuring radiation 51 coupled in via the first shaft end at least partially back to the first shaft end 42, wherein the optical measuring surface 60 is configured to vary a property of the back-reflected measuring radiation 52 as a function of a relative position of the first shaft end 42 with respect to the second shaft end 43. The optical measuring surface 60 can comprise a mirror which is configured to reflect the optical measuring radiation back. In the figures, the incident path of the optical measuring radiation is denoted by reference sign 51. The return path of the optical measuring radiation or the back-reflected optical measuring radiation is denoted by reference sign 52.

[0067] The tool system 30 further comprises an optical transmitter 71 and an optical receiver 72. The optical transmitter 71 is configured to couple optical measuring radiation 51 in via the first shaft end 42 of the tool 40 and to transmit it to the optical measuring surface 60. The optical transmitter can be a laser, for example a laser diode with beam-shaping optics. The optical measuring radiation can be coherent and/or polarized measuring radiation. The optical receiver 72 is configured to receive the measuring radiation 52 reflected back from the optical measuring surface 60 of the tool 40 to the first shaft end 42. The optical receiver 72 can be a photodiode or an array of photodiodes. Preferably, the transmitter 71 and receiver 72 can be arranged in a separate unit 73 which can be flexibly combined with or coupled to different tools 40. For example, the unit 73 can be a measuring adapter 74 which can be arranged between the tool 40 and a drive device and/or feed device for the tool. The drive device (not shown in FIG. 2) can be a conventional drive device 11 as, for example, illustrated in FIG. 1.

[0068] In the embodiment shown in FIG. 2, the optical receiver 72 is configured as a quadrant sensor. However, other types of sensors, such as a sensor comprising a pixel array or a polarization sensor, are also possible. If the tool 40 follows a desired straight path, the back-reflected measurement radiation 52 can strike the center of the quadrant sensor. However, if there is a bend in the longitudinal direction, as illustrated by arrow 3 in FIG. 1, the back-reflected measurement radiation 42 is deflected, as illustrated by the angle between the incident optical measurement radiation 51 and the back-reflected optical measurement radiation 52. Thereby a deviation from a desired straight path can be detected. An amplitude of the deviation is a measure of the tilt of the tool head 44 or the retro-reflective measuring surface 60 at the second shaft end. As already mentioned above, usually only small angular deviations occur during deep-hole drilling, such that an evaluation with a cost-effective quadrant sensor is possible. A further advantage of this embodiment is the compact design, which allows implementation smaller than a diameter of the cutting tool.

[0069] The optical measuring surface 60 can comprise a measuring mirror 61 which is configured to reflect the optical measuring radiation at least partially back to the first shaft end. Optionally, the optical measuring surface 60 can further be configured to vary an intensity of the back-reflected measuring radiation 52 as a function of a rotation of the first shaft end 42 relative to the second shaft end 43. This can be a gray gradient filter 62, in particular an angle-dependent gray gradient filter, which is configured to vary an intensity of the back-reflected measurement radiation 52 as a function of a rotation of the first shaft end 42 relative to the second shaft end 43. Thus, when the second shaft end 43 is rotated relative to the first shaft end 42, the measuring radiation is reflected more strongly or more weakly. This difference in intensity can in turn be evaluated to determine a rotation or torsion of the shaft ends relative to one another.

[0070] As shown in FIG. 2, the tool 40 can comprise a first coolant lubricant channel 46 and/or a second coolant lubricant channel 48. The first coolant lubricant channel 46 can be a coolant lubricant input of feed channel which can feed coolant lubricant to the tool head 44 via an outlet 47. The second coolant channel 48 can be a coolant lubricant return channel, which via an inlet 49 receives coolant lubricant from the tool head and preferably cutting chips and transports them away. It is to be understood that the second coolant lubricant channel 48 can have a larger diameter than the first coolant lubricant channel 46 in order to enable advantageous removal of the cutting chips.

[0071] FIG. 3 shows a schematic illustration of a further embodiment of a tool system 30 comprising a tool 40 according to an aspect of the present disclosure. The tool system comprises a drive and/or feed device 11 and an adapter 74, which is arranged between the drive and/or feed device 11 and the tool 40. The adapter 74 comprises the optical transmitter 71, which is configured to couple optical measuring radiation 51 in via the first shaft end 42 of the tool 40 and to transmit the optical measurement radiation to the optical measuring surface 60. The adapter further comprises the optical receiver 72, which is configured to receive the measuring radiation reflected back from the optical measuring surface 60 of the tool 40 to the first shaft end 42. In the embodiment shown in FIG. 3, a substantially coaxial beam path of the coupled-in measuring radiation 51 and the back-reflected measuring radiation 52 is provided. Hereby, a beam splitter 75 can be provided, which couples the optical measuring radiation 51 into the common beam path. The reflected measurement radiation 52 passes at least partially through the beam splitter and reaches the optical receiver 72.

[0072] The tool system 30 further comprises an evaluation device 88 which is configured to determine a relative position of the first shaft end 42 with respect to the second shaft end 43 based on the measuring radiation 52 received by the optical receiver 72 and reflected back from the optical measuring surface 60.

[0073] In the embodiment shown in FIG. 3, the tool system 30 optionally further comprises a control device 89 which is configured to control or regulate the drive device and/or feed device 11 as a function of or in dependence on the measuring radiation 52 detected by the optical receiver 72 and reflected back by the measuring surface at the second shaft end, for example as already described above.

[0074] The evaluation device 88 and control device 89 can be configured as separate units or as a common unit 80. For example, an industrial control or a microcontroller can be provided. However, it is also possible to provide a control computer which is configured with program instructions to perform the functions of the evaluation device 88 and/or control device 89.

[0075] In the embodiment shown in FIG. 3, the optical measuring surface 60 comprises a measuring mirror 61 and a polarizing filter 63 arranged on top. If polarized measuring radiation, for example from a laser as an optical transmitter 71, passes through the polarization filter 63, it is reflected at the measuring mirror 61, passes through the polarization filter 63 again and is directed to the optical receiver 72 via the beam splitter 75. If the polarization filter 63 is rotated relative to the polarization of the laser light of the incident measuring radiation 51, this leads to a partial attenuation of the reflection. The intensity of the light received by the optical receiver 72 therefore depends on a torsion or rotation of the tool 40. Optionally, the optical receiver 72 can again comprise several pixels in order to also be able to detect a bending of the tool 40.

[0076] In the embodiment shown in FIG. 2, the measuring channel 45 and the coolant lubricant channel 46 are separated from each other. In the embodiment shown in FIG. 3, a common channel 45, 46 is provided, which serves both as a measuring channel 45 and as a coolant lubricant channel 46. This common channel is connected to a coolant lubricant outlet 47 at the tool head 44. The optical measuring surface 60 is arranged inside the coolant lubricant channel 46. An advantage of this embodiment is that the optical measuring radiation 51, 52 and the coolant lubricant can be guided in a common channel and the tool is therefore less complex in design. Hereby, a wavelength of the optical measuring radiation and a transmission spectrum of the coolant lubricant can be adapted to each other such that the coolant lubricant is transparent to the optical measuring radiation. Separate guiding of the optical measuring radiation is thus not necessary.

[0077] FIGS. 4, 5 and 6 show three exemplary schematic illustrations of tools 40 in viewed in a direction in the longitudinal direction of the shaft from the first end 42 towards the second end 43, as shown in FIGS. 2 and 3. The shaft 41 of the tool 40 is configured as a hollow tube. The interior of the tube thereby illustrates the first coolant lubricant channel 46, similar to shown in FIG. 3. The second coolant lubricant channel 48 for returning the coolant lubricant and removing the chips can be arranged outside the shaft 41. Such a shaft 41 can be produced, for example, by an extrusion process or by deformation of an originally circular starting body, on the basis of which the coolant lubricant channel 48 is formed with a wedge shape by deformation from the outside. The optical measuring surface 60 is in turn arranged inside the shaft 41 inside the first coolant lubricant channel 46. The optical measuring surface 60 can be held in the coolant lubricant channel 46 by one or more holders 81 projecting into the coolant lubricant channel 46. In order not to constitute an unduly large obstruction to the flow of the coolant lubricant, the optical measuring surface 60 can comprise one or more passage openings 82 for the coolant lubricant. The respective cutting edges 84 are also illustrated. During machining of the workpiece, a force acts on the cutting edge 84, which leads to torsion of the shaft 41, as illustrated by the arrow 85 in FIG. 4 and FIG. 5.

[0078] In the embodiments shown in FIG. 4 and FIG. 6, the optical measuring surface 60 is provide by a measuring mirror 61 and a polarizing filter 63, as for example illustrated in FIG. 3. In the embodiment shown in FIG. 5, however, a circular arc-shaped gray scale filter is provided. Depending on where the measuring radiation 51 strikes the gray scale filter, the measuring radiation is reflected back to the optical receiver with different intensities. Based on this, a information can be obtained about a torsion of the second shaft end 43 of the tool 40 relative to the first shaft end 42.

[0079] In a modification of the embodiment shown in FIG. 3, a glass rod 91 can optionally be provided, in which the optical measuring radiation 51 is guided at least in sections from the first shaft end 42 to the second shaft end 43 and the reflected measuring radiation 52 is guided back from the second shaft end 43 to the first shaft end 42. This can reduce the transparency requirements for the coolant lubricant. However, the construction is further simplified because no separate channel needs to be provided, instead, the glass rod 91 is simply inserted into the existing coolant lubricant channel 46. In the context of the present disclosure, a glass rod is understood to be an elongated body that is transparent to the measuring radiation and can be inserted into the shaft 41.

[0080] FIG. 7 shows a flow chart of a method 100 for machining a workpiece, in particular for cutting or chip removing machining, in particular for deep-hole drilling. In a first step S101, a tool system comprising a tool as described in the present disclosure is provided. In a second step S102, optical measuring radiation is coupled in via the first shaft end with the optical transmitter and transmitted to the optical measuring surface. In a third step S103, the measuring radiation reflected back from the optical measuring surface to the first shaft end is received with the optical receiver. In a fourth step S104, a relative position of the first shaft end with respect to the second shaft end is determined with the evaluation device based on the measuring radiation reflected back from the optical measuring surface and received by the optical receiver. The determined relative position can be further processed in subsequent steps. For example, a center line can be mapped during deep drilling via a progression of the respective relative positions over time and documented for quality assurance purposes, for example. However, it is also possible that the determined relative position is used to regulate or control the machining process, as already described above.

[0081] In conclusion, the proposed solution allows monitoring of a material processing operation, in particular during deep-hole drilling. A displacement of a measuring beam, such as a laser reference beam, can be detected depending on the axial, radial, and/or transverse displacements of a long-shaft tool. The optical transmitter, in particular a laser beam source which emits coherent light waves, emits the measuring radiation through the measuring channel through the tool shaft. An optical measuring surface, for example a mirror mounted at the end towards the tool head, preferably with a polarization filter/grey gradient filter applied, which is displaced in the same way due to the fixation to the tool head, reflects the measuring radiation onto an optical sensor, for example onto a 4-quadrant/4-point polarization filter. gray gradient filter, which is displaced equally by being fixed to the tool head, reflects the measuring radiation onto an optical sensor, such as a 4-quadrant/photo sensor. With the measuring signal from the optical sensor, for example the measurement of the output voltages/currents at the 4-quadrant/photo sensor, it is possible to determine, on the one hand, the attenuation of the intensity of the measuring beam, for example an attenuation of the power of the laser beam by the gray gradient filter or the rotation of the polarization direction due to the polarization filter, and on the other hand the displacement of the laser point by the tilting of the mirror.

[0082] With the solutions proposed herein, a tool for machining a workpiece, in particular a deep-hole drill, as well as a corresponding tool system and method can be provided, which can contribute to achieving an improved drilling result. In particular, an improved monitoring of the machining process can be provided even for complex workpieces, in particular with a plurality of adjacent deep holes, with high accuracy.