Tool for machining a workpiece, in particular a deep-hole drill, tool system and method

Abstract

The invention relates to a tool (40) for machining a workpiece (20), in particular by chip-removal, in particular to a deep-hole drill (12), comprising an elongated shank (41) having a first shank end (42) and a second shank end (43) opposite thereto, and a tool head (44) which is located at the second shank end, wherein: the shank comprises a measurement channel (45) for optical measurement radiation (51, 52); the measurement channel extends from the first shank end to the second shank end; the measurement channel comprises an optical measurement face (60) at an end facing the second shank end; the optical measurement face (51) is designed to reflect at least a portion of the optical measurement radiation that has been coupled in via the first shank end back to the first shank end; and the optical measurement face is designed to vary a property of the back-reflected measurement radiation (52) according to a relative position of the first shank end with respect to the second shank end. The invention also relates to an associated tool system (30) and to a measurement method for machining a workpiece, in particular by chip-removal, in particular for deep drilling.

Description

Tool for machining a workpiece, in particular deep drill, tool system and method

[0001] The present invention relates to a tool for machining a workpiece, in particular a deep drill, as well as a corresponding system and method, in particular for deep drilling.

[0002] Deep hole drilling, also known as deep drilling, is a part of modern machining technology, particularly in metalworking. Deep hole drilling is used to machine camshafts, drive shafts, injectors, and drill rods in the automotive industry, as well as filler pipes, ejectors, nozzles, and so on in the food industry.

[0003] Deep hole drilling is a special drilling process with drilling depths that are many times greater than the diameter. According to VDI Guideline 3210 (VDI Guideline 3210, Beuth-Verlag Berlin, 2006), deep hole drilling processes are machining processes for producing and machining holes with diameters between D = 0.2...2000 mm and hole depths that are usually greater than three times, and in particular greater than ten times, the diameter. For small hole diameters, length-to-diameter ratios of up to l / D < 100 can be achieved, and in special cases even up to 1 / D = 900 can be achieved. For large diameters, the I / D ratio is usually limited by the travel of the machine or by its bed length.

[0004] Deep drilling (also known as deep hole drilling or gun drilling) is a metal-cutting manufacturing process in metalworking in which the drilling depth is significantly greater than the tool diameter. Within the scope of the present disclosure, a deep drilling or deep hole drilling can be defined as a drilling in which the drilling depth is at least three times, in particular at least five times, in particular at least ten times, and in particular at least twenty times the diameter. The deep drilling process is also economically attractive because it can be carried out remarkably quickly and can enable a high surface quality as well as excellent hole quality during drilling.In addition, deep drilling can be distinguished from other common drilling processes by the use of a cooling lubricant, which is pumped under high pressure through the hole to the cutting point on the workpiece.

[0005] The cooling lubricant lubricates and cools the bore area between the workpiece and the tool and ensures smooth chip removal during deep hole drilling. With its large I / D ratios (length or depth: I; diameter: D), the high-pressure cooling lubricant supply, and the associated chip removal from the cutting area, deep hole drilling presents a particular challenge in modern machining technology. A distinction is made between three classic deep hole drilling methods: (1) deep hole drilling with a single-lip drill (ELB), (2) deep hole drilling using the BTA deep hole drilling method based on the Boring and Trepanning Association principle, and (3) deep hole drilling with an ejector-type deep hole drill.

[0006] With single-lip drills, the cooling lubricant is supplied through a cooling channel integrated into the tool and removed with the chips through a V-shaped groove in the drill shank, the so-called bead. Single-lip drills are used for holes with a diameter typically ranging from 0.5 to approximately 200 mm. For this deep drilling process, the cooling lubricant is pumped with sufficient pressure through the drill's cooling channel, exits at the cutting head, and flows past the cutting edge of the drill. Deep drilling with a single-lip drill can be achieved if a sufficiently large amount of cooling lubricant is available during drilling.

[0007] BTA drilling stands for "Boring and Trepanning Association." In this deep drilling process, the cooling lubricant is supplied from the outside and the chips are removed from the inside. The cooling lubricant of the deep drilling machine is fed to the deep drilling tool (core drilling tool) via a drilling oil supply device and a special seal. BTA drilling is a so-called single-tube system, as it requires a single drill pipe for deep drilling. This makes it particularly suitable for the production of large series or serial production for deep drilling in contract manufacturing. In BTA drilling, the core is drilled out of the hole.

[0008] Ejector deep drilling is a variation of the BTA deep drilling process, in which the cooling lubricant is fed to the workpiece or the cutting point via an ejector connector. The cooling lubricant is supplied through a space between the drill pipe and the inner pipe, which is why the process is also called the "twin-pipe process." In this type of deep drilling, the chips are transported to the outside through an inner pipe.

[0009] In addition to metals such as steel and non-ferrous metals, other materials such as acrylic glass, duroplastics and thermoplastics and hardwood can also be provided with deep holes.

[0010] One challenge in deep hole drilling is precisely guiding the deep hole drill to achieve the most straight hole path possible, i.e., a center line with the smallest possible deviations. Similar challenges generally arise with tools for machining workpieces with an elongated shank, which are generally used for machining and / or forming workpieces.

[0011] WO 2005 / 072897 A2 describes a device for drilling a borehole in a workpiece with a diameter D of a drill and a depth of the borehole. known, where the ratio of depth to diameter D is greater than 100. In order to ensure that the borehole can be drilled with the desired spatial longitudinal progression, an additional external measuring device is provided. The external measuring device has a measuring head with the aid of which the spatial longitudinal progression of the borehole or the current position of the drill head of the drill can be measured. This is achieved by measuring a radial distance of the drill head or the borehole from a surface of the workpiece closest to the borehole. The measuring head of the external measuring device is mounted on a measuring head carrier with the aid of which it can be moved along the surface of the workpiece to be machined and its spatial position can be aligned relative to the workpiece to be machined.

[0012] In other words, in the prior art solution, a measurement is performed with an external measuring device perpendicular to the longitudinal direction of the bore through the workpiece to be machined. The inventors recognized that one problem with this approach is that, for complex workpieces with a large number of bores or complex surfaces, artifacts can occur during the measurement, and measuring the center line is not possible with the required accuracy.

[0013] Against this background, it is an object of the present invention to provide a tool, in particular a deep hole drill, for machining a workpiece, as well as a corresponding system and method, which can contribute to achieving improved drilling results. In particular, it would be desirable to enable improved monitoring of the machining process, even with complex workpieces, especially with a plurality of adjacent deep holes, with high precision.

[0014] The claimed subject matter is defined in the independent claims. Advantageous embodiments and further developments are described in the dependent claims.

[0015] According to a first aspect of the invention, it is proposed to provide a tool for machining a workpiece, in particular for machining a workpiece, in particular a deep drill, having an elongated shaft with a first shaft end and a second, (in the longitudinal direction) opposite shaft end, a tool head which is arranged at the second shaft end, wherein the shaft has a measuring channel for optical measuring radiation, wherein the measuring channel extends from the first shaft end to the second shaft end, wherein the measuring channel has an optical measuring surface at an end facing the second shaft end, wherein the optical measuring surface is configured to at least partially reflect optical measuring radiation coupled in via the first shaft end back to the first shaft end, wherein the optical measuring surface is configured toto vary a property of the reflected measuring radiation depending on a relative position of the first shaft end to the second shaft end.,

[0016] According to a further aspect of the present invention, a tool system for, in particular, machining a workpiece, in particular a system for deep drilling, is proposed, comprising a tool for, in particular, machining a workpiece, in particular a deep drill, as described above and to be explained below; an optical transmitter configured to couple optical measuring radiation via the first shank end of the tool and transmit it to the optical measuring surface; an optical receiver configured to receive the measuring radiation reflected back from the optical measuring surface of the tool to the first shank end.

[0017] According to a further aspect of the present invention, a measuring method for machining a workpiece, in particular for deep drilling, is proposed, comprising the steps: Providing a tool system with a tool as described above and to be explained below; Coupling optical measuring radiation via the first shaft end and transmitting the optical measuring radiation to the optical measuring surface with the optical transmitter; Receiving the measuring radiation reflected back from the optical measuring surface to the first shaft end with the optical receiver; Determining the relative position of the first shaft end to the second shaft end based on the measuring radiation received by the optical receiver and reflected back from the optical measuring surface with the evaluation device.

[0018] The inventors recognized that tools used to machine a workpiece with an elongated shank and a tool head arranged at this shank end can lead to positional deviations of the tool head, particularly axial deviations from a central axis. It would therefore be desirable to be able to determine the center line. For example, in experiments, a deviation of up to 8 mm was measured during deep drilling over a length of 1700 mm. Deviations in the center line can occur, particularly at high feed rates for rapid material processing. However, high operating speeds are essential for the economical production of workpieces.

[0019] While it is possible to determine the position of the tool head or the path of the drill hole in the workpiece using external measurements, for example, using ultrasound, with known solutions from the outside, such as in the aforementioned WO 2005 / 072897 A2, a disadvantage of these known solutions is that the measurement of axial deviations from the outside, for example in prismatic components, is only possible to a limited extent. Accurate measurements are also not possible for components with shadows, excessive residual wall thicknesses, or consecutive holes. The method described in the prior art therefore has a narrowly defined area of ​​application for external measurements, predominantly for cylindrical components.

[0020] It is therefore proposed that the elongated shaft of the tool for machining the workpiece already has a measuring channel for optical measuring radiation. At the second shaft end, ie the shaft end facing the tool head, a defined optical measuring surface is provided. This means that the measurement can be carried out within the tool itself, without being affected by complex geometries of the workpiece or by existing holes in the workpiece. The optical measuring surface can be provided directly on the shank end, i.e. between the cutter end and a tool head. This facilitates production thanks to the very good accessibility. Furthermore, an existing shank can also be easily retrofitted by attaching a corresponding optical measuring surface to the shank end or by introducing it into the measuring channel in the area of ​​the shank end, for example into an already existing coolant channel. The optical measuring surface is designed to at least partially reflect optical measuring radiation coupled in via the first shank end back to the first shank end.The optical measuring surface is further configured to vary a property of the reflected measuring radiation depending on a relative position of the first shaft end to the second shaft end. The reflected measuring radiation can be received and evaluated by an optical receiver arranged at the first shaft end facing away from the tool head. For example, a bend of the shaft transverse to the longitudinal direction leads to an axial deflection of the reflected beam. In this case, the varied property of the reflected measuring radiation is the varied direction of the reflected reflection. Thus, an angle at the second shaft end or at the tool head and thus an orientation of the tool head in the workpiece can be determined by the optical receiver measuring the axial deflection. For this purpose, the optical receiver can have multiple sensor surfaces or be designed as a quadrant sensor.Furthermore, torsion of the elongated shaft results in the first shaft end, at which the optical receiver receives the reflected measuring radiation, and the second shaft end, at which the tool head is arranged, being rotated relative to one another. The optical measuring surface can, for example, have a gray gradient filter or a polarization filter that is angle-dependent in a torsion plane transverse to the longitudinal direction of the shaft, so that the intensity of the reflected measuring radiation varies depending on the rotation of the first shaft end relative to the second shaft end. The relative position of the first shaft end to the second shaft end can thus be monitored during the machining of the workpiece. In particular, a momentary deviation of the tool head of a long-shank hollow tool from a tool center can be determined. This allows a time-dependent absolute The position of the tool head can also be determined in a confined / enclosed space, even with complex surrounding geometries that would make measurement from the outside impossible.

[0021] The proposed tool can be used to measure, in particular in real time, one or more of bending, compression, torsion in an elongated shank of a tool for machining a workpiece, in particular in a deep hole drill.

[0022] The tool head can have at least one cutting edge for machining the workpiece. However, it is also possible to provide two or more cutting edges. Preferably, an asymmetrical cutting edge can be provided. If the tool is subjected to different angular positions with different pressure in the feed direction or in the longitudinal direction of the shaft, the direction in which the tool moves through the workpiece to be machined can be influenced. For example, a deep drill can be steered to a certain extent in this way. By evaluating the optical measuring radiation reflected back from the optical measuring surface arranged in the region of the second shaft end, the relative position of the cutting end and the tool head can be determined. This enables more precise control and thus greater precision.

[0023] The tool can be a deep hole drill, with the tool head comprising a drill head or drill bit with at least one cutting edge. Particularly in very long holes with a small diameter or a high length-to-diameter ratio, deviations in the tool center can easily occur. With the proposed solution, these deviations can be monitored and optionally corrected via an additional actuator (not defined here) or by varying the feed rate.

[0024] The optical measuring surface can be configured to vary the intensity of the reflected measuring radiation depending on the rotation of the first shaft end relative to the second shaft end. For example, the optical measuring surface can have a gray gradient filter. In particular, an angle-dependent gray gradient filter be provided, which is designed to vary an intensity of the reflected measuring radiation depending on a rotation of the first shaft end relative to the second shaft end.

[0025] Alternatively or additionally, the optical measuring surface can be configured to vary the polarity of the reflected measurement radiation depending on the relative position of the first shaft end to the second shaft end. For example, the optical measuring surface can have an optical polarization filter.

[0026] One advantage of the above embodiments can be that the intensity of the reflected measuring radiation can be used to determine a relative position, in particular a torsion or twisting of the elongated shaft. Particularly at high feed rates, a higher force can act on a cutting edge of the tool head and lead to a torsion of the shaft about its longitudinal axis. For a tool length or shaft length of 1700 mm, a typical twist can be in the range of 0-30°, in particular in the range of 0-10°, in particular in the range of 0-5°. One advantage of the graduated gray filter is its simple and cost-effective production. One advantage of the polarization filter is that the twisting can be determined independently of any lateral deviation, in particular essentially independently of any bending or deflection of the shaft transverse to the longitudinal direction.

[0027] The optical polarization filter can have a polarization direction that is rotated by an angle between 30° and 60° relative to the polarization direction of the measurement radiation. An advantage of this design can be increased sensitivity. Because the polarization filter is already rotated relative to the measurement radiation, for example, by 45°, even small angle changes cause a large change in the reflected measurement radiation. If, however, the polarization direction of the polarization filter approximately corresponds to the polarization of the measurement radiation, small angle changes would only cause a small change in intensity.

[0028] The measuring channel can be formed, at least in section, by a rod made of a medium that is transparent to the measuring radiation, in particular a glass rod. The rod made of the transparent medium can be designed to bring about a change in the polarization of the measuring radiation, in particular as a function of the mechanical stresses. In other words, a change in the polarity of the measuring radiation can be brought about not only by a polarization filter on the measuring surface, but alternatively or additionally also already in the course of the measuring channel by a rod made of a medium that is transparent to the measuring radiation. Mechanical stresses are to be understood in particular as mechanical stresses acting on the shaft and / or the rod, which can be caused by torsion, bending or compression of the shaft and / or rod.

[0029] The optical measuring surface can comprise a wave plate, in particular an λ / 4 or λ / 2 plate. This is another possibility for influencing a property of the reflected measuring radiation in order to use the reflected measuring radiation to determine the relative position of the first shaft end to the second shaft end.

[0030] The measuring channel can be an internal hollow channel of the shaft. One advantage of this design is that the optical measuring radiation can be guided within the shaft in a protected manner. For example, this can prevent chips from distorting the measurement result.

[0031] Optionally, the tool can have at least one additional cooling lubricant channel, wherein the measuring channel and the cooling lubricant channel are separated from each other. In the context of the present disclosure, a cooling lubricant channel can be understood as a channel for a coolant and / or lubricant. Such cooling lubricants are usually used in cutting tool machining. The cooling lubricant channel can be connected to a cooling lubricant outlet on the tool head. An advantage of this solution can be that the measuring channel is protected from interference. Optionally, the measuring channel can be designed as a rod made of a transparent medium, in particular as a glass rod. In particular, the rod made of the transparent medium or glass rod can be installed in an already existing cooling A lubricant channel can be arranged or inserted into it. This simplifies manufacturing, as the jet-guiding area can automatically be considered oil-tight due to displacement. For example, existing shaft profiles can be used and subsequently expanded to include a measuring channel. In addition to a cooling lubricant channel for supplying the cooling lubricant, another cooling lubricant channel can be provided for removing the cooling lubricant and any chips generated during machining of the workpiece.

[0032] The shaft can have a cooling lubricant channel for a cooling lubricant, which is connected to a cooling lubricant outlet on the tool head, with the optical measuring surface arranged in the cooling lubricant channel. In other words, the optical measuring surface can be arranged directly in the cooling lubricant channel. It is not necessary to provide a separate cooling lubricant channel for supplying the cooling lubricant. Instead, the measuring channel and cooling lubricant channel are formed by the same channel. This offers a synergistic effect, as the cooling lubricant can be guided directly in the measuring channel. This allows the tool to be manufactured more simply and cost-effectively.

[0033] In a further development, the optical measuring surface can be held in the cooling lubricant channel by means of one or more holders extending into the cooling lubricant channel. In particular, the optical measuring surface can have one or more passage openings for the cooling lubricant.

[0034] A wavelength of the optical measuring radiation and a transmission spectrum of the cooling lubricant can be adapted to one another in such a way that the cooling lubricant is transparent to the optical measuring radiation. In other words, a wavelength or a spectrum of the optical transmitter can be adapted to a transmission of the cooling lubricant. Alternatively, a transmission of the cooling lubricant can be adapted to the wavelength of the optical transmitter. The measuring radiation can thus be guided together with the cooling lubricant in the same channel. It is understood that transparent in this context means that there is sufficient optical transmission to perform the measurement, for example, a transmission of at least 50%, in particular at least 70%, in particular at least 80%, in particular at least 90%.

[0035] The optical measuring surface can be designed as a circular arc section in a plane transverse to a longitudinal direction of the elongated shaft. In particular, the optical measuring surface can be designed as a circular arc-shaped gray graduated filter, wherein the intensity of the back-reflected optical measuring radiation varies depending on a position on the circular arc, for example, continuously increasing or decreasing depending on the angle. In the context of the present disclosure, a gray graduated filter is to be understood as an optical element in which the intensity of the back-reflected measuring radiation varies in a continuously increasing or decreasing manner. In particular, if the measuring channel and the cooling lubricant channel are formed by a common channel in the elongated shaft, the design of the optical measuring surface as a circular arc section can be advantageous, since sufficient space can be provided for a cooling lubricant flow.

[0036] A ratio of a length of the shaft to a diameter of the tool head can have a value of not less than 3, in particular not less than 5, in particular not less than 10, in particular not less than 20, in particular not less than 50. In particular, the tool can be a deep drill. It is understood that the elongated shaft can also be made up of several pieces, i.e., composed of several sections. It is also possible for additional shaft sections to be inserted between the tool head and a drive device during a drilling process in order to achieve a desired drilling depth.

[0037] The tool head can have a diameter of at least 5 mm, in particular of at least 10 mm, in particular of at least 15 mm. For example, the tool head has a diameter of 18-21 mm and the elongated shaft has a length of at least 1500 mm, in particular a length of 1700 mm.

[0038] The tool system may further comprise an evaluation device which is configured to determine a relative position of the first shaft end to the second shaft end based on the measurement radiation reflected back from the optical measuring surface received by the optical receiver. The evaluation device can be designed as a separate unit, for example, a computer, a microprocessor, a microcontroller, or any other computing device configured to evaluate measurement data based on measurement signals from the optical receiver.

[0039] The tool system can comprise a drive device and / or feed device for the tool and a control device, wherein the control device is configured to control or regulate the drive device and / or feed device as a function of the measuring radiation detected by the optical receiver and reflected by the measuring surface at the second shaft end. If, for example, a deviation from a desired position is detected, a position correction can be made. For example, as described above, a tool with an asymmetrical cutting edge arrangement can be provided, and a change in direction in the workpiece can be effected by applying pressure to the tool that varies depending on the angle.

[0040] The optical receiver (optical sensor) can have multiple light-sensitive sensor areas. In particular, the optical receiver can be a quadrant sensor or, more generally, be designed as a sensor with multiple sensor surfaces. If, for example, the optical measuring surface is tilted, the reflected optical measuring radiation is thrown back at an angle, so that a deviation of the reflected measuring radiation can be detected by the multiple light-sensitive sensor areas. Based on a deviation determined on the optical sensor and a length of the shaft or distance between the optical sensor and the optical measuring surface, a tilt angle can be determined. By being able to determine the tilt at any time and by also tracking the feed rate of the tool, a position or the center line of, for example, a deep borehole can be determined at any time.

[0041] Alternatively or additionally, the optical receiver can have a polarization sensor. This allows rotation to be measured, as described above. For example, the polarization sensor can comprise an array of sensors with differently arranged polarization filters.

[0042] The optical transmitter and / or optical receiver can be arranged stationary relative to the tool. The optical transmitter and / or optical receiver can, in particular, be arranged and configured to rotate together with the tool around a longitudinal axis of the shaft during machining of the workpiece. This can be particularly advantageous for tracking angular deviations during rotation.

[0043] In one embodiment, the optical transmitter and the optical receiver can be arranged in a measuring adapter, which is arranged between the tool and a drive device and / or feed device for the tool. An advantage of this embodiment can be that existing machines can also be retrofitted with little effort. For example, the measuring adapter can be arranged between a drive spindle of a conventional deep drilling machine and a tool described in the context of this disclosure.

[0044] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0045] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 is a schematic representation of a conventional deep drilling system with a conventional external measuring device; Fig. 2 is a schematic representation of an embodiment of a tool system with a tool according to one aspect of the present disclosure Fig. 3 is a schematic representation of another embodiment of a tool system including a tool according to an aspect of the present disclosure; Fig. 4 is a first schematic representation of a tool according to a first embodiment of the present disclosure in a plan view in the direction of the longitudinal direction of the shaft; Fig. 5 is a second schematic representation of a tool according to a second embodiment of the present disclosure in a plan view in the direction of the longitudinal direction of the shaft; Fig. 6 is a third schematic representation of a tool according to a third embodiment of the present disclosure in a plan view in the direction of the longitudinal direction of the shaft; Fig. 7 is a flowchart of a method.

[0046] Fig. 1 shows a schematic representation of a conventional system 10 for deep drilling. The system 10 has a drive device 11 and a deep hole drill 12 as a tool. As already described at the beginning, one challenge in deep hole drilling is that the deep hole drill is guided precisely in order to achieve the most accurate, straight hole path possible, as shown by the dashed line 13. In practice, however, particularly at high machining speeds, deviations from the ideal hole path and thus a center line of the deep hole drill can occur. This is shown 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 impact the manufacturing precision and lead to a deviation of the hole from the desired straight hole path.

[0047] In the conventional solution shown in Fig. 1, an external measuring device 14 is provided, which measures the bore from the outside through the workpiece 20, for example, using ultrasound 15. However, complex workpiece geometries or geometries with scattering or reflection centers within the workpiece can lead to artifacts. For example, existing bores, as indicated by reference numeral 16 in Fig. 1, can lead to interference signals that make an accurate determination of the borehole's centerline impossible.

[0048] Fig. 2 shows a schematic representation of an embodiment of a tool system 30 with a tool 40 for machining a workpiece according to one aspect of the present disclosure. In the example shown, this is a deep drill. However, other tools for machining a workpiece or tools for forming with an elongated shaft are also conceivable. The tool 40 has an elongated shaft 41 with a first shaft end 42 and a second, longitudinally opposite shaft end 43. The tool 40 further has a tool head 44, which is arranged at the second shaft end 43. The elongated shaft has 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 has an optical measuring surface 60 at an end facing the second shaft end 43.The optical measuring surface 60 is configured to at least partially reflect optical measuring radiation 51 coupled in via the first shaft end 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 depending on a relative position of the first shaft end 42 to the second shaft end 43. The optical measuring surface 60 can have a mirror configured to back-reflect the optical measuring radiation. In the figures, the forward path of the optical measuring radiation is designated by reference numeral 51. The return path of the optical measuring radiation, or the back-reflected optical measuring radiation, is designated by reference numeral 52.

[0049] 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 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 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. In the drive device (in Fig.2 not shown) it may be a conventional drive device 11 as shown for example in Fig. 1.

[0050] In the embodiment shown in Fig. 2, the optical receiver 72 is designed as a quadrant sensor. However, other types of sensors are also conceivable, such as a sensor with a pixel array or a polarization sensor. If the tool 40 follows a desired straight path, the reflected measuring radiation 52 can impinge centrally on the quadrant sensor. However, if there is a bend in the longitudinal direction, as shown by arrow 3 in Fig. 1, the reflected measuring radiation 42 is deflected, as shown by the angle α between the incident optical measuring radiation 51 and the reflected optical measuring radiation 52. This allows a deviation from a desired straight path to be detected. The amplitude of the deviation is a measure of the tilt of the tool head 44 or of the reflected measuring surface 60 at the second shaft end.As mentioned at the beginning, deep drilling typically involves only small angular deviations, making evaluation possible with a cost-effective quadrant sensor. A further advantage of this design is its compact construction, which allows for implementation smaller than the diameter of the cutting tool.

[0051] The optical measuring surface 60 can have a measuring mirror 61 which is designed to at least partially redirect the optical measuring radiation to the first shaft end. reflect. Optionally, the optical measuring surface 60 can further be configured to vary an intensity of the back-reflected measuring radiation 52 depending on 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 measuring radiation 52 depending on a rotation of the first shaft end 42 relative to the second shaft end 43. Therefore, if the second shaft end 43 is rotated relative to the first shaft end 42, the measuring radiation is reflected more or less strongly. This intensity difference can in turn be evaluated to determine a twist or torsion of the shaft ends relative to one another.

[0052] As shown in Fig. 2, the tool 40 can have a first cooling lubricant channel 46 and / or a second cooling lubricant channel 48. The first cooling lubricant channel 46 can be a cooling lubricant supply, which can supply cooling lubricant to the tool head 44 via an outlet 47. The second cooling lubricant channel 48 can be a cooling lubricant return, which receives and removes cooling lubricant from the tool head and preferably cutting chips via an inlet 49. It is understood that the second cooling lubricant channel 48 can have a larger diameter than the first cooling lubricant channel 46 in order to enable the best possible removal of the cutting chips.

[0053] Fig. 3 shows a schematic representation of another embodiment of a tool system 30 with a tool 40 according to one aspect of the present disclosure. The tool system has 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 contains the optical transmitter 71, which is configured to couple optical measuring radiation 51 via the first shaft end 42 of the tool 40 and transmit it to the optical measuring surface 60. The adapter further contains 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 measuring radiation 51 and the returned reflected measuring radiation 52 is provided. For this purpose, a beam splitter 75 can be provided, which reflects the optical measuring radiation 51 into the common beam path. The reflected measuring radiation 52 passes at least partially through the beam splitter and reaches the optical receiver 72.

[0054] The tool system 30 further comprises an evaluation device 88 which is configured to determine a relative position of the first shaft end 42 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.

[0055] 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 the measuring radiation 52 detected by the optical receiver 72 and reflected by the measuring surface at the second shaft end, for example as already described in the introduction.

[0056] The evaluation device 88 and control device 89 can be implemented as separate units or as a single unit 80. For example, this can be an industrial controller or a microcontroller. However, it is also conceivable to provide a control computer configured to execute the functions of the evaluation device 88 and / or control device 89 using program instructions.

[0057] In the embodiment shown in Fig. 3, the optical measuring surface 60 has a measuring mirror 61 and a polarization filter 63 located above it. If polarized measuring radiation, for example from a laser as optical transmitter 71, passes through the polarization filter 63, it is reflected by the measuring mirror 61, passes through the polarization filter 63 again and is guided via the beam splitter 75 to the optical receiver 72. 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 may again have several pixels in order to be able to detect a bending of the tool 40.

[0058] In the embodiment shown in Fig. 2, the measuring channel 45 and the cooling lubricant channel 46 are separate from one another. In the embodiment shown in Fig. 3, a common channel 45, 46 is provided, which serves both as the measuring channel 45 and as the cooling lubricant channel 46. This common channel is connected to a cooling lubricant outlet 47 on the tool head 44. The optical measuring surface 60 is arranged in the cooling lubricant channel 46. An advantage of this configuration is that the optical measuring radiation 51, 52 and the cooling lubricant can be guided in a common channel, and the tool is thus less complex. In this case, a wavelength of the optical measuring radiation and a transmission spectrum of the cooling lubricant can be adapted to one another in such a way that the cooling lubricant is transparent to the optical measuring radiation. Separate guidance of the optical measuring radiation is therefore not necessary.

[0059] Figures 4, 5 and 6 show three exemplary schematic representations of tools 40 in a viewing 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 designed as a hollow tube. The interior of the tube represents the first cooling lubricant channel 46, similar to that shown in Fig. 3. The second cooling lubricant channel 48 for returning the cooling lubricant and for removing the chips can be located outside the shaft 41. Such a shaft 41 can be produced, for example, by means of an extrusion process or by deforming an originally circular starting body, on the basis of which the cooling lubricant channel 48 is formed into a wedge shape by deformation from the outside. The optical measuring surface 60 is in turn arranged within the shaft 41 in the first cooling lubricant channel 46.The optical measuring surface 60 can be held in the coolant channel 46 by means of one or more holders 81 extending into the coolant channel 46. To avoid excessive obstruction to the flow of the coolant, the optical measuring surface 60 can have one or more passage openings 82 for the coolant. Furthermore, the respective cutting edges 84 are shown. During machining, During machining of the workpiece, a force acts on the cutting edge 84, which leads to a torsion of the shaft 41, as shown by the arrow 85 in Fig. 4 and Fig. 5.

[0060] In the embodiments shown in Fig. 4 and Fig. 6, the optical measuring surface 60 is formed by a measuring mirror 61 and a polarization filter 63, as shown, for example, in Fig. 3. In the embodiment shown in Fig. 5, however, a circular arc-shaped grayscale filter is provided. Depending on where the measuring radiation 51 impinges on the grayscale filter, the measuring radiation is reflected back to the optical receiver with varying intensity. Based on this, a statement can be made regarding a torsion of the second shaft end 43 of the tool 40 relative to the first shaft end 42.

[0061] 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 allows the requirements for the transparency of the cooling lubricant to be reduced. However, the structure is still simple, since no separate channel needs to be provided; instead, the glass rod 91 is simply inserted into the existing cooling 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.

[0062] Fig. 7 shows a flow diagram of a method 100 for, in particular, machining a workpiece, in particular for deep drilling. In a first step S101, a tool system with a tool is provided, as described in the context of the present disclosure. In a second step S102, optical measuring radiation is coupled in via the first shaft end using 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 by the optical receiver. In a fourth step S104, a relative position of the first shaft end to the second shaft end is determined based on the measuring radiation reflected back from the optical measuring surface received by the optical receiver using the The determined relative position can be further processed in subsequent steps. For example, a center line during deep drilling can be mapped using a progression of the respective relative positions over time and documented, for example, for quality assurance purposes. However, it is also possible for the determined relative position to be used to regulate or control the machining process, as described above.

[0063] In summary, the proposed solution enables monitoring of a material processing operation, particularly during deep 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-shanked tool. The optical transmitter, in particular a laser beam source emitting coherent light waves, radiates the measuring beam through the measuring channel through the tool shank. An optical measuring surface attached to the end facing the tool head, for example, a mirror attached to a rear side of the tool head, preferably with an applied polarization filter / graduated gray filter, which is similarly displaced due to its attachment to the tool head, reflects the measuring beam onto an optical sensor, such as a 4-quadrant / photo sensor.The measurement signal of the optical sensor, for example the measurement of the output voltages / currents at the 4-quadrant / photo sensor, can be used 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 spot due to the tilting of the mirror.

[0064] The solutions proposed herein can provide a tool for machining a workpiece, in particular a deep hole drill, as well as a corresponding tool system and method, which can contribute to achieving improved drilling results. In particular, improved monitoring of the machining process can be enabled, even with complex workpieces, especially with a plurality of adjacent deep holes with high precision.

Claims

Patent claims 1. A tool (40) for machining a workpiece (20), in particular a deep drill, comprising an elongated shaft (41) with a first shaft end (42) and a second, opposite shaft end (43), a tool head (44) arranged at the second shaft end (43), characterized in that the shaft (41) has a measuring channel (45) for optical measuring radiation (51, 52), wherein the measuring channel (45) extends from the first shaft end (42) to the second shaft end (43), wherein the measuring channel (45) has an optical measuring surface (60) at an end facing the second shaft end (43), wherein the optical measuring surface (60) is configured to at least partially reflect optical measuring radiation (51) coupled in via the first shaft end (42) back to the first shaft end, wherein the optical measuring surface (60) is configured toto vary a property of the reflected measuring radiation (52) depending on a relative position of the first shaft end (42) to the second shaft end (43).

2. Tool according to claim 1, wherein the tool head (44) has at least one cutting edge (84) for machining the workpiece (20).

3. Tool according to one of the preceding claims, wherein the tool (40) is a deep drill, wherein the tool head (44) has a drill head with at least one cutting edge (84).

4. Tool according to one of the preceding claims, wherein the optical measuring surface (60) is configured to vary an intensity of the reflected measuring radiation (52) depending on a rotation of the first shaft end (42) relative to the second shaft end (43).

5. Tool according to one of the preceding claims, wherein the optical measuring surface (60) has a gray gradient filter, in particular an angle-dependent gray gradient filter (62), which is designed to vary an intensity of the back-reflected measuring radiation (52) depending on a rotation of the first shaft end (42) relative to the second shaft end (43).

6. Tool according to one of the preceding claims, wherein the optical measuring surface (60) has an optical polarization filter (63); in particular wherein the optical polarization filter has a polarization direction that is rotated by an angle between 30° and 60° relative to a polarization direction of the measuring radiation (51).

7. Tool according to one of the preceding claims, wherein the optical measuring surface (60) is configured to vary a polarity of the reflected measuring radiation (52) depending on a relative position of the first shaft end (42) to the second shaft end (43).

8. Tool according to one of the preceding claims, wherein the measuring channel (45) is formed at least in sections by a rod made of a medium transparent to the measuring radiation (51, 52), in particular a glass rod; in particular wherein the rod made of the transparent medium is configured to effect a change in the polarization of the measuring radiation (51, 52).

9. Tool according to one of the preceding claims, wherein the optical measuring surface (60) comprises a wave plate, in particular an A / 4 plate.

10. Tool according to one of the preceding claims, wherein the measuring channel (45) is an inner hollow channel of the shaft (41).

11. Tool according to one of the preceding claims, wherein the tool (40) additionally has at least one cooling lubricant channel (46, 48), and wherein the measuring channel (45) and the cooling lubricant channel (46, 48) are separated from each other.

12. Tool according to one of the preceding claims, wherein the shaft (41) has a cooling lubricant channel (46) for a cooling lubricant, which is connected to a cooling lubricant outlet (47) on the tool head, wherein the optical measuring surface (60) is arranged in the cooling lubricant channel (46).

13. Tool according to claim 12, wherein the optical measuring surface (60) is held in the cooling lubricant channel (46) by means of one or more holders (81) projecting into the cooling lubricant channel (46), in particular wherein the optical measuring surface (60) has one or more passage openings (82) for the cooling lubricant.

14. Tool according to claim 12 or 13, wherein a wavelength of the optical measuring radiation (51, 52) and a transmission spectrum of the cooling lubricant are adapted to one another such that the cooling lubricant is transparent to the optical measuring radiation (51, 52).

15. Tool according to one of the preceding claims, wherein the optical measuring surface (60) is formed as a circular arc section in a plane transverse to a longitudinal direction of the elongate shaft (41).

16. Tool according to one of the preceding claims, wherein a ratio of a length of the shaft (41) to a diameter of the tool head (44) has a value of not less than 3, in particular not less than 5, in particular not less than 10, in particular not less than 20, in particular not less than 50.

17. Tool according to one of the preceding claims, wherein the tool head (44) has a diameter of at least 5 mm, in particular of at least 10 mm, in particular of at least 15 mm.

18. Tool system (30) for, in particular, machining a workpiece (20), in particular a system for deep drilling, comprising a tool (40) according to one of the preceding claims; an optical transmitter (71) which is configured to couple optical measuring radiation (51) via the first shaft end (42) of the tool (40) and to transmit it to the optical measuring surface (60); an optical receiver (72) which 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).

19. Tool system according to claim 18, wherein the tool system (30) further comprises an evaluation device (88) which is configured to determine a relative position of the first shaft end (42) 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).

20. Tool system according to claim 18 or 19, wherein the tool system (30) has a drive device and / or feed device (11) for the tool (40) and a control device (89), wherein the control device is designed to control or regulate the drive device and / or feed device as a function of the measuring radiation (52) detected by the optical receiver (72) and reflected by the measuring surface (60) at the second shaft end (43).

21. Tool system according to one of claims 18 to 20, wherein the optical receiver (72) has a plurality of light-sensitive sensor areas, in particular wherein the optical receiver is a quadrant sensor.

22. Tool system according to one of claims 18 to 21, wherein the optical receiver (72) comprises a polarization sensor.

23. Tool system according to one of claims 18 to 22, wherein the optical transmitter (71) and / or optical receiver (72) are arranged in a stationary manner relative to the tool (40), in particular arranged and configured to rotate together with the tool (40) about a longitudinal axis of the shaft (41) during machining of the workpiece (20).

24. Tool system according to one of claims 18 to 23, wherein the optical transmitter (71) and the optical receiver (72) are arranged in a measuring adapter (74) which is arranged between the tool (40) and a drive device and / or feed device (11) for the tool (40).

25. Measuring method (100) for a machining of a workpiece (20), in particular for deep drilling, comprising the steps: Providing a tool system (30) according to one of claims 18 to 24 with a tool (40) according to one of claims 1 to 17 (S101); Coupling optical measuring radiation via the first shaft end (42) and transmitting the optical measuring radiation to the optical measuring surface (60) with the optical transmitter (71) (S102); Receiving the measuring radiation reflected back from the optical measuring surface (60) to the first shaft end (42) with the optical receiver (72) (S103); Determining the relative position of the first shaft end (42) 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) with the evaluation device (88) (S104).

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