Machine tool unit with tool sensor for sensing tool cutting edge load

Abstract

A method for sensing a cutting edge load and a motor-driven machine tool unit, such as a multi-axis rotary head or a motorized spindle, having a stator unit and a rotor unit rotating at least about an axis of rotation, the rotor unit comprising at least one tool receiving unit for receiving a tool, in particular comprising a tool holding device which is adjustable in the length direction of the axis of rotation and to which a tool shank which is releasably securable for securing and holding a tool whose tool head comprises at least one cutting edge, a tool force can be applied, at least one tool sensor being provided for sensing a load on the tool, the at least one tool sensor being implemented as a single cutting edge sensor for sensing a cutting edge load on a single cutting edge, the prior art is at least partially improved. This is achieved in particular in accordance with the invention, since the stator unit comprises at least one cutting edge sensor.

Description

Technical Field

[0001] The present invention relates to a motor-driven machine tool unit according to claim 1, such as a multi-axis rotary head or motor shaft, and to a method for sensing cutting edge load according to claim 11. Background Technology

[0002] For machine tools, there are various interchangeable devices or tools that connect to the machine tool via standardized interfaces. In this case, these tools are connected to the machine tool spindle or motor spindle via separable tapered connectors, and so-called chucks are opened or closed by axial movement, so that the axial force required to securely fix the tool can be transmitted to the tool, or can be released again later.

[0003] Tools used for machining should only be used before they reach their typical wear limit, which is usually specified by the manufacturer. If the tools used are excessively worn and exceed the wear limit, the machining results will generally no longer meet the requirements. To avoid generating a lot of scrap during manufacturing, it is desirable to be able to inspect and track tool condition in situ (e.g., during manufacturing), rather than relying on quality control measures such as manufacturing tolerances, dimensional accuracy, or edge sharpness, to determine whether received workpieces are no longer being maintained due to tool wear.

[0004] According to EP 2 924 526 A1 and WO 2019 / 101 617 A1, this is accomplished by means of a measuring device, in addition to the machine tool, equipped with a tool aging adapter containing a corresponding measuring sensor. On this measuring device, the tool load bending moment is sensed based on components oriented in two linearly independent directions perpendicular to the axis of rotation and stationary relative to the rotating tool, and thus considered as components of a pair of values ​​sensed in the corresponding coordinate system. In the case of this known proposal, the image is obtained, particularly regarding the symmetry of the sensing and its disturbance, where disturbances to the symmetry are sensed as deviations from a specified state, and as wear on at least one cutting edge of a multi-edge tool. This system has been provided by Pro-Micron GmbH & Co. KG under the brand name "SPIKE".

[0005] In this context, the specific indication is a pair of values ​​for the bending moment components sensed by a strain gauge, realized from two linearly independent directions perpendicular to the tool's axis of rotation. The purpose is to identify the tool's condition and the tool's problems for each individual cutting edge, and to indicate this through wear characteristic values.

[0006] Based on the wear on a single cutting edge, the worn tool should be replaced at an early stage to specifically avoid breakage of the cutting edge / drill bit, or to minimize machining inaccuracies / or product / workpiece scrap.

[0007] However, the main drawback of this prior system was the significant assembly and economic costs involved, especially the need for additional, individual adapters and additional evaluation devices or computers. In this case, measuring electronics or sensors were integrated into each individual tool holder of the machine tool, which increased costs and effort. Therefore, the effectiveness of spontaneously using another tool holder could only reach a limited extent if there was a corresponding need.

[0008] In this system, sensor data / signals are wirelessly transmitted from the tool adapter to the evaluation device or computer. This is not only complex but also susceptible to interference, especially under the "harsh" conditions of industrial machining, where numerous sources of interference are typically present in the production hall.

[0009] Furthermore, the effective length between the force (cutting force) and the so-called HSK (hollow short taper) planar surface increases with the system or via an adapter. This results in a considerably large bearing load, which is also disadvantageous, as the system correspondingly increases the leverage ratio.

[0010] In addition, a "spike inspindle" variant is now also available. This uses a special tapered sleeve that is essentially placed in front of the spindle. Although this variant is tool-independent, the aforementioned technical and economic drawbacks largely remain.

[0011] In any case, in the case of so-called "deep hole drilling," very early and accurate identification of potential dangerous wear or changes in individual cutting edges is crucial to avoid drill bit breakage and jamming within the workpiece. This can potentially be further improved. Summary of the Invention

[0012] Objectives and advantages of the present invention

[0013] The object of this invention is to provide an electric motor driven machine tool unit and / or a method for sensing cutting edge load, wherein assembly difficulty and economic effort are minimized as much as possible compared with existing technologies and / or higher requirements, particularly regarding the accuracy and / or safety of machining and / or the early identification of harmful wear of individual cutting edges.

[0014] This objective is achieved by the features of claims 1 and 11, respectively, from the aforementioned machine tool unit and the method of the aforementioned type. Advantageous embodiments and further developments of the invention are made possible by the measures set forth in the dependent claims.

[0015] Therefore, the machine tool unit according to the invention is characterized in that the stator unit includes at least a single cutting edge sensor.

[0016] Because of the single cutting edge sensor arranged on / in the stator unit according to the present invention, it is possible to configure an additional single tool adapter and an additional evaluation device with a display unit / screen. Furthermore, as in some prior art cases, it is not necessary to split the rotor shaft to integrate the single cutting edge sensor. Therefore, assembly and economic costs are significantly reduced compared to the prior art.

[0017] Within the scope of this invention, a single cutting edge sensor enables the sensing of cutting edge load on a single cutting edge, especially particularly when the tool head has multiple cutting edges rather than just one. Currently, for example, commercially available drills typically comprise two single cutting edges, and in many cases, commercially available end mills comprise four or even more single cutting edges. Within this invention, the cutting edge and the so-called cutting insert or cutting head can both be understood as the cutting edge. In the case of commercially available tools, the cutting insert or cutting head is typically made of hard metal, cermet, polycrystalline cubic boron nitride (CBN), polycrystalline diamond (PCD), or cutting ceramic, or less often of HSS, HSSE / HSS-PM, and serves as a material carrier for cutting, for example, metals, plastics, or wood.

[0018] Therefore, according to the present invention, changes such as wear or deterioration of a single cutting edge and / or multiple cutting edges, and / or partial breakage / fracture and / or blockage / wedging of a single cutting edge and / or multiple cutting edges, can be advantageously sensed and analyzed / assessed. If necessary, advantageous machine response can also be achieved, particularly by means of advantageous electrical / electronic monitoring units, such as alarms or signals and / or displayed outputs, and / or slowing down and / or stopping of processing or operation.

[0019] According to the present invention, the effective length between the applied force / cutting force and the so-called HSK planar surface is not "extended". Therefore, compared to the prior art described above, this results in a considerably smaller bearing load due to the significantly reduced lever ratio relative to previously known systems. This has a positive impact on the bearing's size / load.

[0020] Furthermore, according to the present invention, particularly through the shorter extension length of the tool, operation / process is generally positively affected. The tool has greater rigidity, resulting in less tool deflection during operation / processing compared to the prior art. The chatter effect is also positively affected. Due to the shorter tool length, the tool only begins to vibrate / chatter under higher loads, which improves machining accuracy.

[0021] Basically, according to the present invention, thanks to the tool adapter, commercially available tools and tool holders can be used without conversion or modification. Furthermore, the bearings (e.g., motor spindles, etc.) of the machine tool unit according to the present invention typically do not now need to be / cannot be changed, which also reduces costs and effort.

[0022] Therefore, the sensor system according to the invention can be advantageously integrated into the machine tool unit or motor spindle. Thus, it is unnecessary to integrate the measuring electronics into each tool holder / adapter, or into multiple tool holders / adapters, and / or into each tool for use in the machine tool unit. Furthermore, advantageously, each machine unit or each motor shaft requires / installs or assembles the sensor system or a single cutting edge sensor and / or electronics only once. Therefore, according to the invention, cost and expense are very low.

[0023] Preferably, the machine monitoring unit and / or machine display unit includes a processing or evaluation / representation or sensor evaluation unit or sensor display unit for evaluating and / or preparing and / or displaying / representing (advantageously prepared) sensor signals / sensor data. Therefore, assembly and economic costs are also significantly reduced compared to the prior art. Integration of sensor signals / data into the processing of the (always present) machine control system or machine monitoring unit can also be better achieved, particularly faster data processing, because there is no "introduction" of a separate evaluation device (i.e., usually also from another manufacturer), but rather, direct processing via / through the machine's control system or electrical / electronic monitoring system. This is highly advantageous, especially in cases of very short reaction times, such as before a pending breakage of the cutting edge (detected by the sensor) or in the case of sudden, unpredictable jamming of chips on a cutting edge of the tool.

[0024] Advantageously, the single-cutting-edge sensor is implemented as a single-cutting-edge force sensor for sensing the force applied to a single cutting edge. Numerous tests have shown that sensing the force acting on or applied to a single cutting edge is substantially more direct and advantageous than sensing the bending moment on / at the tool or tool holder. In particular, axial loads or applied forces, such as those frequently occurring on / present of tools used in large quantities (i.e., drills, end mills, etc.), can be sensed and evaluated better / more accurately than sensed bending moments. The bending moment of a tool or tool holder is usually generated primarily by the action of radial loads or forces; however, these bending moments only exist indirectly in the case of drilling.

[0025] According to the invention, the advantageous measurement of force enables particularly accurate results, namely, particularly good sensing of the load or force applied to a single cutting edge, which can be further used or processed, for example, by means of an advantageous electronic monitoring unit.

[0026] In an advantageous variation of the invention, when viewed in the axial direction, a single cutting edge sensor is arranged at least partially horizontally to the tool clamping device and / or tool holding unit. Thus, as viewed in the direction of the axis of rotation, the single cutting edge sensor is arranged either adjacent to the tool clamping device / chuck / clamping segment and / or tool receiving unit, or in the region of the tool clamping device / chuck / clamping segment and / or tool receiving unit, or in a radial direction with a radius larger than the tool clamping device / chuck / clamping segment and / or tool receiving unit. This allows displacement and / or material deformation of the mating support / stop, or spindle or tool receiving unit / tool ​​clamping device, caused by applying a load / force to the single cutting edge / edge, to be advantageously sensed.

[0027] In a particular further development of the invention, the individual cutting edge sensor is implemented as a displacement sensor and / or deformation sensor for sensing the displacement and / or deformation of at least a portion of the rotor unit and / or tool receiving unit caused by the cutting edge load on the individual cutting edge. For example, it is advantageous to use / sensor or assess the displacement and / or material deformation of a (very small) shaft caused by the load on the individual cutting edge, particularly a few micrometers, and preferably, to enable control / monitoring of the machining process during operation or chip removal. This means, advantageously, the assessment / realization of applied forces and / or wear and / or vibration along the axis of rotation or in the axial path. Therefore, entirely new possibilities for monitoring the machining process for each individual cutting edge are realized, thereby achieving significantly higher accuracy and safety in machining.

[0028] Preferably, the single cutting edge sensor is implemented as a non-contact operating sensor for non-contact sensing of the cutting edge load on a single cutting edge and / or the displacement of the shaft caused by the cutting edge or the force on the cutting edge. Therefore, it is possible to transmit sensor signals or measurement data from a rotating rotor unit or a rotating adapter fixedly connected to the tool to a static evaluation unit and / or a static stator unit. Compared to the prior art described above, this further reduces assembly difficulty and economic costs. Moreover, it effectively prevents wear of the corresponding (contact or friction) components of the sensor system and results in a longer service life.

[0029] Therefore, according to the invention, the relay of data / signals or information can advantageously (completely) be achieved via cables or by means of (electrical) cables / lines, particularly in the front of the machine tool unit or in the motor spindle, enabling sensing or "information processing." During machining, sometimes the rotational speed is very high, and therefore the time intervals are very short, etc., sensitive data / signals from the various cutting edges of the tool, or their minimum / minimum changes, are substantially less susceptible to interference, distortion, or errors in transmission when relayed or transmitted via cables / lines.

[0030] Advantageously, the individual cutting edge sensor is implemented as a proximity sensor for sensing the distance between the rotor unit / proximity sensor and at least a portion of the rotor unit and / or tool receiving unit, said distance being changeable by the cutting edge load on the individual cutting edge. In this case, it is advantageous to sense / measure the distance between a movably mounted component / shaft of the rotor unit and the stator or stator component / housing, and thus the action of force, especially the force from the individual cutting edges, can be detected. In this way, especially because various environmental vibrations can be filtered out by an advantageous measurement arrangement (e.g., relative measurement), high-frequency (minimum) changes in force can be detected more accurately. Measurement points fixed on bearings, typically on the front side of the motor spindle, are highly suitable.

[0031] Therefore, displacement and / or material deformation caused by tooling or cutting / machining can be advantageously sensed, particularly displacement and / or material deformation of rotor components, i.e., decreasing or increasing the gap or distance between rotor and stator units. According to the invention, this distance change can be used to indirectly sense individual cutting edges of the tool, or their changes and / or states, such as wear / debris / part breakage, chip blockage / wedging, etc.

[0032] In an advantageous embodiment of the invention, a single cutting edge sensor is implemented as an inductive sensor, particularly an eddy current sensor and / or an optical and / or magnetic sensor / Hall sensor and / or an ultrasonic sensor and / or a radar sensor. According to the invention, corresponding sensors that are already commercially available and proven can be acquired, used, or applied. This improves the cost-effectiveness and reliability of sensing.

[0033] Specifically, implementing a single cutting edge sensor as a non-contact and / or contactless sensor ensures particularly advantageous sensing of displacement and / or deformation and its generation, and, where necessary, the relay of advantageous sensor signals or measurement data. In this case, changes / reductions in distance / gap between the rotor and stator units can be advantageously sensed. Particularly advantageous for this purpose are inductive sensors with at least one measuring coil, magnetic sensors with magnetic or magnetizable materials / elements, and / or optical sensors with light emitters and / or receivers and / or reflectors, such as deformed portions / surfaces of the rotor unit / tool ​​holder / spindle. For example, visible light, lasers, UV or infrared light, and / or optical interferometers can be used to sense, for example, changes in distance.

[0034] Preferably, the single cutting edge sensor is implemented as an axial sensor having at least one sensing area aligned along the length of the axis of rotation. It has been shown that axial loads applied to the tool cutting edge or cutting edge can cause (slight) axial displacement and / or deformation of the rotor / spindle. Compression of the axial alignment of the mating supports / stops produced by machining, or the rotor shaft or spindle and / or its components, can be sensed by means of an advantageous axial sensor. Depending on the arrangement / design of the axial sensor, distances / clearances that can be increased or decreased can be sensed.

[0035] In an advantageous variation, a single cutting edge sensor is implemented as a radial sensor having at least one sensing area, which is perpendicularly aligned with respect to the longitudinal direction of the axis of rotation. In this way, advantageously, displacement and / or radial deformation of the rotor unit components and / or the mating supports / stops of the spindle produced by machining can be sensed by means of an advantageous radial sensor.

[0036] Typically, using a single cutting edge sensor according to the invention, in cases of damage and / or breakage and / or scaling, or harmful changes to a single or multiple cutting edges, may already be advantageous. Thus, for example, in the case of breakage of one of (four / six) cutting edges during machining (i.e., during rotary operation), or during rotation of the rotor unit / spindle / motor spindle, according to the invention, this single sensor may already sense a change / damage to one / each individual cutting edge. This is because, according to the invention, changes / reductions or absence of displacement and / or deformation at the previous and / or normal / standardized detection / area location are detectable during / after a full rotation of the shaft / rotor unit.

[0037] Furthermore, for example, by means of a single cutting edge sensor according to the invention, the accumulation of debris on only one of a preferred plurality of cutting edges can be sensed even at the start of tool machining or chip removal. This is because, for example, debris or dust particles that have been wedged between the single cutting edge and the workpiece can cause displacement and / or deformation, particularly larger or more pronounced spatial displacement and / or material deformation at that particular location on the rotor unit, a change that is detectable during startup / start-up or after a full rotation of the rotor unit / spindle. According to the invention, this can be further sensed and processed / used, for example, for monitoring or controlling and / or braking / stopping the rotor unit or spindle / motor spindle.

[0038] Typically, beneficial signaling of changes in sensed displacement and / or deformation—that is, the deviation between the sensed actual position and / or actual deformation and the (desired) specified position and / or specified deformation—is helpful to the machine tool operator. Preferably, signal posts and / or display / screen indications are activated to notify the operator of changes or damage, to locate errors or alterations, and to eliminate them. This achieves significant improvements in quality assurance or avoids scrap.

[0039] With the help of a favorable rotary encoder, for example, individual cutting edges / cutting segments can be identified and, if necessary, displayed / identified.

[0040] Alternatively or in combination, the (graphical) representation / presentation can be achieved in a coordinate system, particularly a Cartesian or polar coordinate system. If desired, the tool used or one or more cutting edges can be virtually displayed on an indicator or screen / monitor, and in this case, advantageously, the sensing / detected changes / damage to the cutting edge / location or position, such as wear and / or breakage or breakage risk of the cutting edge or part of the cutting edge, and / or breakage risk of stuck debris on the cutting edge, etc., can be displayed.

[0041] Preferably, the stop / braking or halt of the rotor unit can be generated (especially even before tool breakage, etc.) after (immediately or directly) sensing a change in deformation and / or a deviation between the sensed actual position and / or the actual deformation and (stored / defined) a specified position and / or specified deformation, so that inaccuracies or damage are impossible during the machining of the workpiece, especially in terms of precision.

[0042] Advantageously, at least two or more individual cutting edge sensors are arranged in the circumferential direction, particularly at mutually different angular positions around the axis of rotation and / or symmetrically arranged around the axis of rotation. In this way, displacements and / or deformations, as well as oscillations of the rotating rotor unit (especially the spindle or motor spindle), can be advantageously sensed. Preferably (immediately or directly) after / during the sensing of changes in distance or oscillation of the rotating rotor unit (especially the spindle or motor spindle), and / or the deviation of the sensed actual oscillation from (stored / defined) a specified oscillation, the stopping / braking or halting of the rotor unit can be generated by means of an electrical monitoring or control unit, thereby avoiding inaccuracies or damage, particularly in terms of precision, during workpiece machining.

[0043] The present invention advantageously relates to sensing the elastic displacement and / or deformation of components of a machining spindle or motor spindle during motion, which is caused by a force or load applied to a single cutting edge of the tool. In this case, it is advantageous that the displacement and / or deformation caused by the cutting force can be measured during / at operation, and thus inferences can be drawn regarding the safe and precise machining of the workpiece relative to each individual cutting edge.

[0044] In principle, reference measurements can be performed at any time. Performing measurements at regular intervals can also be useful, and if necessary, a nearby dataset can be used as a reference measurement. In the absence of wear or changes in the cutting edge, especially in databases or storage media, reference measurements in a new or clean state help eliminate the need for additional effort to maintain or store the actual state. However, new records of reference measurements can be used to check if distance values ​​have changed, typically due to routine operation, wear, etc.

[0045] Contrary to technological bias, it is not absolutely necessary to use two sensors to measure the state, for example, at different angular locations in a plane perpendicular to the axis of rotation, in order to determine the deflection at different angular locations and to be able to use the data for evaluation. Instead, measurements at a single angular location (e.g., by a single sensor) are sufficient, and comparisons with specific values ​​are advantageously taken into account.

[0046] Preferably, the rotor unit and / or tool receiving unit includes at least one marking and / or measuring element, particularly a measuring ring. For example, the rotor unit may have additional elements specifically for measuring or sensing distances relative to the measurement being performed or relative to a sensor or its sensor head.

[0047] Depending on the type of sensor / head, the measuring ring can therefore possess properties advantageous for measurement, such as being made of a suitable material or having measurement markings. Due to the size of the measuring ring, a lever-like effect can also be added, i.e., small deformations have a greater impact over a larger distance, enabling higher measurement sensitivity and accuracy. In the case of inductive sensors, particularly in specific eddy current sensors, it may be advantageous if the material used for the measuring ring, while conductive, does not possess ferromagnetic properties, but only voltage induction needs to be considered. The measuring ring can be made, for example, of lightweight aluminum with a passivated oxide layer formed on its surface, which is also corrosion-resistant.

[0048] In exemplary embodiments of the invention, the marker and / or measuring ring can be placed, for example, on the spindle head. It is also conceivable that the spindle head and the measuring ring or marker will be implemented as a single piece, i.e., fixedly connected to each other or made of the same material. For example, the latter embodiment is suitable for manufacturing if the spindle head and the measuring ring or marker can be made of the same material. Furthermore, the measuring ring offers the advantage that the reference marker can be applied in almost any manner without impairing the function of the rotor unit, thereby enabling improved measurement quality.

[0049] If a sequence of measurements is recorded and compared with, for example, another sequence of measurements, the phase relationship between the two sequences or a series of measurements can be advantageously known. At least the allocation of measurements to be compared should be implemented in a manner that maintains a constant phase relationship, so that the evaluation can provide meaningful results. It is generally advantageous if a constant time interval exists between two consecutive measurements in the corresponding sequence, and / or the rotor unit has rotated through the same angle, so that the angular difference between the positions where the measurements were taken can be tracked based on the measurements. Advantageously, in a further development of the invention, an initial point can be set in the recording of the distance value sequence. For this purpose, the measuring ring advantageously has reference markings, for example in the form of grooves, holes, other recesses, or heights. In principle, optical markings are also conceivable.

[0050] According to the invention, distance values ​​are recorded by only one sensor head. For example, in the case of recesses or elevations, a reference marker can alter the distance in such a way that the inspection device identifies it as an initial point. However, it is also conceivable to sense the initial point using other sensing devices, such as optical markers. This can be sensed by a single trigger sensor; however, this single trigger sensor does not provide a distance value for evaluation, i.e., it does not represent an additional sensor head for distance measurement in the sense of the invention.

[0051] The advantage of optical markings is that they can be correlated with minor imbalances on rapidly rotating parts. Additionally, they can more clearly distinguish between deviations caused by axial runout errors and differences if the reference mark cannot be interpreted as the initial point of deformation, such as in cases with grooves or protrusions.

[0052] In principle, it is conceivable that the principle for sensing the mark or measuring element / ring can be used with various types of sensors or sensor heads, and can be determined by the distance from the rotor unit and / or the measuring ring or mark. Preferably, a non-contact distance sensor can also be used here, since according to the invention, the sensor or sensor head is mounted on the stator unit and the distance from a portion of the rotor unit is fixed. And preferably, an eddy current sensor is used here, particularly since eddy current sensors are generally insensitive to oil, water, or non-metallic dust, which must of course be expected during machine tool operation. An eddy current sensor can be considered an inductive sensor. However, exemplary embodiments with capacitive or optical sensors for sensing the mark or measuring ring are also conceivable.

[0053] Advantageously, in another embodiment of the invention using an eddy current sensor, the measuring ring can be made of a non-ferromagnetic material, such as a paramagnetic material, thereby also enabling improved measurement accuracy, since ferromagnetic materials are always subject to the influence of the dominant magnetic field in the machine tool. Therefore, if a ferromagnetic material has been exposed to a magnetic field, it will retain some remanence even if the external field is no longer present. If the magnetization of the measuring ring or a portion of the rotor unit at a defined distance can affect the measurement, ferromagnetic materials should be avoided, and, for example, an eddy current sensor should be selected.

[0054] For evaluation purposes, it is generally advantageous to determine the difference between the current measurement and the corresponding reference value so that deviations can be identified and assessed. Since the time series of distance values ​​relative to the rotating rotor unit is recorded, the measurement signal can be decomposed into a continuous spectrum via Fourier transform. Therefore, geometric deviations, i.e., the distance values ​​that deviate, are represented according to their frequency of occurrence. If larger, or particularly individually occurring, geometric deviations are observed in the spectrum, it is generally assumed that axial runout error is present.

[0055] According to the present invention, the single cutting edge is characterized by the fact that there is essentially no time loss for actual measurement, and the measurement can be performed without limitation, for example, after each tool or tool holder change. In this way, it can also be more easily integrated into the machining process, especially since there is no need to specifically provide a time period during which the measurement or inspection process can or must be performed.

[0056] Typically, the rotor unit, rotating relative to the stator unit, is part of the motor-spindle drive. The actual cutting tool (milling cutter, drill bit, etc.) is held or clamped in a tool holder, which is then arranged in a tool holder, considered part of the spindle head of the rotor unit. For this purpose, the tool holder has mounting elements for the tool holder. A clamping force is applied to the tool holder and adjusted along the length of the axis of rotation. In this case, a portion of the clamping device can be drawn into a conical receiver, so that the tool holder or tool can then be clamped, particularly by a radially acting force. Removal of the clamping force causes the clamped tool to be released again, and it can be removed or changed from the machine tool.

[0057] Typically, the actual sensor is housed in what is called a sensor head; the sensor measures its distance to the rotor unit, and the sensor itself is correspondingly arranged in the stator unit. The sensor data is processed or evaluated by electronic units or evaluation electronics, which may be computer-controlled.

[0058] At least one sensor head is substantially arranged on the stator unit at a fixed position in the area of ​​the tool holder, and can measure / sensor the end face and / or both laterally of the rotating spindle head.

[0059] However, in principle, the sensor or sensor head can also be arranged in a variable position. For example, as a rule, debris stuck between the tool and the workpiece causes the tool to no longer run precisely centered / straight around the axis of rotation, or the tool holder to deform slightly (and also elastically), and the radial true running remains unchanged, the axial true running of the tool or tool holder remains unchanged, or it no longer ensures no angular change. As a rule, disturbances in radial true running indicate specific damage to the machining process. Such misalignment and / or deformation typically occur on the lateral and end-face / axial sides, and in principle, can also be detected. On the end face, the distance parallel to the axis of rotation is measured, and the radial distance to the axis of rotation is measured laterally. The displacement of the rotor unit caused by all such misalignment and / or deformation can be determined in such a way.

[0060] In principle, measurements can be taken at an angle of 90° relative to the end face and / or the axis of rotation of the rotor unit, but can also be taken at different angles.

[0061] In the case of machine tools, in particular, there are stringent requirements regarding machining accuracy. During machining, the tool and therefore the cutting edge / cutting blade must be inserted and moved into the tool holder or tool clamping device in a precisely defined manner so that the workpiece to be machined is within specified tolerance limits. Even if the machine tool (especially the tool clamping device) is manufactured to the necessary precision, additional factors exist during the machine's use to prevent radial / axial misalignment or angular errors from occurring. During machine tool operation, for example, debris generated during machining can adhere to or clog the tool, resulting in the tool not rotating in its intended position.

[0062] Because the wear and / or chipping of the cutting edge are sometimes very small, these errors / deviations from (normal) specified conditions are often difficult to determine and occur randomly. However, such axial runout or angular misalignment of the tool can cause the workpiece to be outside the tolerance limits after machining.

[0063] The sensor / head measures a time-dependent or position-dependent sequence of distance values. If the sensor / head records a time-dependent sequence of distance values, this usually occurs simultaneously with the position-dependent sequence because the rotor unit rotates according to the time-dependent sequence, unless one or more complete rotations have always been achieved between the recordings of individual measurements. Typically, not only the variation in the actual axial movement can be determined according to the invention, but also, for example, the angular position in the actual radial movement can be determined. It is also conceivable that if, during machining operations such as milling, the cutting edge position (phase) changes (in a significant way) relative to a favorable mark, such as a reference groove, for example, in the case of recess milling, then the torsional torque can be determined. In this case, the torsion angle can be determined based on the tool length.

[0064] By means of the aforementioned markings at advantageous locations on the rotor unit or on the rotor shaft, even if the rotational speed or angular velocity is unknown, it is possible to clearly detect when the rotor unit completes exactly one rotation using the reference markings. In particular, it is advantageous to exclude a single encoder from the evaluation when determining runout or angular error without considering other sensors. The markings can preferably be detected simultaneously by the sensor / sensor head during the actual measurement process. Therefore, in principle, no further sensors are required for this purpose. However, it is also conceivable that additional sensors could be provided for identifying individual markings, especially if distance measurement is to be independent of marking identification.

[0065] In variations of the invention, there is also the option of using more than one marker, particularly for measuring rings. In this way, even more information can be obtained through measurement, enabling, for example, sensing the direction of rotation, signal direction, or synchronization. To utilize the sensing of the markers to obtain additional information, the markers can also have a specific shape, such as an inclined trapezoid, so that the direction of rotation can be identified from them.

[0066] Since the markers can also be used to sense the current rotational speed or rate of the rotor unit, the method according to the invention has a significant impact on the accuracy of error measurement. However, the measurement initially needs to be performed at a constant rotational speed so that the measured values ​​can be compared and correlated with each other accordingly. The invention aims to save additional time, for example, enabling meaningful measurements to be performed during the (positive or negative) acceleration of the rotor unit.

[0067] Therefore, the first or second distance value sequence can typically be recorded outside the marked area. However, since these measurements are performed during the acceleration phase of the rotor unit's rotation, these distance values ​​cannot initially be easily correlated, as time-correlated sampling is typically performed at a predefined clock rate (i.e., at equal time intervals), but the accelerated rotor unit rotates to different degrees between two consecutive clock pulses, so the positions no longer match, especially in the case of at least two measurement sequences. Machining is typically performed at a constant rotational speed / rate, but it can also be performed during the acceleration phase (described earlier).

[0068] The path-time relationship or angle-time relationship is described as follows:

[0069] s(t) = 0.5at 2 + v0t,

[0070] Where s(t) is the time-dependent distance traveled in time span t, or the angular range scanned in time span t, a is the acceleration, and v0 is the current rotational speed / rate at the beginning of time span t.

[0071] According to the present invention, a sequence of measurement values ​​can be recorded. In this case, the distance between the sensor / head attached to the stator unit and the rotor unit is determined, and it is measured whether this distance changes as the rotor unit rotates. For the sequences to be comparable to each other, or for the data to be evaluated (e.g., for the sequences to be subtracted), the corresponding positions must be assignable to the distance values. However, time is typically also measured during the recording of the distance values.

[0072] The rotor unit initially accelerates during machine startup. This acceleration can be achieved in a substantially uniform manner, i.e., a is essentially constant. However, in principle, particularly during the startup of the rotor unit, there are also non-constant acceleration phases.

[0073] However, at the start of the startup process, acceleration is typically not constant over a certain period of time. The rotational speed as a function of time curves slightly to the left in this range, a phenomenon known as the S-curve, meaning the rotor unit starts at a slower speed, causing the startup to proceed in an uneven manner. This is also called shock limiting. Therefore, it is advantageous to measure acceleration within a range of approximately constant acceleration, rather than from a stationary state.

[0074] For each sequence, a set of sequence vectors can be formed accordingly, the set of sequence vectors including:

[0075] - The measured distance value;

[0076] -Time information related to the time point of distance measurement; and

[0077] - Rotational speed / rate value, the so-called current rotational speed / rate; if the rotor unit is accelerated and the rotational speed / rate is measured over a period of time, the same associated current rotational speed / rate value will usually also correspond to at least two sequence vectors.

[0078] According to the present invention, scaling is mathematically achieved under the condition that, in the case of two measurements that follow each other rapidly and continuously, the quadratic component of the equation of motion, i.e., the angular component attributable to acceleration, can be ignored.

[0079] Linearization is possible if the time span between the measurements of two distance values ​​is chosen to be just small enough. Thus, the current rotational speed / rate is assigned to the first and second sequences, even if one of the measurements is performed later and the actual rotational speed / rate value differs from the assigned current value. Since terms involving acceleration and the square of time are negligible, linear scaling of the rotational speed or rate is possible under given mathematical conditions. Therefore, measurements can also be performed, for example, during the machine's startup phase. A waiting period for machine startup is always necessary, whether short or long, because predefined conditions for machining operations (such as tool rotational speed) are typically not yet met during this period. However, it is particularly advantageous if the presence of, for example, axial runout, radial runout, or angular error has been determined during the rotor unit's startup, as the process can be interrupted if necessary, and tool cleaning or repositioning can be performed before machining. For example, in the case of tool change, it is generally expected that a change in axial true runout, radial true runout, or angular position will occur. If this deviation becomes so large that it exceeds a (possibly predefined) threshold, an error exists.

[0080] Therefore, production time can also be increased, which is directly related to cost advantages. Particularly advantageous is the uniform acceleration of the rotor unit throughout the entire recording period of the measurements. This again simplifies the evaluation, which consists only of the approximation of the acceleration portion or angular-time diagram from the path, neglecting the acceleration portion or angular-time diagram. This is possible because the measurements of the continuous measurements are recorded one after another in very short intervals, and therefore their time intervals or angular distances are very small; that is, the acceleration term, as a quadratic function of time in the case of uniform acceleration, becomes correspondingly negligible.

[0081] Therefore, in an exemplary embodiment of the invention, scaling is performed by determining the time interval between the current rotational speed / rate at different time points and the measurement of rotational speed or rate, with acceleration taken into account. Ignoring the acceleration term results in a path-time diagram or angular-time diagram comprising a linear term that depends linearly on time, and where the rotational speed / rate (path speed or angular velocity) (rather than acceleration) is treated as a constant. According to embodiments of the invention, the current rotational speed / rate can be determined in various ways. For example, it may be convenient to determine the current rotational speed or rate based on the marker by measuring the time between two consecutive detections of the marker by the sensor / head. Such measurements are more accurate if the marker constitutes only a relatively narrow portion of the angular segment, ideally a stamping mark. Furthermore, it is conceivable to implement the marker in a manner that it occupies a predefined arcuate portion and to determine the time it takes for the marker extending over a known angular segment to pass through the sensor head.

[0082] For example, if a single marker is provided, meaning that the marker passes precisely through the sensor head once per rotation, then a single measurement of rotational speed or rate is taken, and this current rotational speed / rate is determined inaccurately by the rate of change within a rotation. Differences caused by acceleration during that time interval of rotation are then disregarded. Conversely, when the marker constitutes only a small portion of the entire 360-degree rotation angle, and for example, when the front of the marker reaches the region of the sensor head in the direction of rotation, and the rear of the marker subsequently passes through the sensor head in the direction of rotation, the measurement is correspondingly more accurate.

[0083] For example, in one embodiment of the invention, the markings can be implemented as grooves, such as in a measuring ring attached to the rotor unit, particularly for this purpose, such that the regions outside and inside the groove have different distance values. The lateral surfaces occurring at the edges of the groove are then measured, and the distance values ​​measured by the sensor head are measured accordingly. The groove can, in principle, have lateral surfaces extending perpendicularly to or radially to the axis of rotation or to an inclined side.

[0084] Therefore, progress can be tracked via sensors / head while measuring distance values. Depending on the current angular velocity or path velocity, the occurrence of flanks can be observed at shorter or longer time intervals. Specifically, in the case of high rotational speeds, a linearized approximation can be performed in such a way that, for example, measurements of the first or second time-dependent and / or position-dependent sequence of measurements are performed within one rotation of the rotor unit. In this case, it is assumed that the rotational speed or rate remains constant within the rotation. This approximation is particularly susceptible to small errors, especially in the case of high rotational speeds, such as those occurring with machine tools. Specifically, at the end of the start-up phase, a higher angular velocity can be expected, making the estimated measurements taken within this range more accurate than those taken at the beginning of the start-up phase.

[0085] Detecting the edge of a marker covering a specific angular segment means that the marker is, in a sense, divided into sub-markers, so that, for example, when a marker enters and then leaves the area of ​​the sensor head, the marker can be identified by the sensor / head. Therefore, for example, when a marker enters the area of ​​the sensor head and its first side is sensed by the sensor head, the marker can be measured. In this case, the time interval between the two measurement events of the marker and the same distance value are used. Similarly, when the marker moves out of the area of ​​the sensor head, a time point can be used. In this way, error estimation can be performed because, in this way, for each measurement point, i.e., for two points with the same distance value, the current rotational speed or rate can be determined, but the time interval between these two points can also be measured simultaneously.

[0086] As explained above, the corresponding rotational speed / rate can be determined, i.e., based on the markings extending over a certain angular range or based on the appearance of the same markings after one rotation. In this way, if the acceleration term at points that are continuous in time can be ignored, the error occurring during the approximate period can be estimated from how the velocity changes over time.

[0087] In this way, it is also advantageous to determine how precisely the method works and to adjust it accordingly if necessary. In an advantageous embodiment of the invention, a time- or position-related sequence of distance values ​​can be used as a reference measurement. For example, it is conceivable to appropriately measure a new machine tool, a new tool holder, or a new tool, where chips have not yet been processed by machining operations, and to record the first sequence of measurements as a reference. It is also conceivable to run the rotor unit with a clean tool holder after a cleaning operation to generate the corresponding reference measurements. Thus, any deviation from the reference measurement can be determined, and then it can be evaluated whether the deviation has the magnitude of radial runout error, variation in axial actual run, or angular error, and therefore variation in one of the individual cutting edges. In this way, machining accuracy can be significantly improved. Measurements relative to the reference measurement constitute a comparative measurement with respect to the running condition.

[0088] The force signal can also be used to infer / sensor possible cutting conditions. According to the invention, tools can be replaced based on actual wear, rather than empirically based on a lifespan typically indicated / specified by the manufacturer. This saves on tool blank costs and maintenance of tools such as spindles, which can be used for longer periods without overloading due to worn tools.

[0089] In the case of a sequence of distance values, in particular, a marker can be set as the initial point so that distance values ​​can be assigned to sequences distinct from each other, especially in the case of difference and / or Fourier transform. To this extent, reference measurements are advantageous because, as a result of the measurement itself, it can be determined when a complete rotation has been performed. This is particularly advantageous when the method is performed without any value related to the current speed or velocity provided to the electronic evaluation system by other sensors or machine control, but rather the determination is made solely by the values ​​of the sensor head or sensor head.

[0090] In principle, each distance distribution can be fully captured during a single rotation. However, rotational speeds are very high, and measurements can often be advantageously achieved at relatively high sampling rates. For example, if there are axial runout or angular errors due to stuck debris and / or due to slightly worn / broken tools or cutting edges, the periodically occurring deviations will be deterministic and assignable to individual cutting edges. To enable this to be evaluated / processed or implemented advantageously, particularly to simplify evaluation, especially to achieve, for example, a Fourier transform of the signal, is performed as a Discrete Fourier Transform, preferably as an FFT or DFT. For this purpose, the values ​​of the first and second sequences can be subtracted from each other, in which case the positions of the distance measurements must be matched for this purpose. However, this subtraction can also be performed after the Fourier transform of the corresponding sequences. Ideally, all distance values ​​will be identical, such that there is no variation in the axial real run compared to the reference measurement, and no damage to the radial real run or change in angular position. However, due to static and systematic errors, in a single measurement, even without changes in the actual axial movement, the change in angular position, or the radial runout error, it cannot be expected that the sensor / head will always accurately measure the same distance value.

[0091] If the distance values ​​are irregular, particularly singularities, they can be determined accordingly because they are detected periodically, and therefore can also be associated with frequencies that can be determined as a result of a Fourier transform. It is also conceivable that the average of time-dependent or location-dependent sequences can be performed, with subsequent differences between the averages.

[0092] Depending on the type of error present (axial runout error with local displacement and / or deformation, or angular error with uniform distance variation), this can also lead to an identification pattern. If the identification pattern is known, it provides information about the type of error, for example, whether there is breakage and / or debris jamming, etc. The use of neural networks is also possible in this regard. This measurement advantageously allows not only the occurrence of errors to be identified, but also a more detailed determination of what the errors actually consist of, making it ultimately possible to remedy the errors, for example, by selectively replacing damaged cutting edges or so-called cutting inserts. Therefore, machine downtime can be significantly reduced. In the evaluation sequence, for example, corresponding changes in the measurement signal can be searched, i.e., time-related or position-related distance values ​​used to change.

[0093] However, it must be considered that each measurement is also subject to error in principle. The more accurate the measurement and the higher the sampling rate of the measurement, the more it is expected that, even with sufficient axial real-run, the same distance value will not always be measured in a single rotation. Therefore, it is advantageous to be able to estimate tolerances. In particular, a threshold can be defined beyond which is assumed to be present, either as a critical wear and / or wedge-shaped debris, or as another error leading to a deviation from axial or radial real-run, or as an angular error that must actually be corrected. In this respect, it is advantageous to compare such variations in measurement with predetermined thresholds.

[0094] In exemplary embodiments of the invention, particularly in the Fourier transform of the frequency value corresponding to the number of rotor revolutions per unit time, the difference of the distance can be compared with a threshold in the evaluation sequence. If the threshold is exceeded, axial / radial runout error or angular error is assumed, because, for example, the breakage of a single cutting edge leads to local displacement and / or deformation.

[0095] Furthermore, in embodiments of the invention, changes in the rotor unit or axis of rotation can be determined based on the difference between two in a time-dependent or position-dependent sequence. This displacement / deformation can have effects, for example, causing the tool to contact the workpiece earlier or later than expected, or as provided by the machine control system. This can be identified / sensed and, accordingly, affects machining accuracy. Advantageously, the identification of the initial cut can be achieved.

[0096] In principle, according to the present invention, not only the total force acting can be measured, but also the force of a single cutting edge can be measured, for example, by means of an advantageous eddy current sensor that can be analyzed / measured with such precision / speed.

[0097] In this way, a critical increase in cutting edge force can be identified, and active intervention can be achieved before the cutting edge and / or the tool reach their maximum permissible force and before fracture. Active intervention can then be achieved, for example, by retracting the tool and thereby releasing the cutting edge, and simultaneously flushing the chip path of the tool if necessary.

[0098] Despite preventative measures, tool breakage can occur repeatedly, for example, if debris accidentally weds into the grooves of a milling cutter or drill bit. Even conventional wear detection methods with process reliability cannot predict tool breakage. This has been particularly evident in the case of deep hole drilling, even at very advanced stages of the process, leading to scrap in many cases because, for example, the drill bit cannot be eroded. Deep hole drilling typically involves drilling to a depth greater than seven times the borehole diameter. This invention now provides significant improvements, particularly in the case of deep hole drilling, which has been critical to date, and also to a considerable extent in general drilling or milling operations, where very early and / or rapid identification of corresponding critical states / conditions of the machining process or of the tool and individual cutting edges is possible.

[0099] According to the present invention, a method for sensing the cutting edge load on a single cutting edge of a tool is provided, wherein a tool head having at least one cutting edge, preferably at least two / four cutting edges, a tool and / or a tool holder for holding the tool, particularly a tool clamping device detachably fixed to a tool receiving unit of a rotor unit, is received by a motor-driven machine tool unit, wherein, in particular, the tool clamping device is adjusted and / or arranged in the spindle head and / or tool receiving unit of the rotor unit in the longitudinal direction of the rotation axis, the machine tool unit having a stator unit, the rotor unit being mounted relative to the stator unit to be rotatable about the rotation axis, and at least one tool sensor is used to sense the load on the tool, the tool sensor being implemented for sensing the cutting edge load of a single cutting edge. The method includes the following steps:

[0100] • Arrange a single cutting edge sensor on the stator unit;

[0101] • Provides at least one sensor head for a single cutting edge sensor, used to determine the distance between the stator unit and / or the sensor head and at least a portion of the rotor unit and / or at least a portion of the tool receiving unit / spindle head, the distance being varied by the cutting edge load on the single cutting edge.

[0102] Measure the distance from the rotor unit and / or tool receiving unit / spindle head portion;

[0103] Record at least one time-correlated and / or position-correlated sequence of distances measured by a single cutting edge sensor and / or sensor head, and

[0104] The axial runout and / or radial runout and / or angular variation and / or torsional torque are determined by considering only the time-related and / or position-related sequences of the measured distance and the portion of the rotor unit / tool ​​receiving unit / spindle head rotating relative to a single cutting edge sensor and / or sensor head.

[0105] Preferably, a mark is provided on the rotor unit and / or tool receiving unit / spindle head, and a single cutting edge sensor and / or sensor head senses the mark (N) on the rotor unit during measurement, and the current rotational speed / rate of the rotor unit is sensed based on the mark sensed by the single cutting edge sensor and / or sensor head.

[0106] Preferably, the current rotational speed / rate of the rotor unit is determined based on the marking: a specific angular segment of the rotor unit is marked as a mark during rotation, and the time required for the sensor head to mark the known angular segment is determined to allow the single cutting edge sensor and / or sensor head to pass through, and / or the time between two consecutive detections of the mark by the single cutting edge sensor and / or sensor head is measured.

[0107] Preferably, the groove is used as a marker, such that the areas outside and inside the groove are at different distances.

[0108] Preferably, under ideal / normal cutting conditions, particularly before the first machining operation by the machine tool unit and / or after the cleaning operation, a time-related and / or position-related sequence of distances used as reference measurements is recorded, preferably individually for each tool (50) used.

[0109] Preferably, the markers are used as initial points, and the initial points for evaluation are assigned to the distance sequences so that the distances of different sequences can be assigned to each other, especially in the difference and / or Fourier transform.

[0110] Preferably, the evaluation sequence of values ​​is determined by at least one of the following calculations:

[0111] • The difference between two time-correlated sequences, followed by a Fourier transform of the previously formed first and second time-correlated and / or positional sequences, particularly a discrete Fourier transform of the difference, preferably an FFT and / or a DFT, and / or

[0112] • The Fourier transform of the sequence in each case, particularly the discrete Fourier transform, preferably FFT and / or DFFT, followed by the difference between the time-correlated sequences in the Fourier transform, and / or

[0113] • Calculate the average of time-related and / or location-related sequences, and then calculate the difference between the averages.

[0114] Preferably, the evaluation sequence is searched for deviations exceeding a predefined threshold or at least two deviations, and in the case of exceeding the threshold, a change in the cutting edge is assumed, particularly wear and / or breakage of the cutting edge and / or blockage of the cutting edge / clamp.

[0115] Preferably, in the evaluation sequence, particularly in the case of the frequency value corresponding to the number of revolutions per unit time of the rotor unit, the difference of the distance in the Fourier transform is compared with a threshold, and if the threshold is exceeded, a change in the cutting edge is assumed, particularly wear of the cutting edge and / or breakage and / or blockage of the cutting edge / clamping.

[0116] Preferably, the determination of whether there are changes in the cutting edge, particularly the wear of the cutting edge and / or the breakage of the cutting edge / clamp, is performed by applying artificial intelligence, particularly by inferring errors and / or changes from the sequence through machine learning. Attached Figure Description

[0117] The accompanying drawings illustrate exemplary embodiments of the present invention, specifically showing:

[0118] Figure 1 This is a schematic diagram of the first machine tool unit according to the present invention.

[0119] Figure 2 This is a schematic diagram of a part of an inspection method for checking the clamping state according to the present invention.

[0120] Figure 3 The relationship between rotational speed and time is shown to illustrate the startup of the rotor unit.

[0121] Figure 4 The radially arranged grooves applied to the measuring ring are shown.

[0122] Figure 5 This is a distance-time graph when the groove is detected.

[0123] Figure 6 This is a diagram illustrating the error estimation based on the distance-time plot.

[0124] Figure 7 A schematic cross-sectional detail of a motor spindle with a radial sensor according to the present invention is shown.

[0125] Figure 8 A schematic cross-sectional detail of another motor spindle according to the invention is shown, the motor spindle having an axial sensor.

[0126] Figure 9 It is based on Figure 8 A schematic cross-section of the motor spindle along its rotational axis, the motor spindle having two axial sensors according to the invention.

[0127] Figure 10 The milling tool to be monitored, with four cutting edges, is schematically shown in the top view and perspective view.

[0128] Figure 11 The fabrication process of the groove is illustrated schematically, where interference on the chip has been caused by excessive feed motion.

[0129] Figure 12 A schematic axial deflection of a tool with four cutting edges is shown during one rotation of the drilling process. Detailed Implementation

[0130] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings.

[0131] Figure 1 A schematic diagram of a machine tool unit 1 with a stator unit 2 and a rotor unit 3 is shown. Figure 1 In this case, specifically, the spindle head is considered part of the rotor unit 3. The stator unit 2 has a ring 4, to which the sensor head is attached in the form of an axial sensor 5. The rotor unit 3 includes a measuring ring 6 made of metal, advantageously of a paramagnetic material. The axial sensor 5 is arranged to measure the distance to the end face surface of the rotor unit 3. However, lateral measurements relative to the radial direction of rotation are also conceivable. This surface determining the distance is located on the measuring ring 6. The axial sensor 5 is implemented as an eddy current sensor so that the most accurate measurement can be obtained even with any fouling.

[0132] The sensor head / axial sensor 5 is connected to the electronic unit 7; together they form an inspection device 8, which is connected to the machine control system 9, so that intervention can be made in the control system in case of excessive axial runout error if necessary.

[0133] In a particularly preferred further development, only a sensor head 5 is provided. It is conceivable to use an additional trigger sensor, for example, to identify an optical reference mark on the measurement ring 6; in this case, such a trigger sensor can also be attached, for example, to the sensor ring 4. The mark can also be implemented as a groove, etc. Using such a trigger sensor, only the initial point of the measurement is triggered, making it easier to define the phase relationship between the measured values ​​during evaluation. The trigger sensor is not absolutely necessary, and it is not required in… Figure 1 China further stated.

[0134] The stator unit 2 includes a housing 10 for the sensor ring 4 and a bearing cover 11. A tool clamping device 12 connected to the rotor unit 3 is present. Figure 1 (A conical ring is shown).

[0135] First, in each case, a sequence 20 of reference measurement values ​​is obtained using the new machine tool unit 1, using the available tool 50 (e.g., Figure 10The tool is clamped in a tool holder. This can be done at the factory or at the customer's site. Reference measurements can also be made using the tool 50 or the tool holder; however, this is not necessary, but in some cases it increases the accuracy of the measurement and may facilitate the detection of very small changes in the cutting edge 53 of the tool 50, especially if, for example, a single tool 50 or tool holder will be used. During operation, a new sequence 21 of distance values ​​is subsequently determined for the same tool 50 or tool holder.

[0136] For example, the following procedure can be used to detect changes in the cutting edge or load:

[0137] 1. Spindle startup to nominal rotational speed

[0138] 1.a. Using the general reference as described above, and / or from / by means of electronic / electrical memory, and / or

[0139] 1.b. Reference value recording: In the time domain, the process is only temporarily stored while the machining process is running, and then the process / operation is compared with the reference value, and / or

[0140] 1.c (only) forms a reference FFT (see below), which in some cases is sufficient to identify changes in the spectrum, such as jitter.

[0141] 2.a Then, each rotation is evaluated to identify cutting edge variations with better accuracy, and / or to achieve visualization or display, and / or

[0142] 2.b Recording is performed at fixed intervals, i.e., evaluations are (always) performed at fixed intervals (e.g., every 10 ms), and / or

[0143] 2.c. Evaluation is achieved through AI.

[0144] 3.a Visualization of results, and / or

[0145] 3.b The operation is modified, such as modifying / adjusting the feed rate, and / or

[0146] 3.c Control of operations or processes.

[0147] Therefore, a set of reference measurements can be performed for different tools 50 or tool holders; this operation increases identification accuracy. Since sequences 20, 21 are preferably already recorded at the start of machine tool 1, and therefore during the acceleration of rotor unit 3, the position data of the corresponding distance values ​​must be scaled so that they can be compared with each other. Figure 2 In this context, these values ​​are scaled accordingly for sequences 20 and 21. Figure 2In the middle, difference 22 is formed. Subsequently, frequency analysis 23 of the signal is performed in the form of Fourier transform. Check (method step 24) whether there is a deviation at a certain frequency (e.g., at the rotation frequency of rotor unit 3), or the frequency at which such a change occurs. If these exceed a critical and / or predetermined / stored threshold K (see, for example, Figure 11 If there are interfering variables or disturbances, such as critical wear of cutting edge 53, breakage of cutting edge 53, or deformation of cutting edge 53 (amplitude assessment: method step 25) due to wedge-shaped chips in region A.

[0148] In tandem operations, reference measurements can be performed at very short time intervals, particularly after tool changes, possibly once during the first startup phase, and the single cutting edge check according to the invention can preferably be performed during each / entire machining phase. Figure 3 In the example, rotor unit 3 accelerates during the first 300ms, during which measurements are taken. The S-curve S shows a curve slightly skewed to the left, indicating a slow start to avoid jerky motion of the rotor unit. Linearization is useless in this range because the acceleration is not constant, and approximations by ignoring acceleration components are generally too inaccurate. However, essentially, if no axial runout is detected here, machining can be performed, i.e., tool 50 and tool holder are properly clamped / assembled. Otherwise, braking may be necessary for safety reasons. Starting from approximately 300ms, a constant speed of approximately 4000 rpm is obtained for the machining example.

[0149] Figure 4 A cross-sectional perspective view of rotor unit 3 is shown, which includes a measuring ring 6 having grooves N in the side regions. A magnified view shows edge regions F1 and F2, which can be implemented as side surfaces and can be sensed at a correspondingly high sampling rate. Therefore, for example, the current rotational speed / rate can also be determined by sensing the corresponding side surfaces at the beginning and end of the grooves N using a sensor head.

[0150] Figure 5 Two diagrams are shown illustrating the profile of the measured distance u between the sensor head 5 and the rotor unit 3 when the groove N passes through the sensor head 5 at different speeds in each case, here being 10 times the rotational speed / rate. In the regions of sides F1 and F2, the time dependence of the distance u is sloping because the groove N in regions F1 and F2 also has a sloping path. Therefore, this profile is compressed in time at a higher rotational speed / rate 10v0.

[0151] Figure 6This further demonstrates how the error in linearization can be estimated in the case of short time intervals (ignoring the acceleration term).

[0152] The same groove N is measured directly and continuously relative to its distance u. Due to the presence of uniform acceleration, subsequent measurements of the groove, for example, occurring at velocity v1, are compressed relative to the previous one (i.e., v1 > v0). There is one rotation between these two measurement events. In linearization, it is assumed that there is the same rotational speed / rate between the two measurement events. The time interval between the two measurement events is the time between two points at the same distance on the same side F1 (or F2). Therefore, the maximum error can be estimated.

[0153] Δv / Δt = (v1-v0) / Δt.

[0154] Figure 7 and 8 Two further advantageous variations of the invention are shown in the figure, which is a cross-sectional view of the motor spindle 3 of a machine tool. As is common in machine tool constructions, one side of the chuck 1, which has multiple clamping sections 2, is shown as being in an unclamped state (parts not shown), and is shown as being clamped in the motor spindle 3 or the chuck 1.

[0155] exist Figure 7 and Figure 8 In the clamping portion indicated by the motor spindle 3, a single cutting edge sensor 4 according to the present invention can be seen. Figure 7 In this context, sensor 4 has an effective range for radial alignment, and... Figure 8 In this context, it has an effective range for alignment within the rotation axis D. Therefore... Figure 7 The radial sensor 4 of the present invention is shown. Figure 8 The axial sensor 4 of the present invention is shown; however, Figure 7 and 8 What is not visible in the cross-sectional view is the second sensor 4, which is optionally available according to the invention, because if used, this would offset the arrangement in the circumferential direction, particularly by 90° or 180°, and therefore is not visible in the cross-sectional view. The arrangement with two sensors 4 according to the invention is visible in the cross-section, for example in... Figure 9 middle.

[0156] The changes to the cutting edge 53 of tool 50 in this application Figure 7 and Figure 8 The text does not provide further details, but it appears to describe how the tool 50 or cutting edge 53 is guided axially and / or radially relative to the axis of rotation D by load or applied force, in the region X of the spindle 5, or... Figure 7The region X of the counter-holder 6 or stop / ring element 6 of the motor spindle 3, schematically shown in the diagram, is deformed or widened in the radial direction R. Therefore, the distance 9 or gap 9 between the rotor unit or spindle 5 and the stator unit 10, including the radial sensor 4, is altered or reduced.

[0157] The state of the reference measurement in region X mentioned above is the specified state within the meaning of this invention, and the actual displacement and / or deformation or change in actual state sensed by the force / change in the cutting edge 53 is therefore advantageously used for monitoring / controlling the motor spindle 3, i.e. preferably for monitoring or inspecting a single cutting edge.

[0158] exist Figure 8 In this process, the axial alignment deformation of the measuring arm 11, including the axial sensor 4, or the axial change A in the distance 9, can be further sensed and processed. This axial change A is then transmitted to the tool receiving unit 8 and the element 6 via the force / change F on the cutting edge 53, or the axial and / or radial deformation / change on the cutting edge 53 of the tool 50.

[0159] exist Figure 9 The middle represents according to Figure 8 A simplified cross-sectional diagram of a variant shows an optional arrangement of the two sensors 4. These two sensors 4, and according to... Figure 7 The two radially oriented sensors 4 (not shown in more detail) are preferably offset by 90° or 180° in the circumferential direction. Symmetrical or asymmetric displacement and / or deformation / change of the motor spindle 3 and / or the reverse retainer 6 or stop / ring element 6 of the tool receiving unit 8 caused by the load on a single cutting edge can be sensed by the two sensors 4 and analyzed / evaluated in an advantageous manner.

[0160] exist Figure 10 The diagram schematically shows a commercially available tool 50 or milling cutter 50. It has a tool head 51, which in this case has four individual cutting edges 53 and a tool holder 52. The tool holder 52 is typically held in a tool holder, which is not shown in more detail, and the tool holder is inserted into a tool receiver.

[0161] Figure 12 This illustrates a drilling process with four cutting edges 53 (such as...) during one rotation. Figure 10 The example shown is an example of the axial deflection of the cutter 50 (the end mill 50 shown). Four peaks of deflection caused by the four cutting edges 53 are clearly shown here. In this case, one peak is slightly flattened, indicating a slightly damaged cutting edge 53 or a certain amount of wear.

[0162] exist Figure 11The image shown, for illustrative purposes, depicts a machining process in a groove where chip jamming has been caused by excessive feed motion. This can be seen in the middle region, at two very high peaks. As an example, in Figure 11 In the graph, a predetermined / critical threshold K is plotted, which has been exceeded by a second particularly high peak. This is to illustrate, for example, that the stored threshold K can be predefined for a specified state / value, and when exceeded (as by...). Figure 11 (As illustrated in the example) can result in a machine response and / or output of favorable signaling or display / alarm. In this way, for example, if excessively large chips may become stuck unfavorably at a machining point or at one of the cutting edges 53, this could lead to an immediate stop and / or alarm, thus enabling effective prevention of breakage of the tool 50 or the cutting edge 53 or inaccurate machining of the workpiece.

[0163] Tag list

[0164] 1 Machine Tool Unit

[0165] 2 stator units

[0166] 3 rotor units

[0167] 4 sensor ring

[0168] 5-axis sensor

[0169] 6 measuring rings

[0170] 7 electronic units

[0171] 8 Inspection devices

[0172] 9 Machine Control System

[0173] 10 casing

[0174] 11 Bearing Cover

[0175] 12-conical ring / tool ​​clamping device

[0176] 20 reference signals

[0177] 21 Measurement Signal

[0178] 23 Frequency Analysis

[0179] 24-frequency search

[0180] 25 Amplitude Assessment

[0181] 50 tools

[0182] 51 Tool Head

[0183] 52 tool handle

[0184] 53 cutting edge

[0185] 101 chuck

[0186] 102 Chuck Component

[0187] 103 motor spindle

[0188] 104 sensors

[0189] 105 spindle

[0190] 106 Stop

[0191] 107 components

[0192] 108 Tool Receiving Unit

[0193] 109 Distance

[0194] 110 stator unit

[0195] 111 Measuring Arm

[0196] A change

[0197] a acceleration

[0198] D Rotation axis

[0199] F force

[0200] The side of the edge of the F1 and F2 grooves

[0201] K threshold

[0202] N groove

[0203] R direction

[0204] t time

[0205] u distance

[0206] v0 Rotation speed / rate

[0207] X area

[0208] Δφ phase difference

Claims

1. A motor-driven machine tool unit (1, 103) having a stator unit (2, 110) and a rotor unit (3, 105) rotatable about a rotation axis (D), the rotor unit (3, 105) including at least one tool receiving unit (108) for receiving a tool, the tool receiving unit (108) specifically including a tool clamping device (101), the tool clamping device (101) being adjustable in the longitudinal direction of the rotation axis (D), and a clamping force being applicable to the tool clamping device (101) for fixing and clamping a releasably fixed tool shank of a tool (50), the tool head (51) of the tool (50) including at least one cutting edge (53), and having at least one tool sensor (5, 104) configured to sense a load on the tool (50), the tool sensor (5, 104) being implemented as a single cutting edge sensor for sensing a cutting edge load on a single cutting edge (53), characterized in that The stator unit (2, 110) includes at least the single cutting edge sensor, wherein, The single cutting edge sensor is implemented as a distance sensor for sensing the distance (109, u) between the stator unit (2, 110) and / or the distance sensor and at least a portion of the rotor unit (3, 105) and / or the tool receiving unit (108), the distance (109, u) being such that it can be changed by the cutting edge load on the single cutting edge (53).

2. The machine tool unit according to claim 1, characterized in that, The single cutting edge sensor is implemented as a single cutting force sensor for sensing the force applied to the single cutting edge (53).

3. The machine tool unit according to claim 1, characterized in that, When viewed in the axial direction (D), the single cutting edge sensor is at least partially arranged at the level of the tool clamping device (101) and / or the tool receiving unit (108).

4. The machine tool unit according to claim 1, characterized in that, The single cutting edge sensor is implemented as a non-contact operating sensor for non-contact sensing of the cutting edge load on the single cutting edge (53).

5. The machine tool unit according to claim 1, characterized in that, The single cutting edge sensor is implemented as an axial sensor having at least one sensing region aligned along the length direction of the rotation axis (D).

6. The machine tool unit according to claim 1, characterized in that, The rotor unit (3, 105) and / or the tool receiving unit (108) include at least one marker (N).

7. The machine tool unit according to claim 1, characterized in that, The machine tool unit (1, 103) is a multi-axis rotary head or a motor spindle.

8. The machine tool unit according to claim 1, characterized in that, The tool head (51) includes at least two cutting edges (53) or at least four cutting edges (53).

9. A machine tool, comprising a tool (50) and a machine tool unit (1, 103) according to any one of claims 1 to 8.

10. A method for sensing the cutting edge load on a single cutting edge (53) of a tool (50), wherein, The tool head (51) of the tool (50) having at least one cutting edge (53), the tool (50) and / or the tool holder for holding the tool (50) being received by a motor-driven machine tool unit (1, 103), the machine tool unit having a stator unit (2, 110), a rotor unit (3, 105) being mounted relative to the stator unit (2, 110) to be rotatable about a rotation axis (D), at least one tool sensor (5, 104) being used to sense the load on the tool (50), the tool sensor (5, 104) being implemented for sensing the cutting edge load of a single cutting edge (53), characterized in that the method comprises the following method steps: • Arrange a single cutting edge sensor on the stator unit (2, 110); • Provides at least one sensor head for a single cutting edge sensor to determine the distance (109, u) between the stator unit (2, 110) and / or the sensor head and at least a portion of the rotor unit (3, 105) and / or at least a portion of the tool receiving unit (108) / spindle head, the distance (109, u) being varied by the cutting edge load on the single cutting edge (53). Measure the distance (109, u) from the rotor unit (3, 105) and / or the tool receiving unit (108) / a portion of the spindle head. Record at least one time-related and / or position-related sequence of distances measured by a single cutting edge sensor and / or sensor head (20, 21), and The axial runout and / or radial runout and / or angular variation and / or torsional torque are determined by considering only the time-related and / or position-related sequences of the measured distance (109, u) and the portion of the rotor unit (3, 105) / tool ​​receiving unit (108) / spindle head rotating relative to a single cutting edge sensor and / or sensor head.

11. The method for sensing cutting edge load according to claim 10, characterized in that, Markings (N) are provided on the rotor unit (3, 105) and / or tool receiving unit (108) / spindle head. A single cutting edge sensor and / or sensor head senses the mark (N) on the rotor unit (3, 105) during measurement. The current rotational speed / rate (v0, v1) of the rotor unit (3, 105) is sensed based on the marker (N) sensed by a single cutting edge sensor and / or sensor head.

12. The method for sensing cutting edge load according to claim 10, characterized in that, The current rotational speed / rate (v0) of the rotor unit (3, 105) is determined based on the marker (N): During rotation, a specific angular segment of the rotor unit (3, 105) is marked as a marker (N), and the sensor head (5) is determined for the marker (N) in the case of a known angular segment to allow the single cutting edge sensor and / or sensor head to pass through the required time, and / or Measure the time between two consecutive detections of a mark (N) by a single cutting edge sensor and / or sensor head.

13. The method for sensing cutting edge load according to claim 10, characterized in that, The groove serves as a marker (N) such that the regions outside and inside the groove have different distances (109, u).

14. The method for sensing cutting edge load according to claim 10, characterized in that, Under normal cutting conditions, time-related and / or position-related sequences (20, 21) of distances (109, u) used as reference measurements were recorded.

15. The method for sensing cutting edge load according to claim 10, characterized in that, The marker (N) is used as an initial point, and the initial point used for evaluation is assigned to the distance sequence so that the distances of different sequences (20, 21) can be assigned to each other.

16. The method for sensing cutting edge load according to claim 10, characterized in that, The evaluation sequence of values ​​is determined by at least one of the following calculations: • The difference (22) between two in the time-related sequences (20, 21), followed by the previously formed Fourier transform (23) of the first and second time-related and / or positional sequences (20, 21), and / or • Fourier transform of the sequence in each case, followed by subtraction between the time-correlated sequences (20, 21) in the Fourier transform, and / or • Calculate the average of time-related and / or location-related sequences, and then calculate the difference between the averages.

17. The method for sensing cutting edge load according to claim 16, characterized in that, The evaluation sequence is searched (24, 25) for deviations exceeding a predefined threshold (K) or at least two deviations, and in the case of exceeding the threshold (K), a change in the cutting edge is assumed.

18. The method for sensing cutting edge load according to claim 16, characterized in that, In the evaluation sequence, the difference of the distance (109, u) is compared with a threshold (K), and if the threshold (K) is exceeded, a change in the cutting edge is assumed.

19. The method for sensing cutting edge load according to claim 10, characterized in that, Artificial intelligence is used to determine whether there are changes in the cutting edge.

20. The method for sensing cutting edge load according to claim 10, characterized in that, The tool head (51) includes at least two cutting edges (53) or at least four cutting edges (53).

21. The method for sensing cutting edge load according to claim 10, characterized in that, The tool (50) and / or the tool holder for holding the tool (50) are detachably fixed to the tool clamping device (12, 101, 108) of the tool receiving unit (108) of the rotor unit (3, 105).

22. The method for sensing cutting edge load according to claim 10, characterized in that, In the clamping of the tool (50), the tool clamping device (12, 108) is adjusted in the length direction of the rotation axis (D) and / or arranged in the spindle head and / or tool receiving unit (108) of the rotor unit (3).

23. The method for sensing cutting edge load according to claim 14, characterized in that, In normal cutting conditions, before and / or after the first machining operation by the machine tool unit (1, 103), time-related and / or position-related sequences (20, 21) of distances (109, u) used as reference measurements are recorded.

24. The method for sensing cutting edge load according to claim 14, characterized in that, For each tool (50) used, time-related and / or location-related sequences (20, 21) of the distance (109, u) used as a reference measurement were recorded individually.

25. The method for sensing cutting edge load according to claim 15, characterized in that, The marker (N) is used as an initial point, and the initial point for evaluation is assigned to the distance sequence so that the distances of different sequences (20, 21) can be assigned to each other in the difference (22) and / or Fourier transform (23).

26. The method for sensing cutting edge load according to claim 16, characterized in that, The Fourier transform (23) is the discrete Fourier transform.

27. The method for sensing cutting edge load according to claim 17 or 18, characterized in that, The changes in the cutting edge are wear and / or breakage of the cutting edge and / or blockage of the cutting edge / clamping.

28. The method for sensing cutting edge load according to claim 18, characterized in that, In the evaluation sequence, in the case of the frequency value corresponding to the number of revolutions per unit time of the rotor unit (3, 105), the difference of the distance (109, u) in the Fourier transform is compared with a threshold (K), and if the threshold (K) is exceeded, the change of the cutting edge is assumed.

29. The method for sensing cutting edge load according to claim 19, characterized in that, The determination of whether there is a change in the cutting edge is performed by applying artificial intelligence and by inferring errors and / or changes from the sequence (20, 21) through machine learning.

30. The method for sensing cutting edge load according to claim 19, characterized in that, The changes include wear and / or breakage of the cutting edge and / or blockage of the cutting edge / clamp.

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