Condition monitoring of a tool holder with a measuring device

Abstract

A method for monitoring the operating characteristics of a tool holder. In a method (100) for monitoring the operating characteristics of a tool holder (1), at least two measurement axis signals (x, y) from at least two radially oriented measurement axes (x, y) of sensors (9) arranged in the tool holder are used to form a resultant measurement axis signal (resultant (R)), and monitoring is performed using the resultant measurement axis signal or the resultant (R).

Description

[0001] This invention relates to a method for monitoring the working characteristics of a tool holder.

[0002] This method is exemplified by F. Bleicher et al.'s "In-Process Control with a Sensory ToolHolder to Avoid Chatter," Journal of Machine Engineering, 2018, Vol. 18, No. 3, pp. 16-27. The following are known: “Using Sensory Tool Holder Data for Optimizing Production Processes”, Journal of Machine Engineering, 2019, Vol.19, No.3, 43-55; or “Method for Determining Edge Chipping in Milling based on Tool Holder Vibration Measurements”, CIRP Annals-Manufacturing Technology 69(2020)101-104.

[0003] Here, the tool holder to be monitored is designed to rotate about a tool holder rotation axis (D) that defines the axial direction, and has a tool section with a tool receiving structure for receiving the tool at one longitudinal end of its axial direction, and a connection section with a connection structure at the other longitudinal end of its axial direction for connecting with the machine tool spindle in a torque-transmitting manner.

[0004] In addition, the tool holder to be monitored has a measuring device for detecting data related to the operation of the tool holder. This measuring device is a single-axis accelerometer with a single measuring axis radially oriented relative to the rotation axis (D) of the tool holder, wherein the accelerometer generates a measuring axis signal associated with this radial measuring axis.

[0005] The operating characteristics of this tool holder are monitored in the following way, for example, by observing vibrations or identifying instabilities (such as chatter) in the tool holder during milling (here, the milling tool is received in the tool receiving structure of the tool holder): the measurement axis signal measured by the single-axis accelerometer during milling is analyzed in a time curve or in a frequency spectrum. Thus, for example, an "abnormal" (e.g., step) change in the measurement axis signal of the single-axis accelerometer on the time curve can indicate instability.

[0006] A drawback of using a tool holder with a measuring device / accelerometer (e.g., under consideration) to monitor milling operations may be that the signals / data provided by the measuring device of the tool holder for the machining process (especially in the absence of a suitable evaluation method) may not adequately or convincingly reflect the operation of the tool holder (e.g., the milling process in this case), thus resulting in insufficient monitoring of the process. In short, a tool holder with a measuring device here provides process signals / data that are difficult to interpret in terms of the process itself.

[0007] Therefore, the object of this invention is to provide a method for monitoring the working characteristics of a tool holder using a measuring device, which avoids the disadvantages of the prior art, and in particular improves upon the prior art, thereby enabling more persuasive reflection and monitoring of the working and / or working characteristics or machining process in or on the tool holder.

[0008] This objective is achieved by a method for monitoring the operating characteristics of a tool holder, as described in the independent claims. Advantageous improvements of the invention are the subject of the dependent claims and the following description.

[0009] Terms used, such as top, bottom, front, rear, left, or right, should be understood according to common usage unless otherwise explicitly defined. Terms such as radial and axial should be understood with reference to the tool holder's axis of rotation (D).

[0010] The term “substantially” (according to the Supreme Court’s interpretation) can be understood to mean “to a degree that is still substantially substantial in practice.” Due to factors such as manufacturing or assembly tolerances, there may be unintentional (i.e., without functional justification) deviations from the precision implied by the term.

[0011] This method for monitoring the operating characteristics of a tool holder proposes a tool holder designed to rotate about a tool holder rotation axis (D) that defines an axial direction.

[0012] In addition, the tool holder to be monitored has a tool section with a tool receiving structure for receiving the tool at one longitudinal end of its axial direction, and a connection section with a connection structure at the other longitudinal end of its axial direction, which is used to connect with the machine tool spindle of the machine tool in a torque-transmitting manner.

[0013] In addition, the tool holder to be monitored also has a measuring device for detecting data related to the operation of the tool holder.

[0014] The measuring device is a sensor, particularly an acceleration sensor, having at least two measuring axes (e.g., denoted by x and y) that are substantially radially oriented relative to the tool holder rotation axis (D).

[0015] If necessary, it may be beneficial that the at least two measuring axes (e.g., denoted by x and y) are also orthogonally oriented to each other, and that the two measuring axes (x, y) are substantially radially oriented relative to the tool holder rotation axis (D).

[0016] Furthermore, it is also advantageous to align at least two measuring axes, which are substantially radially oriented relative to the tool holder's rotation axis (D), with the tool holder's alignment features (e.g., a follower in Deutsches Eck or HSK). Through sufficiently fast (real-time) communication with the machine tool control unit, rotation angles can then be assigned. This allows vibration to be indicated in a pointer-like manner in the machine tool coordinate system.

[0017] However, the measuring device may also include other sensor systems that provide signals about direction, such as force sensors, velocity sensors, deformation sensors, or displacement measuring systems.

[0018] The invention will be explained below, for example, by using or based on an acceleration sensor.

[0019] The accelerometer provides at least two measurement axis signals associated with at least two (radial) measurement axes, which (are evaluated or interpreted, and are typically processed as (measurement) data) describe or reflect the operation of the tool holder, for example, corresponding to measurement axes x and y (also referred to as x and y).

[0020] For simplicity, these terms (measurement) signal, (measurement) value, and (measurement) data can also be used synonymously with each other.

[0021] In this method for monitoring the working characteristics of the tool holder, at least two measurement axis signals are used to form a composite measurement axis signal, hereinafter simply referred to as the "composite result" (R), and monitoring is performed using the composite result.

[0022] Here, the composite measurement axis signal or composite result of the at least two measurement axis signals, as is common in the field of (mathematical) mechanics, can be understood as a (vector) sum, but can also be understood as any (mathematical calculation) rule that performs mathematical operations on the two measurement axis signals together, and the result is the composite.

[0023] In mathematics, this can be simply expressed as R = f(x,y), where f represents the mathematical calculation rule.

[0024] Therefore, the synthesis result (R) can be formed, for example, according to the following rules:

[0025] R(x i =Sqr(Sum(x) i 2 )) (1)

[0026] in:

[0027] x i Measurement axis signal of axis i

[0028] Sqr square root

[0029] Sum

[0030] ((1) is also a vector, especially when the sensor orientation is non-orthogonal).

[0031] This method is based on the understanding that, on the one hand, an accelerometer designed and arranged in the tool holder (which has at least two measuring axes that are substantially radially oriented relative to the tool holder's axis of rotation (D)) can better describe or reflect the operation of the tool holder by the (measurement) signals / (measurement) data generated by it, and thus more convincingly describe the machining process using the tool holder (which is sensed in this way).

[0032] On the other hand, only a composite result formed using signals from at least two measuring axes can provide a convincing reflection of the machining process.

[0033] This allows for more reliable analysis and improved predictions, such as abnormal operating conditions, instability, tool breakage, or tool wear.

[0034] Tests conducted with tool holders equipped with sensors have shown that, in particular, simple single-axis sensors or tool holders with simple single-axis sensors may provide less convincing data about the machining process, which is therefore less likely to reliably identify abnormal working conditions, instabilities, tool breakage, tool wear, etc.

[0035] For example Figure 10The machining / sensor data for the tool holder are shown, here for an end mill with z = 4 teeth, featuring a single-axis accelerometer with a radially (32) oriented measuring axis. The process parameters are n = 2400 rpm, a P (Depth of cut) = 2mm and a e (Working engagement) = 4mm.

[0036] Here, Figure 10 A 3D view is shown showing the spectral analysis over time (spectral graph). Here, the time axis extends from bottom to left, and the frequency increases from right to bottom. The expected gear meshing frequency is 160Hz. This gear meshing frequency is... Figure 10 At first glance, it's not noticeable.

[0037] In comparison, Figure 11 The machining data / sensor data of the tool holder are shown, here again for an end mill with z=4 teeth, in which case a two-axis accelerometer is used, which has two orthogonal, radially (32) oriented measurement axes (x, y). These two (measurement / measurement axis) signals x, y, or their (measurement) data, are determined according to the following rules.

[0038] R(x i =Sqr(Sum(x) i 2 )) (1)

[0039] in:

[0040] Measurement axis signal of xi axis i

[0041] Sqr square root

[0042] Sum

[0043] The synthesis result R was obtained. xy .

[0044] The process parameter is also n = 2400 revolutions per minute.

[0045] a P (Depth of cut) = 2mm and a e (Working engagement) = 4mm.

[0046] Figure 11 The spectral analysis over time is shown again in a 3D view. Here, the time axis also extends from bottom to left, and the frequency increases from right to bottom. The expected gear meshing frequency is also 160Hz, but this time... Figure 11 The dominant frequency can be clearly seen in the middle (marked with ZEF).

[0047] Therefore, it is shown that the combination of at least two-axis accelerometers and the synthetic results formed by their measurement signals can reflect or describe the working characteristics of the tool holder, thereby reliably identifying abnormal working conditions, instabilities, tool breakage, tool wear, etc. in the tool holder.

[0048] Advantageously, the accelerometer also has a third measurement axis, for example referred to as z (where the corresponding (measurement axis) signal / value / data can also be represented by z), wherein the third measurement axis is substantially axially oriented relative to the tool holder rotation axis (D), so the accelerometer also provides a third measurement axis signal (z) associated with the third measurement axis, and in particular the synthesis result (R) can also be formed using the third measurement axis signal if necessary.

[0049] However, the third measurement axis signal (7) can also be evaluated separately if necessary, because the characteristics of the third measurement axis or z-axis (because of the different way it is excited) may be slightly different from those of the first measurement axis or x-axis and y-axis, since the main excitation occurs in the measurement plane of these first measurement axes or x-axis and y-axis.

[0050] Here, it is known from the cutting force test using a multi-component force gauge that, under unstable conditions, the axial shaft signal will show significant signal changes.

[0051] If necessary, the third measuring axis or z-axis is subjected to different excitations, and the third measuring axis or z-axis can be considered for detecting, for example, flutter, because even in a force measuring platform, this axis exhibits very obvious force abrupt changes during flutter.

[0052] Furthermore, it can be proposed to wirelessly transmit raw or processed measurement axis signals and / or data to the evaluation unit, particularly the Condition Monitoring System (CMS). This can be achieved, for example, according to known (radio) standards and / or via Bluetooth.

[0053] Furthermore, it is beneficial to perform statistical processing on the raw or processed measurement axis signals and / or data, especially smoothing, filtering, or frequency analysis.

[0054] It can also be proposed to transform the original or processed measurement axis signals and / or data, especially from a rotating system (e.g., a coordinate system that rotates with the tool holder and is expanded by these measurement axes) to an inertial system.

[0055] Of particular advantage is the placement of the accelerometer sensor on or near the tool holder's axis of rotation (D). The positioning of the accelerometer sensor has the following effect: the square of the rotational speed n is related to the basic load a. zp(Centripetal acceleration) is related, and therefore the distance between the accelerometer and the tool holder's rotation axis (D) should be kept as small as possible to monitor high rotational speeds. Thus, the measurement range of the accelerometer is only slightly limited.

[0056] The influence of rotational speed on the measurement results is reflected in the time signal as amplitude changes with the basic load a. zp The magnitude of the deviation is significant. This must be taken into account when considering the vibration intensity in the time signal for evaluation. The measured maximum value then does not correspond to the excitation of the process, and only becomes convincing after subtracting the deviation.

[0057] With proper calibration of the measurement system, it is even feasible to analyze the basic load a. zp To identify the radial runout error of the tool clamped in the machine tool spindle.

[0058] It is also preferable to propose automatically adapting and / or changing the process parameters and / or operating parameters of the machine tool with the tool holder in the machining process / operation based on monitoring. Intuitively and simply, it is advantageous to control and / or regulate the machining process by means of monitoring results. If the monitoring results, for example, show chatter, the machine tool's rotational speed can be changed, or the machine tool can be slowed down in a controlled manner at the first signs of tool breakage.

[0059] Furthermore, it is advantageous that the tool holder, in addition to the accelerometer, also has other electronic components, particularly: a microcontroller, one or more transmission devices, particularly one or more antennas, one or more printed circuit boards, and / or one or more power supply devices.

[0060] According to the proposed improvement plan, the tool receiving structure may be a heat-shrink chuck, a hydraulic expansion chuck, a tool headstock, a collet chuck, or a power chuck.

[0061] The connection structure may also be, for example, a hollow shaft cone or a steep cone (Steilkegel) and / or a joint structure for a ball clamping system or a polygonal hollow shaft.

[0062] This method can be preferably used to identify abnormal operating / process conditions of tools or tools housed in a tool holder, particularly instability and / or chatter and / or wear and / or breakage, wherein the identification is performed by analysis using the synthesized results.

[0063] This method can also be used for automated machine tool control, wherein process parameters and / or operating parameters of the machine tool are automatically adapted and / or changed based on monitoring as the tool holder is in the machining process / operation.

[0064] Furthermore, an intelligent (“intelligent”) tool holder may be proposed, having at least one tool holder designed to rotate about a tool holder rotation axis (D) defining an axial direction, and having a tool section at one longitudinal end of its axial direction with a tool receiving structure for receiving a tool, and a connection section at the other longitudinal end of its axial direction with a connection structure for torque-transmitting connection to a machine tool spindle, and the at least one tool holder having a measuring device for detecting data related to the operation of the tool holder, the measuring device being an accelerometer having at least two measuring axes oriented substantially radially relative to the tool holder rotation axis (D), the accelerometer providing at least two measuring axis signals associated with the at least two measuring axes, and the intelligent tool holder having an evaluation unit, such as a CMS, configured to perform the method or one of its improvements.

[0065] In short, this intelligent tool holder is equipped with a tool holder (or an improved tool holder) proposed according to the method and an evaluation unit that performs the method (or one of its improvements).

[0066] The accelerometer can be designed differently. Therefore, according to one improvement, the accelerometer can have (exactly) two measuring axes oriented particularly orthogonally to each other. According to another improvement, the accelerometer can also have three measuring axes (in this case, unfolded into an orthogonal coordinate system), wherein, in this case, the third measuring axis can be oriented substantially axially relative to the tool holder rotation axis (D).

[0067] It is also advantageous that the synthesized result (R) is formed by means of an evaluation unit (e.g., a microprocessor / microcontroller) or within the scope of condition monitoring (CM) or in a condition monitoring system (CMS).

[0068] Furthermore, it can be proposed that the accelerometer is arranged on a separate printed circuit board, particularly on a different printed circuit board than the microcontroller. This allows for more flexible arrangement of components within the tool holder and enables an advantageous modular construction system (with flexible interchangeability).

[0069] Here, the printed circuit board carrying the microcontroller can be designed as a flexible printed circuit board, which thus provides a favorable mounting situation in the tool holder.

[0070] One or more transmission devices or antennas may also be arranged on one or more separate printed circuit boards.

[0071] Thus, this distributed arrangement enables an advantageous modular structure in the tool holder, which offers simplified interchangeability.

[0072] However, it can also be beneficial to combine basic components in the electronic structure unit (such as sensor / μC-combination) onto a single chip.

[0073] Advantageously, the antenna can be an SMD (surface mounted device) antenna, a wired antenna, or a self-adhesive foil antenna. It can also be proposed that the SMD antenna or wired antenna is arranged on a separate printed circuit board (modular structure / modular system).

[0074] Furthermore, it can be proposed that the transmission equipment (especially the antenna) and / or power supply device be arranged to be embedded in a settling portion on the outer surface of the tool holder.

[0075] Such a settling portion can be advantageously designed as a circular, bag-like portion on the outer surface of the tool holder, which is cast and / or covered, particularly by means of silicone material.

[0076] According to the improved design, two or more transmission devices are provided, particularly two or more antennas, especially wired antennas, which are arranged in a circumferential direction around the rotation axis (D) of the tool holder. Therefore, if, for example, one of the two or more antennas experiences transmission obstruction, the other one or more antennas can (redundantly) transmit data. This ensures uninterrupted data transmission.

[0077] Furthermore, it can be proposed that one or more connecting holes extend obliquely relative to the tool holder rotation axis (D), particularly connecting holes for the connection lines of the accelerometer or antenna extending obliquely relative to the tool holder rotation axis (D). The oblique holes with associated cable guides help prevent cable kinking and thus make the system more reliable.

[0078] The improved scheme also proposes that the accelerometer has an SPI interface, and / or the electronics in the tool holder have an SPI interface and / or an SPI bus. In short, in this method, values / data / signals are preferably transmitted via an SPI interface. The SPI interface or bus allows for high data rates, e.g., higher than 1. 2 C interface.

[0079] Furthermore, it can be beneficial that energy supply is achieved through energy harvesting, particularly kinetic energy, where the coolant flow in the tool holder, especially through a turbine in the coolant passage of the tool holder, is used for energy generation.

[0080] Alternatively or additionally, it is conceivable that energy can be supplied by means of batteries and / or accumulators.

[0081] Of particular advantage is that the machine tool is equipped with the method according to the invention and the tool holder according to the invention, or the method or tool holder as described above. This allows for monitoring of the process on the machine tool.

[0082] The description of the invention given to date and the advantageous embodiments thereof comprise numerous features, which are embodied individually and in combination in several (independent / dependent) claims. However, these features may also be advantageously considered individually for one tool holder and / or combined into other meaningful combinations.

[0083] Even if certain terms are used in the specification or in the patent claims, either in the singular or in relation to quantifiers, the scope of the invention using these terms should not be limited to the singular or the corresponding quantifier. Furthermore, the words “an” or “a” are not to be understood as quantifiers, but rather as indefinite articles.

[0084] The features, characteristics, and advantages of the present invention described above, as well as the ways and methods of implementing them, will become clearer and more readily understood in conjunction with the following detailed description of embodiments of the invention illustrated in one or more accompanying drawings / figures (the same components / parts and functions have the same reference numerals in the drawings / figures).

[0085] These embodiments are used to illustrate the invention, and the invention is not limited to the combinations of features given therein, nor is it limited in terms of functional features. Furthermore, each feature suitable for this invention can be clearly viewed separately, removed from the embodiments, introduced into other embodiments to supplement other embodiments, and combined with any of the claims.

[0086] In the attached diagram:

[0087] Figure 1 A tool holder with a chuck (here, a heat-shrink chuck) according to one embodiment is shown.

[0088] Figure 2 It shows that according to Figure 1 Part of a tool holder with a battery compartment and an antenna pouch-like section.

[0089] Figure 3 The location of the (flexible) main circuit board is shown according to Figure 1 A view of the tool holder.

[0090] Figure 4 It shows the method for using according to Figure 1 The tool holder has a (flexible) main circuit board with protective films on the front and back, and includes sensor terminals, a microcontroller (μC), and an antenna terminal.

[0091] Figure 5 It shows the method for using according to Figure 1 The tool holder's (flexible) main circuit board has sensor terminals (plug-in contacts), a microcontroller (μC), an antenna terminal, programming contacts, and power supply device terminals (plug-in contacts).

[0092] Figure 6 The location of the sensor is shown according to Figure 1 A view of the tool holder.

[0093] Figure 7 A sensor circuit board is shown, which has a function for... Figure 1 The sensor and wiring of the tool holder,

[0094] Figure 8 A sensor circuit board with a sensor and a sensor based on... are shown. Figure 1 The (flexible) main circuit board with tool holder wiring.

[0095] Figure 9 A tool holder with a chuck (here, a heat-shrink chuck) according to another embodiment with two wired antennas is shown.

[0096] Figure 10 The machining data / sensor data (time curve) of the tool holder with a single-axis accelerometer are shown.

[0097] Figure 11 Machining data / sensor data (spectral diagram) of a tool holder according to the invention with a two-axis accelerometer sensor having two radial measurement axes are shown.

[0098] Figure 12 A schematic diagram of a method for monitoring the operating characteristics of a tool holder (e.g., the tool holder according to the aforementioned embodiment) is shown.

[0099] Figure 13 The diagram illustrates the synthesized result R of a tool holder with a biaxial accelerometer according to the invention during a machining process (milling), the biaxial accelerometer having two radial measurement axes.

[0100] Figure 14 The following diagram illustrates the time curve of a tool holder with a biaxial accelerometer according to the present invention during a machining process (milling). Figure 13 The spectrum of the synthesized result R, the biaxial accelerometer with two radial measurement axes.

[0101] Condition monitoring using a sensor-based tool holder

[0102] - Tool holder with sensor 1 ( Figures 1 to 8 )

[0103] Figure 1 A first embodiment of the tool holder 1 according to the present invention is shown, which will be simply referred to below as tool holder 1 or first tool holder 1.

[0104] The tool holder 1 includes a tool holder base 35, which will be referred to as base 35 in the following text. The base 35 is integrally constructed here to achieve the highest possible rigidity. It is made of metal in a conventional manner.

[0105] The unity in the sense of this application also lies in the fact that a component is produced by an additive method, for example, from metal powder, or is composed of multiple components that are inseparably assembled, for example, by welding or brazing.

[0106] (Axially 31) The tool holder 1, which extends along the tool holder rotation axis D (hereinafter referred to only as the rotation axis D), has a tool section 3 at its longitudinal end 2 on the tool side and a connection section 6 at its longitudinal end 5 on the opposite connection side.

[0107] The tool section 3 includes a tool receiving structure 4 in the form of a tool receiving recess 4. Figure 1 The shank of the tool (not shown) can be axially 31 introduced into the tool receiving recess 4 from the longitudinal end 2 on the side of the tool.

[0108] The tool section 3 of the tool holder 1 is implemented as a heat-shrink chuck in a manner known per se. Figure 1 The shank of the tool (not shown) can be clamped in the heat-shrink chuck by utilizing the thermal expansion and contraction of the base material.

[0109] In tool holder 1 Figure 1 In the example shown, the connecting section 6 includes a connecting structure 7 in the form of a hollow shaft cone (or simply HSK).

[0110] As can be shown with the aid of other embodiments (not shown), the tool section 3 can also be formed according to another clamping principle, such as that of a hydraulic expansion chuck. Similarly, unrelated to this, the connecting section 6 can be designed to have a different shank shape.

[0111] The operating structure 36 for manipulating the tool holder 1 can be, for example, arranged axially 31 between the tool section 3 and the connecting section 6 via a clamping device. Figure 1 As shown, the manipulation structure 36 may include a clamping groove 37 extending around the rotation axis D in the circumferential direction 21.

[0112] exist Figure 1In the example shown, the base 35 is completely penetrated in the axial direction by the central recess 38, wherein the tool receiving recess 4 forms an axial section that can be used in particular to supply coolant through the tool holder 1 to the machining position, where, for example in milling, the tool (not shown) clamped in the tool holder 1 is in machining engagement with the workpiece to be machined.

[0113] In order to monitor the operation of the tool holder 1 during workpiece machining, the tool holder 1 is equipped with a measuring device 8.

[0114] This measuring device 8 can also, for example, identify abnormal conditions in the tool holder 1, such as tool breakage / wear, vibration, or other instabilities (such as chatter). For this purpose, the signals / data from the measuring device are analyzed and evaluated / processed.

[0115] For this purpose, the measuring device 8 is equipped with various components arranged on the tool holder 1 and interconnected (via cables), such as an acceleration sensor 9, an SMD antenna 11, a microcontroller (μC) 10, and a voltage / energy supply device or battery 16 (see especially). Figures 2 to 8 These components (in a modular structure as described below) are mostly placed on separate circuit boards 12, 13, 14, 15 that are connected to each other by connecting lines / cables 23 (not shown), 24, 25, such as the main circuit board 14 with a microcontroller (μC) 10, the (sensor) circuit board 13 with an acceleration sensor 9, and the (antenna) circuit board 15 with an SMD antenna 11.

[0116] - Two-axis accelerometer 9

[0117] Especially Figures 6 to 8 It is clearly shown that, in this case, the biaxial accelerometer 9 is the main component of the measuring device 8, and the two measuring axes x and y of the biaxial accelerometer are arranged orthogonally to each other.

[0118] Implemented modularly and to be independent of other components of the measuring device 8, this accelerometer 9 is placed separately on a separate (sensor) circuit board 13 (see [link]). Figure 7 and Figure 8 )superior.

[0119] In order to keep the effect of the rotation of the tool holder 1 on the centrifugal force of the accelerometer 9 as low as possible, especially as Figure 6 As shown, the accelerometer 9 is located on the center / rotation axis D in the tool holder 1, where the (orthogonal) measuring axes x and y are oriented normally relative to the rotation axis D (thus measuring radial (32) acceleration in these axial directions x and y) (see... Figure 6 ).

[0120] Instead of this two-axis accelerometer 9, a three-axis accelerometer can also be used, in which the three measuring axes x, y, z are unfolded into an orthogonal coordinate system, and the third measuring axis z of the three-axis accelerometer is oriented 31 axially relative to the tool holder rotation axis (D).

[0121] Similarly, Figure 6 As shown, the (sensor) circuit board 13 is bonded to the housing 39, which (in place of the coolant pipe) can be screwed into the tool holder 1. The accelerometer 9 is directly bonded to the housing 39 using instant adhesive.

[0122] Especially from Figure 8 and Figure 7 As can be seen, the connection between the (sensor) circuit board 13 and the main circuit board 14 is achieved in a wired manner (connection line 23 for the accelerometer 9 and plug 40 for the plug-in contact 26 of the connection line 23). Therefore, corresponding plug-in contacts 26 are provided on the main circuit board 14 for the plug 40. Alternatively, a wireless connection can be provided between these components instead of a wired connection.

[0123] - Main board 14 with microcontroller (μC) 10

[0124] To integrate the main circuit board 14 carrying the microcontroller (μC) 10 into the tool holder 1, such as Figure 3 As shown, a circular or annular groove 33 concentric with the rotation axis D is introduced into the tool holder 1. The groove extends around the central recess 38 in the tool holder 1 or around the area of ​​the coolant pipe (not shown here due to the acceleration sensor).

[0125] like Figure 2 As shown, the annular groove 33 is closed by a screw-on cover 34, which is advantageous because the surface is part of the HSK interface for ejecting the tool holder 1 from the spindle.

[0126] Similar to the (sensor) circuit board 13 in the sensor housing 39, the main circuit board 14 is cast with a protective silicone coating after all components have been assembled in the annular groove 33 (19).

[0127] like Figures 3 to 5 As shown, the main circuit board 14 is designed as a flexible "strip," which offers significant advantages, especially for assembly. The flexible circuit board can be effortlessly shaped into the circular recess 33 (see also [here]). Figure 3 and Figure 4 Furthermore, it can be more easily handled / assembled into a rigid form when connecting various connecting lines / cables 23, 24 (not shown), 25.

[0128] Figure 5 A top view of the assembled main circuit board 14 is shown (without connected wires / cables 23, 24, 25 (see also)). Figure 8 )). Figure 5 The top surface of the main circuit board 14 is shown, on which all the components are mounted; only printed wires are on the back surface of the main circuit board 14.

[0129] All connecting wires / cables 23, 24 (not shown), 25, such as the connecting wire / cable (23) for the accelerometer 9, the connecting wire / cable (25) for the power supply device 16, and the connecting wire / cable (24 (not shown)) for the antenna 11, are implemented through plug-in contacts 26, 27, 28, which facilitates simple and flexible assembly.

[0130] In (such as) Figure 5 The left edge of the main circuit board 14 (as shown) is the plug-in contact 26 for the connection line 23 or plug 40 of the accelerometer 9. The (unused) contact 29 located below can be used for other sensor signals if necessary.

[0131] A microcontroller (μC) 10, containing various components, reads signals / data from the accelerometer 9 and is placed (e.g., Figure 5 (As shown) The center of the main circuit board 14 is slightly to the left.

[0132] The signal / data is read from the accelerometer 9 via SPI, which in this case provides values ​​for both measurement axes (i.e., x and y).

[0133] If more than one value is needed at a given time point, all values ​​must be transferred in a single read operation. After the read operation is complete, the value from accelerometer 9 is discarded, and the next value in chronological order is loaded for use in the next read operation.

[0134] Accelerometer 9 transmits data byte by byte, with each value consisting of two bytes. Additionally, accelerometer 9 transmits the "back" of the total value first, followed by the "front," which must be combined by the software of microcontroller (μC) 10. This data is then aggregated by microcontroller (μC) 10 and prepared for transmission.

[0135] In (such as) Figure 5 The main circuit board 14 shown has two possibilities for connecting the antenna (i.e., plug-in contacts) on the right side of the center. One of the plug-in contacts (here, these upper plug-in contacts or an upper plug-in contact 27) is used in the first tool holder 1 for the SMD antenna 11, which transmits signals / data (Bluetooth transmission) to the outside of the tool holder 1, such as CMS.

[0136] In (such as) Figure 5 Multiple programming contacts 30 can be seen on the right side of the main circuit board 14 (as shown), and terminals or plug-in contacts 28 for the voltage / energy supply device 16 can be seen on the right edge of the main circuit board 14.

[0137] To protect the components of the main circuit board 14, the front and back of the main circuit board 14 may be covered with a protective film 42 if necessary. Figure 4 As shown.

[0138] -SMD antenna 11

[0139] Placed on a separate antenna circuit board 15 (see Figure 2 The SMD antenna 11 on the tool holder 1 is mounted on the tool holder 1 via the circular bag-shaped portion 17 on the clamping ring 43 (e.g. Figure 1 and Figure 2 As shown, the circular bag-shaped portion is connected to the circular groove 33 that houses the main circuit board 14 via an eccentric, angled connecting hole / connecting hole 22 (for connecting line 24 (not shown) to avoid bending on the connecting line 24 (not shown)).

[0140] If necessary, an identical second circular pouch (17) can be introduced into the clamping ring (43) to improve the balance mass of the tool holder 1 on the one hand, and to enable other antenna schemes with two antennas (11) (and, if necessary, improved transmission power) (see here). Figure 9 Or according to the second embodiment of the tool holder 1 having two wired antennas 11). For this purpose, a second antenna terminal (here another plug-in contact 27) has been provided on the main circuit board 14 (see above).

[0141] In order to secure the antenna circuit board 15 in the circular pouch 17, the circular pouch is cast with silicone resin (19) (or covered), or the same silicone resin protective coating 19 used for the main circuit board 14 can be used.

[0142] -Energy supply device / battery 16

[0143] Similar to SMD antenna 11, such as Figure 1 and Figure 2 As shown, the energy / voltage supply device 16 or battery 16 is placed through another circular pouch 17 (battery compartment 45) on the clamping ring 43, which is also connected to the circular groove 33 that accommodates the main circuit board 14 through an eccentric, inclined (for the connection line 25) connection hole 22 (to avoid bending on the connection line 25).

[0144] Battery 16 is secured in battery compartment 45 by a screw-on cover 20 (see...) Figure 1 This is achieved by screwing the cover onto the battery compartment 45, sealing the battery compartment, and simultaneously establishing contact between the cover and the battery 16. The cover 20 also allows for external replacement of the battery 16.

[0145] If necessary, a seal (not shown) may also be provided in the battery compartment 45 to protect the battery compartment from liquid intrusion (not shown).

[0146] - Tool holder with sensor 1 ( Figure 9 )

[0147] Figure 9 Another embodiment of the tool holder 1 according to the present invention is shown, which is simply referred to as the second tool holder 1.

[0148] This additional or second tool holder 1 is related to the tool holder according to the first embodiment, namely the first tool holder 1 (see...). Figures 1 to 8 The only difference is that the second tool holder is equipped with another antenna 11.

[0149] In addition, this second tool holder 1 is also equipped with an acceleration sensor 9 as in the first embodiment, and also with all other components (but not further mentioned here, but described in conjunction with the first tool holder 1). A more detailed explanation of this can be found in the description given for the first tool holder 1.

[0150] Unlike the first embodiment (here, the SMD antenna 11 is mounted in a circular pouch 17 on the outer periphery 21 of the first tool holder 1 (see...) Figure 2 )),like Figure 9 As shown, this second tool holder 1 is equipped with two wired antennas 11, which are also arranged in a way that embeds them in the circular bag-shaped portion 17 and are evenly distributed on the outer periphery 21 of the second tool holder 1. These wired antennas are also connected to the main circuit board or the antenna terminal / plug-in contact 27 thereon via connecting wires / cables.

[0151] Here, the circular pouches 17 on the outer periphery 21 of the tool holder 1 that accommodate the two wired antennas 11 can also be cast again with silicone resin (19) (or covered instead).

[0152] -The process status of the machine tool / machining machine is monitored by means of a tool holder 1 equipped with sensors. Figures 12 to 14 )

[0153] Figure 12 A tool holder 1 for monitoring is shown, for example, a tool holder 1 according to the aforementioned embodiment (see...). Figures 1 to 9A schematic diagram of a method 100 for Condition Monitoring (CM).

[0154] Figure 12 This is illustrated in the form of a (block) diagram of a control and regulation device 203 (as part of CM or CMS 201) for a machine tool 202 (or other machining machine), which is implemented to have one of the tool holders 1 as described above (and thus is able to provide measurement data about the machining process by means of an acceleration sensor 9).

[0155] As described above and in Figure 12 As shown, the measurement signal, which is received by the sensor-type tool receiver 1 and preprocessed if necessary, is transmitted via Bluetooth 150 to the CMS 201 or the control device 203 therein. This control device can respond specifically to emerging and / or persistent unstable states, or regulate such or similar abnormal process states.

[0156] This is accomplished by real-time adaptation / change 160 of the machining parameters (e.g., feed, speed, etc.) of the machine tool 202, wherein such adaptation / change 160 is implemented based on process states (e.g., vibration, chatter, or forces introduced onto the tool) (as learned from these measurement signals / data from the sensor tool holder 1), wherein these process states are detected by the measurement signals / data from the sensor tool holder 1 and transmitted to the control device 203.

[0157] like Figure 12 As shown, the control device 203 mainly consists of a data detection and evaluation unit 204, which judges the process stability (normal / abnormal (process unstable)) 120, and changes the machining parameters of the machine tool 202 160 when necessary through the control device 203 (if the process stability does not meet the requirements (normal state)).

[0158] Here, the (Bluetooth) receiver 205 (transceiver) of the CMS 201 that receives measurement signals / data from the sensor-type tool holder 1 is connected to this data detection and evaluation unit 204 via a real-time channel, which enables the system to achieve real-time capability.

[0159] The evaluation unit 204 obtains measurement data from the accelerometer 9 (which moves / rotates with the tool holder 1), stores this measurement data in a buffer memory, and immediately runs various algorithms, especially the synthetic result R formed from the measurement axis signal / data 110 as described above, for the purpose of identifying / detecting the process state 120.

[0160] The algorithm used is designed to determine under what conditions the control of machine tool 202 is (automatically) intervened 160.

[0161] Part of these algorithms determines the process status based on measurement signals / data from the sensor-based tool receiver 1.

[0162] Here, in particular, based on the two measurement axis signals x and y of the two-axis accelerometer 9 of the tool holder 1, the composite result (R) is formed according to the following rules:

[0163] R(x i =Sqr(Sum(x) i 2 )) (1)

[0164] in:

[0165] x i Measurement axis signal of axis i (here, x and y)

[0166] Sqr square root

[0167] Sum: total.

[0168] If the measurement axis signals x and y of the two-axis accelerometer 9 of the tool holder 1 are provided by the rotating system, they can be transformed 140 if necessary, that is, the coordinates of the rotating system of the tool holder 1 are transformed to the inertial system in this case.

[0169] If necessary, in order to eliminate measurement errors, outliers, etc. in these measurement axis signals x, y or measurement data, these measurement axis signals can also be statistically processed 130, for example, smoothed.

[0170] Evaluation unit 204 then performs analysis of the evaluation unit, particularly based on various representations of these processed or evaluated measurement axis signals x, y, or measurement data (such as, especially, on time curves and as a composite result R of a spectrum), for the purpose of identifying / detecting process status.

[0171] For example Figure 13 The time curve of the composite result R of the sensor tool holder 1 during the machining process (milling) is shown (horizontal axis: t (time); vertical axis: composite result R or its magnitude as a multiple of the normal acceleration g (the magnitude of the composite result)). (The corresponding composite result or its curve is also generated during the transformation to the inertial frame; for simplicity, "data that rotates together" should be considered here).

[0172] As shown in the synthesized result R (on the time curve), gear meshing begins after approximately 0.5 s, and the amplitude (i.e., the value of the synthesized result R) increases only slightly.

[0173] After about 5.5 seconds, the synthesized result R suddenly increases by about 70g, which allows us to infer that there are initial instabilities, such as flutter, in the process.

[0174] After approximately 10 seconds, the feed is reduced to v = 0 mm / min until the tool rotates in place and stops moving (approximately 10.5 seconds). From this point onward, the amplitude or composite result remains almost constant, meaning the process is in a steady state again until the motor spindle is completely cut off or stops after approximately 13.5 seconds.

[0175] Figure 14 It shows the relationship with the data. Figure 13 The spectrum of the synthesized result R associated with R is shown. The time axis (in t = seconds) extends from the lower right to the upper right; the frequency (in Hz) increases from the lower right to the lower left.

[0176] Here, as Figure 14 As shown, the most significant frequency is the rotational frequency f during the machining process. nII =45Hz and its multiples. The gear meshing frequency f can also be seen. ZEFII =180Hz, where this frequency is always a multiple of the rotation frequency.

[0177] Approximately 8 seconds later, another frequency appears in the spectrum, around 192 Hz, which can be interpreted as a characteristic of an unstable process or flutter (see about...). Figure 13 (The above text).

[0178] Therefore, the synthesized result R provides a convincing reflection of the processing procedure or process state. That is, instability, such as chatter in this case, can be clearly identified (by the evaluation device 202).

[0179] Another part of the algorithm then correlates these process states with machining parameters (such as material parameters) and / or user input in order to determine whether intervention is necessary for the machine tool 202 or the machining process performed by it.

[0180] Then, if necessary, another part of the algorithm uses this data to adjust these machining parameters (see above, reducing the feed until the machining process stabilizes).

[0181] Here, the evaluation unit 204 is connected to the machine tool control device 203 via a real-time channel. This allows for special adaptations / changes to machine tool feed and / or machine tool speed and / or similar parameters during machining.

[0182] A typical application here is to avoid and / or identify process errors, process instability, chatter, tool breakage, tool wear, etc.

[0183] In the event of process instability, these processing parameters are automatically and in real time changed by 160 via the machine tool control device 203.

[0184] Although the invention has been shown and described in detail through preferred embodiments, the invention is not limited to the disclosed examples, and other variations can be derived therefrom without departing from the scope of protection of the invention.

[0185] List of reference numerals in the attached diagram:

[0186] 1. Tool holder

[0187] 2 (First) Axial longitudinal end on the tool side

[0188] 3. Tool Section

[0189] 4. Tool receiving structure, tool receiving recess

[0190] 5 (Second axial longitudinal end on the connecting side)

[0191] 6 Connecting Sections

[0192] 7 Connection Structure

[0193] 8. Measuring device

[0194] 9 (Acceleration) Sensors

[0195] 10. Microcontroller (μC)

[0196] 11. Transmission equipment, antennas, SMD antennas, wired antennas

[0197] 12. Printed circuit board, circuit board

[0198] 13 (Sensor) Circuit Board

[0199] 14 Main Circuit Board

[0200] 15 (Antenna) Circuit Board

[0201] 16. Energy supply devices, voltage supply devices, batteries

[0202] 17. Settling section, circular bag-shaped section

[0203] 18. Outer surface

[0204] 19. Casting, silicone resin material

[0205] 20 (for the battery compartment) covers, lids

[0206] 21 (the circumferential direction of the tool holder (1), also referring to the outer periphery)

[0207] 22. Connecting hole

[0208] 23 (for the accelerometer) connection cable

[0209] 24 (for transmission equipment) connecting cable

[0210] 25 (for energy supply devices) connection wire

[0211] 26 (Multiple) plug-in contacts for the (accelerometer) connection wire

[0212] 27 (Multiple) plug-in contacts for (transmission equipment) connecting cables

[0213] 28 (Multiple) plug-in contacts for (energy supply devices) connecting wires

[0214] 29. Idle plug contacts

[0215] 30 Programming Contacts

[0216] 31 Axial direction

[0217] 32 Radial direction

[0218] 33 rings / annular grooves

[0219] 34 (for the annular groove) lid

[0220] 35 (Tool Holder) Base

[0221] 36. Manipulation Structure

[0222] 37 Clamping slot

[0223] 38 Central recess

[0224] 39 (Housing for (sensor) circuit board 13)

[0225] 40 (Plug-in contacts for the (accelerometer) sensor connection cable)

[0226] 41 (Plug-in type contacts for connecting wires in energy supply devices)

[0227] 42 Protective film

[0228] 43 Clamping ring

[0229] 44. Operating structure, clamping device

[0230] 45 Battery compartment

[0231] 100 methods

[0232] 110. Use at least two measurement axis signals (x, y) to form a synthesized measurement axis signal or a synthesized result R.

[0233] 120. Use the synthesized results R (for process status) for monitoring / identification / evaluation.

[0234] 130 Statistical Analysis

[0235] 140 Transformation, Coordinate Transformation

[0236] 150 Transmission (via SPI interface)

[0237] 160 Adapt / Change Working Parameters

[0238] 200 Intelligent Tool Holder

[0239] 201 CMS

[0240] 202 Machine tools, processing machines

[0241] 203 (CMS) Control / Regulation Device

[0242] 204 (CMS) Evaluation Unit

[0243] 205 Receiver

[0244] R synthesis results

[0245] D. Tool holder rotation axis, rotation axis

[0246] x-axis measurement, measurement axis signal

[0247] y-axis measurement, measurement axis signal

[0248] z-axis measurement, measurement axis signal

[0249] ZEF Central Intervention Frequency

[0250] f nII Rotation frequency

[0251] f ZEFII Tooth meshing frequency

Claims

1. A method (100) for monitoring the working characteristics of a tool holder (1), the tool holder being designed to rotate about a tool holder rotation axis (D) defining an axial direction (31), and having a tool section (3) with a tool receiving structure (4) for receiving a tool at one longitudinal end (2) of the tool holder in one axial direction, and a connecting section (6) with a connecting structure (7) at the other longitudinal end (5) of the tool holder in another axial direction, the connecting structure being used to torque-transmittingly connect with a machine tool spindle, and the tool holder having a measuring device (8) for detecting data related to the working of the tool holder (1), the measuring device (8) being an accelerometer (9) having at least two measuring axes (x, y) oriented substantially radially (32) relative to the tool holder rotation axis (D), the accelerometer providing at least two measuring axis signals (x, y) associated with the at least two measuring axes (x, y). in, Using at least two measurement axis signals (x, y) to form (110) a synthesized measurement axis signal, the synthesized measurement axis signal being the synthesis result (R), and using the synthesis result (R) to perform monitoring (120). The method also includes: Based on this monitoring, the process parameters and / or operating parameters of the machine tool (202) are adapted and / or changed in real time so that the tool holder (1) is in the machining process / machining operation.

2. The method (100) according to claim 1. Its features are, The synthesis result (R) is formed according to the following rules: R(x i ) = Sqr(Sum(x i 2 ))(1) in: Measurement axis signal of xi-axis i Sqr square root Sum (sum total) 3. The method (100) according to claim 1. Its features are, The accelerometer (9) has a third measuring axis (z) which is oriented substantially in the axial direction (31) relative to the rotation axis (D) of the tool holder. The accelerometer (9) then also provides a third measuring axis signal associated with the third measuring axis (z), and the synthesis result (R) is also formed (110) using the third measuring axis signal, and / or the third measuring axis signal is evaluated separately.

4. The method (100) according to claim 1. Its features are, The raw or processed measurement axis signals and / or data are wirelessly transmitted to the evaluation unit.

5. The method (100) according to claim 4. Its features are, This evaluation unit is a state detection system.

6. The method (100) according to claim 1. Its features are, Perform statistical processing on raw or processed measurement axis signals and / or data.

7. The method (100) according to claim 6. Its features are, The statistical treatment involves smoothing, filtering, or undergoing frequency analysis (130).

8. The method (100) according to claim 1. Its features are, Transform the original or processed measurement axis signals and / or data (140).

9. The method (100) according to claim 8. Its features are, This allows the raw or processed measurement axis signals and / or data to undergo coordinate transformation from a rotating frame to an inertial frame.

10. The method (100) according to claim 1. Its features are, Transmit (150) signals and / or data via the SPI interface.

11. The method (100) according to claim 1. Its features are, The sensor (9) is arranged in or near the rotation axis (D) of the tool holder.

12. The method (100) according to claim 1. Its features are, Based on this monitoring, the process parameters and / or operating parameters of the machine tool (202) are automatically adapted and / or changed (160) so that the tool holder (1) is in the machining process / machining operation.

13. The method (100) according to claim 1. Its features are, The tool holder (1) has a microcontroller (10), one or more transmission devices (11), one or more printed circuit boards (12, 13, 14, 15) and / or one or more power supply devices (16).

14. The method (100) according to claim 1. Its features are, The tool receiving structure (4) is a heat-shrink chuck, a hydraulic expansion chuck, a tool holder, a collet chuck, or a power chuck, and / or The connection structure (7) includes a hollow shaft cone or steep cone and / or a joint structure for a ball clamping system.

15. The method (100) according to claim 1. Use this method for: Identify the abnormal working state / process state of the tool in the tool holder (1), wherein the identification is performed by analysis using the synthetic result (R).

16. The method (100) according to claim 1. Use this method for: Identify radial runout error, where the basic load a is analyzed. zp .

17. The method (100) according to claim 1. Use this method for: Automatic machine tool control, wherein the process parameters and / or operating parameters of the machine tool (202) are automatically adapted and / or changed (160) based on the monitoring so that the tool holder (1) is in the machining process / machining operation.

18. A smart tool holder (200) having at least one tool holder (1) designed to rotate about a tool holder rotation axis (D) defining an axial direction (31), and having a tool section (3) with a tool receiving structure (4) for receiving a tool at one longitudinal end (2) of its axial direction, and a connecting section (6) with a connecting structure (7) at the other longitudinal end (5) of its axial direction, the connecting structure being used for torque-transmitting connection with a machine tool spindle, and the at least one tool holder having a function for detecting the connection between the tool holder (1) and the tool holder (200). The measuring device (8) for measuring data related to the operation of the tool holder is an accelerometer (9) having at least two measuring axes (x, y) oriented substantially radially (32) relative to the rotation axis (D) of the tool holder. The accelerometer provides at least two measuring axis signals (x, y) associated with the at least two measuring axes (x, y). The smart tool holder has an evaluation unit (204) designed to perform the method (100) according to any one of claims 1-17, which is a condition monitoring system.

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