Main shaft for machine tool

Abstract

The invention discloses a main shaft for a machine tool. The invention relates to a spindle for a machine tool, in particular for machining metal workpieces. Preferably, the main shaft is a high-speed main shaft applied to machining of metal workpieces. The spindle comprises a motor comprising a stator and a rotor arranged in a spindle housing, a clamping interface for clamping a machining tool, and a shaft of the spindle. The spindle is operatively connected to the motor, in particular the rotor is mounted on an outer surface of a shaft of the spindle. During operation of the spindle, the motor drives a shaft of the spindle for rotation. The clamping interface is mounted at one end of the shaft of the main shaft.

Description

Technical Field

[0001] The invention relates to a spindle for a machine tool. Background Art

[0002] The spindle is one of the most important components of a machine tool. The quality of the produced parts depends largely on the functionality of the spindle. Especially high-speed spindles have been widely used in machine tools. In recent years, the requirements on machine tools and main spindles related to productivity, life and reliability have increased greatly. The failure of such a spindle can lead to machining interruptions, which can directly reduce productivity and ultimately lead to economic losses. Therefore, highly reliable spindles provide a key competitive advantage for machining manufacturers and end users.

[0003] Monitoring the spindle condition is a measure to prevent dangerous situations for both the process and the final part as well as the machine, improve the quality of the output, predict the remaining life of the equipment and initiate necessary maintenance activities in a timely manner. In addition, the spindle manufacturer can obtain the operating condition of the spindle or machine tool and further improve its products and services.

[0004] US2009 / 0267429 discloses a spindle for a machine tool. The spindle has a housing for accommodating an electric motor and a shaft that can be driven by the electric motor. At least one data acquisition element is provided for recording operation and / or status data of the spindle. The data acquisition element takes the form of a radio chip and can be read by a radio device using a reading element.

[0005] However, the data analysis capabilities of monitoring devices in the prior art still need to be improved. Summary of the invention

[0006] An object is to provide a spindle for a machine tool having improved operating condition monitoring functionality. In particular, an object of the invention is to provide a spindle enabling enhanced data processing possibilities.

[0007] According to the invention, these objects are achieved by the features of the independent claims.Further advantageous embodiments emerge from the dependent claims and the description.

[0008] The present invention relates to a spindle for a machine tool, in particular a spindle for machining a metal workpiece. Preferably, the spindle is a high-speed spindle applied to machining a metal workpiece. The spindle comprises a motor comprising a stator and a rotor arranged in a spindle housing, a clamping interface for clamping a machining tool and a spindle shaft. The spindle shaft is operatively connected to the motor, in particular the rotor is mounted on the outer surface of the spindle shaft. During operation of the spindle, the motor drives the spindle shaft for rotation. The clamping interface is mounted at one end of the spindle shaft.

[0009] The spindle further includes a vibration sensing unit for detecting spindle vibration, a collision sensing unit for detecting a collision event occurring on the spindle, a tool position monitoring unit, a motor temperature sensor, a bearing temperature sensor, and a spindle diagnostic module.

[0010] The vibration sensing unit is arranged in the spindle housing. It comprises three vibration sensors for sensing the acceleration of the spindle in three linear axes. It comprises a vibration sensor circuit configured to process the sensed signals by amplification, analog-to-digital conversion and filtering, thereby generating a vibration signal. Therefore, the output signal of the vibration sensing unit is a digital signal. Preferably, the vibration sensor circuit is configured to selectively output the vibration sensor signal based on the machining conditions and / or the spindle operating conditions, in particular by adjusting the cut-off frequency of the filter used for filtering.

[0011] The collision sensing unit is arranged in the spindle housing. It includes three collision sensors for sensing the acceleration of the spindle in three linear axes, and a collision sensor circuit configured to process the sensed signals by amplification, analog-to-digital conversion and filtering to generate a collision signal. The output signal of the collision sensing unit is a digital signal. Preferably, the collision sensor circuit is configured to selectively output the collision sensor signal based on the machining conditions and / or the spindle operating conditions, in particular by adjusting the cutoff frequency of the filter used for filtering.

[0012] The tool position monitoring unit for detecting the position of the clamping interface is configured to generate a tool position signal, wherein the tool position signal is a digital signal.

[0013] The motor temperature sensor for detecting the motor temperature is arranged close to the motor and is configured to generate a motor temperature signal. In particular, the motor temperature sensor is arranged on the stator or the rotor.

[0014] A bearing temperature sensor for measuring the temperature of a bearing arranged on a bearing for supporting a shaft of a main shaft is configured to generate a bearing temperature signal. The shaft is supported by a plurality of bearings at different positions. For example, one bearing is arranged in the front of the main shaft to support the front of the shaft of the main shaft, and one bearing is arranged in the rear of the main shaft to support the rear of the shaft of the main shaft. In order to accurately monitor the temperature of each bearing, a temperature sensor is preferably arranged on each bearing to monitor the temperature change of the corresponding bearing.

[0015] The spindle diagnostic module is arranged in the spindle housing. It includes a first communication interface configured to communicate with a vibration sensing unit and a collision sensing unit, a second communication interface configured to communicate with a tool position monitoring unit, a third communication interface configured to communicate with a bearing temperature sensor, a fourth communication interface configured to communicate with an external device arranged at an outer side of the spindle, a processing unit configured to process received sensor signals, and a data storage unit configured to store received sensor signals.

[0016] The first communication interface, the second communication interface and the fourth communication interface are digital communication interfaces. In particular, the first communication interface, the second communication interface and the fourth communication interface are wireless communication.

[0017] The vibration sensing unit, the collision sensing unit and the tool position monitoring unit, the bearing temperature sensor, the motor temperature sensor and the spindle diagnostic module are mounted inside the housing of the spindle. Therefore, the sensing unit and the spindle diagnostic module have short connections for communication and the spindle does not have many external connection lines. This is advantageous for high-speed spindles. Therefore, the spindle features only one communication interface to external devices. Preferably, the spindle requires only two connections from the outside, one for power supply and one for connecting the fourth communication interface, namely Profinet. This makes it easier to install the spindle on the machine tool.

[0018] In known systems, the output signal of the sensor is usually an analog signal. Compared with analog signals, digital signals have several advantages as output signals of sensors. Because digital signals have less noise and are less prone to distortion and interference, the transmitted digital signals have better signal quality. The signal processing of digital signals is more diverse and provides higher precision. In addition, mathematical processing algorithms can be easily implemented for digital signals. This allows more specialized data analysis. In addition, digital signals enable the application of digital communication interfaces such as I2C, serial peripheral interface (SPI) and IO link.

[0019] Crash sensors are based on acceleration measurement. Acceleration sensors used in known systems are piezoelectric or piezo-ceramic sensors, which are characterized by a high dynamic range and a wide measuring range of up to ±1000g for more than 40 years. Piezoelectric sensors are mainly used in laboratory and test bench applications. Such sensors usually have a large size, which makes it impossible to integrate the sensor into the spindle. High-speed spindles can rotate at high speeds with high precision. Such spindles require a very compact design, therefore, there is only limited space inside the spindle. In addition, this type of sensor has a short lifespan and is not sensitive to temperature changes.

[0020] In the present invention, the vibration sensor and the impact sensor are micro-electromechanical systems (MEMS). This type of vibration sensor and impact sensor can detect acceleration through a micro-mechanical spring-mass system. Due to the micro technology, they are characterized by high robustness, good long-term stability and small size.

[0021] Furthermore, the application in the spindle requires a wide measuring range of acceleration values ​​up to 250g and frequencies up to 25kHz. In addition, the signal resolution should be as high as possible. However, for the application in the spindle, the acceleration sensors in the known systems have too large a dynamic range. The collision acceleration occurring in the spindle is in the range of up to 250g, and the frequency is in the range of up to 25kHz. The vibration acceleration occurring in the spindle is in the range of up to 20g, and the frequency is in the range of up to 10kHz. When the dynamic range is too large, the resolution of the signal is reduced. In the present invention, the vibration sensor and the collision sensor are custom designed. They are configured to provide sufficient dynamic range and maximum signal resolution for this application.

[0022] Both vibration sensors and crash sensors are MEMS sensors used to sense spindle acceleration. However, they are designed to sense spindle acceleration in different signal ranges with different signal resolutions. Crash sensors are designed to sense accelerations in the range of up to 250g and frequencies in the range of up to 25kHz. Vibration sensors are designed to sense accelerations occurring in the range of up to 20g and frequencies in the range of up to 10kHz.

[0023] The vibration sensor provides an electrical signal that is amplified, converted from analog to digital, and filtered by a low-pass filter to limit the bandwidth of the vibration signal. The filter cutoff frequency is variable and controlled by the spindle diagnostic module.

[0024] In a preferred variant, the processing unit of the spindle diagnostic module is configured to perform low-pass filtering and high-pass filtering of the received vibration sensor signal with a variable cut-off frequency. Preferably, the spindle diagnostic module is configured to select the sensor signal based on the machining conditions. In particular, the spindle diagnostic module is configured to select the frequency range of the sensor signal based on the machining conditions and / or the spindle operating conditions. In particular, the selection is performed by adjusting the cut-off frequency of the filter, in particular the cut-off frequency of the low-pass filter.

[0025] Applying a filter with a variable cutoff frequency makes it possible to select only the signal frequency range related to the current machining state, machining conditions and spindle operating conditions. For example, in milling, the excitation frequency generated by the cutting process depends on the spindle speed and the number of teeth of the milling cutter. Therefore, the frequency of the vibration that occurs can vary over a wide range. The vibration sensor is configured to be able to sense vibrations occurring at any frequency within the entire frequency range. When the signal frequency range of the sensor output signal can be selected, the signal frequency range can be adapted to the dominant frequency of the excitation generated by the current cutting process. Therefore, the amount of data can be reduced and the signal resolution can be improved. In particular, the vibration sensing unit and the collision sensing unit are configured so that the digital output signal has a resolution of 14 bits.

[0026] In one variation, the vibration sensing unit is configured to measure acceleration within a range of 0 to 20 g, and the impact sensing unit is configured to measure acceleration within a range of 0 to 250 g. If the impact signal is greater than a defined threshold value within a defined time interval, a collision event is indicated. Impact event data including the impact intensity and the time when the impact occurred is determined.

[0027] Preferably, the vibration sensing unit comprises three low-pass filters, each of which is configured to filter a signal detected by one vibration sensor for one linear axis. The vibration sensing unit comprises a first vibration sensor for detecting vibration in the X direction and a first low-pass filter for filtering the sensed signal. The vibration sensing unit comprises a second vibration sensor for detecting vibration in the Y direction and a second low-pass filter for filtering the sensed signal. The vibration sensing unit comprises a third vibration sensor for detecting vibration in the Z direction and a third low-pass filter for filtering the sensed signal.

[0028] The collision sensing unit includes a first collision sensor for detecting a collision in the X direction and a fourth low-pass filter for filtering the sensed signal. The collision sensing unit includes a second collision sensor for detecting a collision in the Y direction and a fifth low-pass filter for filtering the sensed signal. The collision sensing unit includes a third collision sensor for detecting a collision in the Z direction and a sixth low-pass filter for filtering the sensed signal.

[0029] In one variation, the cutoff frequencies of the first filter, the second filter, and the third filter may be adjusted and controlled by a vibration filter control signal, and the cutoff frequencies of the fourth filter, the fifth filter, and the sixth filter may be adjusted by a collision filter control signal.

[0030] For example, the cut-off frequency of the low-pass filter may be selected from one of the following frequencies: 0.5 kHz, 1 kHz, 2 kHz, 2.5 kHz, 3 kHz, 5 kHz, 10 kHz.

[0031] Since the cut-off frequency of the filter is adjustable, an appropriate frequency range of the output signal of the sensing unit can be selected. The output signal of the sensor can be optimally selected for data analysis. On the one hand, data transmission is optimized, because not all data in the entire frequency range are transmitted, but only the required data in a specified frequency range are transmitted. On the other hand, data analysis can be performed more accurately, because more data in the frequency range of interest can be transmitted and thus can be used for data processing.

[0032] Preferably, the vibration filter control signal and the collision filter control signal can be sent by the spindle diagnostic module to the vibration sensor and the collision sensor respectively. In particular, the vibration filter control signal and the collision filter control signal are generated by a processing unit of the spindle diagnostic module.

[0033] By providing adjustable filters, large signal frequencies can be covered without compromising signal resolution. Different frequency and acceleration ranges for the spindle can be selected. This enables more accurate analysis and precise collision detection. In addition, precise analysis of the vibration signal enables monitoring and characterization of machining conditions to optimize machining parameters in order to achieve the best possible surface finish, increase productivity and extend the life of the cutting tool. It also enables condition monitoring of the spindle to extend its service life.

[0034] In particular, the processing unit of the spindle diagnostic module is configured to perform an axis transformation of the vibration sensor axis and / or the impact sensor axis to the spindle axis. This step allows the sensed values ​​to be assigned to the corresponding axis of the spindle.

[0035] In a preferred variation, the first communication interface is a serial peripheral interface (SPI) directly connected to the collision sensing unit and the vibration sensing unit, which is configured to transmit the vibration signal and the collision signal to the spindle diagnostic module. SPI is a synchronous bus for high-speed digital devices. For example, the transmission rate is in the range of 4Mbps to 7Mbps.

[0036] Preferably, the vibration sensing unit, the impact sensing unit is embedded in the same housing defined as the vibration impact sensing unit housing. This device is rigidly fixed in the front part of the main shaft, in particular on a flange located near the front bearing located in the front part of the shaft for supporting the main shaft. Mounting the device at this position ensures that the accelerations on the different axes can be optimally sensed by the sensor.

[0037] In particular, the sensor housing is fixed to a non-rotating element of the spindle positioned in the front part of the spindle. It is important to fix the sensor housing with the vibration sensing unit and the impact sensing unit therein in the spindle in a rigid manner to obtain reliable sensing signals. Therefore, the sensor housing is preferably glued at a position close to the bearing in the front part of the spindle. In addition, the sensor housing is positioned in a defined direction so that the vibration sensor and the impact sensor are oriented in a predetermined direction by considering the axial direction of the spindle to obtain an optimal sensor signal.

[0038] In one variant, the tool position monitoring sensor measures the tool position based on inductive measurements. In particular, it measures the position of the clamping interface. The measuring range is 0 to 15 mm.

[0039] In some embodiments, the second communication interface is an IO link, in particular, an IO master device is included in the spindle diagnostic module, and the tool position monitoring sensing unit is an IO slave device. IO link is a communication standard for connecting digital sensors to a communication bus (such as an industrial field bus or industrial Ethernet). The IO link includes an IO master device and one or more IO link devices. The IO link can be wired or wireless. The digital output of the tool position monitoring sensor makes it possible to communicate the sensor signal with the spindle diagnostic module via the IO link.

[0040] In some embodiments, four temperature sensors are provided, and each temperature sensor is arranged on a bearing to measure the temperature of the corresponding bearing. In this way, the temperature of all bearings can be monitored and analyzed.

[0041] In one variation, an axis motion sensor is provided for measuring the motion of the axis.

[0042] In a variant, the fourth communication interface is Profinet. This digital interface opens up new possibilities in the field of monitoring and transmitting real-time data, which allows the analysis process to be carried out in a more accurate manner. Profinet allows fast and flexible communication.

[0043] In particular, the data storage unit of the spindle diagnostic module is configured to store, in addition to the sensor signals, the spindle operating data describing the spindle operating conditions, such as the spindle operating hours, the spindle rotation speed and data logger, the spindle serial number, the spindle identification number, the maximum number of spindle rotations, the number of machine tool changes. In addition, the data storage unit is configured to store at least one hundred collision events.

[0044] Furthermore, the processing unit of the spindle diagnostic module is configured to analyze digital vibration signals and digital collision signals, in particular to analyze the signals in the frequency domain. Furthermore, processing data of the machine tool representing the processing conditions can be transmitted to the spindle and stored in the storage device of the spindle diagnostic module. The processing data includes processing parameters such as cutting speed, feed speed, and information related to the processing tool. In particular, the processing data of the machine tool transmitted to the spindle diagnostic module is stored and processed only within the spindle diagnostic module. This data will remain in the spindle diagnostic module and cannot be further transmitted from the spindle diagnostic module to any other device.

[0045] In a preferred variant, the processing unit of the spindle diagnostic module is configured to send vibration signals and / or collision signals to an external device at regular time periods for diagnosing bearing quality. In addition, this data can be used for other data analysis, such as fast Fourier transform.

[0046] Preferably, the vibration signal and the collision signal are not stored in the spindle diagnosis module to save the storage capacity of the spindle diagnosis module.

[0047] In a variant, the external device can send a request signal to the spindle diagnostic module. According to this request, the spindle diagnostic module starts to transmit the collision signal and the vibration signal to the external device via Profinet.

[0048] Alternatively, the User Datagram Protocol (UDP) is applied. The streaming transmission of real-time data via UDP allows real-time data analysis. In addition, the Transmission Control Protocol (TCP) or the Stream Control Transmission Protocol (SCTP) can also be applied. In this way, the signal processing is not limited by the storage capacity of the spindle diagnostic module. Therefore, more complex data analysis is possible, because this can be performed in an external processing unit arranged outside the spindle. In this mode, the sensor signal is transmitted only within a limited period to avoid communication overload.

[0049] The present invention is directed to a machine tool including a machine table for mounting a workpiece thereon and a machine head for mounting the spindle of the present invention therein.

[0050] Furthermore, the machine tool comprises a control unit configured to control machining. The control unit is configured to communicate with the spindle diagnostic module via a digital communication interface, in particular Profinet.

[0051] In one embodiment, a control unit of a machine tool is configured to receive vibration signals and collision signals and implement anomaly detection for detecting defects of a spindle. Artificial intelligence algorithms are applied to anomaly detection. In particular, main component analysis is applied.

[0052] In a variant, the sensor data received from the sensing unit integrated in the spindle and stored in the diagnostic module are transmitted to the control unit and displayed on a display of the machine tool, in particular a large number of collision events can be displayed. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In the following, a more specific description of the present invention is further described. Embodiments are described and explained in detail with reference to the accompanying drawings, in which: Figure 1 illustrates a simplified cross-sectional view of a spindle for a machine tool; and Figure 2 A schematic diagram illustrating the communication between the sensor and the machine tool is shown; DETAILED DESCRIPTION

[0054] Figure 1 A cross-sectional view of a spindle 1 for a machine tool is shown. The spindle comprises a spindle shaft 6 and a clamping interface 5 mounted at the front end of the spindle shaft. The shaft is driven by a motor comprising a rotor 3 and a stator 4. The rotor is arranged on the outer surface of the shaft and is surrounded by the stator. A first bearing and a second bearing are arranged on the front of the spindle, while a third bearing and a fourth bearing are arranged on the rear of the spindle. A bearing temperature sensor is mounted on each bearing to measure the temperature of the corresponding bearing. Figure 1 The components relevant to the present invention are shown. Therefore, not all components of the spindle are depicted. The arrangement of sensors and spindle diagnostic modules can also be applied to spindles having different Figure 1 The main axis of the structure of the main axis shown in the figure.

[0055] The vibration sensing unit and the collision sensing unit are integrated in a vibration collision sensing unit housing 10 and are fixedly mounted on the flange of the spindle in a rigid manner. The sensor housing has a cubic shape and a small size of 21×15×18.3 mm. Due to the limited space inside the spindle, a smaller sensing unit can easily integrate the sensor at an optimal position with a defined direction according to the axis of the spindle. The tool position monitoring unit 20 is arranged in the rear of the spindle. The motor temperature sensor 30 for measuring the motor temperature is arranged on the stator 4. The first bearing temperature sensor 31 and the second bearing temperature sensor 32 are arranged on the front of the spindle, especially on the first front bearing and the second front bearing of the spindle. The third bearing temperature sensor 33 and the fourth bearing temperature sensor 34 are arranged in the rear of the spindle, especially on the third rear bearing and the fourth rear bearing of the spindle. The spindle diagnostic module 60 is arranged in the rear of the spindle and is completely embedded in the interior of the spindle housing. The power connector 62 for powering the spindle diagnostic module, the sensing unit and the communication interface connector 61 is installed at the end of the spindle.

[0056] Figure 2The communication connections within the spindle and between the spindle and the machine tool 100 are shown. Figure 2 An example of how the spindle communicates with the control unit 102 of the machine tool is shown. The vibration sensing unit and the collision sensing unit are configured to communicate with the spindle diagnostic module via the SPI communication interface. The tool position monitoring unit (TPM) 20 is configured to communicate with the spindle diagnostic module via the IO link. Additional sensors can also be integrated in the spindle. The temperature sensor signals of the four bearing temperature sensors for sensing the bearing temperature are directly fed to the spindle diagnostic module.

[0057] The spindle motor is controlled by the machine tool's control unit 100. The measured motor temperature can be transmitted to a spindle diagnostic module or directly to the machine tool's control unit, as shown in this figure.

[0058] The power supply unit 70 is arranged outside the spindle, for example, Figure 2 The machine tool shown in the figure supplies power to the spindle diagnostic module. The spindle diagnostic module can transmit all data received from the sensing unit to the control unit via Profinet. In addition, the control unit of the machine tool can also transmit data to the spindle via Profinet. Figure 2 A variant is shown in which the communication module 101 is integrated in the machine tool. Profinet is directly connected to the communication module, which in turn is connected to the control unit of the machine tool.

[0059] Reference List 1 Spindle 2-axis 3 rotors 4 Stator 5 Clamping interface 6-axis 10Vibration unit and impact sensor unit 20 Tool position monitoring unit 30 Motor temperature sensor 31 First bearing temperature sensor 32 Second bearing temperature sensor 33 Third bearing temperature sensor 34 Fourth bearing temperature sensor 40 encoder speed position sensor 60 spindle diagnostic module 61 Communication interface connector 62 Power Connector 70 Power Supply Unit 100 Machine Tools 101 Communication Module 102 control unit.

Claims

1. A spindle (1) for a machine tool, in particular for machining a metal workpiece, comprising: a. a motor comprising a stator and a rotor arranged in a spindle housing; b. a spindle shaft operatively connected to the motor, in particular, the rotor is mounted on the outer surface of the spindle shaft, wherein during operation of the spindle, the motor drives the spindle shaft for rotation; c. a clamping interface for clamping a machining tool, wherein the clamping interface is arranged at one end of the spindle shaft; d. a vibration sensing unit (10) for detecting vibration of the spindle arranged in the spindle housing, the vibration sensing unit comprising three vibration sensors for sensing acceleration of the spindle on three linear axes, and a vibration sensor circuit configured to process the sensed signals by amplification, analog-to-digital conversion and filtering to generate a vibration signal; e. a collision sensing unit (10) for detecting a collision event occurring on the spindle arranged in the spindle housing, the collision sensing unit comprising three collision sensors for sensing acceleration of the spindle in three linear axes, and a collision sensor circuit configured to process the sensed signals by amplification, analog-to-digital conversion and filtering to generate a collision signal; f. a tool position monitoring unit (20) for detecting the position of the clamping interface, the tool position monitoring unit being configured to generate a tool position signal, wherein the tool position signal is a digital signal; g. a motor temperature sensor for measuring the temperature of the motor, wherein the motor temperature sensor is arranged close to the motor, in particular on the stator, and the motor temperature sensor is configured to generate a motor temperature signal; h. a bearing temperature sensor for measuring the temperature of the bearing arranged on a bearing of a shaft supporting the main shaft, the bearing temperature sensor being configured to generate a bearing temperature signal; as well as i. A spindle diagnostic module (60) is arranged in the spindle housing, comprising a first communication interface configured to communicate with the vibration sensing unit and the collision sensing unit, a second communication interface configured to communicate with the tool position monitoring unit, a third communication interface configured to communicate with the bearing temperature sensor, a fourth communication interface configured to communicate with an external device arranged at the outside of the spindle, a processing unit configured to process received sensor signals, and a data storage unit configured to store received sensor signals.

2. The spindle according to claim 1, wherein: The first communication interface is a serial peripheral interface directly connected to the collision sensing unit and the vibration sensing unit, and the serial peripheral interface is configured to transmit the vibration signal and the collision signal to the spindle diagnostic module.

3. The spindle according to claim 2, wherein: The vibration sensing unit and the impact sensing unit are embedded in the same housing defined as a vibration-impact sensing unit housing, which is rigidly fixed to the front of the spindle, particularly to a flange located near the front bearing of the front of the shaft supporting the spindle.

4. The spindle according to claim 1, wherein: The vibration sensor and the impact sensor are micro-electromechanical system based sensors.

5. The spindle according to claim 1, wherein: The vibration sensor circuit is configured to filter the sensed signal using a variable cutoff frequency controlled by the spindle diagnostic module.

6. The spindle according to claim 1, wherein: The crash sensor circuit is configured to filter the sensed signal using a variable cutoff frequency controlled by the spindle diagnostic module.

7. The spindle according to claim 1, wherein: The processing unit of the spindle diagnostics is configured to perform an axis transformation of the vibration sensor axis and / or the impact sensor axis to the spindle axis.

8. The spindle according to claim 1, wherein: The processing unit of the spindle diagnostics is configured to perform low pass filtering with a variable cutoff frequency and high pass filtering of the vibration sensor signal.

9. The spindle according to claim 1, wherein: The processing unit of the spindle diagnosis is configured to send the vibration signal and / or the collision signal to an external device at a regular time period for diagnosing the bearing quality.

10. The spindle according to one of claims 1 to 9, wherein The second communication interface is an I / O link, in particular, an I / O master device is included in the spindle diagnostic module, and the tool position monitoring sensing unit is an I / O slave device.

11. The spindle according to one of claims 1 to 10, wherein The tool position monitoring sensor is configured to measure the tool position based on inductive measurements.

12. The spindle according to one of claims 1 to 11, wherein Four bearing temperature sensors are provided, and each bearing temperature sensor is arranged on one bearing for measuring the temperature of the corresponding bearing.

13. The spindle according to one of claims 1 to 12, wherein The fourth communication interface is Profinet.

14. A machine tool comprising a spindle according to one of claims 1 to 13, wherein: The machine tool comprises a control unit configured to control the machine tool, and the spindle diagnostic module is configured to communicate with the control unit via the fourth communication interface.

15. The machine tool according to claim 15, wherein: The control unit is configured to transmit machining parameters to the spindle diagnostic module via the Profinet.

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