CN116723912A - Monitoring system for movable assembly connected to fixed part - Google Patents
Monitoring system for movable assembly connected to fixed part Download PDFInfo
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- CN116723912A CN116723912A CN202180085350.0A CN202180085350A CN116723912A CN 116723912 A CN116723912 A CN 116723912A CN 202180085350 A CN202180085350 A CN 202180085350A CN 116723912 A CN116723912 A CN 116723912A
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 71
- 238000012545 processing Methods 0.000 claims abstract description 63
- 238000004891 communication Methods 0.000 claims abstract description 28
- 238000000034 method Methods 0.000 claims abstract description 28
- 230000008569 process Effects 0.000 claims abstract description 20
- 230000005540 biological transmission Effects 0.000 claims description 14
- 238000010168 coupling process Methods 0.000 claims description 11
- 238000005859 coupling reaction Methods 0.000 claims description 11
- 238000005259 measurement Methods 0.000 claims description 6
- 238000004378 air conditioning Methods 0.000 claims 5
- 230000001934 delay Effects 0.000 claims 1
- 238000005309 stochastic process Methods 0.000 claims 1
- 230000008878 coupling Effects 0.000 description 7
- 238000007689 inspection Methods 0.000 description 4
- 230000006870 function Effects 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 2
- 230000002853 ongoing effect Effects 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000013139 quantization Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B23/00—Testing or monitoring of control systems or parts thereof
- G05B23/02—Electric testing or monitoring
- G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
- G05B23/0208—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterized by the configuration of the monitoring system
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/10—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving electrical means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/12—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving optical means
Abstract
A monitoring system (12) for a movable part (3), such as a rotating part, is supported by a stationary part (2). The monitoring system (12) comprises: an acoustic sensor (10) located in the movable part (3); a first amplifier (18) located in the movable part (3); a contactless communication unit (14) provided with a first transceiver means (15) located in the movable part (3), and a second transceiver means (16) facing the first transceiver means (15) and placed in the fixed part (2); a first connection line (19) connecting the acoustic sensor (10) to the first amplifier (18); an analog-to-digital converter (37) disposed in the movable member (3) or the fixed member (2) and configured to receive an analog signal and convert the analog signal into a digital signal; and a processing device (38) placed in the movable part (3) or the fixed part (2) and configured to receive the digital signal from the analog-to-digital converter (37) to process the digital signal and obtain and output a processed digital signal.
Description
Technical Field
The present invention relates to a monitoring system for a movable part (e.g. a rotating part) connected to a stationary part.
The invention can be advantageously applied to monitoring systems using acoustic signals for supporting the rotating spindle of (at least) a grinding wheel in a machine tool, to which the following discussion will make explicit reference without loss of generality.
Background
It is known, for example, from patent applications EP0690979A1, EP1870198A1 and EP3134980A1, for a rotating spindle (hub) of a machine tool, in particular a grinding machine, to support (at least) a grinding wheel and to have a balancing head accommodated in an axial cavity. The balance head comprises at least one balance block eccentric relative to the rotating shaft, and the position of the balance block can be adjusted and controlled by the motor.
Typically, the balance head also includes a vibration sensor (i.e., a microphone) for detecting ultrasonic emissions due to contact of the grinding wheel with the workpiece or the grinding wheel with the dressing tool (dresser). The electrical signal generated by the vibration sensor is used (in a known manner) to control the machining cycle.
The microphone is part of a monitoring system in which the electrical signal provided by the microphone is processed to provide information about the correctness of the process. The control unit of the machine tool can then act on the process based on such information.
Disclosure of Invention
The object of the present invention is to provide a monitoring system for a movable part connected to a fixed part, which allows to detect in an accurate and stable way the effects of ongoing actions, such as the machining of a workpiece or the dressing of a grinding wheel, preferably easy to install even in confined spaces.
The present invention provides a monitoring system for a movable part connected to a fixed part, as defined in the appended claims.
The claims describe embodiments of the invention and form an integral part of the present description.
Drawings
The invention will be described with reference to the accompanying drawings, which illustrate non-limiting examples of embodiments, in which:
FIG. 1 schematically illustrates a machine tool having a rotating spindle that supports a grinding wheel and has a balance head;
fig. 2 schematically shows a monitoring system according to the invention; and
fig. 3-7 are a series of schematic diagrams of alternative embodiments of the monitoring system of fig. 2.
Detailed Description
In fig. 1, reference numeral 1 denotes a machine tool (in particular, a grinding machine) as a whole, only some of which are shown.
Typically, a machine tool comprises a fixed part or fixed component and a movable part or movable component that are connected to each other. In grinding machines, the movable part is usually rotated relative to the fixed part.
The machine tool 1 shown in fig. 1 includes a frame 2 (i.e., a fixed portion) that rotatably supports (by disposing a bearing therebetween) a spindle 3 that rotates about a rotation axis 4.
The spindle 3 supports a grinding wheel 5 by means of a corresponding grinding wheel hub which is detachably secured to the spindle 3 by means which are known and not shown, including, for example, a conical coupling. The spindle 3 and the grinding wheel hub define a rotating part of the machine tool 1, also called rotor. The spindle 3 has an axial opening 6 in the centre which accommodates a balancing head 7. The balancing head 7 of known type comprises two balancing weights 8 eccentric with respect to the rotation axis 4 and respective motors 9 for adjusting the angular position of the balancing weights 8. The rotating part further comprises (at least) an acoustic sensor 10 or a vibration sensor. In fig. 1, the acoustic sensor 10 is integrated into the balance head 7, but may also be not integrated into the balance head 7 and arranged in a different region of the rotating component, for example as shown in fig. 2.
The balancing head 7 serves to balance the grinding wheel 5. This is generally done when the grinding wheel 5 is replaced and when it is required due to the abrasion of the grinding wheel 5.
The balancing head 7 comprises control means 11 which control the operation of the balancing head 7.
The balance head 7 described and shown in the figures may not be present and the rotating part comprises only the acoustic sensor 10 or the acoustic sensors.
The acoustic sensor 10 and the balance head 7 (if provided) are part of a monitoring system 12, the monitoring system 12 being connected to a processing unit 40 arranged in a fixed position, i.e. supported by the frame 2 of the machine tool 1. The monitoring system 12 is configured to provide a signal to a processing unit 40 mounted on the frame 2 (i.e. in a fixed part of the machine tool 1) related to vibrations to which the spindle 3 (i.e. an assembly of rotating parts of the machine tool 1) is subjected to at the grinding wheel 5.
Fig. 2-6 show a monitoring system 12, in which the acoustic sensor 10, unlike the embodiment of fig. 1, is not integrated into the balance head 7.
The dashed boxes in the figure represent the physical division of the rotating and stationary parts of the machine tool; the configuration of the individual components of the monitoring system 12 may vary from that shown in the figures.
As shown in fig. 2, the monitoring system 12 comprises a contactless communication unit 14 with a first transceiver device 15 located in the spindle 3 (i.e. in the rotating part of the machine tool 1) and a second transceiver device 16 facing the transceiver device 15 and located in the frame 2 (i.e. in the stationary part of the machine tool 1). The two transceiver means 15 and 16 are adapted to communicate with each other in a contactless and known manner in order to send information from the transceiver means 15 to the transceiver means 16 and vice versa. The fixed part comprises an interface unit 13 which distributes power to the components of the monitoring system 12 and transmits signals leaving or entering the processing unit 40.
The communication unit 14 is used by the interface unit 13 in one direction to send control signals (for example to activate/deactivate the readings of the acoustic sensor 10 or to control the motor 9 that moves the counterweight 8 of the balance head 7) from the processing unit 40 and/or from a control unit (not shown in the figures) of the machine tool, and in the opposite direction to transmit diagnostic signals (generated in the balance head 7) to the interface unit 13 and/or signals related to vibrations to which the spindle is subjected.
As shown in fig. 2, the acoustic sensor 10 includes two terminals 17 between which a variable voltage (i.e., an analog signal) is generated, depending on the intensity and frequency of the vibrations detected by the vibration sensor 10 itself.
The monitoring system 12 comprises an amplifier 18 placed inside the rotor (i.e. in the rotating part of the machine tool 1) and comprising two input terminals and two output terminals.
The monitoring system 12 comprises a first connection line 19 connecting the acoustic sensor 10 to the amplifier 18 and comprising two separate (i.e. electrically insulated) electrical leads, each connecting a terminal 17 of the vibration sensor 10 to a corresponding input terminal of the amplifier 18.
The monitoring system 12 comprises a second connection line 20 connecting the amplifier 18 to the transceiver device 15 and comprising two separate (i.e. electrically insulated) electrical leads, each connecting an output terminal of the amplifier 18 to the transceiver device 15.
In particular, the amplifier 18 is disposed proximate to the acoustic sensor 10.
In the embodiment shown in fig. 1, in which the acoustic sensor 10 is integrated into the balance head 7, the amplifier 18 can be positioned in the control device 11 of the balance head 7 or integrated into the acoustic sensor 10. The connection line 20 is integrated into the multipolar cable 21, preferably coiled, which extends along the axial opening 6 and comprises, in addition to the connection line 20, one or more electric power lines (i.e. lines transmitting electric power for operating the balancing head 7).
In the embodiment shown in fig. 2, the communication unit 14 transmits analog signals in a contactless manner by means of inductive coupling. According to a different embodiment (not shown), the communication unit 14 transmits the analog signal in a contactless manner by means of an optical coupling (for example according to one of the alternatives described in patent No. US 5688160A). The transceiver device 15 receives the voltage and current that vary according to the vibrations detected by the acoustic sensor 10 and transmits (senses) the corresponding voltage and corresponding current by inductively coupling to the transceiver device 16. Thus, an analog signal of electronic type leaves the transceiver device 16. Preferably, the monitoring system 12 comprises an amplifier 22 located in the frame 2 (i.e. in the fixed part of the machine tool 1) and comprising two input terminals, connected to the transceiver device 16 and to two outputs of the interface unit 13, the interface unit 13 being configured to process the signals generated by the acoustic sensor 10, as previously described.
The monitoring system 12 comprises a power supply circuit 23 with a first power supply device 24, the first power supply device 24 being located in the rotor (i.e. in the rotating part of the machine tool 1) and providing power to the amplifier 18, and with a second power supply device 25 being located in the machine frame 2 (i.e. in the stationary part of the machine tool 1), providing power to the amplifier 22 and the power supply device 24, and receiving power from the interface unit 13. Due to the presence of the amplifiers 18 and 22 (which have to provide power), the signal conditioning is improved and more powerful than in the case of a direct connection between the acoustic sensor 10 and the transceiver device 15. Further, the power supply circuit 23 includes an air-coupled transformer 26 having a first coil 27, the first coil 27 being located in the rotor (i.e., in the rotating part of the machine tool 1) and supplying power to the power supply device 24, and a second coil 28 being located in the frame 2 (i.e., in the stationary part of the machine tool 1) and receiving power from the power supply device 25. In the embodiment shown in fig. 2, the power supply device 24 is directly connected to the coil 27 of the air-coupled transformer 26; that is, the power supply device 24 receives power directly from the coil 27 of the air-coupled transformer 26 without a medium.
Fig. 2 also shows a further power supply circuit 29, which is completely separate and independent from the power supply circuit 23 of the monitoring system 12 and supplies power to the balancing head 7. When the balance head 7 is present, the power supply circuit 29 is present. The power supply circuit 29 includes, for example, a power supply device 30 that is located in the rotor (i.e., in the rotating part of the machine tool 1) and supplies power to the balance head 7, and a power supply device 31 that is located in the frame 2 (i.e., the stationary part of the machine tool 1), supplies power to the power supply device 30 through an air-coupling transformer 32, and receives power from the interface unit 13.
In the embodiment shown in fig. 2-5, the balancing head 7 is powered by a power circuit 29, which power circuit 29 supplies only power to the balancing head 7 and is independent of the power circuit 23 of the monitoring system 12. In the embodiment shown in fig. 6, only the power supply circuit 23 is provided and shared by the entire monitoring system 12 including the balance head 7. In other words, the power supply circuit 23 also supplies power to the balance head 7.
In the alternative embodiment shown in fig. 3, the monitoring system 12 comprises a further amplifier 33, which is located in the rotor (i.e. in the rotating part of the machine tool 1), is connected in series to the amplifier 18 along the connection line 20, and comprises two inputs, two outputs and two outputs connected to the amplifier 18, and is connected to the transceiver device 15. In particular, the amplifier 18 is arranged near (near) the vibration sensor 10 (i.e., at the beginning of the connection line 20 with reference to the layout shown in the drawing), while the amplifier 33 is arranged near (near) the transceiver device 15 (i.e., at the end of the connection line 20 with reference to the layout shown in the drawing).
In the embodiment shown in fig. 3, the amplifier 33 is also powered by the power supply means 24, which power supply means 24 power the amplifier 18.
In an alternative embodiment shown in fig. 4, the monitoring system 12 comprises a third power supply device 34 directly connected to the coil 27 of the air-coupled transformer 26; in other words, the power supply device 4 receives power directly from the coil 27 of the air-coupled transformer 26 without a medium. Furthermore, the monitoring system 12 comprises coupling means 35 which receive power from the power supply means 34 and feed it to the connection line 20 in a frequency band different from that of the analog signal generated by the acoustic sensor 10, and decoupling means 36 which take power from the connection line 20 and supply it to the power supply means 24 (which thus indirectly receive power from the coil 27 of the air-coupled transformer 26). For example, coupling means 35 and decoupling means 36 use reactive components to achieve frequency band separation and transmit continuous or alternating power having a higher or lower frequency than the analog signal generated by acoustic sensor 10, which typically has a frequency between 1KHz and 1 MHz.
In the embodiment shown in fig. 2-4, the communication unit 14 transmits analog signals (to be digitized in the processing unit 40) between the two transceiver devices 15 and 16. In the embodiment shown in fig. 5-7, the communication unit 14 transmits digital signals between two transceiver devices 15 and 16. The monitoring system 12 actually comprises an analogue-to-digital converter 37 located in the rotor (i.e. in the rotating part of the machine tool 1) and configured to receive the analogue signal from the amplifier 18 (together with the amplifier 33 if provided) and to convert the analogue signal into a digital signal.
Furthermore, the monitoring system 12 preferably comprises processing means 38, positioned in the rotor (i.e. in the rotating part of the machine tool 1) and configured to receive the digital signal from the analog-to-digital converter 37, to process the digital signal and obtain a processed digital signal, and to provide the processed digital signal to the transceiver means 15.
More specifically, the processing means 38 performs time-domain and frequency-domain processing on the digital signal leaving the analog-to-digital converter 37. Preferably, the processing is based on the computation of a fourier transform.
More specifically, the processing is performed by using a Fast Fourier Transform (FFT).
For example, the signal processing may include the steps of:
-selecting a frequency band of the signal and setting a gain;
-sampling the signal at a frequency higher than 2MHz;
-calculating an FFT function;
-zeroing in the frequency domain;
demodulating the signal spectrum to perform an inspection related to the gap (i.e. the distance between the grinding wheel and the workpiece or the dressing tool) and an inspection related to the collision, i.e. the contact between the grinding wheel and the workpiece or other component of the dressing tool or machine tool, demodulating the two types of inspection independently;
-performing a time domain processing of the signal for each of two types of examination independent of each other;
triggering an automatic execution of the parameterization of the frequency band and of the signal gain and triggering a return to zero of the background noise.
Optionally, the background noise may also be zeroed based on its average or maximum value.
Processing the coarse signal, i.e. the signal generated by the acoustic sensor 10, inside the rotor allows to perform the complete signal processing (e.g. comprising the steps described before) as close as possible to the signal source, i.e. the acoustic sensor 10, and significantly shortens the propagation path of the coarse signal.
In known solutions, the analog signal generated by the sensor is transmitted to an external processor, which converts the analog signal into a digital signal, which is then processed. The processor is typically located in a corporate lab or laboratory controller and performs processing operations without adhering to strict constraints. However, since the propagation path of an analog signal may be long, the signal-to-noise ratio is often deteriorated and the signal quality reaching the processor is significantly deteriorated.
According to known solutions, the signals generated by the sensors are digitized in the vicinity of the sensors and then transmitted to an external processor for complete processing. However, the bandwidth required for transmitting digital signals is too large for contactless communication systems in industrial applications. This problem has been overcome in known solutions by obtaining the digital signal by quantization with a relatively differential state (e.g. 8 bits) and performing only a minimum of digital processing before transmitting it. In this way, the bandwidth of the signal to be transmitted is limited, but the poor digital processing that has been performed before the signal transmission results in unavoidable low-performance signal processing in the external processor.
The monitoring system 12 according to the invention allows to convert, in particular fully process, the signals generated by the acoustic sensor 10 in close proximity to such sensor, i.e. highly miniaturized, very low energy consumption and low bandwidth transmission of detailed information about the process monitoring, by simultaneously satisfying the requirements of such applications.
This is achieved by combining processing means with low computational power with highly optimized software algorithms. In fact, the hardware of the processing device is designed with lower computational power than the devices commonly used in such applications, to reduce overall size and power consumption, while the software is designed in such a way as to perform all the operations required for monitoring, but with less resources.
According to a preferred embodiment of the invention, in order to obtain a processed digital signal inside the rotor and to send the processed digital signal through the contactless communication unit 14, the monitoring system 12, more specifically the analog-to-digital converter 37 and the processing means 38, a method is implemented comprising the steps of:
increasing the analog-digital acquisition dynamics by using SAR (successive approximation buffer) converters with higher resolution than known solutions.
Performing a high frequency acquisition of the coarse fundamental frequency signal generated by the acoustic sensor 10, said frequency being higher than 2Mhz.
-performing a random process on the single measurement, the random process being highly parameterizable to maintain high efficiency when the monitored process changes. More specifically, the digital stochastic processing technique used ensures stability and convergence.
-implementing an automatic parameter setting mode allowing automatic parameterization of the process based on observations of the monitored process. The parameters of the process produce acoustic emissions that are detected and monitored by acoustic sensors, which are not known a priori (priori) because they depend on many operating and environmental conditions. The automatic parameter setting mode implemented is defined based on one or more learning phases and subsequent processing of the obtained results.
-encapsulating the processing result, i.e. the processed digital signal, for transmitting real-time information of the high priority and low priority information on the same communication channel. As previously described, digital processing techniques produce large amounts of data and therefore require large bandwidths to transmit signals. The encapsulation of the processed digital signal is performed according to an optimized communication protocol that allows defining the hierarchical structure of the information according to the delay of the usage information. This makes it possible to transmit the processed digital signal via a contactless communication channel as provided in the monitoring system according to the invention.
Preferably, the above method further comprises the step of performing a specific process of a plurality of simultaneous measurements based on the same coarse signal without the need of adding dedicated hardware. Machine tool applications using acoustic sensors typically perform at least two measurements: measurements related to machine operation, with higher sensitivity and narrower frequency bands to track the machine process with maximum accuracy, and monitored measurements with lower sensitivity and wider frequency bands to identify anomalies even outside the typical process frequency band in time.
The combined use of hardware and software designed as described above allows for a complete processing of the signal generated by the acoustic sensor 10 inside the rotor, which means that the signal processing is not only of good quality and good signal-to-noise ratio, but has not been partially processed beforehand, thus risking a loss of information.
In the embodiment of fig. 5, transceiver device 15, analog-to-digital converter 37 and processing device 38 receive power from power supply device 34, while transceiver device 16 receives power from power supply device 25.
The only difference between the embodiment shown in fig. 5 and the embodiment shown in fig. 6 is that in the embodiment shown in fig. 5 the power supply circuit 29 supplying power to the balancing head 7 is separate and independent from the power supply circuit 23, whereas in the embodiment shown in fig. 6 only the power supply circuit 23 is provided and shared by the entire monitoring system 12 comprising the balancing head 7 (in other words, the power supply circuit 23 also supplies power to the balancing head 7).
According to a different embodiment not shown in the figures, the analog-to-digital converter 37 and the processing means 38 are arranged in the machine frame 2 (i.e. in a fixed part of the machine tool 1). The conversion of analog signals into digital signals and their processing is not carried out in the rotating part of the machine tool, but in the stationary part of the machine tool. This solution can be applied to the alternative embodiments of the monitoring system 12 shown in fig. 5, 6 and 7.
In the embodiment shown in fig. 7, the monitoring system 12 comprises two acoustic sensors 10, two amplifiers 18 separate and independent from each other, and two connection lines 19, each connecting one of the acoustic sensors 10 to the amplifier 18 and comprising two independent electrical leads. Furthermore, the monitoring system 12 comprises a single communication unit 14 (which is shared between the two acoustic sensors 10), and a multiplexer 39 having two inputs connected to the two amplifiers 18 and a single output of the transceiver device 15 connected to the single communication unit 14. Multiplexer 39 is an input selector that receives several analog input signals and sends them alternately to a single output. The multiplexer 39 allows having a plurality of sensors located in different areas of the rotor and selects the signal from the most effective sensor for monitoring purposes depending on the operation performed through the machine tool.
It is clear that both the two (or more) acoustic sensors 10 and thus the multiplexer 39 may be present when a single communication unit 14 transmits a digital signal (as shown in fig. 7) and when a single communication unit 14 transmits an analog signal, i.e. when the monitoring system 12 does not comprise an analog-to-digital converter 37. Furthermore, when a power supply 34 is provided for powering each power supply device 24 using the coupling device 35 and the decoupling device 36, and when each power supply device 24 is directly connected to the windings 27 of the air-coupling transformer 26, there may be two (or more) vibration sensors 10 and thus a multiplexer 39 (as shown in fig. 7).
According to a possible embodiment, the processing means 38 control the multiplexer 39 to control which acoustic sensor 10 has to provide signals to the transceiver means 15 of the single communication unit 14, i.e. which acoustic sensor 10 has to be read. The multiplexer 39 may be statically assigned or, alternatively, dynamically configured, i.e. connects each input to an output in a cyclic and alternating manner at a defined switching frequency. The multiplexer 39 can be controlled by the processing device 38 both when the processing device 38 is arranged in the rotor (as shown in fig. 7) and when it is arranged in a stationary part of the machine tool.
In the embodiment shown in fig. 7, two acoustic sensors 10 are provided, connected to a multiplexer 39 (via respective amplifiers 18). According to other embodiments not shown in the figures, three or more acoustic sensors 10 are provided, connected to a multiplexer 39 (through respective amplifiers 18); all or some of these sensors cannot be acoustic sensors.
The presence of a plurality of acoustic sensors and multiplexers has been shown and described so far with reference to the monitoring system 12, wherein the signal processing takes place in either the stationary or rotating part of the machine tool. As mentioned above, a plurality of sensors and multiplexers may also be present in alternative embodiments of the monitoring system 12 shown in fig. 2-4, wherein the signal processing takes place in the processing unit 40. In these cases, the processing unit 40 controls the multiplexer.
Conventionally, the processing unit 40 uses the readings of the acoustic sensor 10 only during processing of the workpiece or during maintenance or dressing of the grinding wheel to detect ultrasonic emissions caused by contact between the grinding wheel and the workpiece or between the grinding wheel and a dressing tool (dresser). Thus, the readings of the vibration sensor 10 are conventionally (in a known manner) used only for checking the machining cycle or the maintenance cycle.
The processing unit 40 may also use the readings of the acoustic sensor 10 to detect any vibration peaks (i.e. peaks of acoustic emissions) during movement of the spindle 3 to and from the workpiece and/or during assembly and disassembly of the workpiece due to accidental collisions between the spindle 3 and the workpiece and/or between the spindle 3 and other components of the machine tool 1 (and due to errors in control). In other words, the acoustic sensor 10 (i.e. the monitoring system 12 comprises the acoustic sensor 10) is used by the processing unit 40 as a "whistle" about any undesired collision of the spindle 3 when the spindle 3 is displaced or the workpiece is close to the spindle 3. It is clear that when the signal provided by the acoustic sensor 10 indicates a (possible) collision, the processing unit 40 immediately sends it to the control unit of the machine tool, stopping the ongoing movement if necessary. This type of event may also be recorded by the processing unit 40 and/or the control unit of the machine tool, to allow reconstructing in the future all negative events that the spindle 3 has undergone.
In the above-described embodiment, the vibration sensor 10 is used, while according to other embodiments (not shown), a different type of sensor (e.g., a temperature sensor, a pressure sensor, an acceleration sensor, etc.) is used.
In the above-described embodiments, the movable part is the spindle 3 of the machine tool 1, while according to other embodiments (not shown) the movable part is a part having a different function in the machine tool 1 or other type of machine.
The embodiments described herein may be combined with each other without departing from the scope of the invention.
The monitoring system 12 described above provides several advantages.
First, the monitoring system 12 described above allows for an increase in signal-to-noise ratio by increasing the accuracy, sensitivity, and stability of the readings of the acoustic sensor 10. This result is obtained in particular by the presence of transmission lines adapted to provide differential signals. The transmission line defines a signal path. The signal paths are fully differential throughout the transmission line, i.e., the inputs and outputs of each component that forms part of the transmission line are differential, and the operations performed by each component are differential.
The transmission line starts from the acoustic sensor 10, comprises a first connection line 19, an amplifier 18 and a second connection line 20, and ends at the transceiver means 15 of the communication unit 14. Throughout its path, the signal is always fully differential and has high quality and strong immunity.
According to a preferred embodiment, the transmission lines of the differential signals pass from the acoustic sensor 10 through the communication unit 14 (also configured to keep the signal paths fully differential), the amplifier 22, the interface unit 13 and the corresponding electrical leads to the processing unit 40. In other words, according to a preferred embodiment, there is also a contactless communication unit 14, an amplifier 22 comprising two inputs connected to the second transmission means 16 and two outputs connected to the interface unit 13, the interface unit (13) itself and any electrical leads connecting the latter to the processing unit 40 forming part of a transmission line providing a differential signal.
In the embodiment shown in fig. 4-7, a single connection line 20 allows for the transmission of electrical power and signals of the vibration sensor 10 to the acoustic sensor 10. This allows to significantly reduce the number of electrical leads required for the system, with significant advantages in terms of miniaturization.
In the embodiment shown in fig. 7, the greater the number of inputs to the multiplexer, the greater the advantages described above.
In the embodiment shown in fig. 5-7, the analog signal generated by the acoustic sensor 10 is digitized in the rotor, so that the communication unit 14 transmits the digital signal in a contactless manner, which is not affected by noise or attenuation, unlike the analog signal.
In the embodiment shown in fig. 5-7, the signal generated by the acoustic sensor 10 has been processed in the movable part (or, according to an alternative embodiment not shown, in the stationary part) due to the presence of the processing means 38, the signal-to-noise ratio can be significantly improved.
Furthermore, performing the complete processing of the signals or most of such processing inside the rotor provides further significant advantages in addition to the aforementioned advantages.
First, the monitoring system, more specifically the rotor, is more powerful and has a higher autonomy, i.e. it autonomously performs more complex operations, significantly reducing the workload of the control device. The system may thus be improved by increasing, for example, the number and/or variety of monitoring processes, for example, adding more sensors and/or performing more types of inspection.
Furthermore, performing the complete processing of the signals or most of such processing inside the rotor allows the possibility of self-configuring the monitoring system based on the processed signals and the possibility of implementing self-diagnostic functions in the monitoring system, such as measuring temperature, voltage or other system parameters, and checking the reliability of the communication channel.
The processing of the signal generated by the acoustic sensor 10 can take place in a movable part (or, according to an alternative embodiment not shown, in a fixed part), even in a monitoring system that does not comprise a transmission line adapted to provide a differential signal.
Also, multiplexers may be used in a monitoring system that includes multiple sensors (and balance heads, if present) and does not include transmission lines adapted to provide differential signals.
Claims (15)
1. A monitoring system (12) for a movable part (3) connected to a fixed part (2), the monitoring system being connected to a processing unit (40) and comprising:
-an acoustic sensor (10) located in said movable part (3);
-a first amplifier (18) located in the movable part (3);
a contactless communication unit (14) having a first transceiver means (15) arranged in the movable part (3), and a second transceiver means (16) facing the first transceiver means (15) and arranged in the fixed part (2);
-a first connection line (19) connecting the acoustic sensor (10) to the first amplifier (18);
-a second connection line (20) connecting the first amplifier (18) to the first transceiver device (15);
the monitoring system (12) is characterized in that it comprises:
an analog-to-digital converter (37) placed in the movable part (3) or the fixed part (2) and configured to receive an analog signal and convert the analog signal into a digital signal; a kind of electronic device with high-pressure air-conditioning system
-processing means (38) placed in said movable part (3) or said fixed part (2) and configured to receive said digital signal from said analog-to-digital converter (37) to process said digital signal and to obtain and output a processed digital signal.
2. The monitoring system (12) according to claim 1, wherein the analog-to-digital converter (37) and the processing means (38) are placed in the movable part (3).
3. The monitoring system (12) of claim 1 or claim 2, wherein the digital signal is subjected to time and frequency domain processing.
4. A monitoring system (12) according to claim 3, wherein the signal processing is performed by using a fourier transform.
5. The monitoring system (12) of claim 4 wherein the signal processing is performed using a fast fourier transform.
6. The monitoring system (12) according to any of the preceding claims, comprising a second amplifier (33) placed in the movable part (3) and connected in series with the first amplifier (18) along the second connection line (20).
7. The monitoring system (12) according to any of the preceding claims, comprising a power supply circuit (23) provided with:
-a first power supply device (24) placed in the movable part (3) and providing power to the first amplifier (18);
an air-coupling transformer (26) including a first coil (27) placed in the movable member (3) and supplying power to the first power supply device (24), and a second coil (28) placed in the fixed member (2) and receiving power;
a second power supply device (25) placed in the fixed part (2), supplying power to the second coil (28), and supplying power to a third amplifier (22) placed in the fixed part (2) or to the second transceiver device (16);
-third power supply means (34) directly coupled to said first coil (27);
-coupling means (35) receiving power from the third amplifier (34) and feeding power into the second connection line (20), the power being in a frequency band different from the frequency band of the analog signal generated by the acoustic sensor (10); a kind of electronic device with high-pressure air-conditioning system
Decoupling means (36) which take power from the second connection line (20) and supply power to the first amplifier (24).
8. The monitoring system (12) of any one of the preceding claims, comprising a transmission line adapted to provide a differential signal, comprising:
the first amplifier (18) comprises two electrical input terminals and two electrical output terminals;
-the first connection line (19) comprises two electrical leads each connecting an electrical terminal (17) of the acoustic sensor (10) to a respective electrical input terminal of the first amplifier (18); a kind of electronic device with high-pressure air-conditioning system
The second connection line (20) comprises two electrical leads, each of which connects an electrical output terminal of the first amplifier (18) to the first transceiver device (15).
9. The monitoring system (12) according to claim 8, further comprising a third amplifier (22) placed in the stationary part (2) and comprising two electrical input terminals connected to the second transceiver means (16), and two electrical output terminals connectable to an interface unit (13) configured to distribute power and transmit signals out of or into the processing unit (40).
10. The monitoring system (12) according to claim 8 or claim 9, wherein the transmission line is adapted to provide a differential signal starting from the acoustic sensor (10) and ending at a processing unit (40) connected to the monitoring system (12).
11. The monitoring system (12) according to any one of the preceding claims, comprising:
two separate and independent acoustic sensors (10);
two first amplifiers (18);
two first connection lines (19), each of which connects the acoustic sensor (10) to the first amplifier (18) and comprises two electrical leads;
a single communication unit (14); a kind of electronic device with high-pressure air-conditioning system
A multiplexer (39) having two electrical input terminals connected to the two first amplifiers (18) and to a single electrical output terminal, connected to the first transceiver means (15) of the single communication unit (14).
12. The monitoring system (12) of any of the preceding claims, comprising a balancing head.
13. A method for obtaining a processed digital signal within a movable part (3) of a monitoring system (12) according to any of the preceding claims and transmitting said processed digital signal through a contactless communication unit (14) of said monitoring system (12), comprising the steps of:
increasing analog-to-digital acquisition dynamics by using SAR (successive approximation buffer) converters with improved resolution;
high frequency acquisition of the coarse fundamental frequency signal generated through the acoustic sensor 10, said frequency being higher than 2Mhz;
implementing a highly parametrizable stochastic process that remains highly efficient as the monitored process changes;
implementing an automatic parameter setting mode allowing automatic parameterization of the process based on observations of the monitored process; a kind of electronic device with high-pressure air-conditioning system
The processed digital signals are packetized so that real-time information with higher priority and lower priority information is transmitted over the same communication channel, the packetization of the processed digital signals being performed according to an optimized communication protocol that allows defining a hierarchical structure of information according to delays using the information.
14. The method according to claim 13, comprising the further step of: specific processing of multiple simultaneous measurements is performed based on the same coarse signal without the need to add dedicated hardware.
15. The method according to claim 13 or claim 14, wherein at least some of the steps of the method are carried out through the analog-to-digital converter (37) and the processing means (38) of the monitoring system (12).
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT102020000031346 | 2020-12-18 | ||
| IT102020000031355 | 2020-12-18 | ||
| IT102020000031349 | 2020-12-18 | ||
| IT102020000031355A IT202000031355A1 (en) | 2020-12-18 | 2020-12-18 | MONITORING SYSTEM FOR A MOBILE COMPONENT CONNECTED TO A FIXED COMPONENT |
| PCT/EP2021/086454 WO2022129502A2 (en) | 2020-12-18 | 2021-12-17 | Monitoring system for a movable component connected to a stationary component |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116723912A true CN116723912A (en) | 2023-09-08 |
Family
ID=75111661
Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180085348.3A Pending CN116669905A (en) | 2020-12-18 | 2021-12-17 | Monitoring system for movable assembly connected to fixed part |
| CN202180085350.0A Pending CN116723912A (en) | 2020-12-18 | 2021-12-17 | Monitoring system for movable assembly connected to fixed part |
| CN202180085349.8A Pending CN116635187A (en) | 2020-12-18 | 2021-12-17 | Monitoring system for movable assembly connected to fixed part |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180085348.3A Pending CN116669905A (en) | 2020-12-18 | 2021-12-17 | Monitoring system for movable assembly connected to fixed part |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202180085349.8A Pending CN116635187A (en) | 2020-12-18 | 2021-12-17 | Monitoring system for movable assembly connected to fixed part |
Country Status (2)
| Country | Link |
|---|---|
| CN (3) | CN116669905A (en) |
| IT (1) | IT202000031355A1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1263065B (en) | 1993-03-22 | 1996-07-24 | Marposs Spa | EQUIPMENT FOR DYNAMIC BALANCING OF A ROTATING BODY. |
| ITBO20020098A1 (en) * | 2002-02-28 | 2003-08-28 | Marposs Spa | ACOUSTIC SENSOR |
| ITBO20060489A1 (en) | 2006-06-23 | 2007-12-24 | Marposs Spa | CONTROL SYSTEM AND BALANCING DEVICE FOR TOOL MACHINE WITH ROTATING TOOL |
| ES2753535T3 (en) | 2014-04-23 | 2020-04-13 | Marposs Spa | Device and method for transmitting and receiving alternate optical signals |
-
2020
- 2020-12-18 IT IT102020000031355A patent/IT202000031355A1/en unknown
-
2021
- 2021-12-17 CN CN202180085348.3A patent/CN116669905A/en active Pending
- 2021-12-17 CN CN202180085350.0A patent/CN116723912A/en active Pending
- 2021-12-17 CN CN202180085349.8A patent/CN116635187A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN116635187A (en) | 2023-08-22 |
| CN116669905A (en) | 2023-08-29 |
| IT202000031355A1 (en) | 2022-06-18 |
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