Communication device

Abstract

This communication device (100) comprises: a sensor (S) that is attached to an object (52, T) to be detected and outputs an analog detection signal (SA1); and a modulated laser generation device (103) that generates a modulated laser (SL) by implementing a modulation process on a laser fundamental wave on the basis of the analog detection signal.

Description

communication equipment

[0001] The present disclosure relates to a communication device.

[0002] Patent Document 1 describes a method for determining whether a grinding wheel has become dull or chipped, in which an AE sensor is attached to a member for holding the grinding wheel, and the AE sensor detects elastic waves generated when a workpiece is ground by the grinding wheel, outputs an AE signal, and transmits the AE signal wirelessly as radio waves.

[0003] Patent Document 2 describes a communication system that transmits and receives information data using laser light as a digital signal. In this communication system, bright light is used as an on state and dark light is used as an off state, and information data is imparted to the laser light by converting the laser light into a digital signal by expressing the length of the on time and the length of the off time. As a method for generating bright light and dark light, the patent document describes turning a laser light source on and off, generating bright light when the laser light source is on and generating dark light when the laser light source is off. As another method for generating bright light and dark light, the patent document also describes generating bright light and dark light by continuously turning on the laser light source and changing the intensity of the laser light using an optical modulator.

[0004] International Publication No. 2021 / 153042 Japanese Patent Application Laid-Open No. 2022-36928

[0005] In recent years, there has been a demand for grasping, for example, the surface quality of a workpiece using information during processing. When the surface quality of a workpiece is detected using an AE sensor attached to a member for holding a grinding wheel as described in Patent Document 1, it has been found that components highly correlated with the surface quality of the workpiece contained in the analog signal output from the AE sensor include, for example, signals in a high frequency band of 1.0 MHz or more.

[0006] However, the strength of analog signals in the high-frequency band above 1.0 MHz is very weak. Furthermore, in wireless radio wave communication, the weak analog signals in the high-frequency band are subject to various noises, such as EMC noise generated by machine tools and other factory equipment, and switching noise generated by power supplies. As a result, it becomes difficult for a receiving device that receives an AE signal transmitted by radio wave to extract the desired analog signal, making it impossible to perform appropriate data analysis.

[0007] Patent Document 2 describes the use of visible light, i.e., laser light, instead of radio waves. Patent Document 2 also describes a technology for transmitting laser light as an on / off digital signal. When communicating using a laser to transmit analog signals such as AE signals, as described in Patent Document 2, it is necessary to A / D convert the analog signals such as AE signals to generate on / off digital signals. Then, the converted on / off digital signals are used to generate laser light that switches between bright light and dark light. Then, a receiving device needs to analyze the laser light as an on / off digital signal.

[0008] However, in order to enable a receiving device to analyze a high-frequency analog signal using a laser beam of a digital signal, a laser beam oscillator is required, which is expensive. As a result, even if the device described in Patent Document 2 is used, it is not easy to communicate a high-frequency analog signal using a laser beam.

[0009] The present disclosure has been made in consideration of such problems, and aims to provide a communication device that is less susceptible to noise and can communicate inexpensively, even if the analog detection signal of the communication target is a weak signal in the high-frequency band.

[0010] One aspect of the present disclosure is a communication device including: a sensor attached to an object to be detected and outputting an analog detection signal; and a modulated laser generator that generates a modulated laser by modulating a laser fundamental wave based on the analog detection signal.

[0011] According to one aspect of the present disclosure, a modulated laser generator constituting a communication device generates a modulated laser. Therefore, transmission using a modulated laser can be less susceptible to noise than transmission using radio waves. As a result, even if the analog detection signal of the communication target is a weak signal in the high-frequency band, it can be transmitted with less susceptibility to noise.

[0012] Furthermore, the modulated laser generated as the transmission signal is generated by modulating the laser fundamental wave based on the analog detection signal output by the sensor. In other words, the modulated laser is obtained by analog-modulating the laser fundamental wave. Therefore, the communication device can have a simple configuration and can be made inexpensive. Furthermore, since there is no need to A / D convert the analog detection signal, no A / D converter is required. Therefore, in this respect, the communication device can be made inexpensive.

[0013] As described above, according to the above aspect, it is possible to provide a communication device that is less susceptible to noise and can communicate inexpensively, even if the analog detection signal to be communicated is a weak signal in the high-frequency band.

[0014] It should be noted that the reference numerals in parentheses in the claims indicate the correspondence with the specific means described in the embodiments to be described later, and do not limit the technical scope of the present invention.

[0015] 1 is a plan view showing a grinding machine in embodiment 1. FIG. 2 is a diagram showing positions on a graph showing AE frequency and AE amplitude for each type of wear in grinding processing. FIG. 3 is an axial cross-sectional view of a communication device (wheel head and detection unit) portion of the grinding machine in embodiment 1. FIG. 4 is a diagram showing the function of each component of the communication device in embodiment 1. FIG. 5 is a diagram showing the relationship between the ratio of the AE signal SA1 and the demodulated AE signal SA2 at the modulation frequency of the modulated laser. FIG. 6 is a diagram showing the function of each component of the communication device in embodiment 2. FIG. 7 is a diagram showing the function of each component of the communication device in embodiment 3.

[0016] (First Embodiment) In the following, a case where the communication device 100 is applied to a grinding machine 1 will be described. However, the grinding machine 1 is merely one example of an application target of the communication device 100, and the communication device 100 can also be applied to various machine tools other than the grinding machine 1. Furthermore, the communication device 100 can be applied to various industrial machines and other devices that perform wireless communication in addition to machine tools.

[0017] 1. Configuration of Grinding Machine 1 The configuration of the grinding machine 1 will be described with reference to Fig. 1. The grinding machine 1 grinds the workpiece W by rotating the workpiece W, rotating the grinding wheel T, and moving the grinding wheel T relative to the workpiece W. For example, the grinding machine 1 plunge-grinds the workpiece W by moving the grinding wheel T relatively closer to the workpiece W in a direction intersecting the rotation axis of the workpiece W. The grinding machine 1 also traverse-grinds the workpiece W by moving the grinding wheel T relatively to the workpiece W in a direction parallel to the rotation axis of the workpiece W.

[0018] The grinding machine 1 can be a table traverse type grinding machine, a wheelhead traverse type grinding machine, or the like. The grinding machine 1 can also be a cylindrical grinding machine, a cam grinding machine, or the like. In this embodiment, the grinding machine 1 is exemplified by a table traverse type cylindrical grinding machine. That is, the grinding machine 1 is configured to move the workpiece W in the axial direction of the workpiece W and move the grinding wheel T in a direction intersecting the axial line of the workpiece W. In the following description, the X-axis direction indicates a direction perpendicular to the axial line of the workpiece W, and the Z-axis direction indicates a direction parallel to the axial line of the workpiece W.

[0019] The grinding machine 1 includes a bed 10, a table 20, a spindle device 30, a tailstock device 40, a wheel head 50, a detection unit 60, a sizing device 70, and a control device 80. In this embodiment, the wheel head 50, the detection unit 60, and a surface texture estimation unit (described later) of the control device 80 constitute a communication device 100.

[0020] The bed 10 is placed on a placement surface. The bed 10 is formed, for example, in an inverted T shape. That is, the width (length in the Z-axis direction) of the front side in the X-axis direction (lower side in FIG. 1 ) of the bed 10 is long, and the width of the back side in the X-axis direction (upper side in FIG. 1 ) is short.

[0021] The bed 10 is provided with a Z-axis guide surface 11 extending in the Z-axis direction on the upper surface on the front side in the X-axis direction. The bed 10 further includes a Z-axis drive mechanism 12 that drives along the Z-axis guide surface 11. In this embodiment, the Z-axis drive mechanism 12 includes a ball screw mechanism 12a and a Z-axis motor 12b. Note that a linear motor can also be applied to the Z-axis drive mechanism 12 instead of the configuration including the ball screw mechanism 12a.

[0022] Furthermore, the bed 10 is provided with a guide surface 13 on the upper surface on the rear side in the X-axis direction, which extends in a direction intersecting the Z-axis direction. In this embodiment, the guide surface 13 is an X-axis guide surface that extends in the X-axis direction, which is perpendicular to the Z-axis. The bed 10 is further provided with an X-axis drive mechanism 14 that drives along the X-axis guide surface 13. In this embodiment, the X-axis drive mechanism 14 is provided with a ball screw mechanism 14a and an X-axis motor 14b, as an example. Note that a linear motor can also be applied to the X-axis drive mechanism 14 instead of the configuration that includes the ball screw mechanism 14a.

[0023] The table 20 is formed in an elongated shape and is supported movably in the Z-axis direction (horizontal left-right direction) on the Z-axis guide surface 11 of the bed 10. The table 20 is also fixed to a ball screw nut of the Z-axis ball screw mechanism 12a, and moves in the Z-axis direction by the rotational drive of the Z-axis motor 12b.

[0024] The spindle device 30 supports the workpiece W and drives it to rotate. The spindle device 30 is disposed on one end side in the Z-axis direction on the table 20. The spindle device 30 includes a spindle housing 31, a spindle 32, a spindle motor 33, a center member 34, and a drive force transmission mechanism 35.

[0025] The spindle housing 31 is fixed onto the table 20. The spindle 32 is rotatably supported by the spindle housing 31 via a bearing. A spindle motor 33 rotationally drives the spindle 32. The center member 34 supports an end face of one axial end of the workpiece W. The center member 34 may be fixed to the spindle housing 31 so as to be non-rotatable, or may be fixed to the spindle 32 so as to be rotatable relative to the spindle housing 31.

[0026] The driving force transmission mechanism 35 is provided on the axial end face of the main shaft 32 and transmits the rotational driving force of the main shaft 32 to the workpiece W, thereby rotating the workpiece W. The driving force transmission mechanism 35 is, for example, a turning member provided at a position eccentric from the axis of the main shaft 32. In other words, the turning member serving as the driving force transmission mechanism 35 is an eccentric drive pin that extends from the axial end face of the main shaft 32 in the axial direction of the main shaft 32. The turning member revolves around the axis of the main shaft 32 as the main shaft 32 rotates. In this embodiment, the turning member serving as the driving force transmission mechanism 35 engages with a carrier Wa attached to the workpiece W in one direction of rotation, thereby rotating the workpiece W about the axis of the main shaft 32.

[0027] The tailstock device 40 is disposed on the other end side in the Z-axis direction on the table 20. The tailstock device 40 includes a center member 41. The center member 41 supports the end face of the other axial end of the workpiece W. The center member 41 may be provided so as to be non-rotatable or so as to be rotatable.

[0028] The wheel head 50 includes a grinding wheel T and rotates the grinding wheel T. In addition to the grinding wheel T, the wheel head 50 includes a wheel head body 51, a grinding spindle unit 52, a grinding wheel motor 53, and a grinding wheel cover 54.

[0029] The grinding wheel T is formed in a disk shape. The grinding wheel T is used to grind the outer peripheral surface of a workpiece W. The grinding wheel T is composed of a plurality of abrasive grains fixed with a binder. The abrasive grains used may be general abrasive grains made of ceramic materials such as alumina or silicon carbide, or super abrasive grains such as diamond or CBN.

[0030] The wheel head body 51 is formed, for example, in a rectangular shape, and is supported on the X-axis guide surface 13 of the bed 10 so as to be movable in the X-axis direction (horizontal front-to-back direction). The wheel head body 51 is also fixed to the ball screw nut of the X-axis ball screw mechanism 14a, and is moved in the X-axis direction by the rotational drive of the X-axis motor 14b. Furthermore, the wheel head body 51 has a cylindrical portion serving as an axis housing at the front in the X-axis direction.

[0031] The grinding spindle unit 52 is rotatably supported via a bearing (not shown) on the cylindrical portion of the grinding head main body 51. The grinding spindle unit 52 holds the grinding wheel T, and the grinding wheel T rotates as the grinding spindle unit 52 rotates. The grinding wheel motor 53 rotationally drives the grinding spindle unit 52. For example, the grinding wheel motor 53 transmits a rotational drive force to the grinding spindle unit 52 via a belt. However, the grinding wheel motor 53 may be disposed coaxially with the grinding spindle unit 52.

[0032] The grinding wheel cover 54 is non-rotatably attached to the wheel head body 51 and covers a portion of the grinding wheel T. The grinding wheel cover 54 is open at least in the area facing the workpiece W (the front side in the X-axis direction), exposing the grinding wheel T.

[0033] The detection unit 60 is attached to the grinding wheel T or the grinding spindle unit 52 as the detection object, and includes a sensor S that outputs an analog detection signal. In this embodiment, the sensor S is an AE sensor that detects elastic waves generated in the grinding wheel T when the workpiece W is ground by the grinding wheel T, and outputs an AE signal as an analog detection signal. Hereinafter, the sensor S will be referred to as the AE sensor S. The detection unit 60 can wirelessly communicate the analog detection signal output by the AE sensor S.

[0034] The sizing device 70 is provided on the upper surface of the bed 10 and measures the outer diameter dimension of the workpiece W. The sizing device 70 is equipped with, for example, a pair of contacts that can come into contact with the outer peripheral surface of the workpiece W, and measures the outer diameter dimension at the contact point with the workpiece W.

[0035] The control device 80 is a CNC device that executes machining control. That is, the control device 80 drives the Z-axis drive mechanism 12 and the X-axis drive mechanism 14, which serve as moving devices, based on the machining program and the measurement results from the sizing device 70, to control the positions of the table 20 and the wheel head 50. That is, the control device 80 controls the positions of the table 20, the wheel head 50, etc., thereby moving the workpiece W and the grinding wheel T closer to or farther apart from each other. Furthermore, the control device 80 controls the spindle device 30 and the wheel head 50. That is, the control device 80 controls the rotation of the spindle 32 and the grinding wheel T.

[0036] The control device 80 can also estimate the surface texture of the workpiece W based on the AE signal detected by the AE sensor S constituting the detection unit 60, and perform processing control based on the estimated surface texture of the workpiece W. For example, the control device 80 can determine whether the workpiece W is a good product by estimating the processing quality of the workpiece W based on the estimated surface texture of the workpiece W, or estimate the surface condition of the grinding wheel T. The estimation result of the surface condition of the grinding wheel T can also be used to determine the timing to adjust the grinding wheel T or to determine the timing to replace the grinding wheel T.

[0037] 2. Wear in Grinding Wear in grinding will be explained with reference to Fig. 2. Grinding by a grinding machine 1 is a phenomenon in which a relatively soft workpiece W is finely ground away by hard abrasive grains that make up the grinding wheel T. It has been discovered that grinding is a combined phenomenon of abrasive wear and severe wear.

[0038] The AE sensor S of the grinding machine 1 detects elastic waves caused by wear during grinding and outputs an AE signal as an analog detection signal. Each type of wear is expressed as the relationship between the frequency of the AE signal and the amplitude of the AE signal.

[0039] 2, the frequency of the AE signal is 0.1 MHz to 0.3 MHz for mild wear, 0.3 MHz to 1.1 MHz for abrasive wear, and 0.9 MHz to 1.6 MHz for severe wear. The amplitude of the AE signal is relatively small for mild wear and abrasive wear, and large for severe wear.

[0040] 3. Configuration of Communication Device 100 The configuration of the communication device 100 will be described with reference to Fig. 3. The communication device 100 is configured to include a grinding wheel head 50, a detection unit 60, and part of the control device 80 (such as a surface texture estimation unit 81 described below). Fig. 3 shows part of the grinding wheel head 50 and the detection unit 60. The communication device 100 is equipped with an AE sensor S, and wirelessly communicates an AE signal output by the AE sensor S. The communication device 100 estimates the surface texture of the workpiece W, for example, based on the AE signal.

[0041] As described above, the grinding wheel head 50 includes the grinding wheel T, the grinding wheel head main body 51, the grinding wheel spindle unit 52, the grinding wheel motor 53, and the grinding wheel cover 54. The grinding wheel spindle unit 52 includes the grinding wheel spindle 52a and the mounting member 52b. The grinding wheel spindle 52a is axially shaped and is rotatably supported via a bearing in the cylindrical portion of the grinding wheel head main body 51. The grinding wheel T is fitted onto the tip of the grinding wheel spindle 52a. The mounting member 52b is a member that holds the grinding wheel T by clamping it in the axial direction at the tip of the grinding wheel spindle 52a. Therefore, the grinding wheel T, the grinding wheel spindle 52a, and the mounting member 52b rotate together.

[0042] The detection unit 60 includes a first unit 61 and a second unit 62. The first unit 61 is attached to the grinding spindle unit 52 or the grinding wheel T, which is the object to be detected. The grinding spindle unit 52 and the grinding wheel T are rotating bodies that rotate integrally around the rotation center line Ct. Therefore, the first unit 61 rotates together with the grinding spindle unit 52 and the grinding wheel T around the rotation center line Ct. The second unit 62 is attached to the grinding wheel cover 54 or a member that is integral with the grinding wheel cover 54. The second unit 62 is attached to, for example, the grinding wheel head body 51 or the grinding wheel cover 54. In other words, the first unit 61 rotates relative to the second unit 62 around the rotation center line Ct.

[0043] The first unit 61 includes a first unit housing 101 , an AE sensor S, a power supply unit 102 , a modulated laser generator 103 , a mounting screw 104 , and a power receiving coil 105 .

[0044] The first unit housing 101 is formed in a cylindrical shape with a bottom. The outer bottom surface of the first unit housing 101 is attached to the axial end surface of the grinding wheel spindle unit 52 so that the first unit housing 101 and the grinding wheel spindle unit 52 are coaxial. More specifically, the first unit housing 101 is attached to the axial end surface of the mounting member 52b, that is, the opening side of the first unit housing 101 is located on the opposite side to the grinding wheel spindle unit 52.

[0045] The cylindrical interior of the first unit housing 101 accommodates the AE sensor S, power supply unit 102, modulated laser generator 103, and mounting screws 104. As described above, the AE sensor S detects elastic waves generated in the grinding wheel T when the workpiece W is ground by the grinding wheel T, and outputs an AE signal as an analog detection signal. The AE sensor S detects elastic waves caused by mild wear, abrasive wear, and severe wear, and outputs an AE signal SA1 as an analog detection signal. The AE sensor S is attached to a central recess located on the rotation center line Ct in the bottom surface of the first unit housing 101.

[0046] The power supply unit 102 includes a storage battery and a power receiving circuit, and is provided on the bottom side of the first unit housing 101. The power supply unit 102 supplies driving power to the AE sensor S and the modulated laser generator 103.

[0047] The modulated laser generator 103 is disposed closer to the opening of the first unit housing 101 than the power supply unit 102, and is stacked on the power supply unit 102. The modulated laser generator 103 generates a modulated laser beam SL by modulating a laser fundamental wave based on the AE signal SA1 output by the AE sensor S. The modulated laser generator 103 generates the modulated laser beam SL along the rotation center line Ct toward the opening of the first unit housing 101.

[0048] The modulated laser SL may be a laser in which a laser fundamental wave has been subjected to amplitude modulation processing, or may be a laser in which a laser fundamental wave has been subjected to frequency modulation processing.

[0049] The modulated laser generator 103 is configured to generate, for example, a semiconductor laser. The modulated laser generator 103 may be configured to generate, for example, a vertical-cavity surface-emitting laser, or may be configured to generate an edge-emitting laser. The modulated laser generator 103 may have, for example, a laser bandwidth of 4 GHz and an emission wavelength of approximately 850 nm. By adopting this configuration, the modulated laser generator 103 can generate a modulated laser containing components of abrasive wear and severe wear. However, the modulated laser generator 103 is not limited to this configuration. For example, an emission wavelength of 400 nm to 800 nm may also be applied.

[0050] The mounting screw 104 is threaded into the inner peripheral surface of the first unit housing 101 and holds the power supply unit 102 and the modulated laser generator 103 in a sandwiched state in the axial direction. A through hole is formed in the center of the mounting screw 104 along the rotation center line Ct. This through hole is formed to a size that allows the modulated laser SL to pass through.

[0051] The receiving coil 105 is disposed at the open end of the first unit housing 101. The receiving coil 105 is a coil for contactless power supply and is connected to the power receiving circuit of the power supply unit 102. The power acquired via the receiving coil 105 is stored in a storage battery of the power supply unit 102. Furthermore, a through hole is formed in the center of the receiving coil 105 along the rotation center line Ct. This through hole is formed to a size that allows the modulated laser SL to pass through.

[0052] Here, the power supply unit 102 and the power receiving coil 105 are provided integrally with the modulated laser generator 103 and constitute a contactless power receiving unit configured to supply power to the AE sensor S and the modulated laser generator 103. The contactless power receiving unit is not limited to a configuration having the power receiving coil 105, and other configurations can be adopted as long as power can be received contactlessly.

[0053] The second unit 62 includes a unit cover 111 , a second unit housing 112 , a power supply unit 113 , a laser receiving device 114 , and a power supply coil 115 .

[0054] The unit cover 111 is attached to the wheel head body 51 or the grinding wheel cover 54. Therefore, the unit cover 111 is provided so as not to rotate. In this embodiment, the unit cover 111 is attached to the grinding wheel cover 54. The unit cover 111 houses other elements 112, 113, 114, and 115 that make up the second unit 62.

[0055] The second unit housing 112 is attached to the unit cover 111, and is disposed opposite the first unit 61 in the direction of the rotation center line Ct. The second unit housing 112 is formed in a cylindrical shape with a bottom, and is disposed so that the opening side faces the first unit 61.

[0056] The power supply unit 113 includes a power supply circuit and is provided on the bottom side of the cylindrical interior of the second unit housing 112 .

[0057] The laser receiving device 114 is housed inside the cylindrical second unit housing 112. Therefore, the laser receiving device 114 is non-rotatable and is disposed opposite the modulated laser generator 103 in the direction of the rotation center line Ct. The laser receiving device 114 receives the modulated laser beam SL generated by the modulated laser generator 103. In particular, the laser receiving device 114 receives the modulated laser beam generated along the rotation center line Ct. The laser receiving device 114 then performs a demodulation process on the received modulated laser beam SL to generate a demodulated analog signal SA2. Hereinafter, the demodulated analog signal SA2 will be referred to as a demodulated AE signal.

[0058] The laser receiving device 114 may be, for example, a Si high-speed photodiode. The response of the laser receiving device 114 may be, for example, 2 GHz. By adopting this configuration, the laser receiving device 114 can generate a demodulated AE signal SA2 that includes components of abrasive wear and severe wear. However, the laser receiving device 114 is not limited to this configuration.

[0059] The modulated laser beam SL is generated from the modulated laser generator 103 of the rotating first unit 61 and is received by the laser receiver 114 of the non-rotatable second unit 62. Here, since the modulated laser beam SL is generated along the rotation center line Ct, the position of the modulated laser beam SL does not deviate significantly. Therefore, the laser receiver 114 can reliably receive the modulated laser beam generated from the rotating modulated laser generator 103.

[0060] The power feeding coil 115 is disposed at the open end of the second unit housing 112. The power feeding coil 115 is a coil for contactless power feeding and is connected to a power feeding circuit of the power feeding unit 113. The power feeding coil 115 faces the power receiving coil 105 at a distance. Furthermore, a through hole is formed in the center of the power feeding coil 115 along the rotation center line Ct. This through hole is sized to allow the modulated laser SL to pass through.

[0061] Here, the power supply unit 113 and the power supply coil 115 are provided integrally with the laser receiving device 114, and constitute a contactless power supply unit configured to be able to supply power contactlessly to the power supply unit 102 and the power receiving coil 105 as a contactless power receiving unit that constitutes the first unit 61. The contactless power receiving unit is not limited to a configuration including the power supply coil 115, and other configurations may be adopted as long as they are capable of contactless power supply.

[0062] 4. Functional Configuration of Communication Device 100 The functional configuration of the communication device 100 will be described with reference to Fig. 4. As shown in Fig. 4, the AE sensor S outputs an AE signal SA1, which is an analog detection signal. The AE signal SA1 is a signal based on elastic waves caused by mild wear, abrasive wear, and severe wear.

[0063] The AE signal SA1 is converted into a modulated laser beam SL in the modulated laser generator 103. In Fig. 4, the modulated laser beam SL is a laser beam in which a laser fundamental wave is subjected to amplitude modulation based on the AE signal SA1. In other words, the frequency of the modulated laser beam SL is the same as that of the laser fundamental wave, and the amplitude of the modulated laser beam SL corresponds to the AE signal SA1.

[0064] In particular, the modulation frequency band of the modulated laser SL includes a frequency band of at least 1.0 MHz or higher. More preferably, the modulation frequency band of the modulated laser SL includes at least any frequency band in the range of 1.0 MHz to 2.0 MHz. Therefore, the modulated laser SL can reliably transmit components of abrasive wear and severe wear. In this embodiment, the modulation frequency band of the modulated laser SL includes both a frequency band of 1.0 MHz or higher and any frequency band in the range of 50 kHz to 500 kHz. Therefore, the modulated laser SL can more reliably transmit components of abrasive wear and severe wear. For example, the modulation frequency band of the modulated laser SL is 300 kHz to 1.8 MHz.

[0065] The modulated laser beam SL is generated from the modulated laser generator 103 of the rotating first unit 61 and received by the laser receiver 114 of the non-rotatable second unit 62. By using the modulated laser beam SL, wireless communication is possible between the modulated laser generator 103 and the laser receiver 114. Furthermore, as described with reference to FIG. 3 , the modulated laser beam SL is generated along the rotation center line Ct. Therefore, even though the modulated laser generator 103 and the laser receiver 114 rotate relative to each other, the position of the generated modulated laser beam SL does not deviate significantly, and the laser receiver 114 can reliably receive the modulated laser beam.

[0066] The control device 80 includes a surface quality estimation unit 81. The surface quality estimation unit 81 acquires the demodulated AE signal SA2 and estimates the surface quality of the workpiece W based on the demodulated AE signal SA2. The AE signal SA1 contains components of mild wear, abrasive wear, and severe wear, and the modulated laser SL is a laser containing components of abrasive wear and severe wear. The demodulated AE signal SA2 is a signal that retains the components of abrasive wear and severe wear. Therefore, by analyzing the demodulated AE signal SA2, it is possible to grasp the combined phenomenon of abrasive wear and severe wear, and to estimate the surface quality of the workpiece W.

[0067] The control device 80 can use the estimation results of the surface property estimation unit 81 to determine whether the workpiece W is good or bad. Although the example in which the control device 80 includes the surface property estimation unit 81 has been given, the surface property estimation unit 81 may be included in a processing device different from the control device 80.

[0068] 5. Relationship Between AE Signal SA1 and Demodulated AE Signal SA2 The relationship between the AE signal SA1 and the demodulated AE signal SA2 will be described with reference to Fig. 5. As described above, the AE signal SA1 is converted by the modulated laser SL, and the demodulated AE signal SA2 is generated using the modulated laser SL. In other words, the AE signal SA1 and the demodulated AE signal SA2 are signals converted via the modulated laser SL.

[0069] The ratio (SA1 / SA2) of the AE signal SA1 to the demodulated AE signal SA2 varies depending on the modulation frequency of the modulation laser. This relationship is shown in Figure 5. Here, the modulation frequency corresponds to the frequency of the AE signal SA1.

[0070] 5, the vertical axis (unit: dB) indicates the common logarithm of the ratio between the AE signal SA1 and the demodulated AE signal SA2. That is, 0 on the vertical axis corresponds to a ratio of 1 between the AE signal SA1 and the demodulated AE signal SA2. Therefore, in FIG. 5, when the modulation frequency is in the range of 100 kHz to 1.0 MHz, the ratio between the AE signal SA1 and the demodulated AE signal SA2 is 1. However, depending on the configuration of the communication device 100, even if there is a range in which the ratio between the AE signal SA1 and the demodulated AE signal SA2 is approximately constant, the ratio may be a value other than 1.

[0071] As shown in FIG. 5, when the modulation frequency is in the range Δf of 50 kHz to 2.0 MHz, the ratio between the AE signal SA1 and the demodulated AE signal SA2 falls within a predetermined tolerance range. The tolerance range here refers to a predetermined range that takes into account variations. In other words, the modulation frequency in the range Δf of 50 kHz to 2.0 MHz is a frequency band in which the ratio between the AE signal SA1 before modulation processing and the demodulated AE signal SA2 is a nearly constant value (almost 1, 0 dB in FIG. 5). In other words, the modulation frequency in the range Δf of 50 kHz to 2.0 MHz has sufficient linearity. Furthermore, as shown in FIG. 5, when the modulation frequency is in the range of 80 kHz to 1.5 MHz, the ratio between the AE signal SA1 before modulation processing and the demodulated AE signal SA2 falls within a minimal range, demonstrating extremely high linearity.

[0072] If the ratio between the AE signal SA1 and the demodulated AE signal SA2 is approximately 1 (0 dB), the AE signal SA1 and the demodulated AE signal SA2 will approximately match in the modulation frequency range Δf of 50 kHz to 2.0 MHz. However, even if the ratio is not 1, as long as the modulation frequency range Δf is within a predetermined tolerance range, the AE signal SA1 and the demodulated AE signal SA2 have a certain relationship, and therefore the AE signal SA1 can be estimated from the demodulated AE signal SA2.

[0073] 2, the modulation frequency band Δf of 50 kHz to 2.0 MHz, in which the ratio of the AE signal SA1 before modulation to the demodulated AE signal SA2 is approximately constant, includes the frequency bands of abrasive wear and severe wear. Therefore, it can be seen that the components of abrasive wear and severe wear can be transmitted using the modulated laser SL.

[0074] 6. Effect of the Embodiment According to the communication device 100 of this embodiment, the modulated laser generator 103 constituting the communication device 100 generates a modulated laser SL. Therefore, transmission using the modulated laser SL can be less susceptible to noise than transmission using radio waves. As a result, even if the analog detection signal (AE signal) SA1 of the communication target is a weak signal in the high-frequency band, it can be transmitted with less susceptibility to noise.

[0075] Furthermore, the modulated laser SL generated as the transmission signal is generated by modulating the laser fundamental wave based on the AE signal SA1 output by the AE sensor S. In other words, the modulated laser SL is obtained by performing analog modulation on the laser fundamental wave. Therefore, the communication device 100 can adopt a simple configuration and can be made inexpensively. Furthermore, since the AE signal SA1, which is an analog detection signal, does not need to be A / D converted, no A / D converter is required. Therefore, in this respect as well, the communication device 100 can be made inexpensively.

[0076] Therefore, according to the communication device 100 of this embodiment, even if the AE signal SA1, which is an analog detection signal of the communication target, is a weak signal in the high frequency band, it is less susceptible to the influence of noise and can communicate inexpensively.

[0077] Furthermore, the laser receiving device 114 constituting the communication device 100 receives the modulated laser SL generated by the modulated laser generating device 103 and performs demodulation processing on the modulated laser SL to generate a demodulated analog signal (demodulated AE signal) SA2, thereby enabling the communication device 100 to transmit and receive the AE signal SA1 via the modulated laser SL.

[0078] The modulated laser generator 103 performs amplitude modulation as modulation processing. By applying amplitude modulation processing, modulation processing based on the AE signal SA1 can be easily and reliably performed on the laser fundamental wave.

[0079] The AE sensor S is attached to the grinding wheel T or the grinding spindle unit 52, which is a rotating body to be detected. The modulated laser generator 103 is disposed at the axial end of the grinding wheel T or the grinding spindle unit 52, and generates a modulated laser beam SL along the rotation center line Ct. Even if the modulated laser generator 103 is attached to a rotating body, generating the modulated laser beam SL along the rotation center line Ct prevents positional deviation of the modulated laser beam SL. Therefore, the modulated laser beam SL can be transmitted from a stable position.

[0080] The laser receiving device 114 is non-rotatable, disposed opposite the modulated laser generator 103 in the direction of the rotation center line Ct, and receives the modulated laser SL generated along the rotation center line Ct. In other words, even when the modulated laser generator 103 and the laser receiving device 114 rotate relative to each other, the laser receiving device 114 can reliably receive the modulated laser SL.

[0081] The AE sensor S is attached to the grinding wheel T or the grinding spindle unit 52, detects elastic waves generated in the grinding wheel T, and outputs an AE signal as an analog detection signal. As a result, the phenomenon of the grinding process can be reliably analyzed.

[0082] The AE sensor S is attached to the grinding wheel T or the grinding spindle unit 52, detects elastic waves generated in the grinding wheel T, and outputs an AE signal, and the laser receiver 114 is attached to the grinding wheel cover 54. By adopting such an attachment relationship, the AE sensor S, modulated laser generator 103, and laser receiver 114 can be attached in desired positions.

[0083] In this embodiment, the AE sensor S detects elastic waves caused by abrasive wear or severe wear during grinding and outputs an AE signal SA1. In addition, the laser receiver 114 generates a demodulated AE signal SA2 containing a component of abrasive wear or severe wear. This makes it possible to reliably grasp the phenomenon of grinding.

[0084] Furthermore, the modulation frequency band of the modulated laser SL preferably includes a frequency band of at least 1.0 MHz or higher. More preferably, the modulation frequency band of the modulated laser SL preferably includes at least any frequency band in the range of 1.0 MHz to 2.0 MHz. Even in such a high-frequency band, the AE signal SA1 can be reliably communicated because it is less susceptible to noise. Furthermore, the modulation frequency band of the modulated laser SL preferably includes both a frequency band of 1.0 MHz or higher and any frequency band in the range of 50 kHz to 500 kHz. By including a low-frequency band in addition to a high-frequency band in this way, the phenomenon of the grinding process can be reliably grasped.

[0085] In particular, the modulation frequency band of the modulated laser SL should be a frequency band in which the ratio (SA1 / SA2) of the AE signal SA1 before modulation to the demodulated AE signal SA2 after demodulation is approximately constant, so that the state of the AE signal SA1 can be grasped with high accuracy using the demodulated AE signal SA2.

[0086] Furthermore, the surface quality estimation unit 81 estimates the surface quality of the workpiece W ground by the grinding wheel T based on the demodulated AE signal SA2. Because abrasive wear and severe wear can be determined based on the demodulated AE signal SA2, the surface quality of the workpiece W estimated using the demodulated AE signal SA2 can be highly accurate.

[0087] The detection unit 60 also includes a rotatable first unit 61 and a non-rotatable second unit 62. The first unit 61 is provided with an AE sensor S and a modulated laser generator 103, and further includes a non-contact power receiving unit (102, 105) that is integrally provided with the modulated laser generator 103 and configured to supply power to the AE sensor S. On the other hand, the second unit 62 is provided with a laser receiving device 114 and further includes a non-contact power feeding unit (113, 115) that is integrally provided with the laser receiving device 114 and configured to be able to feed power contactlessly to the non-contact power receiving unit (102, 105). Therefore, even if the AE sensor S and the modulated laser generator 103 are provided on the rotating first unit 61, power can be supplied to them.

[0088] (Embodiment 2) A communication device 200 of this embodiment will be described with primary reference to Fig. 6 and secondary reference to Fig. 5. The communication device 200 of this embodiment differs from the communication device 100 of embodiment 1 in the configuration of a laser receiving device 214. The laser receiving device 214 will be described below. Note that, of the symbols used in embodiment 2 and onwards, those that are the same as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified.

[0089] The laser receiving device 214 receives the modulated laser SL generated by the modulated laser generator 103 and generates a demodulated AE signal SA2. In this embodiment, as shown in FIG. 5, the ratio between the AE signal SA1 and the demodulated AE signal SA2 is a substantially constant value of 1 (0 dB) when the modulation frequency is between 50 kHz and 2.0 MHz. If the ratio is not 1 (0 dB), the AE signal SA1 and the demodulated AE signal SA2 will not match, although they will have a certain relationship.

[0090] Therefore, in this embodiment, even if the ratio in FIG. 5 is not 1, the laser receiving device 214 corrects the demodulated AE signal SA2 so that the demodulated AE signal SA2 matches the AE signal SA1.

[0091] In this case, as shown in FIG. 6 , the laser receiving device 214 includes a receiving unit 201, a demodulation processing unit 202, and a correction unit 203. The receiving unit 201 receives a modulated laser beam SL. The demodulation processing unit 202 performs demodulation processing on the received modulated laser beam SL to generate a pre-correction demodulated AE signal. The correction unit 203 corrects the demodulated pre-correction demodulated AE signal to generate a post-correction demodulated AE signal SA2. Even if the pre-correction demodulated AE signal does not match the AE signal SA1, the post-correction demodulated AE signal SA2 can be made to match the AE signal SA1.

[0092] According to this embodiment, since the corrected demodulated AE signal SA2 coincides with the AE signal SA1, highly accurate processing can be performed in processing using the corrected demodulated AE signal SA2. For example, when the surface texture estimation unit 81 estimates the surface texture of the workpiece W, the surface texture of the workpiece W can be estimated with high accuracy.

[0093] (Embodiment 3) A communication device 300 of this embodiment will be described with reference to Fig. 7. The communication device 300 of this embodiment differs from the communication device 100 of embodiment 1 in the configurations of a modulated laser generator 301 and a laser receiver 302. The modulated laser generator 301 and the laser receiver 302 will be described below.

[0094] The modulated laser generator 301 generates a modulated laser beam SL by frequency-modulating a laser fundamental wave based on the AE signal SA1. That is, the modulated laser beam SL has a constant amplitude but a different frequency from the laser fundamental wave. The laser receiver 302 receives the modulated laser beam SL and performs a demodulation process to generate a demodulated AE signal SA2. In this embodiment, the demodulation process in the laser receiver 302 is a frequency demodulation process.

[0095] This embodiment also provides the same effects as those of the first embodiment. However, amplitude modulation is easier than frequency modulation in generating modulated laser light. Therefore, the amplitude modulation of the first embodiment can generate modulated laser light more easily.

[0096] (Other) In the above embodiment, the communication devices 100, 200, and 300 have been described as being applied to the grinding machine 1. However, the communication devices 100, 200, and 300 can also be applied to devices other than the grinding machine 1. For example, the communication devices can be applied to machine tools other than the grinding machine 1, and can also be applied to other industrial machines.

[0097] In the above embodiment, the AE sensor S has been described as an example of a sensor that outputs an analog detection signal. However, the present invention is applicable to sensors other than the AE sensor S as long as they output an analog detection signal. This is particularly useful when wirelessly communicating analog detection signals in a high frequency band of 1.0 MHz or higher.

Claims

1. A grinding wheel (T) for grinding a workpiece (W); a grinding wheel spindle unit (52) for holding the grinding wheel; a grinding wheel cover (54) that is non-rotatable and covers a part of the grinding wheel; A first unit (61) attached to an axial end surface of the grinding spindle unit; a laser receiver (114, 214, 302) attached to the grinding wheel cover or to a member integral with the grinding wheel cover; The first unit is a first unit housing (101) formed in a bottomed cylindrical shape, the bottom outer surface of which is attached to the axial end surface of the grinding wheel spindle unit so as to be coaxial with the grinding wheel spindle unit; an AE sensor (S) disposed inside the cylindrical first unit housing, which detects elastic waves generated in the grinding wheel and outputs an AE signal as an analog detection signal (SA1); A power supply unit (102) disposed within the cylindrical interior of the first unit housing; a modulated laser generator (103, 301) disposed inside the cylindrical first unit housing and configured to generate a modulated laser (SL) by modulating a laser fundamental wave based on the analog detection signal; The laser receiving device receives the modulated laser generated by the modulated laser generating device, and generates a demodulated analog signal (SA2) by performing a demodulation process on the modulated laser.

2. The grinding wheel spindle unit holds the grinding wheel at its axial end, The communication device according to claim 1 , wherein the first unit is attached to an end surface of a tip end of the grinding wheel spindle unit in an axial direction.

3. The modulated laser generator generates the modulated laser along a rotation center line (Ct) of the grinding spindle unit, 3. The communication device according to claim 2, wherein the laser receiving device is disposed opposite to the first unit in a direction of a rotational center line of the grinding spindle unit and receives the modulated laser generated along the rotational center line of the grinding spindle unit.

4. Further, a second unit (62) is attached to the grinding wheel cover, The second unit is The laser receiving device; The communication device according to any one of claims 1 to 3, further comprising: a unit cover (111) that houses the laser receiving device and is attached to the grinding wheel cover.

5. The grinding wheel spindle unit is A grindstone spindle (52a); and a mounting member (52b) that holds the grinding wheel by clamping it in the axial direction at the tip of the grinding wheel spindle. The communication device according to any one of claims 1 to 3, wherein the first unit is attached to an axial end surface of the attachment member of the grinding wheel spindle unit.

6. 4. The communication device according to claim 1, wherein the modulated laser generator performs amplitude modulation as the modulation process.

7. The AE sensor detects the elastic wave caused by abrasive wear or severe wear in a grinding process and outputs the AE signal as the analog detection signal; The communication device according to claim 1 , wherein the laser receiving device generates the demodulated analog signal including a component of the abrasive wear or the severe wear.

8. 4. The communication device according to claim 1, wherein the modulation frequency band of the modulated laser includes at least a frequency band of 1.0 MHz or more.

9. 9. The communication device according to claim 8, wherein the modulation frequency band in the modulated laser includes a frequency band of 1.0 MHz or more and any frequency band in a range of 50 kHz to 500 kHz.

10. A communication device according to any one of claims 1 to 3, wherein the modulation frequency band of the modulated laser is a frequency band in which the ratio of the analog detection signal before modulation processing to the demodulated analog signal after demodulation processing is within a predetermined tolerance range.

11. 4. The communication device according to claim 1, wherein the laser receiving device corrects the demodulated analog signal so that the demodulated analog signal coincides with the analog detection signal.

12. The communication device according to any one of claims 1 to 3, further comprising a surface quality estimation unit (81) that estimates the surface quality of the workpiece ground by the grinding wheel based on the demodulated analog signal.

13. The first unit further comprises: A non-contact power receiving unit (102, 105) is disposed inside the cylindrical first unit housing and configured to supply power to the sensor, The communication device according to any one of claims 1 to 3, further comprising a non-contact power supply unit (113, 115) that is integrally provided with the laser receiving device and configured to be able to supply power to the non-contact power receiving unit in a non-contact manner.

14. Further, a second unit (62) is attached to the grinding wheel cover, The second unit is A second unit housing (112) formed in a bottomed cylindrical shape and arranged so that an opening side faces the first unit side; The laser receiving device is disposed inside the cylindrical second unit housing; The communication device according to claim 13 , further comprising: the non-contact power supply unit disposed inside the cylindrical second unit housing.

15. the non-contact power receiving unit is disposed on an opening side of the cylindrical interior of the first unit housing, the non-contact power supply unit is disposed on an opening side of the cylindrical interior of the second unit housing, the modulated laser generator is disposed inside the cylindrical first unit housing on a bottom side of the non-contact power receiving unit, The communication device according to claim 14 , wherein the laser receiving device is disposed inside the cylindrical second unit housing on a bottom side relative to the non-contact power supply unit.