AE signal detection device for grinding wheels

Abstract

To provide an AE signal detector which suppresses occurrence of data loss in the AE signal output from a radio transmission circuit even when a grinding processing tool rotates at a high speed.SOLUTION: An AE signal detector comprises: an AE sensor 24; an A / D converter; and an electronic circuit storage case 30 which rotates a radio transmission circuit 48 with a grind stone 14, and the AE signal detector 10 for a grind stone 14 has a reception circuit on a non-rotation member. A transmission module included in the radio transmission circuit 48 is arranged at a position where centrifugal force applied to the transmission module becomes 14 N or smaller. Therefore, the centrifugal force applied to the transmission module is suppressed, even in high speed rotation, data loss in the AE signal which is transmitted by radio transmission, from the transmission module, can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an AE signal detection device for a grinding wheel that detects elastic waves generated from a grinding point of a grinding wheel and outputs an AE signal. [Background technology]

[0002] In order to determine or monitor the grinding surface condition or dressing surface condition of a grinding tool, such as grinding burn, clogging, sharpness of the grinding wheel, and the peripheral surface condition of the grinding wheel, when a grinding wheel having a segment-shaped grinding wheel attached to the outer peripheral surface of a wheel core is used as the grinding tool, an AE signal detection device is known that detects elastic waves emitted from the grinding surface associated with the crushing of abrasive grains constituting the grinding wheel and outputs an AE signal (acoustic emission signal: vibration wave having a relatively high frequency, for example, 100 kHz or more, which is an ultrasonic region). For example, the AE signal detection device for a grinding wheel described in Patent Document 1 and Patent Document 2 is such an AE signal detection device for a grinding wheel.

[0003] Patent Documents 1 and 2 describe that an AE signal detection device is provided in a wheel core that rotates together with the grinding wheel, the AE signal detection device including an AE sensor provided in the wheel core for detecting elastic waves generated in the grinding wheel and outputting an AE signal, and a wireless transmission circuit for converting the AE signal output from the AE sensor into a wireless signal and outputting it from an antenna, and the digitized AE signal is subjected to frequency analysis to determine or evaluate the grinding surface condition of the vitrified grinding wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-69638 A [Patent Document 2] JP 2020-69639 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the rotation speed of the grinding wheel reaches a certain level or higher, centrifugal force is applied to the AE signal detection device rotating together with the grinding wheel, and data loss, known as packet loss, occurs in the AE signal transmitted from the wireless transmission circuit, making the AE signal unstable. As a result, it may be impossible to determine or evaluate the grinding surface condition of the grinding wheel using the AE signal.

[0006] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide an AE signal detection device that suppresses the occurrence of data loss in the AE signal output from a wireless transmission circuit even when the grinding wheel is rotating at high speed. [Means for solving the problem]

[0007] The present inventors have conducted various studies in light of the above circumstances, and have found that by moving the mounting position of a wireless transmission circuit, which converts an AE signal output from an AE sensor into a wireless signal and outputs it from an antenna, toward the center of rotation of the grinding tool and within a certain distance from the center of rotation, the occurrence of data loss in the AE signal wirelessly transmitted from the wireless transmission circuit can be suppressed even at high speed rotation. The present invention was made based on this finding.

[0008] That is, the gist of the first invention is a grinding wheel having an AE sensor which receives elastic waves generated in an annular grinding wheel and outputs an AE signal, an A / D converter which converts the AE signal from an analog signal to a digital signal, a wireless transmission circuit which wirelessly transmits the digitally converted AE signal output from the A / D converter, and a constant-voltage power supply circuit which supplies constant-voltage power to the A / D converter and the wireless transmission circuit, on a rotating member which rotates together with the grinding wheel, and a receiving circuit which receives the AE signal wirelessly transmitted from the wireless transmission circuit, on a non-rotating member. The AE signal detection device includes a non-contact power supply device having a power supply coil fixedly provided on the non-rotating member and driven by a drive current of a predetermined frequency converted from a commercial power source, and a power receiving coil provided on the rotating member in a state of being magnetically coupled to the power supply coil, the non-contact power supply device supplying power to the constant voltage power supply circuit provided on the rotating member, the wireless transmission circuit including an antenna and a transmission module configured in accordance with the IEEE802.11 standard, the transmission module being disposed at a position where the centrifugal force acting on the transmission module is 14 N or less. The A / D converter, the wireless transmission circuit, and the constant voltage power supply circuit are integrally mounted on a common circuit board and housed in an electric circuit housing case fixed to a rotating shaft via a fixture in a state spaced apart from an end of the rotating shaft supporting the grinding wheel in the direction of the rotation center line of the rotating shaft. The reason is that

[0011] No. 2 The gist of the invention is as follows: 1 In the invention, the power supply coil and the power receiving coil are arranged coaxially about the rotation center line and opposite each other at a predetermined distance in the direction of the rotation center line, and the power receiving coil is attached to the side opposite the rotation axis of the electrical circuit housing case.

[0012] No. 3 The gist of the invention is as follows: 1st invention or 2nd invention In the present invention, the transmission module transmits the digitally converted AE signal in packet form via an antenna over a wireless LAN using a UDP protocol. Effect of the Invention

[0013] According to the grinding wheel AE signal detection device of the first invention, the wireless transmission circuit is equipped with an antenna and a transmission module configured in accordance with the IEEE802.11 standard, and the transmission module is disposed at a position where the centrifugal force acting on the transmission module is 14 N or less. Therefore, the centrifugal force acting on the transmission module is suppressed, and data loss in the AE signal wirelessly transmitted from the wireless transmission circuit is suppressed even at high speed rotation. The present invention also includes a non-contact power supply device that has a power supply coil that is fixedly provided on the non-rotating member and driven by a drive current of a predetermined frequency converted from a commercial power source, and a power receiving coil that is provided on the rotating member and magnetically coupled to the power supply coil, and supplies power to a constant voltage power supply circuit provided on the rotating member. This eliminates the need to mount a bulky storage battery on the rotating member that rotates together with the grinding wheel. Furthermore, the A / D converter, the wireless transmission circuit, and the constant-voltage power supply circuit are mounted integrally on a common circuit board and housed in an electric circuit housing case fixed to the rotating shaft via a fixture in a state spaced apart from the end of the rotating shaft supporting the grinding wheel in the direction of the rotation center line of the rotating shaft. As a result, since the electric circuit housing case is fixed to the rotating shaft via a fixture in a state spaced apart from the end of the rotating shaft supporting the grinding wheel in the direction of the rotation center line, the internal space of the electric circuit housing case that houses the transmission module has a small diameter, and the transmission module can be brought closer to the rotation center line.

[0016] No. 2 According to the grinding wheel AE signal detection device of the present invention, the power supply coil and the power receiving coil are arranged coaxially with respect to the rotation center line and opposed to each other at a predetermined distance in the direction of the rotation center line, and the power receiving coil is attached to the opposite side of the electric circuit housing case from the rotation shaft side, thereby making the non-contact power supply device compact.

[0017] No. 3 According to the grinding wheel AE signal detection device of the present invention, the transmission module transmits the digitally converted AE signal via an antenna over a wireless LAN using UDP protocol in packet communication, thereby enabling high-speed wireless data transmission. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram illustrating a configuration of a grinding apparatus including an AE signal detection device for a grinding wheel according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the configuration of an AE signal detection device for the grinding wheel in FIG. [Diagram 3] 3 is a cross-sectional view showing an electric circuit housing case provided in the AE signal detection device for the grinding wheel of FIG. 2, taken along a cross section perpendicular to the center line of rotation of the grinding wheel. [Figure 4] 3 is a cross-sectional view showing an electric circuit housing case provided in the AE signal detection device for the grinding wheel of FIG. 2, taken along a cross section including the center line of rotation of the grinding wheel. [Diagram 5] 13A and 13B are diagrams illustrating a communication device embedding plate that allows the transmission module to be mounted at multiple radial distances from the rotation center line of the grinding wheel. [Figure 6] 6 is a graph showing, in a comparative manner, data loss rates measured for a plurality of types of centrifugal forces of a transmission module using the communication device embedding board shown in FIG. 5 . [Figure 7] 4 is a cross-sectional view of an electric circuit housing showing an example in which the antenna is arranged differently, and corresponds to FIG. 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An embodiment of the present invention will be described in detail below with reference to the drawings. Note that in the following embodiment, the drawings are for explaining the main parts related to the invention, and the dimensions and shapes are not necessarily drawn accurately. EXAMPLES

[0020] Fig. 1 is a diagram illustrating the configuration of a grinding machine 12 equipped with an AE signal detector 10 that detects elastic waves generated in a grinding wheel 14 during grinding and outputs an AE signal. In Fig. 1, the grinding machine 12 uses an annular grinding wheel 14 in which abrasive grains 14a, such as general abrasive grains such as fused alumina-based abrasive grains, silicon carbide-based abrasive grains, and ceramic abrasive grains, or CBN abrasive grains and superabrasive grains such as diamond abrasive grains, are bonded by a bonding material 14b, such as a vitrified bond or metal bond. The grinding wheel 14 is, for example, an integrally molded annular general grinding wheel that does not include a base metal (wheel core).

[0021] 2 shows the mounting structure of the grinding wheel 14 and the configuration of the AE signal detection device 10. As shown in FIG. 2, a male thread 16b is formed on the end of the rotating shaft 16 of the grinding device 12 that is rotated around a rotation center line C1. The grinding wheel 14 is fastened via a washer 26 and a movable flange 20 by a nut 22 screwed onto the male thread 16b of the rotating shaft 16, so that the grinding wheel 14 is mounted in a state of being sandwiched and pressed between a fixed flange 18 made of iron and the movable flange 20 mounted on the end of the rotating shaft 16. The fixed flange 18 includes a cylindrical portion 18b tapered and fitted to a tapered portion 16a formed on the end of the rotating shaft 16, and a fixed flange portion 18a which is a disk portion protruding in the radial direction (outer periphery side) from one end of the cylindrical portion 18b.

[0022] The moving flange 20 has a through hole 20a that is slidably fitted into the cylindrical portion 18b concentrically with the rotation center line C1, and a moving flange portion 20b that is a disk portion that is in close contact with the grinding wheel 14. When the nut 22 is screwed onto the male thread 16b of the rotating shaft 16, the moving flange 20 is pressed via the washer 26, and the grinding wheel 14 is fixed in a clamped state between the fixed flange portion 18a and the moving flange portion 20b. The grinding wheel 14 grinds the outer peripheral surface of a columnar workpiece W, for example, as shown in FIG. 1.

[0023] The movable flange 20 integrally comprises a cylindrical outer peripheral wall 20c, a bottom wall 20d that closes one end of the outer peripheral wall 20c and is brought into close contact with the grinding wheel 14, and a cylindrical inner peripheral wall 20e that is concentric with the outer peripheral wall 20c, and has an annular storage space 20f formed therein that opens to the side opposite the grinding wheel 14. The AE sensor 24 is fixed to the inner peripheral surface of the outer peripheral wall 20c in the storage space 20f, and detects elastic waves transmitted from the grinding point of the grinding wheel 14 to the outer peripheral wall 20c. No electric circuit components such as a transmitting circuit or a storage battery are provided in the storage space 20f of the movable flange 20.

[0024] The AE sensor 24 detects extremely high-frequency acoustic emissions, which are generated when the abrasive grains 14a contained in the grinding wheel 14 are crushed and which are in the elastic vibration range of the ultrasonic region of, for example, 20 kHz or more, and which propagate within the grinding wheel 14, through the movable flange 20 in close contact with the grinding wheel 14, and outputs an AE signal, which is an analog electrical signal representing the crushing vibration. The AE sensor 24 has a receiving plate (not shown) at one end for detecting elastic waves, and is equipped with a mechanical / electrical conversion element, such as a piezoelectric element, which converts the mechanical vibration received by the receiving plate into an AE signal and outputs it.

[0025] 2, the nut 22 is located on the opposite side of the fixed flange 18 with respect to the grinding wheel 14. On the opposite side of the nut 22 from the grinding wheel 14, a cylindrical electric circuit housing case 30 with a bottom is provided concentrically with the rotation center line C1 and supported by the rotating shaft 16, which is a rotating member, via a plurality of support shafts (fixtures) 28 (four in this embodiment). The electric circuit housing case 30 has a radial dimension that is sufficiently smaller than the fixed flange 18 and the movable flange 20, is smaller than the outer peripheral surface of the inner peripheral wall 20e of the movable flange 20, and has an outer diameter equivalent to that of the nut 22.

[0026] Fig. 3 shows a cross section perpendicular to the rotation center line C1 of the electric circuit housing case 30, which is a rotating member, and Fig. 4 shows a cross section including the rotation center line C1 of the electric circuit housing case 30. As shown in Fig. 4, the electric circuit housing case 30 is integrally provided with a cylindrical outer peripheral wall 30a and a bottom wall 30b that closes one end of the outer peripheral wall 30a on the grinding wheel 14 side. A constant voltage power supply circuit 42, a preamplifier 44, an A / D converter 46, and a transmission circuit 48 are housed in the electric circuit housing case 30 together with a common circuit board 36 that supports them.

[0027] The circuit board 36 is fastened to the bottom wall 30b by a plurality of screws 38. In addition, the AE signal output from the AE sensor 24 is input to the preamplifier 44 via lead wires 44a, and the AE signal amplified by the preamplifier 44 is converted from an analog signal to a digital signal by an A / D converter 46. The AE signal digitized by the A / D converter 46 is input to a transmission circuit 48 and transmitted as a radio wave signal from an antenna 52. The constant voltage power supply circuit 42, the preamplifier 44, the A / D converter 46, and the transmission circuit 48 are appropriately connected together by a wiring pattern (not shown) provided on the circuit board 36.

[0028] The A / D converter 46 has high resolution and converts the AE signal into a digital signal at a sampling period of, for example, 10 μs (microseconds) or less, preferably 5 μs or less, and more preferably 1 μs or less. The shorter (faster) the sampling period of the A / D converter 46, the clearer the first frequency band B1 (described below) associated with grain spillage (abrasive grain breakage) and the second frequency band B2 (described below) associated with frictional vibration and elastic vibration caused by contact (rubbing) between the abrasive grains and the workpiece. In the following examples, the sampling period of the A / D converter 46 is 1 μs.

[0029] The transmitting circuit 48 includes a transmitting module 50 and an antenna 52. The transmitting module 50 is disposed on the circuit board 36 at a position where the centrifugal force acting on the transmitting module 50 is 14 N or less. The transmitting module 50 communicates the AE signal, which is a digital signal, in packets via the antenna 52 at a transmission frequency of about 2400 MHz using a protocol known as UDP (User Datagram Protocol) on a wireless LAN. The transmitting module 50 is configured in compliance with, for example, the IEEE802.11 standard, and is preferably a Wi-Fi (registered trademark) communication module.

[0030] An opening 30c is provided penetrating the cylindrical outer peripheral wall 30a of the electric circuit housing case 30 to allow the passage of radio waves transmitted from the antenna 52. A cover (not shown) made of a material that allows radio waves to pass through, such as a synthetic resin or an inorganic material, is fitted into the opening 30c. Instead of forming this opening 30c, the entire outer peripheral wall 30a may be made of a synthetic resin.

[0031] Returning to Fig. 2, a power supply coil 56 and a coil drive circuit 58 that converts a commercial power source into a drive current of a predetermined frequency for driving the power supply coil 56 and drives the power supply coil 56 are fixed to the tip of the fixed arm 54, which is a non-rotating member and is fixed in position. The power receiving coil 60 is fixed to the electric circuit housing case 30 on the side opposite the grinding wheel 14 and is rotatable together with the grinding wheel 14. The power receiving coil 60 and the power supply coil 56 are provided on the electric circuit housing case 30 and the tip of the fixed arm 54, respectively, so as to be concentric with the rotation center line C1 and to face each other with a small gap (predetermined distance) G1 in the direction of the rotation center line C1, and are magnetically coupled to each other.

[0032] 3 converts the power supplied from the power receiving coil 60 into constant-voltage power and supplies it to the preamplifier 44, the A / D converter 46, the transmission circuit 48, etc. The constant-voltage power supply circuit 42, the power receiving coil 60, the coil drive circuit 58, and the power supply coil 56 function as a non-contact power supply device 62 of this embodiment.

[0033] 1, the control box (non-rotating member) (not shown) of the grinding device 12 is provided with a receiving circuit 68 having an antenna 66 for receiving the AE signal wirelessly transmitted from the antenna 52, and an arithmetic and control device 72 for processing the AE signal received in the receiving circuit 68. The AE signal detection device 10 includes a non-contact power supply device 62, the receiving circuit 68 having the antenna 66, the AE sensor 24, and a constant-voltage power supply circuit 42, a preamplifier 44, an A / D converter 46, a transmitting circuit 48, and a transmitting module 50 within the electric circuit housing case 30.

[0034] The arithmetic and control device 72 is an electronic control device, i.e., a so-called microcomputer, including a CPU, ROM, RAM, interface, etc., and the CPU utilizes the temporary storage function of the RAM and processes input signals according to a program previously stored in the ROM to calculate numerical values, graphs, figures, etc. representing the grinding surface condition in order to determine the dressing surface condition, and outputs them from the surface condition display device 70, which also functions as a grinding surface condition display device, and transmits them to the grinding control device 94 described later.

[0035] The arithmetic and control device 72 functionally comprises a frequency analysis unit 74, a grinding surface condition output unit 76, and a dressing surface condition output unit 78. The frequency analysis unit 74 repeatedly performs frequency analysis (FFT) of the AE signal input from the A / D converter 46 during grinding of the workpiece W or during dressing of the grinding wheel 14, and generates a frequency spectrum in which various signal powers indicating the magnitude of frequency components are shown on the frequency axis (horizontal axis) as peak waveforms for each frequency in a two-dimensional coordinate system with the vertical axis indicating signal power and the horizontal axis indicating frequency.

[0036] The grinding surface condition output unit 76 calculates, from the frequency spectrum during grinding of the workpiece W, a first signal strength SP1 for a preset first frequency band B1 having a center frequency of, for example, 32.5 kHz, for example, a first signal strength SP1 for the first frequency band B1 of 20 to 35 kHz, and a second signal strength SP2 for a preset second frequency band B2 having a center frequency of, for example, 55 kHz, for example, a second signal strength SP2 for the second frequency band B2 of 40 to 60 kHz. The first signal strength SP1 and the second signal strength SP2 may be instantaneous values, but in order to stably grasp the dulling or the overflow, it is preferable to use an integral value or a moving average value within a predetermined period, for example, a frequency analysis period, which is set sufficiently longer than the sampling period of the A / D converter 46.

[0037] During the dressing of the grinding wheel 14 using the dresser 90, the dressing surface condition output unit 78, like the grinding surface condition output unit 76, calculates from the frequency spectrum a first signal strength SP1 for a preset first frequency band B1 including 32.5 kHz at its center, for example, the first frequency band B1 of 25 to 35 kHz, and a second signal strength SP2 for a preset second frequency band B2 including 55 kHz at its center, for example, the second frequency band B2 of 40 to 60 kHz. The first signal strength SP1 and the second signal strength SP2 may be instantaneous values, but in order to stably grasp the dulling or the overflow, preferably, an integral value or a moving average value within a predetermined period, for example, a frequency analysis period, which is set sufficiently longer than the sampling period of the A / D converter 46, is used.

[0038] The grinding surface condition output unit 76, during grinding of the workpiece W, and the dressing surface condition output unit 78, during dressing of the grinding wheel 14, calculates a dressing surface condition evaluation value, such as an integral value of the signal intensity over a predetermined period or a related value (e.g., a level value) related to the moving average value, or the signal intensity ratio SR (= SP1 / SP2) or a related value thereof (e.g., a level value) based on at least one of the first signal intensity SP1 and the second signal intensity SP2, and outputs it to the surface condition display device 70.

[0039] As a result, at least one of the first signal intensity SP1 and the second signal intensity SP2, the signal intensity ratio SR, or a value related thereto is displayed as the grinding surface condition evaluation value or the dressing surface condition evaluation value on the surface condition display device 70. When one of the first signal intensity SP1 and the second signal intensity SP2 is used, the grinding surface condition evaluation value or the dressing surface condition evaluation value may be the signal intensity value of one of the first signal intensity SP1 and the second signal intensity SP2 itself, or may be a value converted into an index value that is easy to grasp, such as a level value.

[0040] As shown in FIG. 1, the grinding device 12 includes a spindle drive motor 82 that rotates the rotating shaft 16 to which the grinding wheel 14 is attached, a workpiece rotation drive motor 84 that rotates the cylindrical workpiece W, a workpiece movement motor 86 that moves the workpiece W in the radial direction to press the grinding wheel 14 against the outer circumferential surface of the cylindrical workpiece W, a dresser drive motor 88 that rotates the dresser 90, a dresser feed motor 92 that feeds the dresser 90 in the direction of its rotation center line C1, and a grinding control device 94.

[0041] The grinding control device 94 is composed of a microcomputer similar to that of the arithmetic and control device 72, and functionally includes an automatic grinding control unit 96 and a dressing control unit 98. When the automatic grinding control unit 96 receives a grinding start command signal, it grinds the workpiece W by rotating and relatively moving the grinding wheel 14 and the workpiece W in a preset operation, and when grinding of the workpiece W is completed, it stops the rotation of the workpiece W and returns it to its original position.

[0042] The automatic grinding control unit 96 automatically controls the spindle drive motor 82, the workpiece rotation drive motor 84, and the workpiece movement motor 86 in the process of grinding the workpiece W based on the actual first signal intensity SP1, second signal intensity SP2, or signal intensity ratio SR (=SP1 / SP2) output from the dressing surface condition output unit 78 so that the grinding surface condition indicated by the actual evaluation value for the workpiece W becomes the grinding surface condition indicated by the preset target evaluation value. For example, the automatic grinding control unit 96 sets the target signal intensity ratio SRT to a value that provides a good balance between glazing and overflow, and automatically adjusts the grinding conditions so that the actual signal intensity ratio SR sequentially output in real time from the dressing surface condition output unit 78 coincides with the target signal intensity ratio SRT preset to, for example, about 0.55.

[0043] The inventors analyzed the relationship between the loss of data (e.g., packet loss) representing the AE signal contained in the radio waves transmitted from the transmitting circuit 48 including the transmitting module 50 and the mounting position of the transmitting module 50 (the distance from the rotation center line C1) as follows.

[0044] First, as shown in Figure 5, a communication device embedding plate MB capable of holding the transmission module 50 in an embedded state at three different positions, 50 mm, 70 mm, and 130 mm away from the rotation center line C1, was created, and the communication device embedding plate MB was fixed concentrically to the rotation center line C1 via four bolts BT on the end face of the rotation shaft 16 so that it was in the same position as the electrical circuit housing case 30 in Figure 2.

[0045] Next, when the spindle 16, which is the main shaft, was driven by the spindle drive motor 82 to rotate about the rotation center line C1 at the same rotation speed as that during grinding of the grinding wheel 14, i.e., 3773 rpm, the data loss rate of the AE signal contained in the radio wave transmitted from the transmission circuit 48 including the transmission module 50 was measured for each of the cases where the distance from the rotation center line C1 of the transmission module 50 was 50 mm, 70 mm, and 130 mm. Here, the distance from the rotation center line C1 of the transmission module 50 refers to the distance between the center of the transmission module 50 and the rotation center line C1. The weight of the transmission module 50 was 1.75 g.

[0046] The data loss rate was measured as a percentage of the number of missing data obtained by subtracting the number of actually received data from the total number of theoretical data when vibration data that was A / D converted with a resolution of 12 bits and a sampling period of 1 μs was measured for 60 seconds.

[0047] FIG. 6 is a graph showing the measurement results of the data loss rate. In FIG. 6, when the communication device embedding plate MB was in a rotation stop state, that is, when the centrifugal force applied to the transmission module 50 was 0N, the data loss rate was 0%. Also, when the distance from the rotation center line C1 of the transmission module 50 was 50 mm, that is, when the centrifugal force applied to the transmission module 50 was 14N, the data loss rate was 0%. However, when the distance from the rotation center line C1 of the transmission module 50 was 70 mm, that is, when the centrifugal force applied to the transmission module 50 was 19N, the data loss rate was 62.3%. Also, when the distance from the rotation center line C1 of the transmission module 50 was 130 mm, that is, when the centrifugal force applied to the transmission module 50 was 36N, the data loss rate was 63.0%. Thus, a data loss rate of 0% was obtained within a range of 50 mm or less from the rotation center line C1 of the grinding wheel 14, that is, when the centrifugal force applied to the transmission module 50 was 14N or less.

[0048] As described above, according to the AE signal detection device 10 for the grinding wheel 14 of this embodiment, the AE sensor 24 that receives elastic waves generated in the annular grinding wheel 14 and outputs an AE signal, the A / D converter 46 that digitally converts the AE signal from an analog signal to a digital signal, and the transmission circuit (wireless transmission circuit) 48 that wirelessly transmits the digitally converted AE signal output from the A / D converter 46 are provided in an electric circuit housing case (rotating member) 30 that rotates together with the grinding wheel 14, and the receiving circuit 68 that receives the AE signal wirelessly transmitted from the transmission circuit 48 is provided in a control box that is a non-rotating member, and the AE signal detection device 10 for the grinding wheel is provided with a transmitting module 50 included in the transmitting circuit 48, which is disposed at a position where the centrifugal force acting on the transmitting module is 14 N or less. Therefore, the centrifugal force acting on the transmitting module 50 is suppressed, and therefore the occurrence of data loss in the AE signal wirelessly transmitted from the transmitting circuit 48 including the transmitting module 50 is suppressed even at high speed rotation.

[0049] Furthermore, the AE signal detection device 10 of this embodiment includes a constant-voltage power supply circuit 42 that is provided inside the electric circuit housing case 30, which is a rotating member that rotates together with the rotating shaft 16, and supplies power to a transmitting circuit 48 including a transmitting module 50, and a non-contact power supply device 62 that has a power supply coil 56 provided in the position-fixed electric circuit housing case 30 and a power receiving coil 60 magnetically coupled to the power supply coil 56, and supplies power to the constant-voltage power supply circuit 42. This makes it unnecessary to mount a bulky storage battery in the electric circuit housing case 30 that rotates together with the grinding wheel 14.

[0050] Moreover, according to the AE signal detection device of this embodiment, the A / D converter 46, the transmitting circuit 48 including the transmitting module 50, and the constant voltage power supply circuit 42 are housed in an electric circuit housing case 30 fixed to the rotating shaft 16 via a support shaft (fixing device) 28 in a state spaced apart in the direction of the rotation center line C1 from the axial end of the rotating shaft 16 supporting the grinding wheel 14, while being integrally mounted on a common circuit board 36. As a result, since the electric circuit housing case 30 is fixed to the rotating shaft 16 via the support shaft 28 in a state spaced apart in the direction of the rotation center line C1 from the axial end of the rotating shaft 16 supporting the grinding wheel 14, the internal space of the electric circuit housing case 30 housing the transmitting module 50 has a small diameter, and the transmitting module 50 can be brought closer to the rotation center line C1.

[0051] Furthermore, according to the AE signal detection device 10 of this embodiment, the power supply coil 56 and the power receiving coil 60 are arranged coaxially with respect to the rotation center line C1 and opposed to each other at a predetermined distance G1 in the direction of the rotation center line C1, and the power receiving coil 60 is attached to the side opposite to the rotation shaft 16 side of the electric circuit housing case 30. This makes it possible to make the non-contact power supply device 62 compact.

[0052] Moreover, according to the AE signal detection device 10 of this embodiment, the transmission module 50 transmits the digitally converted AE signal in packet form via the antenna 52 over a wireless LAN using the UDP protocol, thereby enabling high-speed wireless data transmission.

[0053] Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other embodiments.

[0054] For example, in the above-described embodiment, the AE sensor 24 is provided on the movable flange 20, but it may be provided on the fixed flange 18. Furthermore, when a grinding wheel formed by attaching a plurality of segmented grindstones to the outer peripheral surface of a base metal is used instead of the grinding wheel 14, the AE sensor 24 may be provided on the base metal. Furthermore, the antenna 52 is provided on the transmitting circuit 48, but as shown in FIG. 7, the antenna 52 may be provided on a transmitting module 50 included in the transmitting circuit 48.

[0055] In addition, in the above-described embodiment, the non-contact power supply device 62 was used as the main power source for the constant voltage power supply circuit 42 provided in the electric circuit housing case 30, but instead of the non-contact power supply device 62, a storage battery may be provided in the electric circuit housing case 30.

[0056] In addition, in the above-described embodiment, a non-contact power supply device 62 including a magnetically coupled power supply coil 56 and power receiving coil 60 is used, but a non-contact power supply device including a solar cell that generates electricity by receiving light from a floodlight device, or a non-contact power supply device including an antenna device that generates electricity by receiving microwaves, etc. may also be used.

[0057] It should be noted that the above is merely one embodiment of the present invention, and various modifications can be made to the present invention without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0058] 10: AE signal detection device 14: Grinding wheel 16: Rotating shaft (rotating part) 24:AE sensor 28: Support shaft (fixture) 30: Electric circuit housing case (rotating part) 36: Circuit board 42: Constant voltage power supply circuit 48: Transmitter circuit (radio transmitter circuit) 50: Transmitting module 52: Antenna 56: Power supply coil 60: Receiving coil 62: Non-contact power supply device 68: Receiving circuit C1: Center line of rotation

Claims

1. An AE signal detection device for a grinding wheel, comprising: an AE sensor that receives elastic waves generated in an annular grinding wheel and outputs an AE signal; an A / D converter that digitally converts the AE signal from an analog signal to a digital signal; a wireless transmission circuit that wirelessly transmits the digitally converted AE signal output from the A / D converter; and a constant-voltage power supply circuit that supplies constant-voltage power to the A / D converter and the wireless transmission circuit, on a rotating member that rotates together with the grinding wheel, and a receiving circuit that receives the AE signal wirelessly transmitted from the wireless transmission circuit, on a non-rotating member, a contactless power supply device including a power supply coil fixedly provided on the non-rotating member and driven by a drive current of a predetermined frequency converted from a commercial power source, and a power receiving coil provided on the rotating member in a state of being magnetically coupled to the power supply coil, the contactless power supply device supplying power to the constant voltage power supply circuit provided on the rotating member, The wireless transmission circuit includes an antenna and a transmission module configured in accordance with the IEEE 802.11 standard; the transmission module is disposed at a position where a centrifugal force acting on the transmission module is 14 N or less; The A / D converter, the wireless transmission circuit, and the constant voltage power supply circuit are integrally mounted on a common circuit board and housed in an electric circuit housing case fixed to a rotating shaft via a fixture in a state spaced apart from an end of the rotating shaft supporting the grinding wheel in the direction of the rotation center line of the rotating shaft.

1. A grinding wheel AE signal detection device comprising:

2. The power supply coil and the power receiving coil are arranged coaxially with respect to the rotation center line and opposed to each other at a predetermined distance in the direction of the rotation center line, and the power receiving coil is attached to the side of the electric circuit housing case opposite to the rotation shaft side.

2. The AE signal detection device for a grinding wheel according to claim 1.

3. The transmission module transmits the digitally converted AE signal via an antenna in the form of packets on a wireless LAN using a UDP protocol.

3. The AE signal detection device for a grinding wheel according to claim 1 or 2.

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