State detection device, control device, state detection method, and control method

Abstract

This state detection device (10A) is characterized by comprising: a measurement unit (2) that measures the luminance of light emitted, in accordance with stress generated on a surface of an object (O), by a stress luminescent body (L) contained in the surface of the object (O); and a measurement signal processing unit (3) that detects a temporal change in the luminance of the light on the basis of the measurement result of the measurement unit (2).

Description

State Detection Device, Control Device, State Detection Method, and Control Method

[0001] The present disclosure relates to a state detection device, a control device, a state detection method, and a control method for detecting the state of a measurement object.

[0002] As a method for detecting the state of a measurement object, a method of installing a sensor on the measurement object is common. Further, Patent Document 1 discloses a technique for detecting the vibration state of a measurement object by analyzing an image obtained by photographing the measurement object. By using an image, it is not necessary to install a sensor on the measurement object, and it becomes possible to detect the state of the measurement object non-contact.

[0003] International Publication No. 2005 / 083400

[0004] However, in the above conventional technique, there is a problem that vibration cannot be detected when the amplitude of the generated vibration is smaller than the spatial resolution of the image sensor corresponding to each pixel.

[0005] The present disclosure has been made in view of the above, and an object thereof is to obtain a state detection device capable of improving the detection accuracy of the state of a measurement object.

[0006] In order to solve the above-described problems and achieve the object, a state detection device according to the present disclosure includes a measurement unit that measures the luminance of light emitted by a stress luminescent body included in the surface of a measurement object in response to stress generated on the surface of the measurement object, and a measurement signal processing unit that detects a change over time in the luminance of the light based on the measurement result of the measurement unit.

[0007] According to the present disclosure, there is an effect that it becomes possible to improve the detection accuracy of the state of a measurement object.

[0008] Figure 1 shows an example of the configuration of the state detection device according to Embodiment 1. A flowchart for explaining the state detection method according to Embodiment 1 shows an example of the display of the state detection result shown by the display unit. An explanatory diagram of an example of a measurement target. Figure 4 shows an example of the display of the state detection result of the measurement target shown. Figure 2 shows an example of the configuration of the state detection device according to Embodiment 2. A diagram showing an example of the configuration of a machine tool. A diagram showing dedicated hardware for realizing the functions of the state detection device. A diagram showing an example of the configuration of a control circuit for realizing the functions of the state detection device.

[0009] The state detection device, control device, state detection method, and control method according to embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited by these embodiments.

[0010] Embodiment 1. Figure 1 shows an example of the configuration of the state detection device 10A according to Embodiment 1. The state detection device 10A is a device that detects the state of the object to be measured O. The surface of the object to be measured O contains a stress-emitting element L.

[0011] A stress-emitting material L is a material capable of emitting excitation energy as light in response to external mechanical stimuli. Examples of mechanical stimuli include impact, compression, tension, and bending. As a stress-emitting material L, for example, europium-doped strontium aluminate can be used. When europium-doped strontium aluminate is excited by light such as ultraviolet light, carriers released from europium are trapped in the material, and light is emitted when these carriers are released by mechanical stimuli such as stress. Therefore, when a mechanical stimulus is applied while excitation light is shone on the stress-emitting material L, excitation and light emission occur simultaneously, allowing for a continuous light emission phenomenon.

[0012] The stress-emitting element L may be mixed with an adhesive and applied to the surface of the object to be measured O, or a sheet with the stress-emitting element L pre-applied, or a sheet created by mixing the stress-emitting element L into a substrate, may be bonded to the surface of the object to be measured O.

[0013] The state detection device 10A includes an excitation light irradiation unit 1, a measurement unit 2, a measurement signal processing unit 3, and a display unit 4.

[0014] The excitation light irradiation unit 1 is a light source that emits excitation light with wavelengths capable of exciting the stress emitter L, and its type is not particularly limited. For example, if the stress emitter L is excited by natural light such as sunlight, the state detection device 10A does not need to be equipped with the excitation light irradiation unit 1. Since the excitation wavelengths of currently existing stress emitters L are in the ultraviolet to visible light range, for example, an LED (Light Emitting Diode) light that emits ultraviolet light with a wavelength of 365 nm can be used as the light source for the excitation light irradiation unit 1.

[0015] The measurement unit 2 measures the brightness of the light emitted by the stress-emitting element L in response to the stress generated on the surface of the object to be measured O. The measurement unit 2 is, for example, an illuminance sensor. The measurement unit 2 can measure the change in light emission intensity from the object to be measured O by converting the amount of light incident on the light-receiving part of a sensor, such as a PIN photodetector, into an electrical signal and measuring it. Here, it is desirable that the response time of the sensor be sufficiently shorter than the period of change in the light emission intensity to be measured, and that the direction and degree of convergence of the light generated from the object to be measured O and incident on the light-receiving part do not change significantly during the change in light intensity, i.e., the period of intensity fluctuation. Depending on the strength of the light intensity, a light-collecting means, a diffusion means, etc. may be provided between the object to be measured O and the light-receiving part to adjust the light intensity incident on the light-receiving part. Alternatively, the measurement unit 2 may be a general camera or a high-speed camera equipped with an image sensor in which a plurality of light-receiving elements are arranged in two dimensions and the brightness of the light received by each light-receiving element is output as a measurement result. A high-speed camera is a camera capable of playing back images captured at high speed as if in slow motion, and generally refers to a camera capable of shooting at 1000 fps or higher. The measurement unit 2 may also be an event-based camera. An event-based camera has an image sensor in which multiple light-receiving elements are arranged in two dimensions, and the brightness of the light received by each light-receiving element is converted into a numerical value and output. It can output a dataset as a measurement result that includes the position of the light-receiving element whose brightness has changed by more than a predetermined threshold and the time when the change was detected. The position of the light-receiving element is represented, for example, by the pixel number. Event-based cameras are characterized by high sensitivity to brightness and a very high frame rate. When the measurement unit 2 uses an image sensor, it becomes possible to measure the two-dimensional distribution of light emission intensity.

[0016] The measurement unit 2 may also be equipped with an optical filter that blocks the wavelength band of the excitation light but not the wavelength band of the emission wavelength. For example, if the excitation light irradiation unit 1 is an LED light that generates ultraviolet light with a wavelength of 365 nm, and the emission wavelength of the stress emitter L is 450 nm, the measurement unit 2 may be equipped with an optical low-pass filter that blocks light with wavelengths less than 400 nm.

[0017] The measurement signal processing unit 3 processes the measurement signal output by the measurement unit 2. Specifically, the measurement signal processing unit 3 detects the change in brightness of the light emitted by the stress light emitter L over time, based on the measurement results from the measurement unit 2. When detecting vibration of the object to be measured O, the measurement signal processing unit 3 calculates the period of change in brightness from the measurement results from the measurement unit 2.

[0018] The display unit 4 displays the state of the object to be measured O detected by the measurement signal processing unit 3 using a display screen. The display unit 4 provides a display screen to a display device such as an LCD (Liquid Crystal Display). Here, the display device may be part of the state detection device 10A, or it may be a separate device connected to the state detection device 10A.

[0019] Figure 2 is a flowchart illustrating the state detection method according to Embodiment 1. The state detection method first includes the step of attaching a stress-emitting element L to the surface of the object to be measured O (step S101). If the object to be measured O already contains a stress-emitting element L, the process in step S101 can be omitted. The step of attaching the stress-emitting element L in step S101 may be performed manually by the user of the state detection device 10A, or if the state detection device 10A has a function to attach the stress-emitting element L to the object to be measured O, the state detection device 10A may perform this step.

[0020] Following step S101, the state detection method includes the step of irradiating the object to be measured O with excitation light (step S102). The excitation light irradiation unit 1 irradiates the object to be measured O with excitation light.

[0021] Following step S102, the state detection method includes a step of measuring the brightness of light from the stress light emitter L (step S103). The measurement unit 2 measures the brightness of light emitted by the stress light emitter L excited by the excitation light irradiation unit 1 and outputs the measurement result, which is the measurement signal, to the measurement signal processing unit 3.

[0022] Following step S103, the state detection method includes a step of processing the measurement signal, which is the measurement result (step S104). The measurement signal processing unit 3 detects the change in brightness of the light emitted by the stress light emitter L over time by processing the measurement signal. When the state detection device 10A detects vibration of the object to be measured O, the measurement signal processing unit 3 can calculate the period of vibration of the object to be measured O by calculating the period of change in the brightness of the light emitted by the stress light emitter L.

[0023] Following step S104, the state detection method includes a step of displaying the time-dependent change in the detected brightness (step S105). The display unit 4 can visualize the time-dependent change in the brightness of the light emitted by the stress light emitter L. The display method is not particularly limited. For example, the display unit 4 can represent numerical values ​​such as vibration period and vibration frequency using a color map, grayscale, or the numerical values ​​themselves.

[0024] Figure 3 shows an example of the display of the state detection results shown by the display unit 4. In Figure 3, a grayscale is used to represent the vibration frequency by the intensity of the color. Figure 3 shows an example of displaying the vibration frequencies of three measurement targets O1, O2, and O3. It can be seen that the vibration frequency of measurement target O1 is about 1000 Hz, the vibration frequency of measurement target O2 is about 500 Hz, and the vibration frequency of measurement target O3 is about 100 Hz.

[0025] Although Figure 3 shows an example using grayscale, a color map that represents vibration frequencies by color may also be used. Furthermore, in Figure 3, the entire measurement target O1, O2, and O3 are represented as vibrating, but the vibration frequency may differ even within a single measurement target O.

[0026] Figure 4 is an explanatory diagram of an example of a measurement target object O4. When a plate-shaped measurement target object O4 vibrates, the stress state generated differs between the antinodes and nodes of the vibration. Figure 4 shows an example in which vibration with two antinodes occurs in a plate-shaped measurement target object O4. Of the parts P1 and P2 which are the antinodes of the vibration, in the state shown in Figure 4, part P1 has strong compressive stress, and part P2 has strong tensile stress. In this vibration state, no stress is generated at the parts corresponding to the nodes of the vibration, but stress is generated periodically at the parts P1 and P2 which are the antinodes of the vibration, causing the stress luminescent body L to emit light.

[0027] Figure 5 shows an example of displaying the state detection results of the object O4 shown in Figure 4. Figure 5 is a view of the object O4 shown in Figure 4 from direction A. In Figure 5, the object O4 is referred to as object O4-1, O4-2, and O4-3 depending on its state, but object O4-1, O4-2, and O4-3 refer to different states of the same object O4. Here, an example is shown in which the change in luminescence intensity is displayed directly as the state detection result.

[0028] In the example shown in Figure 5, the two-dimensional distribution of luminescence intensity is shown in grayscale. As a result, the measured object changes from state O4-1, where the stress is maximum at points P1 and P2 corresponding to the antinodes of the vibration, to state O4-2, where the stress at points P1 and P2 is reduced, to state O4-3, where the stress disappears, then the stress at points P1 and P2 increases again, changing back to state O4-2, and finally back to state O4-1, repeating this change periodically.

[0029] Although this example shows a two-dimensional distribution of luminescence intensity, the vibration period may also be displayed for each part of the object O being measured using a grayscale or other method.

[0030] As described above, Embodiment 1 provides a state detection device 10A characterized by comprising: a measurement unit 2 that measures the brightness of light emitted by a stress-emitting element L contained on the surface of an object to be measured O in response to the stress generated on the surface of the object to be measured O; and a measurement signal processing unit 3 that detects the change in brightness of the light over time based on the measurement result of the measurement unit 2. With the state detection device 10A, since it detects the change in brightness of the light emitted by the stress-emitting element L in response to the stress generated on the surface of the object to be measured O, it becomes possible to detect abnormalities even if the brightness of the light reflected by the object to be measured O does not change. This has the effect of improving the accuracy of detecting the state of the object to be measured O.

[0031] Furthermore, the state detection device 10A may include an excitation light irradiation unit 1 that irradiates the stress light emitter L with light of a wavelength that excites the stress light emitter L. As described above, if the stress light emitter L is excited by natural light or light from a lighting fixture installed in the room, the state detection device 10A does not need to include the excitation light irradiation unit 1.

[0032] The measurement unit 2 may be an image sensor in which multiple light-receiving elements are arranged in two dimensions and output the brightness of the light received by each light-receiving element as a measurement result. In this case, it becomes possible to capture the state of the object to be measured O as an image, and even if the location where the abnormality of the object to be measured O occurs is unknown, or if it is not possible to install a sensor on the object to be measured O, it becomes possible to detect the state of the object to be measured O, such as an abnormality. For example, the measurement unit 2 may be a high-speed camera.

[0033] The measurement unit 2 may have an image sensor in which multiple light-receiving elements are arranged in two dimensions, and which converts the brightness of the light received by each light-receiving element into a numerical value and outputs it. The measurement unit 2 may output a dataset as a measurement result to the measurement signal processing unit 3, which includes the position of the light-receiving element whose brightness has changed by more than a predetermined threshold and the time at which the change was detected. For example, the measurement unit 2 is an event-based camera.

[0034] Furthermore, the measurement signal processing unit 3 can detect the period in which vibration or repetitive abnormalities occur in the object O being measured by calculating the period in which the brightness of the light changes.

[0035] The measurement signal processing unit 3 calculates the period of change in brightness at each light-receiving element based on the time at which the brightness of the above-mentioned dataset changes, and the state detection device 10A may further include a display unit 4 that displays the period of change in brightness.

[0036] If the stress-emitting element L is already present on the surface of the object to be measured O, the object to be measured O can be used as is, or the stress-emitting element L may be attached to the surface of the object to be measured O. The method of attaching the stress-emitting element L to the surface of the object to be measured O is not particularly limited. For example, the stress-emitting element L may be coated onto the surface of the object to be measured O, or a sheet containing the stress-emitting element L may be bonded to the surface of the object to be measured O.

[0037] Furthermore, according to Embodiment 1, a state detection method can be provided. The state detection method is characterized by including a measurement step of measuring the brightness of light emitted by a stress-emitting element L contained on the surface of an object to be measured O in accordance with the stress generated on the surface of the object to be measured O, and a state detection step of detecting the change in the brightness of the light over time based on the measurement result of the measurement step.

[0038] Furthermore, in the measurement step, the brightness of light can be measured using an image sensor, such as a high-speed camera, in which multiple light-receiving elements are arranged in two dimensions and the brightness of the light received by each light-receiving element is output as a measurement result. Alternatively, in the measurement step, an image sensor, such as an event-based camera, may be used, in which multiple light-receiving elements are arranged in two dimensions and the brightness of the light received by each light-receiving element is converted into a numerical value and output, and a dataset including the position of the light-receiving element whose brightness has changed by more than a predetermined threshold and the time when the change was detected may be output as the measurement result.

[0039] In the state detection step, the period of change in light intensity can be calculated. Furthermore, if an event-based camera is used, the state detection step may calculate the period of change in brightness at each photodetector based on the time when the brightness of the above dataset changed. The state detection method may further include a display step that displays the period of change in brightness.

[0040] Further, the state detection method may further include a preparation step of attaching a stress luminescent body L to the surface of the measurement object O before the measurement step, and an excitation light irradiation step of irradiating excitation light including light having a wavelength for exciting the stress luminescent body L on the measurement object O.

[0041] Embodiment 2. FIG. 6 is a diagram showing a configuration example of the state detection device 10B according to Embodiment 2. In Embodiment 2, an example in which the state detection device 10B is incorporated in the control device of the machine tool 5 will be described.

[0042] The state detection device 10B is a control device of the machine tool 5. The state detection device 10B includes an excitation light irradiation unit 1, a measurement unit 2, a measurement signal processing unit 3B, a display unit 4, and a control unit 6.

[0043] Here, an example of the machine tool 5 that is the control target will be described. FIG. 7 is a diagram showing a configuration example of the machine tool 5. The machine tool 5 is a machine that processes a workpiece, and for example, is a machining center shown in FIG. 7. Although an example of a machining center is shown here, the machine tool 5 is not limited to such an example, and may be a lathe or the like.

[0044] The machine tool 5 is a vertical machining center with three orthogonal axes. The machine tool 5 includes a spindle control unit 92 configured to include a process control device that controls a spindle 83 of one axis, an X-axis drive unit 93 configured to include a servo control device that drives the X-axis, a Y-axis drive unit 94 configured to include a servo control device that drives the Y-axis, and a Z-axis drive unit 95 configured to include a servo control device that drives the Z-axis. The machine tool 5 drives the tool 76 in the directions of the X-axis and the Z-axis, drives the workpiece 78 placed on the worktable 77 in the direction of the Y-axis, and rotates the tool 76 using the spindle 83 to process the workpiece 78. The machine tool 5 operates according to the control of the control device to process the workpiece 78 into a desired shape.

[0045] The X-axis drive unit 93 includes a motor 71X, a guide mechanism 72X, and a feed screw 73X. The Y-axis drive unit 94 includes a motor 71Y, a guide mechanism 72Y, and a feed screw 73Y. The Z-axis drive unit 95 includes a motor 71Z, a guide mechanism 72Z, and a feed screw 73Z. A rotation angle detector 80X for detecting the rotation angle of the motor 71X is attached to the motor 71X. A rotation angle detector 80Y for detecting the rotation angle of the motor 71Y is attached to the motor 71Y. A rotation angle detector 80Z for detecting the rotation angle of the motor 71Z is attached to the motor 71Z. Hereinafter, when not distinguishing each of the motors 71X, 71Y, and 71Z, a common reference numeral 71 is used for the motors 71X, 71Y, and 71Z, and they are simply referred to as the motor 71. Similarly, when not distinguishing each of the guide mechanisms 72X, 72Y, and 72Z, they are simply referred to as the guide mechanism 72, and when not distinguishing each of the feed screws 73X, 73Y, and 73Z, they are simply referred to as the feed screw 73.

[0046] In the machine tool 5, for each axis, the rotational motion of the motor 71, which is an actuator, is converted by the feed screw 73 into a linear motion in the driving direction of each axis. At this time, since the rotational motion is supported by the guide mechanism 72, the axis has freedom only in the feed direction of the feed screw 73. As a result, in the machine tool 5, a two-degree-of-freedom motion of the tool 76 in the XZ plane combining the linear motions of each axis and a one-degree-of-freedom motion of the workpiece 78 in the Y-axis direction enable a three-degree-of-freedom motion within the three-dimensional space of XYZ, that is, a three-degree-of-freedom motion is realized. The machine tool 5 rotates the tool 76 using the spindle 83 and removes the material of the portion where the workpiece 78 interferes with the tool 76 to process the workpiece 78.

[0047] Returning to the description of FIG. 6. The control unit 6 has a function of controlling the operation of the machine tool 5. The control unit 6 outputs the rotational speed of the spindle 83 of the machine tool 5 to the measurement signal processing unit 3B. The measurement object O is a processing object with a stress luminescent body L attached to its surface, and can be the workpiece 78 shown in FIG. 7. Alternatively, the measurement object O may be the tool 76.

[0048] Even when the state detection device 10B is the control device for the machine tool 5, the state of the object to be measured O can be detected using the same method as in Embodiment 1. Furthermore, in this case, when the object to be measured O is a workpiece 78 or tool 76 that is the workpiece of the machine tool 5, the vibration frequency of the vibration occurring in the object to be measured O can be predicted in advance from the rotational speed of the spindle 83. For this reason, the state detection device 10B has a function to reduce the amount of computation by narrowing down the signal components to be processed to the frequency components in which vibration is expected to occur.

[0049] For example, let's describe a case where the tool 76 attached to the spindle 83 is an end mill and the workpiece 78 is cut. The machine tool 5 is equipped with motors 71X, 71Y, and 71Z that drive the spindle 83 and the feed axis. The frequency F of the vibration generated during end milling consists of a component obtained from the spindle speed S (rpm) by the following formula (1), and its multiple components.

[0050] F=S / 60...(1)

[0051] In end milling, forced vibrations are expected to occur in the object due to the cutting force acting as the excitation force. Therefore, the frequency of the vibrations that will occur can be predicted in advance using the above formula (1). Under these conditions, it is not necessary to perform frequency analysis across the entire frequency band up to the Nyquist frequency. The computational load can be reduced by narrowing down the signal to be processed to specific frequency components where vibrations are expected to occur.

[0052] For example, the measurement signal processing unit 3B can narrow down the signal to be processed from the measurement signals input as measurement results to a target signal that contains at least one frequency component from among the frequency component of the rotational speed of the spindle 83 and the frequency component of an integer multiple of the rotational speed of the spindle 83, and calculate the vibration period by performing a discrete Fourier transform on the target signal.

[0053] For example, if the measurement signal processing unit 3B performs analysis on all frequencies corresponding to the number of data points M of the data subject to frequency analysis, the computational complexity of the discrete Fourier transform is M. 2In the Fast Fourier Transform, the computational complexity is Mlog²(M / 2). In contrast, the computational complexity of analyzing a single frequency is M. Therefore, by narrowing down the frequency components to be processed, the computational complexity becomes the number of frequency components to be processed multiplied by the number of data points M.

[0054] For example, consider the case where the number of data points M = 64. In the usual discrete Fourier transform, the computational complexity is 64. 2 This equals 4096. Also, in a normal Fast Fourier Transform, the computational complexity is 64 × log2(64 / 2) = 320. In contrast, when the measurement signal processing unit 3B narrows down the frequencies to be analyzed to F, 2F, and 3F up to the third harmonic, the computational complexity becomes 3 × 64 = 192.

[0055] In the example shown in Figure 6, the measurement signal processing unit 3B obtains a control value for the rotational speed of the spindle 83 from the control unit 6. However, it is also possible to use an actual measured value that is assumed to be the rotational speed, separate from the control unit 6.

[0056] Furthermore, while Embodiment 2 provides a method for controlling the machine tool 5, the method for controlling the machine tool 5 is the same as the state detection method described in Embodiment 1 using Figure 2, except that in step S104, the frequency components to be processed are narrowed down. Therefore, a detailed explanation is omitted here.

[0057] As described above, in the state detection device 10B according to Embodiment 2, the object to be measured O is a workpiece 78 or tool 76, which is a workpiece installed on a machine tool 5 having a spindle 83 and a feed axis. The measurement signal processing unit 3B narrows down the signal to be processed from the measurement signals input as measurement results to a target signal that includes at least one frequency component from the frequency component of the rotational speed of the spindle 83 and the frequency component of an integer multiple of the rotational speed of the spindle 83. By performing a discrete Fourier transform on the target signal, the period during which the detected light emission intensity changes can be calculated. This makes it possible to reduce the amount of computation.

[0058] Furthermore, according to Embodiment 2, a state detection device 10B is provided, which is a control device for controlling a machine tool 5, and is characterized by comprising: a measurement unit 2 that measures the brightness of light emitted by a stress-emitting element L contained on the surface of a workpiece 78 or tool 76, which is the workpiece object to be processed by the machine tool 5, in accordance with the stress generated on the surface of the workpiece O; and a measurement signal processing unit 3B that detects the change in brightness of light over time based on the measurement result of the measurement unit 2.

[0059] Furthermore, according to Embodiment 2, a control method for controlling the machine tool 5 can be provided. The control method for the machine tool 5 is characterized by including a measurement step of measuring the brightness of light emitted by a stress-emitting element L contained on the surface of a workpiece 78 or tool 76, which is the object to be machined by the machine tool 5, in accordance with the stress generated on the surface of the workpiece 78 or tool 76; and a state detection step of detecting the change in brightness of light over time based on the measurement result of the measurement step.

[0060] Next, the hardware configuration of the state detection devices 10A and 10B according to embodiments 1 and 2 of this disclosure will be described. The functions of the state detection devices 10A and 10B are realized by processing circuits. These processing circuits may be realized by dedicated hardware or by control circuits using a CPU (Central Processing Unit).

[0061] When the above processing circuits are implemented using dedicated hardware, they are implemented by the processing circuit 100 shown in Figure 8. Figure 8 is a diagram showing the dedicated hardware for realizing the functions of the state detection devices 10A and 10B. The processing circuit 100 may be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0062] When the above processing circuit is implemented using a control circuit with a CPU, this control circuit is, for example, a control circuit 101 with the configuration shown in Figure 9. Figure 9 is a diagram showing an example configuration of a control circuit 101 for realizing the functions of state detection devices 10A and 10B. As shown in Figure 9, the control circuit 101 includes a processor 102 and a memory 103. The processor 102 is a CPU, also called a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor), etc. The memory 103 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Registered Trademark) (Electrically EPROM), magnetic disk, flexible disk, optical disk, compact disk, minidisc, DVD (Digital Versatile Disk), etc.

[0063] When the above processing circuit is implemented by the control circuit 101, it is implemented by the processor 102 reading and executing the program corresponding to the processing of each component, which is stored in the memory 103. The memory 103 is also used as temporary memory for each process executed by the processor 102. The program may be provided in a state stored on a storage medium, or it may be provided via a communication channel such as the internet.

[0064] The configurations shown in the embodiments described above are merely examples of the content of this disclosure, and can be combined with other known technologies, combined with other embodiments, and some parts of the configuration can be omitted or modified without departing from the gist of this disclosure.

[0065] For example, in the above embodiment 2, the case in which the object to be measured O is a workpiece of the machine tool 5 was described, but the object to be measured O may be a mechanical structural part of the machine tool 5, or it may be a structure other than the machine tool 5, such as a bridge pier or bridge girder. As described in embodiment 2, when the object to be measured O is a rotating object such as a tool 76, it is difficult to install the sensor because the cable connected to the sensor becomes tangled, so a method of detecting the state without contact, which does not require installing a sensor on the object to be measured O, as in this disclosure, is preferred.

[0066] 1 Excitation light irradiation unit, 2 Measurement unit, 3, 3B Measurement signal processing unit, 4 Display unit, 5 Machine tool, 6 Control unit, 10A, 10B State detection device, 71, 71X, 71Y, 71Z Motor, 72, 72X, 72Y, 72Z Guiding mechanism, 73, 73X, 73Y, 73Z Lead screw, 76 Tool, 77 Work table, 78 Workpiece, 80X, 80Y, 80Z Rotation angle detector, 83 Spindle, 92 Spindle control unit, 93 X-axis drive unit, 94 Y-axis drive unit, 95 Z-axis drive unit, 100 Processing circuit, 101 Control circuit, 102 Processor, 103 Memory, A Direction, F Frequency, L Stress light emitter, M Number of data points, O, O1, O2, O3, O4, O4-1, O4-2, O4-3 Object to be measured, P1, P2 locations, S spindle speed.

Claims

1. A state detection device comprising: a measuring unit that measures the brightness of light emitted by stress-emitting elements contained on the surface of an object to be measured in response to stress generated on the surface of the object to be measured; and a measurement signal processing unit that detects changes in the brightness of the light over time based on the measurement results of the measuring unit.

2. The state detection device according to claim 1, further comprising an excitation light irradiation unit that irradiates the stress light emitter with light of a wavelength that causes the stress light emitter to enter an excited state.

3. The state detection device according to claim 1 or 2, characterized in that the measurement unit is an image sensor in which a plurality of light-receiving elements are arranged in two dimensions and which outputs the brightness of the light received by each light-receiving element as a measurement result.

4. The state detection device according to claim 1 or 2, characterized in that the measurement unit has an image sensor in which a plurality of light-receiving elements are arranged in two dimensions, and which converts the brightness of the light received by each light-receiving element into a numerical value and outputs it, and outputs a dataset including the position of the light-receiving element whose brightness has changed by more than a predetermined threshold and the time at which the change was detected as the measurement result to the measurement signal processing unit.

5. The state detection device according to any one of claims 1 to 4, characterized in that the measurement signal processing unit calculates the period during which the brightness of the light changes.

6. The state detection device according to claim 4, characterized in that the measurement signal processing unit calculates the period of change in brightness at each light-receiving element based on the time at which the brightness of the dataset changes, and includes a display unit that displays the period of change in brightness.

7. The state detection device according to claim 5, wherein the object to be measured is a workpiece or tool installed on a machine tool having a spindle and a feed axis, and the measurement signal processing unit narrows down the signal to be processed from the measurement signal input as the measurement result to a target signal that includes at least one frequency component from the frequency component of the rotational speed of the spindle and the frequency component of an integer multiple of the rotational speed of the spindle, and calculates the period by performing a discrete Fourier transform on the target signal.

8. The state detection device according to any one of claims 1 to 7, characterized in that a sheet containing the stress-emitting element is adhered to the surface of the object to be measured.

9. A control device for controlling a machine tool, comprising: a measuring unit that measures the brightness of light emitted by a stress-emitting element contained on the surface of a workpiece or tool of the machine tool in response to stress generated on the surface of the workpiece; and a measurement signal processing unit that detects changes in the brightness of the light over time based on the measurement result of the measuring unit.

10. A state detection method characterized by comprising: a measurement step of measuring the brightness of light emitted by a stress-emitting element contained in the surface of an object to be measured in response to stress generated on the surface of the object to be measured; and a state detection step of detecting the change in the brightness of the light over time based on the measurement result of the measurement step.

11. The state detection method according to claim 10, characterized in that the measurement step involves measuring the brightness of light using an image sensor in which a plurality of light-receiving elements are arranged in two dimensions and the brightness of the light received by each light-receiving element is output as a measurement result.

12. The state detection method according to claim 10, characterized in that, in the measurement step, an image sensor is used in which a plurality of light-receiving elements are arranged in two dimensions and the brightness of the light received by each light-receiving element is converted into a numerical value and output, and a dataset including the position of the light-receiving element whose brightness has changed by more than a predetermined threshold and the time at which the change was detected is output as the measurement result.

13. The state detection method according to claim 10, characterized in that the period of change in the brightness of the light is calculated in the state detection step.

14. The state detection method according to claim 12, characterized in that the state detection step includes a display step of calculating the period of change in brightness at each photodetector based on the time at which the brightness of the dataset changed, and displaying the period of change in brightness.

15. A state detection method according to any one of claims 10 to 14, characterized in that, before the measurement step, it includes: a preparation step of attaching the stress light emitter to the surface of the object to be measured; and an excitation light irradiation step of irradiating the object to be measured with excitation light containing light of a wavelength that excites the stress light emitter.

16. A control method for controlling a machine tool, comprising: a measurement step of measuring the brightness of light emitted by a stress-emitting element contained on the surface of a workpiece or tool of the machine tool in response to stress generated on the surface of the workpiece; and a state detection step of detecting a change in the brightness of the light over time based on the measurement result of the measurement step.

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