JP5887784B2 - Phase change detecting device, temperature measuring method and measuring temperature calibration method for measuring object having molten liquid part - Google Patents

Description

  The present invention relates to a phase change detection device, a temperature measurement method, and a measurement temperature calibration method for detecting a state of phase change of a substance from a liquid to a solid by image analysis.

  As a case where temperature measurement of a substance accompanied by a phase change is necessary, for example, there is welding. In welding, the cooling rate after welding, the heat affected zone, etc. affect the welding quality, and temperature measurement under various welding conditions is necessary. .

  There is a two-color temperature measuring method as a method for measuring the temperature when measuring the temperature of a substance accompanied by a phase change. In the two-color temperature measurement method, images of the same point are acquired using two lights having different wavelengths, and the temperature is measured from the light intensity and the emissivity of the measurement object. In addition to the temperature, the emissivity varies depending on the state of the object to be measured, solid, liquid, or surface state (such as the presence or absence of a surface oxide film). In the two-color temperature measurement method, the temperature can be obtained as a function of light intensity and emissivity for each pixel at two wavelengths. At this time, if the two wavelengths are close, the wavelength dependence of the emissivity is so small that it can be ignored. Therefore, the temperature of the object to be measured is measured based on the ratio of the light intensity.

  In order to convert the temperature measured by the two-color temperature measurement method into the actual temperature, a reference value is required. Conventionally, a thermocouple or the like is attached to the object to be measured, and the actual temperature (hereinafter referred to as the true temperature). ) Was measured and used as a reference value. For this reason, it took time and effort to prepare for and measure the true temperature.

  In Patent Document 1, a video signal from a television camera and a temperature signal from a radiation thermometer are input to an image processing computer, and the luminance signal of the television camera is converted into a temperature using the temperature signal of the radiation thermometer. A configuration for calculating the temperature of coke is disclosed.

Japanese Patent Laid-Open No. 9-256010

  In view of such circumstances, the present invention is intended to detect a phase change of an object to be measured, or to use the detection of the phase change to measure a true temperature, or to calibrate a measured temperature. .

  The present invention includes a camera capable of capturing an image of a measurement object having a melt portion and outputting image data, and a control arithmetic device. The camera includes an image sensor that is an aggregate of pixels, and the image The data is constituted by the output of the pixel, and the control arithmetic device relates to a phase change detection device that detects a boundary between a liquid phase part and a solid phase part based on the image data.

  Further, the present invention relates to a phase change detection device in which the control arithmetic device has melting point temperature data of a measurement object and measures the boundary temperature based on the melting point temperature data.

  In the present invention, the control arithmetic unit sets a light intensity detection line that crosses the melt portion on the image, creates a light intensity curve based on the output from the pixel along the light intensity detection line, The present invention relates to a phase change detection device that determines a position indicating a light intensity minimum value obtained from the light intensity curve as a boundary between a liquid phase part and a solid phase part.

  Further, the present invention relates to the phase change detection device in which the control arithmetic device sets a plurality of light intensity detection lines crossing the melt portion on the image and obtains a boundary line between the liquid phase portion and the solid phase portion. .

  According to the present invention, the control arithmetic unit detects a change amount for pixels of the entire image and obtains a distribution of the change amount in the entire image, thereby determining a vibrating part and a stationary part. The present invention relates to a phase change detection device that determines a boundary between a vibrating part and a stationary part as a boundary between a liquid phase part and a solid phase part.

  Further, according to the present invention, the control arithmetic device obtains a boundary between the liquid phase part and the solid phase part from a plurality of images in time series, and calculates a solidification rate of the melt part based on a change with time of the boundary. This relates to a change detection device.

  The present invention also includes a step of imaging the welded portion with a camera capable of outputting image data, a step of detecting a boundary between the liquid phase portion and the solid phase portion in the image based on the image data output by the camera, And a step of identifying the boundary temperature based on the melting point temperature of the material.

  In the two-color temperature measurement method, the present invention also includes a step of imaging the welded portion with a camera capable of outputting image data, and a liquid phase portion and a solid phase portion in the image based on the image data output from the camera. A reference temperature is measured based on a temperature measurement method including a step of detecting a boundary of the substrate and a step of specifying the temperature of the boundary based on a melting point temperature of the base material, and obtained by a two-color temperature measurement method based on the reference temperature The present invention relates to a measurement temperature calibration method for calibrating the measured temperature results.

  According to the present invention, it comprises a camera capable of imaging a measurement object having a melt portion and outputting image data, and a control arithmetic device, the camera having an image sensor that is an aggregate of pixels, The image data is constituted by the output of the pixel, and the control arithmetic unit detects the boundary between the liquid phase part and the solid phase part based on the image data, so that the phase change of the melt part can be detected, and the phase change The true temperature of the boundary can be measured based on the melting point temperature of the measurement object even when the boundary is detected.

  According to the invention, the step of imaging the welded portion with a camera capable of outputting image data, the step of detecting the boundary between the liquid phase portion and the solid phase portion in the image based on the image data output by the camera, And a step of specifying the temperature of the boundary based on the melting point temperature of the base material, so that the true temperature of the boundary between the liquid phase portion and the solid phase portion of the welded portion can be measured without providing a temperature sensor.

  According to the present invention, in the two-color temperature measurement method, the process of imaging the welded portion with a camera capable of outputting image data, and the liquid phase portion in the image based on the image data output from the camera are fixed. A reference temperature is measured based on a temperature measurement method having a step of detecting a boundary of a phase part and a step of specifying a temperature of the boundary based on a melting point temperature of a base material, and a two-color temperature measurement method based on the reference temperature Since the obtained temperature measurement result is calibrated, the temperature measurement result obtained by the two-color temperature measurement method can be calibrated without providing a temperature sensor.

It is a schematic block diagram of the 1st Example which concerns on this invention. (A) is a figure which shows the image acquired in the 1st Example, (B) shows the light intensity curve obtained from this image.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an embodiment according to the present invention. In FIG. 1, reference numeral 1 denotes a phase change detection apparatus according to this embodiment, and reference numeral 2 denotes a measurement object.

  FIG. 1 schematically shows a case where welding is being performed, where the measurement object 2 is a base material to be welded, and 3 is a molten pool when welding is being performed. In FIG. 1, the welding apparatus is omitted.

  In FIG. 1, reference numeral 11 denotes a camera, which includes an image sensor 12 that is an aggregate of a large number of pixels, such as a CCD and a CMOS sensor, and outputs digital image signals of still images and continuous images. Further, a reference position in the image sensor 12, for example, the center of the image sensor 12 and the optical axis of the camera 11 coincide with each other, and the position of each pixel is specified with respect to the reference position. . Reference numeral 13 denotes a control arithmetic unit that executes various processes and calculations based on the image signal from the image sensor 12 to execute phase change, temperature measurement, calibration of measured temperature, measurement of cooling rate, and the like. Reference numeral 14 denotes a display device, which displays an image captured by the camera 11, a calculation result of the control calculation device 13, and the like.

  The control arithmetic unit 13 includes an arithmetic processing unit (CPU) 15, a storage unit 16, an image processing unit 17, and an operation unit 18. The storage unit 16 has an image processing program for performing image processing, Based on the calculated light intensity, an image processing program for calculating the light intensity or temporal deviation for each pixel from the image signal from the image sensor 12 and associating the calculated result with the position information of the pixel in the image sensor 12 A calculation program for calculating a light intensity curve and calculating a dynamic change of the surface of the measurement object 2 based on the deviation, and a boundary between the liquid phase and the solid phase based on the obtained light intensity curve or the dynamic change of the surface. A program such as a desired program is stored. The storage unit 16 stores data necessary for executing the program, for example, the temperature of the melting point of the measurement object 2.

  In the present embodiment, the camera 11 images the molten pool 3 and the surrounding area including the molten pool 3, and measures a region where a phase change occurs based on image data obtained by imaging.

  The first embodiment will be described below.

  The emissivity due to the temperature of the substance differs between solid and liquid, and when the liquid solidifies, the light intensity increases despite the temperature decreasing. Therefore, if a point where the light intensity is increased at a part where the temperature is reduced is detected on the image, it can be detected that the part is causing the phase change.

  The camera 11 captures still images at predetermined time intervals, or continuous images, and the captured images are input to the arithmetic processing unit 15 via the image processing unit 17 or the arithmetic processing unit. 15 and stored in the storage unit 16.

  FIG. 2A shows an image 19 of the measurement object 2 imaged by the camera 11 and is called from the storage unit 16 for image processing. In FIG. 2A, 21 indicates a base material (that is, a solid portion), and 22 indicates a molten pool (that is, a liquid portion). The arithmetic processing unit 15 performs the following processing using a program stored in the storage unit 16.

  On the image 19, a light intensity detection line A-A 'traversing the pool 22 is set, and an output signal of a pixel in the light intensity detection line A-A' is extracted from the image data. Further, a light intensity curve along the light intensity detection line A-A ′ is created from the output signal of the pixel and the address of the pixel.

  Since the obtained light intensity curve crosses the boundary between the liquid phase and the solid phase, the light intensity increases at the site where the solid phase is formed. In the liquid phase part and the solid phase part, the light intensity decreases corresponding to the decrease in temperature.

  FIG. 2 (B) shows a light intensity curve 23. The range of X is the light intensity on the surface of the pool 22, corresponding to the temperature of the liquid, and the center (point O) has the maximum light intensity. Yes, the temperature decreases toward the periphery, and the light intensity also decreases.

  Further, on the light intensity curve 23, the light intensity is inverted from decrease to increase at the point P, but the temperature does not increase toward the periphery, so it is determined that the emissivity on the surface has changed. it can.

  That is, the point P indicates that the phase is changed from the liquid phase to the solid phase. In other words, the point P at which the phase changes from the liquid phase to the solid phase indicates the minimum value of the light intensity.

  The range of Y is the range where the liquid phase changes to the solid phase, and the light intensity increases even though the temperature does not change. Furthermore, although it becomes the 2nd maximum value at the point Q, it is thought that it changed into the solid phase completely. Beyond the point Q (Z range), it becomes completely solid, so the emissivity corresponds to the temperature, and the light intensity decreases with decreasing temperature.

  Thus, the light intensity detection line A-A ′ crossing the pool 22, that is, the liquid part is set, a light intensity curve along the light intensity detection line A-A ′ is obtained, and the light intensity detection line is obtained. If the minimum point P of the light intensity at A-A ′ is obtained, it can be measured that the point P is a change point from the liquid phase to the solid phase.

  Next, since the melting point temperature (temperature at which the phase changes from liquid to solid) is specific to the substance, if the melting point temperature of the measuring object 2 is measured in advance and stored in the storage unit 16, It can be immediately measured that the temperature at the point P is the melting point temperature.

  The obtained temperature at the point P can be used for calibration of the measured temperature obtained by the temperature measurement.

  For example, it can be used as a reference value for converting the temperature measured by the two-color temperature measurement method into an actual temperature.

  Next, the light intensity curve 23 is calculated for each frame of the continuous image or for each still image acquired at a predetermined time interval, and the change in the position of the point P is observed in time series, or By dividing the amount of change of the position of the point P with time by time, the moving speed of the freezing point, that is, the solidifying speed can be measured. The time interval of the still image is set to a time interval that can follow a change in the state of the measurement object 2, for example, a solidification speed or a welding speed.

  Furthermore, by setting the light intensity detection line A-A ′ at intervals of, for example, 30 ° instead of one, the solidification point along the contour of the pool 22 can be detected, and the movement speed in two dimensions as a solidification line can be detected. It can be measured.

  It is known that when the molten metal solidifies, the solidification rate has an effect on the properties and mechanical performance of the metal, and the optimum welding conditions are determined by measuring the solidification rate of the molten pool 3 during welding. Can be set.

  In the above embodiment, the image is temporarily stored in the storage unit 16 and read from the storage unit 16 as appropriate, and the image processing is performed. However, the image processing unit 17 immediately processes the image acquired by the camera 11. The light intensity curve 23 may be obtained and the freezing point or the freezing line may be measured in real time.

  Furthermore, in the above embodiment, the freezing point is measured based on the light intensity of the surface of the measuring object 2, but as a second embodiment, the vibration when the liquid part solidifies is detected and the freezing point or the freezing line is set. Can be detected.

  In particular, in a welding method for supplying filler metal such as MIG welding, the vibration of the surface of the molten pool 3 is significant, and the vibration of the surface is detected from the image.

  The configuration in the second embodiment is the same as that of the first embodiment shown in FIG. The following will be described with reference to FIG.

  If the image data obtained from the camera 11 is a moving image, for each frame image, if it is a still image, the amount of change is detected for all pixels, and the distribution of the amount of change in the entire image is obtained. Thus, the boundary between the vibrating part and the stationary part can be obtained. Note that brightness and luminance are obtained as changes obtained for one pixel.

  Alternatively, a threshold value may be set in advance, and a boundary between the stationary state and the vibration may be obtained by determining that the displacement is smaller than the threshold value and stationary, and that the displacement larger than the threshold value is vibration. Alternatively, the presence / absence of vibration may be detected by determining the amount of change for each unit, not for each pixel but for each predetermined number of pixels, for example, 10 × 10 pixels as a unit.

  As described above, in the present invention, it is possible to detect a freezing point and a solidification line when changing from a liquid phase to a solid phase and further measure a solidification rate. However, the solidification rate may be controlled based on the measured solidification rate. .

  For example, when hot water is poured into a mold and solidified, a part that solidifies faster and a part that solidifies later occur depending on the shape of the mold. If a portion having a high solidification rate is mixed with a portion having a low solidification rate, non-uniform quality may occur. For example, by using the first embodiment, the solidification line is detected and the solidification rate is measured. The portion can be heated, and the solidification rate can be made uniform by delaying the solidification rate.

  In addition, the present invention converts the temperature measured by the two-color temperature measurement method into the actual temperature, a method for measuring the true temperature as a reference value, and the temperature measured by the two-color temperature measurement method as the actual temperature. It can be implemented as a calibration method.

  In the two-color temperature measurement method, two types of images are acquired for the measurement object 2 with light beams having different wavelengths. Based on one of the acquired images, the present invention is implemented to determine the boundary between the liquid phase and the solid phase. It is possible to detect and identify the boundary temperature based on the melting point temperature of the measurement object 2, and calibrate the temperature obtained by the two-color temperature measurement method using the identified temperature as a reference temperature.

  When the present invention is applied to the two-color temperature measuring method, the reference temperature can be easily measured without separately providing a temperature detector for measuring the reference temperature, and the apparatus cost can be reduced and the measurement work can be simplified.

  For each image obtained at two wavelengths by the two-color temperature measurement method, the boundary between the liquid phase and the solid phase is detected, and the obtained two detection results are averaged to improve the measurement accuracy. Also good.

DESCRIPTION OF SYMBOLS 1 Phase change detection apparatus 2 Measurement object 3 Molten pool 11 Camera 12 Image sensor 13 Control arithmetic device 14 Display apparatus 15 Arithmetic processing part 16 Storage part 17 Image processing part 18 Operation part 19 Image 21 Base material 22 Pool 23 Light intensity curve

Claims (7)

An imaging device comprising: a camera capable of imaging a measurement object having a melt portion and outputting image data; and a control arithmetic device having melting point temperature data of the measurement object , wherein the camera is an aggregate of pixels. And the image data is constituted by the output of the pixel, and the control arithmetic unit sets a light intensity detection line across the melt portion on the image based on the image data, and the light intensity detection line A light intensity curve is created based on the output from the pixels along, and the position indicating the light intensity minimum value obtained by the light intensity curve is determined as the boundary between the liquid phase part and the solid phase part, and based on the melting point temperature data A phase change detection device for measuring a temperature of the boundary . The phase change detection device according to claim 1, wherein the control arithmetic device sets a plurality of light intensity detection lines crossing the melt portion on the image to obtain a boundary line between the liquid phase portion and the solid phase portion. An imaging device comprising: a camera capable of imaging a measurement object having a melt portion and outputting image data; and a control arithmetic device having melting point temperature data of the measurement object , wherein the camera is an aggregate of pixels. The image data is constituted by the output of the pixel, and the control arithmetic unit detects a change amount for the pixel of the entire image based on the image data, and obtains a distribution of the change amount in the entire image. Determining the vibrating part and the stationary part, determining the boundary between the vibrating part and the stationary part as the boundary between the liquid phase part and the solid phase part, and based on the melting point temperature data A phase change detection device for measuring a temperature of the boundary . The control arithmetic unit, when each seeking the boundaries of the liquid phase and the solid phase portion of a plurality of images in sequence, claims 1 to calculating the solidification rate of the melt portion based on the temporal change of the boundary 4. The phase change detection device according to any one of 3 ). The step of imaging the welded portion with a camera capable of outputting image data, and setting a light intensity detection line that crosses the melted portion on the image based on the image data output by the camera , along the light intensity detection line was created on the basis of light intensity curve of an output from a pixel, the position of an optical intensity minimum value obtained by the optical intensity curve is determined that the boundary between liquid phase and solid phase portion, and the liquid phase portion in the image temperature measurement method comprising: the step of detecting the boundary of the solid phase portion, and a step of identifying the temperature of the boundary on the basis of the melting point temperature of the base material. By imaging the welded portion with a camera capable of outputting image data, and detecting the amount of change for the pixels of the entire image based on the image data output by the camera , and obtaining the distribution of the amount of change over the entire image, determining a portion which is stationary with sites oscillating, the boundaries of the site which is stationary with sites oscillating determines the boundary of the liquid phase and the solid phase portion, the liquid phase portion of the image wherein the step of detecting the boundary of the solid phase portion, the temperature measuring method characterized by a step of identifying the temperature of the boundary on the basis of the melting point temperature of the base material and. In the two-color temperature measurement method, the reference temperature is measured based on the temperature measurement method of claim 5 or claim 6 , and the temperature measurement result obtained by the two-color temperature measurement method is calibrated based on the reference temperature. A characteristic measuring temperature calibration method.

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