A method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions

Abstract

The present invention relates to a method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions, and belongs to the field of amplitude measurement technology. A sample to be measured is placed in an electromagnetic suspension device, and the sample to be measured is heated and suspended by controlling the electromagnetic suspension conditions to obtain a suspended droplet, and a high-speed camera of the electromagnetic suspension device is used to obtain a plurality of continuous oscillation pictures; the plurality of continuous oscillation pictures obtained are processed by computer programs to realize object positioning, contour marking, threshold segmentation, sampling denoising and other links; the processed information is recorded and counted by programming to realize the change of the oscillation position of the suspended droplet within n oscillation cycles, and then the maximum amplitude and the average amplitude of the oscillation of a certain metal alloy sample under suspension conditions are calculated. The present invention can obtain accurate, fast and reliable amplitude data under suspension oscillation conditions for different types of metal alloys.

Description

Technical Field

[0001] The invention relates to a method for measuring the amplitude of a metal molten droplet under electromagnetic suspension conditions, and belongs to the technical field of amplitude measurement. Background Art

[0002] The amplitude of liquid metal under electromagnetic suspension conditions directly affects the suspension stability of the molten droplet, and the amplitude is closely related to the alloy composition and thermodynamic properties such as metal alloy viscosity and surface tension. Measuring the amplitude of liquid metal droplets is conducive to exploring the stable suspension conditions of the droplet and improving the measurement accuracy of its thermodynamic parameters.

[0003] At present, the commonly used amplitude displacement measurement mainly includes contact type and non-contact type. The non-contact type is represented by the traditional laser double-beam interferometer, Doppler vibrometer, laser self-mixing interferometer, ultrasonic ranging, and high-speed photography. The contact type includes rope displacement sensors that directly measure vibration displacement, and acceleration sensors that measure acceleration and then integrate to obtain the vibration displacement trend. However, since the metal droplet is in the quartz tube during the suspension process, and the high-temperature metal droplet cannot directly contact the detection instrument, the non-contact type is more suitable for measuring the amplitude of the metal droplet. According to literature survey, there is no patent report on the measurement of the amplitude of molten metal droplets under electromagnetic suspension conditions. The existing patents on molten metal droplets under electromagnetic suspension conditions include: "Space rapid solidification ground simulation method and experimental device, patent number: CN1158916A", "A method for regulating the morphology of electromagnetically suspended liquid metal, patent number: CN108183632B", "An electromagnetic suspension ball system with acceleration detection function and its control method, patent number: CN110320385A", "Method for rapid solidification of metal droplets, patent number: CN111230130A", "A method for measuring the oscillation frequency of metal droplets under electromagnetic suspension conditions, patent number: CN113432700A", etc.

[0004] Metal droplets oscillate during the electromagnetic suspension refining process. Since this phenomenon has a great influence on the suspension stability of the metal droplets and the measurement results of some thermodynamic properties, it is necessary to design a method that can detect the amplitude of the suspended droplets, which is conducive to exploring the stable suspension conditions of the droplets and improving the accuracy and reliability of the measurement results of some thermodynamic properties. Summary of the invention

[0005] In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions. The metal sample of the present invention is rapidly suspended and melted under electromagnetic suspension conditions, and the non-contact suspension conditions avoid the interference of the container wall on the amplitude measurement, and the amplitude of a high-melting-point metal droplet can be measured under high-temperature oscillation conditions. The present invention is implemented by the following technical solutions.

[0006] The present invention uses electromagnetic suspension containerless technology and a high-speed camera to measure the amplitude of metal droplets, designs a new method for measuring the amplitude of suspended metal droplets, and realizes the measurement of the droplet amplitude under electromagnetic suspension conditions of high-melting-point metal alloy materials. In order to avoid the shortcomings of the prior art, the present invention proposes a method for measuring the amplitude of electromagnetically suspended liquid metal, which is suspended, heated and melted by a specially designed electromagnetic suspension coil, and then the amplitude of the droplet on the surface is measured through image acquisition and data processing and analysis.

[0007] A method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions, the specific steps of which include:

[0008] Step 1, place the sample to be measured in an electromagnetic suspension device, suspend the sample to be measured by controlling the electromagnetic suspension conditions to obtain a suspended molten droplet 2, and use the high-speed camera 6 of the electromagnetic suspension device to obtain multiple continuous oscillation pictures; the suspension coil 3 in the electromagnetic suspension device is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten droplet 2, and the high-speed camera 6 takes pictures of the suspended molten droplet, and the infrared thermometer 4 and the high-speed camera 6 are both connected to the computer system 5 for data recording and processing.

[0009] Specifically:

[0010] Step 1.1, place the sample to be measured in the suspension coil 3, adjust the infrared thermometer 4 so that its focus is aligned with the sample position, adjust the focal length of the high-speed camera 6 so that it can clearly shoot the sample, turn on the gas treatment system 1 to spray the sample for 3-5 minutes to provide a protective atmosphere;

[0011] Step 1.2, turn on the power control system 7, the sample is suspended at the center of the suspension coil 3 under the action of the high-frequency alternating magnetic field and gradually heated up, the output power of the power control system 7 is increased until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the sample can be observed to change from an irregular shape to an ellipsoid through the high-speed camera 6, thereby obtaining a suspended molten drop 2;

[0012] Step 2, actively storing the continuous multiple oscillation pictures obtained in step 1 into a file specified by the computer, and then using the computer MATLAB software to program the oscillation pictures, specifically: the program reads the picture information from the corresponding file, locates the object (droplet) in the image, generates a thumbnail by downsampling and marks and displays the outline of the object, performs threshold segmentation according to the different gray levels occupied by the target image and the background, performs denoising on the image to remove image interference, extracts the connected components of the binary image, and determines and displays the processed image information;

[0013] Step 3, the continuous oscillation images processed in step 2 are counted and recorded to obtain an oscillation position change diagram by oscillating the oscillation positions of the suspended droplet 2 in n oscillation cycles. The oscillation peak at the top and the trough at the bottom of the oscillation position change diagram are marked with triangles. The amplitude value of this oscillation is the adjacent peak minus the trough, which is calculated by formula (1), and the maximum amplitude is obtained by formula (2) and the average amplitude is obtained by formula (3):

[0014] A i =A i∧ -A i∨ (1);

[0015] A max =max(A i ) (2);

[0016]

[0017] Among them A i is the amplitude of the ith period of the suspended droplet 2, A i∧ is the peak value of the oscillation wave of the ith period of the suspended droplet 2, A i∨ A is the oscillation trough value of the i-th cycle of the suspended droplet 2; max is the maximum amplitude; A ave is the average amplitude of the suspended molten droplet, unit: pixel; n is the number of oscillation cycles of the suspended molten droplet.

[0018] The sample to be measured in step 1 is a conductor or a semiconductor, and its melting point temperature may be 800-3000K. The mass of the prepared granular sample is 0.5-3g.

[0019] The delay of the high-speed camera 6 is set to 5-30ms, the exposure is 50ns-40ms, and the lens aperture is 1.5F.

[0020] In the above step 1.1, the protective gas introduced into the gas treatment system 1 is argon, helium or a protective gas mixed in any volume of the two, and the gas flow rate can be 0.1L / min-5.0L / min.

[0021] In the above step 1.2, the high-frequency current output by the power control system 7 is 200-600A, the current frequency is 200kHz-400kHz, and the power is 1-15kW.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention provides a method for measuring the amplitude of a high-temperature liquid metal alloy under electromagnetic suspension, which can obtain accurate, fast and reliable amplitude data under suspension oscillation conditions for different types of metal alloys.

[0024] 2. The present invention uses electromagnetic suspension containerless technology, high-speed camera image acquisition and computer data processing to simultaneously collect the amplitude measurement of high-temperature metal droplets in the up and down directions and left and right directions of suspended droplets, and can realize online measurement of the amplitude of suspended droplets in two directions.

[0025] 3. The device can not only measure the amplitude of the molten droplet under high temperature conditions, but also has high resolution. The non-contact measurement method makes it unaffected by the container wall, which is conducive to studying the stability of high-temperature molten droplet suspension. At the same time, the device also has the advantages of simple structure and rapid measurement, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the device for measuring the amplitude of high-temperature metal alloy under electromagnetic suspension conditions of the present invention;

[0027] In the figure: 1-gas processing system, 2-suspended molten droplet, 3-suspended coil, 4-infrared thermometer, 5-computer system, 6-high-speed camera, 7-power control system.

[0028] Figure 2 It is a specific test physical picture of Example 1 of the present invention; (a) in the figure is 3 representative pictures obtained after processing the metal droplet suspension picture; (b) is a camera picture with a ruler; (c) is an oscillation waveform picture in the left and right and up and down directions.

[0029] Figure 3 It is a specific test physical picture of Example 2 of the present invention; (a) in the figure is 3 representative pictures obtained after processing the metal droplet suspension picture; (b) is a camera picture with a ruler; (c) is an oscillation waveform picture in the left and right and up and down directions.

[0030] Figure 4 It is a specific test physical picture of Example 3 of the present invention; (a) in the figure is 3 representative pictures obtained after processing the metal droplet suspension picture; (b) is a camera picture with a ruler; (c) is an oscillation waveform picture in the left and right and up and down directions. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0032] Example 1

[0033] like Figure 1 As shown, the method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions comprises the following specific steps:

[0034] Step 1, place the sample to be measured in an electromagnetic suspension device, suspend the sample to be measured by controlling the electromagnetic suspension conditions to obtain a suspended molten droplet 2, and use the high-speed camera 6 of the electromagnetic suspension device to obtain multiple continuous oscillation pictures; the suspension coil 3 in the electromagnetic suspension device is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten droplet 2, and the high-speed camera 6 takes pictures of the suspended molten droplet, and the infrared thermometer 4 and the high-speed camera 6 are both connected to the computer system 5 for data recording and processing.

[0035] Specifically:

[0036] Step 1.1, place the sample to be measured (titanium aluminum alloy particles, 1.8 g) in the suspension coil 3, adjust the infrared thermometer 4 so that its focus is aligned with the sample position, adjust the focal length of the high-speed camera 6 so that it can clearly shoot the sample, turn on the gas treatment system 1 to spray the sample for 5 minutes to provide a protective atmosphere (the gas atmosphere is 30% argon and 70% He, and the gas flow rate is 1.5 L / min);

[0037] Step 1.2, cooling water is passed into the suspension coil 3, and the power control system 7 is turned on (current is 374A, power frequency is 297kHz, power is 5.6kW). The sample is suspended at the center of the suspension coil 3 under the action of the high-frequency alternating magnetic field and gradually heated up. The output power of the power control system 7 is increased until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the sample can be observed to change from an irregular shape to an ellipsoid through the high-speed camera 6, thereby obtaining a suspended molten drop 2;

[0038] Step 2: Actively store the continuous multiple oscillation images obtained in step 1 into a file specified by the computer, and then use the computer MATLAB software to program the oscillation images. Specifically, the program reads the image information from the corresponding file, locates the object (droplet) in the image, generates a thumbnail by downsampling, marks and displays the outline of the object, performs threshold segmentation according to the different gray levels occupied by the target image and the background, performs denoising on the image to remove image interference, extracts the connected components of the binary image, determines and displays the processed image information, and obtains several representative images after image processing. Figure 2 (a)

[0039] Step 3, the continuous oscillation images processed in step 2 are counted and recorded to obtain an oscillation position change diagram by oscillating the oscillation positions of the suspended droplet 2 in n oscillation cycles. The oscillation peak at the top and the trough at the bottom of the oscillation position change diagram are marked with triangles. The amplitude value of this oscillation is the adjacent peak minus the trough, which is calculated by formula (1), and the maximum amplitude is obtained by formula (2) and the average amplitude is obtained by formula (3):

[0040] Ai =A i∧ -A i∨ (1);

[0041] A max =max(A i ) (2);

[0042]

[0043] Among them A i is the amplitude of the ith period of the suspended droplet 2, A i∧ is the peak value of the oscillation wave of the ith period of the suspended droplet 2, A i∨ A is the oscillation trough value of the i-th cycle of the suspended droplet 2; max is the maximum amplitude; A ave is the average amplitude of the suspended molten droplet, unit: pixel; n is the number of oscillation cycles of the suspended molten droplet.

[0044] In this embodiment, the camera image with a ruler is as follows Figure 2 As shown in (b), its resolution is 1920*1080 pixels. The pixel difference corresponding to 1cm on the ruler is 493-291=202 pixels. It can be calculated that each pixel is 0.050mm. Figure 2 As shown in (c), the amplitude values ​​in the left-right direction (i.e., X direction) and the amplitude values ​​in the up-down direction (i.e., Y direction) are calculated according to formula (1). According to formulas (2) and (3), it can be obtained that when the titanium-aluminum alloy suspended droplet is at 1950°C, the maximum amplitude of the left-right oscillation is 33.03 pixels, i.e., 1.65 mm, and the average amplitude is 9.75 pixels, i.e., 0.49 mm. The maximum amplitude of the up-down oscillation is 9.32 pixels, i.e., 0.47 mm, and the average amplitude is 3.78 pixels, i.e., 0.19 mm.

[0045] Example 2

[0046] like Figure 1 As shown, the method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions comprises the following specific steps:

[0047] Step 1, place the sample to be measured in an electromagnetic suspension device, suspend the sample to be measured by controlling the electromagnetic suspension conditions to obtain a suspended molten droplet 2, and use the high-speed camera 6 of the electromagnetic suspension device to obtain multiple continuous oscillation pictures; the suspension coil 3 in the electromagnetic suspension device is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten droplet 2, and the high-speed camera 6 takes pictures of the suspended molten droplet, and the infrared thermometer 4 and the high-speed camera 6 are both connected to the computer system 5 for data recording and processing.

[0048] Specifically:

[0049] Step 1.1, place the sample to be measured (ferrosilicon alloy particles, 1.3 g) in the suspension coil 3, adjust the infrared thermometer 4 so that its focus is aligned with the sample position, adjust the focal length of the high-speed camera 6 so that it can clearly shoot the sample, turn on the gas treatment system 1 to spray the sample for 5 minutes to provide a protective atmosphere (the gas atmosphere is 30% argon and 70% He, and the gas flow rate is 1.5 L / min);

[0050] Step 1.2, cooling water is passed into the suspension coil 3, and the power control system 7 is turned on (current is 374A, power frequency is 297kHz, power is 5.6kW). The sample is suspended at the center of the suspension coil 3 under the action of the high-frequency alternating magnetic field and gradually heated up. The output power of the power control system 7 is increased until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the sample can be observed to change from an irregular shape to an ellipsoid through the high-speed camera 6, thereby obtaining a suspended molten drop 2;

[0051] Step 2: Actively store the continuous multiple oscillation images obtained in step 1 into a file specified by the computer, and then use the computer MATLAB software to program the oscillation images. Specifically, the program reads the image information from the corresponding file, locates the object (droplet) in the image, generates a thumbnail by downsampling, marks and displays the outline of the object, performs threshold segmentation according to the different gray levels occupied by the target image and the background, performs denoising on the image to remove image interference, extracts the connected components of the binary image, determines and displays the processed image information, and obtains several representative images after image processing. Figure 3 (a)

[0052] Step 3, the continuous oscillation images processed in step 2 are counted and recorded to obtain an oscillation position change diagram by oscillating the oscillation positions of the suspended droplet 2 in n oscillation cycles. The oscillation peak at the top and the trough at the bottom of the oscillation position change diagram are marked with triangles. The amplitude value of this oscillation is the adjacent peak minus the trough, which is calculated by formula (1), and the maximum amplitude is obtained by formula (2) and the average amplitude is obtained by formula (3):

[0053] A i =A i∧ -A i∨ (1);

[0054] A max =max(A i ) (2);

[0055]

[0056] Among them A i is the amplitude of the ith period of the suspended droplet 2, A i∧is the peak value of the oscillation wave of the ith period of the suspended droplet 2, A i∨ A is the oscillation trough value of the i-th cycle of the suspended droplet 2; max is the maximum amplitude; A ave is the average amplitude of the suspended molten droplet, unit: pixel; n is the number of oscillation cycles of the suspended molten droplet.

[0057] In this embodiment, the camera image with a ruler is as follows Figure 3 As shown in (b), its resolution is 1920*1080 pixels. The pixel difference corresponding to 1cm on the ruler is 423-299=224 pixels. It can be calculated that each pixel is 0.045mm. Figure 3 As shown in (c), the amplitude values ​​in the left-right direction (i.e., X direction) and the amplitude values ​​in the up-down direction (i.e., Y direction) are calculated according to formula (1). According to formulas (2) and (3), it can be obtained that when the ferrosilicon alloy suspended droplet is at 1900°C, the maximum amplitude of the left-right oscillation is 22.65 pixels, i.e., 1.02 mm, and the average amplitude is 4.35 pixels, i.e., 0.196 mm; the maximum amplitude of the up-down oscillation is 4.47 pixels, i.e., 0.20 mm, and the average amplitude is 1.38 pixels, i.e., 0.06 mm.

[0058] Example 3

[0059] like Figure 1 As shown, the method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions comprises the following specific steps:

[0060] Step 1, place the sample to be measured in an electromagnetic suspension device, suspend the sample to be measured by controlling the electromagnetic suspension conditions to obtain a suspended molten droplet 2, and use the high-speed camera 6 of the electromagnetic suspension device to obtain multiple continuous oscillation pictures; the suspension coil 3 in the electromagnetic suspension device is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten droplet 2, and the high-speed camera 6 takes pictures of the suspended molten droplet, and the infrared thermometer 4 and the high-speed camera 6 are both connected to the computer system 5 for data recording and processing.

[0061] Specifically:

[0062] Step 1.1, place the sample to be measured (pure iron particles, 1.9 g) in the suspension coil 3, adjust the infrared thermometer 4 so that its focus is aligned with the sample position, adjust the focal length of the high-speed camera 6 so that it can clearly shoot the sample, turn on the gas treatment system 1 to spray the sample for 5 minutes to provide a protective atmosphere (the gas atmosphere is 30% argon and 70% He, and the gas flow rate is 1.5 L / min);

[0063] Step 1.2, cooling water is passed into the suspension coil 3, and the power control system 7 is turned on (current is 374A, power frequency is 297kHz, power is 5.6kW). The sample is suspended at the center of the suspension coil 3 under the action of the high-frequency alternating magnetic field and gradually heated up. The output power of the power control system 7 is increased until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the sample can be observed to change from an irregular shape to an ellipsoid through the high-speed camera 6, thereby obtaining a suspended molten drop 2;

[0064] Step 2: Actively store the continuous multiple oscillation images obtained in step 1 into a file specified by the computer, and then use the computer MATLAB software to program the oscillation images. Specifically, the program reads the image information from the corresponding file, locates the object (droplet) in the image, generates a thumbnail by downsampling, marks and displays the outline of the object, performs threshold segmentation according to the different gray levels occupied by the target image and the background, performs denoising on the image to remove image interference, extracts the connected components of the binary image, determines and displays the processed image information, and obtains several representative images after image processing. Figure 4 (a)

[0065] Step 3, the continuous oscillation images processed in step 2 are counted and recorded to obtain an oscillation position change diagram by oscillating the oscillation positions of the suspended droplet 2 in n oscillation cycles. The oscillation peak at the top and the trough at the bottom of the oscillation position change diagram are marked with triangles. The amplitude value of this oscillation is the adjacent peak minus the trough, which is calculated by formula (1), and the maximum amplitude is obtained by formula (2) and the average amplitude is obtained by formula (3):

[0066] A i =A i∧ -A i∨ (1);

[0067] A max =max(A i ) (2);

[0068]

[0069] Among them A i is the amplitude of the ith period of the suspended droplet 2, A i∧ is the peak value of the oscillation wave of the ith period of the suspended droplet 2, A iv A is the oscillation trough value of the i-th cycle of the suspended droplet 2; max is the maximum amplitude; A ave is the average amplitude of the suspended molten droplet, unit: pixel; n is the number of oscillation cycles of the suspended molten droplet.

[0070] In this embodiment, the camera image with a ruler is as follows Figure 4As shown in (b), its resolution is 1920*1080 pixels. The pixel difference corresponding to 1cm on the ruler is 495-378=117 pixels. It can be calculated that each pixel is 0.085mm. Figure 2 As shown in (c), the amplitude values ​​in the left-right direction (i.e., X direction) and the amplitude values ​​in the up-down direction (i.e., Y direction) are calculated according to formula (1). According to formulas (2) and (3), it can be obtained that when the pure iron suspended droplet is at 1850°C, the maximum amplitude of the left-right oscillation is 24.21 pixels, i.e., 2.06 mm, and the average amplitude is 5.80 pixels, i.e., 0.49 mm. The maximum amplitude of the up-down oscillation is 12.18 pixels, i.e., 1.04 mm, and the average amplitude is 2.15 pixels, i.e., 0.18 mm.

[0071] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions, characterized in that The specific steps include: Step 1, placing a sample to be measured in an electromagnetic suspension device, suspending the sample to be measured by controlling electromagnetic suspension conditions to obtain a suspended molten drop (2), and taking a plurality of continuous oscillation images by a high-speed camera (6) of the electromagnetic suspension device; Step 2, programming the continuous multiple oscillation pictures obtained in step 1, specifically: the program reads the picture information from the corresponding file, locates the object in the image, generates a thumbnail by downsampling and marks and displays the outline of the object, performs threshold segmentation according to the different gray levels occupied by the target image and the background, performs denoising on the image to remove image interference, extracts the connected components of the binary image, and determines and displays the processed image information; Step 3, the continuous oscillation images processed in step 2 are counted and recorded to obtain an oscillation position change diagram by recording the oscillation positions of the suspended molten droplet (2) in n oscillation cycles. The oscillation peak at the top and the trough at the bottom of the oscillation position change diagram are marked with triangles. The amplitude value of this oscillation is the adjacent peak minus the trough, which is calculated by formula (1), and the maximum amplitude is obtained by formula (2) and the average amplitude is obtained by formula (3): A i =A i∧ -A i∨ (1); A max =max(A i ) (2); Among them A i is the amplitude of the ith period of the suspended droplet (2), A i∧ is the peak value of the oscillation wave of the suspended droplet (2) in the i-th cycle, A i∨ A is the oscillation trough value of the suspended droplet (2) in the i-th cycle; max is the maximum amplitude; A ave is the average amplitude of the suspended molten droplet; n is the number of oscillation cycles of the suspended molten droplet.

2. The method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions according to claim 1, characterized in that: The sample to be measured in step 1 is a conductor or a semiconductor, and its melting point temperature may be 800-3000K. The mass of the prepared granular sample is 0.5-3g.

3. The method for measuring the amplitude of a metal droplet under electromagnetic suspension conditions according to claim 1, characterized in that: The delay of the high-speed camera (6) is set to 5-30ms, the exposure is 50ns-40ms, and the lens aperture is 1.5F.

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