CN115493685A - A Method for Measuring the Amplitude of Metal Droplets Under the Condition of Electromagnetic Levitation - Google Patents

Abstract

The invention relates to a method for measuring the amplitude of a metal droplet under an electromagnetic suspension condition, and belongs to the technical field of amplitude measurement. Placing a sample to be measured in electromagnetic suspension equipment, heating and suspending the sample to be measured by controlling electromagnetic suspension conditions to obtain suspended molten drops, and shooting by a high-speed camera of the electromagnetic suspension equipment to obtain continuous multiple oscillation pictures; carrying out image processing on continuous multiple oscillation images obtained by shooting through links of object positioning, contour marking, threshold segmentation, sampling denoising and the like realized by a computer program; and recording and counting the oscillation position change condition of the suspended molten drop in n oscillation periods by programming the processed information, and then calculating to obtain the maximum amplitude value and the average amplitude value of the oscillation of a certain metal alloy sample under the suspension condition. The invention can obtain accurate, rapid and reliable amplitude data under the suspension oscillation condition aiming at different types of metal alloys.

Description

A Method for Measuring the Amplitude of Metal Droplets Under the Condition of Electromagnetic Levitation

technical field

The invention relates to a method for measuring the amplitude of metal droplets under the condition of electromagnetic levitation, and belongs to the technical field of amplitude measurement.

Background technique

Under the condition of electromagnetic levitation, the vibration amplitude of liquid metal will directly affect the suspension stability of droplet, and the size of the amplitude is closely related to the alloy composition, and also related to the thermodynamic properties of the metal alloy such as viscosity and surface tension. Measuring the amplitude of liquid metal droplet is beneficial to explore the stable suspension condition of droplet and improve the measurement accuracy of its thermodynamic parameters.

At present, there are mainly two types of amplitude displacement measurement: contact type and non-contact type: non-contact type is represented by traditional laser double-beam interferometer, Doppler vibrometer, laser self-mixing interferometer, ultrasonic ranging, and high-speed photography. ; The contact type has a rope-type displacement sensor that directly measures the vibration displacement, and there is also an acceleration sensor that measures the acceleration and then integrates it 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 method is more suitable for measuring the amplitude of the metal droplet. According to the literature survey, there is no report on the patent on the measurement of the amplitude of metal droplets under the condition of electromagnetic levitation. The existing patents on the metal droplet under the condition of electromagnetic levitation include: "Space rapid solidification ground simulation method and experimental device, patent number: CN1158916A ", "A method for regulating the shape of electromagnetic levitation liquid metal, patent number: CN108183632B", "An electromagnetic levitation ball system with acceleration detection function and its control method, patent number: CN110320385A", "Metal droplet Rapid solidification method, patent number: CN111230130A", "a method for measuring the oscillation frequency of metal droplets under the condition of electromagnetic levitation, patent number: CN113432700A", etc.

The metal droplet oscillates during the electromagnetic levitation refining process. Since this phenomenon has a great influence on the suspension stability of the metal droplet and the measurement results of some thermodynamic properties, it is necessary to design a method that can detect the amplitude of the suspended droplet. This method is conducive to exploring the stable suspension conditions of molten droplets and improving the accuracy and reliability of the measurement results of some thermodynamic properties.

Contents of the invention

Aiming at the problems and deficiencies in the above-mentioned prior art, the present invention provides a method for measuring the amplitude of metal droplets under the condition of electromagnetic levitation. The metal sample of the invention suspends and melts rapidly under the condition of electromagnetic levitation, and the non-contact levitation condition avoids the interference of the container wall to the amplitude measurement, and can measure the amplitude of the metal droplet with high melting point under the condition of high temperature oscillation. The present invention is realized through the following technical solutions.

The invention uses electromagnetic levitation containerless technology and a method for measuring the amplitude of metal droplets with a high-speed camera, designs a new method for measuring the amplitude of suspended metal droplets, and realizes the measurement of the amplitude of molten droplets under the condition of electromagnetic levitation of high melting point metal alloy materials. In order to avoid the deficiencies of the prior art, the present invention proposes a method for measuring the amplitude of electromagnetic levitation liquid metal, which is levitated, heated and melted through a specially designed electromagnetic levitation coil, and then image acquisition and data processing analysis are performed to determine The droplet amplitude on the surface.

A method for measuring the amplitude of metal droplets under electromagnetic levitation conditions, the specific steps comprising:

Step 1. Place the sample to be measured in the electromagnetic levitation equipment, suspend the sample to be measured by controlling the electromagnetic levitation conditions to obtain suspended molten droplets 2, and obtain continuous multiple oscillations by shooting with the high-speed camera 6 of the electromagnetic levitation equipment Picture: The suspension coil 3 in the electromagnetic levitation equipment is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten drop 2, the high-speed camera 6 shoots the suspended molten drop, the infrared thermometer 4 and the high-speed camera The instrument 6 is connected to the computer system 5 for data recording and processing.

Specifically:

Step 1.1, place the sample to be measured in the suspension coil 3, adjust the infrared thermometer 4 to make it focus on the sample position, adjust the focal length of the high-speed camera 6 so that the sample can be clearly photographed, and turn on the gas processing system 1 Spray the sample for 3-5 minutes to provide a protective atmosphere;

Step 1.2, turn on the power control system 7, the sample is suspended in the center of the suspension coil 3 under the action of the high-frequency alternating magnetic field and gradually heat up, increase the output power of the power control system 7 until the reading of the infrared thermometer 4 is greater than the sample melting point, and the high-speed camera 6 can be used to observe that the sample changes from an irregular shape to an ellipsoid, and a suspended droplet 2 is obtained;

Step 2. Actively save the multiple consecutive oscillating pictures obtained in step 1 into the file specified by the computer, and then use the computer MATLAB software to program the oscillating pictures. Specifically, the program reads the picture information from the corresponding file, Locate the object (droplet) in the image, generate a thumbnail by downsampling and mark and display the outline of the object, perform threshold segmentation according to the different gray levels of the target image and the background, and perform noise reduction processing on the image to remove Image interference, extracting the connected components of the binary image, determining and displaying the processed image information;

Step 3. Obtain a diagram of the variation of the oscillation position by counting and recording the oscillation positions in the n oscillation cycles of the suspended melt droplet 2 on the continuous multiple oscillation pictures processed in step 2, the oscillation peak and the bottom in the upper part of the oscillation position variation diagram The trough is marked with a triangle. The amplitude value of this oscillation is the adjacent peak minus the trough. It is calculated by formula (1), and the maximum value of the amplitude and the average value of the amplitude are obtained by formula (2) :

A _i ＝ A i _∧ -A i _∨ (1);

A _max = max(A _i ) (2);

Among them, A _i is the amplitude value of the i-th cycle of the suspended droplet 2, A _i∧ is the peak value of the oscillation wave of the i-th cycle of the suspended droplet 2, A _i∨ is the oscillation valley value of the i-th cycle of the suspended droplet 2; A _max is Amplitude maximum value; A _ave is the average amplitude value of the suspended droplet, unit: pixel; n is the number of oscillation cycles of the suspended droplet.

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

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

The protective gas fed into the gas treatment system 1 in the above step 1.1 is one of argon, helium or a mixture of the two in any volume, and the gas flow rate can be 0.1L/min-5.0L/min.

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.

The beneficial effects of the present invention are:

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

2. The present invention uses electromagnetic levitation containerless technology, high-speed camera image acquisition and computer data processing, which can simultaneously collect and measure the amplitude of high-temperature metal droplets in the upper and lower directions and left and right directions of suspended molten droplets, and can realize the measurement of suspended molten droplets in two directions. Online measurement of amplitude.

3. The device can not only measure the droplet amplitude under high temperature conditions but also has high resolution. The non-contact measurement method makes it not affected by the container wall, which is conducive to the study of the suspension stability of high-temperature droplets. At the same time, the device also has the advantages of simple structure, rapid measurement, etc., and has a good application prospect.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the present invention to measure the amplitude of the high temperature metal alloy under the condition of electromagnetic levitation;

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

Fig. 2 is the actual figure of concrete experiment of embodiment 1 of the present invention; Among the figure (a) is 3 representative figures that obtain after the picture processing of metal molten droplet suspension; (b) is the camera picture with scale; (c) is left and right and Oscillating waveforms in up and down directions.

Fig. 3 is the actual figure of concrete experiment of embodiment 2 of the present invention; Among the figure (a) is 3 representative figures that obtain after the picture processing of metal droplet suspension; (b) is the photographic picture with scale; (c) is left and right and Oscillating waveforms in up and down directions.

Fig. 4 is the actual figure of concrete experiment of embodiment 3 of the present invention; Among the figure (a) is 3 representative figures that obtain after the picture processing of metal droplet suspension; (b) is the videograph with scale; (c) is left and right and Oscillating waveforms in up and down directions.

detailed description

The present invention will be further described below in combination with the accompanying drawings and specific embodiments.

Example 1

As shown in Figure 1, the method for measuring the amplitude of metal droplets under the condition of electromagnetic levitation, its specific steps include:

Step 1. Place the sample to be measured in the electromagnetic levitation equipment, suspend the sample to be measured by controlling the electromagnetic levitation conditions to obtain suspended molten droplets 2, and obtain continuous multiple oscillations by shooting with the high-speed camera 6 of the electromagnetic levitation equipment Picture: The suspension coil 3 in the electromagnetic levitation equipment is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten drop 2, the high-speed camera 6 shoots the suspended molten drop, the infrared thermometer 4 and the high-speed camera The instrument 6 is connected to the computer system 5 for data recording and processing.

Specifically:

Step 1.1, place the sample to be measured (titanium aluminum alloy particles, 1.8g) in the suspension coil 3, adjust the infrared thermometer 4 so that its focus is on the sample position, and adjust the focal length of the high-speed camera 6 so that it can Take a clear picture of the sample, turn on the gas treatment system 1 and 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 1.5L/min);

Step 1.2, pour cooling water into the suspension coil 3, turn on the power control system 7 (current is 374A, power frequency 297kHz, power 5.6kW), and the sample is suspended in the center of the suspension coil 3 under the action of a high-frequency alternating magnetic field And gradually heat up, increase the output power of the power control system 7 until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the high-speed camera 6 can be used to observe that the sample changes from an irregular shape to an ellipsoid, and a suspended droplet is obtained 2;

Step 2. Actively save the multiple consecutive oscillating pictures obtained in step 1 into the file specified by the computer, and then use the computer MATLAB software to program the oscillating pictures. Specifically, the program reads the picture information from the corresponding file, Locate the object (droplet) in the image, generate a thumbnail by downsampling and mark and display the outline of the object, perform threshold segmentation according to the different gray levels of the target image and the background, and perform noise reduction processing on the image to remove Image interference, extracting the connected components of the binary image, determining and displaying the processed image information, and obtaining several representative pictures after image processing are shown in Figure 2(a);

Step 3. Obtain a diagram of the variation of the oscillation position by counting and recording the oscillation positions in the n oscillation cycles of the suspended melt droplet 2 on the continuous multiple oscillation pictures processed in step 2, the oscillation peak and the bottom in the upper part of the oscillation position variation diagram The trough is marked with a triangle. The amplitude value of this oscillation is the adjacent peak minus the trough. It is calculated by formula (1), and the maximum value of the amplitude and the average value of the amplitude are obtained by formula (2) :

A _i ＝ A i _∧ -A i _∨ (1);

A _max = max(A _i ) (2);

Among them, A _i is the amplitude value of the i-th cycle of the suspended droplet 2, A _i∧ is the peak value of the oscillation wave of the i-th cycle of the suspended droplet 2, A _i∨ is the oscillation valley value of the i-th cycle of the suspended droplet 2; A _max is Amplitude maximum value; A _ave is the average amplitude value of the suspended droplet, unit: pixel; n is the number of oscillation cycles of the suspended droplet.

In this embodiment, according to the camera picture with a scale as shown in Figure 2 (b), its resolution is 1920*1080 pixels, and the pixel difference corresponding to 1 cm on the scale is 493-291=202 pixels, and each pixel can be calculated 0.050mm. As shown in Figure 2(c), according to the formula (1), the amplitude value in the left and right directions (ie, the X direction) and the amplitude value in the up and down direction (ie, the Y direction) are calculated. According to the formulas (2) and (3), it can be obtained: titanium aluminum When the alloy suspended droplet is at 1950°C, the maximum amplitude of oscillation in the left and right direction is 33.03 pixels or 1.65mm, the average amplitude is 9.75 pixels or 0.49mm, the maximum amplitude of the oscillation in the up and down direction is 9.32 pixels or 0.47mm, and the average amplitude is 3.78 pixels or 0.19mm.

Example 2

As shown in Figure 1, the method for measuring the amplitude of metal droplets under the condition of electromagnetic levitation, its specific steps include:

Step 1. Place the sample to be measured in the electromagnetic levitation equipment, suspend the sample to be measured by controlling the electromagnetic levitation conditions to obtain suspended molten droplets 2, and obtain continuous multiple oscillations by shooting with the high-speed camera 6 of the electromagnetic levitation equipment Picture: The suspension coil 3 in the electromagnetic levitation equipment is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten drop 2, the high-speed camera 6 shoots the suspended molten drop, the infrared thermometer 4 and the high-speed camera The instrument 6 is connected to the computer system 5 for data recording and processing.

Specifically:

Step 1.1, place the sample to be measured (ferrosilicon alloy particles, 1.3g) in the suspension coil 3, adjust the infrared thermometer 4 to make it focus on the sample position, adjust the focal length of the high-speed camera 6 to make it clear Photograph the sample, turn on the gas treatment system 1 and 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 1.5L/min);

Step 1.2, pour cooling water into the suspension coil 3, turn on the power control system 7 (current is 374A, power frequency 297kHz, power 5.6kW), and the sample is suspended in the center of the suspension coil 3 under the action of a high-frequency alternating magnetic field And gradually heat up, increase the output power of the power control system 7 until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the high-speed camera 6 can be used to observe that the sample changes from an irregular shape to an ellipsoid, and a suspended droplet is obtained 2;

Step 2. Actively save the multiple consecutive oscillating pictures obtained in step 1 into the file specified by the computer, and then use the computer MATLAB software to program the oscillating pictures. Specifically, the program reads the picture information from the corresponding file, Locate the object (droplet) in the image, generate a thumbnail by downsampling and mark and display the outline of the object, perform threshold segmentation according to the different gray levels of the target image and the background, and perform noise reduction processing on the image to remove Image interference, extract the connected components of the binary image, determine and display the processed image information, and obtain several representative pictures after image processing, as shown in Figure 3(a);

Step 3. Obtain a diagram of the variation of the oscillation position by counting and recording the oscillation positions in the n oscillation cycles of the suspended melt droplet 2 on the continuous multiple oscillation pictures processed in step 2, the oscillation peak and the bottom in the upper part of the oscillation position variation diagram The trough is marked with a triangle. The amplitude value of this oscillation is the adjacent peak minus the trough. It is calculated by formula (1), and the maximum value of the amplitude and the average value of the amplitude are obtained by formula (2) :

A _i ＝ A i _∧ -A i _∨ (1);

A _max = max(A _i ) (2);

Among them, A _i is the amplitude value of the i-th cycle of the suspended droplet 2, A _i∧ is the peak value of the oscillation wave of the i-th cycle of the suspended droplet 2, A _i∨ is the oscillation valley value of the i-th cycle of the suspended droplet 2; A _max is Amplitude maximum value; A _ave is the average amplitude value of the suspended droplet, unit: pixel; n is the number of oscillation cycles of the suspended droplet.

In this embodiment, according to the camera picture with a scale as shown in Figure 3 (b), its resolution is 1920*1080 pixels, and the pixel difference corresponding to 1 cm on the scale is 423-299=224 pixels, and each pixel can be calculated is 0.045mm. As shown in Figure 3(c), according to the formula (1), the amplitude value in the left and right directions (ie, the X direction) and the amplitude value in the up and down direction (ie, the Y direction) are calculated. According to the formulas (2) and (3), it can be obtained: ferrosilicon alloy When the suspended droplet is at 1900°C, the maximum amplitude of oscillation in the left and right direction is 22.65 pixels or 1.02mm, and the average amplitude is 4.35 pixels or 0.196mm; the maximum amplitude of oscillation in the up and down direction is 4.47 pixels or 0.20mm, and the average amplitude is 1.38 pixels or 0.06 mm.

Example 3

As shown in Figure 1, the method for measuring the amplitude of metal droplets under the condition of electromagnetic levitation, its specific steps include:

Step 1. Place the sample to be measured in the electromagnetic levitation equipment, suspend the sample to be measured by controlling the electromagnetic levitation conditions to obtain suspended molten droplets 2, and obtain continuous multiple oscillations by shooting with the high-speed camera 6 of the electromagnetic levitation equipment Picture: The suspension coil 3 in the electromagnetic levitation equipment is connected to the power control system 7, the infrared thermometer 4 measures the temperature of the suspended molten drop 2, the high-speed camera 6 shoots the suspended molten drop, the infrared thermometer 4 and the high-speed camera The instrument 6 is connected to the computer system 5 for data recording and processing.

Specifically:

Step 1.1, place the sample to be measured (pure iron particles, 1.9g) in the suspension coil 3, adjust the infrared thermometer 4 to make it focus on the sample position, adjust the focal length of the high-speed camera 6 to make it clear Photograph the sample, turn on the gas treatment system 1 and 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 1.5L/min);

Step 1.2, pour cooling water into the suspension coil 3, turn on the power control system 7 (current is 374A, power frequency 297kHz, power 5.6kW), and the sample is suspended in the center of the suspension coil 3 under the action of a high-frequency alternating magnetic field And gradually heat up, increase the output power of the power control system 7 until the reading of the infrared thermometer 4 is greater than the melting point of the sample, and the high-speed camera 6 can be used to observe that the sample changes from an irregular shape to an ellipsoid, and a suspended droplet is obtained 2;

Step 2. Actively save the multiple consecutive oscillating pictures obtained in step 1 into the file specified by the computer, and then use the computer MATLAB software to program the oscillating pictures. Specifically, the program reads the picture information from the corresponding file, Locate the object (droplet) in the image, generate a thumbnail by downsampling and mark and display the outline of the object, perform threshold segmentation according to the different gray levels of the target image and the background, and perform noise reduction processing on the image to remove Image interference, extract the connected components of the binary image, determine and display the processed image information, and obtain several representative pictures after image processing as shown in Figure 4(a);

Step 3. Obtain a diagram of the variation of the oscillation position by counting and recording the oscillation positions in the n oscillation cycles of the suspended melt droplet 2 on the continuous multiple oscillation pictures processed in step 2, the oscillation peak and the bottom in the upper part of the oscillation position variation diagram The trough is marked with a triangle. The amplitude value of this oscillation is the adjacent peak minus the trough. It is calculated by formula (1), and the maximum value of the amplitude and the average value of the amplitude are obtained by formula (2) :

A _i ＝ A i _∧ -A i _∨ (1);

A _max = max(A _i ) (2);

Among them, A _i is the amplitude value of the i-th cycle of the suspended droplet 2, A _i∧ is the peak value of the oscillation wave of the i-th cycle of the suspended droplet 2, A _iv is the oscillation valley value of the i-th cycle of the suspended droplet 2; A _max is the amplitude Maximum value; A _ave is the average amplitude value of the suspended droplet, unit: pixel; n is the number of oscillation cycles of the suspended droplet.

In this embodiment, according to the camera picture with a scale as shown in Figure 4 (b), its resolution is 1920*1080 pixels, and the pixel difference corresponding to 1 cm on the scale is 495-378=117 pixels, and each pixel can be calculated is 0.085mm. As shown in Figure 2(c), according to the formula (1), the amplitude value in the left and right direction (ie, the X direction) and the amplitude value in the up and down direction (ie, the Y direction) are calculated. According to the formulas (2) and (3), it can be obtained: pure iron When the suspended droplet is at 1850°C, the maximum amplitude of oscillation in the left and right direction is 24.21 pixels or 2.06mm, the average amplitude is 5.80 pixels or 0.49mm, the maximum amplitude of the oscillation in the up and down direction is 12.18 pixels or 1.04mm, and the average amplitude is 2.15 pixels or 0.18 mm.

The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Variations.

Claims (3)

1. A method for measuring the amplitude of a metal droplet under an electromagnetic suspension condition is characterized by comprising the following specific steps:

the method comprises the following steps that 1, a sample to be measured is placed in electromagnetic suspension equipment, the sample to be measured is suspended by controlling electromagnetic suspension conditions to obtain suspended molten drops (2), and continuous multiple oscillation pictures are obtained by shooting through a high-speed camera (6) of the electromagnetic suspension equipment;

step 2, programming the continuous multiple oscillation pictures shot in the step 1, specifically: reading picture information from a corresponding file, positioning an object in an image, generating a thumbnail through down-sampling, marking and displaying the outline of the object, performing threshold segmentation according to different gray levels occupied by a target image and a background, performing noise reduction processing on the image to remove image interference, extracting a connected component of a binary image, and determining and displaying the processed image information;

step 3, obtaining an oscillation position change situation graph by counting and recording oscillation positions of the continuous oscillation pictures processed in the step 2 in n oscillation periods of the suspended molten drop (2), wherein an oscillation peak at the upper part and a trough at the bottom in the oscillation position change situation graph are marked by triangles, the amplitude value of the current oscillation is obtained by subtracting the trough from an adjacent peak, the calculation is carried out through a formula (1), and the maximum amplitude value and the average amplitude value are obtained through the formula (2) and the formula (3):

A _i ＝A _i∧ -A _i∨ (1)；

A _max ＝max(A _i ) (2)；

wherein A is _i Amplitude value of ith cycle of suspended molten drop (2), A _i∧ Is the ith periodic oscillation wave peak value of the suspended molten drop (2), A _i∨ The ith periodic oscillation wave valley value of the suspended molten drop (2); a. The _max Is the maximum amplitude; a. The _ave Is the average amplitude value of the suspended molten drop, and the unit is: a pixel; n is the oscillation period number of the suspended molten drop.

2. A method of measuring the amplitude of a metal droplet in electromagnetic suspension according to claim 1, wherein: the sample to be measured in the step 1 is a conductor or a semiconductor, the melting point temperature of the sample can be 800-3000K, and the mass of the prepared granular sample is 0.5-3g.

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

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