System self-correction method for testing granularity of spherical ammonium perchlorate by dynamic image method

Abstract

A system self-calibration method for testing granularity of spherical ammonium perchlorate by a dynamic image method relates to the field of particle granularity analysis and quality detection accuracy, and comprises the following steps: S1, calibrating an image acquisition module; s2, selecting proper standard sample particles; s3, calibrating the pixel size corresponding to the lens multiple; s4, testing accuracy self-correction verification of a dynamic image method particle size and shape analysis system is carried out, pixel accuracy calibration is optimized, and it is guaranteed that a standard particle testing result conforms to a standard particle special quantity value; and S5, establishing a dynamic image method particle size and particle shape analysis self-calibration standard curing method.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of particle size analysis. Specifically, it is a method for self-calibrating the accuracy of equipment before a dynamic image particle size and shape analysis system tests the particle size of powders, which is used to ensure the accuracy of the particle size analysis test results. It aims to accurately and efficiently calibrate the dynamic image particle size and shape analysis system during the production process to ensure that the particle size measurement data is stable and reliable in the long term. Background Art

[0002] The dynamic image particle size and shape analysis system is currently widely used in a variety of powder preparation or application industries such as aerospace, aviation, mining, chemical, and pharmaceuticals. It is first used in the particle size test of spherical ammonium perchlorate, a bulk energetic powder material for solid propellants. Its accurate and rapid test of powder material particle size is extremely critical to the quality control of propellant products and the optimization of production processes. It is conducive to improving the reliability of test data and the reference of pre-loading test data to propellant performance.

[0003] At present, the dynamic image method particle size and shape analysis system is susceptible to force majeure factors such as equipment camera focus, optical component wear, lens distortion, sampling frequency fluctuations, and software updates, which lead to errors in the test results, thus affecting the control of powder material quality data during the production process. The calibration of the conventional dynamic image method particle size and shape analysis system requires the removal of the equipment casing, and professional manufacturers' engineers adjust the internal components of the equipment and calibrate the optical path to correct the test errors caused by component wear, optical path offset, etc. The calibration process is time-consuming and labor-intensive, and the production process needs to be interrupted. Professional equipment engineers need to be hired. The operation is cumbersome and costly, and it is difficult to meet the production continuity and high-precision production requirements. And the accuracy error of the equipment test results cannot be confirmed in time. Therefore, there is an urgent need for a fast and accurate self-calibration method for the dynamic image method particle size and shape analysis system. Summary of the invention

[0004] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and to provide a convenient, efficient and accurate self-calibration method for particle size and shape analysis using a dynamic image method, which does not require the employment of professional engineers and can be performed during the equipment operation interval, and ensures the stability and reliability of the test.

[0005] The technical solutions provided by this application are as follows:

[0006] A system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method. The dynamic image method particle size and shape analysis system includes a sample introduction system, an image acquisition module and a data processing system, including:

[0007] S1: Calibrate the image acquisition module;

[0008] S2: photographing the ruler through the image acquisition module to obtain a ruler image, and using the ruler image to calibrate the size of the pixels of the data processing system;

[0009] S3: According to the typical particle size distribution requirements of the sample particles to be tested, the distribution and particle size of the standard particles are determined, and the standard particles are used to verify the test accuracy of the dynamic image particle size and shape analysis system, obtain the standard particle test results, and calculate the error between the standard particle test results and the standard particle characteristic value;

[0010] S4: Repeat S2 and S3 until the error between the standard particle test result and the standard particle characteristic value meets the requirement.

[0011] In S1, calibrating the image acquisition module includes:

[0012] The exposure frequency and grayscale of the image acquisition module are set to ensure uniform illumination compensation in the image acquisition area corresponding to the image acquisition module.

[0013] In S2, photographing the ruler by an image acquisition module to obtain a ruler image, and using the ruler image to calibrate the size of pixels of the data processing system, including:

[0014] The ruler is fixed to the feeding port of the sample feeding system, the image acquisition module takes a picture of the ruler to obtain the ruler image, and the ruler image is sent to the data processing system;

[0015] Through the data processing system, a certain number of continuous pixels are selected on the ruler image, and the ruler scale length corresponding to the pixel is recorded.

[0016] In S3, the distribution and particle size of the standard particles are determined according to the typical particle size distribution requirements of the sample particles to be tested, including:

[0017] The particle size of the standard particles is 50%-150% of the particle size of the sample being tested;

[0018] The distribution of the standard particles is the same as that of the sample particles being tested.

[0019] In S3, the test accuracy of the dynamic image method particle size and shape analysis system is verified using standard particles to obtain the standard particle test results, including:

[0020] Clean the sample feeding system, add the standard particles evenly into the chute of the sample feeding system, start the slow vibration, and let the standard particles fall freely from the feeding port through the shooting area of ​​the image acquisition module. The image acquisition module takes a picture of the standard particles to obtain the standard particle image;

[0021] The data processing system identifies the standard particles in the standard particle image and counts the particle size of the standard particles. The volume average diameter d is calculated based on the particle size of the quasi-particles. 43 ;

[0022] Calculate the volume mean diameter d 43 The error between the standard particle characteristic value.

[0023] In S4, S2 and S3 are repeated until the error between the standard particle test result and the standard particle characteristic value meets the requirement, including:

[0024] Repeat S2 and S3 to obtain the error between the corresponding standard particle test result and the standard particle characteristic value. When the above error is satisfied, select the pixel size calibration of the data processing system corresponding to the minimum error value.

[0025] The volume average diameter d 43 The error between the standard particle characteristic value and the standard particle characteristic value is less than 0.5%, which meets the test requirements.

[0026] The method for self-calibration of a dynamic image particle size and shape analysis system comprises:

[0027] S1: Calibrate the image acquisition module to ensure uniform illumination compensation and standard grayscale distribution in the image acquisition area, and update the camera parameters in real time;

[0028] S2: Select appropriate standard sample particle specifications according to the requirements of dynamic image method sample detection;

[0029] S3: Use a ruler to calibrate the pixel size of a typical image on the device;

[0030] S4: According to the typical particle size data requirements of the test samples, the SOP procedure is established to determine the distribution type, and the selected standard particles are used to verify the algorithm accuracy of the dynamic image particle size and shape analysis system; the pixel accuracy calibration is optimized, and the operations of S3 and S4 are repeated to ensure that the standard particle test results are consistent with the standard particle characteristic values;

[0031] S5: Establish a self-calibration standard for particle size and shape analysis using the dynamic imaging method to facilitate guidance of production testing.

[0032] In summary, this application at least includes the following beneficial technical effects:

[0033] Compared with traditional technologies, the present invention has significant advantages. It can eliminate the need for frequent hiring of professional equipment engineers and the disassembly procedure during the self-calibration of the equipment, thereby reducing the cost of equipment inspection. This method has high self-calibration efficiency, and production personnel can complete the calibration independently. It is used to verify the accuracy of equipment in regular and abnormal states during daily production processes, thereby improving the stability of test results. It has been verified through experiments that the stability of the standard particle test error is controlled within an error range of <0.5%, which is lower than the technical indicator range of the equipment accuracy error ≤1%, thereby improving the reliability of the equipment test results. It reduces the time for shutdown and calibration, and provides strong data support for refined production. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a particle clear image effect picture;

[0035] Figure 2 Take a picture example for the ruler;

[0036] Figure 3 This is an example of a pixel size calibration method. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] In the embodiment of the present application, a method for self-calibration of a system for testing the particle size of spherical ammonium perchlorate using a dynamic image method is specifically disclosed. The self-calibration of a particle size and shape analysis system using a dynamic image method for testing spherical ammonium perchlorate is taken as an example to verify the feasibility and universality of the technology. Specifically, the following steps are included:

[0039] S1: Calibrate the image acquisition module to ensure uniform illumination compensation and standard grayscale distribution in the image acquisition area, and update the camera parameters in real time;

[0040] Adjust the lens focal length to make the image clear, and adjust the aperture range to make the particle image sharp and the details of the particle surface defects visible.

[0041] Adjust the grayscale and exposure parameters during the test process, and adjust the camera parameters in real time during the test process to make the captured particle images clear, maximize the shooting exposure frequency, and increase the data acquisition speed and particle quantity as much as possible to make the test results more representative. After extracting the binary image, the image is clear and the particle shape information, such as circularity, aspect ratio, etc., can be distinguished. See the image acquisition clarity effect Figure 1 .

[0042] S2: Select appropriate standard sample particle specifications according to the requirements of dynamic image method sample detection;

[0043] At present, the commonly used spherical ammonium perchlorate has three specifications: GA1 (330μm-340μm), GA2 (240μm-250μm) and GA3 (130μm-140μm). The lens is selected according to the particle size distribution range of spherical AP of different specifications. According to the particle size distribution range of spherical AP materials of different specifications, as well as the upper and lower limits of equipment measurement, a dynamic image method particle size and shape analysis system with lens magnification corresponding to materials of different particle size ranges is specially selected, so as to achieve the integrity of material particle measurement and the parallelism of test results. Table 1 shows the test range of the equipment lens currently selected for testing materials of different specifications of spherical ammonium perchlorate.

[0044] Table 1: Relationship between lens and test range

[0045]

[0046] According to the particle size range of the spherical ammonium perchlorate used, different equipment selects standard particles close to the particle size of the test material. The 1x lens and 3x lens equipment respectively select 300μm latex standard particles and 140μm latex standard particles. Standard materials with similar particle sizes can better illustrate the accuracy of the sample particle size test results.

[0047] The material of the selected standard particles must comply with JJF1006-1994 "Specifications for Primary Standard Materials" issued by the State Bureau of Technical Supervision, and there is no limit to the material.

[0048] S3: Use a fixed ruler to calibrate the device to the pixel size of a typical image.

[0049] According to the equipment and lens configuration of the dynamic image particle size and shape analysis system, fix the professional ruler to the ruler frame, insert the ruler frame into the card slot of the feeding port, adjust the light source and focal length to make the ruler image clear; save the ruler image ( Figure 2 ). For the saved ruler image, select a starting point, drag the mouse to select a certain length, fill in the actual corresponding length and the accurate lens multiple, and complete the reasonable calibration of the pixel size ( Figure 3 ).

[0050] During the pixel size calibration process, there is a large human operation error in dragging the distance, so it is necessary to calibrate the pixel calibration size to confirm the accuracy of the test result. If there is a large error between the standard particle size test result and the standard special value, and the test result is greater than >0.5%, you can drag the captured ruler image with a fixed size, enter the actual size, perform pixel calibration, and use standard particles for verification.

[0051] S4: Self-verification of the algorithm accuracy of the dynamic image method particle size and shape analysis system.

[0052] After the pixel size is calibrated, the pixel calibration accuracy of the dynamic image particle size and shape analysis system needs to be self-calibrated and verified. The main particle size parameter of spherical ammonium perchlorate currently used in solid propellants is the volume average diameter d 43 The data is used as the main reference data for propellant performance calculation. To ensure the accuracy of sample testing, the calibration data of standard particles is based on the volume distribution test results d 43 Main reference. The shape of spherical ammonium perchlorate particles is not completely spherical. Because its short diameter is relatively stable, the test results are more repeatable and accurate, and are more conducive to accurately describing the particle size and particle size distribution of the sample. Therefore, the particle size type is calculated based on the short diameter. This can better characterize the particle size and particle size distribution results of spherical ammonium perchlorate.

[0053] According to the host lens magnification and the particle size distribution of the spherical ammonium perchlorate sample, the test parameters are set according to the typical value requirements of the particle size of the spherical ammonium perchlorate sample, including the data setting of the data acquisition area in S1. The specific parameter settings are shown in Table 2.

[0054] Table 2: Parameter setting table

[0055] Serial number Parameter name Parameter settings 1 exposure 20-30 2 Grayscale 500-600 3 Analyze sequence Binarization 4 Aspect Ratio Correction Aspect Ratio Correction 1 5 Deleting a condition Remove edge grain 6 Adhesive particle handling Start identifying connected particles 7 Particle size type Short Path 8 Distribution Type Volume distribution

[0056] The algorithm self-calibration verification test of the dynamic image particle size and shape analysis system was carried out using the standard particles selected by S2. The characteristic values ​​and uncertainties of the purchased standard materials are shown in Table 3.

[0057] First, thoroughly clean the funnel, chute, material receiving drawer and other parts of the equipment to avoid the presence of particles from other samples affecting the self-calibration results. Evenly sprinkle the standard particles into the chute, spread the standard particles in a single layer, start slow vibration, and let the standard particles flow slowly. Free fall passes through the camera shooting area, collect the image of the standard particles, extract the binary value, and repeat the test three times for the same standard sample. 43 Data statistics are performed, and the mean value of the test results meets the range requirement of volume mean accuracy error <0.5% in the standard material specific value, and the self-calibration of the dynamic image particle size and shape analysis system is completed. Otherwise, it is necessary to calibrate the pixel size of S3, and then perform the standard material self-calibration verification of S4 again until the calibration result is consistent with the standard material specific value. The equipment accuracy results are shown in Table 4.

[0058] Table 3: Specific values ​​of standard substances

[0059]

[0060] Table 4: Standard material measurement results

[0061]

[0062] The test results of the standard substance are close to the results of the special value volume mean, and the accuracy error is less than 0.1%, which meets the requirement of taking the test accuracy error less than 0.5%. Therefore, the self-calibration results of the dynamic image method particle size and shape analysis system algorithm are accurate and reliable. It can meet the needs of spherical ammonium perchlorate particle size testing of different specifications.

[0063] S5: Establish a self-calibration standard for particle size and shape analysis using the dynamic imaging method to facilitate guidance of production testing.

[0064] According to the pixel calibration and standard particle verification results, the self-calibration procedure of the dynamic image method particle size and shape analysis system is established to solidify the self-calibration method. It is convenient for rapid self-calibration inspection during regular or production processes to ensure that the sample test results are accurate and reliable. It improves the accuracy of the product quality consistency inspection results in the production process and provides data support for scientific research and production research. From the current analysis of the dynamic image method for the particle size of spherical ammonium perchlorate on the combustion performance of propellants, the dynamic image method particle size and shape analysis test data is more reference and guiding. The main reasons are as follows: (1) Differences in test principles: The dynamic image method is based on the image analysis of particles and can detect some very fine particles. However, due to the difference in the standard sieve aperture and the equivalent particle size span of the adjacent two layers of sieves, the screening method has serious missed detection of particles and cannot fully characterize its particle size results or particle size distribution. (2) Particle agglomeration and dispersion: The dynamic image method has higher requirements for the dispersion state of particles and can better reflect the true particle size of the sample particles. However, the screening method test is affected by factors such as particle agglomeration and environmental humidity, and the measured particle size has serious deviations. (3) Consideration of non-spherical particles: The dynamic imaging method can accurately count the actual size of non-spherical particles. The screening method is mainly based on the sieve hole size, and there is a deviation in the measurement of non-spherical particles.

[0065] For a certain solid propellant, the statistical dynamic image method particle size and shape analysis system is compared with the test results of spherical ammonium perchlorate using the screening method in the existing national military standard 6174A "Ammonium Perchlorate Specification", and the burning rate of the propellant charge is statistically analyzed. When the GA3 particle size results do not fluctuate significantly and the ratio of GA1 to GA3 is the same, the burning rate of the batch of propellants with smaller GA1 dynamic image method particle size test results from the same manufacturer is significantly higher, and there is an obvious data regularity. The particle size test results of the screening method have no obvious regularity when there is no large fluctuation, so the accuracy of the dynamic image method test results can be better used as a calculation to characterize the burning rate of the propellant. The statistical results are shown in Table 5.

[0066] Table 5: Spherical AP particle size and propellant burning rate

[0067]

[0068]

[0069] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0070] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method, wherein the dynamic image method particle size and shape analysis system comprises a sample introduction system, an image acquisition module and a data processing system, and is characterized in that: include: S1: Calibrate the image acquisition module; S2: photographing the ruler through the image acquisition module to obtain a ruler image, and using the ruler image to calibrate the size of the pixels of the data processing system; S3: According to the typical particle size distribution requirements of the sample particles to be tested, the distribution and particle size of the standard particles are determined, and the standard particles are used to verify the test accuracy of the dynamic image particle size and shape analysis system, obtain the standard particle test results, and calculate the error between the standard particle test results and the standard particle characteristic value; S4: Repeat S2 and S3 until the error between the standard particle test result and the standard particle characteristic value meets the requirement.

2. A system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 1, characterized in that: In S1, calibrating the image acquisition module includes: The exposure frequency and grayscale of the image acquisition module are set to ensure uniform illumination compensation in the image acquisition area corresponding to the image acquisition module.

3. A system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 1, characterized in that: In S2, photographing the ruler by an image acquisition module to obtain a ruler image, and using the ruler image to calibrate the size of pixels of the data processing system, including: The ruler is fixed to the feeding port of the sample feeding system, the image acquisition module takes a picture of the ruler to obtain the ruler image, and the ruler image is sent to the data processing system; Through the data processing system, a certain number of continuous pixels are selected on the ruler image, and the ruler scale length corresponding to the pixel is recorded.

4. The system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 1, characterized in that: In S3, the distribution and particle size of the standard particles are determined according to the typical particle size distribution requirements of the sample particles to be tested, including: The particle size of the standard particles is 50%-150% of the particle size of the sample being tested; The distribution of the standard particles is the same as that of the sample particles being tested.

5. The system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 1, characterized in that: In S3, the test accuracy of the dynamic image method particle size and shape analysis system is verified using standard particles to obtain the standard particle test results, including: Clean the sample feeding system, add the standard substance evenly into the chute of the sample feeding system, start the slow vibration, and let the standard particles fall freely from the feeding port through the shooting area of ​​the image acquisition module. The image acquisition module takes a picture of the standard particles to obtain the standard particle image; The data processing system identifies the standard particles in the standard particle image and counts the particle size of the standard particles. The volume average diameter d is calculated based on the particle size of the quasi-particles. 43 ; Calculate the volume mean diameter d 43 The error between the standard particle characteristic value.

6. A system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 1 or 5, characterized in that: In S4, S2 and S3 are repeated until the error between the standard particle test result and the standard particle characteristic value meets the requirement, including: Repeat S2 and S3 to obtain the error between the corresponding standard particle test result and the standard particle characteristic value. When the above error is satisfied, select the pixel size calibration of the data processing system corresponding to the minimum error value.

7. The system self-calibration method for testing the particle size of spherical ammonium perchlorate by a dynamic image method according to claim 5, characterized in that: The volume average diameter d 43 The error between the standard particle characteristic value and the standard particle characteristic value is less than 0.5%, which meets the test requirements.

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