Multi-point calculation correction method for a fisher particle size analyzer

Abstract

The application discloses a multi-point correction method of a Fisher particle size analyzer, wherein a high-low value standard tube is used, the diameter or depth of a through hole is changed, and the calibration value of the standard tube is designed and controlled; when the standard tube is used for correction, the final value of a needle valve is calculated, then the needle valve is adjusted to the calculated value, so that the pressure ratio of gas passing through the standard tube is equal to the calibration value; the water level of a pressure stabilizing tube is adjusted, so that the indication value of the standard tube is consistent with the calibration value, and thus the debugging of the to-be-corrected instrument is completed. The correction method can not only make up for the shortcomings of the traditional single-point correction method, but also simplify and supplement the existing multi-point correction method, simply and quickly debug the system difference between instruments, improve the instrument correction efficiency, and provide stable guarantee for accurate regulation and control of product quality.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy and the detection and analysis technology of metal powders, and more specifically to a multi-point calculation and calibration method for a Fisher particle size analyzer. Background Technology

[0002] The Fisher particle size analyzer is a powder particle size measurement instrument designed based on the principle of air permeation. Furthermore, the standard substances used in the Fisher analyzer are employed to ensure the accuracy and repeatability of its measurement results.

[0003] According to existing publicly available technology, the Fisher particle size analyzer can be calibrated using either a single-point calibration method with a ruby ​​standard tube or a multi-point calibration method with standard substances, with adjustments made at certain intervals. The single-point calibration method with a ruby ​​standard tube assumes that the air pressure p (equal to the air pressure of a 50cm water column in a pressure-stabilizing tube) before the sample passes through the instrument is consistent. The needle valve is adjusted to change the valve coefficient c to calibrate a single instrument. According to the published patent CN 114018768A, the multi-point calibration method with standard substances supplements the single-point calibration method with adjustments made to compensate for pressure losses in different Fisher particle size analyzers and different equipment pipelines. It uses two or more high and low standard substances, first adjusting the needle valve coefficient c, and then changing the p value before the sample passes by adjusting the water level in the pressure-stabilizing tube to eliminate system differences between instruments. However, the multi-point calibration method requires continuous adjustment of the needle valve and calculation of the pressure ratio K after the gas passes through standard substance A and standard substance B. Furthermore, the U-shaped pressure gauge water level change caused by rotating the needle valve often has a lag, requiring repeated adjustments and calculations, which is time-consuming and labor-intensive.

[0004] Standard materials for Fisher particle size analyzers are crucial and necessary in practical applications. Firstly, using standard materials with known dimensions and calibration values ​​allows for the evaluation of instrument performance and biases. Secondly, using the same standard material verifies differences between different models of Fisher particle size analyzers, assessing the consistency and comparability between instruments, which is significant for quality control and product development. Since the early Fisher 95 particle size analyzer and its accompanying ruby ​​standard tubes used in the industry are discontinued, and publicly available calibration methods using ruby ​​tubes as standard tubes are expensive and difficult to manufacture; using powder particles as calibration materials cannot guarantee long-term stability of the powder's performance, and fluctuations in standard values ​​will hinder product quality control and cause production inconvenience. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a multi-point calculation and calibration method for a Fisher particle size analyzer. This method can not only make up for the shortcomings of the traditional single-point calibration method, but also simplify and supplement the existing multi-point calibration method. It can easily and quickly adjust the system differences between instruments, improve the calibration efficiency of the instruments, and provide a stable guarantee for the precise control of product quality.

[0006] The technical solution adopted by this invention to solve the technical problem is: a multi-point calculation and calibration method for a Fisher particle size analyzer. The calibration method involves using high and low value standard tubes and designing and controlling the calibration value of the standard tubes by changing the diameter or depth of the through holes. When using the standard tubes for calibration, the final adjustment value of the needle valve is first calculated, and then the needle valve is adjusted to the calculated value so that the pressure ratio of the gas after passing through the standard tube is equal to the calibration value. Then, the water level of the pressure stabilizing tube is adjusted so that the reading of the standard tube is consistent with the calibration value, thereby completing the debugging of the instrument to be calibrated.

[0007] Furthermore, the correction method specifically includes the following steps:

[0008] a) Using the instrument to be calibrated, measure the Fisher particle size values ​​d1 and d2 of the high and low standard tubes;

[0009] b) Adjust the needle valve. Calculate the required reading using the Kozeny-Carman equation, as follows:

[0010] 1) Using d 1标 and d 2标 Calculate F 1标 F 2标 , and F 1标 F 2标 The ratio K 标 ;

[0011] 2) Using d1 and d2, calculate F1, F2, and the ratio K of F1 and F2;

[0012] 3) Adjust the needle valve so that K and K 标 Equal, this will cause the needle valve coefficient c to change; K 标 Substituting K, d1, and d2 into the calculation, we obtain c' after adjusting the needle valve; substituting K, d1, and d2 into the calculation, we obtain the initial c.

[0013] 4) Substitute c', d1, and d2 into the calculation to obtain F1' and F2' after adjusting the needle valve;

[0014] 5) Substitute c, F1', and F2' into the calculation to obtain d1' and d2' after adjusting the needle valve;

[0015] c) Adjust the needle valve according to the calculation results so that the readings of the high and low standard tubes are d1' and d2';

[0016] d) Adjust the water level in the pressure stabilizing pipe by adding or removing water until the error between the measured and calibrated values ​​of the high and low standard pipes is within ±3%.

[0017] e) After the first gear is adjusted, adjust the second gear; the adjustment steps are shown in a to d.

[0018] Furthermore, in the method described above, the formula for calculating the Fisher particle size using the Kozeny-Carman equation is as follows:

[0019]

[0020] Where d is the Fsss value of the sample or standard tube, and when the sample is powder, d is the particle size of the powder; c is a coefficient related to the instrument, adjusted by rotating the needle valve; p is the air pressure before the sample bed or standard tube, controlled by increasing or decreasing the water level in the pressure stabilizing tube; F is the air pressure after the sample bed or standard tube, read from the water column of the U-tube manometer; L is the thickness of the sample layer; and A is the cross-sectional area of ​​the sample layer, taken as a constant of 1.267 cm². 2 .

[0021] Furthermore, the high and low standard tubes are made of a material resistant to water vapor corrosion and with a low coefficient of thermal expansion, including but not limited to stainless steel; the high and low standard tubes are hollow cylinders, and each high and low standard tube includes an outer wall and an inner wall, the roughness of which is Ra 1.5~1.7μm; the high and low standard tubes have one or more partition layers in the middle; each partition layer has a through hole running vertically through it.

[0022] Furthermore, based on the principle of air permeability, gas molecules collide and rub against each other when passing through the pores. The size and depth of the pores determine the size and length of the channel through which gas molecules pass. When the pore is large and short, the resistance is small; conversely, when the pore is small and long, the resistance to gas passage increases, thus affecting the air pressure before and after passing through the sample bed. Therefore, the diameter of the pore is directly proportional to the Fsss value of the standard tube, and the length of the pore is inversely proportional to the Fsss value of the standard tube. The diameter and depth of the pores in the high-value standard tube are designed according to the calibration values; the porosity is Por. 1标 The Fsss value is d 1标 Similarly, the diameter and depth of the through-hole in the low-value standard pipe are designed according to the calibration values; the porosity is Por. 2标 The Fsss value is d 2标 .

[0023] Furthermore, the calibration method is applicable to Fisher particle size analyzers designed based on the principle of air permeation.

[0024] Furthermore, the calibration method is applicable to calibrating other Fisher instruments using the measurement value of one Fisher instrument as the calibration value.

[0025] The beneficial effects of this invention are as follows: Compared with the prior art, the multi-point calculation and calibration method for Fisher particle size analyzers provided by this invention uses high and low standard tubes made of materials resistant to water vapor corrosion and with low thermal expansion coefficients (such as stainless steel) as calibration materials. These tubes have the advantage of stable physicochemical properties, can maintain good structure and hardness for a long time, are easy to process, and are relatively inexpensive. Furthermore, this invention utilizes the principle of the Kozeny-Carman equation to calculate the final value that the needle valve needs to be adjusted to in the multi-point calibration method, simplifying the needle valve adjustment and eliminating the need for repeated calculations of the pressure ratio K. This significantly shortens the adjustment time of the multi-point calibration method, improves the calibration efficiency of the Fisher particle size analyzer, and makes the calibration process of both American Fisher and domestically produced Fisher particle size analyzers simpler and faster. Moreover, the detection difference within the 0.5–50 μm range is within ±3%. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the cross-sectional structure of a single-layer stainless steel standard tube provided in Example 1.

[0027] Figure 2 This is a schematic diagram of the cross-sectional structure of the multilayer stainless steel standard tube provided in Example 2.

[0028] Among them, 1-stainless steel outer wall, 2-stainless steel inner wall, 3-first partition layer, 4-through hole, 5-second partition layer, and 6-third partition layer. Detailed Implementation

[0029] The present invention will be further illustrated below with specific embodiments. However, these examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] A multi-point calculation and calibration method for a Fisher particle size analyzer is disclosed. The calibration method involves using high and low value standard tubes and adjusting the calibration value of the standard tubes by changing the diameter or depth of the through-holes. When using the standard tubes for calibration, the final adjustment value of the needle valve is first calculated, and then the needle valve is adjusted to the calculated value so that the pressure ratio of the gas after passing through the standard tube is equal to the calibration value. Then, the water level of the pressure stabilizing tube is adjusted so that the reading of the standard tube is consistent with the calibration value, thereby completing the calibration of the instrument to be calibrated.

[0031] Furthermore, the correction method specifically includes the following steps:

[0032] a) Using the instrument to be calibrated, measure the Fisher particle size values ​​d1 and d2 of the high and low standard tubes;

[0033] b) Adjust the needle valve. Calculate the required reading using the Kozeny-Carman equation, as follows:

[0034] 1) Using d 1标 and d2标 Calculate F 1标 F 2标 , and F 1标 F 2标 The ratio K 标 ;

[0035] 2) Using d1 and d2, calculate F1, F2, and the ratio K of F1 and F2;

[0036] 3) Adjust the needle valve so that K and K 标 Equal, this will cause the needle valve coefficient c to change; K 标 Substituting K, d1, and d2 into the calculation, we obtain c' after adjusting the needle valve; substituting K, d1, and d2 into the calculation, we obtain the initial c.

[0037] 4) Substitute c', d1, and d2 into the calculation to obtain F1' and F2' after adjusting the needle valve;

[0038] 5) Substitute c, F1', and F2' into the calculation to obtain d1' and d2' after adjusting the needle valve;

[0039] c) Adjust the needle valve according to the calculation results so that the readings of the high and low standard tubes are d1' and d2';

[0040] d) Adjust the water level in the pressure stabilizing pipe by adding or removing water until the error between the measured and calibrated values ​​of the high and low standard pipes is within ±3%.

[0041] e) After the first gear is adjusted, adjust the second gear; the adjustment steps are shown in a to d.

[0042] Furthermore, in the method described above, the formula for calculating the Fisher particle size using the Kozeny-Carman equation is as follows:

[0043]

[0044] Where d is the Fsss value of the sample or standard tube, and when the sample is powder, d is the particle size of the powder; c is a coefficient related to the instrument, adjusted by rotating the needle valve; p is the air pressure before the sample bed or standard tube, controlled by increasing or decreasing the water level in the pressure stabilizing tube; F is the air pressure after the sample bed or standard tube, read from the water column of the U-tube manometer; L is the thickness of the sample layer; and A is the cross-sectional area of ​​the sample layer, taken as a constant of 1.267 cm². 2 .

[0045] Furthermore, the high and low standard tubes are made of a material resistant to water vapor corrosion and with a low coefficient of thermal expansion, including but not limited to stainless steel; the high and low standard tubes are hollow cylinders, and each high and low standard tube includes an outer wall and an inner wall, the roughness of which is Ra 1.5~1.7μm; the high and low standard tubes have one or more partition layers in the middle; each partition layer has a through hole running vertically through it.

[0046] Furthermore, the diameter and depth of the through-hole in the high-value standard pipe are designed according to the calibration value; the porosity is Por. 1标 The Fsss value is d 1标 .

[0047] Furthermore, the diameter and depth of the through-hole in the low-value standard pipe are designed according to the calibration value; the porosity is Por. 2标 The Fsss value is d 2标 .

[0048] Furthermore, the calibration method is applicable to Fisher particle size analyzers designed based on the principle of air permeation.

[0049] Furthermore, the calibration method is applicable to calibrating other Fisher instruments using the measurement value of one Fisher instrument as the calibration value.

[0050] Example 1

[0051] In this embodiment, a single-layer stainless steel high and low standard tube is used, and the standard tube is a hollow cylinder. The single-layer stainless steel high and low standard tube includes a stainless steel outer wall 1 and a stainless steel inner wall 2. The roughness of the stainless steel inner wall 2 is Ra 1.6μm. A first partition layer 3 is provided in the middle of the single-layer stainless steel high and low standard tube. A through hole 4 is provided in the first partition layer 3.

[0052] The WLP-208 Dandong Fisher particle size analyzer was calibrated using the Fisher 95 as the standard. The specific calibration method was as follows: both instruments were set to their lowest settings, and calibration was performed using two single-layer stainless steel standard tubes. Single-layer stainless steel tube one was a high-value standard tube with a stainless steel through-hole diameter of 150 μm and a hole depth of 6 mm; single-layer stainless steel tube two was a low-value standard tube with a stainless steel through-hole diameter of 150 μm and a hole depth of 10 mm.

[0053] The Fsss values ​​of single-layer stainless steel tube one and single-layer stainless steel tube two were measured on Fisher 95 and WLP-208 instruments, respectively. The p, K, and c values ​​of the two Fisher instruments were calculated according to formula (1). Substituting the results into the calculation, the particle size values ​​d1 and d2 that the needle valve of the WLP-208 instrument needs to be adjusted to were obtained. Next, the needle valve of the WLP-208 instrument was rotated to the low setting until the readings were d1 and d2. At this time, K... Fisher 95=K WLP-208 Then adjust the water level in the pressure stabilizing pipe to make the Fisher particle size values ​​of single-layer stainless steel standard tube one and single-layer stainless steel standard tube two consistent on both instruments.

[0054] Both instruments were set to high settings, and calibration was performed using single-layer stainless steel standard tube one and single-layer stainless steel standard tube two. The Fsss values ​​of single-layer stainless steel tube one and single-layer stainless steel tube two were measured on the Fisher 95 and WLP-208 instruments, respectively. The p, K, and c values ​​of the two Fisher instruments were calculated using Formula 1. Substituting the results into the calculation, the required particle size values ​​d3 and d4 for the needle valve of the WLP-28 instrument were obtained. Next, the needle valve of the WLP-208 instrument was rotated to its high setting until the readings were d3 and d4. At this point, K... Fisher 95 =K WLP-208 Then adjust the water level in the pressure stabilizing pipe to make the Fisher particle size values ​​of single-layer stainless steel standard tube one and single-layer stainless steel standard tube two consistent on both instruments.

[0055] Table 1 shows the data of tungsten carbide samples measured by the American Fisher 95 particle size analyzer and the domestic WLP-208 Dandong Fisher particle size analyzer after debugging:

[0056] Table 1. Tungsten carbide measurement data of domestic and imported Fisher instruments.

[0057] 1 0.72 0.73 -1.37％ 2 0.95 0.95 0.00％ 3 1.57 1.59 -1.26％ 4 1.66 1.68 -1.19％ 5 3.00 2.98 0.67％ 6 4.22 4.20 0.48％ 7 4.65 4.60 1.09％ 8 6.25 6.20 0.81％ 9 10.0 9.90 1.01％ 10 24.6 24.8 -0.81％

[0058] The above calibration method utilizes the principle of the Kozeny-Carman equation to calculate the final value that the needle valve needs to be adjusted to in the multi-point calibration method, simplifying the adjustment of the needle valve and eliminating the need for repeated calculation of the pressure ratio K. This greatly shortens the adjustment time of the multi-point calibration method, improves the calibration efficiency of the Fisher particle size analyzer, and makes the calibration process of the American Fisher and the domestic Fisher particle size analyzer simpler and faster. Moreover, the detection difference in the range of 0.5 to 50 μm is within ±3%.

[0059] Example 2

[0060] In this embodiment, a multi-layer stainless steel high and low standard tube is used, and the standard tube is a hollow cylinder. The multi-layer stainless steel high standard tube includes a stainless steel outer wall 1 and a stainless steel inner wall 2. The roughness of the stainless steel inner wall 2 is Ra 1.6μm. A first partition layer 3 and a second partition layer 5 are provided in the middle of the stainless steel high standard tube. A first partition layer 3, a second partition layer 5, and a third partition layer 6 are provided in the middle of the stainless steel low standard tube. Each of the partition layers is provided with a through hole 4 that runs vertically through the tube.

[0061] The Fisher 95 particle size analyzer was used as the calibration standard to calibrate the Dandong WLP-208 Fisher particle size analyzer. The specific calibration method was as follows: both instruments were set to their lowest settings, and calibration was performed using multi-layer stainless steel standard tubes three and four. Multi-layer stainless steel tube three was a high-value standard tube, and multi-layer stainless steel tube four was a low-value standard tube. The diameter of the stainless steel through-hole in the middle of both tubes was 150 μm, and the hole depth was 2 mm.

[0062] The Fsss values ​​of multilayer stainless steel tubes three and four were measured on Fisher 95 and WLP-208 instruments, respectively. The p, K, and c values ​​of the two Fisher instruments were calculated according to formula (1). Substituting the results into the calculation, the particle size values ​​d1 and d2 that the needle valve of the WLP-208 instrument needs to be adjusted to were obtained. Next, the needle valve of the WLP-208 instrument was rotated to its lowest setting until the readings were d1 and d2. At this point, K... Fisher 95 =K WLP-208 Then adjust the water level in the pressure stabilizing pipe to make the Fisher particle size values ​​of the multi-layer stainless steel standard tube three and multi-layer stainless steel standard tube four consistent on both instruments.

[0063] Both instruments were set to high settings and calibrated using multi-layer stainless steel standard tubes three and four. The Fsss values ​​of multi-layer stainless steel tubes three and four were measured on the Fisher 95 and WLP-208 instruments, respectively. The p, K, and c values ​​of the two Fisher instruments were calculated using Formula 1. Substituting these results into the calculations, the required particle size values ​​d3 and d4 for the needle valve of the WLP-28 instrument were obtained. Next, the needle valve on the high-setting setting of the WLP-208 instrument was rotated until the readings were d3 and d4. At this point, K... Fisher 95 =K WLP-208 Then adjust the water level in the pressure stabilizing pipe to make the Fisher particle size values ​​of the multi-layer stainless steel standard tube three and multi-layer stainless steel standard tube four consistent on both instruments.

[0064] Table 2 shows the data of tungsten powder samples measured by the American Fisher 95 particle size analyzer and the domestic WLP-208 Dandong Fisher particle size analyzer after debugging:

[0065] Table 2. Tungsten Powder Measurement Data for Domestic and Imported Fisher Instruments

[0066] 1 0.65 0.65 0.00％ 2 1.02 1.04 -1.92％ 3 3.00 3.00 0.00％ 4 5.62 5.58 1.43％ 5 11.0 10.7 2.80％

[0067] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A multi-point calculation and calibration method for a Fisher particle size analyzer, characterized in that: The calibration method involves using high and low standard tubes and adjusting the calibration value of the standard tube by changing the diameter or depth of the through hole. When using the standard tube for calibration, the final adjustment value of the needle valve is first calculated, and then the needle valve is adjusted to the calculated value so that the pressure ratio of the gas after passing through the standard tube is equal to the calibration value. Then, the water level of the pressure stabilizing tube is adjusted so that the reading of the standard tube is consistent with the calibration value, thereby completing the debugging of the instrument to be calibrated. The correction method specifically includes the following steps: a) Using the instrument to be calibrated, measure the Fisher particle size values ​​d1 and d2 of the high and low standard tubes; b) Adjust the needle valve. Calculate the required reading using the Kozeny-Carman equation, as follows: 1) Using the calibration value d of the high and low standard pipes 1标 and d 2标 Calculate F 1标 F 2标 , and F 1标 F 2标 The ratio K 标 ; 2) Using d1 and d2, calculate F1, F2, and the ratio K of F1 and F2; 3) Adjust the needle valve so that K and K 标 Equal, this will cause the needle valve coefficient c to change; K 标 Substituting K, d1, and d2 into the calculation, we obtain c' after adjusting the needle valve; substituting K, d1, and d2 into the calculation, we obtain the initial c. 4) Substitute c', d1, and d2 into the calculation to obtain F1' and F2' after adjusting the needle valve; 5) Substitute c, F1', and F2' into the calculation to obtain d1' and d2' after adjusting the needle valve; c) Adjust the needle valve according to the calculation results so that the readings of the high and low standard tubes are d1' and d2'; d) Adjust the water level in the pressure stabilizing pipe by adding or removing water until the error between the measured and calibrated values ​​of the high and low standard pipes is within ±3%. e) After the first gear is debugged, the second gear is debugged; the debugging steps are shown in a~d. In the method described above, the formula for calculating the Fisher particle size using the Kozeny-Carman equation is as follows: Official (1) Where d is the Fsss value of the sample or standard tube, and when the sample is powder, d is the particle size of the powder; c is a coefficient related to the instrument, adjusted by rotating the needle valve; p is the air pressure before the sample bed or standard tube, controlled by increasing or decreasing the water level in the pressure stabilizing tube; F is the air pressure after the sample bed or standard tube, read from the water column of the U-tube manometer; L is the thickness of the sample layer; and A is the cross-sectional area of ​​the sample layer, taken as a constant of 1.267 cm². 2 .

2. The multi-point calculation and calibration method for a Fisher particle size analyzer as described in claim 1, characterized in that: The high and low standard tubes are made of a material resistant to water vapor corrosion and with a low coefficient of thermal expansion, including but not limited to stainless steel; the high and low standard tubes are hollow cylinders, and each tube includes an outer wall and an inner wall, the roughness of which is Ra1.5~1.7μm; the high and low standard tubes have one or more partition layers in the middle; each partition layer has a through hole running vertically through it.

3. The multi-point calculation and calibration method for a Fisher particle size analyzer as described in claim 1, characterized in that: The diameter of the through hole is directly proportional to the Fsss value of the standard tube, and the length of the through hole is inversely proportional to the Fsss value of the standard tube; the diameter and depth of the through hole of the high-value standard tube are designed according to the calibration value. The porosity is Por. 1标 The Fsss value is d 1标 .

4. The multi-point calculation and calibration method for a Fisher particle size analyzer as described in claim 1, characterized in that: The diameter of the through hole is directly proportional to the Fsss value of the standard tube, and the length of the through hole is inversely proportional to the Fsss value of the standard tube; the diameter and depth of the through hole of the low-value standard tube are designed according to the calibration value. The porosity is Por. 2标 The Fsss value is d 2标 .

5. The multi-point calculation and calibration method for a Fisher particle size analyzer as described in claim 1, characterized in that: The calibration method is applicable to Fisher particle size analyzers designed based on the principle of air permeation.

6. The multi-point calculation and calibration method for a Fisher particle size analyzer as described in claim 1, characterized in that: The calibration method is applicable to calibrating other Fisher instruments using the measurement value of one Fisher instrument as the calibration value.

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