Method for measuring wrapping density of solid

Abstract

The invention discloses a method for measuring the wrapping density of a solid, and relates to the technical field of density measurement, and the method comprises the following steps: measuring the inner diameter of a first measurement container, and adding a measurement medium with a preset particle size into the first measurement container; placing a pressurizing piston on the measuring medium, and measuring a first height of the measuring medium; weighing the solid to be measured to obtain the mass of the solid; moving a part of the measurement medium into a second measurement container, placing the solid to be measured on the other part of the measurement medium, adding a part of the measurement medium, and completely covering the solid to be measured to obtain a mixed solid; placing a pressurizing piston on the mixed solid, and measuring a second height of the mixed solid; based on the inner diameter, the solid mass, the first height and the second height, the wrapping density of the to-be-measured solid is calculated, and the technical problem that in the density measurement process of a gas replacement method and a liquid drainage method in the prior art, liquid or gas media permeate into the inner hole and the closed outer hole, and consequently measurement is inaccurate can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of density measurement, and particularly to a method for measuring the bulk density of solids. Background Art

[0002] The bulk density of a solid refers to the density measured when the solid material includes its pores. The bulk density is usually used to characterize the overall density of a solid material, including its internal pore structure, and is an important property of the solid. Applications of bulk density measurement are involved in various fields such as pharmaceuticals, food, chemicals, construction, and mining; for example, in drug research and development, the bulk density is one of the important parameters for evaluating the quality of drug powders and preparations. By measuring the bulk density, the compression performance, filling performance, and performance in preparations of drugs can be understood, thereby optimizing the preparation process and performance of drugs. In addition, the bulk density can also be used to evaluate the pore structure and permeability of materials, which is of great significance for the design and application of porous materials.

[0003] Generally, the mass of a solid is easily obtained accurately. However, due to the difficulty in measuring the bulk volume, the bulk density of the solid cannot be accurately obtained ultimately. The pore categories of the solid to be measured include internal pores, closed external pores, and open external pores. Currently, the bulk density can be measured by the gas displacement method and the liquid displacement method. However, during the measurement process of the gas displacement method and the liquid displacement method, the liquid or gas medium will penetrate into the internal pores and closed external pores, resulting in inaccurate measurement. What is measured is the volume of the solid skeleton, and the bulk volume cannot be accurately measured, leading to the inability to accurately evaluate the various properties of the solid. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for measuring the bulk density of solids, aiming to solve the technical problem that during the density measurement process of the gas displacement method and the liquid displacement method in the prior art, the liquid or gas medium will penetrate into the internal pores and closed external pores, resulting in inaccurate measurement.

[0005] The first aspect of the present invention is to provide a method for measuring the bulk density of solids, and the method includes:

[0006] Measure the inner diameter of the first measuring container, and add a measuring medium with a preset particle size to the first measuring container through a funnel;

[0007] Place a pressure piston on the measuring medium, apply pressure with a weight of a preset mass for a preset time, and measure the first height of the measuring medium;

[0008] Weigh the solid to be measured to obtain the solid mass;

[0009] Move a part of the measuring medium through the funnel into the second measuring container, place the solid to be measured on the part of the measuring medium, and then add another part of the measuring medium in the first measuring container into the second measuring container through the funnel to completely cover the solid to be measured, obtaining a mixed solid;

[0010] Place a pressure piston on the mixed solid, apply pressure with a weight of a preset mass for a preset time, and measure the second height of the mixed solid;

[0011] Based on the inner diameter, the solid mass, the first height, and the second height, calculate the packing density of the solid to be measured. The calculation formula is as follows:

[0012]

[0013] Where ρ is the packing density of the solid to be measured, D is the inner diameter of the first measuring container, h1 is the first height, h2 is the second height, and m is the solid mass.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the method for measuring the packing density of a solid provided by the present invention, the accuracy of the test can be effectively improved. Specifically, by selecting a measuring medium with a preset particle size, the part of the measuring medium cannot fill into the inner holes and closed outer holes of the solid to be measured, but can fill into the open outer holes. Then, by measuring the height difference before and after adding the solid to be measured and the inner diameter of the first measuring container under a pressurized state, the packing volume is calculated, and thus the packing density is obtained according to the mass of the solid to be measured, effectively improving the measurement accuracy. Moreover, under the pressurized state, it can ensure that the measuring media are closely fitted to each other and the measuring media are closely fitted to the solid to be measured, improving the packing effect and the measurement accuracy, thereby solving the technical problem that in the process of measuring density by the gas displacement method and the liquid drainage method, the liquid or gas medium will penetrate into the inner holes and closed outer holes, resulting in inaccurate measurement.

[0015] According to one aspect of the above technical solution, the pore categories of the solid to be measured include inner holes, closed outer holes, and open outer holes. By selecting the preset particle size of the measuring medium, it is possible to control the measuring medium not to enter the closed outer holes of the solid to be measured.

[0016] According to one aspect of the above technical solution, the step of placing the solid to be measured on the part of the measuring medium, and then adding another part of the measuring medium in the first measuring container into the second measuring container through the funnel to completely cover the solid to be measured, obtaining a mixed solid, specifically includes:

[0017] By selecting the preset particle size of the measurement medium, gently place the solid to be measured on a part of the measurement medium, and then add another part of the measurement medium in the first measurement container into the second measurement container through the funnel to completely cover the solid to be measured, so that the other part of the measurement medium cannot fill into the inner hole and the closed outer hole, but can fill into the open outer hole, obtaining a mixed solid.

[0018] According to one aspect of the above technical solution, the measurement medium is silica microspheres, and the preset particle size is 10 μm - 200 μm.

[0019] According to one aspect of the above technical solution, the preset mass of the weight is 100 g - 10,000 g, and the preset time is 5 s - 30 s.

[0020] According to one aspect of the above technical solution, the surface roughness of the funnel is 1.6 μm, and the diameter of the funnel is 40 - 80 times the preset particle size of the measurement medium.

[0021] According to one aspect of the above technical solution, the measuring instruments for the inner diameter, the first height, and the second height are vernier calipers.

[0022] According to one aspect of the above technical solution, both the first measurement container and the second measurement container are made of hard glass, and the accuracy grade of the flatness of their bottom surfaces is above grade 8.

[0023] According to one aspect of the above technical solution, the pressure piston includes a first piston part, a second piston part, and a piston rod that movably connects the first piston part and the second piston part. The first piston part is used to carry the weight, and the second piston part is used to fit with the measurement medium to pressurize the measurement medium.

[0024] According to one aspect of the above technical solution, the connection methods of the first piston part, the second piston part, and the piston rod are thread meshing connections. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0026] Figure 1 is a flowchart of the method for measuring the packing density of a solid in the present invention;

[0027] Figure 2 is a schematic diagram of the principle of the method for measuring the packing density of a solid in the present invention;

[0028] Figure 3 is a schematic diagram of the solid to be measured in the present invention;

[0029] Figure 4 Microscopic magnified view of the measurement medium in the embodiment of the present invention;

[0030] Figure 5 Laser particle size distribution diagram of the measurement medium in the embodiment of the present invention. Detailed implementation manners

[0031] To make the objectives, features and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention with reference to the accompanying drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0032] Please refer to Figure 1 - Figure 2 , which shows a method for measuring the packing density of a solid provided by the present invention. The method includes: step S10 - step S15,

[0033] Step S10, measure the inner diameter of the first measuring container, and add a measurement medium with a preset particle size to the first measuring container through a funnel;

[0034] Among them, both the first measuring container and the second measuring container are made of hard glass, and the accuracy grade of the flatness of their bottom surfaces is above grade 8.

[0035] By way of example rather than limitation, for example, the first measuring container and the second measuring container can be graduated cylinders, the inner diameter of which is 10 mm - 100 mm, the height of the first measuring container and the second measuring container can be 100 mm - 300 mm, and the solid volume measurement range is 0.01 cm 3 -1000 cm 3 . For example, if the bottom diameter is 30 mm, the flatness tolerance of grade eight accuracy is about 0.039 mm.

[0036] Step S11, place a pressure piston on the measurement medium, apply pressure with a weight of a preset mass for a preset time, and measure the first height of the measurement medium;

[0037] Among them, pressure is applied to the pressure piston through the weight to ensure that the measurement media are in close contact with each other and the measurement media are in close contact with the solid to be measured, improve the packing effect, and improve the accuracy of the measurement.

[0038] Furthermore, the preset mass of the weight is 100 g - 10000 g, and the preset time is 5 s - 30 s. Specific selection can be made reasonably according to the measurement medium and the solid to be measured.

[0039] Furthermore, the pressurizing piston includes a first piston portion, a second piston portion, and a piston rod movably connecting the first piston portion and the second piston portion. The first piston portion is used to carry weights, and the second piston portion is used to fit with the measurement medium to pressurize the measurement medium. Among them, the outer diameter of the second piston portion matches the inner diameter of the first measurement container, and the fit tolerance is f7 / H8. The flatness accuracy grade of the fitting surface between the second piston portion and the measurement medium also needs to be above grade 8, so that the force is uniform, thereby improving the uniformity of pressing and further improving the accuracy of subsequent measurements.

[0040] Furthermore, the connection manner between the first piston portion, the second piston portion and the piston rod is a threaded meshing connection.

[0041] By way of example rather than limitation, for example, external threads can be provided at both ends of the piston rod, and internal threads are provided on the sides of the first piston portion and the second piston portion close to the piston rod. The internal threads and the external threads are threadedly meshed to achieve movable connection, and the second piston portion can be disassembled and replaced to adapt to different first measurement containers.

[0042] Step S12, weigh the solid to be measured to obtain the solid mass;

[0043] Among them, a balance is used to weigh the solid to be measured.

[0044] Step S13, move part of the measurement medium into the second measurement container through the funnel, place the solid to be measured on the part of the measurement medium, and then add another part of the measurement medium in the first measurement container into the second measurement container through the funnel to completely cover the solid to be measured, obtaining a mixed solid;

[0045] Table 1 Definition and description of the volume of irregular solids

[0046]

[0047]

[0048] As shown in Table 1, the pore categories of the solid to be measured include internal pores, closed external pores, and open external pores. By selecting the preset particle size of the measurement medium, it is possible to control the measurement medium from entering the closed external pores of the solid to be measured. In addition, the solid to be measured can be picked up and placed with tools such as tweezers. For example, as Figure 3 shown, hole A represents a closed external pore, a is the pore diameter of the closed external pore, and hole B is an internal pore.

[0049] Therefore, the pore diameter of the closed external pore can be measured first, and then the preset particle size of the measurement medium can be selected according to the pore diameter.

[0050] Specifically, by selecting the preset particle size of the measurement medium, gently place the solid to be measured on a part of the measurement medium, and then add another part of the measurement medium in the first measurement container into the second measurement container through the funnel to completely cover the solid to be measured, so that the other part of the measurement medium cannot fill into the inner holes and the closed outer holes, but can fill into the open outer holes, obtaining a mixed solid, and then the wrapping volume can be measured, thereby obtaining the wrapping density, avoiding the problem that in the measurement process of the gas displacement method and the liquid drainage method, liquid or gas medium will seep into the inner holes and the closed outer holes, resulting in inaccurate measurement.

[0051] Further, the measurement medium is silica microspheres, and the preset particle size is 10 μm - 200 μm. The silica microspheres have the following characteristics: good fluidity; small particle size; small particle size distribution range; high stiffness and not easy to deform; not easy to absorb moisture and insoluble in water; non-toxic and harmless; chemically stable; not easy to generate static electricity; inexpensive and recyclable multiple times, which is very suitable for measuring the wrapping volume of the solid to be measured and has a good wrapping effect on the solid to be measured.

[0052] Compared with liquid media and gas media, silica microspheres can be reused, the measurement of the wrapping density can be artificially controlled, and it is applicable to the performance measurement of various solids to be measured.

[0053] In addition, the surface roughness of the funnel is 1.6 μm, and the caliber of the funnel is 40 - 80 times the preset particle size of the measurement medium. If the surface roughness of the funnel is large, it will cause the residue of the measurement medium, so that a small part of the measurement medium cannot be added into the first measurement container, affecting the accuracy of the measurement result.

[0054] At the same time, the caliber size of the funnel should match the preset particle size of the measurement medium. If it is too small, it will cause the measurement medium to bridge and cannot smoothly fall into the first measurement container, and cannot evenly cover the solid to be measured. If it is too large, it will cause the measurement medium to fall too fast, with poor wrapping property for the solid to be measured, affecting the measurement result.

[0055] Step S14, place a pressure piston on the mixed solid, apply pressure with a weight of a preset mass for a preset time, and measure the second height of the mixed solid;

[0056] Among them, the measuring instruments for the inner diameter, the first height, and the second height are vernier calipers, replacing the traditional visual reading, and the measurement accuracy is greatly improved.

[0057] In addition, the pressure generated by the weight of the weight and the pressure piston makes the measurement media and between the measurement medium and the solid to be measured in close contact, reducing the void volume and improving the measurement accuracy.

[0058] Step S15: Calculate the wrapping density of the solid to be measured based on the inner diameter, the solid mass, the first height, and the second height. The calculation formula is as follows:

[0059]

[0060] Where ρ is the wrapping density of the solid to be measured, D is the inner diameter of the first measuring container, h1 is the first height, h2 is the second height, and m is the solid mass.

[0061] The present invention will be further described below with specific embodiments:

[0062] An embodiment of the present invention provides a method for measuring the wrapping density of a solid. The method includes: Step S10 - Step S15,

[0063] Step S10: Measure the inner diameter of the first measuring container, and add a measuring medium with a preset particle size to the first measuring container through a funnel;

[0064] Where the closed external pores of the solid to be measured are measured as: a ≤ 18 μm. The first measuring container and the second measuring container are 50 ml graduated cylinders with an inner diameter of 20.7 mm, and the height of the first measuring container and the second measuring container is 198 mm.

[0065] Step S11: Place a pressure piston on the measuring medium, apply pressure with a weight of a preset mass for a preset time, and measure the first height of the measuring medium;

[0066] Where the preset mass of the weight is 1000 g, and the preset time is 5 s.

[0067] Further, the pressure piston includes a first piston portion, a second piston portion, and a piston rod that movably connects the first piston portion and the second piston portion. The first piston portion is used to carry the weight, and the second piston portion is used to fit with the measuring medium to apply pressure to the measuring medium. Where the outer diameter of the second piston portion matches the inner diameter of the first measuring container, and the fit tolerance is f7 / H8. The flatness accuracy grade of the fitting surface between the second piston portion and the measuring medium also needs to be above grade 8. The diameter of the fitting surface between the second piston portion and the measuring medium is 20.70 mm, with a tolerance of -0.020 mm - -0.041 mm, and the height of the second piston portion is 200 mm.

[0068] Step S12: Weigh the solid to be measured to obtain the solid mass;

[0069] Where a balance is used to weigh the solid to be measured, and the balance range is 220 g with an accuracy of 1 mg.

[0070] Step S13: Move part of the measurement medium into the second measurement container through the funnel, place the solid to be measured on the part of the measurement medium, and then add another part of the measurement medium in the first measurement container into the second measurement container through the funnel to completely cover the solid to be measured, obtaining a mixed solid.

[0071] The measurement medium is silica microspheres with a preset particle size of 45 μm and a bulk density of 1.18 g / cm 3 , with a total mass of 300 g and a total bulk volume of 254 cm 3 , an angle of repose of approximately 35°, and a white powder.

[0072] As Figure 4 shown, the silica microspheres are spherical. Compared with the shapes of other solid media, the spherical medium has the best fluidity. As Figure 5 shown, a laser particle size distribution analyzer is used to measure the particle size of the silica microspheres. The particle size of the silica microspheres approximates a normal distribution, with the particle size concentrated between 10 μm and 100 μm, a mean value of 43.92 μm, a small particle size, a small distribution range, and uniform particle sizes, making it an ideal measurement medium.

[0073] In addition, the surface roughness of the funnel is 1.6 μm, and the diameter of the funnel is 2 mm.

[0074] Step S14: Place a pressure piston on the mixed solid, apply pressure with a weight of a preset mass for a preset time, and measure the second height of the mixed solid.

[0075] Among them, the measuring instruments for the inner diameter, the first height, and the second height are vernier calipers with a measuring range of 300 mm and an accuracy of 0.01 mm.

[0076] Step S15: Based on the inner diameter, the solid mass, the first height, and the second height, calculate the packing density of the solid to be measured. The calculation formula is as follows:

[0077] 4m

[0078] ρ = πD 2 (h2 - h1)

[0079] Among them, ρ is the packing density of the solid to be measured, D is the inner diameter of the first measurement container, h1 is the first height, h2 is the second height, and m is the solid mass.

[0080] In this embodiment, according to the specifications of the measuring tools, three 10-mm shallow convex tablets pressed by a tablet press are used as the solids to be measured. The measurement results are as follows: the mass of the solid to be measured is 1.370 g, the first height is 244.74 mm, and the second height is 247.83 mm. Then the packing density of the solid is:

[0081]

[0082] The theoretical wrapping density calculated from the regular tablets is as follows:

[0083]

[0084] The error between the actual measurement result and the theoretical calculation is as follows:

[0085]

[0086] From the test results, the error between the actual measurement result and the theoretical calculated value does not exceed 5%. The measurement effect is accurate, with high reliability and stability. The method structure device of this embodiment is simple, with low cost, easy to promote and use, can measure various soluble solids, has a wide application range, and provides an important and reliable measurement method for the measurement of the wrapping density of various solids in actual production.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0088] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A method for measuring the packing density of a solid, characterized in that: The method comprises: Measuring the inner diameter of the first measuring container, and adding the measuring medium with a preset particle size into the first measuring container through a funnel; Placing a pressurizing piston on the measuring medium, applying pressure with a weight of a preset mass for a preset time, and measuring a first height of the measuring medium; Weigh the solid to be tested to obtain the mass of the solid; Moving part of the measuring medium to the second measuring container through the funnel, placing the solid to be measured on the part of the measuring medium, and then adding another part of the measuring medium in the first measuring container to the second measuring container through the funnel to completely cover the solid to be measured, to obtain a mixed solid; placing a pressurizing piston on the mixed solid, applying pressure with a weight of a preset mass for a preset time, and measuring a second height of the mixed solid; Based on the inner diameter, the solid mass, the first height and the second height, the package density of the solid to be measured is calculated, and the calculation formula is as follows: Wherein, ρ is the packing density of the solid to be measured, D is the inner diameter of the first measuring container, h1 is the first height, h2 is the second height, and m is the mass of the solid.

2. The method for measuring the packing density of a solid according to claim 1, characterized in that: The pore types of the solid to be measured include inner pores, closed outer pores and open outer pores. By selecting a preset particle size of the measuring medium, the measuring medium can be controlled not to enter the closed outer pores of the solid to be measured.

3. The method for measuring the packing density of a solid according to claim 2, characterized in that: The step of placing the solid to be measured on the part of the measuring medium, and then adding another part of the measuring medium in the first measuring container into the second measuring container through the funnel to completely cover the solid to be measured to obtain a mixed solid specifically includes: By selecting the preset particle size of the measuring medium, the solid to be measured is gently placed on the part of the measuring medium, and then another part of the measuring medium in the first measuring container is added to the second measuring container through the funnel to completely cover the solid to be measured, so that the other part of the measuring medium cannot be filled into the inner hole and the closed outer hole, but can be filled into the open outer hole to obtain a mixed solid.

4. The method for measuring the packing density of a solid according to claim 3, characterized in that: The measuring medium is silicon dioxide microspheres, and the preset particle size is 10 μm-200 μm.

5. The method for measuring the packing density of a solid according to claim 1, characterized in that: The preset mass of the weight is 100g-10000g, and the preset time is 5s-30s.

6. The method for measuring the packing density of a solid according to claim 5, characterized in that: The surface roughness of the funnel is 1.6 μm, and the caliber of the funnel is 40-80 times the preset particle size of the measuring medium.

7. The method for measuring the packing density of a solid according to claim 1, characterized in that: The measuring instrument for the inner diameter, the first height and the second height is a vernier caliper.

8. The method for measuring the packing density of a solid according to claim 1, characterized in that: The first measuring container and the second measuring container are both made of hard glass, and the accuracy level of the bottom surface flatness is above level 8.

9. The method for measuring the packing density of a solid according to claim 1, characterized in that: The pressurizing piston includes a first piston part, a second piston part, and a piston rod movably connecting the first piston part and the second piston part. The first piston part is used to carry a weight, and the second piston part is used to fit the measuring medium to pressurize the measuring medium.

10. The method for measuring the packing density of a solid according to claim 9, characterized in that: The first piston part, the second piston part and the piston rod are connected by threaded engagement.

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