CN114965155B

CN114965155B - A device and test method for measuring the apparent density of powder materials based on exhaust method

Info

Publication number: CN114965155B
Application number: CN202210404058.7A
Authority: CN
Inventors: 张辉; 刘凯迪; 回朝妍; 徐毓涵; 袁军杰; 晏娟婷; 汪一帆
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2022-04-18
Filing date: 2022-04-18
Publication date: 2024-11-22
Anticipated expiration: 2042-04-18
Also published as: CN114965155A

Abstract

The present invention provides a device and a testing method for determining the apparent density of powder materials based on an exhaust method, and belongs to the technical field of material density determination. The device includes a gas filtration and guiding system, a gas temperature stabilization and measurement system, an upper end cover sealing and fastening system, an air path chamber integrated module, a lower end cover sealing and fastening system, an absolute pressure sensor and a sample cup; the upper end cover sealing and fastening system, the air path chamber integrated module, the lower end cover sealing and fastening system and the gas filtration and guiding system constitute a pipeline-free gas sealing system. When used, firstly, two dense solid blocks of known and different volumes are used to calibrate the sample chamber volume and the reference chamber volume in the air path chamber integrated module, and then the absolute pressure and temperature of the gas in each step are respectively measured by a pressure sensor and a temperature sensor, and the volume of the powder material is calculated according to the law of conservation of mass, and finally the apparent density of the powder material is calculated according to the mass of the powder material. The device can realize full automation of the testing process.

Description

Device and test method for measuring apparent density of powder material based on exhaust method

Technical Field

The invention relates to the technical field of material density measurement, in particular to a device and a test method for measuring apparent density of a powder material based on an exhaust method.

Background

The apparent volume is the sum of the volume occupied by the solid framework part of the material and the volume occupied by the closed pore, the apparent density is the ratio of the mass of the material to the apparent volume, and the traditional measuring method of the apparent density is a liquid discharge method. This approach has a number of disadvantages: materials that react or are compatible with liquids cannot be measured; the tested material is easy to damage; the waste liquid is generated more; because the liquid has surface tension, the liquid is difficult to enter into gaps formed among particles of the powder material and micropore channels in the porous material, so that the volume of the discharged liquid is increased, and the measured value is smaller.

The degassing method is a nondestructive measurement method using inert gas instead of liquid. The gas molecules enter the gaps among the particles of the material and the open pore channels in the material, so that the open framework volume can be calculated, and the measurement accuracy is improved. However, the following problems are mainly involved in measuring apparent density of powder materials by using an exhaust method:

(1) Air passage blockage

The powder material is mostly light components, in the measurement process, high-pressure gas enters into the material formed by stacking the powder material, in the pressure equalizing stage, the gas is released from the material by the rapidly reduced pressure, the powder material is also stacked at a narrow gas path or a valve along with the gas flow to cause gas path blockage, the measured value is slowly increased, and the measurement accuracy is reduced.

(2) Valve inner leakage

When powder material enters the sealing point of the valve along with the air flow, powder can be deposited at the sealing gasket due to the narrowing of the air passage, so that the valve cannot be sealed, and in the pressure equalizing stage, the air can flow out through the valve to form an internal leakage phenomenon. The more powder accumulates, the worse the valve tightness, the more severe the internal leakage, resulting in smaller measurements.

(3) Gas leakage

The exhaust method uses inert gas as a measuring working medium, a pressure sensor, a pipeline joint, a switch valve and the like are usually connected with a sample cavity and a reference cavity by threads, and under the condition of relatively high pressure, the gas is easy to leak out from the threads, so that the mass conservation in the measuring process is difficult to ensure.

(4) Uneven air temperature

The gas source is mostly a high-pressure gas steel cylinder, the temperature of the gas source is greatly influenced by the storage position, the gas flows through pipelines of different materials and temperature fields from the gas source to a measuring point, and the temperature change of the gas is large; in the measuring process, the temperature of the test gas is difficult to be at the same temperature due to the length, thickness and other reasons of the connecting pipeline, the temperature of each part of the gas is uneven, and meanwhile, the actual temperature of the gas cannot be measured rapidly and accurately due to the fact that the gas is in a closed space.

(5) Pressure fluctuation

The air source pressure is difficult to control due to different operation of a tester, the air source pressure is continuously reduced along with the increase of the service time, the external environment pressure is greatly changed along with the factors such as seasons, day and night, weather and the like, the absolute pressure adopted in the testing process correspondingly fluctuates, and the pressure change can influence the measurement result because the air is a compressible medium.

The adoption of the gas circuit chamber integrated module and the seat-mounted electromagnetic valve can reduce the dead volume and the air leakage point of the connecting pipeline, and the sealing gasket replaces threads, so that the air tightness can be improved. The filter element is arranged inside the valve, so that powder materials can be prevented from entering the gas path and the valve along with the gas flow. When calibrating, the large-volume solid block and the small-volume solid block with known volumes are used as calibrators, the large-volume coefficients of the large-volume solid block under different air inlet pressures are measured to form a reference table, when calibrating by a user, only the small-volume coefficients corresponding to the small-volume solid block under a certain air inlet pressure are measured, the large-volume coefficients corresponding to the large-volume solid block under the same air inlet pressure are obtained through interpolation operation, and the volumes of the sample cavity and the reference cavity are further calculated. And a temperature sensor is arranged in the exhaust port channel, the temperature of the gas in different stages is directly measured, and a calculation formula is corrected. And during measurement, calculating the maximum deviation value of the known time period according to the accuracy and the measuring range of the pressure sensor, fitting a pressure change curve in the data acquisition time period by using a least square method, comparing the maximum deviation value of the known time period with the slope of the curve, and identifying the airtight characteristics of the air inlet valve, the pressure equalizing valve and the air outlet valve. Therefore, a device and a testing method for measuring the apparent density of the powder material based on an exhaust method are specially designed.

Disclosure of Invention

The invention provides a device and a test method for measuring apparent density of a powder material based on an exhaust method, which are used for solving the problems of air channel blockage and valve internal leakage caused by powder blowing in the apparent density measurement process of the powder material and the problems of gas leakage, uneven air temperature and pressure fluctuation in the test process.

The device comprises a gas filtering and guiding system, a gas temperature stabilizing and measuring system, an upper end cover sealing and fastening system, a gas circuit chamber integrated module, a lower end cover sealing and fastening system, an absolute pressure sensor and a sample cup;

Wherein the gas filtering and guiding system comprises an air inlet valve, a pressure equalizing valve, an air outlet valve, a top filter screen, a filter element, a bottom filter screen, an upper O-shaped ring and a lower O-shaped ring,

The air inlet valve comprises an air inlet valve inlet, an air inlet valve outlet, an air inlet valve right through hole and an air inlet valve left through hole, an air inlet valve inlet sealing gasket is arranged at the air inlet valve inlet, an air inlet valve outlet sealing gasket is arranged at the air inlet valve outlet, the air inlet valve inlet and the air inlet valve outlet are arranged up and down, and the air inlet valve right through hole and the air inlet valve left through hole are horizontally arranged between the air inlet valve inlet and the air inlet valve outlet;

The structure of the equalizing valve and the structure of the exhaust valve are the same as those of the air inlet valve, the equalizing valve comprises an equalizing valve inlet, an equalizing valve outlet, an equalizing valve right through hole and an equalizing valve left through hole, an equalizing valve inlet sealing gasket is arranged at the equalizing valve inlet, and an equalizing valve outlet sealing gasket is arranged at the equalizing valve outlet; the exhaust valve comprises an exhaust valve inlet, an exhaust valve outlet, an exhaust valve right through hole and an exhaust valve left through hole, wherein the exhaust valve inlet is provided with an exhaust valve inlet sealing gasket, and the exhaust valve outlet is provided with an exhaust valve outlet sealing gasket;

The gas temperature stabilizing and measuring system comprises an inverted cone joint, a clamping sleeve, a capillary red copper spiral tube and a temperature sensor, wherein one end of the capillary red copper spiral tube is a capillary red copper spiral tube outlet, and the other end is a capillary red copper spiral tube inlet;

the upper end cover sealing fastening system comprises a spiral cover, an upper end cover sealing blind plate, a rear pin, an upper end cover O-shaped ring and a front pin, wherein the inner wall of the spiral cover is provided with a spiral cover internal thread, a front pin hole and a rear pin hole are vertically formed in the symmetrical position of the upper end cover sealing blind plate ring, and the inner wall of the upper end cover sealing blind plate ring is provided with an upper end cover O-shaped ring sealing groove;

The lower end cover sealing fastening system comprises a lower end cover sealing blind plate, a lower end cover rear sealing bolt, a lower end cover left sealing bolt, a lower end cover right sealing bolt, a lower end cover front fastening bolt, a lower end cover O-shaped ring, a lower end cover right fastening bolt and a lower end cover left fastening bolt, wherein the annular inner wall of the lower end cover sealing blind plate is provided with a lower end cover O-shaped ring sealing groove, the lower end cover O-shaped ring is arranged in the lower end cover O-shaped ring sealing groove, the lower surface of the lower end cover sealing blind plate is provided with a through lower end cover rear sealing through hole, a lower end cover left sealing through hole and a lower end cover right sealing through hole, and the upper surface of the lower end cover sealing blind plate is provided with a through lower end cover left fastening through hole, a lower end cover front fastening through hole and a lower end cover right fastening through hole;

The gas circuit chamber integrated module comprises a sample cavity, a filtering hole and a reference cavity, wherein the sample cavity is positioned at the upper part of the gas circuit chamber integrated module, the sample cavity is enclosed by an upper end cover sealing blind plate, an upper end cover O-shaped ring, a pressure taking hole, a sample cavity inlet and a sample cavity outlet to form a sealing cavity, a sample cup is arranged in the sample cavity, the lower part of the sample cavity is provided with the filtering hole, the reference cavity is positioned at the lower part of the gas circuit chamber integrated module, and the reference cavity is enclosed by a reference cavity inlet, a reference cavity outlet, a lower end cover O-shaped ring and a lower end cover sealing blind plate to form a sealing cavity;

the outer surface of the upper end of the gas circuit chamber integrated module is provided with gas circuit chamber integrated module external sealing threads, the upper end plane of the gas circuit chamber integrated module is vertically provided with a front positioning hole and a rear positioning hole, the lower end plane is vertically provided with a lower end cover rear fastening threaded hole, a lower end cover left fastening threaded hole and a lower end cover right fastening threaded hole, the upper part of the front end plane of the gas circuit chamber integrated module is provided with a sample chamber inlet, a gas inlet valve left threaded hole and a gas inlet valve right threaded hole, the gas inlet is connected with an external gas source interface through a pore channel and a coarse pore channel, the sample chamber inlet is connected with the sample chamber through the pore channel, the middle part of the front end plane of the gas circuit chamber integrated module is provided with a sample chamber outlet, a reference chamber inlet, a pressure equalizing valve left threaded hole and a pressure equalizing valve right threaded hole, the sample chamber outlet is connected with a filter hole through the pore channel, the filter hole is connected with the lower part of the sample chamber through the pore channel, the reference chamber inlet is connected with the reference chamber through the pore channel, the reference chamber outlet, the vent valve left threaded hole and the vent valve right threaded hole are arranged below the plane of the gas circuit chamber integrated module.

The air inlet valve is aligned with the air inlet, the air inlet valve outlet is aligned with the sample cavity inlet, the fastening screw is screwed into the air inlet valve right threaded hole through the air inlet valve right through hole, the fastening screw is screwed into the air inlet valve left threaded hole through the air inlet valve left through hole, and after the fastening screw is screwed, the air inlet valve is sealed with the air circuit cavity integrated module through the air inlet valve inlet sealing gasket and the air inlet valve outlet sealing gasket;

the pressure equalizing valve inlet is aligned with the sample cavity outlet, the pressure equalizing valve outlet is aligned with the reference cavity inlet, the fastening screw is screwed into the pressure equalizing valve right threaded hole through the pressure equalizing valve right through hole, the fastening screw is screwed into the pressure equalizing valve left threaded hole through the pressure equalizing valve left through hole, and after the fastening screw is screwed, the pressure equalizing valve is sealed with the gas circuit cavity integrated module through the pressure equalizing valve inlet sealing gasket and the pressure equalizing valve outlet sealing gasket;

The exhaust valve inlet is aligned with the reference cavity outlet, the exhaust valve outlet is aligned with the exhaust port, the fastening screw is screwed into the right threaded hole of the exhaust valve through the right through hole of the exhaust valve, the fastening screw is screwed into the left threaded hole of the exhaust valve through the left through hole of the exhaust valve, and after the fastening screw is screwed, the exhaust valve is sealed with the gas circuit cavity integrated module through the sealing gasket of the exhaust valve inlet and the sealing gasket of the exhaust valve outlet.

The top filter screen is folded and coated at the upper end of the filter element, the top filter screen after being tightly folded by the upper end O-shaped ring is arranged in the upper end O-shaped ring sealing groove, the bottom filter screen is folded and coated at the lower end of the filter element, the bottom filter screen after being tightly folded by the lower end O-shaped ring is arranged in the lower end O-shaped ring sealing groove, a filter assembly is formed, the filter assembly is arranged in the filter hole, the upper end O-shaped ring and the lower end O-shaped ring are matched with the filter hole, and powder materials are filtered.

The inlet of the capillary red copper spiral pipe is connected with an external air source, the outlet of the capillary red copper spiral pipe sequentially penetrates through the back taper joint and the cutting sleeve, the back taper joint is arranged in a hole corresponding to the external air source interface, the back taper joint is connected with the external air source interface through fastening threads, the cutting sleeve is made of soft materials, the radial surface of the cutting sleeve is extruded to form sealing with the periphery of a channel in the screwing process of the back taper joint, and the temperature sensor is arranged in the gas temperature measuring channel.

The front pin is connected with the front pin hole through threads, the rear pin is connected with the rear pin hole through threads, the O-shaped ring of the upper end cover is arranged in the O-shaped ring sealing groove of the upper end cover, the front pin is arranged in the front positioning hole, and the rear pin is arranged in the rear positioning hole;

The spiral cover is arranged above the upper end cover sealing blind plate, the spiral cover is rotated clockwise to press the upper end cover sealing blind plate, and the upper end cover sealing blind plate forms sealing with the gas circuit chamber integrated module through an upper end cover O-shaped ring.

The lower end cover rear sealing bolt penetrates through the lower end cover rear sealing through hole from bottom to top, is screwed into the lower end cover rear fastening threaded hole, the lower end cover left sealing bolt penetrates through the lower end cover left sealing through hole from bottom to top, is screwed into the lower end cover left fastening threaded hole, the lower end cover right sealing bolt penetrates through the lower end cover right sealing through hole from bottom to top, is screwed into the lower end cover right fastening threaded hole, and compresses the lower end cover O-shaped ring at the bottom end of the gas circuit chamber integrated module through the lower end cover sealing blind plate by the lower end cover rear sealing bolt, the lower end cover left sealing bolt and the lower end cover right sealing bolt to form sealing for the reference cavity;

the front fastening bolt of the lower end cover, the right fastening bolt of the lower end cover and the left fastening bolt of the lower end cover respectively pass through the front fastening through hole of the lower end cover, the right fastening through hole of the lower end cover and the left fastening through hole of the lower end cover from top to bottom to be connected with corresponding threads on the lower end stable fixture, so as to fix the device.

The absolute pressure sensor is connected with the gas circuit chamber integrated module at the pressure taking hole through threads.

The gas circuit chamber integrated module is made of nonmetallic materials with small heat conductivity, so that the heat dissipation of gas can be reduced, the gas temperature is stabilized, and the gas circuit chamber integrated module is organic glass with the heat conductivity of 0.14W/(m.K) to 0.2W/(m.K).

The air inlet valve, the equalizing valve and the air outlet valve are all seat-mounted electromagnetic valves and are sealed with a smooth plane through sealing gaskets.

The application method of the device comprises the following steps:

s1: measurement of the large volume coefficient under different intake pressures: the measurement of the coefficient of large volume (the volume is 5-15 mL) under different air inlet pressures means that the air inlet pressure is changed every 5kPa between 130kPa and 230kPa, and the corresponding volume coefficient of a known large-volume compact solid block is measured; the method comprises the following steps:

placing a sample cup in a sample cavity, placing a large-volume compact solid block with a known volume in the sample cup, aligning a rear pin and a front pin of a sealing blind plate of an upper end cover with a rear positioning hole and a front positioning hole of a gas circuit chamber integrated module respectively, and screwing down a screw cap clockwise;

the large volume coefficient measurement comprises three stages of exhaust, air intake and pressure equalizing,

In the exhaust stage, the external air source pressure is regulated to enable the absolute air inlet pressure to reach 130kPa, an air inlet valve, an equalizing valve and an exhaust valve are sequentially opened, the air inlet valve is closed after 5 seconds, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

in the air inlet stage, an air inlet valve is opened, temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 seconds as the air inlet temperature, a pressure equalizing valve and an air outlet valve are sequentially closed, the air inlet valve is closed after 30 seconds, pressure data is read after 30 seconds, the air inlet valve is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 seconds as the air inlet pressure;

In the pressure equalizing stage, the pressure equalizing valve is opened, pressure data are read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 times within 2 seconds as pressure equalizing pressure, the exhaust valve is opened, temperature data are read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 times within 2 seconds as pressure equalizing temperature;

according to the law of conservation of mass, the mole number of gas in a free space when the large-volume compact solid block is placed in the sample cavity in the air inlet stage is equal to the mole number of gas in the free space when the large-volume compact solid block is placed in the sample cavity in the pressure equalizing stage and the free space of the reference cavity, and the ratio of the free space volume when the large-volume compact solid block is placed in the sample cavity to the free space volume of the reference cavity is calculated, namely the large volume coefficient when the air inlet pressure is 130 kPa;

Raising the air inlet pressure to 135kPa, continuing to exhaust, air inlet and pressure equalizing to obtain a large volume coefficient when the air inlet pressure is 135kPa, and continuing to sequentially raise the pressure by 5kPa until the large volume coefficient when the air inlet pressure is 230kPa is obtained to form a large volume coefficient reference table under different air inlet pressures;

S2: measurement of the coefficient of small volume (volume of 2 mL-5 mL) at constant intake pressure: according to the material pressure requirement, determining that the air inlet pressure is a constant value P1; placing a sample cup in a sample cavity, placing a small-volume compact solid block with a known volume in the sample cup, aligning a rear pin and a front pin of a sealing blind plate of an upper end cover with a rear positioning hole and a front positioning hole of a gas circuit chamber integrated module respectively, and screwing down a screw cap clockwise;

The measurement of the small volume coefficient comprises three stages of exhaust, air intake and pressure equalizing,

In the exhaust stage, the pressure of an external air source is regulated to be P1, an air inlet valve, a pressure equalizing valve and an air outlet valve are sequentially opened, the air inlet valve is closed after 5 seconds, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the pressure data and the median value of the temperature data in 20 times are respectively used as back pressure and back temperature;

In the air inlet stage, an air inlet valve is opened, temperature data is read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, the medium value of the 20 times of temperature data is used as air inlet temperature, a pressure equalizing valve and an air outlet valve are sequentially closed, the air inlet valve is closed after 30 seconds, pressure data is read after 30 seconds, once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data is used as air inlet pressure;

According to the law of conservation of mass, the mole number of gas in a free space when the small-volume compact solid block is placed in the sample cavity in the air inlet stage is equal to the mole number of gas in the free space when the small-volume compact solid block is placed in the sample cavity in the pressure equalizing stage and the free space of the reference cavity, and the ratio of the free space volume when the small-volume compact solid block is placed in the sample cavity to the free space volume of the reference cavity is calculated, namely the small volume coefficient when the air inlet pressure is P1;

S3: apparent density measurement of sample at constant inlet pressure: interpolation calculation is carried out on the large volume coefficient corresponding to the constant value P1 of the air inlet pressure in the large volume coefficient reference table under different air inlet pressures, and the free space volume of the reference cavity and the free space volume of the sample cavity when the sample cup is placed in the sample cavity are calculated by combining the small volume coefficient when the air inlet pressure is the constant value P1;

the air inlet pressure is kept to be equal to P1, the screw cap is opened in the anticlockwise direction, a sample cup is taken out, a sample with known mass is weighed, the sample cup with the sample is placed in the sample cavity, the rear pin and the front pin of the upper end cover sealing blind plate are respectively aligned with the rear positioning hole and the front positioning hole of the air circuit cavity integrated module, and the screw cap is screwed down in the clockwise direction;

the apparent density measurement of the sample under constant inlet pressure comprises three stages of exhaust, inlet and pressure equalizing,

In the exhaust stage, an air inlet valve, a pressure equalizing valve and an exhaust valve are sequentially opened, the air inlet valve is closed after 5 seconds, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

According to the law of conservation of mass, the mole number of gas in a free space when a sample is placed in a sample cavity in an air inlet stage is equal to the mole number of gas in a free space when the sample is placed in the sample cavity in a pressure equalizing stage and the reference cavity, the ratio of the free space volume when the sample is placed in the sample cavity to the free space volume of the reference cavity is calculated, the free space volume when the sample is placed in the sample cavity can be calculated by taking the free space volume of the reference cavity as a known quantity, the volume of the sample is calculated by taking the free space volume when a sample cup is placed in the sample cavity, and the apparent density of the sample is calculated according to the mass of the sample.

The technical scheme of the invention has the following beneficial effects:

In the scheme, the gas path chamber integration module integrates a pipeline through which gas flows with a chamber for storing samples, and an external pipeline is replaced by an internal pore canal, so that the length of the pipeline is shortened, the diameter of the pipeline is reduced, and the temperature uniformity of the gas is improved; the seat-mounted electromagnetic valve is adopted, so that the joint positions are reduced, the air leakage points are reduced, the sealing performance of the module is improved, and the air leakage is reduced; the filtering holes are arranged below the gas circuit chamber integrated module sample chamber and are used for placing the filtering components, so that powder materials are effectively prevented from entering the downstream pore channels and the seat-mounted electromagnetic valve parts, and gas circuit blockage and gas internal leakage are avoided; the temperature sensor is arranged in the gas temperature measuring channel, so that the temperature of the gas in three stages of exhaust, air intake and pressure equalizing can be measured, the calculation result is corrected, and the error caused by uneven air temperature is reduced; the large volume coefficient corresponding to a certain constant value of the air inlet pressure is calculated by interpolation in the large volume coefficient reference table under different air inlet pressures, the free space volume of the reference cavity and the free space volume of the sample cavity when the sample cup is placed in the sample cavity are calculated by combining the small volume coefficient when the air inlet pressure is a certain constant value, and the apparent density of the sample to be measured can be measured at one time; the testing process is fully automated.

Drawings

FIG. 1 is an exploded view of the structure of the device for measuring apparent density of powder material based on the exhaust method of the present invention;

FIG. 2 is a schematic perspective view of an integrated module of a gas circuit chamber in the device for measuring apparent density of powder materials based on an exhaust method;

FIG. 3 is a front view of the gas circuit chamber integrated module in the apparatus for determining apparent density of powder material based on the exhaust method of the present invention;

FIG. 4 is a top view of an integrated gas circuit chamber module in the apparatus for determining apparent density of a powder material based on an exhaust method of the present invention;

fig. 5 is a left side view of the gas circuit chamber integrated module in the device for measuring apparent density of powder material based on the exhaust method of the present invention.

Wherein:

100-intake valve, 101-intake valve inlet gasket, 102-intake valve inlet, 103-intake valve outlet gasket, 104-intake valve outlet, 105-intake valve right through-hole, 106-intake valve left through-hole,

107-Pressure equalizing valve, 108-pressure equalizing valve inlet sealing gasket, 109-pressure equalizing valve inlet, 110-pressure equalizing valve outlet sealing gasket, 111-pressure equalizing valve outlet, 112-pressure equalizing valve right through hole, 113-pressure equalizing valve left through hole,

114-Top filter screen, 115-filter core, 116-upper O-ring sealing groove, 117-lower O-ring sealing groove, 118-bottom filter screen, 119-upper O-ring, 120-lower O-ring,

121-Vent valve, 122-vent valve inlet gasket, 123-vent valve inlet, 124-vent valve outlet gasket, 125-vent valve outlet, 126-vent valve right through-hole, 127-vent valve left through-hole,

200-Back taper joint, 201-cutting ferrule, 202-capillary red copper spiral tube, 203-capillary red copper spiral tube outlet, 204-capillary red copper spiral tube inlet, 205-temperature sensor,

300-Screw cap, 301-screw cap internal thread, 302-front pin hole, 303-upper end cap sealing blind plate, 304-upper end cap O-shaped ring sealing groove, 305-rear pin hole, 306-rear pin, 307-upper end cap O-shaped ring, 308-front pin,

400 Gas circuit chamber integrated module, 401 absolute pressure sensor, 402 pressure tap, 403 pressure tap, 404 sample chamber, 405 filter hole, 406 reference chamber, 407 lower end cap rear fastening screw hole, 408 lower end cap left fastening screw hole, 409 gas temperature measuring channel, 410 gas outlet, 411 gas outlet left screw hole, 412 gas outlet right screw hole, 413 reference chamber outlet, 414 lower end cap right fastening screw hole, 415 reference chamber inlet, 416 pressure equalizing valve right screw hole, 417 pressure equalizing valve left screw hole, 418 sample chamber outlet, 419 external gas source interface, 420 sample chamber inlet, 421 gas inlet valve left screw hole, 422 gas inlet valve right screw hole, 423 gas inlet, 424 gas circuit chamber integrated module external sealing screw thread, 425 front positioning hole, 426 rear positioning hole, 427 sample cup,

500-Lower end cover sealing blind plates, 501-lower end cover rear sealing through holes, 502-lower end cover O-shaped ring sealing grooves, 503-lower end cover left fastening through holes, 504-lower end cover rear sealing bolts, 505-lower end cover left sealing bolts, 506-lower end cover right sealing bolts, 507-lower end cover left sealing through holes, 508-lower end cover front fastening through holes, 509-lower end cover right sealing through holes, 510-lower end cover right fastening through holes, 511-lower end cover front fastening bolts, 512-lower end cover O-shaped rings, 513-lower end cover right fastening bolts and 514-lower end cover left fastening bolts.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.

The invention provides a device and a test method for measuring apparent density of a powder material based on an exhaust method.

As shown in fig. 1, the apparatus includes a gas filtration and guidance system, a gas temperature stabilization and measurement system, an upper end cap seal fastening system, a gas circuit chamber integration module 400, a lower end cap seal fastening system, an absolute pressure sensor 401 and a sample cup 427,

Wherein the gas filtration and guidance system comprises an air inlet valve 100, a pressure equalizing valve 107, an air outlet valve 121, a top filter screen 114, a filter core 115, a bottom filter screen 118, an upper O-ring 119 and a lower O-ring 120,

The air inlet valve 100 comprises an air inlet valve inlet 102, an air inlet valve outlet 104, an air inlet valve right through hole 105 and an air inlet valve left through hole 106, an air inlet valve inlet sealing gasket 101 is arranged at the air inlet valve inlet 102, an air inlet valve outlet sealing gasket 103 is arranged at the air inlet valve outlet 104, the air inlet valve inlet 102 and the air inlet valve outlet 104 are arranged up and down, and the air inlet valve right through hole 105 and the air inlet valve left through hole 106 are horizontally arranged between the air inlet valve inlet 102 and the air inlet valve outlet 104;

The structure of the equalizing valve 107 and the exhaust valve 121 is the same as that of the air inlet valve 100, the equalizing valve 107 comprises an equalizing valve inlet 109, an equalizing valve outlet 111, an equalizing valve right through hole 112 and an equalizing valve left through hole 113, an equalizing valve inlet sealing gasket 108 is arranged at the equalizing valve inlet 109, and an equalizing valve outlet sealing gasket 110 is arranged at the equalizing valve outlet 111; the exhaust valve 121 includes an exhaust valve inlet 123, an exhaust valve outlet 125, an exhaust valve right through hole 126, and an exhaust valve left through hole 127, the exhaust valve inlet 123 is provided with an exhaust valve inlet gasket 122, and the exhaust valve outlet 125 is provided with an exhaust valve outlet gasket 124;

The gas temperature stabilizing and measuring system comprises an inverted cone joint 200, a clamping sleeve 201, a capillary red copper spiral tube 202 and a temperature sensor 205, wherein one end of the capillary red copper spiral tube 202 is a capillary red copper spiral tube outlet 203, and the other end is a capillary red copper spiral tube inlet 204;

The upper end cover sealing fastening system comprises a spiral cover 300, an upper end cover sealing blind plate 303, a rear pin 306, an upper end cover O-shaped ring 307 and a front pin 308, wherein a spiral cover internal thread 301 is arranged on the inner wall of the spiral cover 300, a front pin hole 302 and a rear pin hole 305 are vertically formed in the circular symmetrical position of the upper end cover sealing blind plate 303, and an upper end cover O-shaped ring sealing groove 304 is formed in the circular inner wall of the upper end cover sealing blind plate 303;

The lower end cover sealing fastening system comprises a lower end cover sealing blind plate 500, a lower end cover rear sealing bolt 504, a lower end cover left sealing bolt 505, a lower end cover right sealing bolt 506, a lower end cover front fastening bolt 511, a lower end cover O-shaped ring 512, a lower end cover right fastening bolt 513 and a lower end cover left fastening bolt 514, wherein the lower end cover O-shaped ring sealing groove 502 is arranged on the annular inner wall of the lower end cover sealing blind plate 500, the lower end cover O-shaped ring 512 is arranged in the lower end cover O-shaped ring sealing groove 502, a lower surface of the lower end cover sealing blind plate 500 is provided with a through lower end cover rear sealing through hole 501, a lower end cover left sealing through hole 507 and a lower end cover right sealing through hole 509, and the upper surface of the lower end cover sealing blind plate 500 is provided with a through lower end cover left fastening through hole 503, a lower end cover front fastening through hole 508 and a lower end cover right fastening through hole 510;

As shown in fig. 2,3, 4 and 5, the gas circuit chamber integrated module 400 includes a sample chamber 404, a filtering hole 405 and a reference chamber 406, the sample chamber 404 is located at the upper part of the gas circuit chamber integrated module 400, the sample chamber 404 is enclosed by an upper end cover sealing blind plate 303, an upper end cover O-ring 307, a pressure taking hole 402, a sample chamber inlet 420 and a sample chamber outlet 418 to form a sealing cavity, a sample cup 427 is placed in the sample chamber 404, the lower part of the sample chamber 404 is the filtering hole 405, the reference chamber 406 is located at the lower part of the gas circuit chamber integrated module 400, and the reference chamber 406 is enclosed by a reference chamber inlet 415, a reference chamber outlet 413, a lower end cover O-ring 512 and a lower end cover sealing blind plate 500 to form a sealing cavity;

The outer surface of the upper end of the gas circuit chamber integrated module 400 is provided with gas circuit chamber integrated module external sealing threads 424, the upper end plane of the gas circuit chamber integrated module 400 is vertically provided with a front positioning hole 425 and a rear positioning hole 426, the lower end plane is vertically provided with a lower end cover rear fastening threaded hole 407, a lower end cover left fastening threaded hole 408 and a lower end cover right fastening threaded hole 414, the upper part of the front end plane of the gas circuit chamber integrated module 400 is provided with a sample cavity inlet 420, a gas inlet 423, a gas inlet left threaded hole 421 and a gas inlet right threaded hole 422, the gas inlet 423 is connected with an external gas source interface 419 through a pore channel and a coarse pore channel, the sample cavity inlet 420 is connected with the sample cavity 404 through the pore channel, the middle part of the front end plane of the gas circuit chamber integrated module 400 is provided with a sample cavity outlet 418, a reference cavity inlet 415, a pressure equalizing valve left threaded hole 417 and a equalizing valve right threaded hole 416, the sample cavity outlet 418 is connected with the filter hole 405 through the pore channel, the filter hole 405 is connected to the lower part of the sample cavity 404 through the pore channel, the reference cavity inlet 415 is connected with the reference cavity 406 through the pore channel, the reference cavity 406 is positioned below the filter hole 405, the lower part of the front end plane of the gas circuit chamber integrated module 400 is provided with a reference cavity outlet 413, the gas outlet 410, the gas outlet and the gas outlet 412 is connected with the gas outlet valve outlet 412 through the pore channel and the gas outlet valve 401 through the pore channel and the pore channel 401.

The intake valve inlet 102 is aligned with the air inlet 423, the intake valve outlet 104 is aligned with the sample chamber inlet 420, the fastening screw is screwed into the intake valve right threaded hole 422 through the intake valve right through hole 105, the fastening screw is screwed into the intake valve left threaded hole 421 through the intake valve left through hole 106, and after the fastening screw is screwed, the intake valve 100 is sealed with the gas circuit chamber integrated module 400 through the intake valve inlet sealing gasket 101 and the intake valve outlet sealing gasket 103;

The equalizing valve inlet 109 is aligned with the sample chamber outlet 418, the equalizing valve outlet 111 is aligned with the reference chamber inlet 415, the fastening screw is screwed into the equalizing valve right threaded hole 416 through the equalizing valve right through hole 112, the fastening screw is screwed into the equalizing valve left threaded hole 417 through the equalizing valve left through hole 113, and after the fastening screw is screwed, the equalizing valve 107 is sealed with the gas circuit chamber integration module 400 through the equalizing valve inlet gasket 108 and the equalizing valve outlet gasket 110;

The vent valve inlet 123 is aligned with the reference chamber outlet 413, the vent valve outlet 125 is aligned with the vent valve 410, the fastening screw is screwed into the vent valve right threaded hole 412 through the vent valve right through hole 126, the fastening screw is screwed into the vent valve left threaded hole 411 through the vent valve left through hole 127, and after the fastening screw is screwed, the vent valve 121 is sealed with the air passage chamber integration module 400 through the vent valve inlet gasket 122 and the vent valve outlet gasket 124.

The top filter screen 114 is folded and coated on the upper end of the filter core 115, the top filter screen 114 after being folded is tightly bound by the upper end O-shaped ring 119 and is placed in the upper end O-shaped ring sealing groove 116, the bottom filter screen 118 is folded and coated on the lower end of the filter core 115, the bottom filter screen 118 after being folded and is tightly bound by the lower end O-shaped ring 120 and is placed in the lower end O-shaped ring sealing groove 117, a filter assembly is formed, the filter assembly is placed in the filter hole 405, and the upper end O-shaped ring 119 and the lower end O-shaped ring 120 are matched with the filter hole 405 to filter powder materials.

The capillary red copper spiral pipe inlet 204 is connected with an external air source, the capillary red copper spiral pipe outlet 203 sequentially penetrates through the back taper joint 200 and the clamping sleeve 201, and is arranged in a hole corresponding to the external air source interface 419, the back taper joint 200 is connected with the external air source interface 419 through fastening threads, the clamping sleeve 201 is soft, and in the screwing process of the back taper joint 200, the radial surface of the clamping sleeve 201 is extruded to form sealing with the periphery of a channel, and the temperature sensor 205 is arranged in the air temperature measuring channel 409.

The front pin 308 is connected with the front pin hole 302 through threads, the rear pin 306 is connected with the rear pin hole 305 through threads, the upper end cover O-shaped ring 307 is arranged in the upper end cover O-shaped ring sealing groove 304, the front pin 308 is arranged in the front positioning hole 425, and the rear pin 306 is arranged in the rear positioning hole 426;

the screw cap 300 is placed above the upper end cap sealing blind plate 303, the screw cap 300 is rotated clockwise to press the upper end cap sealing blind plate 303 tightly, and the upper end cap sealing blind plate 303 forms a seal with the gas circuit chamber integrated module 400 through the upper end cap O-shaped ring 307.

The lower end cover rear sealing bolt 504 passes through the lower end cover rear sealing through hole 501 from bottom to top, is screwed into the lower end cover rear fastening threaded hole 407, the lower end cover left sealing bolt 505 passes through the lower end cover left sealing through hole 507 from bottom to top, is screwed into the lower end cover left fastening threaded hole 408, the lower end cover right sealing bolt 506 passes through the lower end cover right sealing through hole 509 from bottom to top, is screwed into the lower end cover right fastening threaded hole 414, and the lower end cover rear sealing bolt 504, the lower end cover left sealing bolt 505 and the lower end cover right sealing bolt 506 tightly press the lower end cover O-shaped ring 512 at the bottom end of the gas circuit chamber integrated module 400 through the lower end cover sealing blind plate 500 to form a seal for the reference chamber 406;

The lower end cover front fastening bolt 511, the lower end cover right fastening bolt 513 and the lower end cover left fastening bolt 514 respectively pass through the lower end cover front fastening through hole 508, the lower end cover right fastening through hole 510 and the lower end cover left fastening through hole 503 from top to bottom to be connected with corresponding threads on the lower end stabilizing fixture, so as to fix the device.

The absolute pressure sensor 401 is connected to the gas circuit chamber integrated module 400 at the pressure taking hole 402 by threads.

The gas circuit chamber integrated module 400 is made of a nonmetallic material with small heat conductivity.

The intake valve 100, the equalizing valve 107 and the exhaust valve 121 are all seat-mounted solenoid valves and are sealed with a smooth surface by a gasket.

The application method of the device comprises the following steps:

s1: measurement of the large volume coefficient under different intake pressures: the measurement of the large volume coefficient under different air inlet pressures means that the air inlet pressure is changed every 5kPa between 130kPa and 230kPa, and the volume coefficient corresponding to the known large-volume compact solid block is measured; the method comprises the following steps:

Placing a sample cup 427 in the sample cavity 404, placing a large-volume compact solid block with a known volume in the sample cup 427, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the gas circuit chamber integrated module 400 respectively, and screwing the screw cap 300 clockwise;

In the exhaust stage, the external air source pressure is regulated to enable the absolute air inlet pressure to reach 130kPa, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve are sequentially opened for 121,5 seconds, then the air inlet valve 100 is closed, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

In the air intake stage, the air intake valve 100 is opened, temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 seconds as the air intake temperature, the pressure equalizing valve 107 and the air exhaust valve 121 are sequentially closed, the air intake valve 100 is closed after 30 seconds, pressure data is read after 30 seconds, the air intake valve 100 is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 seconds as the air intake pressure;

in the equalizing stage, the equalizing valve 107 is opened, pressure data is read after 30 seconds, the pressure data is read once every 100ms, the median value of the 20 times of pressure data is continuously read for 2 seconds to serve as equalizing pressure, the exhaust valve 121 is opened, temperature data is read once every 100ms, the pressure data is continuously read for 20 times every 2 seconds, and the median value of the 20 times of temperature data is used as equalizing temperature;

According to the law of conservation of mass, the mole number of gas in the free space when the large-volume compact solid block is placed in the sample cavity 404 in the air inlet stage is equal to the mole number of gas in the free space when the large-volume compact solid block is placed in the sample cavity 404 in the pressure equalizing stage and the free space of the reference cavity 406, and the ratio of the free space volume when the large-volume compact solid block is placed in the sample cavity 404 to the free space volume of the reference cavity 406 is calculated, namely, the large volume coefficient when the air inlet pressure is 130 kPa;

S2: small volume coefficient measurement at constant intake pressure: according to the material pressure requirement, determining that the air inlet pressure is a constant value P1; placing a sample cup 427 in the sample cavity 404, placing a small-volume compact solid block with a known volume in the sample cup 427, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the gas circuit chamber integrated module 400 respectively, and screwing the screw cap 300 clockwise;

In the exhaust stage, the external air source pressure is regulated to be P1, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve are sequentially opened for 121,5 seconds, then the air inlet valve 100 is closed, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

In the air intake stage, the air intake valve 100 is opened, the temperature data is read once every 100ms, the temperature data is continuously read for 20 times within 2 seconds, the medium value of the 20 times of the temperature data is used as the air intake temperature, the pressure equalizing valve 107 and the air exhaust valve 121 are sequentially closed, the air intake valve 100 is closed after 30 seconds, the pressure data is read after 30 seconds, the temperature data is read once every 100ms, the pressure data is continuously read for 20 times within 2 seconds, and the medium value of the 20 times of the pressure data is used as the air intake pressure;

According to the law of conservation of mass, the mole number of the gas in the free space when the small-volume compact solid block is placed in the sample cavity 404 in the air inlet stage is equal to the mole number of the gas in the free space when the small-volume compact solid block is placed in the sample cavity 404 in the pressure equalizing stage and the free space of the reference cavity 406, and the ratio of the free space volume when the small-volume compact solid block is placed in the sample cavity 404 to the free space volume of the reference cavity 406 is calculated, namely, the small volume coefficient when the air inlet pressure is P1;

S3: apparent density measurement of sample at constant inlet pressure: interpolation calculation is carried out on the large volume coefficient corresponding to the constant value P1 of the air inlet pressure in the large volume coefficient reference table under different air inlet pressures, and the free space volume of the reference cavity 406 and the free space volume of the sample cavity 404 when the sample cup 427 is placed are calculated by combining the small volume coefficient when the air inlet pressure is the constant value P1;

Keeping the air inlet pressure equal to P1, opening the spiral cover 300 in the anticlockwise direction, taking out the sample cup 427, weighing a sample with known mass, placing the sample cup 427 with the sample in the sample cavity 404, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the air channel cavity integrated module 400 respectively, and screwing the spiral cover 300 in the clockwise direction;

In the exhaust stage, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve 121,5 seconds are sequentially opened, the air inlet valve 100 is closed, pressure and temperature data are read once every 100ms after 30 seconds, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

According to the law of conservation of mass, the number of moles of gas in the free space when the sample is placed in the sample cavity 404 in the air intake stage is equal to the number of moles of gas in the free space when the sample is placed in the sample cavity 404 in the pressure equalizing stage and the reference cavity 406, the ratio of the free space volume when the sample is placed in the sample cavity 404 to the free space volume of the reference cavity 406 is calculated, the free space volume when the sample is placed in the sample cavity 404 can be calculated by taking the free space volume of the reference cavity 406 as a known quantity, the volume of the sample is calculated by taking the free space volume when the sample cup 427 is placed in the sample cavity 404, and the apparent density of the sample is calculated according to the mass of the sample.

In the specific test process, the steps are as follows:

S1: measurement of the large volume coefficient under different intake pressures: the measurement of the large volume coefficient under different air inlet pressures refers to the measurement of the volume coefficient C _130bs、C_135bs、C_140bs、…、C_230bs corresponding to a known large-volume compact solid block by changing the air inlet pressure every 5kPa between 130kPa and 230 kPa; wherein, the large volume refers to a large-volume compact solid block with the volume of 5 mL-15 mL;

placing a sample cup 427 in the sample cavity 404, placing a large-volume compact solid block with a known volume V _bs in the sample cup 427, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the gas circuit chamber integrated module 400 respectively, and screwing the screw cap 300 clockwise;

In the exhaust stage, the external air source pressure is regulated to enable the absolute air inlet pressure to reach 130kPa, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve are sequentially opened for 121,5 seconds, then the air inlet valve 100 is closed, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as the back pressure P _130bsb and the back temperature T _130bsb,

In the air intake stage, the air intake valve 100 is opened, the temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 seconds as the air intake temperature T _130bsf, the pressure equalizing valve 107 and the air exhaust valve 121 are sequentially closed, the air intake valve 100 is closed after 30 seconds, the pressure data is read after 30 seconds, the air intake valve 100 is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 seconds as the air intake pressure P _130bsf,

In the equalizing stage, the equalizing valve 107 is opened, pressure data is read after 30 seconds, the pressure data is read once every 100ms, the median value of the 20 times of pressure data is continuously read for 2 seconds as equalizing pressure P _130bse, the exhaust valve 121 is opened, temperature data is read, the pressure data is read once every 100ms, the median value of the 20 times of temperature data is continuously read for 2 seconds as equalizing temperature T _130bse,

According to the law of conservation of mass, the number of moles of gas in the free space of the sample cavity 404 in the gas inlet stage is equal to the number of moles of gas in the free space of the sample cavity 404 and the reference cavity 406 in the pressure equalizing stage, namely:

V _fbs is the free space volume of the sample cavity 404 after the large-volume solid block is placed, V _r is the free space volume of the reference cavity 406, R is a universal gas constant, and the ratio of the free space volume V _fbs of the sample cavity 404 when the large-volume solid block is placed to the free space volume V _r of the reference cavity 406 is calculated, namely, the large volume coefficient C _130bs when the air inlet pressure is 130kPa absolute pressure, namely:

Raising the air inlet pressure to 135kPa, continuing to exhaust, air inlet and pressure equalizing to obtain a large volume coefficient when the air inlet pressure is 135kPa, and obtaining a large volume coefficient when the air inlet pressure is 230 kPa; forming a large volume coefficient reference table C _130bs、C_135bs、C_140bs、…、C_230bs at different intake pressures;

s2: small volume coefficient measurement at constant intake pressure: according to the material pressure requirement, determining the air inlet pressure to be a certain constant value;

placing a sample cup 427 in the sample cavity 404, placing a small-volume compact solid block with a known volume V _ss (the small volume refers to the volume being 2 mL-5 mL) in the sample cup 427, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the gas circuit chamber integrated module 400 respectively, and screwing the screw cover 300 clockwise;

In the exhaust stage, the external air source pressure is regulated to be a certain constant value, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve 121,5 seconds are sequentially opened, the air inlet valve 100 is closed, the pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as the back pressure P _xssb and the back temperature T _xssb,

In the air intake stage, the air intake valve 100 is opened, the temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 seconds as the air intake temperature T _xssf, the pressure equalizing valve 107 and the air exhaust valve 121 are sequentially closed, the air intake valve 100 is closed after 30 seconds, the pressure data is read after 30 seconds, the air intake valve 100 is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 seconds as the air intake pressure P _xssf,

In the equalizing stage, the equalizing valve 107 is opened, pressure data is read after 30 seconds, the pressure data is read once every 100ms, the median value of the 20 times of pressure data is continuously read for 2 seconds as equalizing pressure P _xsse, the exhaust valve 121 is opened, temperature data is read, the pressure data is read once every 100ms, the median value of the 20 times of temperature data is continuously read for 2 seconds as equalizing temperature T _xsse,

According to the law of conservation of mass, the number of moles of gas in the free space of the sample cavity 404 in the gas inlet stage is equal to the number of moles of gas in the free space of the sample cavity 404 and the free space of the reference cavity 406 in the pressure equalizing stage when the small-volume compact solid block is placed, namely:

V _fss is the free space volume of the sample cavity 404 after the small-volume solid block is placed, V _r is the free space volume of the reference cavity 406, R is a universal gas constant, and the ratio of the free space volume V _fss of the sample cavity 404 when the small-volume solid block is placed to the free space volume V _r of the reference cavity 406 is calculated, namely, the small volume coefficient C _xss when the air inlet pressure is a certain constant value is:

S3: apparent density measurement of sample at constant inlet pressure: interpolation calculation is carried out on the large volume coefficient C _xbs corresponding to a certain constant value of the air inlet pressure in a large volume coefficient reference table under different air inlet pressures, namely:

The small volume coefficient C _xss when the combined intake pressure is a certain constant value is that:

Calculating a free space volume V _r of reference chamber 406 and a free space volume V _fc of sample chamber 404 when sample cup 427 is placed therein;

Keeping the air inlet pressure the same as the air inlet pressure of the small volume coefficient measuring step under the constant air inlet pressure, opening the spiral cover 300 in the anticlockwise direction, taking out the sample cup 427, weighing a sample with known mass m, placing the sample cup 427 with the sample in the sample cavity 404, aligning the rear pin 306 and the front pin 308 of the upper end cover sealing blind plate 303 with the rear positioning hole 426 and the front positioning hole 425 of the air circuit chamber integrated module 400 respectively, and screwing the spiral cover 300 in the clockwise direction;

In the exhaust stage, the air inlet valve 100, the pressure equalizing valve 107 and the exhaust valve 121,5 seconds are sequentially opened, the air inlet valve 100 is closed, the pressure and temperature data are read after 30 seconds, the pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, the median value of the pressure data and the median value of the temperature data in 20 times are respectively used as the back pressure P _xsb and the back temperature T _xsb,

In the air intake stage, the air intake valve 100 is opened, the temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 20 seconds as the air intake temperature T _xsf, the pressure equalizing valve 107 and the air exhaust valve 121 are sequentially closed, the air intake valve 100 is closed after 30 seconds, the pressure data is read after 30 seconds, the air intake valve 100 is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 20 seconds as the air intake pressure P _xsf,

In the equalizing stage, the equalizing valve 107 is opened, pressure data is read after 30 seconds, the pressure data is read once every 100ms, the medium value of the 20 times of pressure data is continuously read for 2 seconds as equalizing pressure P _xse, the exhaust valve 121 is opened, temperature data is read once every 100ms, the medium value of the 20 times of temperature data is continuously read for 2 seconds as equalizing temperature T _xse, and according to the law of conservation of mass, the mole number of gas in a free space when a sample is placed in the sample cavity 404 in the air intake stage is equal to the mole number of gas in the free space when the sample is placed in the sample cavity 404 and the free space of the reference cavity 406 in the equalizing stage, namely:

The ratio of the free space volume V _fs of the sample chamber 404 when the sample is placed to the free space volume V _r of the reference chamber 406 is calculated as:

the free space volume V _r of the reference chamber 406 is a known quantity, which is calculated as the free space volume V _fs of the sample chamber 404 when the sample is placed, i.e.:

V_fs＝C_xs V_r

The volume V _s of the sample is then calculated from the free space volume V _fc of the sample chamber 404 when the sample cup 427 is placed, i.e.:

V_s＝V_fc-V_fs

The apparent density ρ of the sample is calculated from the sample mass m, namely:

ρ＝m/V_s

the device and the testing method for measuring the apparent density of the powder material based on the exhaust method realize the measurement of the apparent density of the powder material.

The following describes specific embodiments.

Example 1

The present examples determine the apparent density of powder material floating beads.

Adopting a 7.8868mL large-volume compact block, determining that C _150bs under the absolute pressure of 150kPa is 0.91349, determining that C _155bs under the absolute pressure of 155kPa is 0.91329, adopting a 2.3201mL small-volume compact block, determining that C _152ss under the absolute pressure of 152kPa is 2.2996, and obtaining that the volume coefficient C _152bs of the corresponding large-volume compact block is:

Taking 3.1425g of powder material floating beads, placing the powder material floating beads into a sample cup, and measuring the volume coefficient C _152s of the powder material floating beads to be 1.8097, wherein the free space volume V _fs of a sample cavity when a sample is placed is as follows:

V_fs＝C_152s V_r＝1.8097×4.0157＝7.2672mL

the volume of the floating beads is as follows:

V_s＝V_fc-V_fs＝11.5547-7.2672＝4.2875mL

the apparent density ρ of the floating beads is:

ρ＝m/V_s＝3.1425/4.2875＝0.7329g/mL

While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.

Claims

1. The device for measuring the apparent density of the powder material based on the exhaust method is characterized by comprising a gas filtering and guiding system, a gas temperature stabilizing and measuring system, an upper end cover sealing and fastening system, a gas circuit chamber integrated module, a lower end cover sealing and fastening system, an absolute pressure sensor and a sample cup;

The gas filtering and guiding system comprises an air inlet valve, a pressure equalizing valve, an air outlet valve, a top filter screen, a filter element, a bottom filter screen, an upper O-shaped ring and a lower O-shaped ring;

2. The device for measuring apparent density of powder material based on exhaust method according to claim 1, wherein the inlet of the air inlet valve is aligned with the air inlet, the outlet of the air inlet valve is aligned with the inlet of the sample chamber, the fastening screw is screwed into the right threaded hole of the air inlet valve through the right through hole of the air inlet valve, the fastening screw is screwed into the left threaded hole of the air inlet valve through the left through hole of the air inlet valve, and after the fastening screw is screwed, the air inlet valve is sealed with the air channel chamber integration module through the sealing gasket of the inlet valve and the sealing gasket of the outlet of the air inlet valve;

3. The device for measuring apparent density of powder materials based on an exhaust method according to claim 1, wherein the top end filter screen is folded and coated at the upper end of the filter core, the top end filter screen after being tightly folded by the upper end O-shaped ring is placed in the upper end O-shaped ring sealing groove, the bottom end filter screen is folded and coated at the lower end of the filter core, the bottom end filter screen after being tightly folded by the lower end O-shaped ring is placed in the lower end O-shaped ring sealing groove, a filter assembly is formed, the filter assembly is placed in the filter hole, and the upper end O-shaped ring and the lower end O-shaped ring are matched with the filter hole to filter the powder materials.

4. The device for measuring the apparent density of the powder material based on the exhaust method according to claim 1, wherein the inlet of the capillary red copper spiral pipe is connected with an external air source, the outlet of the capillary red copper spiral pipe sequentially penetrates through the back taper joint and the cutting sleeve, the back taper joint is arranged in a hole corresponding to the external air source interface and is connected with the external air source interface through fastening threads, the cutting sleeve is made of soft materials, the radial surface of the cutting sleeve is extruded to form a seal with the periphery of the channel in the screwing process of the back taper joint, and the temperature sensor is arranged in the gas temperature measuring channel.

5. The device for measuring apparent density of powder material based on exhaust method according to claim 1, wherein the front pin is screwed with the front pin hole, the rear pin is screwed with the rear pin hole, the upper end cover O-ring is placed in the upper end cover O-ring sealing groove, the front pin is placed in the front positioning hole, and the rear pin is placed in the rear positioning hole;

6. The device for measuring apparent density of powder materials based on an exhaust method according to claim 1, wherein the rear sealing bolt of the lower end cover passes through the rear sealing through hole of the lower end cover from bottom to top, is screwed into the rear fastening threaded hole of the lower end cover, the left sealing bolt of the lower end cover passes through the left sealing through hole of the lower end cover from bottom to top, is screwed into the left fastening threaded hole of the lower end cover, the right sealing bolt of the lower end cover passes through the right sealing through hole of the lower end cover from bottom to top, is screwed into the right fastening threaded hole of the lower end cover, and the rear sealing bolt of the lower end cover, the left sealing bolt of the lower end cover and the right sealing bolt of the lower end cover tightly press the O-shaped ring of the lower end cover on the bottom end of the gas circuit chamber integrated module through the sealing blind plate of the lower end cover to form sealing for a reference chamber;

7. The device for determining apparent density of powder material based on exhaust method according to claim 1, wherein the absolute pressure sensor is connected with the gas circuit chamber integrated module at the pressure taking hole through threads.

8. The device for measuring apparent density of powder material based on exhaust method according to claim 1, wherein the material of the gas circuit chamber integrated module is organic glass with a thermal conductivity coefficient of 0.14W/(m-K) to 0.2W/(m-K).

9. The device for measuring apparent density of powder material based on exhaust method according to claim 1, wherein the air inlet valve, the pressure equalizing valve and the air outlet valve are all seat-mounted electromagnetic valves, and are sealed with smooth plane through sealing gaskets.

10. The method for using the device for measuring apparent density of powder material based on the exhaust method according to claim 1, comprising the steps of:

S1: measurement of the large volume coefficient under different intake pressures: the measurement of the volume coefficient under different air inlet pressures is to change the air inlet pressure every 5 to kPa between 130 kPa and 230kPa of absolute pressure, and the volume coefficient corresponding to the known large-volume compact solid block is measured; the method comprises the following steps:

In the exhaust stage, the external air source pressure is regulated to enable the absolute air inlet pressure to reach 130 kPa, an air inlet valve, an equalizing valve and an exhaust valve are sequentially opened, the air inlet valve is closed after 5 seconds, pressure and temperature data are read once every 100ms, 20 times of continuous reading are carried out in 2 seconds, and the median value of the 20 times of pressure data and the median value of the temperature data are respectively used as back pressure and back temperature;

according to the law of conservation of mass, the mole number of gas in a free space when the sample cavity is used for placing a large-volume compact solid block in the air inlet stage is equal to the mole number of gas in the free space when the sample cavity is used for placing the large-volume compact solid block in the pressure equalizing stage and the free space of the reference cavity, and the ratio of the free space volume when the sample cavity is used for placing the large-volume compact solid block to the free space volume of the reference cavity is calculated, namely the large volume coefficient when the air inlet pressure is 130 kPa;

Raising the air inlet pressure to 135 kPa, continuing to exhaust, air inlet and pressure equalizing to obtain a large volume coefficient when the air inlet pressure is 135 kPa, and continuing to raise the pressure by 5kPa sequentially until the large volume coefficient when the air inlet pressure is 230kPa is obtained to form a large volume coefficient reference table under different air inlet pressures;

S2: small volume coefficient measurement at constant intake pressure: according to the material pressure requirement, determining that the air inlet pressure is a constant value P1; placing a sample cup in a sample cavity, placing a small-volume compact solid block with a known volume in the sample cup, aligning a rear pin and a front pin of a sealing blind plate of an upper end cover with a rear positioning hole and a front positioning hole of a gas circuit chamber integrated module respectively, and screwing down a screw cap clockwise;