CN113145288B - A new type of microbead screening device and method - Google Patents

Abstract

The invention discloses a novel microbead screening device, which comprises: a water tank with a certain height, wherein liquid with a certain horizontal flow velocity V is contained in the water tank; the container is arranged above the water tank and is used for containing microbeads to be screened; a clamping groove is arranged below the container, a clamping plate capable of being pulled out is arranged in the clamping groove, and when the clamping plate is pulled out, microbeads in the container fall into the water tank to carry out sedimentation screening; the collection channel is arranged at the bottom of the water tank and used for screening and collecting microbeads, and comprises first to nth partition boards which are sequentially arranged according to the flowing direction of the liquid; wherein a first collecting channel is formed between the first baffle and the second baffle, a second collecting channel is formed between the second baffle and the third baffle, a third collecting channel … … is formed between the third baffle and the fourth baffle, and an n-1 collecting channel is formed between the n-1 baffle and the n-1 baffle. The invention can realize screening a large number of microbeads at a time by arranging the container.

Description

A new type of microbead screening device and method

Technical field

The invention is applied in the field of microbead production, and specifically relates to a new type of microbead device and method.

Background technique

Glass beads are a new type of material that has developed rapidly in recent years, has a wide range of uses, and has special properties. It is used in rust removal of aerospace machinery, zebra crossings, no-stop lines, double yellow lines on urban traffic roads, and night reflections on traffic signs. Reflective device at night. At present, in the manufacturing process of reflective microglass beads, in order to select particles of equal diameters, particle sieves are often used for screening. However, the particle sieve screening speed is slow, the efficiency is low, and it cannot be adapted to large-scale production.

Contents of the invention

The purpose of the present invention is to provide a new microbead screening device and method, which improves the efficiency of microbead screening.

In order to solve the above technical problems, the present invention provides a technical solution: a new microbead screening device, including:

A water tank with a certain height, which contains liquid with a certain horizontal flow rate V;

A container is arranged above the water tank for holding microbeads to be screened. The microbeads include microbeads with equivalent diameters of d _p1 , d _p2 , d _p3 ...d _p(n-1) respectively; container There is a card slot below, and a removable card plate is provided in the card slot. When the card plate is pulled away, the microbeads in the container fall into the water tank for sedimentation and screening;

A collection channel is provided at the bottom of the water tank for screening and collecting microbeads, and includes first to nth partitions arranged in sequence according to the flow direction of the liquid; wherein a first partition is formed between the first partition and the second partition. Collection channel, the second collection channel is formed between the second partition and the third partition, and the third collection channel is formed between the third partition and the fourth partition... Between the n-1th partition and the nth partition The n-1th collection channel is formed between them; the first collection channel, the second collection channel, the third collection channel... the n-1th collection channel are used to collect the equivalent diameters of d _p1 , d _p2 , d _p3 ...d respectively. _p(n-1) microbeads;

The height and position of each partition are determined according to the following formula:

The vertical distance between the upper end of the first partition and the clamping plate is S _n ;

The vertical distance between the upper end of the second partition and the clamping plate is S _n ;

The vertical distance between the upper end of the third partition and the clamping plate is S _n -h ₂ ;

The vertical distance between the upper end of the fourth partition and the clamping plate is S _n -h ₃ ;

…

The vertical distance between the upper end of the n-th partition and the clamping plate is _Sn -h _n-1 ;

in

The horizontal distances between the n-th partition, the n-1 partition, the n-2 partition...the second partition and the right side of the container are W _n-1 , W _n-2 , W _n-3 ...W respectively. ₁ ;

in In the formula, ρ _p is the density of the microbeads, ρ is the density of the liquid, g is the acceleration of gravity, and μ is the dynamic viscosity.

According to the above solution, a stirring water tank is connected to the side of the water tank for generating liquid with a certain horizontal flow rate V.

According to the above scheme, the n=4.

A microbead screening method includes the following steps:

S1. Put the microbeads to be screened into the container. When the horizontal flow rate of the liquid in the water tank is constant speed V, pull out the card and the microbeads fall into the water tank;

S2. Microbeads with different equivalent diameters settle under the influence of the liquid with a horizontal flow rate of V in the water tank. The microbeads fall into the first to n-1 collection channels from large to small according to the different equivalent diameters, so that Complete the screening of microbeads.

According to the above scheme, in S1, the size of each part in the water tank is designed according to the diameter and density of the beads to be screened, the density of the liquid in the container, and the preset horizontal flow rate V.

According to the above scheme, in S1, liquid is first added to the water tank, and the stirring water tank connected to the side of the water tank is started. When the horizontal flow rate of the liquid reaches a uniform speed V, the microbeads to be screened are then placed into the water tank.

The beneficial effects of the present invention are: by setting up a container, a large number of microbeads can be screened at a time; by setting up a water tank and a collection channel, and utilizing the differences in the horizontal movement speed and settling speed of microbeads with different equivalent diameters in the flowing liquid, it can be achieved Rapid screening of microbeads;

Furthermore, this device can adjust the position and width of the collection channel by adjusting the distance between each partition and the right side of the container, thereby adjusting the specifications of the microbeads collected by the collection channel;

Furthermore, by setting the height of different partitions, this device can realize that microbeads with different equivalent diameters fall into the collection channel at the same time, further improving the screening efficiency of microbeads.

Description of drawings

Figure 1 is a schematic structural diagram of an embodiment of the present invention;

In the picture: 1-sink, 2-container, 3-cardboard, 4-microbeads, 5-first collection channel, 6-second collection channel, 7-third collection channel, 8-first partition, 9 -Second partition, 10-Third partition, 11-Fourth partition.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present disclosure.

Referring to Figure 1, a new type of microbead screening device includes:

The water tank 1 has a certain height, and the water tank 1 contains liquid with a certain horizontal flow rate V;

Container 2 is set above the water tank 1 and is used to hold microbeads 4 to be screened. The microbeads 4 include microbeads 4 with equivalent diameters of d _p1 , d _p2 , d _p3 ... d _{p (n-1)} ; There is a card slot below the container 2, and a removable card plate 3 is provided in the card slot. When the card plate 3 is pulled away, the microbeads 4 in the container 2 fall into the water tank 1 for sedimentation and screening;

The collection channel is provided at the bottom of the water tank 1 for screening and collecting microbeads 4, and includes first to nth partitions arranged in sequence according to the flow direction of the liquid; where the first partition 8 and the second partition 9 The first collection channel 5 is formed between, the second collection channel 6 is formed between the second partition 9 and the third partition 10, the third collection channel 7 is formed between the third partition 10 and the fourth partition 11... The n-1th collection channel is formed between the n-1 partition and the n-th partition; the first collection channel 5, the second collection channel 6, the third collection channel 7... the n-1th collection channel are used for collection respectively. Microbeads 4 with equivalent diameters d _p1 , d _p2 , d _p3 ...d _p(n-1) ;

The height and position of each partition are determined according to the following formula:

The vertical distance between the upper end of the first partition plate 8 and the clamping plate 3 is _Sn ;

The vertical distance between the upper end of the second partition plate 9 and the clamping plate 3 is _Sn ;

The vertical distance between the upper end of the third partition 10 and the clamping plate 3 is _Sn -h ₂ ;

The vertical distance between the upper end of the fourth partition plate 11 and the clamping plate 3 is _Sn -h ₃ ;

…

The vertical distance between the upper end of the n-th partition and the clamping plate 3 is _Sn -h _n-1 ;

in By setting different partition heights, all acquisition channels have the fastest acquisition speed;

The horizontal distances between the n-th partition, the n-1 partition, the n-2 partition...the second partition 9 and the right side of the container 2 are W _n-1 , W _n-2 , W _n-3 ... respectively. …W ₁ ;

in In the formula, ρ _p is the density of microbeads 4, ρ is the density of the liquid, g is the acceleration of gravity, and μ is the dynamic viscosity.

Furthermore, a stirring water tank is connected to the side of the water tank 1 for generating liquid with a certain horizontal flow rate V.

Further, the n=4.

In this embodiment, microbeads 4 include three specifications of equivalent diameters, namely d _p1 =1000 μm, d _p2 =100 μm, and d _p3 =10 μm; the movement process of microbeads 4 is analyzed in detail below:

During the settling process of microbeads 4, their vertical motion is divided into accelerated motion process and uniform motion process;

a) Analysis of uniform motion process of microbeads

When the microbead 4 moves at a constant speed, the microbead 4 is subjected to gravity (mg), buoyancy and drag force Assume that the movement speed of microbead 4 at this time is u _t , then there is:

Organize and get the speed formula:

Where d _p is the diameter of the microbead 4, ξ _D is the drag coefficient, ρ _p is the density of the microbead 4, and ρ is the density of the liquid;

According to fluid mechanics, it can be known:

1. Re _p ≤ 2, it is the laminar flow zone, also known as the Stokes zone. At this time

2. 2≤Re _p ≤500, which is the transition zone, also known as the Allen zone. At this time

3. 500<Re _p <2×10 ⁵ is the turbulent zone, also known as the Newton zone. At this time

_ξD≈0.44 (5)

4. When Re _p ≥2×10 ⁵ , ξ _D will suddenly drop and show irregularities;

Among them, Re _p is the Reynolds number, Re _p =d _p u _t ρ/μ, the drag coefficient ξ _D is a function of the Reynolds number, and μ is the dynamic viscosity (Pa·S). In this embodiment, only the laminar flow region is tested. analyze.

Substituting the drag coefficient ξ _D in equation (3) into the expression of settlement velocity u _t , we get:

During the settling process, different microbeads 4 will interfere with each other. The microbeads 4 have irregular shapes such as filamentous and flaky shapes. When calculating, the equivalent diameter should be substituted and corrected by the following formula:

Among them, i is the volume ratio of microbeads 4 to liquid; α is the shape influence factor, which is a function of i. The relationship formula is as follows:

Table 1 Factors affecting the shape of sedimentation velocity microbeads

Microbead situation i range α value formula Irregular microbeads 0.15～0.5 α＝1+305i ^2.84 Spherical beads 0.2～0.5 α＝1+229i ^3.43 Very thin suspension i<0.15 α=1～2

b) Analysis of accelerated movement of microbeads

When the microbead 4 accelerates in the liquid, the forces it receives in the vertical direction include buoyancy force F _b , drag force F _D , and gravity F _B , so there is:

Where ρ _p is the density of microbeads 4, and ρ is the density of liquid;

According to Newton's second law:

F _B ＝F _b -F _D ＝ma (11)

In the formula, ξ _D is the drag coefficient, A is the projected area of the microbead 4 in the flow direction, and a is the acceleration of the microbead 4.

The motion equation of microbead 4 is established as follows:

S＝A+Bt+Ct ² +Dt ³ (12)

S′＝B+2Ct+3Dt ² (13)

S″＝2C+6Dt (14)

S″′＝6D (15)

In the formula, S is the height of the settlement of microbead 4, and A, B, C, and D are the undetermined coefficients of the cubic equation of equation (12); when t=0, we can get:

S＝A+Bt+Ct ² +Dt ³ =0 (16)

It can be obtained that A=0;

When microbead 4 starts to move, its speed is 0, that is, S′=0, so there is:

S′＝B+2Ct+3Dt ² =0 (17)

It can be obtained that B=0;

Substituting A=0 and B=0 into formula (12), formula (13), formula (14), and formula (15), we get:

S＝Ct ² +Dt ³ (18)

S′＝2Ct+3Dt ² (19)

Since when microbead 4 first starts moving, its speed is 0 and the drag force it experiences is also 0. The force on microbead 4 at this time can be expressed as:

Among them, a ₀ is the initial acceleration, m is the mass of microbead 4, so we can get:

From formula (8), formula (9), and formula (11), we can get:

S″＝2C+6Dt＝a ₀ (22)

Substituting t=0 into equation (23) we get:

Assume that when t=T, the gravity, buoyancy and drag force on the microbead 4 are balanced. According to equation (6):

Because the resultant force in the vertical direction of microbead 4 is 0 at this time, that is, the acceleration is also 0, S″=0, so there is:

S″＝2C+6DT＝0 (26)

Substitute equation (27) into equation (25):

The solution of substituting equation (24) into (28) is:

Substituting formula (29) and formula (24) into formula (28), we can get:

Among them, T represents the time required for the microbead 4 to reach equilibrium from the beginning of its movement to the gravity, buoyancy, and drag force. Although Equation (30) cannot directly conclude that T is directly related to the specific gravity of the microbead 4 and the liquid, the dynamic force The viscosity μ is directly related to the specific gravity of the liquid, μ=ρν, where ν is the kinematic viscosity;

Substitute equation (30), equation (29), and equation (24) into equation (18) to obtain the height distance of movement required for the three forces on microbead 4 to reach equilibrium:

In this example, the device is in an environment of 20°C, the dynamic viscosity of the microbeads 4 and the liquid is 1 Pa·S, and the equivalent diameters of the microbeads 4 are divided into 10 μm, 100 μm, and 1000 μm. The sedimentation processes of the three types of microbeads 4 are analyzed below. ;

Through equation (30), it can be obtained that the movement time and movement distance required for the three forces received by the three types of microbeads 4 to reach equilibrium during the accelerated movement are:

The equivalent diameter of microbeads is 10μm:

The equivalent diameter of microbeads is 100μm:

The equivalent diameter of microbeads is 1000μm:

It can be seen from this that the time and distance of the accelerated motion process of microbeads 4 of three different equivalent diameters are very small and can be ignored. The process of uniform motion of microbeads 4 in the liquid is analyzed below:

(a) When the diameter of microbead 4 is 10 μm:

Microbead 4 moves at a uniform speed after the three forces it receives reach equilibrium. Its initial speed is:

The settling time is:

(b) When the diameter of microbead 4 is 100 μm:

In the same way, we can get:

(c) When the diameter of microbead 4 is 1000 μm:

In the same way, we can get:

Among them, H ₁ , H ₂ , and H ₃ respectively correspond to the distance in the vertical direction component of the movement length of microbeads 4 with diameters of 10 μm, 100 μm, and 1000 μm from the time when they start to move at a constant speed until they enter the collection channel. Since the microbeads 4 move in the vertical direction The motion is divided into accelerated motion process and uniform motion process, so there are:

S _n =S ₁ +H ₁ =S ₂ +H ₂ =S ₃ +H ₃ (44)

Where S _n is the vertical displacement distance of microbead 4 from leaving container 3 to entering the collection channel. Since S ₁ , S ₂ , and S ₃ are all very small and can be ignored, so:

H ₁ =H ₂ =H ₃ =S _n (45)

It can be seen that when the diameter of the microbead 4 is 1000 μm, the time t ₃ required for its settlement is the shortest, corresponding to the first collection channel 5, and the microbeads 4 with diameters of 100 μm and 10 μm correspond to the second collection channel 6 and the third collection respectively. Channel 7.

When the diameter of microbeads is 1000 μm and falls into the first collection channel 5, the collection time, that is, the settling time _t3 is the shortest. If the collection speed of the second collection channel 6 is as fast as the first collection channel 5, the third collection channel 6 needs to be made as fast as the first collection channel 5. The partition 10 is higher than the second partition 9 by h ₂ , then:

Calculate:

In the same way, if you want to make the collection speed of the third collection channel 7 as fast as that of the first collection channel 5, you need to make the fourth partition 11 higher than the second partition 9 by h ₃ , then:

Calculate:

The horizontal distance between the right side of the container 2 and the fourth partition 11 is W ₃ ; W ₃ is the horizontal displacement distance of the microbeads 4 falling into the third collection channel 7 during the settling process; the value of W ₃ is:

The horizontal distance between the right side of the container 2 and the third partition 10 is W ₂ ; W ₂ is the horizontal displacement distance of the microbeads 4 falling into the second collection channel 6 during the settling process; the value of W ₂ is:

The horizontal distance between the right side of the container 2 and the second partition 9 is W ₁ ; W ₁ is the horizontal displacement distance of the microbeads 4 falling into the first collection channel 5 during the settling process; the value of W ₁ is:

A new microbead screening method includes the following steps:

S1. Put the microbeads 4 to be screened into the container 2. When the horizontal flow rate of the liquid in the water tank 1 is a constant speed V, pull out the card 3 and the microbeads 4 fall into the water tank 1;

S2. Microbeads 4 with different equivalent diameters settle under the influence of liquid with a horizontal flow rate V in the water tank 1. Microbeads 4 fall into the first to n-1 collections from large to small according to different equivalent diameters. channel, thereby completing the screening of microbeads 4.

Further, in S1, the size of each part in the water tank 1 is designed according to the diameter and density of the microbeads 4 to be screened, the density of the liquid in the container 2, and the preset horizontal flow rate V.

Further, in the described S1, liquid is first added to the water tank 1, and the stirring water tank connected to the side of the water tank 1 is started. When the horizontal flow rate of the liquid reaches a uniform speed V, the microbeads 4 to be screened are then placed into the water tank 1. .

In summary, the present invention generates a liquid with a certain horizontal flow rate in the water tank by setting up a stirring water tank. During the settling process, the microbeads are affected by the liquid flow rate and fall into the collection channel at the preset position. According to the different equivalent diameters of microbeads, The sedimentation velocity increases the partition wall of the corresponding collection channel, so that the collection speed of all collection channels reaches the maximum.

The above are only examples of the present invention, and do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description and drawings of the present invention, or directly or indirectly applied to other related technologies fields are equally included in the scope of patent protection of the present invention.

Claims (6)

1. A new type of microbead screening device, characterized in that: this device includes: A water tank with a certain height, which contains liquid with a certain horizontal flow rate V; A container is arranged above the water tank for holding microbeads to be screened. The microbeads include microbeads with equivalent diameters of d _p1 , d _p2 , d _p3 ...d _p(n-1) respectively; container There is a card slot below, and a removable card plate is provided in the card slot. When the card plate is pulled away, the microbeads in the container fall into the water tank for sedimentation and screening; A collection channel is provided at the bottom of the water tank for screening and collecting microbeads, and includes first to nth partitions arranged in sequence according to the flow direction of the liquid; wherein a first partition is formed between the first partition and the second partition. Collection channel, the second collection channel is formed between the second partition and the third partition, and the third collection channel is formed between the third partition and the fourth partition... Between the n-1th partition and the nth partition The n-1th collection channel is formed between them; the first collection channel, the second collection channel, the third collection channel... the n-1th collection channel are used to collect the equivalent diameters of d _p1 , d _p2 , d _p3 ...d respectively. _p(n-1) microbeads; The height and position of each partition are determined according to the following formula: The vertical distance between the upper end of the first partition and the clamping plate is S _n ; The vertical distance between the upper end of the second partition and the clamping plate is S _n ; The vertical distance between the upper end of the third partition and the clamping plate is S _n -h ₂ ; The vertical distance between the upper end of the fourth partition and the clamping plate is S _n -h ₃ ; … The vertical distance between the upper end of the n-th partition and the clamping plate is _Sn -h _n-1 ; in The horizontal distances between the n-th partition, the n-1 partition, the n-2 partition...the second partition and the right side of the container are W _n-1 , W _n-2 , W _n-3 ...W respectively. ₁ ; in In the formula, ρ _p is the density of the microbeads, ρ is the density of the liquid, g is the acceleration of gravity, and μ is the dynamic viscosity. 2. The new microbead screening device according to claim 1, characterized in that: a stirring water tank is connected to the side of the water tank for generating liquid with a certain horizontal flow rate V. 3. The novel microbead screening device according to claim 1, characterized in that: n=4. 4. The microbead screening method realized by the novel microbead screening device according to any one of claims 1 to 3, characterized in that: this method includes the following steps: S1. Put the microbeads to be screened into the container. When the horizontal flow rate of the liquid in the water tank is constant speed V, pull out the card and the microbeads fall into the water tank; S2. Microbeads with different equivalent diameters settle under the influence of the liquid with a horizontal flow rate of V in the water tank. The microbeads fall into the first to n-1 collection channels from large to small according to the different equivalent diameters, so that Complete the screening of microbeads. 5. The microbead screening method according to claim 4, characterized in that: in the S1, the water tank is designed according to the diameter and density of the microbeads to be screened, the density of the liquid in the container, and the preset horizontal flow rate V. the dimensions of each part. 6. The microbead screening method according to claim 4, characterized in that: in the described S1, liquid is first added to the water tank, and the stirring water tank connected to the side of the water tank is started. When the horizontal flow rate of the liquid reaches a uniform speed V, Then put the microbeads to be screened into the water tank.