阅读说明：本技术 一种去除球形粉末中不规则颗粒的装置及其去除方法 (Device and method for removing irregular particles in spherical powder ) 是由 石明 黄见洪 林文雄 刘燕辉 林紫雄 于 2021-06-03 设计创作，主要内容包括：本发明公开了一种去除球形粉末中不规则颗粒的装置及其去除方法,属于高性能粉末制造技术领域。本发明的装置包括料斗、倾斜平板、水平台面和收料装置,实现去除球形粉末中不规则粉末,提高了球形粉末的球形率、流动性。本发明的去除方法,去除球形颗粒上的一些黏附灰份以及一些流动性差的小颗粒球形颗粒,提高了用于3D打印球形粉末的质量,增加了3D打印使用的性能效果。本发明的去除球形粉末中不规则颗粒的装置和去除方法,操作简单,不仅可实现小批量的球形粉末去除操作,也可以制成大尺寸装置,并实现自动化,从而在制粉生产线上使用。本发明还公开了的球形粉末中不规则颗粒含量的测量方法。(The invention discloses a device and a method for removing irregular particles in spherical powder, and belongs to the technical field of high-performance powder manufacturing. The device comprises the hopper, the inclined flat plate, the horizontal table surface and the material receiving device, irregular powder in the spherical powder is removed, and the sphericity rate and the flowability of the spherical powder are improved. The removing method provided by the invention can be used for removing some adhering ash and small-particle spherical particles with poor fluidity from the spherical particles, so that the quality of the spherical powder for 3D printing is improved, and the performance effect of 3D printing is improved. The device and the method for removing irregular particles in spherical powder are simple to operate, can not only realize small-batch spherical powder removal operation, but also can be manufactured into a large-size device, and realize automation, so that the device and the method are used on a powder manufacturing production line. The invention also discloses a method for measuring the content of irregular particles in the spherical powder.)

1. The device for removing irregular particles in spherical powder is characterized by comprising a hopper, an inclined flat plate, a horizontal table top and a material receiving device; the hopper is positioned above the inclined flat plate, and the material receiving device is positioned below the horizontal table top; the inclination of the inclined flat plate is theta (namely an included angle theta is formed between the inclined flat plate and the horizontal direction), and the horizontal table top is parallel to the horizontal direction; the lower end of the inclined flat plate is connected to one end of the horizontal table top, and the material receiving device is arranged at the other end of the horizontal table top.

2. The apparatus according to claim 1, wherein the ratio of the length of the inclined plate to the length of the horizontal table top is in the range of 8-20, preferably 10-15;

preferably, the length of the horizontal table top is 5-50 mm;

preferably, the inclination theta of the inclined flat plate is 10-70 DEG

Preferably, the hopper and the inclined flat plate are adjustably fixed on a support frame; preferably, the support frame is further provided with a support rod, and the height or the inclination of the hopper and the inclined flat plate can be adjusted through the support rod;

preferably, the inclined flat plate and the horizontal table top are detachably arranged on the device;

preferably, the surface roughness Ra of the inclined flat plate and the horizontal table-board is less than 0.2 μm; preferably, the inclined flat plate and the horizontal table top are selected from a stainless steel plate and a glass plate.

3. The apparatus of claim 1 or 2, wherein the receiving means comprises a spherical particle receiving tank and an irregular particle receiving tank;

preferably, the lower end of the hopper is provided with a feed opening;

preferably, the feed opening of the hopper is a long narrow opening; preferably, the width of the narrow opening is 1-5 mm;

preferably, a gap is formed between the lower end of the feed opening and the upper surface of the inclined flat plate; preferably, the gap is 1-3 mm.

4. The device according to any one of claims 1 to 3, wherein the spherical powder has an average particle diameter of 15 to 500 μm; preferably, the flowability of the spherical powder is 20-40s/50 g;

preferably, the spherical powder is selected from at least one of metal powder, non-metal powder or polymer powder; preferably, the spherical powder comprises irregular particles and spherical particles; preferably, the mass ratio of the spherical particles to the spherical powder is 80 to 95 wt%; preferably, the irregular particles include at least one of plate-like particles, spheroidal particles, hemispherical particles, and the like.

5. A method for removing irregular particles from spherical powder, which is characterized in that the irregular particles in the spherical powder are removed by the device according to any one of claims 1 to 4.

6. The removal method according to claim 5, characterized in that the specific steps of the removal method are as follows:

(1) putting the spherical powder into a hopper;

(2) the spherical powder falls onto the inclined flat plate below from the hopper, the spherical powder slides along the inclined flat plate, spherical particles in the spherical powder roll to the material receiving device, and irregular particles roll to the horizontal table top, so that the spherical particles are separated from the irregular particles;

preferably, the spherical powder added in the hopper may be 1/5-1/3 or 1/10-1/5;

preferably, when the spherical powder is added, the adding speed of the spherical powder is 1-100 g/min;

preferably, the spherical powder may be further subjected to a dehydration treatment before removing the irregular particles.

7. The removing method according to claim 5 or 6, wherein the spherical powder has a particle diameter of 15 to 500 μm; preferably, the flowability of the spherical powder is 20-40s/50 g;

preferably, the flowability of the spherical particles obtained by the above method is improved by 8 to 15% as compared with that of spherical powder.

8. A method for measuring the content of irregular particles in a spherical powder, characterized in that the method for measuring comprises the removal method according to any one of claims 5 to 7.

9. The measurement method according to claim 8, characterized in that the measurement method comprises in particular the steps of:

(A1) weighing spherical powder with the mass M;

(A2) subjecting the spherical powder to the removal method according to any one of claims 5 to 7 to obtain spherical particles;

(A3) collecting spherical particles in the spherical powder, and weighing and recording as m;

(A4) calculating the percentage content of irregular particles in the spherical powder: (M-M)/MX 100%;

preferably, M is preferably 100-1000 g.

10. Use of spherical powder obtained by the device according to any one of claims 1 to 4 or the removal method according to any one of claims 5 to 7 in 3D printing; preferably, the 3D printing comprises SLM 3D printing;

preferably, the spherical powder is 3D printed to obtain an entity; preferably, the density of the body is 99.8%.

Technical Field

The invention belongs to the technical field of high-performance powder manufacturing, and particularly relates to a device and a method for removing irregular particles in spherical powder.

Background

3D printing is an advanced manufacturing technology, can realize the close combination of a novel network technology, an advanced material technology and a digital manufacturing technology, and becomes a core key technology of the third industrial revolution. In the metal 3D printing process, metal spherical powder is a key raw material, and sufficient fluidity and bulk density need to be ensured, so that stable smoothness and high bulk density of powder delivery are ensured. Therefore, various spheroidization techniques are required to obtain spherical powders.

Currently, GAs Atomization (GA), centrifugal atomization (PREP), and Plasma Spheronization (PS) mainly used for refractory metals are the main methods for producing 3D printed metal spherical powder materials. In the powder prepared by the methods, due to the limitation of the process or improper control of the process, powder particles which are not spheroidized or have poor spheroidizing effect are easily generated, for example, GA powder particles may have spheroids, shriveled spheres and satellite spheres, PREP powder particles may also have shriveled spheres and dumbbell-associated particles, PS powder may have particles which are not spheroidized or spherical particles with more neoplasms. These powder particles, which are not spheroidized or have poor spheroidizing effects, will affect the flowability effect of the overall powder and thus the performance effect of the 3D printing application.

In view of the above situation, it is one of the approaches to improve and optimize the process parameters and improve the sphericity ratio in the production process. But due to the limitation of the technology, the sphericity ratio reaches the upper limit and is difficult to improve; or increase the sphericity ratio by decreasing the production efficiency, which results in a decrease in the loss of productivity.

Disclosure of Invention

In order to solve the technical problems, the invention provides a device and a method for removing irregular particles in spherical powder, which are used for removing some irregular particles which are not spheroidized or have poor spheroidization effect and are mixed in the spherical powder, so that the spheroidization rate of the spherical powder is improved, the powder flowability and the stacking density are improved, and the powder performance is further improved.

The invention provides a device for removing irregular particles in spherical powder, which comprises a hopper, an inclined flat plate, a horizontal table top and a material receiving device, wherein the hopper is positioned above the inclined flat plate, and the material receiving device is positioned below the horizontal table top; the inclination of the inclined flat plate is theta (namely an included angle theta is formed between the inclined flat plate and the horizontal direction), and the horizontal table top is parallel to the horizontal direction; the lower end of the inclined flat plate is connected to one end of the horizontal table top, and the material receiving device is arranged at the other end of the horizontal table top.

According to an embodiment of the invention, the ratio of the length of said inclined plate to the length of said horizontal table top is in the range of 8-20, preferably 10-15.

According to an embodiment of the invention, the length of the horizontal table-top is 5-50 mm.

According to an embodiment of the invention, the slope θ of the inclined plate is 10 ° -70 °, preferably 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °.

According to an embodiment of the invention, the hopper and the inclined plate are adjustably fixed to a support frame. Preferably, the support frame is further provided with a support rod, and the hopper and the inclined flat plate can be adjusted in height or inclination through the support rod, so that the distance between the lower end part of the hopper and the inclined flat plate is as small as possible.

According to an embodiment of the invention, said inclined plate and said horizontal table are removably arranged on said device and are replaceable as required.

According to an embodiment of the invention, the surface roughness Ra of the inclined plate and the horizontal mesa is less than 0.2 μm. Preferably, the inclined flat plate and the horizontal table top are made of materials with surface roughness Ra less than 0.2 μm, such as a stainless steel plate, a glass plate and the like, when the spherical powder slides on the inclined flat plate, the resistance generated between the spherical powder and the inclined flat plate is small, and when the spherical powder moves downwards along the inclined flat plate under the action of gravity, enough kinetic energy can be obtained to roll and advance to the material receiving device arranged at the other end of the horizontal table top or the end of the horizontal table top close to the material receiving device; the irregular particles can not obtain enough kinetic energy on the inclined flat plate, when the irregular particles fall on the horizontal table top, the kinetic energy of the irregular particles is rapidly reduced to zero, and the irregular particles stay at one end of the horizontal table top, which is close to the inclined flat plate, or even stay on the inclined flat plate.

According to the embodiment of the invention, the material receiving device comprises a spherical particle receiving tank and an irregular particle receiving tank.

According to an embodiment of the invention, the lower end of the hopper is provided with a feed opening.

Preferably, the feed opening of the hopper is an elongated narrow opening. Preferably, the width of the narrow opening is 1-5 mm.

According to an embodiment of the invention, the narrow discharge opening of the hopper may or may not be in contact with the inclined plate, in order to avoid that the spherical powder is ejected out of the device when falling from the narrow discharge opening of the hopper to the inclined plate.

In one embodiment of the present invention, a gap is provided between the lower end of the feed opening and the upper surface of the inclined flat plate. Preferably, the gap is 1-3mm, preferably 2.5 mm.

According to an embodiment of the invention, the spherical powder has an average particle size of 15 to 500 μm.

According to an embodiment of the invention, the flowability of the spherical powder is 20-40s/50 g.

According to an embodiment of the present invention, the spherical powder is selected from at least one of metal powder, non-metal powder, or polymer powder.

According to an embodiment of the present invention, the spherical powder includes irregular particles and spherical particles.

Preferably, the mass ratio of spherical particles to spherical powder is 80-95 wt%, e.g., 80 wt%, 82 wt%, 85 wt%, 88 wt%, 90 wt%, 93 wt%, 95 wt%, or a range between any two values.

Preferably, the irregular particles include at least one of plate-like particles, spheroidal particles, hemispherical particles, and the like.

The invention also provides a method for removing irregular particles in spherical powder, which removes the irregular particles in the spherical powder by the device for removing the irregular particles in the spherical powder.

According to the embodiment of the invention, the removing method comprises the following specific steps:

(1) putting the spherical powder into a hopper;

(2) spherical powder falls to the slope flat board of below from the hopper, and spherical powder slides along the slope flat board, and spherical particle in the spherical powder rolls to material collecting device, and irregular particle rolls to horizontal mesa, realizes spherical particle and irregular particle separation.

According to an embodiment of the invention, the spherical powder, the spherical particles and the irregular particles have the definitions as described above.

According to an embodiment of the present invention, in the above-mentioned removing method, the amount of the spherical powder added in the hopper at a time is not particularly limited, and the amount added in the hopper at a time of each treatment cannot be so large as to be added as the case may be, in order to prevent the spherical powder from being piled up on the inclined flat plate to affect the operation of removing irregular particles in the spherical powder. Illustratively, the spherical powder added in the hopper may be 1/5-1/3 or 1/10-1/5 of the hopper volume.

According to the embodiment of the present invention, when adding spherical powder, the adding speed can be adjusted according to actual operation, thereby preventing the powder from impacting the inclined flat plate and being ejected out of the device. For example, the rate of addition of the spherical powder is 1 to 100 g/min.

According to an embodiment of the present invention, the spherical powder may be further subjected to a dehydration treatment, such as a heat treatment or a vacuum heat treatment, before removing the irregular particles, thereby improving the flowability of the powder to be treated.

According to an embodiment of the present invention, the inclined plate and the horizontal table are cleaned before adding the spherical powder in step (1). The cleaning is not particularly limited in the present invention, and may be performed by a technique commonly used in the art, for example, solvent wiping, brush sweeping, for example, absolute ethyl alcohol wiping.

According to an embodiment of the invention, the spherical powder has a particle size of 15 to 500 μm.

According to an embodiment of the invention, the spherical powder is a powder having a certain flowability. Illustratively, the flowability of the spherical powder is 20-40s/50g, for example 20s/50g, 25s/50g, 30s/50g, 35s/50g, 40s/50 g.

According to an embodiment of the present invention, the spherical powder is selected from any one of metal powder, non-metal powder, or polymer powder.

Preferably, the metal powder is selected from any one of NiTi, TC4, TA31, Ti, 316L, 304, W, WC, Mo, MoRe, Au, Ag, Cu.

Preferably, the non-metal powder is selected from any one of zirconia spherical powder, alumina, aluminum nitride, silicon oxide, silicon, cerium oxide, and yttrium oxide.

Preferably, the polymer powder is selected from any one of polyethylene, polyvinyl chloride, polypropylene, phenol resin, urea resin, polybutadiene (butadiene rubber), polyisoprene (isoprene rubber), chloroprene rubber, and butyl rubber.

According to an embodiment of the present invention, the flowability of the spherical particles obtained by the above method is improved by 8 to 15% as compared with that of the spherical powder.

The invention also provides a method for measuring the content of irregular particles in the spherical powder, which comprises the removing method.

According to the embodiment of the invention, the method for measuring the content of irregular particles in the spherical powder specifically comprises the following steps:

(A1) weighing spherical powder with the mass M;

(A2) the spherical powder is removed by the method;

(A3) collecting spherical particles in the spherical powder, and weighing and recording as m;

(A4) calculating the percentage content of irregular particles in the spherical powder: (M-M)/M.times.100%.

According to an embodiment of the invention, the removal method has the definition as described above.

According to an embodiment of the present invention, M is preferably 100-1000 g.

According to an embodiment of the present invention, in the step (a1), the spherical powder having a mass M is divided into n parts, preferably, n is 10 to 1000 equal parts.

According to an embodiment of the present invention, in order to ensure the accuracy of the measurement method, in step (a2), the spherical powder added in the hopper is less than 1/3 of the hopper volume, illustratively 1/5-1/3 or 1/10-1/5 of the hopper volume.

According to the embodiment of the present invention, when adding spherical powder, the adding speed can be adjusted according to actual operation, thereby preventing the powder from impacting the inclined flat plate and being ejected out of the device. For example, the rate of addition of the spherical powder is 1 to 100 g/min.

According to an embodiment of the invention, the spherical powder has a particle size of 15 to 500 μm.

According to an embodiment of the invention, the flowability of the spherical powder is between 20 and 40s/50g, such as 20s/50g, 25s/50g, 30s/50g, 35s/50g, 40s/50 g.

Preferably, the spherical powder has the definition as described above.

The invention also provides application of the spherical powder obtained by the device or the method for removing irregular particles in the spherical powder in 3D printing. Preferably, the 3D printing comprises SLM 3D printing.

Preferably, the spherical powder is 3D printed to obtain a solid body. Preferably, the density of the body is 99.8%.

The invention has the beneficial effects that:

1. the invention provides a device for removing irregular particles in spherical powder by utilizing the difference of the flowability of spherical particles and non-spherical particles in the spherical powder, so that the irregular powder in the spherical powder is removed, and the sphericity rate and the flowability of the spherical powder are improved.

2. By the removal method, some adhering ash (such as some nano flocculent substances formed in the PS method preparation) on the spherical particles and some small-particle spherical particles with poor fluidity can be removed, the material loss in the removal process is low, and the waste of spherical powder is avoided; meanwhile, the removing method provided by the invention also improves the quality of the spherical powder for 3D printing, thereby increasing the performance effect of 3D printing.

3. The device and the method for removing irregular particles in spherical powder are simple to operate, can not only realize small-batch spherical powder removal operation, but also can be manufactured into a large-size device, and realize automation, so that the device and the method are used on a powder manufacturing production line.

4. The method for measuring the content of the irregular particles in the spherical powder has small error and strong operability, and is suitable for measuring the content of the irregular particles in various spherical powders.

Drawings

FIG. 1 is a diagram of an apparatus for removing irregular particles from spherical powder according to the present invention; the device comprises a support frame 1, a hopper 2, a support rod 3, an inclined flat plate 4, a support rod 5, a horizontal table 6 and a material receiving tank 7.

FIG. 2 is a scanning electron micrograph of the NiTi spherical powder (prepared by the PS method) not removed in example 1.

FIG. 3 is a scanning electron microscope image of the NiTi spherical powder after removing irregular particles in example 1.

FIG. 4 is a scanning electron micrograph of the irregular particles removed in example 1.

FIG. 5 is a scanning electron microscope image of the NiTi spherical powder after removing irregular particles in comparative example 1.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

A device for removing irregular particles in spherical powder is shown in figure 1, wherein the top is a hopper 2, the feed opening of the hopper 2 is a long narrow opening, the narrow opening can be 1-5mm, an inclined flat plate 4 is fixedly arranged below the hopper 2, and the distance between the feed opening of the hopper 2 and the inclined flat plate 4 is as small as possible; the length of the inclined flat plate 4 is 30-260mm, and the inclination of the inclined flat plate 4 is 10-70 degrees. The lower end of the inclined flat plate 4 is connected with a section of horizontal table top 6, the length of the horizontal table top 6 is 5-50mm, and a material receiving tank 7 is arranged below the horizontal table top 6. The height or the inclination of the fixed position of the hopper 2 and the inclined flat plate 4 is adjusted by the support frame 1, the support rod 3 and the support rod 5 respectively. The inclined plate 4 and the horizontal table top 6 are detachably arranged on the device, and the length of the inclined plate and the horizontal table top is changed as required.

Wherein, the surfaces of the inclined flat plate 4 and the horizontal table top 6 need to be smooth and can be made of stainless steel plates, glass plates and other materials.

In one embodiment of the present invention, the material of the inclined plate 4 and the horizontal table top 6 is selected from stainless steel plate, glass plate, etc. having a surface roughness Ra of less than 0.2 μm.

In the invention, the specific steps of separating and removing irregular powder particles by adopting the device are as follows:

(1) a spoon and other tools are used for containing the powder mixed with the irregular particles into the hopper 2, and the powder can be spread in the hopper 2 due to certain fluidity of the powder;

(2) when the powder is spread in the hopper 2, the powder falls onto the lower inclined flat plate 4 from the long narrow leakage opening at the lower end of the hopper 2, the powder slides along the inclined flat plate 4, the sliding speed of the spherical powder is high, and the sliding speed of the irregular powder is low;

(3) when the powder falls on the horizontal table top 6 below the inclined flat plate 4, the kinetic energy of the spherical powder particles is larger, and the spherical powder particles continue to move forward and fall into the material receiving tank 7 below the horizontal table top 6; the kinetic energy obtained by the irregular powder particles or the powder particles with poor sphericity on the inclined flat plate 4 is not large enough, so that when the irregular powder particles or the powder particles with poor sphericity fall on the horizontal table top 6, the kinetic energy is reduced until the kinetic energy is zero, and the irregular powder particles or the powder particles with poor sphericity stay on the horizontal table top 6;

(4) the spherical powder receiving tank 7 is moved away, another receiving tank 7 for receiving irregular powder is replaced, the inclined flat plate 4 and the horizontal table surface 6 are tapped by a tool, and the brush is used for sweeping lightly, so that the irregular powder falls into the irregular powder receiving tank 7;

(5) and (4) replacing the spherical powder receiving tank 7, and starting from the step (1).

The principle of separating and removing irregular powder particles is as follows:

when the spherical powder particles and the irregular powder particles roll on the surface of the inclined flat plate 4, because the spherical powder particles and the inclined flat plate 4 are in point contact, the resistance generated between the spherical powder particles and the slope is small, the kinetic energy is gradually increased under the action of the gravity of the particles along the inclined plane direction of the inclined flat plate 4, and when the particles touch an obstacle or fall on a horizontal end surface, the particles can continuously roll forward under the drive of the original kinetic energy and fall off the horizontal end surface 6; for the irregular powder particles, because the contact surface between the particles and the inclined flat plate 4 is large, large resistance is generated, the irregular powder particles may stay on the inclined flat plate 4 and may also continue to slide down along the slope, but because the kinetic energy is small, when the irregular powder particles touch an obstacle or fall on the horizontal table top 6, the driving force of the original kinetic energy is not enough to enable the irregular powder particles to continue to advance or leave the horizontal table top 6. Therefore, irregular particles can be removed from the spherical powder, thereby improving the flowability of the powder particles.

When the powder particles start from the top position of the inclined flat plate and reach the tail end of the horizontal table top 6, the kinetic energy expression of the powder particles is as follows:

E＝1/2mv²＝mgL₁sinθ-u₁mgL₁cosθ-u₂mgL₂-E₁。

wherein E is kinetic energy, m is mass of particles, v is velocity, g is acceleration of gravity, and L is₁For the length of the inclined plate, theta is the inclination of the inclined plate, L₂Is the length of the horizontal table surface u₁And u₂Are respectively provided withCoefficient of friction of particles on inclined plates or horizontal tables, E₁Is the energy loss of the particles as they leave the inclined plate to the horizontal table.

Due to the coefficient of friction u of the spherical powder particles and the irregular powder particles on the inclined flat plate 4 or the horizontal table 6₁And u₂Is different, because the contact surface between the irregular powder particles and the inclined flat plate 4 is larger, the friction coefficient of the irregular powder particles is larger in the flowing process, and the energy loss E is reduced₁The irregular powder particles are relatively large, and the moving distance of the irregular powder particles on the inclined flat plate and the horizontal table top is short, so that the purpose of removing the irregular powder particles from the spherical powder is achieved.

In one embodiment of the invention, the length L of the inclined plate₁Length L of the horizontal table-board₂The following relationships are required: said L₁/L₂The value range of (A) is 8-20, preferably 10-15.

In the following examples, the flowability of the spherical powder was measured by using a Hall flow meter and GB/T1482-2010 test method.

Example 1

(1) NiTi spherical powder (with the average grain diameter D50 of 53-250 microns) is used as a raw material, and as can be seen from figure 2, the raw material contains irregular particles and spherical particles;

(2) the device shown in fig. 1 is adopted, the length L1 of the inclined flat plate is 260mm, the inclination theta is 36 degrees, the horizontal table surface L2 is 20mm, and the powder feeding gap D of the hopper is 2.5 mm;

(3) 50g of NiTi spherical powder serving as a raw material is quantitatively filled into a hopper by a spoon, the powder is spread in the hopper and falls onto a lower inclined flat plate from a long narrow leakage opening at the lower end of the hopper, the powder slides onto a horizontal table surface along the inclined flat plate and falls into a material receiving tank, and a small amount of powder is left on the inclined flat plate and the horizontal table surface;

(4) moving the spherical powder receiving tank away, replacing the other receiving tank for receiving the irregular powder, tapping the inclined flat plate and the horizontal table surface by a tool, and lightly sweeping by a brush to enable the irregular powder to fall into the irregular powder receiving tank;

(5) replacing the spherical powder receiving tank again, and repeating the steps (1) to (4);

(6) after the treatment amount reaches 1000g, 913.4 g of powder in the spherical powder receiving tank and 86.1 g of powder in the irregular powder receiving tank are weighed; it was found by calculation that the content of irregular particles in the NiTi spherical powder was 8.61 wt%.

Scanning electron microscope is adopted to respectively observe NiTi spherical powder before treatment, NiTi spherical powder after irregular particle removal and irregular particle removal in a microscopic way, as shown in figure 2, figure 3 and figure 4.

The flowability of the NiTi spherical powder before treatment and after removal of irregular particles was measured respectively and shown in Table 1, the flowability of the powder before treatment was 31.48s/50g, and the flowability parameter after removal of irregular particles was better and reached 28.72s/50 g.

Table 1: results of changes in flowability of powders before and after treatment of examples 1 to 3 and comparative example 1

	Fluidity before treatment was s/50g	Fluidity after treatment was s/50g
			Example 1	31.48	28.72
Example 2	34.24	26.38
			Example 3	20.23	19.10
Comparative example 1	31.48	29.98

Example 2

This example was the same as example 1 except that the inclination θ of the inclined plate was adjusted to 70 °, and the spherical powder treated was TC4 spherical powder (average particle diameter D50 was 15 to 53 μm).

The irregular particle content in the spherical powder of TC4 was calculated to be 20.10 wt% after treatment. The flowability results of the TC4 spherical powder before and after treatment were tested separately and are shown in table 1. As a result, the flow of TC4 spherical powder was improved to 34.24s/50g before treatment and to 26.38s/50g after treatment.

Taking the TC4 spherical powder before and after the processing in this embodiment, SLM 3D printing entities were respectively performed by using an M100 laser 3D printer developed by itself under the same conditions (laser power 170W, pulse duty ratio 80%). The density of the TC4 spherical powder before treatment without removing the irregular particles is 99.3% after printing, and the density of the TC4 spherical powder after treatment with removing the irregular particles is 99.8% after printing. Therefore, TC4 spherical powder without irregular particles is poor in flowability, loose density is reduced, powder filling density is low in the SLM 3D printing and powder laying process, air holes are easy to form, air hole defects exist after printing, density is reduced, and mechanical strength of the material is affected finally.

Example 3

This example is the same as example 1 except that the slope θ of the slope of the inclined plate was adjusted to 20 °, the horizontal table L2 was adjusted to 30mm, and the spherical powder treated was zirconia spherical powder (average particle diameter D50 was 150 μm).

The irregular particle content in the zirconia spherical powder was calculated to be 5.30% after treatment.

The flowability results of the zirconia spherical powder before and after the treatment were measured separately and are shown in table 1. From the results, it was found that the flowability of the spherical zirconia powder was improved to 20.23s/50g before the treatment and 19.10s/50g after the treatment.

Comparative example 1

This comparative example is identical to the process of example 1, except that the inclined plate length L1 is 200mm, L2 is 30mm, i.e., L1/L2 is 6.67.

FIG. 5 is a scanning electron microscope image of the NiTi spherical powder of this comparative example after removing irregular particles. From the results of FIG. 5, it is understood that a small amount of irregular particles are still mixed in the NiTi spherical powder after removal by the apparatus of this comparative example.

The content of irregular particles in the NiTi spherical powder was calculated to be 7.35 wt% after the treatment (the experimental result should be less than 8.61 wt% of example 1). Respectively testing the NiTi spherical powder before and after the irregular particles are removed, wherein the flowability is shown in table 1, and the flowability of the powder before treatment is 31.48s/50 g; the flowability after removal of the irregular particles was 29.98s/50g, and the flowability of the NiTi spherical powder after removal of the irregular particles of this comparative example was inferior to that of example 1.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.