阅读说明：本技术 一种提高增材制造中粉床性能和铺粉效率的刮板形状设计 (Scraper shape design for improving powder bed performance and powder laying efficiency in additive manufacturing ) 是由 安希忠 吴琼 付海涛 张�浩 杨晓红 邹清川 于 2021-07-21 设计创作，主要内容包括：本发明涉及一种提高增材制造中粉床性能和铺粉效率的刮板形状设计,用于实现在较低铺粉高度和较高铺粉速度下获取堆积密度高、表面粗糙度小且均匀性好的粉末层。该方法将通过直角形刮板底部变形设计,有效解决传统刮板在低铺粉高度和高铺粉速度条件下铺粉质量差的问题,可用于多种粉体的增材制造铺粉过程。同时,该新型刮板在较大范围的操作参数区间均表现出高堆积密度、均匀性及平整度。在满足铺粉质量的前提下,单一工艺参数如铺粉高度可较直角板降低约20％以上,铺粉速度可较直角板提高约200％。该新型刮板具有铺粉质量好,对铺粉工艺条件适应性高等优点,满足了实际增材制造过程中对铺粉效率和铺粉高度的要求。(The invention relates to a scraper shape design for improving powder bed performance and powder laying efficiency in additive manufacturing, which is used for obtaining a powder layer with high bulk density, small surface roughness and good uniformity at a lower powder laying height and a higher powder laying speed. The method effectively solves the problem that the traditional scraper has poor powder paving quality under the conditions of low powder paving height and high powder paving speed through the bottom deformation design of the right-angle scraper, and can be used for the additive manufacturing and powder paving process of various powders. Meanwhile, the novel scraper plate has high stacking density, uniformity and flatness within a large range of operation parameters. On the premise of meeting the powder paving quality, the single process parameter such as the powder paving height can be reduced by more than about 20 percent compared with that of a straight angle plate, and the powder paving speed can be improved by about 200 percent compared with that of the straight angle plate. The novel scraper has the advantages of good powder paving quality, high adaptability to powder paving process conditions and the like, and meets the requirements on powder paving efficiency and powder paving height in the actual additive manufacturing process.)

1. The utility model provides a scraper blade shape design of powder bed performance and shop powder efficiency in improvement additive manufacturing, its characterized in that introduces the design that plane and half cambered surface combined together to right angle shape scraper blade bottom, and the board type design includes following step:

s1, three-dimensional modeling: constructing a 3D model of the scraper device; carrying out grid division on the scraper and smoothing the boundary; simulating the actual powder laying process of the scraper by using a DEM discrete element numerical simulation method;

s2, powder production: generating a certain amount of special 3D printing powder with the particle size distribution of 13-86 mu m before powder spreading, and standing the powder pile on the surface of a substrate;

s3, setting process parameters: setting a reasonable process parameter range according to parameter requirements and relevant literature data in the actual additive manufacturing powder laying process, and ensuring that the set process parameter range comprises low gap height and high powder laying speed;

s4, powder paving: in the protection of argon gas environment, setting the powder spreading speed and the gap height of a design scraper according to the process parameters of S3, and spreading powder under different operation conditions by using the design scraper;

s5, adaptability of process parameters: the method of claim S1, wherein the design blade is compared to the right-angle blade over the same range of operating parameters, and wherein the powder bed performance and powder spreading efficiency of the design blade, and the adaptability to process conditions over a wide range of intervals, are specified by computer simulation.

2. The squeegee design of claim 1, wherein the squeegee height is designed to be 8mm in step S1, and the lower end of the squeegee is composed of a half-arc section and a flat section, wherein the length of the flat section is 0.25mm and the angle of the arc is 15 °.

3. The blade design of claim 1 wherein the powder selected in step S2 is a SLM additive manufacturing laser printer powder with good sphericity and an average particle size distribution of 13 to 86 μm, where D₁₀、D₅₀、D₉₀24 μm, 38 μm and 60 μm, respectively.

4. The design of scraper blade of claim 1, characterized in that in the parameter setting of step S3, the powder spreading speed of the scraper blade used is 0.04-0.16 m/S, and the powder spreading height is 1.50-3.00D₉₀。

5. The squeegee design of claim 1, wherein the gap height and dusting speed of the design squeegee are adjusted in step S4 according to the parameter settings in S3.

6. The squeegee design of claim 1, wherein the right angle squeegees used in step S5 are used with the design squeegees for the same range of process parameters.

7. A blade design according to any one of claims 1-6, characterized in that the powder is a powder used in the actual additive manufacturing printing process.

Technical Field

The invention relates to scraper shape design and application for improving powder bed performance and powder laying efficiency in additive manufacturing, and belongs to the technical field of additive manufacturing.

Background

Additive manufacturing is a technology for manufacturing parts by using three-dimensional model data in a layer-by-layer accumulation mode, has the unique advantages of high forming speed, no redundant waste material during processing, capability of producing parts with precision and complex shapes and the like, and is widely applied to the industry. Wherein, the powder spreading is used as the most basic and important production link, and the quality of the powder bed directly influences the product performance. Therefore, the industry has been demanding to obtain a dense, uniform, and flat powder bed. In the whole printing device for additive manufacturing, the scraper is one of important components of the powder laying link. In actual production, the shape of the scraper used is generally the traditional design of a right-angle plate, as shown in fig. 1, the right-angle scraper pushes the powder pile standing at the upper end of the substrate to move forward at a certain powder spreading speed and a certain gap height, the powder pile enters the bottom of the scraper through the gap between the scraper and the substrate in the process of moving forward, and the scraper continues to move forward until the scraper pushes the powder pile to the tail end of the substrate, the powder pile is gradually reduced, and a powder bed is formed.

As can be seen in connection with fig. 1, the particles have a limited ability to deposit under the right angle blade. According to the related research before, the particles at the front end of the right-angle scraper are influenced by the forward movement of the scraper, and the interaction force among the particles is in an interweaving state, wherein larger interaction force among the particles is connected together through the particles to form a strong arch. When the right-angle scraper moves forwards, the powerful arch is damaged, particles in front of the scraper are damaged by the stressed arch and are pushed away from a particle deposition gap, and limited particles enter the lower end of the right-angle scraper, so that the quality of the powder bed is reduced. This behavior is called the dynamic wall effect, which is due to the design imperfections of the right angle flights themselves. Practice proves that the right-angle scraper used in the prior additive manufacturing can only obtain a compact powder bed at low powder laying speed and high powder laying height, and has strict process conditions and a narrow range; meanwhile, the quality of the powder bed is also influenced by the characteristics of the powder interface, the overall morphology, the particle size distribution and the like. The right-angle scraper is difficult to obtain a powder bed with good quality under the conditions of high powder laying speed and low powder laying height, and the process requirements of high speed and low clearance in the actual additive manufacturing powder laying link cannot be met, so that the development and application of additive manufacturing are limited to a certain extent.

Disclosure of Invention

(I) technical problem to be solved

Aiming at the problem that the right-angle scraper is difficult to meet the requirements of the actual powder spreading link in additive manufacturing on the process parameter interval, the invention provides a feasible right-angle scraper improvement scheme.

(II) technical scheme

In order to achieve the purpose, the invention adopts the main technical scheme that:

1. the utility model provides a scraper blade shape design of powder bed performance and shop powder efficiency in improvement additive manufacturing, its characterized in that introduces the design that plane and half cambered surface combined together to right angle shape scraper blade bottom, and the board type design includes following step:

s1, three-dimensional modeling: constructing a 3D model of the scraper device; carrying out grid division on the scraper and smoothing the boundary; simulating the actual powder laying process of the scraper by using a DEM discrete element numerical simulation method;

s2, powder production: generating a certain amount of special 3D printing powder with the particle size distribution of 13-86 mu m before powder spreading, and standing the powder pile on the surface of a substrate;

s3, setting process parameters: setting a reasonable process parameter range according to parameter requirements and relevant literature data in the actual additive manufacturing powder laying process, and ensuring that the set process parameter range comprises low gap height and high powder laying speed;

s4, powder paving: in the protection of argon gas environment, setting the powder spreading speed and the gap height of a design scraper according to the process parameters of S3, and spreading powder under different operation conditions by using the design scraper;

s5, adaptability of process parameters: the method of claim S1, wherein the design blade is compared to the right-angle blade over the same range of operating parameters, and wherein the powder bed performance and powder spreading efficiency of the design blade, and the adaptability to process conditions over a wide range of intervals, are specified by computer simulation.

As described above for the squeegee design, it is preferable that the height of the squeegee is designed to be 8mm in step S1, and the lower end of the squeegee is composed of a half-arc section and a flat section in which the length of the flat section is 0.25mm and the angle of the arc is 15 °.

As described above in the blade design, preferably, the powder selected in step S2 is a powder for SLM additive manufacturing laser printer, with good sphericity and average particle size distribution of 13-86 μm, wherein D₁₀、D₅₀、D₉₀24 μm, 38 μm and 60 μm, respectively.

In the scraper design, preferably, in the parameter setting of step S3, the powder spreading speed of the scraper is 0.04-0.16 m/S, and the powder spreading height is 1.50-3.00D₉₀。

As with the scraper design described above, it is preferable that the gap height and the powder laying speed of the design scraper in step S4 be adjusted according to the parameter settings in S3.

(III) advantageous effects

The invention has the beneficial effects that:

the invention provides the design and application of the novel scraper by improving the shape of the bottom of the right-angle scraper, the novel scraper not only can form a compact and uniform powder bed structure in a wider process parameter operation interval, but also effectively ensures the quality of the powder bed under the process conditions of higher powder laying speed and lower powder laying height, and the actual production requirements of additive manufacturing are met to the greatest extent. This provides a high quality powder bed for local melting and solidification during subsequent printing, which is beneficial for improving the performance of the final printed product. The design can be widely applied to the powder laying link of additive manufacturing of various materials.

Drawings

FIG. 1 is a schematic view of a right-angle scraper powder spreading process;

FIG. 2 is a schematic diagram of the overall structure of the novel scraper blade designed by the invention applied to additive manufacturing;

FIG. 3 is a schematic view of the novel flight designed according to the present invention;

FIG. 4 is a comparison of powder bed roughness and bulk density after powder scraping with a square plate and a new plate.

FIG. 5 shows the comparison of the average bulk density and the coefficient of variation of the powder bed after powder scraping with a square plate and a novel plate.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

Example 1

As shown in fig. 1, the overall structure of the additive manufacturing equipment comprises a novel scraper, a powder feeder, a lifting platform, a forming part, a powder collector and other devices, additive manufacturing (including a powder laying process) is performed in an argon atmosphere, and the movement of the scraper is controlled by a computer. Before powder spreading, the powder feeder is lifted upwards by a preset height, Ti-6Al-4V powder is fed to the front end of the substrate to form a powder pile, and then the powder is uniformly and compactly spread on the whole substrate by using a novel scraper; and (4) spreading powder on the next layer after solidification by laser printing, and circulating the steps to prepare a final formed part. The powder left after each layer of powder paving can enter the powder collector for recycling. Therefore, the particle size distribution and surface state of the Ti-6Al-4V powder are kept unchanged in the whole additive manufacturing process.

The design selects a first layer of powder laying simulation for analysis, and the simulation working parameters are as follows: the powder spreading speed is 0.04m/s, 0.08m/s, 0.12m/s and 0.16 m/s; powder spreading height: 90 μm, 100 μm, 120 μm, 150 μm, 180 μm. An orthogonal experimental protocol was used for a total of 20 sets of simulated conditions. After the powder bed of one layer is completely laid, a zone Domin (excluding interference factors of the boundary) is selected at the middle position of the powder bed, and the zone Domin is evenly divided into 600 sub-zones for calculating the surface roughness, the stacking density and the uniformity of the powder bed. The results show that: under each operating condition, the novel scraper blade can obtain a right-angle scraper blade with better powder bed surface roughness, stacking density and uniformity. Among them, the difference in bulk density between the two plate types is most significant at low powder-laying height and high powder-laying speed. See fig. 4 and 5 for comparison of right angle flights to novel flight stack performance.

Example 2

The embodiment mainly considers the influence of the plate type on the powder spreading height.

The specific process comprises the following steps: ti-6Al-4V powder with perfect sphericity is used, the particle size distribution is 13-86 mu m, D₉₀60 μm. Setting the powder spreading speed to be 0.04m/s, 0.08m/s, 0.12m/s and 0.16m/s respectively, and performing the powder spreading at each speed to be 1.50D in height respectively₉₀、1.65D₉₀、2.00D₉₀、2.50D₉₀、3.00D₉₀The powder laying process is simulated. The scrapers are selected from right-angle scrapers and novel scrapers. Sub-bins are provided on the upper edge of the substrate at an effective distance from the blade (to ensure powder is stationary) to follow the blade movement for real-time collection of average bulk density and coefficient of variation data. Wherein the average bulk density is used to characterize the powder bed mass; the coefficient of variation is used to characterize the uniformity of the powder bed. The higher the average bulk density, the better the powder bed quality; the smaller the coefficient of variation, the better the powder bed uniformity. The results show that at similar bulk densities, the novel blade can achieve 32%, 24%, 22%, 21% height reductions at powder spreading speeds of 0.04m/s, 0.08m/s, 0.12m/s, 0.16m/s, respectively, compared to the right-angled blade. See FIG. 5 for the results of the average bulk density and coefficient of variation of the powder bed.

Example 3

The embodiment mainly considers the influence of the plate type on the powder spreading speed.

The specific process comprises the following steps: ti-6Al-4V powder with perfect sphericity is used, the particle size distribution is 13-86 mu m, D₉₀60 μm. Setting the spreading height to be 1.50D respectively₉₀、1.65D₉₀、2.00D₉₀、2.50D₉₀、3.00D₉₀(ii) a At each powder spreading speed, the base speed v of the powder spreading was set to 0.04m/s, and the blade speeds were v, 2v, 3v, and 4v, respectively. The scraper is selected from a right-angle scraper and a novel scraper. Sub-bins are provided on the upper edge of the substrate at an effective distance from the blade (to ensure powder is stationary) to follow the blade movement for real-time collection of average bulk density and coefficient of variation data. The results show that the inventive new screed achieves approximately a 200% increase in dusting speed compared to right angle screeds at similar bulk densities. See FIG. 5 for the results of the average bulk density and coefficient of variation of the powder bed.

Example 4

The practical application of the novel scraper in the additive manufacturing process is mainly considered in the embodiment.

The specific process comprises the following steps: the actual additive manufacturing process puts demands on flexible production. Selecting Ti-6Al-4V additive manufacturing powder for actual production, and simulating a powder paving process by using a right-angle scraper and a novel scraper. Wherein the sphericity of Ti-6Al-4V powder is intact, the powder spreading speed is set as V, 2V, 3V, 4V (V is 0.04m/s), and the powder spreading height is set as 1.50D₉₀、1.65D₉₀、2.00D₉₀、2.50D₉₀、3.00D₉₀(D₉₀60 μm). And acquiring the bulk density of the powder bed after powder spreading. The region with a powder bed bulk density of 0.45 and above 0.45 was selected as the working interval that could satisfy 3D printing. The result shows that the working range of the novel scraper is expanded by about 2.5 times compared with a right-angle plate type scraper, and the working range of the novel scraper is expanded to the direction of lower powder laying height and higher powder laying speed. For the novel scraper, when the powder spreading speed is the fastest speed of 4v, the powder spreading height is equal to 2.50D₉₀The working interval that the stacking density is higher than 0.45 can be achieved; when the powder spreading speed is v, the powder spreading height is equal to 1.65D₉₀The working range with the stacking density higher than 0.45 can be achieved. In comparison, the right-angle scraper cannot reach 0.45 bulk density at the fastest powder spreading speed of 4 v; while the powder spreading height of 2.50D is required for reaching 0.45 bulk density at the powder spreading speed v₉₀. See FIG. 5 for the results of the average bulk density and coefficient of variation of the powder bed.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and not to limit the spirit and scope of the present invention. Without departing from the design concept of the present invention, any simple modification, equivalent change and modification made by the technical personnel in the field to the technical scheme of the present invention, including the angle of the half arc section at the bottom of the scraper, the length of the half arc section, the length of the plane section, etc., shall fall into the protection scope of the present invention, and the technical content of the present invention which is claimed is fully recorded in the claims.