阅读说明：本技术 一种可同时提升成型精度和成型效率的增材制造方法 (Additive manufacturing method capable of simultaneously improving forming precision and forming efficiency ) 是由 陈东菊 王朋 李港 范晋伟 田汉青 于 2021-08-29 设计创作，主要内容包括：本发明公开了一种可同时提升成型精度和成型效率的增材制造方法,各零件单元由三维建模软件设计制作并满足装配条件后导入装配分层软件,各零件单元在切片分层软件中完成处理。经分层软件导出的文件导入AM设备,完成送粉、铺粉等操作,高能量激光束按照当前层数据信息选择性地熔化基板上的粉末,成型出零件当前层形状,而后基板下移、水平刮板归位,一轮扫描结束。在该层扫描过程中各零件可采用不同的工艺参数和成型策略,以最大限度调整和优化成型试件。直至整个零件按照预定数据信息成型并完成制造。本发明操作简单,可依据不同的结构采用不同的成型策略,极大提升AM成型试件的成型精度和成型效率,达到精度和效率兼顾的目的。(The invention discloses an additive manufacturing method capable of simultaneously improving molding precision and molding efficiency. And (3) importing the file exported by the layering software into AM equipment to finish the operations of powder feeding, powder spreading and the like, selectively melting the powder on the substrate by using a high-energy laser beam according to the data information of the current layer to form the shape of the current layer of the part, then moving the substrate downwards, returning the horizontal scraper and finishing one-round scanning. In the scanning process of the layer, different process parameters and forming strategies can be adopted for each part so as to adjust and optimize the formed test piece to the maximum extent. Until the whole part is shaped according to the predetermined data information and the manufacture is finished. The AM forming device is simple to operate, different forming strategies can be adopted according to different structures, the forming precision and the forming efficiency of the AM forming test piece are greatly improved, and the purpose of considering both the precision and the efficiency is achieved.)

1. The additive manufacturing method capable of simultaneously improving the forming precision and the forming efficiency is characterized in that each part unit of an assembly-free mechanism is designed and manufactured by three-dimensional modeling software, assembly layering software is introduced after assembly conditions are met, and assembly, parameter setting, layering and other processing are completed in slicing layering software by each part unit. And (3) guiding the file exported by the layering software into metal additive manufacturing equipment to finish the operations of powder feeding, powder spreading and the like, selectively melting the powder on the substrate by using a high-energy laser beam according to the data information of the current layer to form the shape of the current layer of the part, then moving the substrate downwards, returning the horizontal scraper, and finishing one-round scanning. In the scanning process of the layer, different process parameters and forming strategies can be adopted for each part so as to adjust and optimize the formed test piece to the maximum extent. The high energy laser beam then selectively melts the powder according to the next layer of model data information. And repeating the steps until the whole part is molded according to the preset data information and the manufacturing is finished.

2. The additive manufacturing method capable of simultaneously improving the forming accuracy and the forming efficiency as claimed in claim 1, wherein the forming method can adopt the process parameters with good quality, high accuracy and low forming efficiency at some parts of the assembly-free mechanism, and can adopt the process parameters with quality and accuracy meeting the requirements and high forming efficiency at other parts.

3. The additive manufacturing method capable of simultaneously improving the molding precision and the molding efficiency as claimed in claim 1, wherein the same component is of a solid structure, a porous structure, a suspension structure, a thin-wall structure and a microarray structure by adopting different molding processes, thereby achieving the purpose of precise molding.

4. The additive manufacturing method according to claim 1, wherein the forming precision and the forming efficiency are improved simultaneously, and the method comprises the following steps: the forming method of different process parameters and scanning strategies is adopted for implementing different partition structures of the same assembly part, so that the forming efficiency of the assembly part can be improved on the basis of ensuring the forming precision and the mechanical property of the part, and the purpose of high-quality and high-efficiency forming is achieved.

Technical Field

The invention relates to an additive manufacturing method capable of simultaneously improving molding precision and molding efficiency, and belongs to the field of additive manufacturing.

Background

Additive Manufacturing (AM) is a rapid prototyping technology with a wide development prospect, and is widely applied to the fields of aerospace, automobile manufacturing, medical treatment, industrial product design, building design, entertainment products, biotechnology, and the like. Different from traditional material reduction processing and equal material processing, the AM technology utilizes high-energy laser beams to melt metal powder, parts can be quickly formed without cutters, clamps and dies, the production period is short, and the material utilization rate is high. The AM technology can be used for directly producing metal parts with excellent metallurgical bonding, high density, excellent mechanical property, high dimensional precision and excellent surface quality. Compared with the traditional machining technology, the AM can be used for forming any complicated metal part without limiting the shape of the part. It has obvious advantages in the aspects of metal materials which are difficult to machine by the traditional process and parts with complex structures.

The metal powder particles are melted to form a molten pool and rapidly solidify in a short time (typically tens of microseconds). The AM formation process involves microscopic-mesoscopic-macroscopic and is a cross-scale formation. The powder size is generally about tens of microns, and the laser spot size is generally about 70 microns. As shown in fig. 2, AM is based on the forming theory that the melt pools are connected into melt channels, the melt channels are overlapped into planes, and the planes are stacked into a part body, and the forming efficiency is general. In addition, the complexity of the forming process and the instability of the forming process can cause factors such as holes, splashing, spheroidization, poor texture and mechanical properties, residual stress and the like in the test sample. Therefore, accurate control of the process parameters is a prerequisite for ensuring the molding quality. However, the accurate control of the molding process parameters is based on the premise of sacrificing the molding efficiency, and the molding efficiency and the molding accuracy cannot be considered in the current molding process.

Disclosure of Invention

The invention aims to solve the problem of providing an additive manufacturing method giving consideration to both forming efficiency and forming precision.

Based on the existing SLM forming technology, the invention can develop novel SLM layering software and also can utilize the existing layering software to carry out the assembly and layering design of parts, and is necessary to ensure the development of the novel layering assembly software for forming quality.

SLM forming is not limited by complexity of parts, and theoretically parts with any complex structures can be formed. Therefore, the part design idea can break through the traditional design method. The invention adopts the idea of partition modeling integrated molding and utilizes three-dimensional design software to carry out three-dimensional partition modeling design on parts to be molded. The design is divided into an accurate forming area and an efficient forming area, wherein the accurate forming area is a key core area of the part, and the forming performance of the part is guaranteed in a key mode; the efficient forming area is a non-key part of the part, and the forming efficiency of the part is mainly improved in the area.

And respectively exporting STL format files from the designed partitioned part models, then importing the STL format files into assembly layered software, and assembling the partitioned parts in the assembly layered software.

The STL format files of different partitions are imported into the assembly layering software to be layered and set process parameters according to different parts, so that the parameters of different partitions of the assembled parts can be set respectively. The process parameters that can be set for the parts of different partitions are (layer thickness, laser power, scanning speed, dot pitch, exposure time, line pitch, etc.) and scanning strategies (line scanning, bar scanning, checkerboard scanning, boundary strategies, contour strategies, upper surface strategies, remelting strategies, etc.). The purpose that the same assembly body adopts different forming parameters and strategies is achieved by setting different process parameters and scanning strategies for parts in different partitions. The accurate forming area adopts a strategy of reducing scanning speed and increasing remelting so as to improve forming accuracy and mechanical property; the high-efficiency forming area adopts the strategies of improving the scanning speed and reducing the auxiliary strategies to improve the forming efficiency.

And (4) guiding the assembly body which is layered and is subjected to process setting into SLM equipment, and performing additive manufacturing and integrated molding. The SLM integrated forming step comprises:

and a homologous material substrate is selected to ensure the homologous wettability of the spreading behavior of the SLM molten pool. The metal substrate was subjected to sand blasting and alcohol wiping treatment, and the powder was dried.

And mounting the processed substrate into an SLM working cabin, and performing pre-powder spreading to verify the flatness of the substrate.

And (3) sealing and forming a cabin body, vacuumizing, and introducing protective gas (inert gases such as argon, nitrogen, helium and the like) into the cabin body.

And starting SLM forming when the oxygen concentration in the cabin body is reduced to a certain threshold value (generally set to 300 ppm). Firstly, the support structure is formed, residual oxygen in the cabin is consumed, and the oxygen concentration in the forming cabin is strictly ensured. Meanwhile, the support is added, so that the separation treatment of the parts and the substrate in the later period is facilitated.

After the forming of the supporting structure is completed, an assembly body structure is formed. And by continuously reducing the slice height, the laser carries out accurate and efficient molding on the part according to a planned track in the molding layer according to a preset layered scanning strategy.

The invention has the advantages that:

the invention provides a forming method which is implemented on the basis of the current SLM equipment and adopts different process parameters and scanning strategies for different partition structures of the same assembly part, so that the forming efficiency of the assembly part can be improved on the basis of ensuring the forming precision and the mechanical property of the part, and the purpose of high-quality and high-efficiency forming is achieved.

Drawings

FIG. 1 is a flow chart of a high-quality and high-efficiency processing method.

FIG. 2 is a schematic view of a part forming strategy.

FIG. 3 is a sectional view of a machined part.

Fig. 4 is a schematic view of an AM400 molding chamber.

Fig. 5 is a schematic diagram of a high precision forming strategy (boundary strategy and reflow strategy).

The reference numerals in the drawings have the following meanings:

(1) (2) the parts are divided into different areas, (4) the powder chamber, (5) the scraper, (6) the substrate, (7) the inert flowing gas inlet, (8) the inert flowing gas outlet, (9) the powder recovery device, (10) the laser system, and (11) the galvanometer

Detailed Description

The principles and features of this invention are described below in conjunction with the following examples, which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

The equipment used in the embodiment of the invention is Renishaw AM400 equipment, the layering software is QuantAM software, and three-dimensional modeling software is not limited.

1) Three-dimensional software modeling

The model mechanism is investigated, the use range and the working requirement condition of the model mechanism are known, and the whole model is designed in a partitioned manner, as shown in fig. 3. Considering that the structures of the (1) and the (3) are more regular and are efficient forming areas; (2) the structure comprises a complex curved surface, which is an accurate forming area. After (1), (2), and (3) are designed separately ((1) and (3) can also be designed as a whole), the file in STL format is exported.

2) Three-dimensional modeling assembly

And (3) importing the three STL files (1), (2) and (3) into Quantam software, and assembling the model according to the position and the size.

3) Process parameter and scan strategy settings

And (3) setting parameters and scanning strategies for the three imported STL files (1), (2) and (3). Wherein (1) and (3) are used as solid structures, and parameters are set in a mode of high scanning speed and auxiliary scanning strategy reduction under the condition of ensuring the performance. (2) The part is a curved surface structure, and parameters are set by taking low scanning speed, high density and high mechanical property as standards. In order to ensure the use requirement, auxiliary scanning modes such as laser remelting, profile scanning and the like can be added, and the forming performance of the step (2) is improved. Exporting the set model from the MTT format file and importing the set model into the AM400 device.

4) Preparatory work before forming

The powder is screened and dried in a vacuum oven to remove moisture that may be adsorbed on the surface. On the basis of ensuring the evenness of the homologous substrate, the surface is subjected to sand blasting treatment and then is wiped by alcohol, so that the cleanness and tidiness of a forming plane are ensured. And adding the processed powder into the powder cabin, and mounting the forming substrate on a forming cabin workbench. And leveling the substrate by adopting a pre-powder laying strategy, and setting a reference. The oxygen threshold was set at 300ppm and the amount of powder leakage (in this case the layer thickness was set at 50 μm, with reference to the actual powder layer thickness).

5) Laser forming

And (3) AM400 is firstly vacuumized and treated by injecting argon, inert gas enters from (7) and is discharged from (8), the circulation is carried out for a plurality of times, the set oxygen threshold is reached, and laser processing is started. The inert gas keeps (7) in and out of the circulating flow in the laser processing process so as to blow away impurities generated by splashing. (6) And (3) descending by the thickness of one slice, sending the powder in the step (4) to a powder spreading mechanism before the step (5), and spreading the powder on a step (6) by the powder spreading mechanism to obtain a powder thin layer with the layer thickness of 50 mu m on the step (6). In order to consume the residual oxygen in the forming cabin and facilitate the separation of the later-stage parts from the substrate, the support is firstly printed.

After the printing of the several layers of support is completed, the residual oxygen is almost consumed and the oxygen content drops below 1 ppm. When the parts are molded, the oxygen content is kept below 1 ppm. During the forming process, (10) and (11) of the AM400 device are matched with the powder in the regions (1), (2) and (3) which are respectively processed according to different process parameters. The high energy laser beam selectively melts the powder according to the slice information, (2) zone-increasing boundary scan (as shown in fig. 5 a) and laser remelting (as shown in fig. 5 b), etc., to process the part at a low scan speed. (1) And (3) zone selective melting of the powder using a higher scan speed.

After the current layer is processed, the workbench descends by one powder layer height, and the laser beam selectively melts the powder in the areas (1), (3) and (2) according to the slicing information of the next layer by adopting different process parameters. And the steps are repeated in a circulating way until the processing is finished.