阅读说明：本技术 同轴送粉增材制造工艺过程原位观测系统及测试方法 (In-situ observation system and test method for coaxial powder feeding additive manufacturing process ) 是由 王浩伟 罗升 王洪泽 吴一 廉清 孙华 韩静韬 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种同轴送粉增材制造工艺过程原位观测系统及测试方法；该系统包括X射线产生装置,同轴送粉增材制造设备,X射线观测装置；通过在同轴送粉增材制造设备外搭设X射线产生装置,使用X射线对准所需观测进行同轴送粉增材制造工艺过程的位置,通过光学仪器成像,可以观测同轴送粉增材制造工艺过程中金属粉末熔化、匙孔形成、气孔和飞溅演化过程,并通过加入钨粉等高熔点颗粒作为示踪粒子的粒子图像测速法,来追踪熔池内部的流动细节,通过分析热输入量的变化对于熔池动态特征演化的影响规律以及建立激光参数与熔池动态特征以及缺陷演化的映射数学模型,从而获得无缺陷的同轴送粉增材制造参数区间。(The invention discloses an in-situ observation system and a test method for a coaxial powder feeding additive manufacturing process; the system comprises an X-ray generating device, coaxial powder feeding additive manufacturing equipment and an X-ray observing device; the method comprises the steps of setting an X-ray generating device outside a coaxial powder feeding additive manufacturing device, aligning the position of a coaxial powder feeding additive manufacturing process to be observed by using X-rays, imaging by using an optical instrument, observing the evolution processes of metal powder melting, keyhole formation, air hole and splashing in the coaxial powder feeding additive manufacturing process, tracking the flow details inside a molten pool by using a particle image velocimetry method in which high-melting-point particles such as tungsten powder and the like are added as tracer particles, analyzing the influence rule of the change of heat input on the dynamic characteristic evolution of the molten pool, and establishing a mapping mathematical model of laser parameters, the dynamic characteristic of the molten pool and defect evolution, thereby obtaining a defect-free coaxial powder feeding additive manufacturing parameter interval.)

1. An in-situ observation system for a coaxial powder feeding additive manufacturing process is characterized by comprising:

a. a coaxial powder-feeding additive manufacturing device,

comprises a powder supply device (10-4), wherein tracer particles (20-4) are added into the powder of the powder supply device (10-4);

b. an X-ray observation device is arranged on the X-ray observation device,

the X-ray imaging system comprises an X-ray light source (20-1) and an optical path system, wherein the optical path system comprises a reflecting mirror (20-7), a collimating lens (20-8), a focusing mirror (20-9) and an imaging device (20-10);

an X-ray (20-1) light source is aligned with a to-be-processed area (20-3) on a substrate (20-5); after passing through the quasi-processing area (20-3), the X-ray (20-1) passes through an X-ray scintillation counter (20-6) to a reflector (20-7), then to a collimating lens (20-8), a focusing lens (20-9) and finally to an imaging device (20-10);

c. an image display processing device (30),

image data information is acquired through the optical path system, and the data is transmitted to the image display processing equipment (30).

2. The in-situ observation system for the coaxial powder feeding additive manufacturing process according to claim 1, wherein the coaxial powder feeding additive manufacturing equipment further comprises a laser (10-1) and a laser emitter (10-3); the laser (10-1) is connected to the laser transmitter (10-3) through an optical fiber (10-2); the powder supply device (10-4) is aligned with the processing area (20-3), and the powder supply device (10-4) is disposed above the substrate (20-5).

3. The in-situ observation system for the coaxial powder feeding additive manufacturing process according to claim 1, further comprising an X-ray generating device, wherein the X-ray generating device is a synchrotron radiation X-ray generating device.

4. The in-situ observation system for coaxial powder feeding additive manufacturing process according to claim 1, wherein the powder is selected from metal-based powders.

5. The in-situ observation system for the coaxial powder feeding additive manufacturing process according to claim 4, wherein the metal-based powder is selected from one or more of aluminum alloy powder, titanium alloy powder and magnesium alloy powder.

6. The in-situ observation system for the coaxial powder feeding additive manufacturing process according to claim 4, wherein the volume proportion of the tracer particles (20-4) in the metal powder is between 1% and 5%, the melting point of the tracer particles is higher than the boiling point of the metal powder, and the tracer particles do not react with the metal powder.

7. The in-situ observation system for the coaxial powder feeding additive manufacturing process according to claim 6, wherein the particle diameter of the tracer particles (20-4) is between 10 and 100 μm.

8. The in-situ observation system for coaxial powder feeding additive manufacturing process according to claim 1, wherein the size of the substrate (20-5) is a size not exceeding the penetration capability of X-rays and not exceeding 100mm in the direction perpendicular to the X-rays.

9. The in-situ observation system based on the coaxial powder feeding additive manufacturing process according to claim 1, wherein an observation window (20-2) arranged between the X-ray and the quasi-processing area (20-3) is made of a polyimide material and has a thickness not exceeding 10 mm.

10. The test method for in-situ observation of the coaxial powder feeding additive manufacturing process according to the observation system of any one of claims 1 to 9, wherein the method comprises the following steps:

step one, providing the coaxial powder feeding additive manufacturing equipment, setting process parameters to enable the coaxial powder feeding additive manufacturing equipment to work normally, and adding tracer particles (20-4) into metal powder of a powder supply device (10-4) to enable the tracer particles to be uniformly mixed with the metal powder;

starting the X-ray observation equipment, aligning an X-ray light source (20-1) to a machining area (20-3) to be observed, setting parameters and debugging the equipment, and enabling the equipment to enter a working state;

starting the coaxial powder feeding additive manufacturing equipment, starting the additive manufacturing process, and printing a sample;

and step four, after the sample is printed and the process is finished, closing the coaxial powder feeding additive manufacturing equipment, closing the X-ray observation equipment, and processing data information by using image information acquired by the image display processing equipment (30).

Technical Field

The invention belongs to the technical field related to additive manufacturing, and relates to an in-situ observation system and a test method for a coaxial powder feeding additive manufacturing process; the device is suitable for observing the metal powder melting, keyhole forming, air hole and splashing evolution processes and the flowing condition in the molten pool in the coaxial powder feeding additive manufacturing process of various materials under different process parameters.

Background

The coaxial powder feeding additive manufacturing technology is high in machining precision, high in machining efficiency and short in product development period, is gradually applied to customized production of parts with complex shapes, and has wide application prospects in the field of aerospace.

In the coaxial powder feeding additive manufacturing process, high-power-density laser irradiates on metal powder, the metal powder absorbs laser energy and then is rapidly melted and vaporized to form a concave liquid molten pool, and the liquid molten pool moves downwards under the action of evaporation back flushing pressure to form a metal steam hole (keyhole). Because the liquid molten pool and the keyhole are surrounded by surrounding solid metal, the dynamic evolution mechanism of the molten pool and the keyhole under the laser irradiation is not clear, the flow characteristic in the molten pool is not clear, defects are easily introduced in the process, the performance of parts is influenced, and no good observation method or means exist at present, so that the research and development of the coaxial powder feeding additive manufacturing process are limited.

The important difference between the coaxial powder feeding additive manufacturing process and the selective laser melting process is the powder transmission mode, the coaxial powder feeding additive manufacturing process depends on the real-time powder transmission of a powder feeder, and the selective laser melting process mainly comprises powder paving, so that the dynamic powder deposition of the coaxial powder feeding additive manufacturing process causes the process to generate obvious difference with a molten pool manufactured by laser welding and selective laser melting additive manufacturing, and the evolution rule of the molten pool flow, air holes and defects also changes obviously. The laser power is very high, the transferred powder is a dynamic process, the action process of the laser and the powder is more complex, the flow inside the molten pool is more violent and complex, the method belongs to a process of multi-physical-field coupling, and defects are easily introduced, so that the method is more critical to the observation of the flow details inside the molten pool. At present, for the observation of the defects, most of the methods use a sample method to watch a metallographic phase, dynamic observation cannot be carried out in an in-situ observation mode, the flow condition inside a molten pool can be observed, quantitative analysis cannot be carried out, or the condition inside the molten pool can be hardly observed by using a high-speed camera method.

The invention provides an in-situ observation system and a test method for a coaxial powder feeding additive manufacturing process, which combines a particle image velocimetry method of adding high-melting point tracer particles in metal powder by an X-ray observation technology, can directly observe the melting, keyhole forming, air hole and splashing evolution processes of the metal powder in the coaxial powder feeding additive manufacturing process, can track the flow details in a molten pool and the movement behaviors of fluid at defect interfaces such as the air hole and the like by observing the movement behaviors of the tracer particles through X-rays, can quantify the movement speed and other parameters, can conveniently combine a numerical simulation method to quantitatively analyze the defect forming mechanism of the coaxial powder feeding additive manufacturing technology, can quantitatively analyze the influence rule of the change of heat input quantity on the dynamic characteristic evolution of the molten pool and establish laser parameters and dynamic characteristics of the molten pool, and a mapping mathematical model of defect evolution, thereby obtaining a defect-free coaxial powder feeding additive manufacturing parameter interval.

Disclosure of Invention

Aiming at the improvement requirement of the prior art, the invention provides an in-situ observation system and a test method for a coaxial powder feeding additive manufacturing process based on an X-ray imaging technology; the device is suitable for observing the metal powder melting, keyhole forming, air hole and splashing evolution processes and the flowing condition in the molten pool in the coaxial powder feeding additive manufacturing process of various materials under different process parameters.

The purpose of the invention is realized by the following technical scheme:

in a first aspect, the present invention relates to an in-situ observation system for a coaxial powder feeding additive manufacturing process, the observation system comprising:

a. a coaxial powder-feeding additive manufacturing device,

comprises a powder supply device 10-4, wherein tracer particles 20-4 are added into the powder of the powder supply device 10-4;

b. an X-ray observation device is arranged on the X-ray observation device,

the X-ray imaging system comprises an X-ray light source 20-1 and a light path system, wherein the light path system comprises a reflecting mirror 20-7, a collimating lens 20-8, a focusing mirror 20-9 and an imaging device 20-10;

the X-ray light source 20-1 is aligned to a processing area 20-3 on the substrate 20-5, and after passing through the processing area 20-3, the X-ray passes through an X-ray scintillation counter 20-6 to a reflector 20-7, then to a collimating lens 20-8, a focusing mirror 20-9 and finally to an imaging device 20-10;

c. the image display processing device 30 is provided with,

the image data information is acquired through the optical path system, and the data is transferred to the image display processing device 30.

The in-situ observation system realizes effective integration, the X-ray observation equipment is arranged in front of a printing area of the additive manufacturing equipment, after parameters are adjusted, an X-ray light source is aligned to an additive manufacturing process area to be observed, namely a processing area 20-3, high-melting-point tracer particles 20-4 are added into metal powder, the parameters of the additive manufacturing equipment are set, a coaxial powder feeding additive manufacturing process is started, the details of metal powder melting, keyhole forming, air hole and splashing evolution and molten pool flowing in the coaxial powder feeding additive manufacturing process are collected, and data information is processed in the image display processing equipment 30.

The coaxial powder feeding additive manufacturing equipment comprises all equipment using the coaxial powder feeding manufacturing process. As an embodiment of the invention, the coaxial powder feeding additive manufacturing equipment further comprises a laser 10-1, a laser emitter 10-3; the laser 10-1 is connected to the laser emitter 10-3 through the optical fiber 10-2; the powder supply device 10-4 is aligned with the processing region 20-3 and is disposed above the substrate 20-5.

The material for the coaxial powder feeding additive manufacturing can be aluminum alloy, titanium alloy, magnesium alloy, composite material and other powder materials which can be used for the coaxial powder feeding additive manufacturing process. As an embodiment of the invention, the powder is selected from metal-based powders. The metal powder is selected from one or more of aluminum alloy powder, titanium alloy powder and magnesium alloy powder.

The X-ray generating device in which the X-ray source 20-1 is generated may be any device that can generate X-rays, including synchrotron radiation. As an embodiment of the present invention, the system further comprises an X-ray generating device, which is a synchrotron radiation X-ray generating device, generating an X-ray source 20-1.

The tracer particles 20-4 are particles with a melting point higher than the boiling point of the metal powder and do not react with the metal powder, the volume ratio of the tracer particles 20-4 in the metal powder is 1% -5%, and too much heterogeneous powder interferes with the real movement of the metal liquid in the molten pool, so that too little tracer particles are difficult to observe. As an embodiment of the present invention, the tracer particles 20-4 are selected to have a particle size of 10 μm to 100 μm, which is limited by the resolution of the X-ray observation apparatus and cannot be too small; the particles are too large, the inertia force is too large, and the real flow of the fluid in the molten pool can be influenced.

Wherein the size of the substrate 20-5 generally does not exceed the size of the X-ray transmission capability, generally does not exceed 100mm in the perpendicular X-ray direction. As an embodiment of the present invention, the size of the substrate 20-5 is a size not exceeding the penetration ability of X-rays, and not exceeding 100mm in the direction perpendicular to the X-rays.

Wherein the observation window 20-2 between the X-ray and the coaxial powder feeding additive manufacturing equipment (specifically arranged between the X-ray and the quasi-processing area 20-3) is made of a material which does not cause too much scattering and consumption of light and has a thickness not exceeding 10 mm. As an embodiment of the present invention, the observation window 20-2 between the X-ray and the quasi-processing area 20-3 is made of polyimide material and has a thickness not exceeding 10 mm.

In a second aspect, the invention relates to an in-situ observation and test method for a coaxial powder feeding additive manufacturing process, which is characterized by comprising the following steps:

step one, providing the coaxial powder feeding additive manufacturing equipment, setting process parameters to enable the coaxial powder feeding additive manufacturing equipment to work normally, and adding tracer particles 20-4 into metal powder of a powder supply device 10-4 to enable the tracer particles to be uniformly mixed with the metal powder;

starting the X-ray observation equipment, aligning the X-ray light source 20-1 to the machining area 20-3 to be observed, setting parameters and debugging the equipment to enable the equipment to enter a working state;

starting the coaxial powder feeding additive manufacturing equipment, starting the additive manufacturing process, and printing a sample;

and step four, after the sample is printed and the process is finished, closing the coaxial powder feeding additive manufacturing equipment, closing the X-ray observation equipment, and processing data information by using the image information acquired by the image display processing equipment 30.

And step five, if the process parameters and the materials are changed, repeating the step two, the step three and the step four until the experiment is finished.

Compared with the prior art, the invention has the following beneficial effects:

the in-situ observation system and the test method for the coaxial powder feeding additive manufacturing process provided by the invention realize the observation of the melting, keyhole formation, air hole and splash evolution processes of metal powder and the flow details in the molten pool in the coaxial powder feeding additive manufacturing process, can quantitatively measure the quantitative parameter information such as the flow characteristics, the flow speed and the like in the molten pool in an observation region by adopting a method of adding trace particles and combining X-ray observation, can quantitatively analyze the dynamics and the kinematic characteristics in the molten pool, such as the flow direction, the speed and the like of liquid in the molten pool by combining a numerical simulation technology, and provide a good reference for optimizing a numerical simulation model, thereby providing a solution for a defect generation mechanism and a process optimization scheme in the additive manufacturing process.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic diagram of an in-situ synchrotron radiation observation method for a coaxial powder feeding additive manufacturing process provided by the present invention;

FIG. 2 is an observation schematic diagram of metal powder melting, keyhole formation, air hole and splash evolution processes and flow details inside a molten pool in a coaxial powder feeding additive manufacturing process;

the device comprises a laser 10-1, an optical fiber 10-2, a laser emitter 10-3, a powder supply device 10-4, an X-ray 20-1, an observation window 20-2, a processing area 20-3, tracer particles 20-4, a substrate 20-5, an X-ray scintillation counter 20-6, a reflector 20-7, a collimating lens 20-8, a focusing mirror 20-9, an imaging device 20-10 and image display processing equipment 30.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept. All falling within the scope of the present invention.

Examples

Fig. 1 is a schematic structural diagram of an in-situ observation system in the coaxial powder feeding additive manufacturing process provided by the invention. The system comprises:

the coaxial powder feeding additive manufacturing equipment comprises a laser 10-1, a laser emitter 10-3 and a powder supply device 10-4;

a laser 10-1 connected to the optical fiber 10-2 and connected to the laser emitter 10-3 such that the powder supply device 10-4 is aligned with the processing region 20-3 and disposed above the substrate 20-5; adding tracer particles 20-4 into the powder of the powder supply device 10-4;

the X-ray observation equipment comprises an X-ray light source 20-1 and a light path system, wherein the light path system comprises an X-ray scintillation counter 20-6, a reflecting mirror 20-7, a collimating lens 20-8, a focusing mirror 20-9 and an imaging device 20-10;

an X-ray light source 20-1 is aligned to a processing area 20-3, X-rays pass through a workpiece and then pass through an X-ray scintillation counter 20-6 to a reflector 20-7, a collimating lens 20-8, a focusing lens 20-9 and finally an imaging device 20-10;

the image display processing device 30 is provided with,

the image data information is acquired through the optical path system, and the data is transferred to the image display processing device 30.

In the coaxial powder feeding additive manufacturing equipment, a laser 10-1 can be a blue laser, a red laser and the like, is connected with a laser head (a laser emitter 10-3) through an optical fiber 10-2, a powder supply device 10-4 is integrated with the laser emitter 10-3, and the powder feeding rate, the laser power and the scanning speed are controlled through the coaxial powder feeding additive manufacturing equipment.

The tracer particles 20-4 are uniformly mixed and added into the metal powder in the powder supply device 10-4, so that the metal powder and the tracer particles 20-4 can be simultaneously fed into the processing area 20-3 along with the operation of the powder supply device 10-4 of the coaxial powder feeding additive manufacturing equipment.

The X-ray generating device generates an X-ray 20-1, the X-ray enters the light path system through a coaxial powder feeding additive manufacturing process processing area 20-3 and a substrate 20-5, passes through an X-ray scintillation counter 20-6, reaches a reflector 20-7, then reaches a collimating lens 20-8 and a focusing lens 20-9, and finally reaches an imaging device 20-10. The imaging device 20-10 may be a commercially available imaging device such as an X-ray TDI camera C12200-461 produced by hamamatsu electronics.

The image display processing device 30 acquires image data information through the optical path system, and transfers the data to the image display processing device 30. The image display processing device 30 is a commercially available device capable of acquiring and processing image data information via an optical path system. Such as the OptiPlex 5080 series from Dell corporation.

The embodiment also provides an in-situ observation testing method for the coaxial powder feeding additive manufacturing process based on the X-ray imaging technology, which comprises the following steps:

firstly, setting technological parameters of coaxial powder feeding additive manufacturing equipment to enable the coaxial powder feeding additive manufacturing equipment to work normally, adding 3% of metal tungsten particles with the volume fraction of 30-80 mu m into AlSi10Mg metal powder to enable the metal tungsten particles to be uniformly distributed in the metal powder;

step two, starting synchrotron radiation X-ray observation equipment, aligning a light source to a processing area to be observed, setting parameters and debugging the equipment, enabling the equipment to enter a working state, and acquiring image information;

starting the coaxial powder feeding additive manufacturing equipment, starting the additive manufacturing process, and printing a sample;

and step four, after the sample is printed and the process is finished, closing the coaxial powder feeding additive manufacturing equipment, closing the X-ray related equipment, and using the image information acquired by the image processing equipment.

And step five, if the process parameters and the materials are changed, repeating the step two, the step three and the step four until the experiment is finished.

In the implementation method, the observation system realizes effective integration, and the metal powder melting, keyhole forming, air hole and splashing evolution processes and the flow details in the molten pool in the coaxial powder feeding additive manufacturing process in the additive manufacturing process are observed by adjusting the X-ray observation position and the process parameters of the coaxial powder feeding additive manufacturing process, as shown in figure 2, the scheme can directly observe the metal powder melting, keyhole forming, air hole and splashing evolution processes in the coaxial powder feeding additive manufacturing process, can track the flow details in the molten pool and the flow behaviors of fluids at defect interfaces such as air holes and the like by observing the motion behaviors of tracer particles through X-rays, can quantify the parameters such as motion speed and the like, as the speed distribution of the tracer particles in figure 2, and can conveniently combine a numerical simulation method to quantitatively analyze the defect forming mechanism of the coaxial powder feeding additive manufacturing technology, and the influence rule of the change of the heat input quantity on the dynamic characteristic evolution of the molten pool can be quantitatively analyzed, the laser parameters, the dynamic characteristics of the molten pool and a mapping mathematical model of defect evolution are established, and therefore a defect-free coaxial powder feeding additive manufacturing parameter interval is obtained.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.