Monitoring device and method for laser powder bed melting multi-layer powder laying printing under external field

Abstract

The invention relates to the technical field of laser powder bed melting multi-layer powder laying printing, discloses a monitoring device and method for laser powder bed melting multi-layer powder laying printing under an external field, and particularly discloses a laser emitting assembly used for emitting laser to metal powder to melt the metal powder. The plane image monitoring assembly is used for carrying out image acquisition on the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a plane image; the dynamic image monitoring device is used for carrying out dynamic image acquisition on the interaction process of the metal powder and the laser in the vertical direction of the powder bed groove to obtain a dynamic image; the temperature monitoring device is used for monitoring the temperature change of the surface of the metal powder to form a temperature change image; the external field providing device is used for providing different external field environments for the powder bed groove, and the external field environments comprise a magnetic field and / or an ultrasonic field; the image processing device is used for processing the plane image, the dynamic image and the temperature change image so as to output a monitoring result and improve the printing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of laser powder bed melting multi-layer powder spreading printing, and in particular to a monitoring device and method for laser powder bed melting multi-layer powder spreading printing under an external field. Background Art

[0002] As one of the most mature and widely developed processes in metal additive manufacturing technologies, the selective laser melting technology uses a laser as an energy source and powder as a raw material, and realizes layer-by-layer printing through powder bed powder spreading.

[0003] During the selective laser melting forming process, the powder bed is in an environment of rapid cooling and heating. The molten pool and its surrounding areas experience a process of rapid melting, cooling, and solidification. At the same time, the rapid and repeated thermal cycles will generate a strong temperature gradient, making the chemical state, microstructure, and mechanical properties of the material in a metastable state, thereby causing defects such as cracks, pores, balling, and spattering.

[0004] For the characterization means of defects, currently, mainly the formed parts are analyzed, covering destructive metallographic characterization, non-destructive CT characterization, etc. These characterization means can obtain the defect characteristics, shape, size, and distribution of the formed parts, but lack a dynamic and intuitive analysis of the defect formation mechanism. The online monitoring technology of the forming process can directly observe the changes in the molten pool, temperature field, and the generation process of defects. Currently, there are studies on observing the interaction between the laser and powder, the changes in the molten pool, and the generation of defects through synchrotron radiation X-rays online, but the research mostly focuses on the powder bed in the state of no powder layer or single-layer powder, and does not involve the online monitoring of the multi-layer powder spreading printing process by synchrotron radiation X-rays. In particular, in recent years, the research has focused on the effect of applying external fields such as magnetic fields on printing forming, but the specific influence mechanism of external fields such as magnetic fields on the printing process is not clear. Therefore, it is urgent to develop an advanced device for online monitoring of the evolution of the molten pool structure during laser powder bed melting multi-layer printing under an external field. Summary of the Invention

[0005] The purpose of the present invention is to provide a monitoring device and method for laser powder bed melting multi-layer powder spreading printing under an external field, which is beneficial to subsequent improvement of the printing forming effect and optimization of the additive printing process.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] A monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field, comprising: a printing chamber, a laser emission component, a planar image monitoring component, a dynamic image monitoring device, a temperature monitoring device, an external field providing device and an image processing device that are electrically connected to a controller; a powder bed groove is arranged in the printing chamber, and the powder bed groove is used for laying metal powder; the laser emission component is used for emitting laser to the metal powder to melt the metal powder; the planar image monitoring component is used for collecting images of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain planar images; the dynamic image monitoring device is used for collecting dynamic images of the interaction process between the metal powder and the laser in the vertical direction of the powder bed groove to obtain dynamic images; the temperature monitoring device is used for monitoring the temperature change on the surface of the metal powder to form a temperature change image; the external field providing device is used for providing different external field environments for the powder bed groove, and the external field environment includes a magnetic field and / or an ultrasonic field; the image processing device is used for processing the planar images, the dynamic images and the temperature change images to output monitoring results.

[0008] Preferably, the laser emission component includes a driving device and a laser, the driving device is electrically connected to the controller, and the driving device is used for driving the laser emitted by the laser to move along the extending direction of the powder bed groove to melt the metal powder.

[0009] Preferably, the planar image monitoring component includes an X-ray source, a baffle component and a planar detector. The X-ray beam emitted by the X-ray source sequentially passes through the baffle component, the printing chamber, the metal powder and reaches the planar detector. The planar detector is used for recording the X-ray beam image when the laser melts the metal powder and converting the X-ray beam image into an X-ray beam projection picture.

[0010] Preferably, the dynamic image monitoring device is arranged on the driving device and is arranged in a direction perpendicular to the X-ray beam for monitoring the motion image of the interaction between the laser and the metal powder; the dynamic image monitoring device is a camera.

[0011] Preferably, the temperature monitoring device is an infrared temperature measuring device.

[0012] Preferably, the device further includes a powder feeding component. The powder feeding component is electrically connected to the controller. The powder feeding component includes a motor and a connecting rod. The first end of the connecting rod is located in the printing chamber, and the second end extends out of the printing chamber. The motor is connected to the second end of the connecting rod. A powder feeding funnel is drivingly connected to the connecting rod. The powder feeding funnel is located above the powder bed groove and can reciprocate along the connecting rod to spread powder to the powder bed groove.

[0013] Preferably, the device further includes a powder bed height control device electrically connected to the controller. The powder bed groove includes two symmetrically arranged support plates, and a movable plate disposed between the two support plates and capable of moving up and down relative to the two support plates. The movable plate is connected to a driving rod extending out of the printing chamber, and the driving rod is connected to the powder bed height control device.

[0014] Preferably, the ultrasonic field is formed by the ultrasonic vibration device, and the powder bed height control device is disposed on the ultrasonic vibration device.

[0015] Preferably, a magnet chamber for installing an annular magnet is further disposed at the bottom of the printing chamber, and the annular magnet is used to form the magnetic field.

[0016] The present invention also provides a monitoring method for laser powder bed melting multi-layer powder spreading printing under an external field, including:

[0017] Emitting a laser from a laser emitting component to the metal powder in the powder bed groove in the printing chamber to melt the metal powder;

[0018] Using a planar image monitoring component to collect an image of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a planar image;

[0019] Using a dynamic image monitoring device to collect a dynamic image of the interaction process between the metal powder and the laser in the vertical direction of the powder bed groove to obtain a dynamic image;

[0020] Using a temperature monitoring device to monitor the temperature change on the surface of the metal powder to form a temperature change image; using an external field providing device to provide different external field environments for the powder bed groove, where the external field environment includes a magnetic field and / or an ultrasonic field;

[0021] Using an image processing device to process the planar image, the dynamic image, and the temperature change image to output a monitoring result.

[0022] According to the description of the above solution, the present invention discloses the following technical effects:

[0023] The present invention provides a monitoring device and method for laser powder bed melting multi-layer powder spreading printing under an external field. A planar image monitoring device is used to collect images of the melting process of metal powder in the horizontal direction of the powder bed recess to obtain planar images; a dynamic image monitoring device is used to collect dynamic images of the interaction process between the metal powder and the laser in the vertical direction of the powder bed recess to obtain dynamic images; a temperature monitoring device is used to monitor the temperature change on the surface of the metal powder to form a temperature change image; an external field providing device is used to provide different external field environments for the powder bed recess, and the external field environment includes a magnetic field and / or an ultrasonic field; an image processing device is used to process the planar images, dynamic images and temperature change images to output monitoring results. Such a setting is beneficial to subsequently improving the printing and forming effect and optimizing the additive printing process. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Schematic structural diagram of the monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field provided by the embodiments of this specification;

[0026] Figure 2 Provided by the embodiments of this specification Figure 1 Partial enlarged view of point A in

[0027] Figure 3 Schematic top view of the powder groove provided by the embodiments of this specification;

[0028] Figure 4 Schematic front view of the powder groove provided by the embodiments of this specification;

[0029] Figure 5 Schematic vertical placement diagram of the annular magnet provided by the embodiments of this specification;

[0030] Figure 6 Schematic horizontal placement diagram of the annular magnet provided by the embodiments of this specification;

[0031] Among them, 1. X-ray source; 2. Baffle assembly; 3. Printing chamber; 4. Printing top cover; 5. Air outlet; 6. Infrared transparent window; 7. Air inlet; 8. Ultrasonic vibration device; 9. Powder bed height control device; 10. Front glassy carbon window; 11. Rear glassy carbon window; 12. Powder feeding connection window; 13. Connecting rod; 14. Motor; 15. Planar detector; 16. Infrared temperature measurement device; 17. Laser; 18. Camera; 19. Driving device; 20. Laser; 21. Powder feeding funnel; 22. Powder bed concave platform; 23. Magnet chamber; 24. Movable plate; 25. Boron nitride plate. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] As Figure 1 shown, the embodiment of this specification provides a monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field, including: a printing chamber 3 and a laser emission component, a planar image monitoring component, a dynamic image monitoring device, a temperature monitoring device, an external field providing device, and an image processing device that are electrically connected to a controller; a printing top cover 4 is provided on the top of the printing chamber 3, an air outlet 5 is provided on the printing top cover 4, an air inlet 7 is provided at the bottom of the printing chamber 3, a powder bed groove is provided inside the printing chamber 3, and both ends of the powder bed groove are erected through a powder bed concave platform 22 respectively. The powder bed groove is used for laying metal powder; an infrared transparent window 6 is also provided on the printing top cover 4, and the laser 20 emitted by the laser emission component irradiates the metal powder through the infrared transparent window to melt the metal powder; the planar image monitoring component is used to collect images of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a planar image; the dynamic image monitoring device is used to collect dynamic images of the interaction process between the metal powder and the laser 20 in the vertical direction of the powder bed groove to obtain a dynamic image; the temperature monitoring device is used to monitor the temperature change on the surface of the metal powder to form a temperature change image; the external field providing device is used to provide different external field environments for the powder bed groove, and the external field environment includes a magnetic field and / or an ultrasonic field; the image processing device is used to process the planar image, the dynamic image, and the temperature change image to output a monitoring result. Subsequently, the controller controls the actions of the external field providing device and the laser emission component according to the processing result of the image processing device to optimize the structure of laser powder bed melting multi-layer powder spreading printing under an external field, so as to achieve the purpose of improving the printing forming effect and optimizing the additive printing process.

[0034] The laser emission component includes a driving device 19 and a laser 17. The driving device 19 is electrically connected to the controller. The driving device 19 is used to drive the laser 20 emitted by the laser 17 to move along the extending direction of the powder bed groove, heating the metal powder to melt the metal powder.

[0035] The planar image monitoring component includes an X-ray source 1, a baffle component 2, and a planar detector 15. The X-ray beam emitted by the X-ray source 1 sequentially passes through the baffle component 2, the front glassy carbon window 10 and the rear glassy carbon window 11 provided on both sides of the printing chamber 3, and the metal powder to reach the planar detector 15. The planar detector 15 is used to record the X-ray beam image when the laser melts the metal powder and convert the X-ray beam image into an X-ray beam projection picture. There are multiple baffle components 2, and the multiple baffle components can be arranged horizontally or vertically according to actual needs, such as Figure 1 shown.

[0036] The dynamic image monitoring device is arranged on the driving device 19. The driving device is preferably a driving motor, and the dynamic image monitoring device is arranged in a direction perpendicular to the X-ray beam, used to monitor the motion image of the interaction between the laser and the metal powder; the dynamic image monitoring device is a camera 18.

[0037] The temperature monitoring device is an infrared temperature measuring device 16.

[0038] The device further includes a powder feeding component, as Figures 2 - 3 shown. The powder feeding component is electrically connected to the controller. The powder feeding component includes a motor 14 and a connecting rod 13. The first end of the connecting rod 13 is located inside the printing chamber 3. The connecting rod 13 passes through the powder feeding connection window 12 of the printing chamber 3, and the second end extends out of the printing chamber 3. The motor 14 is connected to the second end of the connecting rod 13. A powder feeding funnel 21 is drivingly connected to the connecting rod 13. The powder feeding funnel 21 is located above the powder bed groove and can reciprocate along the connecting rod 13 to spread powder onto the powder bed groove. The connecting rod 13 and the powder feeding funnel can adopt a lead screw and nut structure widely used in the prior art.

[0039] The device further includes a powder bed height control device 9 electrically connected to the controller, as Figures 3 - 4 shown. The powder bed groove includes two symmetrically arranged support plates, and a movable plate 24 arranged between the two support plates and capable of moving up and down relative to the two support plates. The movable plate 24 is connected to a driving rod extending out of the printing chamber 3, and the driving rod is connected to the powder bed height control device 9. Both support plates are preferably boron nitride plates.

[0040] The ultrasonic field is formed by an ultrasonic vibration device 8, and the powder bed height control device 9 is arranged on the ultrasonic vibration device 8. As Figures 5 - 6As shown, a magnet chamber 23 for installing an annular magnet is further provided at the bottom of the printing chamber 3. The annular magnet is used to form a magnetic field. During the printing process, by introducing a magnetic field or an ultrasonic external field, the flow behavior and structural evolution process of the molten pool can be regulated, the printing forming effect can be improved, and the process can be optimized.

[0041] The present invention also provides a monitoring method for laser powder bed melting multi-layer powder spreading printing under an external field, including:

[0042] Using a laser emitting component to emit a laser to the metal powder in the powder bed groove in the printing chamber 3 to melt the metal powder;

[0043] Using a planar image monitoring component to collect images of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a planar image;

[0044] Using a dynamic image monitoring device to collect dynamic images of the interaction process between the metal powder and the laser in the vertical direction of the powder bed groove to obtain dynamic images;

[0045] Using a temperature monitoring device to monitor the temperature change on the surface of the metal powder to form a temperature change image; using an external field providing device to provide different external field environments for the powder bed groove, and the external field environment includes a magnetic field and / or an ultrasonic field;

[0046] Using an image processing device to process the planar image, the dynamic image and the temperature change image to output a monitoring result.

[0047] The specific usage method of this device is as follows:

[0048] (1) Set the boron nitride plate 25 and the movable plate 24 on the powder bed boss 22, control the height of the movable plate 24 through the powder bed height adjusting device 9 to make it lower than the height of the two boron nitride plates 25 on both sides to form a powder bed groove, spread the metal powder evenly in the powder bed groove, make the powder bed groove located at the laser focus emitted by the laser 17 and consistent with the horizontal movement track of the laser focus, and at the same time, the boron nitride plate 25 and the movable plate 24 are parallel to the front glassy carbon window 10 and the rear glassy carbon window 11, and the powder boss 22 is within the viewing field of the X-ray source 1;

[0049] (2) Turn on the X-ray source 1 and the laser 17. The X-ray beam emitted by the X-ray source 1 irradiates the metal powder horizontally, the laser beam emitted by the laser 17 is focused on the metal powder to melt the metal powder, and the moving speed of the laser beam is controlled by the driving motor. The planar detector 15 records the planar image when the laser beam melts the metal powder, the camera 18 records the moving image of the interaction between the laser beam and the metal powder, and the infrared temperature measuring device 16 records the change of the temperature field on the surface of the metal powder, and stores the planar picture, the moving image of the interaction between the laser beam and the metal powder, and the change of the temperature field on the surface of the metal powder in the computer;

[0050] (3) The powder bed height adjusting device 9 passes through the bottom window of the printing chamber 3 and is connected to the movable plate 24 to control the descending height of the movable plate 24, realizing multi-layer printing with any powder layer thickness;

[0051] (4) The side wall of the printing chamber 3 is connected to the motor 14 through the connecting rod 13. The motor 14 controls the movement of the connecting rod 13. During the movement, the powder leaks onto the movable plate 24 through the powder feeding funnel 21, and at the same time, the bottom surface of the powder feeding funnel 21 levels the powder to realize the powder spreading process;

[0052] (5) Repeat the process of steps (2 - 4) to realize the multi-layer printing process with adjustable layer thickness;

[0053] (6) An annular magnet is installed at the bottom of the printing chamber. By replacing the magnet or rotating the direction of the magnet, printing under any transverse and longitudinal magnetic fields can be realized, and the magnetic field direction can also be adjusted in real time during the printing process;

[0054] (7) The T-shaped powder bed substrate is connected to the ultrasonic oscillation device to realize printing under an ultrasonic field;

[0055] (8) Use image processing software to process all the collected X-ray beam projection pictures, motion pictures, and temperature pictures. Among them, the X-ray beam projection pictures are processed through flat-field correction, artifact correction, and noise removal, and then custom background subtraction is performed to remove non-moving objects, obtaining a set of two-dimensional photos of the powder melting process. Use image processing software to convert a series of two-dimensional photos into a video for storage;

[0056] (9) The controller controls the ultrasonic oscillation device, the arrangement of the annular magnet, and the action of the laser according to the processing results of the image processing software to optimize the structure of laser powder bed melting multi-layer powder spreading printing under an external field.

[0057] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same and similar parts among the embodiments, reference can be made to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and reference can be made to the description in the method part for the relevant parts.

[0058] In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A monitoring device for laser powder bed fusion multi-layer powder spreading printing under an external field, characterized in that Comprising: A printing chamber, a laser emission component, a planar image monitoring component, a dynamic image monitoring device, a temperature monitoring device, an external field providing device, and an image processing device that are electrically connected to a controller; a powder bed groove is provided in the printing chamber, and the powder bed groove is used for laying metal powder; the laser emission component is used to emit laser light towards the metal powder to melt the metal powder; the planar image monitoring component is used to collect images of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a planar image; the dynamic image monitoring device is used to collect dynamic images of the interaction process between the metal powder and the laser in the vertical direction of the powder bed groove to obtain a dynamic image; the temperature monitoring device is used to monitor the temperature change on the surface of the metal powder to form a temperature change image; the external field providing device is used to provide different external field environments for the powder bed groove, and the external field environment includes a magnetic field and / or an ultrasonic field; the image processing device is used to process the planar image, the dynamic image, and the temperature change image to output a monitoring result.

2. The monitoring device for laser powder bed fusion multi-layer powder spreading printing under an external field according to claim 1, characterized in that, The laser emission component includes a driving device and a laser, the driving device is electrically connected to the controller, and the driving device is used to drive the laser emitted by the laser to move along the extending direction of the powder bed groove to melt the metal powder.

3. The monitoring device for multi-layer powder spreading printing by laser powder bed melting under an external field according to claim 2, wherein The planar image monitoring component includes an X-ray source, a baffle component, and a planar detector. The X-ray beam emitted by the X-ray source sequentially passes through the baffle component, the printing chamber, and the metal powder to reach the planar detector. The planar detector is used to record the X-ray beam image when the laser melts the metal powder and convert the X-ray beam image into an X-ray beam projection picture.

4. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 3, wherein The dynamic image monitoring device is arranged on the driving device and is arranged in a direction perpendicular to the X-ray beam, and is used to monitor the motion image of the interaction between the laser and the metal powder; the dynamic image monitoring device is a camera.

5. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 1, characterized in that, The temperature monitoring device is an infrared temperature measurement device.

6. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 1, wherein It further includes a powder feeding component, the powder feeding component is electrically connected to the controller, the powder feeding component includes a motor and a connecting rod, the first end of the connecting rod is located in the printing chamber, the second end extends out of the printing chamber, the motor is connected to the second end of the connecting rod, a powder feeding funnel is drivingly connected to the connecting rod, the powder feeding funnel is located above the powder bed groove and can reciprocate along the connecting rod to lay powder into the powder bed groove.

7. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 1, wherein, It further includes a powder bed height control device electrically connected to the controller. The powder bed groove includes two symmetrically arranged support plates and a movable plate arranged between the two support plates and capable of moving up and down relative to the two support plates. The movable plate is connected to a driving rod extending out of the printing chamber, and the driving rod is connected to the powder bed height control device.

8. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 7, characterized in that, The ultrasonic field is formed by the ultrasonic vibration device, and the powder bed height control device is arranged on the ultrasonic vibration device.

9. The monitoring device for laser powder bed melting multi-layer powder spreading printing under an external field according to claim 1, wherein A magnet chamber for installing an annular magnet is further provided at the bottom of the printing chamber, and the annular magnet is used to form the magnetic field.

10. A monitoring method for laser powder bed fusion multi-layer powder spreading printing under an external field, characterized in that, Including: Emitting a laser from a laser emission component to the metal powder in the powder bed groove in the printing chamber to melt the metal powder; Using a planar image monitoring component to collect an image of the melting process of the metal powder in the horizontal direction of the powder bed groove to obtain a planar image; Using a dynamic image monitoring device to collect a dynamic image of the interaction process between the metal powder and the laser in the vertical direction of the powder bed groove to obtain a dynamic image; Using a temperature monitoring device to monitor the temperature change on the surface of the metal powder to form a temperature change image; Using an external field providing device to provide different external field environments for the powder bed groove, and the external field environments include a magnetic field and / or an ultrasonic field; Using an image processing device to process the planar image, the dynamic image and the temperature change image, To output a monitoring result.

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