Optical systems, devices, and methods for additive manufacturing

Abstract

The present application relates to an optical system, device and method for additive manufacturing, comprising an optical unit configured to generate a laser beam acting on at least a material carried by a printing platform to sinter or melt it, and to control the movement of the laser beam along a preset trajectory to build a three-dimensional object layer by layer; and a lifting device configured to control the lifting of the optical unit in the z-axis direction to cause the focal point of the laser beam to project on the material at different heights. The present application can achieve precise focusing of the light spot at different heights, reduce the occurrence of defocusing effect, and adapt to different printing requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of additive manufacturing, and in particular to an optical system, device and method for additive manufacturing. BACKGROUND

[0002] In conventional additive manufacturing, the focal height of the optical system is usually fixed, which is suitable for a specific printing platform or printing level. However, in actual additive manufacturing applications, different printing levels may require different focal height positions in order to meet different printing requirements, so as to ensure that the light spot can be accurately focused at the required height position.

[0003] For example, in the prior art, the focal length of the laser beam can be adjusted by a field lens to change the height position of the focal point on the z-axis. During the focusing process, the field lens may introduce a defocusing effect of the light beam, which causes the light beam to be unable to maintain focus within a certain distance, thereby causing the focal point not to be at the required height position, and reducing the printing quality. Moreover, during the focusing process, the field lens may introduce optical distortion, which causes abnormal optical effects of the light beam near the focal point, thereby possibly causing uneven energy distribution and distortion.

[0004] Therefore, there is an urgent need in the prior art for an optical system capable of automatically adjusting the height position of the focal point on the z-axis, so that the light spot can be accurately focused at different heights to meet different printing requirements, improve the printing quality, reduce the workload of the operator, and at the same time reduce the adverse effects of optical distortion and defocusing effect on the printing quality. SUMMARY

[0005] In order to automatically adjust the focal height position according to different printing requirements, the present application provides, in a first aspect, an optical system for additive manufacturing, comprising: an optical unit configured to generate a laser beam acting on at least one material carried by a printing platform to sinter or melt the material, and to control the laser beam to move along a preset trajectory to build a three-dimensional object layer by layer; and a lifting device configured to control the optical unit to lift in the z-axis direction to cause the focal point of the laser beam to project on materials at different heights.

[0006] Preferably, the materials at different heights are in the same level or different levels.

[0007] Preferably, the optical system further comprises a control unit for controlling the lifting device to lift according to the printing requirements of the three-dimensional object at different levels, so as to automatically adjust the height position of the focal point on the material.

[0008] Preferably, the printing requirements include at least one of the following factors that are different between the upper layer of material and the lower layer of material: layer thickness, printing path deviation, material properties, layer gap, printing speed.

[0009] Preferably, the printing platform is two, respectively a first printing platform and a second printing platform, wherein the first printing platform and the second printing platform have different heights in the z-axis.

[0010] Preferably, the lifting device is further configured to lift the optical unit in the z-axis, so that the focal point projects on the material of the first printing platform at a first position, and projects on the material of the second printing platform at a second position, wherein the first position and the second position have different heights in the z-axis.

[0011] Preferably, the at least one printing platform is arranged in a printing cabin, and the optical unit is arranged on the cabin top of the printing cabin, and the laser beam emitted by the optical unit is transmitted into the printing cabin through the opening of the cabin top.

[0012] Preferably, the cabin top is lifted in the z-axis under the control of the lifting device, so as to gradually approach or move away from the printing platform.

[0013] Preferably, the material carried by the first printing platform is scanned by the laser beam to form a molten pool, and in the scanning process, the high-energy X-ray is transmitted through the molten pool to diffract imaging, so as to obtain in-situ characterization of the organizational phase in the molten pool; the material carried by the second printing platform is scanned layer by layer by the laser beam to build the three-dimensional object.

[0014] Preferably, the width of the first printing platform is at least the width of the molten pool, and at most 2mm.

[0015] Therefore, the optical system of the present application can automatically adjust the height position of the focal point, so that the light spot can be accurately focused at different heights, adapt to different printing requirements, and improve the printing quality. At the same time, the present application also improves the production efficiency, reduces the work burden of the operator, reduces the occurrence of optical distortion and defocusing effect, and helps to maintain the accurate focusing of the light beam.

[0016] The second aspect of the present application provides an additive manufacturing device, comprising at least one printing platform for carrying materials and the optical system described above.

[0017] Preferably, the additive manufacturing device comprises a high-energy X-ray device for emitting high-energy X-ray transmission molten pool diffraction imaging to obtain in-situ characterization of the organizational phase in the molten pool.

[0018] The third aspect of the present application provides a control method for an optical system, the optical system comprising an optical unit and a lifting device, the method comprising: controlling a laser beam generated by the optical unit to act on material carried by at least a printing platform to sinter or melt the material, and controlling the laser beam to move along a preset track to build a three-dimensional object layer by layer; and controlling the lifting device to drive the optical unit to move up and down in the z-axis direction to cause the focal point of the laser beam to project on material at different heights. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of the provided drawings.

[0020] Figure 1 is a schematic diagram of an optical system of an embodiment of the present application acting on a printing platform;

[0021] Figure 2 is a structural schematic diagram of an optical unit of an embodiment of the present application;

[0022] Figure 3 is a schematic diagram of different heights of material applied to different levels of an embodiment of the present application;

[0023] Figure 4 is a schematic diagram of different heights of material applied to the same level of an embodiment of the present application;

[0024] Figure 5 is a schematic diagram of an optical system of an embodiment of the present application acting on two printing platforms;

[0025] Figure 6 、 7 、8 are structural schematic diagrams of additive manufacturing equipment of an embodiment of the present application;

[0026] Figure 9 is an assembly schematic diagram of a first printing platform of an embodiment of the present application;

[0027] Figure 10 is a structural and application schematic diagram of a feeding mechanism of an embodiment of the present application;

[0028] Figure 11 is a flow schematic diagram of a control method of an embodiment of the present application. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] According to an embodiment of the present invention, the optical system 10 exhibits the following characteristics: Figures 1-2 The structure shown is optical. The optical system 10 consists of components such as an optical unit 11, a lifting device 12, and a control device 13.

[0031] Optical unit 11 is configured to generate a laser beam 11a, which acts on the material 21a carried by the printing platform 21 to sinter or melt it. During the 3D printing process, optical unit 11 controls the laser beam 11a to move along a preset trajectory to build a three-dimensional object layer by layer. The optical unit 11 mainly consists of components such as laser 111, collimator 112, galvanometer 113, and field lens 114. Among them, laser 111 generates laser beam 11a. After being emitted from laser 111, laser beam 11a enters collimator 112 for collimation to ensure the straight-line propagation of laser beam 11a. Galvanometer 113 is used to control the direction of laser beam 11a. By adjusting its angle, the position of laser beam 11a can be changed, so that it accurately illuminates the printing platform 21. Field lens 114 is used to shape and focus laser beam 11a. It can adjust the cross-sectional shape and focal length of laser beam 11a to meet specific printing requirements. These components work together to precisely guide the laser beam 11a generated by the laser 111 onto the printing platform 21, thereby achieving precise irradiation and scanning of the laser beam 11a.

[0032] The lifting device 12 is configured to control the optical unit 11 to move up and down in the z-axis direction, so that the focal point of the laser beam 11a is projected onto the material 21a at different heights. That is, when the laser beam 11a emitted by the optical unit 11 needs to be projected onto the material 21a at different heights, the lifting device 12 can automatically raise and lower the optical unit 11 as needed to ensure that the focal point is in the accurate position. Different printing requirements may require the focal point to be projected at different heights. For example, after one layer is printed, it may be necessary to move the focal height upward to accommodate the printing requirements of the next layer, or to make precise focal point adjustments on different parts of the material 21a. By controlling the position of the optical unit 11, the lifting device 12 can ensure that the focal point is accurately projected throughout the printing process, thereby ensuring the consistency of print quality.

[0033] The automatic control between the optical unit 11 and the lifting device 12 is achieved by the control device 13, which is an intelligent control system capable of monitoring, analyzing, and responding to printing requirements.

[0034] For example, in actual operation, the control device 13 will first obtain printing requirement information corresponding to the three-dimensional object (model), which may include different levels of printing requirements such as material height distribution, printing path, speed, etc. According to the obtained printing requirement information, the control device 13 will calculate the required focal height position of each layer. After the calculation is completed, the control device 13 will communicate with the optical unit 11 and the lifting device 12, and control the lifting device 12 to automatically adjust the position of the optical unit 11 according to the calculated focal height position, so that the focal point of the optical unit 11 is accurately projected onto the required material height. This process is dynamic, that is, it is optimized and adjusted in real time according to the requirements of different levels during the printing process.

[0035] Through the automatic control of the control device 13, different printing requirements can be efficiently met without manual intervention, thereby improving the production efficiency of additive manufacturing and the consistency of printing quality. The intelligence of the control device 13 enables it to quickly respond to changing requirements, ensuring that the focal height remains accurate throughout the printing process, thereby achieving precise laser focal point control.

[0036] According to an embodiment of the present application, different heights of material 21a are applied at different levels as shown in Figure 3 When the uppermost layer (current layer) of the printing platform 21 is the nth layer, the focal point of the laser beam 11a at a certain scanning position is located at the P1 position, which is close to the top of the nth layer. As the printing progresses, when the nth layer is completed, the printing platform 21 will be driven to descend one layer to carry the new material layer n+1 on the top. At this time, in order to adapt to the nth+1 layer, the focal point position of the laser beam 11a at a certain scanning position needs to be adjusted, that is, the focal height is adjusted by the lifting device 12. According to the instructions of the control device 13, the lifting device 12 automatically adjusts the focal height of the laser beam 11a on the nth+1 layer to move it to the P2 position, which is located near the middle of the nth+1 layer. With the completion of the focal point adjustment, the 3D printing process continues, and the laser beam 11a will form a focal point at the P2 position of the nth+1 layer for printing. This process will be repeated with each layer of printing to ensure that the focal height of the laser beam 11a always matches the required height of the current printing layer (the height at each layer may be the same or different), without the need for manual adjustment, thereby improving the printing quality and production efficiency.

[0037] When the thickness of the nth layer is the same as that of the (n+1th)th layer, the distance between the position of P1 in the nth layer and the position of P2 in the (n+1th)th layer is the distance that the lifting device 12 descends.

[0038] According to an embodiment of the present invention, when materials 21a of different heights are applied to the same layer, such as Figure 4 As shown, when laser beam 11a scans to position q1, control device 13 automatically adjusts the focal position of laser beam 11a along the longitudinal axis of q1, precisely projecting the focal point at P3 below q1. At this time, the position of P3 represents the height position of the focal point in the nth layer. As laser beam 11a continues to scan to the right to position q2, control device 13 again automatically adjusts the focal position of laser beam 11a, precisely projecting the focal point at position P4 along the longitudinal axis of q2. Compared to P3, P4 has a different height position in the nth layer to accommodate position q2 in the nth layer. Thus, this embodiment achieves automatic adjustment of the focal height when materials of different heights are present in the same layer, ensuring accurate projection of the focal point at different positions within the same layer.

[0039] In some embodiments, when the control unit 13 controls the lifting device 12 to lift and lower according to the printing requirements of the three-dimensional object at different levels to automatically adjust the height position of the focus on the material 21a, the printing requirements referred to are, for example, that the upper layer material and the lower layer material are different in at least one of the following factors.

[0040] <Layer Thickness>

[0041] In 3D printing, the focal point of the laser beam determines the area on the material where sintering or melting occurs—the location of the molten pool. If the focal point is too high, the laser beam may sinter above or below the material surface, resulting in poor adhesion or weak bonding between printed layers. Different layers may require sintering or melting at different heights; if the focal height is not adjusted, the focal point may be in the wrong position, causing the shape and structure of the printed layers to not meet printing requirements. Furthermore, different materials may have different melting or sintering temperatures; an incorrect focal point position may waste energy or lead to incomplete sintering.

[0042] <Print path deviation>

[0043] Printing path deviations can cause the laser beam's trajectory to deviate from the original design path. In this case, if the focal height is not fine-tuned, the laser beam may form a spot in the wrong position, resulting in inaccurate printing. This is especially true for more complex structures that typically require very high precision. Path deviations can lead to slight positional differences, which may accumulate between printing layers, resulting in printing effects that do not meet expectations.

[0044] <Material Properties>

[0045] Different materials can have different optical properties, so adjustments need to be made in the focal height to accommodate the properties of the materials.

[0046] <Layer gap>

[0047] In 3D printing, the material of each layer usually needs to be fused or sintered at a specific depth. If the gap between layers changes, the fusion depth will also change accordingly. Adjusting the focal height ensures that the light spot is focused at the required depth of each layer to accommodate different layer gaps. In addition, changes in the gap between layers can also cause changes in temperature and material viscosity, affecting the flowability and fusion behavior of the material. By adjusting the focal height, changes in temperature and viscosity can be accommodated at different levels to ensure proper processing of the material. Furthermore, in cases where the layer gap changes significantly, if the focal height is not adjusted, the optical unit may experience defocusing problems, resulting in the light spot failing to focus at the correct position.

[0048] <Printing speed>

[0049] Changes in printing speed can result in different deposition speeds of materials at different levels. If the deposition speed of the material is faster in a certain layer, the light spot needs to follow the deposition of the material faster to keep the focal point at the required height position. Conversely, if the deposition speed of the material is slower in a certain layer, the focal point needs to be lowered accordingly to accommodate the slow deposition.

[0050] According to an embodiment of the present application, the structure of the optical system 10 is as shown in Figure 5 The laser beam 11a emitted by the optical unit 11 is guided to two different printing platforms, namely the first printing platform 22 and the second printing platform 23, which have different heights in the z-axis, so the focal point of the laser needs to be projected at different height positions.

[0051] The lifting device 12 can lift the optical unit 11 in the z-axis, which adjusts the focal position to accommodate different printing platform heights. Specifically, when printing on the first printing platform 22 is required, the light spot of the laser beam 11a falls at the first position P5, at which the focal point of the laser beam 11a is accurately projected on the material 22a on the first printing platform 22, ensuring that the focal point matches the height of the current printing layer. When printing on the second printing platform 23 is required, the lifting device 12 controls the optical unit 11 to lower so that the light spot falls at the second position P6, at which the focal point of the laser beam 11a is adjusted and accurately projected on the material 23a on the second printing platform 23, ensuring that the focal point matches the height of the second printing platform 23. It should be understood that the first position P5 and the second position P6 have different heights in the z-axis.

[0052] In one example, when the laser beam 11a has completed scanning the last printing position (assumed to be P5) of the first printing platform 22, it needs to move to the first printing position (assumed to be P6) of the second printing platform 23 for scanning. It is assumed that the height difference between the two positions is 10 cm. In this scenario, the lifting device 12 controls the optical unit 11 to lower 10 cm so that the focal point height can adapt to the height of the second printing platform 23, which means that the optical unit 11 lowers from the first position P5 to the second position P6, ensuring that the focal point is above the material 23a of the second printing platform 23. Subsequently, the direction or position in the x-y plane of the laser beam 11a is adjusted accordingly to ensure that the focal point is accurately projected on the first printing position P6 of the second printing platform 23, so that printing can begin at this position.

[0053] It should be understood that the material 22a of the first printing platform 22 and the material 23a on the second printing platform 23 are both suitable for Figure 3 the application of materials of different heights described above is applied to different levels or Figure 4 the application of materials of different heights described above is applied to the same level.

[0054] According to an embodiment of the present application, the structure of the additive manufacturing device 30 is as shown in Figure 6 The additive manufacturing device 30 has a printing cabin 24, in which the first printing platform 22 and the second printing platform 23 are accommodated, and the optical unit 11 is arranged above the cabin top 24a of the printing cabin 24, the laser beam emitted by the optical unit 11 passes through the opening of the cabin top 24a into the printing cabin 24, and the cabin top 24a is controlled by the lifting device 12 to move up and down along the z-axis to gradually approach or move away from the first printing platform 22 and the second printing platform 23, thereby controlling the height of the cabin top 24a by the lifting device 12 to achieve accurate control of the focal point height, so as to adapt to the first printing platform 22 and the second printing platform 23 of different heights.

[0055] The lifting device 12 can be, for example, a hydraulic device, a pneumatic device, a servo motor screw drive device, etc. to provide driving mechanism for reciprocating linear motion.

[0056] For example, in the structure shown in Figure 6 The lifting device 12 is composed of a driving part 12a and four lead screws 12b, which are uniformly arranged in the z-axis direction and penetrate through the cabin top 24a, and the cabin top 24a can be driven by the driving part 12a to move up and down along the lead screws 12b, thereby driving the optical unit 11 above the cabin top 24a to realize accurate lifting motion in the z-axis.

[0057] It should be understood that the additive manufacturing device 30 also has, for example, Figure 7The shown housing 25 is to accommodate the optical unit 11, the lifting portion of the lifting device 12 and the printing cabin 24 inside it.

[0058] In Figures 6-7 In the shown structure, the first printing platform 22 and the second printing platform 23 are installed on the bottom of the printing cabin 24, i.e. the cabin bottom 24b.

[0059] According to an embodiment of the present application, the structure of the additive manufacturing device 30 is as shown in Figure 8 The cabin bottom 24b of the printing cabin 24 is respectively provided with hatch openings 24b-1, 24b-2 and 24b-3, the first printing platform 22 is arranged on the hatch opening 24b-1, and the second printing platform 23 is arranged on the hatch opening 24b-2.

[0060] A feeder 26a is arranged below the hatch opening 24b-1, a forming cylinder 27 is arranged below the hatch opening 24b-2, and a feeder 26b is arranged below the hatch opening 24b-3. A screw motion unit 28a is arranged below the feeder 26a, a screw motion unit 28b is arranged below the forming cylinder 27, and a screw motion unit 28c is arranged below the feeder 26b. When the first printing platform 22 is installed on the hatch opening 24b-1, the feeder 26a below the first printing platform 22 and the screw motion unit 28a are not in operation; after the first printing platform 22 is removed from the hatch opening 24b-1, the hatch opening 24b-1 serves as a material supply port for the second printing platform 23, so that the feeder 26a is driven by the screw motion unit 28a to supply material to the second printing platform 23 from a direction opposite to the feeder 26b (it should be understood that the feeder 26b is driven by the screw motion unit 28c to supply material to the second printing platform 23 from a direction opposite to the feeder 26a), and in this arrangement, when the feeder 26a supplies material to the second printing platform 23, the feeder 26b can collect the excess material on the second printing platform 23 under the action of a scraper (not shown), and similarly, when the feeder 26b supplies material to the second printing platform 23, the feeder 26a can also collect the excess material on the second printing platform 23.

[0061] When printing a part on the second printing platform 23, the screw motion unit 28a drives the material stored in the feeder 26a to move upward to overflow at the hatch opening 24b-1, and a scraper arranged above the cabin bottom 24b is controlled to move in a material laying direction to carry the material overflowing at the hatch opening 24b-1 to the second printing platform 23 above to lay flat, or the screw motion unit 28c drives the material stored in the feeder 26b to move upward to overflow at the hatch opening 24b-3, and the scraper arranged above the cabin bottom 24b is controlled to move in an opposite material laying direction to carry the material overflowing at the hatch opening 24b-3 to the second printing platform 23 above to lay flat.

[0062] Then, the laser beam is emitted by the control optical unit 11 according to a predetermined scanning trajectory to sinter or melt the material laid on the second printing platform 23, thus completing the manufacturing of one layer of material. After that, the second printing platform 23 installed in the forming cylinder 27 is driven to descend by a preset height by the screw motion unit 28b, so as to carry out the material laying and processing of the next layer. The process is repeated until the final forming of the entire three-dimensional object is completed.

[0063] Alternatively, the first printing platform 22 can not be detached from the hatch 24b-1, and only the feeder 26b is used to feed the second printing platform 23.

[0064] Alternatively, the hatch 24b-3 can not be provided on the hatch bottom 24b, and the feeder 26b and the screw motion unit 28c are also cancelled. When the second printing platform 23 needs to be fed, the first printing platform 22 is detached from the hatch 24b-1 to use the feeder 26a to feed the second printing platform 23.

[0065] Reference Figure 5 As shown, in some embodiments, the first printing platform 22 is used as a test printing platform, mainly for experimental or test printing purposes, so as to explore new manufacturing processes, materials or parameter configurations. Specifically, the first printing platform 22 is configured to accept the laying of at least one layer of material 22a, so as to form a molten pool on the surface thereof by scanning of the laser beam 11a emitted by the optical unit 11. While the laser beam 11a acts on the surface of the material 22a, the first printing platform 22 is transmitted through the molten pool by the high-energy X-ray 33 from the x-axis direction to carry out diffraction imaging, so as to obtain in-situ characterization information of the internal organizational phase of the molten pool, thereby providing real-time material microstructure information for the experimental printing process, facilitating the understanding of the printing effect under different conditions, and further optimizing the manufacturing process.

[0066] In order to ensure that the high-energy X-ray 33 effectively penetrates the molten pool and transmits through the first printing platform 22, the first printing platform 22 in some embodiments is set to be close to two-dimensional features, i.e., the width in the x-axis direction is narrow, so as to minimize the absorption and scattering of the high-energy X-ray 33, so that the high-energy X-ray 33 maintains sufficient intensity when penetrating the material 22a to carry out transmission and further diffraction imaging.

[0067] For example, the width of the first printing platform 22 is set to be at least the width of the molten pool, and at most 2 mm.

[0068] Setting the minimum width of the first printing platform 22 to be the width of the melt pool ensures that the platform can completely cover the melt pool, enabling the platform to allow the laser beam 11a to complete the scan formation over it and enabling the high-energy X-rays 33 to be transmitted through the entire melt pool, thereby obtaining complete information of the internal tissue phase of the melt pool. Although designs close to two-dimensional features help to reduce absorption and scattering, the platform still needs to have sufficient width to maintain the stability of the structure to support the building process of the melt pool, and a preferred embodiment based on this is to limit the maximum width of the first printing platform 22 to 2mm.

[0069] Figure 9 An assembled embodiment of the first printing platform 22 is shown. In this embodiment, the outer side of the first printing platform 22 is provided with a shielding part 29a-29d capable of limiting the material within the scanning area to avoid the material overflowing from the scanning area. It should be understood that the scanning area refers to the area on which the laser beam acts on the material carried by the first printing platform 22, which can be equal to the area covered by the surface of the first printing platform 22, or in other cases, it can be smaller than the area covered by the surface of the first printing platform 22, but it cannot be smaller than the area covered by a melt pool in the extreme case.

[0070] For example, when the scanning area is smaller than the length of the first printing platform 22 in the length (y-axis) direction, only the shielding parts 29a and 29b can be provided outside the scanning area, and 29c and 29d in the width (x-axis) direction are not provided. It should be understood that the shielding parts 29a-29d are at least higher than the scanning area by the height of a melt pool or the height of a layer of material, with the scanning area as the reference surface.

[0071] In order to ensure the smooth transmission of high-energy X-rays in the scanning area, the part of the shielding parts 29a-29d that is higher than the scanning area is made of transparent material.

[0072] In an example, the bottom part (the part lower than the scanning area) of the shielding parts 29a-29d is made of non-transparent, high-density material, such as metal or ceramic; and the top part (the part higher than the scanning area) of the shielding parts 29a-29d is made of transparent material, which is usually a material that is easy for high-energy X-rays to transmit and has high-temperature resistance, such as glass carbon, alumina ceramic glass, high borosilicate glass, etc.

[0073] In another example, the entire shielding parts 29a-29d are made of transparent material.

[0074] According to an embodiment of the present application, a pressing plate 31 is arranged outside the shielding part 29a-29d, which mainly serves to provide additional stable support and ensure that the shielding part 29a-29d remains fixed during the 3D printing process. By introducing the arrangement of the pressing plate 31, the influence of factors such as equipment vibration and material movement on the shielding part 29a-29d can be effectively reduced, which helps to ensure that the first printing platform 22 always remains in the correct position during the 3D printing process, and in turn ensures the smooth transmission of high-energy X-rays for in-situ monitoring and diffraction imaging.

[0075] According to an embodiment of the present application, an air inlet and outlet field 32 is arranged on one side of the first printing platform 22. During the sintering or melting process of the material, smoke particles will be generated and accumulated near the first printing platform 22. The arrangement of the air inlet and outlet field 32 can blow away these accumulated smoke particles, keeping the working environment clean. In addition, the accumulated smoke particles may interfere with the penetration of high-energy X-rays, reducing their efficiency. By arranging the air inlet and outlet field 32, these interference factors can be effectively excluded, ensuring that high-energy X-rays can penetrate smoothly to perform accurate monitoring and imaging. In a specific structural arrangement, the air inlet and outlet field 32 can be arranged above the pressing plate 31 on the side of the shielding part 29b. The air inlet and outlet field 32 is provided with a plurality of air inlet holes on the side facing the first printing platform 22 to generate a uniform air flow field, thereby removing the smoke particles accumulated near the first printing platform 22.

[0076] According to an embodiment of the present application, in order to cooperate with the work of high-energy X-rays, the additive manufacturing equipment of the present application also has a high-energy X-ray device for emitting high-energy X-rays to transmit the molten pool diffraction imaging to obtain the in-situ characterization of the organization phase in the molten pool.

[0077] According to an embodiment of the present application, the structure of the feeding mechanism is as shown in Figure 10 The feeding mechanism is arranged in the height direction of the first printing platform 22 and is composed of a material spreading part 124, a material storage part 126, and a feeding part 125. The feeding part 125 penetrates into the material storage part 126 along the z-axis direction and carries at least part of the material in the material storage part 126 to move downward through the gap between the material storage part 126 and the feeding part 125 in a rotating state, so that it falls on the first printing platform 22. The material spreading part 124 is used to move and uniformly spread the material on the first printing platform 22.

[0078] The storage portion 126 has an opening for receiving the material. The opening can be configured in a fully open state to allow the material to freely enter, in a semi-open state to allow the material to enter under certain restrictions, or in some cases, the opening can be configured to only have a through hole for the material to smoothly enter. Correspondingly, a sealable cover can be provided on the opening to prevent the material from overflowing from the storage portion 126 during high-speed operation.

[0079] The feeding portion 125 is configured to penetrate the storage portion 126 along the z-axis direction, preferably coinciding with the longitudinal axis of the storage portion 126. The feeding portion 125 during the feeding process is controlled to be in a rotating state, and under the action of the rotating state, carries at least part of the material in the storage portion 126 to the gap between the storage portion 126 and the feeding portion 125, and moves downward with the rotation of the feeding portion 125. In this process, the material eventually separates from the gap and gradually falls on the first printing platform 22. The gap has a certain geometric shape and size to at least ensure that the minimum physical constituent unit of the material (e.g. the particles of the material) can freely flow in the gap.

[0080] The material spreading portion 124 is used to move the material on the first printing platform 22 to uniformly spread the material scattered on the first printing platform 22, thereby forming a material layer for further manufacturing.

[0081] In some embodiments, the feeding portion 125 is configured by a screw rod 125a and a rotating driving device 125b for driving the screw rod 125a to rotate. One end of the screw rod 125a is connected with the rotating driving device 125b, and the other end extends downward from the storage portion 126 by a distance, and the extended section of the screw rod 125a plays a role of conveying and pushing the material. When the rotating driving device 125b is activated, it can drive the screw rod 125a to rotate, so that the screw rod 125a drives the material stored in the storage portion 126 to move downward in a rotating state.

[0082] In some embodiments, the storage portion 126 is configured by a hopper 126a and a leakage cylinder 126b. The hopper 126a and the leakage cylinder 126b are designed to be integrally formed or tightly connected together by other connection methods to form an integral storage portion 126.

[0083] In the material storage section 126, the material is stored in the hopper 126a, and the material leakage cylinder 126b extends downward from the bottom of the hopper 126a by at least a distance to wrap the screw 125a of the material feeding section 125 extending downward from the bottom of the hopper 126a, that is, the height of the material leakage cylinder 126b is at least equal to the height of the screw 125a below the hopper 126a, so as to control the delivery of the material. The design of the material leakage cylinder 126b helps to guide and direct the material carried by the screw 125a, and the material can be controlled through the gap between the material leakage cylinder 126b and the material feeding section 125 to ensure that it moves downward along a specific path.

[0084] In some embodiments, the material spreading section 124 is arranged separately from the material feeding section 125, and the material spreading section 124 is driven to move on the first printing platform 22 by a separate power source.

[0085] In some embodiments, the material spreading section 124 is arranged integrally with the material feeding section 125, for example, connected together by a mounting seat. In this configuration, the material feeding section 125 is responsible for delivering and supplying the material to the first printing platform 22, and the material spreading section 124 is responsible for uniformly spreading the material on the first printing platform 22, and the material spreading section 124 is arranged at intervals near the material feeding section 125.

[0086] For example, the material spreading section 124 is arranged to be composed of two scrapers, scraper 124a and scraper 124b, which are respectively located on the left and right sides of the material feeding section 125, for example, the scraper 124a is located on the left side of the material feeding section 125, and the scraper 124b is located on the right side of the material feeding section 125.

[0087] In some embodiments, the bottom of the material leakage cylinder 126b is used as the material spreading section 124 to complete the feeding and spreading tasks in one operation. It should be understood that the bottom of the material leakage cylinder 126b has a material release opening and a certain size of edge portion, that is, the bottom of the material leakage cylinder 126b not only serves as a material release opening, but also has a certain size of edge portion, which can be used to control and distribute the material on the first printing platform 22.

[0088] According to an embodiment of the present application, a control method 40 is provided, which presents a flow as shown in Figure 11 The control method 40 is used to control the optical system 10 described above, and the execution steps of the control method 40 are composed of S41 and S42.

[0089] S41: controlling the laser beam generated by the optical unit to act on the material carried by at least one printing platform to sinter or melt the material, and controlling the laser beam to move along a predetermined trajectory to build a three-dimensional object layer by layer;

[0090] S42: controlling the lifting device to drive the optical unit to move up and down in the z-axis direction, so as to make the focal point of the laser beam project on the material at different heights.

[0091] In some embodiments, the materials are the same layer, or different layers.

[0092] In some embodiments, the control method 40 further comprises: controlling the lifting device to move up and down according to the printing requirements of the three-dimensional object at different layers, so as to automatically adjust the height position of the focal point on the material.

[0093] In some embodiments, the printing requirements include at least one of the following factors: layer thickness, printing path deviation, material characteristics, layer gap, printing speed, which are different between the last layer of material and the next layer of material.

[0094] The specific implementation process of the control method 40 is consistent with the operation process of the optical system 10 described above, and will not be repeated here.

[0095] In the description of the present specification, the description of the terms "an embodiment", "some embodiments", "an example", "a specific example", or "exemplary" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0096] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

[0097] List of reference signs

[0098] 10 optical system

[0099] 11 optical unit

[0100] 111 laser

[0101] 112 collimator

[0102] 113 galvanometer

[0103] 114 field lens

[0104] 12 lifting device

[0105] 12a drive section

[0106] 12b lead screw

[0107] 13 control device

[0108] 21 printing platform

[0109] 22 first printing platform

[0110] 23 second printing platform

[0111] 21a, 22a, 23a material

[0112] 24 printing cabin

[0113] 24a cabin top

[0114] 24b cabin bottom

[0115] 24b-1, 24b-2, 24b-3 hatch

[0116] 25 shell

[0117] 26a, 26b feeder

[0118] 27 forming cylinder

[0119] 28a, 28b, 28c lead screw movement unit

[0120] 29a, 29b, 29c, 29d shielding section

[0121] 30 additive manufacturing device

[0122] 31 pressure disc

[0123] 32 air inlet and outlet field

[0124] 33 high-energy X-ray

[0125] 124 material spreading section

[0126] 124a, 124b scraper

[0127] 125 material feeding section

[0128] 125a screw

[0129] 125b rotary drive device

[0130] 126 material storage section

[0131] 126a hopper

[0132] 126b material leakage cylinder

[0133] 40 Control method.

Claims

1. An optical system for additive manufacturing, characterized in that, include: An optical unit is configured to generate a laser beam that acts on a material carried by at least one printing platform to sinter or melt it, and to control the laser beam to move along a preset trajectory to build a three-dimensional object layer by layer. There are two printing platforms, namely a first printing platform and a second printing platform having different heights on the z-axis. The material carried on the first printing platform is scanned by the laser beam to form a molten pool, and during the scanning process, it is diffracted by high-energy X-rays transmitted through the molten pool to obtain in-situ characterization of the tissue phase within the molten pool. The material carried by the second printing platform is scanned layer by layer by the laser beam to construct the three-dimensional object; The lifting device is configured to control the optical unit to move up and down in the z-axis direction so as to cause the focal point of the laser beam to be projected onto materials at different heights, wherein the materials at different heights are the same layer or different layers; The control unit is used to control the lifting device to move up and down according to the printing requirements of the three-dimensional object at different levels, so as to automatically adjust the height position of the focus on the material. The printing requirements include that the upper layer material and the lower layer material are different in at least one of the following factors: layer thickness, printing path deviation, material properties, layer gap, and printing speed.

2. The optical system according to claim 1, characterized in that, The lifting device is further configured to lift the optical unit along the z-axis, so that the focal point is projected onto the material of the first printing platform at a first position and onto the material of the second printing platform at a second position, wherein the first position and the second position have different heights along the z-axis.

3. The optical system according to claim 1, characterized in that, The at least one printing platform is disposed inside a printing chamber, the optical unit is disposed on the top of the printing chamber, and the laser beam emitted by the optical unit enters the printing chamber through the opening in the top of the chamber.

4. The optical system according to claim 3, characterized in that, The top of the cabin moves up and down along the z-axis under the control of the lifting device to gradually move closer to or away from the printing platform.

5. The optical system according to claim 1, characterized in that, The width of the first printing platform is at least the width of the molten pool and at most 2 mm.

6. An additive manufacturing apparatus, characterized in that, include: At least one printing platform is required to support the material; as well as The optical system according to any one of claims 1-5.

7. The additive manufacturing equipment according to claim 6, characterized in that, Also includes: A high-energy X-ray device is used to emit high-energy X-rays for transmission molten pool diffraction imaging to obtain in-situ characterization of the tissue phases within the molten pool.

8. A control method for the optical system according to any one of claims 1-5, characterized in that, The method includes: The laser beam generated by the optical unit is controlled to act on the material carried by at least one printing platform to sinter or melt it, and the laser beam is controlled to move along a preset trajectory to build a three-dimensional object layer by layer; The lifting device is controlled to move the optical unit up and down in the z-axis direction, so that the focal point of the laser beam is projected onto the material at different heights.

9. The control method according to claim 8, characterized in that, The materials may be of the same or different layers.

10. The control method according to claim 9, characterized in that, The method further includes: The lifting device is controlled to rise and fall according to the printing requirements of the three-dimensional object at different levels, so as to automatically adjust the height position of the focus on the material.

11. The control method according to claim 10, characterized in that, The printing requirements include differences between the upper and lower layer materials in at least one of the following factors: Layer thickness, print path deviation, material properties, interlayer gap, and printing speed.

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