Ultra-precision additive and subtractive material area printing method and printing device

Abstract

The invention discloses an ultra-precise additive and subtractive material area printing method and device, and the method comprises the steps: laying powder according to the information of a printing layer in the printing process of each printing layer; carrying out regional printing on the powder by utilizing a multi-flat-topped light beam; obtaining a three-dimensional outline of the printing layer; generating a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer; performing defect detection on the printing layer three-dimensional contour model to obtain a defect detection result; wherein the defect detection result comprises convex defect information and concave defect information; according to a defect detection result, carrying out defect material reduction treatment on the printing layer; the height of the printing layer is kept unchanged, and in-situ secondary powder laying is carried out; and after secondary powder laying is finished, secondary additive manufacturing is conducted on the sunken defects subjected to material reduction treatment in the printing layer through picosecond laser. The defects can be detected, removed and repaired, it is guaranteed that the surface of the printing layer is flat, and the printing quality of the printing layer is improved.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing technology, and in particular to an ultra-precision additive and subtractive area printing method and a printing device. Background Art

[0002] Additive manufacturing technology, also known as 3D printing technology, is a technology that manufactures three-dimensional objects by stacking materials layer by layer. Unlike traditional casting technology, additive manufacturing directly manufactures objects based on digital model files, and can produce complex structures without molds. This technology is widely used in aerospace, automotive, medical, electronics, construction and other fields, with the advantages of saving materials, shortening production cycles, reducing manufacturing costs, and enabling personalized customization. Due to its unique manufacturing method, additive manufacturing can produce complex geometric shapes that cannot be achieved by traditional manufacturing methods, greatly expanding the boundaries of product design.

[0003] However, additive manufacturing technology still faces some challenges and defects in practical applications. First, although additive manufacturing can use a variety of materials, some materials may shrink, deform, and other problems during the printing process, resulting in microcracks and pores inside the finished product, thus affecting its precision and mechanical properties. Especially in the manufacture of high-performance components, the microstructure and mechanical properties of the material are crucial to the final product, and these defects may lead to reduced fatigue strength and service life of the components. Secondly, in the additive manufacturing process, due to the characteristics of layer-by-layer stacking, the printed surface is often rough, and there may be structural unevenness between different layers. This layer-by-layer manufacturing method may result in poor surface quality of the product, and even obvious surface defects in applications with high precision requirements, affecting the appearance and functionality of the product, especially in the manufacture of some precision equipment and medical devices. This problem is particularly prominent.

[0004] In addition, although additive manufacturing can show advantages in design flexibility and small-batch production, its printing speed is relatively slow, especially in large-scale production, additive manufacturing technology is still difficult to compare with traditional manufacturing methods. For example, in the large-scale production of parts in the automotive and aerospace industries, traditional casting and processing technologies can achieve higher production efficiency, while the layer-by-layer construction method of additive manufacturing still has certain bottlenecks in production efficiency. Summary of the invention

[0005] In order to solve the technical problems existing in the background technology, the present invention proposes an ultra-precision additive and subtractive material area printing method and printing device.

[0006] The present invention provides an ultra-precision additive and subtractive material area printing method, comprising:

[0007] Establish a three-dimensional model of the part to be molded;

[0008] The three-dimensional model is sliced ​​layer by layer to obtain multiple printing layers;

[0009] Print layer by layer according to the multi-layer printing layer;

[0010] Wherein, during the printing process of each printing layer, the powder is laid according to the information of the printing layer;

[0011] When the powder is laid, the powder is regionally printed using multiple flat-top beams;

[0012] When the area is printed, the three-dimensional contour of the printed layer is obtained;

[0013] Generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer;

[0014] Performing defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information;

[0015] According to the defect detection result, the printed layer is subjected to defect reduction processing;

[0016] The height of the printed layer is kept unchanged, and secondary powder spreading is performed in situ to fill powder into the concave defects in the printed layer that have undergone defect reduction processing;

[0017] After the second powder laying is completed, a picosecond laser is used to perform secondary additive manufacturing on the concave defects in the printed layer that have been processed by subtractive processing.

[0018] Preferably, after performing secondary additive manufacturing on the concave defects in the printed layer that have been subjected to subtractive processing by using a picosecond laser, the method further comprises:

[0019] The printed layer is remelted in situ using a high-repetition-rate picosecond laser.

[0020] Preferably, the parameters for in-situ remelting using a high repetition rate picosecond laser include: a frequency of 3-5 MHz, a laser power of 3-10 W, a scanning speed of 20-100 mm / s, and a spot diameter of 15-35 μm.

[0021] Preferably, obtaining the three-dimensional profile of the printed layer specifically includes:

[0022] A laser three-dimensional imager is used to obtain the three-dimensional profile of the printed layer.

[0023] Preferably, defect detection is performed on the three-dimensional contour model of the printed layer to obtain defect detection results, specifically including:

[0024] Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers;

[0025] Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers;

[0026] According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained.

[0027] According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

[0028] Preferably, determining a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer with a convex defect, and a three-dimensional contour slice layer with a concave defect from a plurality of three-dimensional contour slice layers specifically includes:

[0029] respectively obtaining the solidity ratios of a plurality of three-dimensional contour slice layers;

[0030] From top to bottom, the first three-dimensional contour slice layer with a solidity greater than 99% is defined as the reference layer;

[0031] Determine a three-dimensional contour slice layer with a solidity rate less than 99% as a three-dimensional contour slice layer with a convex defect;

[0032] The remaining three-dimensional contour slice layers with a solidity ratio greater than 99% are determined as three-dimensional contour slice layers with concave defects;

[0033] Among them, the protrusion defects include spheroidization, humps and unmelted particles, and the concave defects include microcracks, pores and bubbles.

[0034] Preferably, according to the defect detection result, the printed layer is subjected to defect reduction processing, specifically comprising:

[0035] Using a picosecond laser to perform subtractive processing on the convex defects of the printing layer according to the convex defect information;

[0036] Picosecond laser is used to perform subtractive processing on the depression defects of the printing layer according to the defect depression information.

[0037] In a second aspect, the present invention further proposes an ultra-precision additive and subtractive material area printing device, comprising: a three-dimensional scanning mechanism, a picosecond laser output mechanism, a multi-flat-top laser output mechanism, a molding mechanism, a defect detection mechanism and a control mechanism; the three-dimensional scanning mechanism, the picosecond laser output mechanism, the multi-flat-top laser output mechanism, the molding mechanism, and the defect detection mechanism are electrically connected to the control mechanism respectively, and the control mechanism is used to control the three-dimensional scanning mechanism, the picosecond laser output mechanism, the multiple flat-top laser output mechanisms, the molding mechanism, and the defect detection mechanism to coordinate actions to achieve layer-by-layer printing of multiple printing layers;

[0038] Wherein, during the printing process of each printing layer, the control mechanism is used to control the scraper of the molding mechanism to spread powder on the molding substrate of the molding mechanism;

[0039] When the powder spreading is completed, the control mechanism is used to control the multi-flat-top laser output mechanism to perform regional printing;

[0040] When the area printing is completed, the control mechanism is used to control the three-dimensional scanning mechanism to obtain the three-dimensional contour of the printing layer;

[0041] The control mechanism is also used to generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer;

[0042] The control mechanism is also used to control the defect detection mechanism to perform defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information;

[0043] The control mechanism is also used to control the picosecond laser output mechanism to output the picosecond laser to perform defect reduction processing on the printed layer according to the defect detection result;

[0044] When the defect reduction processing is completed, the control mechanism is also used to control the height of the molding substrate of the molding mechanism to remain stationary, so as to keep the height of the printing layer stationary, and at the same time control the scraper to perform secondary powder spreading in situ, so as to fill powder into the concave defects in the printing layer that have undergone the defect reduction processing;

[0045] When the secondary powder spreading is completed, the control mechanism is also used to control the picosecond laser output mechanism to perform secondary additive manufacturing on the concave defects in the printing layer that have been subjected to subtractive processing.

[0046] Preferably, the control mechanism is also used to control the picosecond laser output mechanism to output a high-repetition-rate picosecond laser to in-situ remelt the printed layer after controlling the picosecond laser output mechanism to perform secondary additive manufacturing on the recessed defects in the printed layer that have been subjected to subtractive processing.

[0047] Preferably, the process in which the control mechanism controls the defect detection mechanism to perform defect detection specifically includes:

[0048] Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers;

[0049] Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers;

[0050] According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained.

[0051] According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

[0052] Preferably, determining a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer with a convex defect, and a three-dimensional contour slice layer with a concave defect from a plurality of three-dimensional contour slice layers specifically includes:

[0053] respectively obtain the solidity ratios of multiple three-dimensional contour slice layers;

[0054] From top to bottom, the first three-dimensional contour slice layer with a solidity greater than 99% is defined as the reference layer;

[0055] Determine a three-dimensional contour slice layer with a solidity rate less than 99% as a three-dimensional contour slice layer with a convex defect;

[0056] The remaining three-dimensional contour slice layers with a solidity ratio greater than 99% are determined as three-dimensional contour slice layers with concave defects;

[0057] Among them, the protrusion defects include spheroidization, humps and unmelted particles, and the concave defects include microcracks, pores and bubbles.

[0058] In the printing process of each printing layer of the present invention, a scraper is first used to spread powder on a forming substrate; when the powder spreading is completed, a multi-flat-top beam is used to perform regional printing; when the regional printing is completed, a three-dimensional contour of the printing layer is obtained; according to the three-dimensional contour of the printing layer, a three-dimensional contour model of the printing layer is generated; defect detection is performed on the three-dimensional contour model of the printing layer to obtain a defect detection result; wherein the defect detection result includes convex defect information and concave defect information; according to the defect detection result, the printing layer is subjected to defect subtractive processing; when the defect subtractive processing is completed, the height of the printing layer is kept unchanged, and secondary powder spreading is performed in situ to fill powder into the concave defect in the printing layer that has undergone defect subtractive processing; when the secondary powder spreading is completed, a picosecond laser is used to perform secondary additive manufacturing on the concave defect in the printing layer that has undergone subtractive processing.

[0059] In the present invention, the proposed ultra-precision additive and subtractive area printing method and printing device can detect defects on each printed layer after it is printed, and perform defect subtractive processing based on the defect detection results. After the defect subtractive processing is completed, secondary powder laying is performed in situ and secondary additive manufacturing is performed on the concave defects in the printed layer that have been subtractively processed using a picosecond laser to repair the concave defects, ensure the surface smoothness of the printed layer, and improve the printing quality of the printed layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 Schematic diagram of the process of an ultra-precision additive and subtractive material area printing method in one embodiment of the present invention.

[0061] Figure 2A schematic diagram of the mechanism of an ultra-precision additive and subtractive material area printing method in one embodiment of the present invention.

[0062] Figure 3 A schematic diagram of a slice of a three-dimensional contour model of a printing layer in an embodiment of the present invention.

[0063] Figure 4 It is a schematic top view of a plurality of three-dimensional contour slice layers arranged from top to bottom in one embodiment of the present invention.

[0064] Figure 5 It is a schematic structural diagram of an ultra-precision additive and subtractive material area printing device in one embodiment of the present invention. DETAILED DESCRIPTION

[0065] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0066] First, as Figure 1 As shown, the present invention proposes an ultra-precision additive and subtractive material area printing method, comprising:

[0067] Establish a three-dimensional model of the part to be molded;

[0068] The three-dimensional model is sliced ​​layer by layer to obtain multiple printing layers;

[0069] Print layer by layer according to the multi-layer printing layer;

[0070] Wherein, during the printing process of each printing layer, the powder is laid according to the information of the printing layer;

[0071] When the powder is laid, the powder is regionally printed using multiple flat-top beams;

[0072] When the area is printed, the three-dimensional contour of the printed layer is obtained;

[0073] Generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer;

[0074] Performing defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information;

[0075] According to the defect detection result, the printed layer is subjected to defect reduction processing;

[0076] The height of the printed layer is kept unchanged, and secondary powder spreading is performed in situ to fill powder into the concave defects in the printed layer that have undergone defect reduction processing;

[0077] After the second powder laying is completed, a picosecond laser is used to perform secondary additive manufacturing on the concave defects in the printed layer that have been processed by subtractive processing.

[0078] In the printing process of each printing layer of the present invention, a scraper is first used to spread powder on a forming substrate; when the powder spreading is completed, a multi-flat-top beam is used to perform regional printing; when the regional printing is completed, a three-dimensional contour of the printing layer is obtained; according to the three-dimensional contour of the printing layer, a three-dimensional contour model of the printing layer is generated; defect detection is performed on the three-dimensional contour model of the printing layer to obtain a defect detection result; wherein the defect detection result includes convex defect information and concave defect information; according to the defect detection result, the printing layer is subjected to defect subtractive processing; when the defect subtractive processing is completed, the height of the printing layer is kept unchanged, and secondary powder spreading is performed in situ to fill powder into the concave defect in the printing layer that has undergone defect subtractive processing; when the secondary powder spreading is completed, a picosecond laser is used to perform secondary additive manufacturing on the concave defect in the printing layer that has undergone subtractive processing.

[0079] The present invention can first perform defect detection on each printing layer after printing is completed, and perform defect subtractive processing according to the defect detection result, and after the defect subtractive processing is completed, perform in-situ secondary powder spreading and use a picosecond laser to perform secondary additive manufacturing on the concave defects in the printing layer that have been subjected to subtractive processing, so as to repair the concave defects, ensure the surface flatness of the printing layer, and improve the printing quality of the printing layer.

[0080] Moreover, the traditional laser light source is a Gaussian light source with a spot diameter of 80-100μm. The nature of the Gaussian distribution determines that the temperature gradient generated during the material processing is large, which may cause defects such as spheroidization, humps, unmelted, microcracks and pores in the printed layer;

[0081] This embodiment uses multiple flat-top beams for regional printing. The flat-top beam spot diameter is 240-300 μm. The energy is evenly distributed in the center and quickly drops to zero at the edge, which plays a decisive role in reducing defects and improving printing efficiency.

[0082] It should be noted that the “multi-flat-top beam” in this embodiment includes two or more flat-top beams, and the beam of the picosecond laser is one or more.

[0083] Specifically, the parameters of picosecond laser for secondary additive manufacturing include: frequency of 1-20 MHz, laser power of 5-10 W, scanning speed of 40-100 mm / s, and spot diameter of 15-35 μm.

[0084] However, the surface of the printed layer that has undergone defect subtractive processing has a relatively high surface roughness, and the repaired area and the unrepaired area of ​​the printed layer are not completely combined, resulting in stress concentration, which may cause local deformation in subsequent processing. In order to solve this problem, in this embodiment, after using a picosecond laser to perform secondary additive manufacturing on the concave defect in the printed layer that has undergone subtractive processing, it also includes:

[0085] The printed layer is remelted in situ using a high-repetition-rate picosecond laser.

[0086] After the defect reduction treatment is completed in this embodiment, the printed layer is remelted in situ using a high repetition rate picosecond laser to form a remelted layer. The formation of the remelted layer can effectively improve the surface quality of the printed layer and reduce the roughness, and more effectively improve the uniformity of the interlayer bonding and the overall performance of the material. The mechanism diagram of this embodiment is shown in FIG. Figure 2 shown.

[0087] Specifically, the parameters for in-situ remelting using a high repetition rate picosecond laser include: a frequency of 3-5 MHz, a laser power of 3-10 W, a scanning speed of 20-100 mm / s, and a spot diameter of 15-35 μm.

[0088] In this embodiment, obtaining the three-dimensional profile of the printed layer specifically includes:

[0089] A laser three-dimensional imager is used to obtain the three-dimensional profile of the printed layer.

[0090] The laser three-dimensional imager in this embodiment is a device based on laser scanning technology, which can capture the surface shape and structure of an object with high precision to create its three-dimensional model.

[0091] In order to obtain accurate defect detection results, such as Figure 3 and Figure 4 As shown, in this embodiment, defect detection is performed on the three-dimensional contour model of the printed layer to obtain defect detection results, which specifically include:

[0092] Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers;

[0093] Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers;

[0094] According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained.

[0095] According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

[0096] Since the 3D contour usually exists in the form of a mesh model (such as a triangular mesh) or point cloud data. The contour slicing process is to layer the 3D mesh model along the preset slicing direction (construction direction, usually the Z axis) to generate multiple 2D 3D contour slice layer images, which will show the cross-sectional view of the printed layer. Therefore, the reference layer can be determined based on the cross-sectional view of the printed layer.

[0097] It should be understood that this embodiment uses software such as Cura, PrusaSlicer, and Slimplify3D to perform contour slicing on the three-dimensional contour model of the printing layer.

[0098] In the process of determining the reference layer, the solidity ratio is used as the criterion. The calculation formula of the solidity ratio is:

[0099] In the formula, is the solidity rate, S 实心 is the area of ​​the solid part of the 3D contour slice layer, S 总 is the total area of ​​the 3D contour slice layer.

[0100] Specifically, the solid rates of multiple three-dimensional contour slicing layers are determined from top to bottom, and the first three-dimensional contour slicing layer with a solid rate greater than 99% is defined as a reference layer; the three-dimensional contour slicing layer with a solid rate less than 99% is regarded as a three-dimensional contour slicing layer with a convex defect, which needs to be subsequently reduced in order to eliminate the convex defect; the remaining three-dimensional contour slicing layers with a solid rate greater than 99% are regarded as three-dimensional contour slicing layers with a concave defect, which need to be subjected to cavity reduction (digging pits).

[0101] Among them, raised defects include spheroidization, humps, and unmelted particles, and recessed defects include microcracks, pores, and bubbles.

[0102] In a further embodiment, according to the defect detection result, the printed layer is subjected to defect reduction processing, specifically comprising:

[0103] Using a picosecond laser to perform subtractive processing on the convex defects of the printing layer according to the convex defect information;

[0104] Picosecond laser is used to perform subtractive processing on the depression defects of the printing layer according to the defect depression information.

[0105] This embodiment can first use a picosecond laser to perform subtractive processing on the raised defects of the printed layer according to the raised defect information, and perform subtractive processing on the sunken defects of the printed layer according to the defect sunken information, thereby effectively avoiding the influence of the raised defects on the subsequent in-situ secondary powdering of the pits produced by the sunken defects.

[0106] Specifically, the parameters for picosecond laser subtractive processing include: frequency of 100KHz, laser power of 5-15W, scanning speed of 100-500mm / s, and spot diameter of 15-35μm.

[0107] Second, as Figure 5 As shown, the present invention also proposes an ultra-precision additive and subtractive material area printing device, including: a three-dimensional scanning mechanism 5, a picosecond laser output mechanism 4, a multi-flat-top laser output mechanism 3, a molding mechanism, a defect detection mechanism and a control mechanism;

[0108] The three-dimensional scanning mechanism 5, the picosecond laser output mechanism 4, the multi-flat-top laser output mechanism 3, the molding mechanism, and the defect detection mechanism are electrically connected to the control mechanism respectively, and the control mechanism is used to control the three-dimensional scanning mechanism 5, the picosecond laser output mechanism 4, the multiple flat-top laser output mechanisms, the molding mechanism, and the defect detection mechanism to coordinate actions to realize layer-by-layer printing of multiple printing layers;

[0109] Wherein, during the printing process of each printing layer, the control mechanism is used to control the scraper 2 of the molding mechanism to spread powder on the molding substrate 1 of the molding mechanism;

[0110] When the powder spreading is completed, the control mechanism is used to control the multi-flat-top laser output mechanism 3 to perform regional printing;

[0111] When the area printing is completed, the control mechanism is used to control the three-dimensional scanning mechanism 5 to obtain the three-dimensional contour of the printed layer;

[0112] The control mechanism is also used to generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer;

[0113] The control mechanism is also used to control the defect detection mechanism to perform defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information;

[0114] The control mechanism is also used to control the picosecond laser output mechanism 4 to output the picosecond laser to perform defect reduction processing on the printed layer according to the defect detection result;

[0115] When the defect reduction processing is completed, the control mechanism is also used to control the height of the molding substrate 1 of the molding mechanism to remain stationary, so as to keep the height of the printed layer stationary, and at the same time control the scraper 2 to perform secondary powder spreading in situ, so as to fill powder into the concave defects in the printed layer that have undergone the defect reduction processing;

[0116] After the secondary powder spreading is completed, the control mechanism is also used to control the picosecond laser output mechanism 4 to perform secondary additive manufacturing on the concave defects in the printing layer that have been subjected to subtractive processing.

[0117] In this embodiment, the control mechanism is also used to control the picosecond laser output mechanism 4 to output a high-repetition-rate picosecond laser to in-situ remelt the printed layer after controlling the picosecond laser output mechanism 4 to perform secondary additive manufacturing on the recessed defects in the printed layer that have undergone subtractive processing.

[0118] Specifically, the parameters for in-situ remelting using a high repetition rate picosecond laser include: a frequency of 3-5 MHz, a laser power of 3-10 W, a scanning speed of 20-100 mm / s, and a spot diameter of 15-35 μm.

[0119] The three-dimensional scanning mechanism 5 in this embodiment is specifically a laser three-dimensional imager, which can accurately and quickly obtain the three-dimensional contour data of the printing layer, facilitating subsequent rapid modeling.

[0120] The process of defect detection by the defect detection mechanism in this embodiment specifically includes:

[0121] Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers;

[0122] Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers;

[0123] According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained.

[0124] According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

[0125] The defect detection mechanism in this embodiment uses software such as Cura, PrusaSlicer, Slimplify3D, etc. to perform contour slicing on the three-dimensional contour model of the printing layer.

[0126] Specifically, this embodiment uses the solidity ratio as a criterion to determine the reference layer. The calculation formula of the solidity ratio is: In the formula, is the solidity rate, S 实心 is the area of ​​the solid part of the 3D contour slice layer, S 总 is the total area of ​​the 3D contour slice layer.

[0127] First, the solidity rates of multiple three-dimensional contour slice layers are obtained; then, from top to bottom, the first three-dimensional contour slice layer with a solidity rate greater than 99% is defined as the reference layer; the three-dimensional contour slice layer with a solidity rate less than 99% is regarded as a three-dimensional contour slice layer with a convex defect, which needs to be subsequently reduced in order to eliminate the convex defect; the remaining three-dimensional contour slice layers with a solidity rate greater than 99% are regarded as three-dimensional contour slice layers with a concave defect, which need to be subjected to cavity reduction (digging pits).

[0128] Among them, raised defects include spheroidization, humps, and unmelted particles, and recessed defects include microcracks, pores, and bubbles.

[0129] In this embodiment, during the defect subtractive processing, the picosecond laser output mechanism 4 first uses the picosecond laser to perform subtractive processing on the raised defects of the printed layer according to the raised defect information, and then uses the picosecond laser to perform subtractive processing on the sunken defects of the printed layer according to the defect sunken information, thereby effectively avoiding the influence of the raised defects on the subsequent in-situ secondary powdering of the pits produced by the sunken defects.

[0130] Specifically, the parameters for picosecond laser subtractive processing include: frequency of 100KHz, laser power of 5-15W, scanning speed of 100-500mm / s, and spot diameter of 15-35μm.

[0131] In one specific embodiment, the picosecond laser output mechanism 4 can output four picosecond laser beams, and the multi-flat-top laser output mechanism can output two flat-top beams.

[0132] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An ultra-precision additive and subtractive material area printing method, characterized in that: include: Establish a three-dimensional model of the part to be molded; The three-dimensional model is sliced ​​layer by layer to obtain multiple printing layers; Print layer by layer according to the multi-layer printing layer; Wherein, during the printing process of each printing layer, the powder is laid according to the information of the printing layer; When the powder is laid, the powder is regionally printed using multiple flat-top beams; When the area is printed, the three-dimensional contour of the printed layer is obtained; Generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer; Performing defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information; According to the defect detection result, the printed layer is subjected to defect reduction processing; Keep the height of the printing layer unchanged and perform secondary powder spreading in situ; After the second powder laying is completed, a picosecond laser is used to perform secondary additive manufacturing on the concave defects in the printed layer that have been processed by subtractive processing.

2. The ultra-precision additive and subtractive material area printing method according to claim 1, characterized in that: After performing secondary additive manufacturing on the subtractively processed concave defect in the printed layer using a picosecond laser, the method further includes: The printed layer is remelted in situ using a high repetition rate picosecond laser; Preferably, the parameters for in-situ remelting using a high repetition rate picosecond laser include: a frequency of 3-5 MHz, a laser power of 3-10 W, a scanning speed of 20-100 mm / s, and a spot diameter of 15-35 μm.

3. The ultra-precision additive and subtractive material area printing method according to claim 1, characterized in that: Obtain the three-dimensional profile of the printing layer, including: A laser three-dimensional imager is used to obtain the three-dimensional profile of the printed layer.

4. The ultra-precision additive and subtractive material area printing method according to claim 1, characterized in that: Perform defect detection on the three-dimensional contour model of the printed layer to obtain defect detection results, including: Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers; Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers; According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained. According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

5. The ultra-precision additive and subtractive material area printing method according to claim 4, characterized in that: Determining a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer with a convex defect, and a three-dimensional contour slice layer with a concave defect from a plurality of three-dimensional contour slice layers specifically includes: respectively obtaining the solidity ratios of a plurality of three-dimensional contour slice layers; In the direction from top to bottom, the first 3D contour slice layer with a solidity greater than 99% is defined as a reference layer; the 3D contour slice layer with a solidity less than 99% is determined as a 3D contour slice layer with convex defects; the remaining 3D contour slice layers with a solidity greater than 99% are determined as 3D contour slice layers with concave defects; Among them, the protrusion defects include spheroidization, humps and unmelted particles, and the concave defects include microcracks, pores and bubbles.

6. The ultra-precision additive and subtractive material area printing method according to claim 1, characterized in that: According to the defect detection results, the printed layer is subjected to defect reduction processing, specifically including: Using a picosecond laser to perform subtractive processing on the convex defects of the printing layer according to the convex defect information; Using picosecond laser to perform subtractive processing on the concave defect of the printed layer according to the defect concave information; Preferably, the parameters for the picosecond laser for subtractive processing include: a frequency of 100 KHz, a laser power of 5-15 W, a scanning speed of 100-500 mm / s, and a spot diameter of 15-35 μm; Preferably, the parameters of the picosecond laser for secondary additive manufacturing include: a frequency of 1-20 MHz, a laser power of 5-10 W, a scanning speed of 40-100 mm / s, and a spot diameter of 15-35 μm.

7. An ultra-precision additive and subtractive material area printing device, characterized in that: include: A three-dimensional scanning mechanism, a picosecond laser output mechanism, a multi-flat-top laser output mechanism, a molding mechanism, a defect detection mechanism and a control mechanism; the three-dimensional scanning mechanism, the picosecond laser output mechanism, the multi-flat-top laser output mechanism, the molding mechanism and the defect detection mechanism are electrically connected to the control mechanism respectively, and the control mechanism is used to control the three-dimensional scanning mechanism, the picosecond laser output mechanism, the multiple flat-top laser output mechanisms, the molding mechanism and the defect detection mechanism to coordinate actions to realize layer-by-layer printing of multiple printing layers; Wherein, during the printing process of each printing layer, the control mechanism is used to control the scraper of the molding mechanism to spread powder on the molding substrate of the molding mechanism; When the powder spreading is completed, the control mechanism is used to control the multi-flat-top laser output mechanism to perform regional printing; When the area printing is completed, the control mechanism is used to control the three-dimensional scanning mechanism to obtain the three-dimensional contour of the printing layer; The control mechanism is also used to generate a three-dimensional contour model of the printing layer according to the three-dimensional contour of the printing layer; The control mechanism is also used to control the defect detection mechanism to perform defect detection on the three-dimensional contour model of the printing layer to obtain defect detection results; wherein the defect detection results include convex defect information and concave defect information; The control mechanism is also used to control the picosecond laser output mechanism to output the picosecond laser to perform defect reduction processing on the printed layer according to the defect detection result; When the defect reduction processing is completed, the control mechanism is also used to control the height of the molding substrate of the molding mechanism to remain stationary, and at the same time control the scraper to perform secondary powder spreading in situ to fill powder into the concave defects in the printing layer that have undergone defect reduction processing; When the secondary powder spreading is completed, the control mechanism is also used to control the picosecond laser output mechanism to perform secondary additive manufacturing on the concave defects in the printing layer that have been subjected to subtractive processing.

8. The ultra-precision additive and subtractive material area printing device according to claim 7, characterized in that: The control mechanism is also used to control the picosecond laser output mechanism to output a high-repetition-rate picosecond laser to in-situ remelt the printed layer after controlling the picosecond laser output mechanism to perform secondary additive manufacturing on the recessed defects in the printed layer that have been subjected to subtractive processing.

9. The ultra-precision additive and subtractive material area printing device according to claim 7, characterized in that: The process of the control mechanism controlling the defect detection mechanism to perform defect detection specifically includes: Performing contour slicing on the three-dimensional contour model of the printing layer to obtain a plurality of three-dimensional contour slice layers; Determine a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer having a convex defect, and a three-dimensional contour slice layer having a concave defect from a plurality of three-dimensional contour slice layers; According to the three-dimensional contour slice layer with convex defects, the convex defect information is obtained. According to the three-dimensional contour slice layer with the concave defect, the concave defect information is obtained.

10. The ultra-precision additive and subtractive material area printing device according to claim 8, characterized in that: Determining a three-dimensional contour slice layer as a reference layer, a three-dimensional contour slice layer with a convex defect, and a three-dimensional contour slice layer with a concave defect from a plurality of three-dimensional contour slice layers specifically includes: respectively obtain the solidity ratios of multiple three-dimensional contour slice layers; In the direction from top to bottom, the first 3D contour slice layer with a solidity greater than 99% is defined as a reference layer; the 3D contour slice layer with a solidity less than 99% is determined as a 3D contour slice layer with convex defects; the remaining 3D contour slice layers with a solidity greater than 99% are determined as 3D contour slice layers with concave defects; Among them, the protrusion defects include spheroidization, humps and unmelted particles, and the concave defects include microcracks, pores and bubbles.

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