A method for manufacturing micro-parts based on additive and subtractive manufacturing processes and the micro-parts themselves.

Abstract

This invention relates to the field of additive and subtractive materials technology, specifically to a method for manufacturing micro-parts based on additive and subtractive materials, and the micro-parts themselves. The manufacturing method includes the following steps: using a first forming laser to print a first single-pass sprue on a current layer, obtaining a base with a curved surface; using a second forming laser to print a second single-pass sprue on the base, such that the second single-pass sprue is continuously formed on the base, and the structure formed by the second single-pass sprue constitutes the current layer of the part structure. The linear energy density of the second forming laser is lower than that of the first forming laser. This method enables the formation of continuous sprues with a low-energy-density laser, which is beneficial for forming high-precision micro-parts, and also has the advantages of easy operation and low cost.

Description

Technical Field

[0001] This invention relates to the field of additive and subtractive materials technology, and specifically to a method for manufacturing micro-parts based on additive and subtractive materials, and the micro-parts themselves. Background Technology

[0002] Multi-laser hybrid manufacturing, based on laser powder bed fusion (LPBF), is a smart manufacturing method that combines laser additive manufacturing and pulsed laser processing. Compared to LPBF, multi-laser hybrid manufacturing can process the internal structure and surface of unsealed parts, enabling the formation of more complex internal structures and achieving superior surface quality and microstructure.

[0003] "Micro-parts" refer to parts whose corresponding structures have a thickness extension between 10 μm and 500 μm in at least one spatial direction. Currently, additive manufacturing of "micro-parts," such as "thin-walled" structures, involves stacking single melt channels at the part's forming location. To obtain single melt channels with a narrower melt pool, the energy density of the melting laser must be reduced to obtain finer, more delicate parts. However, lower energy density lasers can cause unmelted powder, resulting in a large amount of powder adhering to the melt channel surface. Under the surface tension of the molten metal, the melt pool exhibits spheroidization, leading to discontinuities or even breaks in the single-channel surface (e.g., ...). Figure 1 As shown in the figure, continuous thermal stress cycles can cause excessive thermal stress in the melt channel, resulting in cracks.

[0004] The first layer of single-melt runners is formed on a flat substrate. Poor quality single-melt runners will affect the wettability of the melt pool in the next layer of stacked runners, thus affecting the forming quality. Ultimately, this affects the surface and side quality, density, and dimensional accuracy of the manufactured "thin-walled" structure, leading to deformation, cracking, or even failure to form the part. In existing technologies, the manufacture of thin-walled structures still uses a large number of supports, but removing the supports and the main body increases operational difficulties. Therefore, it is necessary to combine laser melting of metal with in-situ online detection technology, subtractive laser processing, and laser heat treatment to improve the quality of additive manufacturing of fine parts, reduce or even eliminate the use of a large number of support components, lower the minimum limit size of the formed parts, and manufacture more delicate and refined parts.

[0005] In response, Chinese patent (CN107685149B) discloses a method and apparatus for improving the forming quality of thin-walled parts in laser additive manufacturing. Although this apparatus can ensure that the laser deposition molten pool is always solidified and formed within the two ceramic blocks, and can overcome the limitation of the molten pool's limit size on the accuracy of the formed thin-walled parts, thus improving the surface quality of the thin-walled parts, this apparatus restricts the shape of the molten metal pool through mechanical structure limitations, without actually changing the fluidity and stability of the solution within a single molten pool. Severe adhesion may occur between the ceramic sheet and the molten metal pool, and the accuracy of the two ceramic sheets in the auxiliary forming system is difficult to meet the requirements of fine machining of thin-walled parts. The cost of constructing new equipment is high, and the strategy of adjusting the mechanical gripper and ceramic sheet at each layer greatly affects the printing efficiency, making it difficult to apply in practical engineering.

[0006] Chinese patent (CN114799229A) discloses a powder-spreading multi-laser additive and subtractive composite precision manufacturing device and its processing method. The device uses multiple continuous lasers for laser subtraction and uses visual inspection with an industrial camera to detect defects and roughness, reducing the possibility of internal defects in parts. However, the patent does not provide more detailed forming strategies and methods for the manufacturing process.

[0007] Chinese patent (CN116745050A) discloses a method for additively constructing discontinuous support members or support structures for supporting thin-walled structures on a building plate or platform, generating discontinuous molten pools in a powder bed to facilitate additive construction, particularly for thin-walled structures. However, this patent involves a large number of support members, which inevitably reduces production efficiency, and removing these support members is also quite difficult. Furthermore, this method does not reduce the limiting forming dimensions of thin-walled parts from the perspective of thin-wall forming, thereby reducing defects and improving the forming quality of thin-walled parts. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing micro parts based on additive and subtractive materials. This method can form a continuous melt channel with low energy density laser, which is beneficial for forming micro parts with high precision. It also has the advantages of being easy to operate and low cost.

[0009] The purpose of this invention is to provide a method for using a micro-part manufacturing method based on additive and subtractive materials.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A method for manufacturing micro-parts based on additive and subtractive manufacturing processes is provided, comprising the following steps:

[0012] The first single melt channel is printed on the current layer using a first forming laser to obtain a base with a curved surface;

[0013] A second forming laser is used to print a second single-melt track on the base, so that the second single-melt track is continuously formed on the base. The structure formed by the second single-melt track is the current layer of the part structure. The second forming laser is then used to form other single-melt tracks on the second single-melt track until the target micro-part is obtained.

[0014] The line energy density of the second shaping laser is lower than that of the first shaping laser.

[0015] The formula for calculating linear energy density is as follows:

[0016] El = p / v

[0017] E l —Linear energy density

[0018] p—laser power

[0019] v — scan speed.

[0020] In some embodiments, before forming the second single melt channel, a recessed microstructure is first formed on the surface of the base, so that the second single melt channel is formed on the recessed microstructure.

[0021] In some embodiments, the first shaping laser is a continuous laser with a linear energy density greater than 0.2, and the second shaping laser is a continuous laser or a pulsed laser.

[0022] In some embodiments, when the linear energy density of the first forming laser is in the range of [0.2 to 0.5), the cross-section of the base is spherical;

[0023] When the linear energy density of the first forming laser is [0.5~1.2), the cross-section of the base is flat-sloped.

[0024] In some embodiments, the continuous laser power is 10–1000 W, the scanning speed is 50–7000 mm / s, and the spot diameter is 10–300 micrometers;

[0025] The pulsed laser has a power range of 5–200W, a scanning speed of 50–5000 mm / s, a spot diameter of 5–200 micrometers, and a frequency of 20–5000 kHz.

[0026] In some implementations, a high-speed camera and / or an infrared thermal imaging camera are used. The high-speed camera and / or the infrared imaging camera are connected to an online monitoring processor and control module to form an in-situ detection device. The in-situ detection device detects the printing process and controls the laser parameters online.

[0027] In some implementations, during the printing process, a continuous laser is used to laser remelt and / or laser heat treat the current layer, the laser heat treatment eliminating thermal stress generated by additive manufacturing.

[0028] In some implementations, during the printing process, pulsed lasers are used to laser process the corresponding melt surface, perform surface pulsed laser shock blasting, or side laser cutting to refine the single melt morphology and remove diamond powder.

[0029] In some implementations, before printing, the micro-part model file is imported into a multi-laser additive and subtractive composite manufacturing equipment, and the required printing strategy is selected from a database based on the thickness of the micro-part.

[0030] In some implementations, the database is established in the following ways:

[0031] The state of the molten pool during printing is observed using a high-speed camera and an infrared thermal imaging camera. After printing, the cross-sectional state of the molten part is observed using an electron microscope and the corresponding laser parameters are recorded. The printing results and corresponding laser parameters are then stored in a database.

[0032] A micro-part is also provided, which is manufactured by the above-described additive-subtractive micro-part manufacturing method.

[0033] The beneficial effects of the present invention's method for manufacturing micro-parts based on additive and subtractive materials are as follows:

[0034] The present invention discloses a method for manufacturing micro-parts based on additive and subtractive materials. First, a high-energy-density first forming laser is used to form a first single melt channel on the current layer. Due to the high energy density of the first forming laser, the resulting first single melt channel is a continuous base with an arc surface. Based on this, a low-energy-density second forming laser is used to form a second single melt channel on this base for forming the thin-walled structure of the micro-part. Since the surface of the base formed by the first single melt channel has a certain curvature, this curvature can adjust the contact angle between the molten metal generated by the second forming laser and the base. This allows the molten metal pool formed by the low-density energy second forming laser, which has a small width, to be continuously and uniformly distributed on the base. This overcomes the problem of poor melt channel continuity caused by the small melt pool width in traditional low-density laser forming, which affects the accuracy of the formed thin-walled structure. Subsequently, the single melt channels superimposed on the base all have arc surfaces, allowing for the direct formation of a continuous thin-walled structure using a low-energy-density laser. Furthermore, the present invention can form the thin-walled structure of micro-parts without the need for support members, offering advantages such as ease of operation and low cost. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a small-sized, discontinuous single melt channel obtained by conventional line energy density laser.

[0036] Figure 2 This is the base formed by laser printing in the first embodiment of the present invention.

[0037] Figure 3 This is an illustration of the effect of the second forming laser forming a second single melt channel on the base according to an embodiment of the present invention.

[0038] Figure 4 This is a schematic diagram of the groove microstructure being processed on the first single melt channel according to an embodiment of the present invention.

[0039] Figure 5 This is a schematic diagram of processing a second single melt channel on a grooved microstructure according to an embodiment of the present invention.

[0040] Figure 6 This is a schematic diagram of the microstructure of the pit being processed on the first single melt channel according to an embodiment of the present invention.

[0041] Figure 7 This is a schematic diagram of processing a second single melt channel on a pit microstructure according to an embodiment of the present invention.

[0042] Figure 8 This is a schematic diagram of the first forming laser-printed spherical base and the single-channel printing of dot-shaped micropillars on the spherical base according to an embodiment of the present invention.

[0043] Figure 9 When the linear energy density of the first forming laser is in the range of [0.2~0.5), the corresponding cross-section is a spherical base;

[0044] Figure 10 The cross-section of the first forming laser is a sloping base when the linear energy density range is [0.5~1.2).

[0045] Figure 11 This is a schematic flowchart of a method for manufacturing micro-parts based on additive and subtractive materials according to an embodiment of the present invention.

[0046] Figure 12 This is an experimental diagram of a micropillar embodiment of the present invention.

[0047] Figure label:

[0048] 1. First forming laser; 2. First single melt channel; 3. Base; 4. Second forming laser; 5. Second single melt channel; 6. Recessed microstructure; 7. Spherical; 8. Flat slope; 9. Current layer. Detailed Implementation

[0049] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0050] Example

[0051] The manufacturing method for micro-parts based on additive and subtractive materials disclosed in this embodiment, such as... Figure 11 As shown, it includes the following steps:

[0052] The first single melt channel 2 is printed on the current layer 9 using the first forming laser 1 to obtain a base 3 with an arc surface;

[0053] Specifically, since the high line energy density laser has a large laser energy, the laser energy of the first forming laser 1 can ensure the continuity of the first single melt channel 2 and enable the first single melt channel 2 to form an arc-shaped structure on the current layer 9. This structure serves as the base 3 for printing and forming micro parts.

[0054] A second forming laser 4 is used to print a second single melt track 5 on the base 3, so that the second single melt track 5 is continuously formed on the base 3. The structure formed by the second single melt track 5 is the current layer 9 of the part structure. The line energy density of the second forming laser 4 is lower than that of the first forming laser 1. The line energy density is calculated using the following formula:

[0055] El = p / v

[0056] E l —Linear energy density

[0057] p—laser power

[0058] v — scan speed.

[0059] Specifically, since fine and delicate parts require the formation of a single melt channel with a small molten pool width, a low energy density laser is needed. Based on this, a second forming laser 4 with a low line energy density is used to form a single melt channel with a small molten pool width on the base 3. Although the line energy density of the second forming laser 4 is low, the curvature of the surface of the base 3 can change the solid-liquid contact angle between the molten metal solution in the molten pool and the base 3, thereby improving the stability of the molten pool, avoiding problems such as molten pool breakage, and improving the precision of the product.

[0060] After the current layer 9 (first layer) is prepared, the second forming laser 4 is used to form another single melt channel (such as...) on the second single melt channel 5. Figure 11The third single melt channel shown is also made using low line energy density, until the corresponding micro-parts are obtained.

[0061] For example, such as Figure 2 As shown, the first forming laser 1 prints a strip-shaped base 3, which has an arc shape, and then... Figure 3 As shown, the second forming laser 4 forms the second single melt channel 5 on the base 3.

[0062] Furthermore, such as Figure 8 As shown, the first forming laser 1 prints a spherical base 7 3 and prints dot-shaped micropillars on the spherical base 7 3 in a single pass.

[0063] This embodiment does not limit the shape of the base 3, as long as the base 3 with an arc is formed by the first forming laser 1.

[0064] In this embodiment, before forming the second single melt channel 5, a recessed microstructure 6 is first provided on the surface of the base 3 so that the second single melt channel 5 is formed on the recessed microstructure 6.

[0065] Specifically, forming recessed microstructures 6 on the surface of the base 3 helps the molten metal in the molten pool to adhere better to the surface of the base 3. The shape of the recessed microstructures 6 is not limited. For example, such as... Figure 4 As shown, a groove microstructure is machined on the second single melt channel 5, such as... Figure 6 The diagram shows a schematic of a microstructure with recesses fabricated on the first single melt channel 2. This microstructure can also be a rectangular groove, a square groove, a circular groove, a curved groove, a straight groove, or a mixed cross-groove; recess types include: circular recesses, square recesses, rectangular recesses, star-shaped recesses, and octagonal recesses; other types include: micro-column types, micro-conical types, crescent-shaped concave textures, crescent-shaped convex textures, multi-wedge channel structures, and sinusoidal structures, etc.

[0066] For example, such as Figure 5 As shown, a second single melt channel 5 is fabricated on the groove microstructure; as Figure 7 As shown, a second single melt channel 5 is fabricated on the pit microstructure.

[0067] In this embodiment, the first shaping laser 1 is a continuous laser with a linear energy density greater than 0.2, and the second shaping laser 4 is a continuous laser or a pulsed laser.

[0068] Specifically, a continuous laser is selected as the first forming laser 1. This continuous laser has high energy and can continuously form a single melt channel. Either a continuous laser or a pulsed laser is used as the second forming laser 4, as long as the line energy density can be controlled. To ensure the quality of the base 3 fabricated by the first forming laser 1, the line energy density of the first forming laser 1 is determined to be greater than 0.2.

[0069] In this embodiment, when the linear energy density of the first forming laser 1 is in the range of [0.2~0.5), the cross-section of the base 3 is spherical 7;

[0070] Specifically, such as Figure 9 As shown, when the linear energy density of the first forming laser 1 is in the range of [0.2~0.5), the corresponding cross section is spherical 7 base 3.

[0071] When the linear energy density of the first forming laser 1 is [0.5~1.2), the cross-section of the base 3 is flat slope 8.

[0072] Specifically, specifically, such as Figure 10 As shown, when the linear energy density of the first forming laser 1 is in the range of [0.5~1.2), the corresponding cross section is a sloped base 3.

[0073] Therefore, the curvature of the cross-section of the base 3 can be adjusted by adjusting the linear energy density of the first forming laser 1, thereby adjusting the degree of wetting between the molten metal obtained by the second forming laser 4 and the base 3, and realizing the controllability of the printing process.

[0074] In this embodiment, the continuous laser power is 10-1000W, the scanning speed is 50-7000mm / s, and the spot diameter is 10-300 micrometers;

[0075] The pulsed laser has a power range of 5–200W, a scanning speed of 50–5000 mm / s, a spot diameter of 5–200 micrometers, and a frequency of 20–5000 kHz.

[0076] The specific continuous laser parameters and pulsed laser parameters can be adjusted according to the actual situation.

[0077] In this embodiment, a high-speed camera and / or an infrared thermal imaging camera are used. The high-speed camera and / or the infrared imaging camera are connected to an online monitoring processor and control module to form an in-situ detection device. The in-situ detection device detects the printing process and controls the laser parameters online.

[0078] Specifically, this invention enables stress relief of the workpiece by heat treatment before or after manufacturing a specific number of layers during laser-assisted additive and subtractive material composite manufacturing. Furthermore, it combines an infrared thermal imaging camera with an online monitoring processor and control module to precisely control the heat treatment temperature and the subsequent annealing temperature.

[0079] In the manufacture of micro parts, the limitations of the above-mentioned conventional steps are not imposed. For the manufacture of extremely fine micro parts, pulsed lasers with small spot sizes can be used for additive manufacturing, while for micro parts with slightly larger dimensions and thicknesses, heat treatment lasers with large spot sizes can be used for additive manufacturing.

[0080] In this embodiment, during the printing process, a continuous laser is used to perform laser remelting and / or laser heat treatment on the current layer 9, and the laser heat treatment eliminates the thermal stress generated by additive manufacturing.

[0081] Specifically, during the printing process, an industrial camera is used to monitor the quality of the molten metal pool in a specific layer. Depending on the actual monitoring results, remelting of the molten metal pool using continuous laser or heat treatment laser can be performed to improve the surface structure. After printing a specific number of layers, continuous laser is used to perform laser heat treatment on the micro-parts to eliminate the thermal stress generated during additive manufacturing and improve their surface hardness, wear resistance, corrosion resistance, strength, and high-temperature performance.

[0082] In this embodiment, during the printing process, pulsed lasers are used to perform laser processing, surface pulsed laser shock strengthening, or side laser cutting on the corresponding melt surface to modify the single melt morphology and remove diamond powder.

[0083] Specifically, during the printing process, an industrial camera is used to monitor the quality of the molten metal pool in a specific layer. Based on the actual monitoring results, continuous laser or heat treatment laser remelting can be used to improve the surface structure. Pulsed lasers are used to perform laser processing on the surface of the corresponding molten pool, surface pulsed laser shock strengthening, and side laser cutting to correct the morphology of the single-pass molten pool, remove powder adhering to the surface side, reduce defects, refine the structure, increase the dislocation density, and thus improve the performance of additively manufactured parts.

[0084] In this embodiment, before printing, the micro-part model file is first imported into the multi-laser additive and subtractive composite manufacturing equipment, and the required printing strategy is selected from the database according to the thickness of the micro-part.

[0085] Specifically, in practical applications, the process begins by creating a model of the micro-parts, importing it into the additive-subtractive manufacturing equipment for printing, selecting a suitable manufacturing and processing combination strategy from the additive-subtractive manufacturing database based on the required width of the micro-parts, choosing the parameters of the corresponding strategy, and then starting the printing process.

[0086] In this embodiment, the database is established in the following ways:

[0087] The state of the molten pool during printing is observed using a high-speed camera and an infrared thermal imaging camera. After printing, the cross-sectional state of the molten part is observed using an electron microscope and the corresponding laser parameters are recorded. The printing results and corresponding laser parameters are then stored in a database.

[0088] Specifically, a database for base 3 is created: During the printing process, a high-speed camera and an infrared thermal imaging camera are used to observe the state of the molten pool during printing. For single-pass formed parts, a scanning electron microscope (SEM) is used to observe the surface morphology and forming quality of the single-pass parts, and the molten pool width of each single-pass is measured under various parameters. The cross-section of the formed single-pass parts is observed using an optical microscope, recording the cross-sectional shape, curvature, molten pool height, cross-sectional quality, molten pool depth, and wetting angle between the molten pool and the substrate under various laser parameters. An additive-subtractive composite manufacturing database is established, recording single-pass quality data and their corresponding forming laser types. The forming parameters are stored in the additive-subtractive composite manufacturing database—single-pass part library.

[0089] A database for the second melt channel on base 3 was created: During the printing process, a high-speed camera and an infrared thermal imaging camera were used to monitor the state of the molten pool. The surface morphology and forming quality of the formed dual-melt channel parts were observed using a scanning electron microscope (SEM), and the width of the molten pool of the second single melt channel 5 under different base 3-second layer combinations was measured. The cross-section of the dual-melt channel parts was observed using an optical microscope, and the shape, depth, height, curvature, and wetting angle between the base 3 and the second melt channel 5 were recorded for each different combination. The changes in molten pool stability between the single-melt channel parts and the base 3-second layer combination parts under the same parameters were analyzed. The data for each base 3-second layer combination were recorded and stored in the additive-subtractive composite manufacturing database—dual-melt channel parts database.

[0090] A microstructure database was created: Three models for evaluating solid surface wettability—the Young state model, the Wenzel state model, and the Cassie-Baxter state model—were used to analyze the wetting angle and its variation in the molten pool of the second single melt channel 5 after microstructure processing, as well as the stability of the molten pool. The continuity, width, powder adhesion, defect type and quantity, cross-sectional height, depth, curvature, shape, and defect occurrence of the second-layer molten pool surface were observed. A micro-part processing strategy was developed that organically combines the base 3, microtexture, and second layer. Parts manufactured using the base 3-second-layer processing strategy described in the "Creating a Second Melt Channel Database on Base 3" were compared, and parts with excellent second-layer molten pool quality were selected. Their quality and shape data, as well as laser type and parameters, were recorded and stored in the additive-subtractive composite manufacturing database.

[0091] This process is repeated, continuously verifying and collecting data to obtain the corresponding database.

[0092] Test case

[0093] To further illustrate the performance of the micro-parts obtained by the manufacturing method of the present invention, the following experimental examples were conducted:

[0094] Step 1: Prepare the micro-part model file and prepare for printing using the multi-laser additive and subtractive composite manufacturing equipment. Select the forming laser type and parameters for each melt channel based on the required thickness of the micro-parts to be manufactured, as well as the subtractive pulse laser type and parameters. In the first melt channel forming, select continuous laser forming. Choose the continuous laser parameters according to the required fine thickness of the thin-walled part: spot diameter: 10-300 micrometers, continuous laser power: 10-1000W, scanning speed: 50-7000mm / s. Calculate the energy density using the laser line energy density E=P / V, where E is the laser line energy density, P is the laser power, and V is the scanning speed. Select a high line energy density (greater than 0.2) laser power and scanning speed combination to form a stable and continuous bottom single melt channel base 3. The base 3 formed has two cross-sectional types: flat slope 8 (linear energy density 0.55-1.5) and hemispherical 7 (linear energy density 0.2-0.55). When the size of the manufactured fine parts is 10-80 micrometers, the hemispherical 7 single melt channel base 3 is used, and when it is 80-300 micrometers, the flat slope 8 single melt channel base 3 is used.

[0095] Step 2: Use a pulsed laser to process microstructures such as grooves and pits on a single melt path. Select the pulsed laser parameters based on the type, size, and processing depth of the microstructure. Pulsed laser parameter selection range: pulsed laser power range 5–200W, fastest scanning speed 50–5000 mm / s, spot diameter 5–200 micrometers, frequency 20–5000 kHz, and select the number of scans based on the depth.

[0096] Step 3: On the single-melt-track base 3 after the microstructure has been processed, a second single-melt-track 5 is formed using a continuous laser or pulsed laser. The laser type and corresponding laser parameters for the second single-melt-track 5 are selected according to the micro-part being manufactured, ensuring that the size of the second single-melt-track 5 matches the final size of the micro-part to be formed. For micro-parts with a size of 5-50 micrometers, pulsed laser additive manufacturing is used (pulsed lasers have a smaller spot diameter, resulting in a smaller molten pool). For micro-parts with a size of 50-150 micrometers, a low-energy-density (linear energy density 0.1-0.2) continuous laser is used to form the second single-melt-track 5. For micro-parts with a size of 150-300 micrometers, a continuous laser with a linear energy density of 0.2-0.5 is selected. The appropriate spot diameter is selected based on the size of the micro-part to be formed, and the spot diameter should be close to the size of the micro-part to be formed. (Because the second single melt channel 5 is stacked on the base 3, compared with the melt channel of directly molding fine parts on a flat substrate, the solid-liquid contact angle (wetting angle) of the single melt channel stacked on the base 3 is smaller (less than 90 degrees), the stability of the second single melt channel 5 is improved, the melt channel is more continuous, and the quality is higher.)

[0097] Step 4: Use a pulsed laser to remove powder adhering to the surface of the second single melt channel 5 and correct the edges of the melt channel. If necessary, use a pulsed laser to process microstructures on the second single melt channel 5 (the reasonable arrangement of microstructures can further change the solid-liquid contact angle when the two melt channels are stacked, and improve the stability of the metal pool of the upper melt channel).

[0098] Step 5: Repeat steps 3 and 4 until the fine parts are formed, resulting in the following: Figure 12 The tiny parts shown are from Figure 12 As can be seen, the micro-part can have a micro-pillar with a length of 534.806 μm, and the micro-pillar is a continuous structure. It is evident that the manufacturing method of the present invention can produce a continuous thin-walled structure.

[0099] It is best to use a pulsed laser to laser polish the upper surface of the part.

[0100] For the manufacture of extremely fine micro-parts, this invention typically employs a process where a forming laser melts powder to form a single melt channel, which is then stacked on top of each other. To further reduce the thickness of thin-walled parts, the energy density of the forming laser needs to be reduced, resulting in a smaller molten pool width for each single melt channel. However, reducing the energy density of the forming laser leads to incomplete powder melting, increasing the amount of unmelted powder that adheres to the surface of the melt channel. Furthermore, under the influence of surface tension and the viscosity of the molten metal, an unstable molten pool can develop spheroidization defects, causing discontinuous melt channels. To address these issues, before printing extremely fine micro-parts, a high-energy-density forming laser is used to create a single melt channel with a large and stable continuous molten pool, serving as the base 3 for micro-manufacturing. Then, based on the stable molten pool base 3, a low-energy-density laser is used to create a single melt channel with a smaller molten pool width. Due to the change in the solid-liquid contact angle, the stability of the original molten pool is improved, resulting in a single melt channel with a small and stable continuous molten pool. Using high-speed cameras and industrial cameras to monitor the printing process online, pulsed lasers can be used to remove powder from the edges of the melt path and correct the melt path at specific layers.

[0101] For parts requiring two different fine dimensions, after forming a single melt channel base 3 by forming laser, a pulsed laser is used to process a micro-texture on the surface of the base 3, which is beneficial to reduce the molten pool wetting angle and improve the stability of the molten pool. A single melt channel with a finer size is then superimposed on the base 3 with the micro-texture. During the printing process, a large spot continuous laser can be used to heat treat the surface of the part to remove thermal stress.

[0102] For parts with columnar fine structures, a high-energy-density forming laser is used with a closed-loop scanning single-pass strategy to form a hemispherical 7-layer molten pool base 3. A pulsed laser is then used to process microtextures on the curved surface of the spherical 7-layer base 3, which are beneficial to the stability of the molten pool. On top of the stable spherical 7-layer base 3, single passes of small-sized molten pools are stacked using the same closed-loop scanning strategy. During the printing process, high-speed cameras and industrial cameras are used for online monitoring, and pulsed lasers are used to remove powder from the sides of the layer. Microtextures can also be processed on each layer using pulsed lasers as needed to improve the stability of the lower molten pool, resulting in parts with superior quality and finer dimensions.

[0103] This invention, from the perspective of the molten pool, modifies the curvature of the underlying base 3 through additive and subtractive laser composite manufacturing, thereby altering the solid-liquid contact angle between the molten metal and the solid, and improving the stability of the molten metal pool. By superimposing single melt channels on the stable base 3, the quality of single melt channel parts, which were originally poor and difficult to form at lower laser energy densities, can be significantly improved. This results in single melt channels with smaller molten pool widths, reducing the limiting dimensions for part forming and enabling the manufacture of more refined parts.

[0104] This invention combines in-situ online detection technologies using continuous laser, pulsed laser, high-speed camera, and infrared thermal imaging camera. Continuous laser is used to manufacture single-channel molten pool bases 3 with varying shapes and curvatures. Subsequently, pulsed laser is used to finely process the structural morphology of the base 3, establishing a database to record the single-channel molten pool morphology under various laser parameters for adding or subtracting materials. Single-channel molten pools are then superimposed on the single-channel molten pool bases 3 with different surface morphologies, surface microstructures, and cross-sectional curvatures, and online detection is performed using a high-speed camera and an infrared thermal imaging camera. This allows for the acquisition of the optimal combination of base 3 morphology and surface microstructure, as well as the optimal combination of base 3 parameters and micro-part parameters for manufacturing micro-parts of specific thicknesses.

[0105] The combined use of continuous and pulsed lasers in manufacturing allows for cutting within unsealed parts using pulsed lasers, enabling the correction of the molten pool morphology. After additive manufacturing with a specific number of layers, pulsed lasers can be used to remove adhering powder from the sides of the parts, significantly improving the side quality and density of micro-parts. Part surfaces can also be laser-polished and laser shock-strengthened using pulsed lasers.

[0106] This invention enables stress relief of workpieces by heat treatment before or after manufacturing specific layers during laser-assisted additive and subtractive material composite manufacturing. Furthermore, it combines an infrared thermal imaging camera with an online monitoring processor and control module to precisely control the heat treatment temperature and the subsequent annealing temperature.

[0107] This invention is not limited by the conventional steps mentioned above in the manufacture of micro parts. In the manufacture of extremely fine micro parts, a pulsed laser with a small spot size can be used for additive manufacturing, while for micro parts with a slightly larger size and thickness, a heat treatment laser with a large spot size can be used for additive manufacturing.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing micro-parts based on additive and subtractive materials, characterized in that, Includes the following steps: The first single melt channel is printed on the current layer using a first forming laser to obtain a base with a curved surface; A second forming laser is used to print a second single-melt track on the base, so that the second single-melt track is continuously formed on the base. The structure formed by the second single-melt track is the current layer of the part structure. The second forming laser is then used to form other single-melt tracks on the second single-melt track until the target micro-part is obtained. The line energy density of the second shaping laser is lower than that of the first shaping laser. The formula for calculating linear energy density is as follows: E l =p / v E l —Linear energy density p—laser power v—scanning speed; Before forming the second single melt channel, a recessed microstructure is first set on the surface of the base, so that the second single melt channel is formed on the recessed microstructure. The first shaping laser is a continuous laser, and the linear energy density value of the first shaping laser is greater than 0.

2. The second shaping laser is a continuous laser or a pulsed laser. When the linear energy density of the first forming laser is in the range of [0.2~0.5), the cross-section of the base is spherical; When the linear energy density of the first forming laser is [0.5~1.2), the cross-section of the base is flat and sloping; the continuous laser power is 10~1000W, the scanning speed is 50~7000mm / s, and the spot diameter is 10~300 micrometers. The pulsed laser has a power range of 5–200W, a scanning speed of 50–5000 mm / s, a spot diameter of 5–200 micrometers, and a frequency of 20–5000 kHz.

2. The method for manufacturing micro-parts based on additive and subtractive materials according to claim 1, characterized in that, A high-speed camera and / or an infrared thermal imaging camera are used. The high-speed camera and / or the infrared thermal imaging camera are connected to an online monitoring processor and a control module to form an in-situ detection device. The in-situ detection device detects the printing process and controls the laser parameters online.

3. The method for manufacturing micro-parts based on additive and subtractive materials according to claim 2, characterized in that, During the printing process, a continuous laser is used to laser remelt and / or laser heat treat the current layer, the laser heat treatment eliminating the thermal stress generated by additive manufacturing.

4. The method for manufacturing micro-parts based on additive and subtractive materials according to claim 3, characterized in that, During the printing process, pulsed lasers are used to perform laser processing, surface pulsed laser shock strengthening, or side laser cutting on the corresponding melt track surface to modify the shape of the single melt track and remove powder.

5. The method for manufacturing micro-parts based on additive and subtractive materials according to claim 4, characterized in that, Before printing, the micro-part model file is imported into the multi-laser additive and subtractive composite manufacturing equipment, and the required printing strategy is selected from the database according to the thickness of the micro-part.

6. The method for manufacturing micro-parts based on additive and subtractive materials according to claim 5, characterized in that, The database can be established in the following ways: The state of the molten pool during printing is observed using a high-speed camera and an infrared thermal imaging camera. After printing, the cross-sectional state of the molten part is observed using an electron microscope and the corresponding laser parameters are recorded. The printing results and corresponding laser parameters are then stored in a database.

7. A micro-part, characterized in that, The micro-parts are manufactured by the micro-parts manufacturing method based on additive or subtractive materials as described in any one of claims 1 to 6.

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