A scanning laser printhead

Abstract

This invention relates to a printhead for 3D printing, particularly a printhead based on scanning laser heating, belonging to the field of additive manufacturing technology. Compared with existing coaxial filament feeding laser cladding heads / printheads, this invention offers significant advantages, such as: enabling flexible heating strategies; supporting the printing of finer structures; avoiding overheating of freshly deposited material; providing extremely high tolerance for mechanical assembly precision between the laser path's mechanical structure and other parts of the printhead; creating a stirring effect on the molten pool, improving the performance of the final 3D printed part; preheating the area where material will be deposited, reducing the temperature gradient between the molten pool area and other areas of the workpiece, thereby suppressing thermal cracking; and integrating laser cleaning during the 3D printing process, enabling 3D printing in air without the use of protective gases, resulting in lower costs. This invention represents a significant and substantial advancement.

Description

Technical Field

[0001] This invention relates to a printhead for 3D printing, and more particularly to a printhead based on scanning laser heating, belonging to the field of additive manufacturing technology. Background Technology

[0002] 3D printing, also known as additive manufacturing, is a major category of advanced manufacturing technologies. 3D printing uses various forms of raw materials, such as liquids, solid powders, granules, filaments, rods, and wires. Among these, filaments are often cheaper, easier to store, safer, and more environmentally friendly than powders. Existing 3D printing technologies that use lasers as a heating source and filaments as raw materials include two types: "off-axis filament feeding" and "coaxial filament feeding." For example, the technical solution disclosed in Chinese patent application number 2018800071130 adopts a "side-axis wire feeding" method. In this technology, the laser beam is perpendicular to the current forming surface, and the filament is transported from outside the space enclosed by the laser beam to the surface of the workpiece (also known as the printed body, which is an object formed after the molten raw material is deposited). The laser beam melts the filament and the area of ​​the workpiece surface adjacent to the filament together. This method does not need to consider the problem of the filament blocking the laser, and the optical path structure is relatively simple. However, it has problems such as directional defects in printing, difficulty in printing path planning, complex programming of multi-axis motion platforms, low surface quality of parts, low printing efficiency, and difficulty in printing complex structures. The paper entitled "A Comprehensive Study of Auxiliary Arrangements for Attaining Omnidirectionality in Additive Manufacturing Machine Tools" (DOI:10.1115 / 1.4049094) discusses the directional problems faced by "side-axis wire feeding" in additive manufacturing. In order to solve the problems of the wire blocking the laser beam and being heated and melted too early, the "coaxial wire feeding method" generally expands the laser beam first, then shapes it into a ring laser beam (hollow laser beam), the wire passes through the center of the ring laser beam, and then the ring laser beam is focused, and the wire melts near the focal point of the laser beam. For example, the technical solutions disclosed in Chinese patent applications with application numbers 2018103767579 and 2018104031543 adopt a "coaxial wire feeding" method. There is no laser in the axial space of the laser beam (i.e., the center of the laser beam). The wire is transported to the surface of the workpiece along the center of the laser beam. The laser beam is focused on the surface of the workpiece and melts the wire and the area of ​​the workpiece surface adjacent to the wire. The optical path of this method is more complex and the optical path is more difficult to manufacture than that of the off-axis wire feeding method. However, since the wire is perpendicular to the surface of the workpiece where the molten material is accumulating (also known as depositing), the wire and the laser beam can print together on the surface of the workpiece in any direction. This solves the directional problem caused by the traditional off-axis wire feeding method. It also has many advantages that are not easy to obtain by off-axis wire feeding, such as simple printing path planning, simple required motion platform structure, simple program programming, higher part surface quality, and the ability to print complex structures. Summary of the Invention

[0003] The inventors discovered that in existing coaxial filament feeding methods, the positional relationship between the laser beam and the filament, as well as the relative positional relationship between the laser spot and the filament or the molten material generated by the filament, is relatively fixed. This results in a lack of printing flexibility. Specifically, for example, in the metal 3D printing process, the metal filament is heated and melted and deposited on the workpiece. Immediately after the molten metal is deposited, it is heated by the annular laser spot projected onto the workpiece surface. The deposited molten metal is overheated, leading to increased fluidity. This increased fluidity further results in problems such as low shape controllability, rough surface morphology, and low forming accuracy. Overheating also leads to increased evaporation and increased porosity. To avoid heating the newly deposited molten metal, the laser beam needs to be able to quickly adjust the position of the laser spot around the molten metal according to changes in the printing path. However, existing laser coaxial filament feeding 3D printing technology does not possess this flexibility. For example, in the metal 3D printing process, the annular spot of the laser beam projected onto the workpiece and surrounding the molten metal also heats areas not on the printing path, resulting in a large molten pool and a large heat-affected zone. When printing delicate structures such as thin-walled structures with slow heat dissipation, this can lead to overheating, damage, or deformation. An ideal heating method would be to heat the area in front of the printing path, with the width of the molten pool roughly matching the width of the thin-walled structure. This requires the laser beam to be able to quickly adjust the spot position according to changes in the printing path, a flexibility that existing coaxial laser wire-feeding 3D printing technology lacks. These existing problems stem from the limitations of the annular spot laser head used in coaxial laser wire-feeding 3D printing technology. Annular spot laser heads can also be applied to laser welding systems, but they also suffer from the same limitations. Furthermore, since the existing laser "coaxial wire feeding" heating method is the same as the "heat conduction method" of laser welding, the laser spot power density is the same as that of traditional heat conduction laser welding. The spot power density value cannot cause significant vaporization of the heated workpiece or raw material, otherwise it will seriously harm the 3D printing process. Therefore, it is impossible to achieve the "laser cleaning" function by increasing the spot power density.

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a laser printhead (also known as a laser cladding head) that uses one or more laser beams to heat the printhead by scanning, which can flexibly perform scanning laser heating, and is different from the existing "coaxial wire feeding" laser cladding head / printhead.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention is as follows:

[0006] A scanning laser printhead, characterized in that:

[0007] The system is equipped with a laser interface, a reflector, a focusing lens, and a material conveying channel. The laser beam from the laser interface is modulated by the reflector and the focusing lens and then projected onto the workpiece from the space surrounding the material conveying channel. The material required for printing arrives at the workpiece via the material conveying channel. The material can be liquid or solid. Molten material formed by melting liquid or solid material is deposited on the workpiece.

[0008] The reflector is rotatable and / or movable to modulate the position of the laser beam projected onto the workpiece, and / or the focusing lens is rotatable and / or movable to modulate the position of the laser beam projected onto the workpiece, thereby causing the laser beam to scan and heat the edges and / or periphery of the area on the workpiece where material is being deposited; while the laser beam scans and heats the edges and / or periphery of the area on the workpiece where material is being deposited, the scanning and heating area of ​​the laser beam on the workpiece also moves relative to the workpiece; (Explanation: In the 3D printing process, the print head moves relative to the workpiece, and the scanning and heating area of ​​the laser beam on the workpiece also moves relative to the workpiece;)

[0009] The number of laser beams that can be projected is at least two; each laser beam can be controlled independently; the number of laser beams projected at the same time is controllable;

[0010] The area where the raw material is being deposited refers to the area on the workpiece that is in contact with the raw material being deposited;

[0011] The edge of the area where the raw material is being deposited refers to the edge of the area on the workpiece that is in contact with the raw material being deposited.

[0012] The periphery of the area where the raw material is being deposited refers to the area on the workpiece that is adjacent to or connected to the area where the raw material is being deposited.

[0013] (Explanation: "Raw material being deposited" refers to raw material that has already come into contact with the workpiece and is located in the space between the outlet of the raw material conveying channel and the workpiece.)

[0014] Optional:

[0015] When the raw material is solid, the laser beam also heats the solid raw material outside the outlet of the raw material conveying channel to generate molten raw material in the space between the outlet of the raw material conveying channel and the workpiece.

[0016] Optional:

[0017] When two or more laser beams are simultaneously projected onto a workpiece, the laser beam spot scanning area projected onto the workpiece can form a composite scanning area, which can surround the area on the workpiece where the raw material is being deposited.

[0018] Optional:

[0019] The laser beam scans and heats the edge and / or periphery of the area on the workpiece where the raw material is being deposited, to generate a molten pool;

[0020] When the number of projected laser beams is two or more, the power of each laser beam can be controlled independently;

[0021] When the number of projected laser beams is two or more, the scanning parameters of each laser beam can be controlled independently.

[0022] Optional:

[0023] The number of reflectors is at least two;

[0024] The number of focusing lenses is at least one, and the number of focusing lenses is the same as the number of laser beams, with one focusing lens corresponding to each laser beam; or, the number of focusing lenses is one, and each laser beam passes through the focusing lens; (for example, two laser beams share one annular focusing lens).

[0025] Optional:

[0026] The focusing lens mentioned is either a field lens or a non-field lens; (Here, a field lens, also called a flat field lens or f-theta lens, is a specialized lens system whose function is to form a uniformly sized focused spot of the laser beam across the entire marking plane, and is one of the most important components of a laser marking machine.)

[0027] The reflector is driven by electromagnetic force (e.g., electric motor, electromagnet, etc.), or by piezoelectric element (e.g., piezoelectric ceramic), or by thermo-deformation (e.g., a drive mechanism using thermo-deformation material as the drive component), or by magneto-deformation (e.g., a drive mechanism using magneto-deformation material as the drive component), or by electro-deformation (e.g., a drive mechanism using electro-deformation material as the drive component), or by fluid (e.g., cylinder, hydraulic push rod, etc.).

[0028] Optional:

[0029] The reflector is located either before or after the focusing lens in the laser propagation path.

[0030] Optional:

[0031] A collimating lens is provided to convert a non-parallel laser beam into a parallel laser beam. The collimating lens is located before the laser interface in the propagation path of the laser beam.

[0032] A beam splitter is provided to split a laser beam into at least two beams, and the beam splitter is located before the laser interface in the propagation path of the laser beams.

[0033] A window mirror is provided to prevent external substances from contacting the reflector and focusing mirror at the laser emission port;

[0034] A gas passage is provided for spraying gas to form an air curtain to prevent or reduce external contamination of the reflector, focusing lens and window lens, and / or to spray protective gas onto the molten raw material and the molten pool on the workpiece to form a protective atmosphere.

[0035] A liquid cooling channel is provided for cooling the scanning laser printhead;

[0036] It is equipped with an optical path switching component to switch the laser beam from one laser interface to another (for example, using a motor to drive a reflector to control the propagation path of the laser and achieve "time-division multiplexing").

[0037] Optional:

[0038] The reflector can be translated or rotated in one dimension to move the laser beam in one dimension; or, the reflector can be translated or rotated in two dimensions to move the laser beam in two dimensions (in this case, when the focusing lens is electrically adjustable and programmable, scanning is performed in the X and Y axes by the reflector, and scanning is performed in the Z axis by adjusting the focusing lens, thereby enabling the focal point of the laser beam to be scanned in three-dimensional space).

[0039] Optional:

[0040] The focusing lens can be translated or rotated in one dimension to move the laser beam in one dimension (also known as one-dimensional scanning); or, the focusing lens can be translated or rotated in two dimensions to move the laser beam in two dimensions (also known as two-dimensional scanning); or, the focusing lens can be translated or rotated in two dimensions to move the laser beam in one dimension and to focus the focusing lens; or, the focusing lens can be translated or rotated in three dimensions to move the laser beam in two dimensions and to focus the focusing lens (in this case, when the focusing lens can be electrically focused and programmably focused, it can scan in the X and Y axis directions through the focusing lens, and also scan in the Z axis direction through focusing the focusing lens, thereby realizing the scanning of the focal point of the laser beam in three-dimensional space, i.e., realizing three-dimensional scanning), thus changing both the planar scanning position of the light spot on the workpiece surface and the area of ​​the light spot on the workpiece surface.

[0041] Optional:

[0042] The focusing lens is adjustable, and the focusing method can be manual focusing, electric focusing, pneumatic focusing, or hydraulic focusing.

[0043] Optional:

[0044] The laser interface is connected to the laser output head of the laser.

[0045] Optional:

[0046] The laser beam can scan and heat the surrounding annular region or a portion of the annular region where the raw material is being deposited.

[0047] Optional:

[0048] The number of projected laser beams is at least two. One portion of the laser beam scans and heats the edges and / or periphery of the area on the workpiece where the raw material is being deposited to create a molten pool. The other portion of the laser beam modifies the shape of the already printed surface of the workpiece, for example, by performing laser cutting, laser engraving, or laser cleaning (e.g., cleaning oxide film) on areas of the workpiece that are not currently deposited with raw material, in order to obtain better surface quality and adjust the structure of certain areas of the workpiece (e.g., modifying the wall thickness).

[0049] Optional:

[0050] The reflector and / or focusing lens control the laser beam to heat the edge of the material being deposited, thereby conducting heat through the material to the edge of the area on the workpiece where the material is being deposited, thus indirectly scanning and heating the edge of the area on the workpiece where the material is being deposited. (Explanation: When the area where the material is being deposited is in contact with the material being deposited, causing the area to be covered by the material, the laser beam cannot directly heat the area on the workpiece surface covered by the material. It is necessary to heat the material being deposited, and then conduct heat through the material to the area where the material is being deposited for indirect heating. Of course, if the laser beam directly heats the periphery of the area where the material is being deposited that is connected to or adjacent to the edge of the area where the material is being deposited, the heat from that periphery will also be transferred to the edge of the area where the material is being deposited through heat conduction, thus also indirectly heating the edge of the area where the material is being deposited.)

[0051] Optional:

[0052] The aforementioned reflector and / or focusing lens control the laser beam to scan and heat the periphery of the area on the printed body (workpiece) where the raw material is being deposited, and its scanning parameters can be dynamically adjusted. Throughout the printing process of a part, the laser scanning heating parameters are not fixed. When printing different areas of a part, parameters such as the width of the scanning area, the degree of overlap between the scanning area and the area on the printed body where the raw material is being deposited, the scanning line density within the scanning area, and the power can be adjusted as needed. For example, when printing a part, it needs to be built on a base plate (support plate) because the first layer is tightly connected to the base plate, providing good heat dissipation. Printing the first layer requires the maximum heating power and a large scanning range. As the printing height increases, the heat dissipation conditions worsen, and the scanning parameters also need to be adjusted. Similarly, when printing thin-walled structures, the scanning range and heating power are smaller than for thick-walled structures. Furthermore, the scanning parameters required for printing edge structures with sharp corners are different from those required for printing structures in non-edge locations.

[0053] Optional:

[0054] The area on the raw material deposition path of the workpiece that is to be scanned and heated by the laser beam can be preheated before it is to be scanned and heated by the laser beam, and the range of preheating can be set.

[0055] Optional:

[0056] The reflector and / or focusing lens control the laser beam to heat the material being deposited while simultaneously scanning and heating the edge and / or periphery of the area where the material is being deposited.

[0057] Optional:

[0058] The laser beam scans and heats the interface between the workpiece surface and the raw material being deposited, thereby performing laser cleaning on the interface.

[0059] The main beneficial effects of this invention are as follows:

[0060] (1) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention can also obtain an annular spot to heat the edge and / or periphery of the area on the workpiece where the raw material is being deposited, but the present invention is more flexible.

[0061] (2) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention can achieve a flexible heating strategy by adjusting the scanning position of the laser beam spot during the three-dimensional printing process. For example, two lasers are used, one of which is responsible for heating the area of ​​the printed body (i.e. the workpiece) that is connected to or adjacent to the area where the raw material is being deposited in front of the printing path with high power, while the other laser only heats the surface of the printed body and the raw material that has just been deposited with low power to obtain a smoother surface and avoid serious problems (such as significant vaporization) caused by overheating due to high power heating of the raw material that has just been deposited; or, according to the characteristics of the surrounding structure of the area where the raw material is accumulating, the scanning strategy corresponding to the minimum stress is calculated, and the scanning range and scanning path of the spot are dynamically adjusted.

[0062] (3) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention reduces the thermal influence range of the laser by adopting a laser scanning heating strategy that only heats the area of ​​the printed body surface located in front of the printing path and adjacent or connected areas when printing thin-walled structures, thereby avoiding overheating of thin-walled structures and reducing deformation. The present invention has more advantages when printing thin-walled structures and is more suitable for printing complex and fine structures.

[0063] (4) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention can also irradiate and heat the area on the workpiece surface where the raw material is about to be deposited (accumulated) without heating the raw material that has just been deposited. This avoids overheating the raw material that has just been deposited (overheating will lead to higher fluidity or vaporization), and can obtain higher molding accuracy. The part material has fewer micropores and higher density, which is of greater significance for additive manufacturing applications. Therefore, the present invention can be used for higher precision additive manufacturing.

[0064] (5) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention uses the rotation and / or movement of the reflector and / or focusing lens to control the dynamic scanning of the laser. The projection position of the laser beam is dynamically adjustable, and it has extremely high tolerance for the mechanical assembly accuracy between the optical path mechanical structure and the raw material conveying channel and other components.

[0065] (6) Compared with the existing "coaxial wire feeding" laser cladding head (print head), the present invention uses laser scanning to generate a molten pool on the printed body (workpiece). The "scanning method" can produce a "stirring" effect on the molten pool, which has a beneficial effect on the performance of the parts finally obtained by 3D printing, such as reducing micropores.

[0066] (7) Compared with existing coaxial filament feeding laser cladding heads (print heads), this invention uses laser scanning to heat the printed body (workpiece), which can preheat the area where raw material will be deposited, reduce the temperature gradient between the area where raw material is being deposited and other areas of the printed body (workpiece), suppress the generation of thermal cracks, and improve the material properties (mainly mechanical properties) of 3D printed parts. Existing metal 3D printing technologies, especially Selective Laser Melting (SLM) and Direct Energy Deposition (DED) (existing laser-heated coaxial and off-axis filament feeding 3D printing systems, arc-heated off-axis filament feeding 3D printing systems, and laser-heated coaxial powder feeding and off-axis powder feeding 3D printing systems all belong to DED technology), generally suffer from low fatigue resistance of parts, which is also a huge obstacle restricting the application of existing metal 3D printing technology in industrial production.

[0067] (8) Because the existing laser "coaxial wire feeding" heating method is the same as the "heat conduction method" of traditional laser welding (the existing laser coaxial wire feeding metal 3D printing is essentially laser welding), that is, the laser spot power density range is the same as that of traditional heat conduction laser welding. The spot power density value cannot cause significant vaporization of the heated workpiece or raw material, otherwise it will seriously harm the 3D printing process. Therefore, it is impossible to achieve the "laser cleaning" function by increasing the spot power density. However, the present invention uses a scanning heating method, which can quickly disperse heat over a larger area. It can diffuse heat without relying on the "heat conduction" method. Therefore, a higher power density laser beam can be used to simultaneously achieve "laser cleaning" while heating to generate a molten pool. This removes substances harmful to 3D forming (such as oxide film) from the molten pool and the surface of the raw material being deposited. Combined with resistance heating and other methods to generate molten raw material, it can counteract the toxic effects of air on the 3D forming process. Therefore, the present invention can achieve 3D printing in air without the use of protective gas, has lower cost, and can print metal components in open environments. Laser cleaning, also known as laser ablation or photoablation, is a process of removing material from a solid (or sometimes liquid) surface by irradiating it with a laser beam. The surface material is heated and evaporated or sublimated by the absorbed laser energy. Typically, laser cleaning refers to removing a thin layer of material from the surface of an object using a pulsed laser without damaging the underlying structure. In rare cases, continuous laser ablation can be used to remove a thin layer of material from the surface of an object, but due to the extremely high energy of continuous lasers, the thermal effect is very severe, for example, causing remelting of solid metal surfaces, i.e., creating a molten pool (thin molten pool) while ablating the metal. This invention utilizes the characteristic of continuous lasers to generate a molten pool when used as a heat source for laser cleaning.

[0068] In summary, compared with existing coaxial filament feeding laser cladding heads (print heads), the main advantages of this invention are: it enables flexible heating strategies; it allows for printing of finer structures; it avoids overheating of the raw material after deposition, resulting in fewer micropores and higher density within the part material; it has extremely high tolerance for mechanical assembly precision between the optical path and components such as the raw material delivery channel; it creates a stirring effect on the molten pool, improving the performance of the final 3D printed part; it can preheat the area where the raw material is about to be deposited, reducing the temperature gradient between the area where the raw material is being deposited and other areas of the workpiece (printed body), thus suppressing the generation of thermal cracks; it enables 3D printing in air without the use of protective gas, resulting in lower costs; and it allows for printing large metal components in open environments. This invention represents a significant and substantial advancement. Attached Figure Description

[0069] Figure 1 This is a three-dimensional perspective view used to illustrate the compositional principle of a first specific embodiment of a scanning laser printhead according to the present invention;

[0070] Figure 2 yes Figure 1 Front view;

[0071] Figure 3 yes Figure 1 The specific embodiment shown is in operation, in order to Figure 2 Front view perspective;

[0072] Figure 4 This is a schematic diagram for illustration. Figure 1 The laser beam in the specific embodiment shown scans the workpiece;

[0073] Figure 5 This is used to illustrate the compositional principle of a second specific embodiment of a scanning laser printhead according to the present invention;

[0074] Figure 6 This is used to illustrate the compositional principle of a third specific embodiment of a scanning laser printhead according to the present invention;

[0075] Figure 7 This is used to illustrate the compositional principle of a fourth specific embodiment of a scanning laser printhead according to the present invention;

[0076] Figure 8 This is a schematic diagram for illustration. Figure 7 The laser beam in the specific embodiment shown scans the workpiece;

[0077] Figures 9 to 13 This is a schematic diagram illustrating the laser scanning strategy of the present invention.

[0078] The labels are as follows: 1-Raw material conveying channel one, 2-X-axis motor one, 3-X-axis reflector one, 4-Y-axis motor one, 5-Y-axis reflector one, 6-Focusing lens one, 7-X-axis motor two, 8-X-axis reflector two, 9-Y-axis motor two, 10-Y-axis reflector two, 11-Focusing lens two, 12-Laser beam one, 13-Laser beam two, 14-Linear solid material one, 15-Workpiece one, 16-Scanning area of ​​laser beam one, 17-Scanning area of ​​laser beam two, 18-Focusing lens three, 19-Focusing lens four, 20-Focusing lens five, 21-Laser beam three, 22-Laser beam four, 23-Laser beam five, 24-Laser beam six, 25-Linear solid material two, 26-... - Scanning area 3, 27 - Scanning area 4, 28 - Scanning area 5, 29 - Scanning area 6, 37 - Area scanned by laser beam 2, 38 - Area scanned by laser beam 1, 381 - Lower scan density area of ​​the area scanned by laser beam 1, 382 - Higher scan density area of ​​the area scanned by laser beam 1, 39 - Overlapping area between the area scanned by laser beam 1 and the area where raw material is being deposited, 40 - Area where raw material is being deposited, Arrow D1 - Scanning direction 1, Arrow D2 - Scanning direction 2, Arrow D3 - Deposition direction of raw material, Arrow D31 - Direction of raw material deposition trajectory 1, Arrow D32 - Direction of raw material deposition trajectory 2, Arrow D33 - Direction of raw material deposition trajectory 3. Detailed Implementation

[0079] The preferred embodiments of the present invention are listed below, and the present invention will be described in detail with reference to the accompanying drawings.

[0080] In the description of all specific embodiments of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation.

[0081] like Figures 1 to 4 The composition principle of a first specific embodiment of a scanning laser printhead of the present invention shown (excluding non-characteristic structures such as the printhead housing and connecting parts between different components):

[0082] A scanning laser printhead includes a laser interface, a reflector, a focusing lens, and a material delivery channel. A laser beam from the laser interface is modulated by the reflector and focusing lens and projected onto the workpiece from the space surrounding the outlet of the material delivery channel. The material required for printing reaches the workpiece via the material delivery channel; the material can be liquid or solid. Molten material formed by melting the liquid or solid material is deposited on the workpiece. A housing (not shown in the figures) is also provided, within which the laser interface, reflector, and focusing lens are disposed. The material delivery channel passes vertically through the center of the housing.

[0083] The reflector is rotatable to modulate the position of the laser beam projected onto the workpiece, and / or the focusing lens is rotatable and / or movable to modulate the position of the laser beam projected onto the workpiece, thereby causing the laser beam to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited. Specifically, when the laser beam scans and heats the edge of the area on the workpiece where material is being deposited, the laser beam spot moves along the edge of the material being deposited; when the laser beam scans and heats the periphery of the area on the workpiece where material is being deposited, the laser beam spot moves along the periphery of the area on the workpiece where material is being deposited.

[0084] While the laser beam scans and heats the edge and / or periphery of the area on the workpiece where the raw material is being deposited, the laser beam moves relative to the workpiece in the scanned heating zone.

[0085] The reflector is used to change the planar scanning position of the laser spot on the workpiece surface. The focusing lens can be used to change both the planar scanning position of the laser spot on the workpiece surface and to adjust the focus of the laser beam to change the area of ​​the laser spot on the workpiece surface.

[0086] The number of laser beams that can be projected is at least two; each laser beam can be controlled independently; the number of laser beams projected at the same time is controllable;

[0087] The area where the raw material is being deposited refers to the area on the workpiece that is in contact with the raw material being deposited;

[0088] The edge of the area where the raw material is being deposited refers to the edge of the area on the workpiece that is in contact with the raw material being deposited.

[0089] The periphery of the area where the raw material is being deposited refers to the area on the workpiece that is adjacent to or connected to the area where the raw material is being deposited.

[0090] Specifically, the scanning laser printhead mainly consists of a housing (not shown in the attached diagram), a material delivery channel 1, an X-axis motor 2, an X-axis reflector 3, a Y-axis motor 4, a Y-axis reflector 5, a focusing lens 6, an X-axis motor 7, an X-axis reflector 8, a Y-axis motor 9, a Y-axis reflector 10, and a focusing lens 11. It uses linear solid material, i.e., linear solid material 14. X-axis motors 2, 7, 4, and 9 all employ galvanometer motors.

[0091] Specifically: X-axis reflector 3 is connected to the axis of X-axis motor 2 and its rotation angle is controlled by X-axis motor 2; Y-axis reflector 5 is connected to the axis of Y-axis motor 4 and its rotation angle is controlled by Y-axis motor 4; the collimated laser beam 12 is reflected by X-axis reflector 3 and reaches Y-axis reflector 5, then reflected by Y-axis reflector 5 and enters focusing lens 6, and is finally projected onto the upper surface of workpiece 15; the scanning trajectory of laser beam 12 on the upper surface of workpiece 15 is determined by the functional unit composed of X-axis motor 2, X-axis reflector 3, Y-axis motor 4, Y-axis reflector 5 and focusing lens 6;

[0092] X-axis reflector 28 is connected to the axis of X-axis motor 27 and its rotation angle is controlled by X-axis motor 27. Y-axis reflector 210 is connected to the axis of Y-axis motor 29 and its rotation angle is controlled by Y-axis motor 29. After collimation, laser beam 213 is reflected by X-axis reflector 28 and reaches Y-axis reflector 210. Laser beam 213 is reflected by Y-axis reflector 210 and enters focusing lens 211, and is finally projected onto the upper surface of workpiece 15. The scanning trajectory of laser beam 213 on the upper surface of workpiece 15 is determined by the functional unit composed of X-axis motor 27, X-axis reflector 28, Y-axis motor 29, Y-axis reflector 210 and focusing lens 211.

[0093] like Figure 4 As shown: Laser beam 12 moves and scans in the scanning direction D1 indicated by the bidirectional arrow D1. The scanning area on the upper surface of workpiece 15 is the scanning area 16 of laser beam 1. A molten pool is formed in the scanning area 16 of laser beam 1. The scanning area 16 of laser beam 1 is the scanning heating area of ​​laser beam 12 on workpiece 15. Laser beam 13 moves and scans in the scanning direction D2 indicated by the bidirectional arrow D2. The scanning area on the upper surface of workpiece 15 is the scanning area 17 of laser beam 1. The scanning area 17 of laser beam 13 is the scanning heating area of ​​laser beam 13 on workpiece 15. The scanning area 16 of laser beam 1 and the scanning area 17 of laser beam 1 form a circular scanning area and are connected to the projection of the linear solid material 14 on the upper surface of workpiece 15. During the 3D printing process, the scanning heating area moves relative to workpiece 15 together with the scanning laser print head in this specific embodiment (with workpiece 15 as the reference for movement).

[0094] In this embodiment, each reflector rotates in one dimension to move the laser beam in one dimension; of course, in other embodiments, the reflectors can be designed to translate or rotate in two dimensions to move the laser beam in two dimensions.

[0095] In this first specific embodiment, a rotating reflector is used to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited, while the focusing lens remains stationary. Alternatively, in other embodiments, a moving reflector can be used to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited, while the focusing lens remains stationary; alternatively, a rotating focusing lens can be used to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited, while the reflecting lens remains stationary; alternatively, a moving focusing lens can be used to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited, while the reflecting lens remains stationary; or alternatively, in other embodiments, both rotating and moving the reflecting lens and / or the focusing lens can be used to scan and heat the edge and / or periphery of the area on the workpiece where material is being deposited.

[0096] In the first specific embodiment of this invention, during operation, a linear solid material 14 arrives at the upper surface of a workpiece 15 via a material conveying channel 1. The positional relationship between the annular scanning area (scanning area 16 of laser beam one and scanning area 17 of laser beam two) and the projection of the linear solid material 14 onto the upper surface of the workpiece 15 determines whether the linear solid material 14 is heated by the laser. If there is an overlapping area or if the two are connected, then the linear solid material 14 will be heated. However, the degree of heating is determined by the degree of overlap between the two. That is, the laser beam also heats the solid material outside the material conveying channel outlet to generate molten material in the space between the material conveying channel outlet and the workpiece. This specific embodiment is used for metal 3D printing, and the linear solid material 14 is a metal wire.

[0097] In this first specific embodiment, the tip of the linear solid material 14 is melted to generate molten material. The area on the surface of the workpiece 15 that contacts the melted tip of the linear solid material 14 is the area where the material is being deposited. The edge of the area where the material is being deposited refers to the edge of the area on the workpiece that is in contact with the material being deposited, such as... Figure 12 and Figure 13 The overlapping area 39 shown. The periphery of the area where the raw material is being deposited refers to the area on the workpiece adjacent to the area where the raw material is being deposited (e.g., Figure 10 The region 38 scanned by the first laser beam and the region 37 scanned by the second laser beam shown (or the connected region) are shown. Figure 4 The scanning area 16 of laser beam one and the scanning area 17 of laser beam two shown are... Figure 9 The region 37 of the laser beam scanning and the region 38 of the laser beam scanning are shown.

[0098] In this first specific embodiment, the reflector is positioned in front of the focusing lens along the propagation path of the laser beam.

[0099] Of course, in other embodiments, the reflector may be positioned behind the focusing lens in the propagation path of the laser beam.

[0100] In this first specific embodiment, the raw material is solid (i.e., linear solid raw material 14), and the molten raw material formed after the solid raw material is melted is deposited on the workpiece. Of course, in other embodiments, the raw material can also be a liquid raw material.

[0101] In this first specific embodiment, when printing the first layer of a metal part, that is, the first layer of the workpiece, printing is done on a metal substrate. For example, the first layer of a stainless steel part is printed on a stainless steel plate or a metal plate that can be welded to stainless steel.

[0102] like Figure 5 The compositional principle of the second specific embodiment of the scanning laser printhead of the present invention shown (omitting non-characteristic structures such as the printhead housing and connecting parts between different components) is based on... Figures 1 to 4 Based on the first specific embodiment of the scanning laser printhead of the present invention shown, focusing lens 6 and focusing lens 11 are removed, and a ring-shaped focusing lens (i.e., focusing lens 3 18) is used: the center of focusing lens 3 18 is a circular hole for the material delivery channel; both laser beams are focused by focusing lens 3 18.

[0103] like Figure 6 The compositional principle of the third specific embodiment of the scanning laser printhead of the present invention shown (omitting non-characteristic structures such as the printhead housing and connecting parts between different components) is based on... Figures 1 to 4 Based on the first specific embodiment of the scanning laser printhead of the present invention shown, the focusing lens is placed in front of the X-axis reflector, that is: the collimated laser beam passes through the focusing lens 19 and the focusing lens 20 respectively before reaching the corresponding X-axis reflector.

[0104] like Figure 7 and Figure 8 The compositional principle of the fourth specific embodiment of the scanning laser printhead of the present invention shown (omitting non-characteristic structures such as the printhead housing and connecting parts between different components) is based on... Figures 1 to 4Based on the first specific embodiment of the scanning laser printhead of the present invention shown, the number of functional units consisting of an X-axis motor, an X-axis reflector, a Y-axis motor, a Y-axis reflector, and a focusing lens is set to four groups. To avoid interference between the functional units, the positions of two groups of functional units are adjusted upwards. Simultaneously, to accommodate the upward position of the two groups of functional units, the focal length of the focusing lens of the upper functional unit is increased, so that the focal point of the focusing lens of the lower functional unit shares the same horizontal plane. The laser beams projected by the four groups of functional units are: laser beam three 21, laser beam four 22, laser beam five 23, and laser beam six 24.

[0105] like Figure 8 As shown, the scanning areas of laser beams 3 (21), 4 (22), 5 (23), and 6 (24) on the workpiece are respectively: scanning area 3 (26), scanning area 4 (27), scanning area 5 (28), and scanning area 6 (29). Scanning areas 3 (26), 4 (27), 5 (28), and 6 (29) form a ring on the workpiece surface and are connected to the projection of the linear solid material 25 onto the workpiece surface. Of course, the maximum range of the scanning areas of laser beams 3 (21), 4 (22), 5 (23), and 6 (24) on the workpiece covers a 180° radius centered on the projection of the linear solid material 25 onto the workpiece surface; the scanning range can be set.

[0106] When the number of projected laser beams is two or more, the power of each laser beam can be independently controlled; when the number of projected laser beams is two or more, the scanning parameters of each laser beam can be independently controlled. Taking the first specific embodiment of the present invention as an example, parameters such as the shape, area, scanning rate, average power density of the laser spot within the scanning area, dwell time of the laser spot at certain positions during scanning, curve shape of the scanning path, and degree of overlap between the scanning area and the area where the raw material is being deposited are adjusted. Figures 9 to 13 As shown.

[0107] exist Figure 9In the figure, the curved shapes of the scanning paths of laser beam 12 and laser beam 23 are shown by the lines. Arrow D3 indicates the deposition direction of the material on the workpiece surface. The region 40 where the material is being deposited is connected to, but does not overlap with, the regions 38 and 37 scanned by laser beam 1 and laser beam 2, respectively. Both regions are arc-shaped and do not occupy a 180° range. The ring formed by the two regions is not a complete circle and does not fill the 360° area centered on the region 40 where the material is being deposited. The front end of the linear solid material is melted to produce molten material. The area on the workpiece surface that comes into contact with the melted front end of the linear solid material is the region where the material is being deposited. This region is also surrounded (not completely surrounded) by the composite scanning area formed by the regions 38 and 37 scanned by laser beam 1 and laser beam 2, respectively.

[0108] exist Figure 10 In the figure, the curved shapes of the scanning paths of laser beam 12 and laser beam 23 are shown by the lines. Arrow D3 indicates the deposition direction of the material on the workpiece surface. The area 37 scanned by laser beam 2 is discontinuous and square, while the area 38 scanned by laser beam 1 is triangular. The shape formed by the area scanned by laser beam 1 and laser beam 2 is not directly connected to the area 40 where the material is being deposited; they are adjacent and do not completely occupy the 360° perimeter centered on the area where the material is being deposited. The leading edge of the linear solid material is melted to produce molten material. The area on the workpiece surface that comes into contact with the melted leading edge of the linear solid material is the area where the material is being deposited. This area is also surrounded (not completely surrounded) by the composite scanning area formed by the area scanned by laser beam 1 (38) and laser beam 2 (37).

[0109] exist Figure 11In the figure, the curved shapes of the scanning paths of laser beam 12 and laser beam 23 are shown by the lines. Arrow D3 indicates the deposition direction of the raw material on the workpiece surface. The scanning density of the lower scanning density region 381 of the area scanned by laser beam 1 is lower than that of the higher scanning density region 382 of the area scanned by laser beam 1. Under the premise that the power of laser beam 12 remains unchanged, the power densities of the lower scanning density region 381 and the higher scanning density region 382 of the area scanned by laser beam 1 are different, forming a special thermal field. This affects the shape of the molten pool formed by laser beam 12 heating the workpiece 15 (i.e., the printed body 1) and the thermal field of the molten pool, thereby affecting the 3D printing process and the material properties of the final part. The shape formed by the area 37 scanned by laser beam 2, the lower scanning density region 381 of the area scanned by laser beam 1, and the higher scanning density region 382 of the area scanned by laser beam 1 is not directly connected to the area 40 where the raw material is being deposited. The two are adjacent, but they occupy the 360° perimeter of the area 40 where the raw material is being deposited. Laser beam 13 uses lower power, only for heating the surface of the printed object (workpiece) and the newly deposited material. It creates a "heat-preserving effect" in the area 37 scanned by laser beam 13, insufficient to heat and vaporize or partially vaporize the newly deposited material. This achieves a smoother surface while avoiding serious problems such as significant vaporization caused by overheating the newly deposited material with higher power. The leading edge of the linear solid material is melted to produce molten material. The area on the workpiece surface in contact with the melted leading edge of the linear solid material is the area where material is being deposited. This area is also completely surrounded by a composite scanning area consisting of the area scanned by laser beam 13 (37), the lower scanning density area 381 of the area scanned by laser beam 1, and the higher scanning density area 382 of the area scanned by laser beam 1.

[0110] exist Figure 12In the figure, the curved shape of the scanning path of laser beam 12 is shown by the lines in the figure. The area 38 scanned by laser beam 1 is triangular in shape. The scanning laser printhead of the present invention does not generate laser beam 2 13 at the current moment. There is an overlap area between the laser beam scanning area 38 and the material deposition area 40, namely the overlap area 39 between the laser beam scanning area and the material deposition area. The overlap area 39 is the edge of the material being deposited. In other words, by controlling the laser beam to heat the edge of the material being deposited, heat is conducted to the edge of the material deposition area on the printed body through the material being deposited, thereby achieving edge scanning and heating of the material deposition area on the printed body. (Explanation: When the material deposition area is in contact with the material being deposited, the area is covered by the material being deposited. The laser beam cannot directly heat the area covered by the material on the workpiece surface. It needs to heat the material being deposited, and then conduct heat to the material deposition area through the material being deposited. Of course, if the laser beam directly heats the periphery of the material deposition area that is connected to or adjacent to the edge of the material deposition area, the heat in the periphery will also be transferred to the edge of the material deposition area through heat conduction, thereby indirectly heating the edge of the material deposition area.) Laser beam 12 heats the linear solid material 14 through the overlap area 39 between the laser beam scanning area and the material deposition area. The intensity of the heating effect depends mainly on the area of ​​this overlap area. The tip of the linear solid material is melted to produce molten material. The area on the workpiece surface that contacts the melted tip of the linear solid material is the material deposition area, which is also surrounded (semi-enclosed) by the laser beam scanning area 38. When the forward direction of the material deposition path in 3D printing is in the positive direction of the laser beam scanning area 38 (i.e., the direction indicated by arrow D3), the material that has just been deposited will not be reheated by the laser, thus avoiding serious problems caused by overheating. For example, the high fluidity of the material after deposition can lead to reduced shape controllability and molding accuracy. It can also cause significant vaporization, resulting in changes in material composition (different components in an alloy have different boiling points, causing lower-boiling-point components to evaporate more, for example, aluminum in TiAl6V4 titanium alloy evaporates more easily than titanium), and the generation of micropores inside the material (leading to reduced performance of the final part).

[0111] exist Figure 13In the figure, the curved shape of the scanning path of laser beam 12 is shown by the lines. The area 38 scanned by laser beam 1 is distributed along the deposition path of the molten material on the surface of the printed body and includes the area connected to the area 40 where material is being deposited but has not yet been deposited (i.e., the area about to be deposited) and the edge area of ​​the area 40 where material is being deposited. The material deposition trajectory forward direction 1 D31, material deposition trajectory forward direction 2 D32, and material deposition trajectory forward direction 3 D33 represent the forward vectors of the three material deposition paths. The total length of these three material deposition paths is approximately 3.5 times the diameter of the area 38 scanned by laser beam 1. The length can be set in the laser scanning parameters. There is an overlap area between the laser beam scanning area 38 and the material deposition area 40, namely the overlap area 39 between the laser beam scanning area and the material deposition area. The overlap area 39 is the edge of the material being deposited. In other words, by controlling the laser beam to heat the edge of the material being deposited, heat is conducted to the edge of the material deposition area on the printed body through the material being deposited, thereby indirectly scanning and heating the edge of the material deposition area on the printed body. (Explanation: When the material deposition area is in contact with the material being deposited, the area is covered by the material being deposited. The laser beam cannot directly heat the area covered by the material on the workpiece surface. It needs to heat the material being deposited, and then conduct heat to the material deposition area through the material being deposited. Of course, if the laser beam directly heats the periphery of the material deposition area that is connected to or adjacent to the edge of the material deposition area, the heat from the periphery will also be transferred to the edge of the material deposition area through heat conduction, thus indirectly heating the edge of the material deposition area.) The leading edge of the linear solid material is melted to create molten material that is being deposited. The area on the surface of the printed body that comes into contact with the melted leading edge of the linear solid material is the area where the material is being deposited. This area is surrounded (180° enclosed / semi-enclosed) by the area 38 scanned by the laser beam. The overlapping area 39 is actually occupied by the molten material being deposited. The heating effect of the laser beam in this overlapping area is conducted to the overlapping area by heating the molten material being deposited, which is indirect heating. This scanning pattern of the area 38 scanned by the laser beam can preheat the area where the material will be deposited, reduce the temperature gradient between the area where the material is being deposited and other areas of the printed body, suppress the generation of thermal cracks, and improve the material properties of the 3D printed parts (mainly mechanical properties, such as the fatigue resistance of metal parts).Existing metal 3D printing technologies, especially Selective Laser Melting (SLM) and Direct Energy Deposition (DED) (existing coaxial and off-axis 3D printing systems based on laser heating, off-axis 3D printing systems based on electric arc heating, and coaxial and off-axis powder feeding 3D printing systems based on laser heating also belong to DED technology), generally suffer from low fatigue resistance of parts, which is a huge obstacle restricting the application of existing metal 3D printing technologies in industrial production.

[0112] visible, Figure 9 The laser beam is used to scan and heat the periphery of the area on the printed body where the material is being deposited. Specifically, the laser beam scans and heats the area on the printed body that is connected to the area where the material is being deposited. Figure 10 and Figure 11 The laser beam is used to scan and heat the periphery of the area on the printed body where the material is being deposited. Specifically, the laser beam scans and heats the area on the printed body adjacent to the area where the material is being deposited. Figure 12 and Figure 13 The laser beam scans and heats both the edges and periphery of the area on the printed body where material is being deposited. Of course, in other scanning and heating methods, only the edges of the area on the printed body where material is being deposited (i.e., the area indicated by reference numeral 39) can be scanned and heated.

[0113] like Figures 9 to 13 The scanning heating method shown in the figure involves a laser scanning and heating the surface of the printed object to generate a molten pool. The "scanning heating" method can have a "stirring" effect on the molten pool, which can have a beneficial effect on the performance of the final 3D printed part, such as reducing micropores.

[0114] Other preferred embodiments of the invention are also available. For example, a collimating lens is provided to convert a non-parallel laser beam into a parallel laser beam, such as converting diverging laser light from a fiber laser into parallel light. The collimating lens is located before the laser interface in the propagation path of the laser beam.

[0115] For example, a beam splitter is used to split a laser beam into at least two beams, allowing a single laser to generate multiple laser beams. The beam splitter is positioned in the propagation path of the laser beams, before the laser interface.

[0116] For example, a window mirror is installed to prevent external substances from contacting the reflector and focusing lens at the laser emission port. The window mirror is a type of protective mirror.

[0117] For example, a gas passage is provided for spraying gas to form an air curtain to prevent or reduce external contamination of the reflector, focusing lens and window lens, and a passage for spraying inert gas is provided, for example, a vent is provided around the lower end outlet of the raw material conveying channel to spray protective gas onto the molten raw material and the molten pool on the workpiece to form a protective atmosphere (for example, argon gas is sprayed onto the space where the molten raw material and the molten pool are located to form an inert gas protective atmosphere).

[0118] For example, a liquid cooling path can be set up to cool the scanning laser printhead (housing, motor, and optical components, etc.).

[0119] For example, setting up an optical path switching component to switch the laser beam from one laser interface to another (for example, using a motor to drive a reflector to control the propagation path of the laser and achieve "time-division multiplexing").

[0120] For example, the focusing lens is adjustable, and the focusing method can be manual focusing, electric focusing, pneumatic focusing, or hydraulic focusing. When electric focusing is used, three-dimensional scanning heating can be achieved (see the description above for details).

[0121] For example: a laser interface connects to the laser output head of a laser (e.g., a QBH interface for connecting to the laser output head of a fiber laser).

[0122] For example, at least two laser beams are projected. One portion of the laser beam scans and heats the edge and / or periphery of the area on the workpiece where the raw material is being deposited to create a molten pool. The other portion of the laser beam modifies the shape of the already printed surface of the workpiece, such as laser cutting, laser engraving, or laser cleaning (e.g., cleaning oxide film) of areas of the workpiece that are not currently deposited with raw material, in order to obtain better surface quality and adjust the structure of certain areas of the workpiece (e.g., modifying the wall thickness).

[0123] For example, the reflector and / or focusing lens control the laser beam to scan and heat the periphery of the area where the raw material is being deposited on the printed body (workpiece), and its scanning parameters can be dynamically adjusted. Throughout the printing process of a part, the laser scanning heating parameters are not fixed. When printing different areas of a part, parameters such as the width of the scanning area, the degree of overlap between the scanning area and the area where the raw material is being deposited on the printed body, the scanning line density within the scanning area, and the power can be adjusted as needed. For instance, when printing a part, it needs to be built on a base plate (support plate) because the first layer is tightly connected to the base plate, providing good heat dissipation. Printing the first layer requires the maximum heating power and a large scanning range. As the printing height increases, the heat dissipation conditions worsen, and the scanning parameters also need to be adjusted. Similarly, when printing thin-walled structures, the scanning range and heating power are smaller than for thick-walled structures. Furthermore, the scanning parameters required for printing edge structures with sharp corners are different from those required for printing structures in non-edge locations.

[0124] For example, the reflector and / or focusing lens control the laser beam to heat the material being deposited while simultaneously scanning and heating the edge and / or periphery of the area where the material is being deposited.

[0125] Because the existing laser "coaxial wire feeding" heating method is the same as the "heat conduction method" of laser welding (the existing laser coaxial wire feeding metal 3D printing is essentially based on laser welding), that is, the laser spot power density range is the same as that of traditional heat conduction laser welding. The spot power density value cannot produce significant vaporization, otherwise it will seriously damage the 3D printing process. Therefore, it is impossible to increase the spot power density to achieve the "laser cleaning" function. However, the present invention uses a scanning heating method, which can rapidly disperse heat over a larger area. It can diffuse heat without relying on the "heat conduction" method. Therefore, a higher power density laser beam can be used to simultaneously achieve "laser cleaning" while heating the workpiece to generate a molten pool. This removes substances harmful to 3D forming (such as removing oxide films) from the surface of the molten pool and the molten material. Combined with resistance heating and other methods to generate molten material, it can counteract the toxic effects of air on the 3D forming process. Preferably, the laser beam can be used to scan and heat the interface between the workpiece surface and the material being deposited to perform laser cleaning on the interface. Therefore, the present invention can achieve 3D printing in air without the use of a protective gas. Laser ablation, also known as laser erosion or photoablation, is a process that removes material from a solid (or sometimes liquid) surface by irradiating it with a laser beam. The surface material is heated and evaporated or sublimated by the absorbed laser energy. Typically, laser cleaning refers to removing a thin layer of material from the surface of an object using a pulsed laser without damaging the underlying structure. In rare cases, continuous laser ablation can also be used to remove thin layers of material from the surface of an object, but due to the extremely high energy of continuous lasers, the thermal effects are very severe, for example, causing remelting of solid metal surfaces, i.e., creating a molten pool (thin molten pool) while ablating the metal. This invention utilizes the characteristic of continuous lasers to generate a molten pool when used as a heat source for laser cleaning.

[0126] The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent transformations and modifications made based on the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A scanning laser head, characterized in that: a laser interface, a mirror, a focusing lens and a feed channel are provided, a laser beam from the laser interface is modulated by the mirror and the focusing lens, and is projected from the surrounding space of the feed channel to a workpiece; a feed channel is provided for the feed of a printing material to the workpiece, the printing material is in a liquid or solid state, and the liquid or solid material is melted to form a molten material which is deposited on the workpiece; the mirror is rotatable and / or movable to modulate the position of the laser beam projected on the workpiece, wherein the mirror is two-dimensionally movable or rotatable to move the laser beam in two dimensions; and / or the focusing lens is rotatable and / or movable to modulate the position of the laser beam projected on the workpiece, wherein the focusing lens is two-dimensionally movable or rotatable to move the laser beam in two dimensions, or the focusing lens is three-dimensionally movable or rotatable to move the laser beam in two dimensions and to focus the focusing lens, so that the laser beam scans and heats the edge and / or periphery of the area of the workpiece where the material is being deposited; while the laser beam scans and heats the edge and / or periphery of the area of the workpiece where the material is being deposited, the scanning area of the laser beam on the workpiece moves relative to the workpiece; the number of laser beams that can be projected is at least two; each laser beam can be independently controlled; the number of laser beams projected at the same time is controllable; the area of the material being deposited refers to the area of the workpiece in contact with the material being deposited; the edge of the area of the material being deposited refers to the edge of the area of the workpiece in contact with the material being deposited; and the periphery of the area of the material being deposited refers to the area of the workpiece adjacent or connected to the area of the material being deposited.

2. The scanning laser head according to claim 1, characterized in that: when the material is in a solid state, the laser beam also heats the solid material outside the outlet of the feed channel to generate a molten material in the space between the outlet of the feed channel and the workpiece.

3. The scanning laser head according to claim 1, characterized in that: when the number of laser beams projected on the workpiece at the same time is two or more than two, the scanning areas of the laser beams projected on the workpiece can form a composite scanning area, and the composite scanning area can surround the area of the workpiece where the material is being deposited.

4. The scanning laser head according to claim 1, characterized in that: the laser beam scans and heats the edge and / or periphery of the area of the workpiece where the material is being deposited to generate a molten pool; when the number of laser beams projected is two or more than two, the power of each laser beam can be independently controlled; and when the number of laser beams projected is two or more than two, the scanning parameters of each laser beam can be independently controlled.

5. The scanning laser head according to claim 1, characterized in that: the number of mirrors is at least two. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The number of focusing mirrors is at least two, and the number of focusing mirrors is the same as the number of laser beams, each laser beam corresponding to one focusing mirror; or the number of focusing mirrors is one, and each laser beam passes through the focusing mirror.

6. The scanning laser head according to claim 1, wherein: The focusing mirror is a field lens focusing mirror or a non-field lens focusing mirror. The mirror is driven by electromagnetic force, piezoelectric element, thermal deformation, magnetic deformation, electrostriction or fluid.

7. The scanning laser head according to claim 1, wherein: The mirror is located before or after the focusing mirror in the propagation path of the laser beam.

8. The scanning laser head according to claim 1, wherein: A collimating mirror is provided to convert the non-parallel laser beam into a parallel laser beam, and the collimating mirror is located before the laser interface in the propagation path of the laser beam; A beam splitter is provided to split one laser beam into at least two laser beams, and the beam splitter is located before the laser interface in the propagation path of the laser beam; A window mirror is provided to block external substances from contacting the mirror and the focusing mirror at the laser exit port; A gas passage is provided to inject gas to form a gas curtain to prevent or reduce the pollution of external substances to the mirror, the focusing mirror and the window mirror, and / or to inject protective gas to form a protective atmosphere on the molten pool of the molten raw material and the workpiece; A liquid cooling passage is provided to cool the scanning laser head; An optical path switching assembly is provided to switch the laser beam from one laser interface to another laser interface.

9. The scanning laser head according to claim 1, wherein: The focusing mirror is adjustable, and the focusing adjustment mode is manual focusing, electric focusing, pneumatic focusing or hydraulic focusing.

10. The scanning laser head according to claim 1, wherein: The laser interface is connected to the laser output head of a laser.

11. The scanning laser head according to claim 1, wherein: The area on the raw material deposition path of the workpiece to be scanned and heated by the laser beam can be preheated before being scanned and heated by the laser beam, and the preheating range can be set.

12. The scanning laser head according to claim 1, wherein: The mirror and / or the focusing mirror control the laser beam to heat the edge of the raw material being deposited, so as to conduct heat to the edge of the area of the raw material being deposited on the workpiece through the raw material being deposited, thereby achieving scanning and heating of the edge of the area of the raw material being deposited on the workpiece.

13. The scanning laser head according to claim 1, wherein: The number of projected laser beams is at least two, wherein a part of the laser beams scan and heat the edge and / or periphery of the area of the raw material being deposited on the workpiece to generate a molten pool, and the other part of the laser beams modify the shape of the already printed workpiece surface on the workpiece.

14. The scanning laser print head of claim 1 wherein: the mirrors and / or focusing mirrors control the heating of the material being deposited while simultaneously scanning the heating of the edges and / or periphery of the area where the material is being deposited.

15. The scanning laser print head of claim 1 wherein: the laser beam scans the interface between the surface of the workpiece and the material being deposited to laser clean the interface.

Images