Aluminum alloy coaxial wire feeding laser additive manufacturing method and system

Abstract

The application discloses an aluminum alloy coaxial wire feeding laser additive manufacturing method and system, and the method comprises the following steps: placing an aluminum alloy substrate to be processed on a jig, adjusting a laser processing head to make a light wire concentric, so that a laser beam emitted by a single light source can melt an aluminum wire and form a molten pool, the laser beam is a ring-shaped beam; setting process parameters and planning a processing path, and setting a Z-direction moving height of each layer; controlling the jig to move according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until the additive manufacturing is completed. The application can realize accurate coupling of light and wire, avoid scanning unidirectionality, light-wire interference, aluminum wire spheroidization and other problems by constructing a single-light-source light-in-wire coaxial wire feeding system for laser additive manufacturing of aluminum alloy.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and specifically to a method and system for coaxial wire feeding laser additive manufacturing of aluminum alloys. Background Technology

[0002] Aluminum alloys are characterized by low density, high strength, and good plasticity, along with excellent electrical and thermal conductivity and corrosion resistance. They are among the most widely used non-ferrous metal structural materials in industry, with extensive applications in aerospace, 3C (computers, communications, and consumer electronics), and chemical industries. As the application of aluminum alloys in industrial production becomes increasingly widespread, research on additive manufacturing of aluminum alloys has also attracted considerable attention.

[0003] Laser additive manufacturing with wire feeding offers advantages such as high material utilization, low environmental pollution, low material cost, and minimal impact from spatial conditions, making it a promising area for development. However, the "outward-facing wire feeding" laser additive manufacturing method suffers from drawbacks such as poor wire coupling accuracy and unidirectional scanning. The "multi-source, inward-facing coaxial wire feeding" laser additive manufacturing method, composed of multiple laser sources, suffers from problems such as a large space requirement for the forming system and high operating and maintenance costs. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides a method and system for coaxial wire feeding laser additive manufacturing of aluminum alloy. By constructing a single-source coaxial wire feeding system for laser additive manufacturing of aluminum alloy, precise coupling of light and wire can be achieved, avoiding problems such as scanning unidirectionality, light-wire interference, and aluminum wire spheroidization.

[0005] According to one aspect of the present invention, a method for coaxial wire feeding laser additive manufacturing of aluminum alloy is provided, comprising: The aluminum alloy substrate to be processed is placed on the fixture, and the laser processing head is adjusted to make the filament concentric so that the laser beam emitted from a single light source can melt the aluminum wire and form a molten pool. The laser beam is a ring beam. Set the process parameters and plan the processing path, as well as set the movement height of each layer in the Z direction; The control fixture moves according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until additive manufacturing is completed.

[0006] As a further technical solution, when adjusting the laser processing head to make the filament concentric, it also includes: adjusting the laser processing head to make the spot energy uniform.

[0007] As a further technical solution, the process parameters include laser power, wire feeding speed, scanning speed, and defocusing amount. The laser power is adjustable within the range of 2400-2600W, the wire feeding speed is adjustable within the range of 1600-1900mm / min, the scanning speed is adjustable within the range of 40-60mm / s, and the defocusing amount is adjustable within the range of 5-6mm.

[0008] As a further technical solution, when it is necessary to reduce the width, height and depth of the cladding layer, the laser power and wire feeding speed are kept constant, while the scanning speed is increased.

[0009] As a further technical solution, when it is necessary to increase the width of the cladding layer or decrease the height and depth of the cladding layer, the scanning speed and wire feeding speed should be kept constant, while the laser power should be increased.

[0010] As a further technical solution, when it is necessary to increase the height of the cladding layer, reduce the depth of the cladding layer, and allow the width of the cladding layer to fluctuate within a certain range, the laser power and scanning speed should be kept constant, while the wire feeding speed should be increased.

[0011] As a further technical solution, the Z-axis layer movement height is set, including: performing single-pass single-layer additive manufacturing, measuring the first layer forming height with vernier calipers, and setting this first layer forming height as the Z-axis layer movement height of additive manufacturing.

[0012] As a further technical solution, before setting the moving height of each layer in the Z direction, the following steps are also included: turning on the protective gas and adjusting the protective gas flow rate.

[0013] According to one aspect of the present invention, an aluminum alloy coaxial wire feeding laser additive manufacturing system is provided, comprising: a laser source, a laser processing head, a wire feeding device, a fixture, and a control device. The laser source is a single source and provides a laser beam to the laser processing head. The laser processing head shapes the laser beam into a ring beam, which is concentrically arranged with the aluminum wire provided by the wire feeding device to melt the aluminum wire and form a molten pool. The fixture is used to place an aluminum alloy substrate. The control device is used to set process parameters and plan a processing path, and to control the fixture to move according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until additive manufacturing is completed.

[0014] As a further technical solution, the wire feeding device is also equipped with a straightener to keep the aluminum wire concentric with the annular beam.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention constructs a single-source coaxial wire feeding system and achieves additive manufacturing of aluminum alloy wire by adjusting four major process parameters: laser power, wire feeding speed, scanning speed, and defocusing amount. The additive manufacturing part has good performance as verified by microhardness. It solves the problems of low efficiency, high cost, low density and many defects in powder laser additive manufacturing, and solves the defects of poor optical-wire coupling accuracy and single scanning direction in the optical outward wire feeding laser additive manufacturing method.

[0016] 2. This invention uses aluminum alloy wire as the raw material for additive manufacturing. Compared with powder laser additive manufacturing, it has higher material utilization, lower cost, higher density of cladding layer, and fewer defects.

[0017] 3. This invention shapes Gaussian light into ring light using a laser processing head, making full use of the laser beam's energy. This allows a single-source laser beam to melt cold aluminum wire without the need for a composite light source. Furthermore, the ring light reduces the temperature and depth of the molten pool to a certain extent, which reduces substrate deformation and prevents overheating of the molten pool and the previous deposited layer. This can improve the microstructure and performance of the deposited layer. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a laser additive manufacturing method for coaxial wire feeding of aluminum alloy provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of a laser additive manufacturing apparatus provided in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram showing the shape and size of the light spot at the processing height, provided for an embodiment of the present invention.

[0022] Figure 4 A schematic diagram of a machined part produced by the method provided in an embodiment of the present invention.

[0023] Figure 5 Metallographic images of additively manufactured parts after cutting, polishing, and etching, provided in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram of the microhardness test results provided in an embodiment of the present invention.

[0025] Figure 7This is a schematic diagram of the geometric features of the cladding layer corresponding to different scanning speeds provided in an embodiment of the present invention.

[0026] Figure 8 This is a schematic diagram of the geometric features of the cladding layer corresponding to different laser powers, provided in an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the geometric features of the cladding layer corresponding to different wire feeding speeds provided in an embodiment of the present invention. Detailed Implementation

[0028] In laser additive manufacturing, aluminum alloys exhibit low laser absorption during the forming process, leading to severe spheroidization and unsatisfactory forming results. To address this, this invention employs a single-source coaxial wire feeding laser additive manufacturing method. The Gaussian beam is shaped into a ring beam using a laser processing head, constructing a "single-source coaxial wire feeding" laser additive manufacturing system. This system allows for precise coupling of light and wire, avoiding problems such as unidirectional scanning, light-wire interference, and aluminum wire spheroidization.

[0029] Based on the constructed "single-source coaxial wire feeding" laser additive manufacturing system, this invention, by determining a suitable process window, prepares high-integrity, high-performance shaped part samples, realizing the laser additive manufacturing of aluminum alloys using a single-source coaxial wire feeding system.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0031] This invention provides a method for coaxial wire feeding laser additive manufacturing of aluminum alloys, such as... Figure 1As shown, the process includes: placing the aluminum alloy substrate to be processed on a fixture; adjusting the laser processing head to make the filament concentric so that the laser beam emitted from a single light source can melt the aluminum wire and form a molten pool, wherein the laser beam is a ring beam; setting process parameters and planning the processing path, and setting the moving height of each layer in the Z direction; controlling the fixture to move according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until additive manufacturing is completed.

[0032] It should be noted that, considering that the absorption rate of aluminum alloy to laser is only 10% at room temperature, and that the absorption rate will increase to 40%-60% as the temperature of aluminum alloy increases, especially after the material melts, this invention uses a ring beam for additive manufacturing. The ring beam is used to heat the aluminum wire as a whole, reducing the temperature gradient and increasing its absorption capacity at the laser wavelength.

[0033] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this invention involves devices including a laser, a laser processing head, a fixture, an air blowing device, and a wire feeding device, etc. Figure 2 As shown, the adjustable process parameters include laser power, wire feed speed, scanning speed, and defocusing amount. In the implementation of the method described in this embodiment, an aluminum substrate is placed on a fixture. Appropriate process parameters are given by a computer, and a laser beam is used to melt the aluminum wire and form a molten pool. The scanning path is input to control the movement of the fixture platform, causing relative movement between the aluminum wire and the substrate. The aluminum wire, melted by the laser beam, is deposited layer by layer along the scanning path until additive manufacturing is completed. The final deposited layer is uniform and smooth.

[0034] The aluminum alloy substrate used in this embodiment of the invention is grade 7075, with a thickness of 3 mm. The aluminum wire used is grade 7075, with a diameter of 1.2 mm. The laser used to complete the aluminum wire additive manufacturing has a wavelength of 1064 nm, a power of 3000 W, and a core diameter of 600 μm.

[0035] In this embodiment of the invention, a Pretzker coaxial wire feeding welding head is used to construct a single-source light source internal coaxial wire feeding system, thereby forming the additive manufacturing method described above.

[0036] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this embodiment of the invention further includes: pre-treating the aluminum alloy substrate. Specifically, the substrate surface is wiped with alcohol to ensure it is free of dirt, and then fixed onto a fixture.

[0037] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this invention embodiment further includes: equipment startup inspection to ensure wire concentricity and uniform spot energy. Wire concentricity and spot energy uniformity can both be adjusted by the laser processing head, and spot energy uniformity can be measured by a spot energy analyzer.

[0038] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this invention embodiment further includes setting process parameters: laser power, wire feeding speed, scanning speed, and defocusing amount. Specifically, the laser power can be selected within the range of 2400-2600W, the wire feeding speed can be selected within the range of 1600-1900mm / min, the scanning speed can be selected within the range of 40-60mm / s, and the focal point position can be selected within the range of 5-6mm of negative defocus. In addition, the outer ring diameter of the annular spot emitted from the laser processing head ranges from 2.4-2.6mm.

[0039] This invention analyzes the effects of laser power, wire feed speed, and scanning speed on additive manufacturing, determines a suitable process window for laser additive manufacturing of aluminum alloys, and can produce high-integrity, high-performance shaped part samples.

[0040] Table 1 Laser cladding process parameters at different scanning speeds

[0041] See Table 1 and Figure 7 Table 1 shows the laser cladding process parameters at different scanning speeds. Figure 7 The graph shows the geometric characteristics of the cladding layer at different scanning speeds. As can be seen from the graph, the width, height, and depth of the cladding layer gradually decrease as the scanning speed increases. This is because, under a certain laser power, as the scanning speed increases, the linear energy (the energy input per unit length of the cladding channel) decreases, resulting in less molten metal and thus a decrease in the width, height, and depth of the cladding layer.

[0042] Table 2 Laser Cladding Process Parameters under Different Laser Powers

[0043] See Table 2 and Figure 8 Table 2 shows the laser cladding process parameters under different laser powers. Figure 8The graph shows the geometric characteristics of the cladding layer for different laser powers. As can be seen from the graph, the width of the cladding layer gradually increases while the height gradually decreases with increasing laser power. This is because the actual laser cladding energy is mainly determined by the scanning speed and laser power. With other process parameters remaining constant, increasing the laser power or decreasing the scanning speed can increase the laser radiation energy received by the cladding layer. Increased energy leads to more efficient convection in the molten pool, and the width of the cladding layer also increases accordingly. When the laser power is 2800W, the entire cladding layer cross-section is flat; when the laser power is less than 2200W, the laser energy is insufficient to completely melt the aluminum wire, making it difficult to continue the cladding process and ultimately causing wire jamming.

[0044] Table 3 Laser cladding process parameters at different wire feed speeds

[0045] See Table 3 and Figure 9 Table 3 shows the laser cladding process parameters at different wire feed speeds. Figure 9 The graph shows the geometric characteristics of the cladding layer at different wire feed speeds. As the wire feed speed increases, the width of the cladding layer fluctuates between 2.5 mm and 2.7 mm, indicating that the width is mainly determined by the spot diameter and is less affected by the wire feed speed. The height of the cladding layer gradually increases because as the wire feed speed increases, the mass of the cladding layer per unit time also increases. The slow change in the width of the cladding layer inevitably leads to an increase in its height.

[0046] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this invention further includes planning a processing path and controlling the movement path via coordinates. By controlling the fixture to move according to the planned processing path, relative movement between the aluminum wire and the aluminum alloy substrate is caused, thereby allowing the aluminum wire, melted by the laser beam, to be deposited layer by layer along the scanning path until additive manufacturing is completed.

[0047] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this embodiment of the invention further includes connecting a protective gas and adjusting the protective gas flow rate. Specifically, the protective gas used is argon, and the flow rate is 5-10 L / min.

[0048] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this embodiment of the invention further includes setting the moving height of each layer in the Z direction: performing single-pass single-layer additive manufacturing, measuring the forming height of the first layer with a vernier caliper, and setting this height as the moving height of each layer in the Z direction of additive manufacturing.

[0049] The laser additive manufacturing method for aluminum alloys using a single-source coaxial wire feeding system provided in this embodiment of the invention involves setting the moving height of each layer in the Z direction, and then performing additive manufacturing layer by layer according to the set moving height until all layers are completed.

[0050] Based on the same inventive concept as the method embodiments, this embodiment of the invention also provides an aluminum alloy coaxial wire feeding laser additive manufacturing system, such as... Figure 2 As shown, the system includes: a laser source, a laser processing head, a wire feeding device, a fixture, and a control device. The laser source is a single source and provides a laser beam to the laser processing head. The laser processing head shapes the laser beam into a ring beam, which is concentrically positioned with the aluminum wire provided by the wire feeding device to melt the aluminum wire and form a molten pool. The fixture is used to place the aluminum alloy substrate. The control device (not shown) is used to set process parameters and plan the processing path, and to control the fixture to move according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until additive manufacturing is completed.

[0051] As a preferred embodiment, the present invention utilizes Figure 2 Additive manufacturing was performed using a coaxial wire-feeding laser additive manufacturing system for aluminum alloy. First, a 3mm thick 7075 aluminum alloy substrate was pre-treated by wiping its surface with alcohol to ensure it was free of contaminants. Then, it was fixed onto the fixture worktable. The equipment was started, and the concentricity of the filament and the uniformity of the laser spot energy were checked. The laser processing head was adjusted to ensure filament concentricity and uniform spot energy. The uniformity of the spot energy was measured using a spot energy analyzer. The spot shape and size at the processing height are shown in the attached figure. Figure 3 As shown, the outer ring diameter of the light spot is 2.4-2.6 mm, and the energy error value is <2.9%.

[0052] Setting process parameters: Set the laser power to 2600W, wire feed speed to 1900mm / min, scanning speed to 60mm / s, and adjust the focal position to negative defocus of 5mm. Plan the processing path according to requirements; in this embodiment, the path is a 150mm*70mm rectangle with a corner radius of 7.5mm. Connect the side-blowing protective gas pipe to argon gas and adjust the protective gas flow rate to 7L / min. Setting the Z-direction layer-by-layer movement height: Perform single-pass, single-layer additive manufacturing, measure the first layer's forming height with calipers, and set this height as the Z-direction layer-by-layer movement height for additive manufacturing. Perform additive manufacturing layer by layer until the additive manufacturing is complete. Using the method of this embodiment, the forming efficiency of aluminum alloy wire additive manufacturing structural parts is greatly improved, the forming process is stable, the forming effect is good with no oxidation, and multi-directional additive manufacturing can be achieved. The forming results are shown in the attached figure. Figure 4 As shown in the attached figure. The metallographic structure of the formed part was observed under a microscope after cutting, polishing, and etching. Figure 5As shown in the figure; and the microhardness of the base material and the additively manufactured part was tested using a microhardness tester, and the test results are attached. Figure 6 As shown.

[0053] In summary, the aluminum alloy coaxial wire feeding laser additive manufacturing method provided by this invention achieves additive manufacturing of aluminum alloy wire by adjusting four major process parameters: laser power, wire feeding speed, scanning speed, and defocusing amount. The additive manufacturing part has good performance as verified by microhardness testing. The method provided by this invention can solve the problems of low efficiency, high cost, low density of cladding layer, and many defects in powder laser additive manufacturing. At the same time, it solves the defects of poor optical-wire coupling accuracy and single scanning directionality in the optically outward wire feeding laser additive manufacturing method.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for coaxial wire feeding laser additive manufacturing of aluminum alloy, characterized in that, include: The aluminum alloy substrate to be processed is placed on a fixture, and the laser processing head is adjusted to make the laser filament concentric so that the laser beam emitted from a single light source can melt the aluminum wire and form a molten pool. The laser beam is a ring beam, and the outer ring diameter of the ring beam at the processing height is 2.4-2.6 mm. The aluminum alloy substrate is 7075 aluminum alloy, and the aluminum wire is 7075 aluminum wire. The process parameters are set and the processing path is planned, as well as the moving height of each layer in the Z direction is set; the process parameters include laser power, wire feeding speed, scanning speed and defocusing amount, and the laser power is adjustable within 2400-2600W, the wire feeding speed is adjustable within 1600-1900mm / min, the scanning speed is adjustable within 40-60mm / s, and the defocusing amount is adjustable within 5-6mm; The control fixture moves according to the planned processing path, causing relative movement between the aluminum wire and the aluminum alloy substrate, so that the aluminum wire melted by the laser beam is deposited layer by layer on the scanning path until additive manufacturing is completed.

2. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, Adjusting the laser processing head to make the filament concentric also includes: adjusting the laser processing head to make the spot energy uniform.

3. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, When it is necessary to reduce the width, height and depth of the cladding layer, keep the laser power and wire feeding speed constant, and increase the scanning speed.

4. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, When it is necessary to increase the width of the cladding layer or decrease its height, keep the scanning speed and wire feeding speed constant and increase the laser power.

5. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, When it is necessary to increase the height of the cladding layer, decrease the depth of the cladding layer, and allow the width of the cladding layer to fluctuate within a certain range, keep the laser power and scanning speed constant, and increase the wire feeding speed.

6. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, Setting the Z-axis layer movement height includes: performing single-pass single-layer additive manufacturing, measuring the first layer forming height with vernier calipers, and setting this first layer forming height as the Z-axis layer movement height for additive manufacturing.

7. The method for coaxial wire feeding laser additive manufacturing of aluminum alloy according to claim 1, characterized in that, Before setting the Z-direction movement height for each layer, the process also includes: turning on the protective gas and adjusting the protective gas flow rate.

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