Method for blue light wire feeding additive manufacturing of copper or copper alloy

Abstract

A method for additively manufacturing copper or copper alloys by blue light wire feeding, wherein the blue light is composed of light beams emitted by multiple independently controlled blue light lasers, and the power of the blue light is 1200-5000W; the method is coaxial blue light laser wire feeding, that is, the blue light is used to melt and deposit coaxial copper or copper alloy wires onto a substrate to form a copper or copper alloy print; the blue light is evenly distributed as a heat source. The process control of the invention is simple, the process is stable, and the copper or copper alloy material manufactured by additive manufacturing has high mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of laser additive manufacturing, and in particular to a method for blue light wire feeding additive manufacturing of copper or copper alloy. Background Art

[0002] Additive manufacturing (3D printing) is a bottom-up, layer-by-layer manufacturing technology. Laser additive manufacturing technology includes laser powder laying, laser powder feeding, laser wire feeding, etc., depending on the process and cladding materials. Depending on the laser band used, it can include infrared laser manufacturing, blue laser manufacturing and composite light source manufacturing.

[0003] Copper and its alloys have been recognized and paid attention to by the industry due to their excellent thermal conductivity, electrical conductivity, ductility and corrosion resistance. They have important applications in electronic information, aerospace, new energy vehicles and other fields.

[0004] In order to manufacture copper or copper alloy products, existing technologies such as CN114131049B provide an additive manufacturing method for copper and copper alloys, which uses blue light and infrared light as heat sources to melt copper or copper alloy powder materials for laser powder feeding additive manufacturing. Using blue light laser to melt copper or copper alloys has outstanding advantages: (1) copper or copper alloys have a high absorption rate of blue light; (2) the surface quality of copper or copper alloys, such as oil stains, oxidation and rust, has no effect on the efficiency and quality of blue light cladding. Therefore, the process of using blue light laser to melt copper or copper alloy materials is stable and can achieve fast and high-quality cladding.

[0005] However, the existing technology still has problems: (1) Using a single laser beam as a heat source, the blue light power is 800-1000W, which cannot achieve high-power melting manufacturing, let alone high deposition rate; (2) Using 3000-5000W infrared light as an auxiliary heat source to melt copper or copper alloy materials complicates the additive manufacturing control process. In addition, the infrared light power is 3-5 times that of blue light. Solid copper has a low absorption rate for infrared light, while liquid copper has a high absorption rate for infrared light. In the melting process of copper or copper alloy powder, micro-particles are prone to occur. (3) Copper or copper alloy has a high reflectivity to infrared light. Its absorption rate of 3000-5000W infrared light is only about 20%. 80% of the infrared light is reflected, which can easily cause damage to optical devices and reduce the service life of equipment. (4) The powder feeding method of the powder feeder makes it difficult to accurately control the delivery and deposition amount of powder material, and the deposition rate of the powder feeding is low and the cost is high. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method for blue light wire feeding additive manufacturing of copper or copper alloy.

[0007] A method for additively manufacturing copper or copper alloys using blue light wire feeding, wherein the blue light is composed of light beams emitted by multiple independently controlled blue light lasers; the method is coaxial blue light laser wire feeding, that is, the blue light is used to melt and deposit coaxial copper or copper alloy wires onto a substrate to form a copper or copper alloy print; the blue light presents a uniform heat source distribution.

[0008] Further steps include:

[0009] Step 1: Select copper or copper alloy wire and determine its diameter;

[0010] Step 2: Turn on multiple independently controlled blue lasers to achieve the laser target power output;

[0011] Step 3: The wire feeding system feeds the wire, and the laser melts the copper or copper alloy wire to form a molten pool that is deposited on the substrate to form a weld. The weld goes from line to surface to body, and finally forms a copper or copper alloy print.

[0012] Furthermore, the target power is 1200-5000W, and the diameter of the wire is 0.6-2mm.

[0013] Furthermore, the target power is 1200-3000W, and the diameter of the wire is 0.6-1.2mm.

[0014] Furthermore, the plurality of independently controlled blue lasers are arranged annularly and symmetrically around the wire.

[0015] Furthermore, the spot shape formed by the light beams emitted by the multiple independently controlled blue lasers is crescent-shaped, circular or elliptical, and the spot shape of the blue light is circular, ring-shaped or petal-shaped.

[0016] Furthermore, the diameter of the copper or copper alloy wire is D, the wire feeding speed is v, the dry extension length of the wire is fixed, and the deposition amount of the copper or copper alloy wire per unit time t is .

[0017] Beneficial technical effects: (1) The additive manufacturing process only uses blue light, which fully utilizes the advantages of blue light in melting copper or copper alloys, and makes the process control of the entire additive process simple and stable, avoiding the problems of droplet splashing, molten pool metal spraying, holes, poor consistency, low mechanical properties, etc. that may be caused by the complex process control of the composite heat source; (2) The use of multiple individually controllable lasers increases the adjustable range of laser power. For example, the power range of 1200-5000W can cope with copper or copper alloy wires of different diameters, which can improve the scalability of the additive process. At the same time, the use of high power can To relatively improve the deposition rate; (3) Compared with powder feeding, the wire feeding method can accurately control the deposition amount according to parameters such as wire feeding speed, wire diameter, and dry elongation, and the utilization rate of the wire can reach 100%, which improves the material utilization rate; at the same time, wire feeding additive has low environmental requirements and can be used in different application scenarios, while powder feeding additive is prone to explosion and is generally required to be manufactured in a closed inert gas protection environment; (4) Semiconductor lasers are used. The advantages of semiconductor lasers are small size, light weight, good reliability, long service life, low power consumption, high conversion rate, and slow attenuation. In addition, semiconductor lasers use low-voltage constant current power supply, low power failure rate, safe use, and low maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the principle diagram of the additive manufacturing method of the multi-laser blue light wire feeding of the present invention.

[0019] Figure 2 It is a comparison chart of the absorptivity of the copper or copper alloy of the present invention to blue light and infrared light.

[0020] Figure 3 It is a schematic diagram of infrared light melting copper or copper alloy to form a molten pool, where Figure 3 (a) is the infrared light energy density diagram. Figure 3 (b) is a cross-sectional view of the molten pool formed by melting copper or copper alloy using infrared light.

[0021] Figure 4 is a schematic diagram of forming a molten pool by blue light melting copper or copper alloy according to the present invention, wherein Figure 4 (a) is the blue light energy density diagram. Figure 4 (b) is a cross-sectional view of the molten pool formed by blue light molten copper or copper alloy.

[0022] Figure 5 This is a schematic diagram of a molten pool formed by melting copper or copper alloy using a composite light of infrared light and blue light, where Figure 5 (a) is the energy density diagram of the composite light of infrared light and blue light. Figure 5 (b) is a cross-sectional view of the molten pool of molten copper or copper alloy under the combined light of infrared light and blue light.

[0023] Figure 6This is an additive weld bead diagram of Example 1 of the present invention.

[0024] Figure 7 This is an additive weld bead diagram of Example 2 of the present invention.

[0025] Figure 8 This is an additive weld bead diagram of Example 3 of the present invention.

[0026] Fig. 9 Schematic diagram of the cross section of the weld (i.e., weld bead) formed by the present invention.

[0027] Fig.10 The present invention uses blue light semiconductor laser and near infrared fiber laser to perform additive manufacturing to obtain the metallographic images of the weld, weld heat affected zone and weld center area. Fig.10 (a) is a 200-fold magnification of the near-infrared fiber laser weld. Fig.10 (b) is a 500-fold magnified image of the heat-affected zone of a near-infrared fiber laser weld. Fig.10 (c) is a 500-fold magnification of the center area of ​​the near-infrared fiber laser weld. Fig.10 (d) is a 200-fold magnification of the blue light semiconductor laser weld. Fig.10 (e) is a 500-fold magnified image of the heat-affected zone of a blue semiconductor laser weld. Fig.10 (f) in the figure is a 500-fold magnified image of the central area of ​​the blue light semiconductor laser weld.

[0028] Fig.11 This is a metallographic image of a weld cross section produced by additive manufacturing using a blue semiconductor laser and a near-infrared fiber laser. Fig.11 (a) is a cross-sectional view of a near-infrared fiber laser weld. Fig.11 (b) is a cross-sectional view of the blue light semiconductor laser weld.

[0029] Fig.12 It is the principle diagram of additive manufacturing of copper or copper alloy using existing blue light and infrared light powder feeding additive manufacturing technology.

[0030] Fig.13 It is a comparative schematic diagram of the tensile strength of the base material when using blue light laser and fiber laser in the present invention.

[0031] In the figure: 1-laser; 2-wire; 3-substrate; 4-molten pool; 5-powder. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.

[0033] Reference for the implementation of the present invention Figure 1-13 .

[0034] A method for blue light wire feeding additive manufacturing of copper or copper alloy, such as Figure 1 As shown, blue light is emitted by multiple lasers 1, and the wavelength of the blue light is 450-495nm, preferably 475nm and 495nm blue light. The power output sizes of multiple lasers 1 are individually controllable, and the power range of a single laser 1 is between 200-500W, commonly 200W and 500W. Multiple lasers 1 are combined to achieve a combination of different power sizes. When the number of lasers 1 is six, and they are annularly symmetrically arranged around the wire feeding gun barrel, different power outputs can be achieved by turning on different numbers of lasers 1, such as turning on two symmetrical lasers 1, the power output is 400W-1000W, turning on four symmetrical lasers 1, the power output is 800W-2000W, and when all six lasers 1 are turned on, the power output is 1200W-3000W. Different power output sizes can be matched according to the diameter of different wires 2 and different wire feeding speeds. When the number of lasers 1 reaches 8 or 10, the total power output can reach 1600W-5000W. The spot shape of laser 1 is crescent, elliptical or circular, etc. When the spots of laser 1 are all set to be circular, the spots of multiple lasers 1 can be combined into a circle or ring; when the spot of laser 1 is crescent-shaped, multiple laser 1 spots can be combined into a circular ring; when the spot of laser 1 is elliptical, multiple laser 1 spots can be combined into a ring petal shape. Multiple lasers 1 can be arranged in layers inside and outside, so that the laser spot can cover a larger range, which can melt the wire and cover the molten pool. When the combined spot shape is ring-shaped or petal-shaped, the inner diameter of the spot is 1.6-2.0mm, the outer diameter of the spot is 2.8-3.2mm, and the spot energy is evenly distributed. When the combined spot shape is circular, the spot diameter is 1.6-2.0mm, and the spot energy is evenly distributed.

[0035] The present invention adopts blue light wire feeding technology. Figure 2 As shown in the figure, the absorption rate of copper or copper alloy solid materials to blue light can reach 65%, while the absorption rate to infrared light can only reach 5%. Experiments have shown that the absorption rate of copper or copper alloy materials to infrared light increases significantly when they are in a molten state, i.e., when a molten pool is formed, but the maximum absorption rate is 20%. Therefore, the absorption rate of copper or copper alloy materials to blue light is significantly higher than that to infrared light.

[0036] like Figure 3 As shown, a schematic diagram of infrared light melting copper or copper alloy to form a molten pool, wherein Figure 3 (a) is the infrared light energy density diagram. Figure 3 (b) is a cross-sectional view of the molten pool formed by infrared light melting copper or copper alloy. As can be seen from the figure, the energy density of infrared light exceeds , the energy distribution presents a Gaussian distribution, that is, a steeper triangle, forming a molten pool with a narrower width and a deeper melting depth, and producing droplet splashes, pores and keyholes.

[0037] like Figure 4 As shown, the schematic diagram of the blue light melting copper or copper alloy to form a molten pool of the present invention, wherein Figure 4 (a) is the blue light energy density diagram. Figure 4 (b) is a cross-sectional view of the molten pool formed by blue light melting copper or copper alloy. As can be seen from the figure, the energy density of blue light is not higher than ,The energy distribution presents a uniform flat-top distribution, thus forming an elliptical molten pool with a wider melt width and a shallow melt depth.

[0038] like Figure 5 As shown, a schematic diagram of a molten pool formed by composite light of infrared light and blue light melting copper or copper alloy, wherein Figure 5 (a) is the energy density diagram of the composite light of infrared light and blue light. Figure 5 (b) is a cross-sectional view of a molten pool of molten copper or copper alloy using a composite light of infrared light and blue light. As can be seen from the figure, the energy density of the composite light of infrared light and blue light is The energy distribution shows that the energy density in the central area of ​​the spot is , the energy density at the outer edge of the spot is . As a result, a molten pool with a wide molten width and a deep molten depth is formed, and a keyhole appears in the molten pool. Although the use of infrared light to assist blue light in melting copper or copper alloys can increase the molten width, and the use of high-power infrared light can improve the melting efficiency, it brings about the problem of deepening the melting depth to form a keyhole and unstable molten pool to form splashes due to the ultra-high power of infrared light. In addition, the absorption rate of infrared light by copper or copper alloy in solid or liquid state is significantly lower than that of blue light, which still causes the problem of low infrared light energy utilization and a large amount of infrared light being reflected, causing damage to other equipment.

[0039] The present invention adopts a copper or copper alloy wire 2, the diameter D of the wire 2 is 0.5-2.0 mm, and the wire feeding speed v is 1-8 m / min. Since the dry extension of the wire 2, that is, the length of the wire 2 extending out of the conductive nozzle at each arc starting point, is fixed and controllable, the deposition rate of the copper or copper alloy wire 2 per unit time t can be accurately controlled during the additive process, that is, the deposition amount The present invention adopts wire 2, compared with Fig.12The deposition amount of the powder 5 material shown is precisely controllable, the material utilization rate can reach 100%, and the production is safer and the cost is lower.

[0040] The implementation process of the method of the present invention is:

[0041] S1, prepare a copper or copper alloy substrate 3, clean the substrate 3 with a cleaning agent such as acetone or ethanol and dry it;

[0042] S2. Set the type, flow rate or flow rate of the inert protective gas. Select one or more of helium, argon or nitrogen as the inert protective gas, and set the flow rate to 10-20 L / min;

[0043] S3, select copper or copper alloy material, determine the diameter of wire 2, generally the diameter is 0.6-2.0mm;

[0044] S4, setting the number of blue lasers 1, their power output and incident angle, such as selecting three, six or eight blue lasers 1, and setting their output power to 200-500W;

[0045] S5, determining the positional relationship between the light spot and the wire 2, and setting the dry extension length of the wire 2;

[0046] S6. Set other additive process parameters, such as wire feeding speed, printing speed, etc.;

[0047] S7, turn on the laser 1, start wire feeding, the laser melts the wire 2 to form a molten pool 4 which is then deposited on the substrate 3, and an additive weld is formed according to the planned printing path. Example 1

[0048] Six blue lasers are used, with a total power output of 1200W, pure copper wire with a wire diameter of 0.6mm, a circular spot shape, an inner diameter of 1.6mm, an outer diameter of 2.8mm, a molten pool width of 2-3mm, a molten pool depth of 1-2mm, a printing speed of 4m / min, and an argon shielding gas flow rate of 10L / min. The printed weld is as follows Figure 6 shown. Example 2

[0049] Six blue lasers are used with a total power output of 3000W. Copper alloy wire is used with a wire diameter of 1.2mm. The spot shape is circular with an inner diameter of 1.8mm. The formed molten pool is 3-4mm wide and 2-3mm deep. The printing speed is 6m / min and the argon shielding gas flow rate is 20L / min. The printed weld is as follows: Figure 7 shown. Example 3

[0050] Eight blue lasers are used with a total power output of 5000W. Copper alloy wire is used with a wire diameter of 2.0mm. The spot shape is petal-shaped, with an inner diameter of 2.0mm and an outer diameter of 3.2mm. The formed molten pool is 4-5mm wide and 3-4mm deep. The printing speed is 8m / min and the argon shielding gas flow rate is 20L / min. The printed weld is as follows: Figure 8 shown.

[0051] The laser used in the present invention is a blue light semiconductor laser. The existing technology mostly uses infrared light fiber lasers. Compared with infrared light fiber lasers, blue light semiconductor lasers are small in size, light in weight, reliable, long in service life, low in power consumption, high in conversion rate, and slow in attenuation. In addition, semiconductor lasers use a low-voltage constant current power supply method, which has a low power failure rate, is safe to use, and has low maintenance costs. The power of the fiber laser is relatively high, up to 10KW, but it decays quickly; and the conversion rate of the fiber laser is relatively low, and the heat utilization rate is not high.

[0052] like Fig.10 As shown in the figure, a schematic diagram of a weld bead (i.e., a weld) formed by a heat source melting wire. The weld includes a weld center area and a weld heat affected zone. The weld and its heat affected zone and center area formed by additive manufacturing using infrared fiber lasers and blue semiconductor lasers are shown in the figure. Fig.10 (a) - Fig.10 As shown in (f) in .

[0053] like Fig.10 As shown in (a) in Figure 1, when near-infrared fiber laser welding is used, the 200-fold magnification of the weld microstructure shows that there is an obvious fusion line at the edge of the weld. Fig.10 The heat affected zone shown in (b) is a parallel stripe structure. This is because the molten pool solidifies in a moving state. When the heat input is large, the disturbance to the molten pool is also large. Therefore, the distance between the solidification lines becomes very small, and parallel solidification stripes appear. Fig.10 (c) is a 500-fold magnified image of the weld center. It can be seen that the weld center is honeycomb-shaped. This is because when the molten pool solidifies, the growth direction of the grains is perpendicular to the solid-liquid interface. The number of "biased grains" growing along the welding direction is large, which reduces the tensile strength and other mechanical properties. Fig.13 shown.

[0054] like Fig.10 As shown in (d), when blue light semiconductor laser welding is used, the 200-fold magnification of the weld microstructure shows that there is no obvious fusion line at the edge of the weld. Fig.10 As shown in (e), the heat affected zone is clustered columnar crystals. Fig.10 As shown in (f), the center of the weld is composed of fine equiaxed crystals, which improves the mechanical properties of the weld. Fig.13 shown.

[0055] like Fig.11 As shown in (a), the weld is conical, the upper part of the weld is wider, the lower part of the weld is narrower, and there is relative bending on both sides of the weld. The deformation is large. This is because the higher laser energy input causes the material to deform more. Fig.11 As shown in (b), the weld is trapezoidal, with a narrow upper portion and a wider lower portion. There is no obvious bending on both sides of the weld and the deformation is small. This is because the lower laser energy input results in less deformation of the material.

[0056] For those skilled in the art, the above embodiments are exemplary and non-restrictive, and the protection scope of the present invention is not limited by the above embodiments. At the same time, any figure marks in the claims should not be regarded as limiting the protection scope of the claims involved.

Claims

1. A method for additively manufacturing copper or copper alloy using blue light wire feeding, characterized in that: The blue light is composed of beams emitted by multiple independently controlled blue lasers; the method is coaxial blue laser wire feeding, that is, using the blue light to melt and deposit coaxial copper or copper alloy wires onto a substrate to form a copper or copper alloy print; the blue light is uniformly distributed as a heat source, and includes the following steps: Step 1: Select copper or copper alloy wire and determine its diameter; Step 2: Turn on multiple independently controlled blue lasers to achieve the laser target power output; Step 3: The wire feeding system feeds the wire, and the laser melts the copper or copper alloy wire to form a molten pool that is deposited on the substrate to form a weld bead. The weld bead is formed from line to surface to body, and finally a copper or copper alloy print is formed; The target power is 1200-3000W, and the diameter of the wire is 0.6-1.2mm; The spot shape formed by the light beams emitted by the multiple independently controlled blue light lasers is crescent-shaped, circular or elliptical, and the spot shape of the blue light is circular, ring-shaped or petal-shaped. When the spot shape of the blue light is ring-shaped or petal-shaped, the inner diameter of the spot is 1.6-2.0 mm, and the outer diameter of the spot is 2.8-3.2 mm; when the spot shape of the blue light is circular, the diameter of the spot is 1.6-2.0 mm, the wire feeding speed of the wire feeding system is 1-8 m / min, and the dry elongation of the copper or copper alloy wire is fixed and controllable.

2. The method for additive manufacturing of copper or copper alloy by blue light wire feeding according to claim 1, characterized in that: The multiple independently controlled blue lasers are symmetrically arranged around the wire.

3. The method for additive manufacturing of copper or copper alloy by blue light wire feeding according to claim 1, characterized in that: The diameter of the copper or copper alloy wire is D, the wire feeding speed is v, the dry extension length of the wire is fixed, and the deposition amount of the copper or copper alloy wire per unit time t is .

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