Expanded focal region laser beam hot wire deposition device

Abstract

The invention discloses a laser beam hot wire deposition device for expanding a focal region. The device comprises a laser, a lens group, a deposition working surface and a wire feeding system, the laser is used for emitting laser beams. The lens group is used for converting the laser beam into an expanded focal region laser beam, and the expanded focal region laser beam has the characteristic of transiting from an annular light spot to a continuous solid light spot in space. The deposition working face is used for receiving projection of the expanded focal region laser beam, and solid or annular light spots and a molten pool formed by continuous heating of the light spots are obtained. By adjusting the size of the light spot and the energy distribution mode, deposition morphology with different widths can be obtained. The wire feeding system is used for feeding wires along a preset path, so that the tail ends of the wires are connected with the molten pool in a liquid bridge mode after being preheated by the continuous solid light spots. Compared with the prior art, the expanded focal region laser beam hot wire deposition device has the advantages that the stability of coaxial laser inner wire feeding LMD and the material deposition efficiency are improved, and meanwhile, the temperature gradient of a deposition layer and the material deposition quality are regulated and controlled.

Description

Technical Field

[0001] The invention relates to the technical field of laser fuse deposition, and in particular to an extended focal range laser beam hot wire deposition device. Background Art

[0002] Laser melting deposition (LMD) technology is an important branch in the field of metal material additive manufacturing technology. It is divided into two categories according to the form of the feed material: powder feeding and wire feeding. Compared with powder feeding LMD, wire feeding LMD has the following advantages: First, the preparation of metal wire is easier than metal powder and it is convenient to store, so the procurement and storage costs of wires of the same material can be greatly reduced; second, according to the process characteristics, wire feeding LMD has higher material utilization (material utilization ≈ 100%) and deposition efficiency, and the additive manufacturing process is more environmentally friendly and free of powder particle pollution; finally, because the surface area ratio of metal wire is much smaller than that of metal powder, the doping of unfavorable gases such as oxygen can be significantly reduced in the open environment laser melting deposition process, further reducing the degree of oxidation of the deposited layer and reducing the porosity. Based on the above advantages, wire feeding LMD technology has received widespread attention in recent years.

[0003] At present, the wire-feeding LMD technology is still mostly based on the paraxial wire feeding method (the wire feeding direction is not coaxial with the laser beam optical axis), such as ZL 201810047415.2. The paraxial wire feeding method has a simple system layout, but it has the disadvantages of poor light-wire coupling and uneven laser energy distribution. The light-wire coupling method (multi-beam coaxial wire feeding and annular beam coaxial wire feeding) with coaxial arrangement of the light-wire can effectively solve the above problems. Among them, the coaxial wire feeding LMD in the annular beam has a more uniform energy distribution and more stable process adaptability, which is an important research direction of the coaxial wire feeding LMD technology. At present, all the working light sources of the coaxial wire feeding in the annular beam are focusing light sources. The laser source finally converges to the focus through the optical path conversion system. The heat source characteristic has the characteristics of energy concentration. However, for the wire feeding LMD, the relative position of the wire end and the laser heat source is often limited. Generally, the hollow diameter of the annular spot is exactly the wire diameter as the working spot to obtain the best deposition effect.

[0004] In the wire-feeding LMD process, the cold wire entering the rapidly solidified molten pool will cause a sudden chilling of the molten pool, and even the wire will not have time to melt and poke the bottom, causing the wire to be squeezed out by the bottom of the molten pool due to the force. The preheated metal wire entering the molten pool can assist in rapid melting and form a stable melt convection, thereby further improving the LMD deposition efficiency. On the other hand, in the case of cold wire, the end of the wire cannot accurately enter the predetermined vertical area due to its own curvature after the insufficiently straightened wire is sent out from the wire feeding nozzle, affecting the wire feeding accuracy. Studies have shown that under the condition of wire preheating, the liquid wire will have a tendency to adhere to the center of the molten pool at the expected position under the tension of the substrate molten pool, provided that the molten pool size is large enough and the molten droplets are within the liquid molten pool area. This hot wire transition adaptive phenomenon helps to improve the accuracy and stability of the LMWD forming process.

[0005] At present, the wire preheating methods can be mainly divided into resistive heating and inductive heating in principle, but no matter which method is used, additional auxiliary preheating devices or additional heat sources are required. For example, ZL 201811291854.4 and ZL201910577908.1 both use induction coils or add a second laser heat source to preheat the wire. The above methods require the introduction of a complete set of inductive / resistive heating wire equipment or additional laser sources. And it is obvious that the above methods all use the side-axis wire feeding forming technology. This is because the side-axis wire feeding processing head is often not compact in structure, and there is enough space to arrange other auxiliary hot wire devices such as the second heat source in the area where the wire needs to be preheated before the deposition position. In addition, the method of preheating the wire by adding auxiliary preheating devices often results in a longer preheating interruption distance. The excessively long preheating interruption reduces the original wire preheating effect and reduces the energy utilization rate. Inappropriate preheating power selection can also easily lead to process failure.

[0006] For the annular light coaxial wire feeding processing head, since the deposition position is located in the beam focusing area, there is often not enough space for the arrangement of additional devices in the wire preheating area; at the same time, in order to avoid interference in the optical path, it is difficult to connect the area inside the optical path that needs to heat the wire with the external preheating system. In order to solve the wire preheating problem of the annular light coaxial wire feeding LMD technology, the inventors previously invented a coaxial feeding laser cladding device (ZL 201710059713.9), in which the homologous laser beam is divided into two laser beams through the same conical reflector with different cone reflection angles, one laser beam is used to act on the working interface to form a molten pool to achieve material deposition, and the other laser beam acts on the feeding material to preheat it. However, the wire preheating range of the invention is limited, there is an unpreheated area between the wire preheating area and the molten pool area, and the continuous preheating of the wire before entering the molten pool cannot be achieved. In addition, the method cannot autonomously adjust the energy distribution of the two laser beams with different functions, which is not conducive to the development of LMD processes for multiple materials. Summary of the invention

[0007] The purpose of the present invention is to provide an extended focal range laser beam hot wire deposition device to improve the stability and material deposition efficiency of coaxial laser internal wire feeding LMD, while achieving the regulation of the temperature gradient of the deposition layer and the material deposition quality.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention discloses an extended focal range laser beam hot wire deposition device, comprising:

[0010] A laser, wherein the laser is used to emit a laser beam;

[0011] A lens assembly, wherein the lens assembly is used to transform the laser beam into an extended focus laser beam, wherein the extended focus laser beam has a feature of transitioning from an annular light spot to a continuous solid light spot in space;

[0012] A deposition working surface, the deposition working surface is used to receive the projection of the extended focal range laser beam, obtain a solid or annular light spot and a molten pool formed by continuous heating of the light spot; by adjusting the position of the deposition working surface in the extended focal range laser beam, the size and energy distribution mode (solid or annular) of the light spot can be changed, thereby obtaining deposition morphologies with different widths;

[0013] A wire feeding system is used to feed wire along a preset path so that the end of the wire is connected to the molten pool in the form of a liquid bridge after being preheated by the continuous solid light spot.

[0014] Preferably, the mirror assembly includes a beam splitter and a reflector, the beam splitter has a conical outer reflective surface, the reflector has a conical inner reflective surface, and the outer reflective surface is coaxial with the inner reflective surface; the outer reflective surface is used to expand the incident laser beam; the inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain the extended focal range laser beam.

[0015] Preferably, the mirror assembly includes a beam splitter and a reflector, the beam splitter has a conical outer reflective surface, the reflector has a parabolic inner reflective surface, and the outer reflective surface is coaxial with the inner reflective surface; the outer reflective surface is used to expand the incident laser beam; the inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain the extended focal range laser beam.

[0016] Preferably, the lens assembly includes a beam splitting cone lens, a collimating lens and a beam combining cone lens, and the beam splitting cone lens, the collimating lens and the beam combining cone lens are arranged in sequence and on the same axis; the beam splitting cone lens is used to expand the incident laser beam, the collimating lens is used to collimate the laser expanded by the beam splitting cone lens, and the beam combining cone lens is used to combine the collimated laser emitted by the collimating lens to obtain the extended focal range laser beam.

[0017] Preferably, the mirror assembly includes a beam splitter, a reflector and a beam-combining conical lens, the beam splitter has a conical outer reflective surface, the reflector has a conical inner reflective surface, the outer reflective surface, the inner reflective surface and the beam-combining conical lens are coaxial; the outer reflective surface is used to expand the incident laser beam, and the inner reflective surface is used to collimate the laser expanded by the outer reflective surface; the beam-combining conical lens is used to combine the collimated laser obtained by the inner reflective surface to obtain the extended focal range laser beam.

[0018] Preferably, the mirror assembly further comprises a plane reflector or an integrating mirror, and the plane reflector or the integrating mirror is used to change the process direction or laser energy distribution of the extended focal range laser beam.

[0019] Preferably, the mirror assembly further comprises an adjusting mechanism, and the adjusting mechanism is used to adjust the position of one or more mirror bodies in the mirror assembly to adjust the extended focal range laser beam.

[0020] Preferably, the optical axis of the extended focal range laser beam is perpendicular to the deposition working surface.

[0021] Preferably, the length of the continuous solid light spot along the optical axis of the extended focal laser beam is called an effective preheating length, and the effective preheating length is greater than 5 mm.

[0022] Preferably, the preheating length of the wire is not greater than 20 mm.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] In the present invention, a part of the extended focal laser beam is irradiated on the wire entering the continuous solid spot, which plays a role in preheating the wire, and another part of the extended focal laser beam is irradiated on the deposition work surface to form a molten pool on the deposition work surface. The wire is continuously preheated and enters the substrate molten pool in the form of a semi-molten state of hot wire to form a liquid bridge, thereby achieving stable and efficient material deposition. At the same time, by preheating the wire, the chilling effect of the wire on the molten pool can be significantly reduced, the temperature gradient and internal stress can be reduced, the stable formation of the liquid bridge transition can be promoted, and the deposition efficiency and deposition quality of the material can be significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the structure of an extended focal range laser beam hot wire deposition device according to an embodiment of the present invention;

[0027] Figure 2 Another structural schematic diagram of an extended focal range laser beam hot wire deposition device according to an embodiment of the present invention;

[0028] Figure 3 This is the first example of a mirror assembly;

[0029] Figure 4 is a second example of a mirror assembly;

[0030] Figure 5 is the third example of a mirror assembly;

[0031] Figure 6 is the fourth example of a mirror assembly;

[0032] Figure 7 is the fifth example of a mirror assembly;

[0033] Figure 8 Schematic diagram of different positional relationships between the extended focal laser beam and the deposition work surface;

[0034] Fig. 9 for Figure 2 Schematic diagram of the light spot in part A;

[0035] Fig.10 It is a schematic diagram of a hollow light spot with a high duty cycle of a common annular light beam in the prior art;

[0036] Fig.11 This is a photo of the light spot when the extended focal range laser beam hot wire deposition device according to an embodiment of the present invention is working;

[0037] Fig.12 This is a photo of the light spot during ordinary annular beam cold filament deposition.

[0038] In the figure: 1-laser; 11-collimating mirror; 2-mirror group; 3-deposition working surface; 4-wire feeding system; 5-motion actuator; 6-processing head; 21-beam splitter; 22-reflector; 23-beam splitting cone lens; 24-collimating lens; 25-beam combining cone lens; 41-wire. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The purpose of the present invention is to provide an extended focal range laser beam hot wire deposition device to improve the stability and material deposition efficiency of coaxial laser internal wire feeding LMD, while achieving the regulation of the temperature gradient of the deposition layer and the material deposition quality.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Reference Figures 1 to 9 , Fig.11 This embodiment provides an extended focal range laser beam hot wire deposition device, including a laser 1, a lens group 2, a deposition working surface 3 and a wire feeding system 4.

[0043] The laser 1 is used to emit a laser beam. The lens group 2 is used to transform the laser beam into an extended focal range laser beam, which has the characteristic of transitioning from an annular spot to a continuous solid spot in space. The deposition working surface 3 is used to receive the projection of the extended focal range laser beam to obtain a solid or annular spot and a molten pool formed by continuous heating of the spot. By adjusting the position of the deposition working surface 3 in the extended focal range laser beam, the size of the spot and the energy distribution mode (solid or annular) can be changed to obtain deposition morphologies with different widths. The wire feeding system 4 is used to feed the wire 41 along a preset path so that the end of the wire 41 is connected to the molten pool in the form of a liquid bridge after being preheated by the continuous solid spot. The end of the wire 41 referred to in this embodiment refers to the end of the wire 41 close to the deposition working surface 3, which only refers to the end of its solid part and does not include the liquid bridge.

[0044] The working principle of the extended focal range laser beam hot wire deposition device of this embodiment is as follows:

[0045] A portion of the extended focal laser beam is irradiated on the wire 41 entering the continuous solid spot, which plays a role in preheating the wire 41. Another portion of the extended focal laser beam is irradiated on the deposition work surface 3, forming a molten pool on the deposition work surface 3. The wire 41 is continuously preheated and enters the substrate molten pool in the form of a semi-molten hot wire to form a liquid bridge, achieving stable and efficient material deposition. At the same time, by preheating the wire 41, the chilling effect of the wire 41 on the molten pool can be significantly reduced, the temperature gradient and internal stress can be reduced, the stable formation of the liquid bridge transition can be promoted, and the deposition efficiency and deposition quality of the material can be significantly improved.

[0046] If the laser beam emitted by the laser 1 is a collimated laser beam, it can directly enter the lens assembly 2 . Figure 1 , Figure 2 In the figure, the laser beam emitted by the laser 1 is a diffuse laser beam, which is transformed into a collimated laser beam after being adjusted by the collimator 11 and then enters the lens group 2.

[0047] Figure 2 In the embodiment, any two of the x-axis, y-axis, and z-axis are perpendicular to each other, the z-axis is parallel to the optical axis of the extended focal laser beam, and the z-axis is perpendicular to the deposition work surface 3. In the continuous solid spot, the wire 41 extends along the optical axis of the continuous solid spot. The continuous solid spot of the extended focal laser beam has a minimum spot position, and the spot area gradually increases from this position upward or downward.

[0048] Figure 8 The continuous solid spot on the upper side of the minimum spot position is shown; and the size change of the spot on the deposition work surface 3 when the deposition work surface 3 corresponds to three different z-axis coordinates in this area (the continuous solid spot on the upper side of the minimum spot position). By changing the size of the spot and the energy distribution mode of the spot, deposition morphologies with different widths can be obtained; and the situation when the end of the wire 41 corresponds to three different z-axis coordinates in this area. It is not difficult to see that since the cross-sectional area of ​​the wire 41 remains unchanged, when the radius of the spot decreases, the laser energy distributed on the wire 41 increases, and the laser energy distributed on the deposition work surface 3 decreases. According to this rule, by changing the z-axis coordinate of the deposition work surface 3, the distribution ratio of the laser energy in the preheating of the wire 41 and the heating of the deposition work surface 3 can be adjusted to achieve the desired effect. Similarly, it is not difficult to see that when the end of the wire 41 is outside the area, the wire 41 cannot be preheated by the extended focal laser beam; when the end of the wire 41 is within the area, as the distance between the end of the wire 41 and the deposition work surface 3 decreases, the preheating length of the wire 41 increases. When the supply speed of the wire 41 remains unchanged, the longer the preheating length of the wire 41 is, the longer it is preheated, and the more laser energy the wire 41 per unit length receives. Therefore, by adjusting the z-axis coordinate corresponding to the end of the wire 41, the preheating effect of the wire 41 can be adjusted. It should be noted that when adjusting the z-axis coordinate of the end of the wire 41, the end of the wire 41 cannot be too far away from the deposition work surface 3 to ensure the stable formation of the liquid bridge transition.

[0049] Fig. 9 It is shown in Figure 2 The change of the light spot in area A along the z-axis. Fig.10 Compared with the spot in the image, the laser energy distribution is more uniform due to the use of an extended focal range laser beam.

[0050] There are various types of lens groups 2 that can transform a laser beam into an extended focal range laser beam, and those skilled in the art can select one according to actual needs. Figure 3 to Figure 7 Five examples of the mirror group 2 are shown, but the actual implementation is not limited thereto.

[0051] As a possible example, see Figure 3 , the mirror assembly 2 includes a beam splitter 21 and a reflector 22. The beam splitter 21 has a conical outer reflective surface, and the reflector 22 has a conical inner reflective surface. The outer reflective surface is coaxial with the inner reflective surface. The outer reflective surface is used to expand the incident laser beam. The inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain an extended focal range laser beam.

[0052] As a possible example, see Figure 4 , the mirror assembly 2 includes a beam splitter 21 and a reflector 22. The beam splitter 21 has a conical outer reflective surface, and the reflector 22 has a parabolic inner reflective surface. The outer reflective surface is coaxial with the inner reflective surface. The outer reflective surface is used to expand the incident laser beam. The inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain an extended focal range laser beam.

[0053] As a possible example, see Figure 5 The lens assembly 2 includes a beam splitting aconic lens 23, a collimating lens 24 and a beam combining aconic lens 25, which are arranged in sequence and on the same axis. The beam splitting aconic lens 23 is used to expand the incident laser beam, the collimating lens 24 is used to collimate the laser beam expanded by the beam splitting aconic lens 23, and the beam combining aconic lens 25 is used to combine the collimated laser beams emitted by the collimating lens 24 to obtain an extended focal range laser beam.

[0054] As a possible example, see Figure 6 , the mirror assembly 2 includes a beam splitter 21, a reflector 22 and a beam-combining aconic lens 25. The beam splitter 21 has a conical outer reflective surface, the reflector 22 has a conical inner reflective surface, and the outer reflective surface, the inner reflective surface and the beam-combining aconic lens 25 are coaxial. The outer reflective surface is used to expand the incident laser beam, and the inner reflective surface is used to collimate the laser beam expanded by the outer reflective surface. The beam-combining aconic lens 25 is used to combine the collimated laser beam obtained by the inner reflective surface to obtain an extended focal range laser beam.

[0055] As a possible example, see Figure 7 The mirror assembly also includes a plane reflector or an integrating mirror, which is used to change the process direction or laser energy distribution of the extended focal range laser beam.

[0056] As a possible example, the lens assembly 2 further includes an adjustment mechanism, which is used to adjust the position of one or more lens bodies in the lens assembly 2 to adjust the extended focal range laser beam. Figure 3 , Figure 4 and Figure 6 The mirror assembly 2 shown in the figure can be adjusted by adjusting the relative distance between the beam splitter 21 and the reflector 22 along the z-axis. Figure 5 In the lens assembly 2 shown, the adjustment here can be to adjust the relative distance between the beam splitting cone lens 23 and the collimating lens 24 along the z-axis, or the relative distance between the collimating lens 24 and the beam combining cone lens 25 along the z-axis. Figure 3 , Figure 4 , Figure 6 The reflector 22 in the Figure 5 In the beam-combining cone lens 25, the moving direction of the adjustment mechanism is the z-axis direction.

[0057] As a possible example, see Figure 1 , Figure 2 , the optical axis of the extended focus laser beam is perpendicular to the deposition work surface 3, and the shape of the solid light spot irradiated on the deposition work surface 3 is circular. It can be understood that, according to different actual needs, the optical axis of the extended focus laser beam can also form a certain angle (for example, an angle less than 10°) with the z-axis.

[0058] As a possible example, in this embodiment, the cone vertex angle of the outer reflection surface is not less than 90°. Specifically, Figure 3 , Figure 6 In the corresponding example, the cone vertex angle of the outer reflection surface is 100°. Figure 4 In the corresponding example, the cone vertex angle of the outer reflection surface is 90°.

[0059] As a possible example, see Figure 1 In this embodiment, the extended focal laser beam hot wire deposition device further includes a motion actuator 5. Figure 2 The laser 1 and the lens group 2 are integrated on the processing head 6, and the motion actuator 5 is used to move the processing head 6. When the motion actuator 5 moves the processing head 6 parallel to the z-axis, the size of the light spot on the deposition work surface 3 can be adjusted. When the motion actuator 5 moves the processing head 6 in a direction perpendicular to the z-axis, the light spot can be moved on the deposition work surface 3.

[0060] As a possible example, in this embodiment, the length of the continuous solid light spot along the optical axis of the extended focal laser beam is called the effective preheating length, and the effective preheating length is greater than 5 mm to maximize the preheating effect.

[0061] As a possible example, in this embodiment, the preheating length of the wire 41 is not greater than 20 mm. It is understandable that the preheating length of the wire 41 can be flexibly adjusted, especially when the supply speed of the wire 41 changes, the preheating length of the wire 41 can be adjusted accordingly to keep the heat received per unit length unchanged or approximately unchanged.

[0062] As a possible example, in this embodiment, refer to Figure 1 to Figure 7 In the continuous solid light spot, the wire 41 extends along the optical axis of the continuous solid light spot, that is, the wire 41 is coaxial with the extended focal range laser beam.

[0063] The following is an exemplary description of the specific parameters of the extended focal laser beam hot wire deposition device of this embodiment when it is working: the motion actuator 5 moves the processing head 6 in a direction perpendicular to the z-axis, and the moving speed of the processing head 6 is 10mm / s, forming a single cladding track with a length of 40mm on the deposition work surface 3. The output power of the laser 1 is 2600W, and the working distance is 6mm. At this time, the diameter of the solid spot on the deposition work surface 3 is 8mm. The material of the wire 41 is Ti6Al4V titanium alloy, with a diameter of 1mm and a preheating length of 6mm. About 84% of the energy of the extended focal beam acts on the deposition work surface 3 in a deep melting mode to form a molten pool, and the other 16% of the energy acts on the wire 41 and preheats the wire 41 in a thermal conduction mode.

[0064] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An extended focal range laser beam hot wire deposition device, characterized in that: include: A laser, wherein the laser is used to emit a laser beam; A lens assembly, wherein the lens assembly is used to transform the laser beam into an extended focus laser beam, wherein the extended focus laser beam has a feature of transitioning from an annular light spot to a continuous solid light spot in space; A deposition working surface, the deposition working surface is used to receive the projection of the extended focal range laser beam to obtain a solid or annular light spot and a molten pool formed by continuous heating of the light spot; A wire feeding system is used to feed wire along a preset path so that the end of the wire is connected to the molten pool in the form of a liquid bridge after being preheated by the continuous solid light spot.

2. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The mirror assembly includes a beam splitter and a reflector, the beam splitter has a conical outer reflective surface, the reflector has a conical inner reflective surface, and the outer reflective surface is coaxial with the inner reflective surface; the outer reflective surface is used to expand the incident laser beam; the inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain the extended focal range laser beam.

3. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The mirror assembly includes a beam splitter and a reflector, the beam splitter has a conical outer reflective surface, the reflector has a parabolic inner reflective surface, and the outer reflective surface is coaxial with the inner reflective surface; the outer reflective surface is used to expand the incident laser beam; the inner reflective surface is used to combine the laser beam expanded by the outer reflective surface to obtain the extended focal range laser beam.

4. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The lens assembly includes a beam splitting cone lens, a collimating lens and a beam combining cone lens, which are arranged in sequence and on the same axis; the beam splitting cone lens is used to expand the incident laser beam, the collimating lens is used to collimate the laser expanded by the beam splitting cone lens, and the beam combining cone lens is used to combine the collimated laser emitted by the collimating lens to obtain the extended focal range laser beam.

5. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The mirror assembly includes a beam splitter, a reflector and a beam-combining conical lens. The beam splitter has a conical outer reflective surface, the reflector has a conical inner reflective surface, and the outer reflective surface, the inner reflective surface and the beam-combining conical lens are coaxial. The outer reflective surface is used to expand the incident laser beam, and the inner reflective surface is used to collimate the laser expanded by the outer reflective surface. The beam-combining conical lens is used to combine the collimated laser obtained by the inner reflective surface to obtain the extended focal range laser beam.

6. The extended focal range laser beam hot wire deposition device according to any one of claims 2 to 5, characterized in that: The mirror assembly further includes a plane reflecting mirror or an integrating mirror, and the plane reflecting mirror or the integrating mirror is used to change the process direction or laser energy distribution of the extended focal range laser beam.

7. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The mirror assembly further comprises an adjusting mechanism, and the adjusting mechanism is used to adjust the position of one or more mirror bodies in the mirror assembly so as to adjust the extended focal range laser beam.

8. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The optical axis of the extended focal range laser beam is perpendicular to the deposition working surface.

9. The extended focal range laser beam hot wire deposition device according to claim 8, characterized in that: The length of the continuous solid light spot along the optical axis of the extended focal laser beam is called an effective preheating length, and the effective preheating length is greater than 5 mm.

10. The extended focal range laser beam hot wire deposition device according to claim 1, characterized in that: The preheating length of the wire is not more than 20 mm.

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