Laser rotary scanning coaxial melting device and method

Abstract

The invention provides a laser rotary scanning coaxial melting device and method.The device comprises a laser machining head and an additive manufacturing system, and the additive manufacturing system is used for continuously conveying additive manufacturing raw materials in the axial direction of the laser machining head; the laser processing head comprises a laser, a galvanometer system, a conscope and an annular reflector; the laser device is used for generating parallel laser, the conscope is provided with a concave parabolic reflecting surface, the galvanometer system is used for dynamically focusing the parallel laser to form working laser and reflecting the working laser to different positions of the concave parabolic reflecting surface, the working laser is reflected to the annular reflecting mirror by the concave parabolic reflecting surface, and the working laser is reflected by the annular reflecting mirror. And the light spots of the working laser act on the additive manufacturing raw materials, and the additive manufacturing raw materials are coaxially melted. According to the invention, rotary scanning of laser and coaxial melting of additive manufacturing raw materials can be realized, the structure is simple, optical devices are easy to manufacture, the working stability is high, and the process error-tolerant rate is high.

Description

Technical Field

[0001] The present invention relates to the technical field of laser additive manufacturing, and more specifically to a laser rotary scanning coaxial melting device and method. Background Art

[0002] The existing laser beam splitting method and device for coaxial fuse powder melting generally splits the laser beam through a four-segment reflector, and then reflects and focuses it onto the vertically falling wire or powder, heats and melts the wire or powder, and realizes additive manufacturing. It has the following problems: First, when the high-energy-density laser is irradiated on the edge or vertex of the four-segment reflector, the high temperature will cause ablation of the edge and vertex of the four-segment reflector, affecting the life of the laser processing head; second, the sharp vertex of the four-segment reflector is not easy to process the coating, and it is very easy to be ablated and damaged or the reflection is unstable during the application process, affecting the overall stability of the device. Third, in the prior art, when the height of the laser processing head is not changed, the focal position of the laser generated by the laser processing head on the wire or powder is basically on the same plane of equal height, and the precision requirement for the focusing position is relatively high. When the precision does not meet the requirements, the quality of the final molten deposited layer will be poor. Summary of the invention

[0003] 1. Technical issues to be resolved

[0004] The technical problem to be solved by the present invention is that the prior art has the problems that the optical device is easily ablated, the welding stability is poor, and the molding quality of the molten deposited layer is poor.

[0005] (II) Technical solution

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In the first aspect, the present invention provides a laser rotary scanning coaxial melting device, comprising a laser processing head and an additive manufacturing system, wherein the additive manufacturing system is used to continuously convey additive manufacturing raw materials along the axial direction of the laser processing head; the laser processing head comprises a laser, a galvanometer system, a conical mirror and an annular reflector; the laser is used to generate parallel lasers, the conical mirror has a concave parabolic reflective surface, the galvanometer system is used to dynamically focus the parallel lasers to form working lasers, and reflect the working lasers to different positions of the concave parabolic reflective surface, the working lasers are reflected by the concave parabolic reflective surface to the annular reflector, and the annular reflector reflects the working lasers so that the light spot of the working lasers acts on the additive manufacturing raw materials to coaxially melt the additive manufacturing raw materials.

[0008] Preferably, the galvanometer system includes a dynamic focusing mirror, an X-direction galvanometer and a Y-direction galvanometer; the dynamic focusing mirror is used to dynamically focus the working laser to form a working laser, the X-direction galvanometer can deflect along the X-direction and reflect the working laser, the Y-direction galvanometer can deflect along the Y-direction and receive the working laser reflected by the X-direction galvanometer, and reflect the working laser to the concave parabolic reflecting surface.

[0009] Preferably, the laser comprises a laser source, an optical fiber and a laser collimator, the optical fiber connects the laser source and the laser collimator, the laser source is used to generate laser, the laser is transmitted along the optical fiber to the laser collimator, and the laser collimator collimates the laser to form parallel laser.

[0010] Preferably, the laser processing head further comprises a shell, the galvanometer system, the conical mirror and the annular reflector are all arranged in the shell, and the shell is provided with an arc-shaped channel for the working laser to pass through.

[0011] Preferably, the laser rotary scanning coaxial melting device further comprises a robot, and the robot is connected to the laser processing head.

[0012] Preferably, the additive manufacturing raw material is wire and / or powder.

[0013] In a second aspect, the present invention further provides a laser rotary scanning coaxial melting method, which uses the laser rotary scanning coaxial melting device described in any one of the above technical solutions to coaxially melt the additive manufacturing raw material; the method comprises the following steps:

[0014] The parallel laser is injected into the galvanometer system;

[0015] The galvanometer system dynamically focuses the parallel laser to form a working laser, and reflects the working laser to the concave parabolic reflecting surface;

[0016] The concave parabolic reflecting surface reflects the working laser to the annular reflecting mirror, and the annular reflecting mirror reflects the working laser so that the light spot of the working laser acts on the additive manufacturing raw material;

[0017] The galvanometer system continuously deflects and reflects the working laser, and the light spots of the working laser are superimposed in the axial direction to form a cylindrical processing area.

[0018] Preferably, the laser rotary scanning coaxial melting method further comprises the steps of: slicing the digital model of the additively manufactured part in layers, forming a scanning track according to the width and overlap rate of a single melt track, and driving the laser processing head to move along the scanning track.

[0019] (III) Beneficial effects

[0020] The above technical solution of the present invention has at least the following advantages:

[0021] 1. In the present invention, the galvanometer in the galvanometer system vibrates at a high frequency, and the galvanometer system deflects and reflects the working laser to different positions on the concave parabolic reflective surface. The concave parabolic reflective surface has different curvatures at different positions in the height direction. When the working laser is reflected to a higher position on the concave parabolic reflective surface, the working laser is reflected by the concave parabolic reflective surface and the annular reflector in turn, and acts on the higher position of the deposition plane. When the working laser is reflected to a lower position on the concave parabolic reflective surface, the working laser is reflected by the concave parabolic reflective surface and the annular reflector in turn, and acts on the lower position of the deposition plane. The working laser is deflected and reflected by the galvanometer system to different positions in the circumference of the concave parabolic reflective surface, and then reflected by the concave parabolic reflective surface and the annular reflector, forming a rotating annular beam that intersects at a preset convergence point. The rotating annular beams of different heights are superimposed along the axial direction, thereby forming a laser processing area similar to a cylindrical shape in the axial direction of the laser processing head, rather than a flat spot. In the cylindrical laser processing area, the melting processing of additive manufacturing raw materials can be achieved, thereby providing a greater fault tolerance, reducing the requirements for equipment processing accuracy, and improving the quality of the formed molten deposition layer. In addition, the use of a galvanometer system for rotating scanning has an effect of increasing the depth of the final processing laser convergence focus, and a greater focal depth can be obtained in actual processing.

[0022] 2. In the present invention, a quadrangular pyramid-shaped four-part reflector is not used to control the laser beam path, so there will be no ablation problem caused by the laser acting on the edge position and vertex position of the four-part reflector, thereby improving the service life of the optical device and ensuring the stability of the additive manufacturing process.

[0023] 3. In the present invention, the structures of the galvanometer system, the conical mirror and the annular reflector are simple. The simplified structure can improve the stability of the optical path, and there are not many edges, which is convenient for coating and can reduce the difficulty of lens production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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.

[0025] Figure 1 It is a schematic structural diagram of a laser rotary scanning coaxial melting device provided in an embodiment of the present invention.

[0026] Figure 2It is a schematic diagram of the bottom structure of the shell provided by an embodiment of the present invention.

[0027] The reference numerals in the figures are:

[0028] 1. Laser; 2. Galvanometer system; 3. Conical mirror; 4. Annular reflector; 5. Shell; 6. Manipulator; 7. Wire and powder feeding tube; 8. Melt deposition layer; 9. Substrate; 11. Optical fiber; 12. Laser collimator; 21. Dynamic focusing mirror; 22. X-axis galvanometer; 23. Y-axis galvanometer; 51. Arc channel. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly located on the other element or indirectly located on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0031] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention, and do not indicate that a device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating relative importance or indicating the number of technical features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The specific implementation of the present invention is described in more detail below in conjunction with specific embodiments:

[0033] like Figure 1As shown, an embodiment of the present invention provides a laser rotary scanning coaxial melting device, comprising a laser processing head and an additive manufacturing system, the additive manufacturing system is used to continuously convey additive manufacturing raw materials along the axial direction of the laser processing head; the laser processing head comprises a laser 1, a galvanometer system 2, a conical mirror 3 and an annular reflector 4; the laser 1 is used to generate parallel lasers, the conical mirror 3 has a concave parabolic reflecting surface, the galvanometer system 2 is used to dynamically focus the parallel lasers to form working lasers, and reflect the working lasers to different positions of the concave parabolic reflecting surface, the working lasers are reflected by the concave parabolic reflecting surface to the annular reflector 4, the annular reflector 4 reflects the working lasers, so that the light spot of the working lasers acts on the additive manufacturing raw materials, and the additive manufacturing raw materials are coaxially melted.

[0034] The galvanometer system 2 vibrates at a high frequency, and the galvanometer system 2 deflects and reflects the working laser to different positions on the concave parabolic reflective surface. The concave parabolic reflective surface has different curvatures at different positions in the height direction. When the working laser is reflected to a higher position on the concave parabolic reflective surface, the working laser is reflected by the concave parabolic reflective surface and the annular reflector in turn, and acts on a higher position of the deposition plane. When the working laser is reflected to a lower position on the concave parabolic reflective surface, the working laser is reflected by the concave parabolic reflective surface and the annular reflector in turn, and acts on a lower position of the deposition plane. The working laser is deflected and reflected by the galvanometer system 2 to different positions of the circumference of the concave parabolic reflective surface, and then reflected by the concave parabolic reflective surface and the annular reflector, forming a rotating annular beam that intersects at a preset convergence point. The rotating annular light beams of different heights are superimposed along the axial direction, thereby forming a laser processing area similar to a cylindrical shape in the axial direction of the laser processing head, rather than a plane light spot. In the cylindrical laser processing area, the melting processing of additive manufacturing raw materials can be achieved, thereby providing a greater fault tolerance rate and reducing the requirements for equipment processing accuracy. Moreover, the use of the galvanometer system 2 for rotating scanning has the effect of increasing the depth of the final processing laser convergence focus, and a greater focal depth can be obtained in actual processing. In this embodiment, the working laser will only act on the middle curved surface of the concave parabolic reflector, and will not act on the vertex position. Therefore, the working mechanism will not produce ablation effect on the optical device.

[0035] In one embodiment, the galvanometer system 2 includes a dynamic focusing mirror 21, an X-direction galvanometer 22, and a Y-direction galvanometer 23; the dynamic focusing mirror 21 is used to dynamically focus the working laser to form the working laser, the X-direction galvanometer 22 can deflect and reflect the working laser in the X-direction, the Y-direction galvanometer 23 can deflect and receive the working laser reflected by the X-direction galvanometer 22 in the Y-direction, and reflect the working laser to the concave parabolic reflection surface. The X-direction galvanometer 22 has an X-direction vibration motor and an X-direction plane reflection mirror connected to the X-direction vibration motor, the X-direction vibration motor can drive the X-direction plane reflection mirror to vibrate at a high frequency, so that the working laser is deflected in the X-direction; similarly, the Y-direction galvanometer 23 has a Y-direction vibration motor and a Y-direction plane reflection mirror connected to the Y-direction vibration motor, the Y-direction vibration motor can drive the Y-direction plane reflection mirror to vibrate at a high frequency, so that the working laser is deflected in the Y-direction, thereby realizing the deflection and reflection of the working laser to different spatial positions of the concave parabolic reflection surface.

[0036] In one embodiment, the laser 1 includes a laser source (not shown), an optical fiber 11 and a laser collimator 12. The optical fiber 11 connects the laser source and the laser collimator 12. The laser source is used to generate laser light. The laser light is transmitted along the optical fiber 11 to the laser collimator 12. The laser collimator 12 collimates the laser light to form parallel laser light.

[0037] In one embodiment, if Figure 1 and Figure 2 As shown, the laser processing head further comprises a housing 5, wherein the galvanometer system 2, the conical mirror 3 and the annular reflector 4 are all arranged in the housing 5, and an arc-shaped channel 51 is provided on the housing 5 for the working laser to pass through.

[0038] In one embodiment, the laser rotary scanning coaxial melting device further includes a robot arm 6 connected to the laser processing head.

[0039] In one embodiment, the additive manufacturing raw material is wire; in another embodiment, the additive manufacturing raw material is powder; in another embodiment, the additive manufacturing raw material is wire and powder. Specifically, a support 52 is provided at the bottom of the housing 5, and the additive manufacturing system has a wire and powder feeding tube 7 for conveying the additive manufacturing raw material, and the wire and powder feeding tube 7 is fixedly connected to the support 52.

[0040] In a second aspect, the present invention further provides a laser rotary scanning coaxial melting method, which uses any one of the laser rotary scanning coaxial melting devices in the above technical solutions to coaxially melt additive manufacturing raw materials; the method comprises the following steps:

[0041] The parallel laser is injected into the galvanometer system 2;

[0042] The galvanometer system 2 dynamically focuses the parallel laser to form a working laser, and reflects the working laser to the concave parabolic reflection surface;

[0043] The concave parabolic reflective surface reflects the working laser to the annular reflector 4, and the annular reflector 4 reflects the working laser so that the light spot of the working laser acts on the additive manufacturing raw material;

[0044] The galvanometer system 2 continuously deflects and reflects the working laser, and the light spots of the working laser are superimposed in the axial direction to form a cylindrical processing area.

[0045] In one of the embodiments, the laser rotary scanning coaxial melting method further includes the steps of: slicing the digital model of the additively manufactured part in layers, forming a scanning track according to the width and overlap rate of a single melt track, and driving the laser processing head to move along the scanning track.

[0046] The following is a specific embodiment provided by this application:

[0047] This example takes titanium alloy laser melting deposition as an example, and its specific implementation process is:

[0048] 1. The digital model of the titanium alloy part to be formed is sliced ​​into layers, and a scanning track is formed according to the width of a single melt channel and an overlap rate of 80%.

[0049] 2. Fix the substrate 9 on the workbench, use the robot 6 to clamp the laser processing head, place it above the substrate 9, keep it level, measure the laser convergence point and keep it 10 mm above the surface to be deposited.

[0050] 3. A 0.8-1 mm titanium alloy wire is fed into the bottom of the laser processing head through the wire feeding and powder feeding tube 7, or a 15-150 μm titanium alloy powder is fed out through an airborne powder feeder using the wire feeding and powder feeding tube 7. The wire / powder passes through the laser convergence point and is melted and deposited on the substrate 9 to form a molten deposition layer 8.

[0051] 4. The entire additive manufacturing process is carried out in an inert atmosphere protection box. Laser melting deposition begins when the oxygen content in the inert atmosphere protection box is lower than 1000PPM.

[0052] 5. Turn on the wire feeder / powder feeder and the laser processing head. The laser rotates and scans to converge and melt the coaxially fed wire or vertically falling powder. The laser power is 300-1000W. The wire and powder feeding tube 7 scans and moves at a speed of 10-20mm / s. The robot 6 performs melting and deposition according to the scanning trajectory generated for each layer.

[0053] 6. The robot 6 raises the layer thickness by 30-100 μm to start the next layer of repeated melting and deposition until all scanning tracks of the digital model of the part are completed.

[0054] 7. Turn off the laser and wire feeder / powder feeder, wait for the part to cool to room temperature, and then take it out of the inert atmosphere protection box to obtain the additively manufactured part.

[0055] The present invention is not only applicable to laser additive manufacturing, but also to laser repair technology and laser surface cladding technology.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser rotary scanning coaxial melting device, It is characterized in that It comprises a laser processing head and an additive manufacturing system, wherein the additive manufacturing system is used to continuously convey additive manufacturing raw materials along the axial direction of the laser processing head; the laser processing head comprises a laser, a galvanometer system, a conical mirror and an annular reflector; the laser is used to generate parallel lasers, the conical mirror has a concave parabolic reflective surface, the galvanometer system is used to dynamically focus the parallel lasers to form working lasers, and reflect the working lasers to different positions of the concave parabolic reflective surface, the working lasers are reflected by the concave parabolic reflective surface to the annular reflector, and the annular reflector reflects the working lasers so that the light spot of the working lasers acts on the additive manufacturing raw materials, and the additive manufacturing raw materials are coaxially melted.

2. The laser rotary scanning coaxial melting device according to claim 1, It is characterized in that The galvanometer system includes a dynamic focusing mirror, an X-direction galvanometer and a Y-direction galvanometer; the dynamic focusing mirror is used to dynamically focus the working laser to form a working laser, the X-direction galvanometer can deflect along the X-direction and reflect the working laser, the Y-direction galvanometer can deflect along the Y-direction and receive the working laser reflected by the X-direction galvanometer, and reflect the working laser to the concave parabolic reflection surface.

3. The laser rotary scanning coaxial melting device according to claim 1, It is characterized in that The laser comprises a laser source, an optical fiber and a laser collimator. The optical fiber connects the laser source and the laser collimator. The laser source is used to generate laser light. The laser light is transmitted to the laser collimator along the optical fiber. The laser collimator collimates the laser light to form parallel laser light.

4. The laser rotary scanning coaxial melting device according to claim 1, It is characterized in that The laser processing head also includes a shell, the galvanometer system, the conical mirror and the annular reflector are all arranged in the shell, and the shell is provided with an arc-shaped channel for the working laser to pass through.

5. The laser rotary scanning coaxial melting device according to claim 1, It is characterized in that It also includes a robot arm, which is connected to the laser processing head.

6. The laser rotary scanning coaxial melting device according to claim 1, It is characterized in that The additive manufacturing raw material is wire and / or powder.

7. A laser rotary scanning coaxial melting method, It is characterized in that The laser rotary scanning coaxial melting device as described in claims 1 to 6 is used to coaxially melt the additive manufacturing raw material; the method comprises the following steps: The parallel laser is injected into the galvanometer system; The galvanometer system dynamically focuses the parallel laser to form a working laser, and reflects the working laser to the concave parabolic reflecting surface; The concave parabolic reflecting surface reflects the working laser to the annular reflecting mirror, and the annular reflecting mirror reflects the working laser so that the light spot of the working laser acts on the additive manufacturing raw material; The galvanometer system continuously deflects and reflects the working laser, and the light spots of the working laser are superimposed in the axial direction to form a cylindrical processing area.

8. The laser rotary scanning coaxial melting method according to claim 7, It is characterized in that The method also includes the steps of: slicing the digital model of the additively manufactured part in layers, forming a scanning track according to the width and overlap rate of a single melt track, and driving the laser processing head to move along the scanning track.

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