A laser polishing method and laser polishing apparatus

Abstract

This invention discloses a laser polishing method and apparatus, relating to the field of aero-engine blade processing technology. The laser polishing method is used for laser polishing engine blades, including a preheating step, a laser polishing step, a heat preservation step, and a cooling step. The preheating step heats the blade to a first temperature; the laser polishing step polishes the surface of the blade using a laser; the heat preservation step maintains the blade at a second temperature; and the cooling step cools the blade to a third temperature. This laser polishing method can reduce or eliminate the remelted layer on the blade surface, improving the blade's performance.

Description

Technical Field

[0001] This invention relates to the field of aero-engine blade processing technology, and in particular to a laser polishing method and laser polishing apparatus. Background Technology

[0002] Aero engines contain a large number of blades, which are core components. The quality of the blades directly affects the engine's performance and lifespan. Blade polishing is a crucial process for improving blade lifespan, fatigue strength, and aerodynamic performance. Currently, the polishing of most aero engine blades relies almost entirely on manual grinding, which can easily lead to unstable quality, poor blade precision, and an inability to meet the processing requirements of modern high-performance aero engine blades.

[0003] Laser polishing, as a novel surface polishing technology, is very suitable for polishing irregular curved surfaces such as blades. However, as a thermal processing technology, laser polishing leaves a remelted layer on the surface after polishing. In complex and harsh environments, the remelted layer becomes a weak area, affecting the performance of the blade and greatly limiting the application of laser polishing on aerospace blades.

[0004] To address the aforementioned problems, it is necessary to develop a laser polishing method and a laser polishing device to solve these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a laser polishing method and a laser polishing apparatus that can reduce or eliminate the remelted layer on the blade surface and improve the performance of the blade.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A laser polishing method for laser polishing blades of an aero-engine includes:

[0008] In the preheating step, the blades are heated to a first temperature;

[0009] The laser polishing step involves using a laser to polish the surface of the blade.

[0010] The heat preservation step involves heat preservation of the blades at a second temperature.

[0011] The cooling step cools the temperature of the blade to a third temperature.

[0012] Preferably, the preheating step is performed by placing the blade into a preheating station, and multiple preheating stations are provided, with the blade sequentially entering multiple preheating stations.

[0013] Preferably, the heat preservation step is carried out by placing the blade into a heat preservation station, and multiple heat preservation stations are provided, with the blade entering multiple heat preservation stations in sequence.

[0014] Preferably, before the preheating step, a feeding step is included, which includes fixing the blades and initially positioning the blades.

[0015] Preferably, in the laser polishing step, the edge or surface of the blade is repositioned before polishing the surface of the blade.

[0016] Preferably, in the cooling step, the blades are cooled by air cooling.

[0017] A laser polishing apparatus is provided, which can perform laser polishing on engine blades using the laser polishing method described above. The laser polishing apparatus includes a machine base, on which a support platform is rotatably mounted. A plurality of clamping components are spaced apart along the circumferential direction on the support platform. A preheating component, a laser polishing component, a heat preservation component, and a cooling component are sequentially arranged around the support platform along the rotation direction of the support platform.

[0018] Preferably, multiple preheating components and multiple heat insulation components are arranged at continuous intervals.

[0019] Preferably, the preheating component includes a liftable heating element, which has a heating groove adapted to the shape of the blade. When the heating element rises, the blade can enter the heating groove for heating.

[0020] Preferably, the laser polishing assembly includes:

[0021] A laser emitter capable of emitting a laser to laser polish the blade;

[0022] A positioning probe is slidably disposed on the laser emitter in a vertical direction, and the positioning probe can abut against the blade to locate the position of the laser emitter.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a laser polishing method and a laser polishing apparatus. In this laser polishing method, the blade is preheated before laser polishing and then kept warm and cooled after laser polishing. Preheating increases the blade's temperature, thereby increasing the activity between blade molecules, reducing the energy requirement for laser polishing, controlling the amount of remelted metal during laser polishing, and minimizing the remelted layer. Keeping warm allows for solution treatment of the blade after laser polishing, absorbing the remelted layer and achieving laser polishing without a remelted layer.

[0025] This laser polishing method can reduce or eliminate the remelted layer on the blade surface, thereby improving the blade's performance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the laser polishing device provided by the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of the support platform, clamping assembly and robotic arm provided by the present invention;

[0028] Figure 3 This is a metallographic image of a blade directly laser-polished according to the present invention.

[0029] Figure 4 This is a metallographic image of the blade provided by the present invention after polishing using the laser polishing device;

[0030] Figure 5 This is a schematic diagram of the preheating component provided by the present invention;

[0031] Figure 6 This is a schematic diagram of the structure of the thermal insulation component provided by the present invention;

[0032] Figure 7 This is a schematic diagram of the cooling assembly provided by the present invention;

[0033] Figure 8 This is a schematic diagram of the structure of the laser polishing component provided by the present invention.

[0034] In the picture:

[0035] 100. Blade; 101. Remelted layer;

[0036] 1. Machine base; 2. Support platform; 3. Preheating assembly; 4. Laser polishing assembly; 5. Insulation assembly; 6. Cooling assembly; 7. Clamping assembly; 8. Robotic arm;

[0037] 31. Heating element; 41. Laser emitter; 42. Positioning probe; 51. Insulation cover; 52. Heating tube; 53. Thermocouple; 61. Insulation box; 62. Impeller; 63. Heat sink; 71. Telescopic cylinder; 72. Rotary cylinder; 73. Gripper;

[0038] 311. Heating tank; 411. Optical fiber; 412. Collimator; 413. Cooling component; 414. Beam expander; 415. Three-dimensional galvanometer; 416. Field lens; 417. Reflector; 418. Lens. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0041] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0042] Unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" of a second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] Aero engines have a large number of blades, which are the core components of the engine. The quality of the blades directly affects the engine's performance and lifespan. Blade polishing is an important process for improving blade service life, fatigue strength, and aerodynamic performance.

[0045] The blades of aero engines have complex structures. In addition, since the blade materials are generally titanium alloys or high-temperature alloys, which have high hardness, they also cause greater wear and tear on the mechanical polishing head, resulting in high polishing costs. Therefore, the application of automatic mechanical polishing in blade polishing is relatively limited.

[0046] Laser polishing, as a novel surface polishing technology, offers advantages such as non-contact operation and ease of automation, making it ideal for polishing irregular, curved surfaces like blades. However, as a thermal processing technology, lasers utilize a high-energy focused laser beam to melt the material surface, achieving polishing through the self-flowing molten metal. This process leaves a remelted layer on the surface after polishing. The crystal structure of this remelted layer is altered, and in complex and harsh environments, it can become a weak point, affecting blade performance and significantly limiting the application of laser polishing on aerospace blades.

[0047] To address the above problems, this embodiment provides a laser polishing method, which includes:

[0048] The preheating step involves heating the blade 100 to the first temperature;

[0049] Preheating can increase the temperature of the blade 100 and increase the activity between the molecules of the blade 100, thereby reducing the energy requirements during laser polishing. In other words, a low-power laser beam can be used during laser polishing, thereby controlling the amount of remelted metal during laser polishing and reducing the remelted layer 101 of laser polishing.

[0050] The laser polishing step involves polishing the surface of the blade 100 using a laser.

[0051] The insulation process involves insulating the blade 100 at a temperature equal to the second temperature.

[0052] It is understandable that even if the preheating step can significantly reduce the remelted layer 101, the remelted layer 101 will still be generated. The heat preservation process can perform solid solution treatment on the laser-polished blade 100, absorbing the remelted layer 101, thereby achieving laser polishing of the blade 100 without the remelted layer 101.

[0053] The cooling step cools the temperature of the blade 100 to the third temperature.

[0054] After the blade 100 is insulated, its temperature is high. The cooling component 6 is needed to lower the temperature of the blade 100 in order to complete the unloading operation. After the blade 100 is transferred to the material box, its temperature gradually drops to the ambient temperature.

[0055] The specific ranges of the first and second temperatures need to be selected according to the type of blade 100. In practical applications, the first temperature is 120-360℃. The purpose of the preheating step is to improve the molecular activity of the blade 100, so the temperature does not need to be too high. The second temperature is 550-1100℃. The purpose of the heat preservation step is to absorb the remelted layer 101, so the second temperature needs to be able to cause a phase transition in the crystal structure of the blade 100, hence the temperature range is relatively high.

[0056] Understandably, the cooling step is to cool down the blade 100 so that it can be fed into the machine, so the third temperature should not be too high, and its range is 20-60℃.

[0057] Taking the titanium alloy blade 100 as an example, the first temperature is 280-320℃, the second temperature is 950-1050℃, and the third temperature is 20-60℃.

[0058] To efficiently complete the laser polishing of the blade 100, this embodiment also provides a laser polishing apparatus. For example... Figures 1-4 As shown, the laser polishing device includes a machine base 1, a support platform 2 is rotatably mounted on the machine base 1, and a number of clamping components 7 are arranged at intervals along the circumference of the support platform 2. The machine base 1 is arranged around the support platform 2 along the rotation direction of the support platform 2, and a preheating component 3, a laser polishing component 4, a heat preservation component 5 and a cooling component 6 are arranged in sequence.

[0059] The polishing process of this laser polishing device involves preheating the blade 100 before laser polishing and then maintaining and cooling the blade 100 after laser polishing. It possesses the advantages of high efficiency, high processing quality, and good consistency inherent in laser polishing. Furthermore, it is a non-contact polishing process, eliminating polishing dead angles and not altering the dimensions of the workpiece during polishing. Figure 3 and Figure 4 As shown, the remelted layer 101 of the blade 100 has disappeared after being treated by the laser polishing device. This laser polishing device can reduce or eliminate the remelted layer 101 on the surface of the blade 100, with good polishing quality, high efficiency, and good consistency, thus improving the performance of the blade 100.

[0060] Each clamping component 7 of the laser polishing device clamps a blade 100. As the support table 2 rotates, the blade 100 sequentially passes through the preheating component 3, the laser polishing component 4, the heat preservation component 5, and the cooling component 6. It is understood that the key step of this laser polishing device is laser polishing; therefore, to improve efficiency, the support table 2 rotates once every reference time interval, using the time the blade 100 spends in the laser polishing component 4 as the reference time, moving the blade 100 to the next processing step.

[0061] However, this leads to a problem: insufficient preheating and heat preservation time, resulting in insufficient temperature of blade 100 before laser polishing or insufficient heat preservation time after laser polishing, causing a large amount of remelted layer 101 to remain on the surface of blade 100.

[0062] To address this issue, the preheating step involves placing the blade 100 into multiple preheating stations, with the blade 100 sequentially entering each station to extend the preheating time. Each preheating station is a preheating assembly 3. Since the support platform 2 simultaneously holds multiple blades 100 via multiple clamping components 7, and to improve efficiency, after laser polishing of the blade 100, the support platform 2 needs to rotate to move the next blade 100 to the laser polishing assembly 4. This results in a short dwell time for the blade 100 at each process. Multiple preheating assemblies 3 ensure that the blade 100 passes through multiple preheating assemblies 3 sequentially before laser polishing, effectively extending the preheating time and guaranteeing that the blade 100 reaches the preheating temperature. This ensures processing efficiency and reduces or eliminates the remelted layer 101 on the blade 100 surface, thereby guaranteeing the performance of the blade 100.

[0063] Understandably, the heat preservation step is performed by placing the blade 100 into multiple heat preservation stations. The blade 100 enters multiple heat preservation stations sequentially to extend the heat preservation time. The heat preservation station is the heat preservation component 5, which works on the same principle as the preheating component 3. Multiple heat preservation components 5 cause the laser-polished blade 100 to pass through multiple heat preservation components 5 sequentially, thereby extending the heat preservation time and ensuring that the lattice structure of the remelted layer 101 is transformed. This ensures both processing efficiency and reduces or eliminates the remelted layer 101 on the surface of the blade 100, thus guaranteeing the performance of the blade 100.

[0064] Preferably, before the preheating step, a loading step is included, which includes fixing the blade 100 and initially positioning the blade 100. In the loading step, the robot moves the blade 100 to the clamping assembly 7 and clamps and fixes the blade 100 by the clamping assembly 7 to complete the loading step.

[0065] Preferably, in the laser polishing step, the edge or surface of the blade 100 is repositioned before polishing the surface of the blade 100. It is understood that during the rotation of the support platform 2, the blade 100 may not accurately stop at the laser polishing position due to vibration of the support platform 2 or its own precision issues. The laser polishing assembly 4 includes a positioning probe. When the blade 100 moves to the laser polishing assembly 4 and comes into contact with the positioning probe 42, the secondary positioning is completed. At this point, the position of the blade 100 is the laser polishing position, thereby improving the accuracy of the laser polishing.

[0066] Preferably, the cooling step utilizes air cooling to cool the blade 100. It is understood that the cooling rate of the blade 100 should not be too slow, otherwise the surface of the blade 100 will easily be oxidized; and the cooling rate of the blade 100 should not be too fast, otherwise a hard and brittle structure will easily form on the surface of the blade 100, which will negatively affect the performance of the blade 100. Therefore, air cooling can cool the blade 100 at a suitable cooling rate.

[0067] To enable laser polishing of the blade 100 using the aforementioned laser polishing method, multiple preheating components 3 and multiple heat preservation components 5 are continuously spaced apart. As the blade 100 rotates with the support platform 2, it passes through multiple preheating components 3 or heat preservation components 5 in sequence, thereby extending the preheating and heat preservation time. This ensures processing efficiency and reduces or eliminates the remelted layer 101 on the surface of the blade 100, thus guaranteeing the performance of the blade 100.

[0068] like Figure 2 As shown, the clamping assembly 7 includes a rotary cylinder 72 and a gripper 73. The gripper 73 is disposed on the rotation shaft of the rotary cylinder 72 and is used to clamp and fix the blade 100. The gripper 73 can clamp the blade 100 to ensure the stability of the blade 100, while the rotary cylinder 72 can drive the gripper 73 to rotate through the rotation shaft, thereby enabling the blade 100 to rotate 180°. When the blade 100 is laser polished under the laser polishing assembly 4, after polishing on one side is completed, it can be flipped 180° for laser polishing on the other side, without the need for the laser polishing assembly 4 to rotate under the blade 100, which saves space and simplifies the mechanism.

[0069] Preferably, the clamping assembly 7 further includes a telescopic cylinder 71, which is fixedly mounted on the support platform 2, and a rotary cylinder 72 is mounted on the piston rod of the telescopic cylinder 71. Since the preheating assembly 3, laser polishing assembly 4, heat preservation assembly 5, and cooling assembly 6 are all located on the outer periphery of the support platform 2, after the support platform 2 finishes rotating, the piston rod of the telescopic cylinder 71 can drive the blade 100 into the corresponding process. When the processing is complete, the piston rod retracts, causing the blade 100 to disengage from the corresponding process, and then the support platform 2 continues to rotate. The telescopic cylinder 71 can prevent the blade 100 from colliding with the preheating assembly 3, laser polishing assembly 4, heat preservation assembly 5, and cooling assembly 6.

[0070] Preferably, the support platform 2 is equipped with a robotic arm 8, which can move the blade 100 to the gripper 73 and be clamped and fixed by the gripper 73. The robotic arm 8 is a six-axis robotic arm, which can pick up the blade 100 at the loading point and move it to the gripper 73 for clamping and fixing, thereby improving the automation level of the laser polishing device.

[0071] Among them, the robotic arm 8 is existing technology and is not limited to a six-axis robotic arm. It is sufficient as long as it can move the blade 100 to the gripper 73.

[0072] like Figure 5 As shown, the preheating assembly 3 includes a liftable heating element 31. The heating element 31 has a heating groove 311 that matches the shape of the blade 100. When the heating element 31 rises, the blade 100 can enter the heating groove 311 for heating. When the blade 100 rotates with the support platform 2 to the preheating assembly 3, it enters the preheating assembly 3 under the drive of the telescopic cylinder 71. At this time, the heating element 31 of the preheating assembly 3 moves upward, and the blade 100 enters the heating groove 311 and abuts against the inner wall of the heating groove 311, thereby greatly improving the heating speed of the blade 100 and thus improving the heating efficiency. This also allows for the minimization of the number of preheating assemblies 3, simplifying the structure.

[0073] like Figure 6 As shown, the insulation component 5 includes an insulation cover 51 and a heating pipe 52 disposed within the insulation cover 51. The blade 100 can extend into the insulation cover 51 and be heated and insulated by the heating pipe 52. When the blade 100 enters the insulation cover 51, the heating pipe 52 inside the insulation cover 51 begins to heat, raising the temperature inside the insulation cover 51, thereby insulating the blade 100. During the insulation process, the lattice of the remelted layer 101 on the surface of the blade 100 begins to undergo solid solution, thereby changing to the same lattice structure as other parts of the blade 100, thus improving the performance of the blade 100.

[0074] When the insulation component 5 insulates the blade 100, the insulation cover 51 is in a vacuum state. It is understandable that the insulation process takes a long time, and the blade 100 is easily oxidized. Therefore, a vacuum state is required to protect the blade 100 and prevent the surface of the blade 100 from being oxidized, which would affect its performance.

[0075] Specifically, the heating tubes 52 are arranged in a circular pattern, and the blades 100 are located in the middle of the heating tubes 52 during the heat preservation process. The circular arrangement of the heating tubes 52 can improve the heating rate inside the heat preservation cover 51, while ensuring the temperature uniformity of the blades 100 during the heat preservation process.

[0076] The insulation component 5 also includes a temperature controller and a thermocouple 53. The thermocouple 53 can detect the temperature inside the insulation cover 51 and feed it back to the temperature controller. The temperature controller can control the heating power of the heating tube 52 according to the set temperature to ensure that the temperature inside the insulation cover 51 is the same as the set temperature.

[0077] like Figure 7As shown, the cooling assembly 6 includes an insulation box 61, an impeller 62, and a heat sink 63. The impeller 62 is rotatably disposed inside the insulation box 61, and the heat sink 63 is disposed around the impeller 62. When the blades 100, after the insulation is completed, rotate with the support platform 2 to the cooling assembly 6, the blades 100 enter the center of the impeller 62. At this time, the impeller 62 rotates, and the heat from the blades 100 is carried away by the airflow and blown towards the heat sink 63. The heat sink 63 can transfer the heat to the outside of the insulation box 61 to achieve cooling of the blades 100.

[0078] like Figure 8 As shown, the laser polishing assembly 4 includes a laser emitter 41 and a positioning probe 42. The laser emitter 41 emits a laser to polish the blade 100. The positioning probe 42 is slidably mounted on the laser emitter 41 in a vertical direction and can abut against the blade 100 to position the laser emitter 41. The positioning probe 42 moves downwards. When the blade 100 rotates to the laser polishing assembly 4 and abuts against the positioning probe 42, the support platform 2 stops rotating. At this point, the position of the blade 100 is the polishing position. The laser emitter 41 scans and polishes the blade 100 according to a preset processing trajectory. After polishing one side, the blade 100 rotates and polishes the other side of the blade 100. After laser polishing is completed, the positioning probe 42 moves upwards to avoid the blade 100, allowing the blade 100 to rotate with the support platform 2 to the next process.

[0079] The laser emitter 41 includes an optical fiber 411, a collimator 412, a cooling element 413, a beam expander 414, a lens 418, a three-dimensional galvanometer 415, and a field lens 416. The laser beam is output from the optical fiber 411, collimated by the collimator 412, and then enters the beam expander 414 along its axis. The beam expander 414 expands and collimates the laser beam a second time. The beam is then shaped by the lens 418, transforming the Gaussian energy distribution of the laser beam into a flat-top distribution. The shaped laser beam then enters the three-dimensional galvanometer 415 and is focused onto the surface of the blade 100 by the field lens 416 for polishing.

[0080] In this embodiment, two reflectors 417 are arranged before and after the beam expander 414 to change the propagation direction of the laser beam, thereby facilitating the flexible placement of components within the laser emitter 41. To improve the laser beam shaping effect, the laser emitter 41 is equipped with two lenses 418, which are spaced apart between the two reflectors 417 after the beam expander 414.

[0081] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A laser polishing method, wherein a laser polishing device is used to laser polish blades (100) of an aero-engine, characterized in that, The laser polishing device includes a machine base (1), on which a support platform (2) is rotatably mounted. The support platform (2) is provided with a plurality of clamping components (7) spaced apart along the circumference. The machine base (1) is provided with a preheating component (3), a laser polishing component (4), a heat preservation component (5), and a cooling component (6) in sequence around the support platform (2) along the rotation direction of the support platform (2). The preheating components (3) are arranged in multiple continuous intervals, and the heat preservation components (5) are arranged in multiple continuous intervals; The preheating component (3) includes a liftable heating element (31), which has a heating groove (311) adapted to the shape of the blade (100). When the heating element (31) rises, the blade (100) can enter the heating groove (311) for heating. The laser polishing method includes: In the preheating step, the blade (100) is heated to a first temperature; preheating can increase the temperature of the blade (100), increase the activity between blade molecules, reduce the energy requirements during laser polishing, and control the amount of remelted metal during laser polishing; The laser polishing step involves polishing the surface of the blade (100) using a laser. The heat preservation step involves heat preservation of the blade (100) at a second temperature. Heat preservation enables the blade (100) to undergo solid solution treatment after laser polishing, absorbing the remelted layer and thus achieving laser polishing of the blade (100) without a remelted layer. The cooling step cools the temperature of the blade (100) to a third temperature; The preheating step is carried out by placing the blade (100) into a preheating station. There are multiple preheating stations, and the blade (100) enters multiple preheating stations in sequence. The heat preservation step is carried out by placing the blade (100) into the heat preservation station. There are multiple heat preservation stations, and the blade (100) enters multiple heat preservation stations in sequence.

2. The laser polishing method according to claim 1, characterized in that, Before the preheating step, there is also a feeding step, which includes fixing the blade (100) and initially positioning the blade (100).

3. The laser polishing method according to claim 1, characterized in that, In the laser polishing step, before polishing the surface of the blade (100), the edge or surface of the blade (100) is repositioned.

4. The laser polishing method according to claim 1, characterized in that, In the cooling step, the blade (100) is cooled by air cooling.

5. The laser polishing method according to claim 1, characterized in that, The laser polishing assembly (4) includes: A laser emitter (41) is capable of emitting a laser to perform laser polishing on the blade (100); A positioning probe (42) is slidably disposed on the laser emitter (41) in the vertical direction. The positioning probe (42) can abut against the blade (100) to position the laser emitter (41).

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