Transparent medium constraint still water assisted ultrafast laser cold processing technology of carbon fiber reinforced composite material

Abstract

The invention discloses a transparent medium constraint still water assisted ultrafast laser cold machining process for a carbon fiber reinforced composite material, and belongs to the technical field of ultrafast laser micro-nano manufacturing. According to the process, an isolation thin water layer protection interface is constructed in a processing area, so that interference of environmental atmosphere and impurities on the etching process is effectively isolated. According to the bead wetting behavior caused by the inherent hydrophobic characteristic of the carbon fiber reinforced composite material, uniform and controllable spreading of a water layer on the surface of the material is achieved in a breakthrough mode, and the geometric uniformity of the thickness of the thin water layer is guaranteed. Through the synergistic effect of the technical characteristics, the underwater ultrafast laser etching quality of the carbon fiber reinforced composite material is remarkably optimized.

Description

Technical Field

[0001] This invention belongs to the field of ultrafast laser micro-nano manufacturing technology, and particularly relates to a transparent medium-constrained hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials. Background Technology

[0002] Carbon fiber reinforced composites are composed of multiple layers of woven carbon fibers laminated within a resin matrix arranged in multiple orientations. With its superior combination of high specific strength, high specific modulus, strong corrosion resistance, and low density, this material has achieved significant breakthroughs in technological research and development and application promotion in recent years. It is now widely used in both military and civilian fields such as aerospace vehicles, automotive structural components, wind turbine blades, and sporting goods, becoming one of the key materials in high-end manufacturing.

[0003] In the processing technology system of carbon fiber reinforced composite materials, machining is currently the mainstream technology. The academic community has conducted continuous and in-depth research on core aspects such as material removal mechanisms, processing technology optimization, and tool structure design, resulting in relatively complete and systematic theoretical achievements. However, machining has two major problems: on the one hand, tools are prone to abnormal wear, leading to a significant increase in tool replacement frequency and directly driving up processing costs; on the other hand, fiber delamination is easily triggered during machining, severely damaging the surface integrity of the material and making it difficult to meet the processing requirements of high-precision components.

[0004] Laser processing technology, with its unique advantages of high precision, non-contact, and clean processing, can significantly improve the control of the morphological accuracy of processed components. As an advanced non-contact manufacturing method, it shows great application potential in the field of composite material processing and has become an important direction to replace traditional machining. Currently, research on laser processing technology for carbon fiber reinforced composite materials has become a cutting-edge hot topic in academia, and related explorations continue to advance.

[0005] It is worth noting that carbon fiber and epoxy resin matrices exhibit significant performance differences during laser processing: on the one hand, carbon fiber does not undergo a liquid phase transition under normal pressure, and its ablation threshold energy is an order of magnitude higher than that required for laser evaporation of the resin matrix; on the other hand, their material absorption rates and phase transition behaviors also differ significantly. These energy and performance differences directly lead to a series of systematic defects that are easily induced when laser-processing carbon fiber reinforced composites, including material delamination and cracking, end fiber expansion, internal fiber pull-out, and expansion of the heat-affected zone in the ablation area. Even with high energy density and rapid processing speed, enabling precise and rapid material cutting, these defects remain difficult to avoid, becoming a core bottleneck restricting the application of laser processing technology.

[0006] To address the shortcomings of traditional laser processing, ultrafast lasers, with their high-precision special processing characteristics, have been widely applied in the processing of difficult-to-machine materials such as ceramics, diamond, and carbon fiber composites. Their interaction mechanism with materials differs fundamentally from that of long-pulse lasers and continuous-wave lasers: ultrafast lasers have pulse widths in the picosecond to femtosecond range, allowing energy to be deposited in an extremely short time. Through a nonlinear absorption mechanism, the material is instantaneously converted into plasma, which then ablates the material through sputtering. During this process, plasma sputtering removes a significant amount of heat energy, preventing temperature accumulation in the processing area and causing a rapid decay, thus completely avoiding large-area thermal damage and large heat-affected zones, ultimately achieving high-quality processing. However, due to the multiphase structure of the materials themselves and the transient nature of laser thermal effects, microcracks and molten residues inevitably remain on the surface of materials processed by ultrafast lasers, directly affecting the product yield and processing quality of precision devices, necessitating further optimization.

[0007] To effectively suppress defects in ultrafast laser processing and improve material removal efficiency, liquid-assisted laser etching (LILE) technology is gradually becoming a novel alternative process for processing carbon fiber reinforced composite materials. This technology preferentially uses water as the auxiliary medium, primarily due to its high thermal conductivity, economic efficiency, and environmental friendliness. While the pure water-assisted laser etching process is relatively straightforward under static conditions, it faces two major technical bottlenecks: first, the inherent hydrophobicity of carbon fiber reinforced composite materials causes the water phase to exhibit bead-like wetting behavior on the material surface, preventing uniform spreading; second, the surface tension of water itself makes precise control of the static water layer thickness extremely difficult. Therefore, how to achieve precise control of the static water layer thickness while ensuring etching efficiency has become a core scientific problem urgently needing breakthroughs in the field of ultrafast laser micro / nano manufacturing, and is of great significance for promoting the development of high-precision processing technology for carbon fiber reinforced composite materials. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention proposes a transparent medium-constrained hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials. The aim is to ensure, without compromising processing efficiency, that the hydrostatic layer can be uniformly spread across the surface of the carbon fiber reinforced composite material and that the water layer is sufficiently thin and of uniform thickness. This reduces the heat-affected zone of laser etching, thereby improving etching quality and dimensional accuracy.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] One objective of this invention is to provide a transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials, comprising the following steps:

[0011] S1. Place the carbon fiber reinforced composite material to be processed into an ultrasonic cleaner for cleaning to make its surface smooth and free of contamination.

[0012] S2. Place the cleaned carbon fiber reinforced composite material flat into the graphite water storage tank and fix it in the processing position with a clamping and fixing device.

[0013] S3. Use a pipette to add pure water to the graphite water storage tank so that the pure water completely covers the surface of the carbon fiber reinforced composite material to form a static water layer.

[0014] S4. Press the ultra-clear glass onto the surface of the still water layer, ensuring that the lower surface of the ultra-clear glass is tightly bonded to the upper surface of the still water layer, and that there are no air bubbles.

[0015] S5. Place the graphite water tank containing carbon fiber reinforced composite material on the two-dimensional moving platform of the 532nm green picosecond laser; slowly move the two-dimensional moving platform using the processing software built into the 532nm green picosecond laser to move the graphite water tank containing carbon fiber reinforced composite material to the image center of the 532nm green picosecond laser.

[0016] S6. Import the pre-drawn CAD drawings and set the laser parameters through the built-in software of the 532nm green picosecond laser;

[0017] S7. Set the alignment point through the image center of the laser, turn on the optical shutter in the built-in processing software of the 532nm green picosecond laser, and perform underwater laser etching.

[0018] This invention utilizes the light transmittance and hydrophilicity of ultra-clear glass to effectively prevent the water layer surface from contacting the ambient atmosphere and impurities without affecting processing efficiency. Simultaneously, it ensures that the still water layer is uniformly spread on the surface of the carbon fiber reinforced composite material and guarantees that the still water layer is sufficiently thin and uniform. This effectively improves the etching quality of carbon fiber reinforced composite materials under still water layers, allowing for the etching of high-quality, complex patterns on the surface of carbon fiber reinforced composite materials using the method of this invention.

[0019] Furthermore, the thickness of the still water layer in step S4 is 1 to 5 mm.

[0020] Furthermore, the light transmittance of the ultra-white glass described in step S4 is higher than 90%.

[0021] Furthermore, in step S4, the size of the ultra-clear glass is larger than the coverage size of the still water layer.

[0022] Furthermore, the two-dimensional moving platform described in step S5 moves along the X-axis and Y-axis directions.

[0023] Furthermore, in step S6, the laser parameters used for etching the carbon fiber reinforced composite material under the still water layer are as follows: laser spot diameter 16 μm, average laser power 5-30W, scanning speed 20-100mm / s, repetition frequency 20-100kHz, number of scans 5-25, and wavelength 532nm.

[0024] Furthermore, during the laser etching process described in step S7, the overlap rate of the light spots on the scanning path is 60-95%.

[0025] The second objective of this invention is to provide a carbon fiber reinforced composite material product obtained by the above-described process.

[0026] The third objective of this invention is to provide an application of carbon fiber reinforced composite material products in aerospace vehicle structural components. This invention can effectively delay the generation of fatigue cracks at the edge of grooves in structural components and significantly extend the service life of structural components.

[0027] The fourth objective of this invention is to provide an application of carbon fiber reinforced composite material products in wind turbine blades. This invention can provide sharp and smooth grooves for laying metal guide nets in wind turbine blades, making the metal guide nets fit more tightly with the grooves.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] The method provided by this invention has low dependence on process parameters, a wide process window, and strong adaptability.

[0030] This invention demonstrates significant ease of operation and process stability. The overall process does not involve complex pretreatment steps and only requires routine cleaning to achieve continuous operation. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a process flow diagram of sample preparation in Examples 1-3 of the present invention;

[0033] Figure 2 Confocal 3D profile images of the samples prepared for Comparative Examples 1-3 (from left to right: Comparative Example 1, Comparative Example 2, and Comparative Example 3).

[0034] Figure 3 Confocal 3D profile images of the samples prepared in Examples 1-3 (from left to right: Example 1, Example 2, and Example 3);

[0035] Figure 4 Dotted-line diagrams of the groove widths of the samples prepared in Comparative Examples 1-3 and Examples 1-3;

[0036] Figure 5 Dotted-line diagrams of the groove depths of the samples prepared in Comparative Examples 1-3 and Examples 1-3;

[0037] Figure 6 The image shows the heat-affected zone dot-line diagrams of the samples prepared in Comparative Examples 1-3 and Examples 1-3. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0043] The process provided by this invention effectively isolates the etching process from environmental atmosphere and impurities by constructing an insulating thin water layer protective interface in the processing area. Addressing the bead-like wetting behavior caused by the inherent hydrophobic properties of carbon fiber reinforced composites, this process achieves a breakthrough by realizing uniform and controllable spreading of the water layer on the material surface, while ensuring the geometrical uniformity of the thin water layer thickness. The synergistic effect of these technical features significantly optimizes the underwater ultrafast laser etching quality of carbon fiber reinforced composites. The specific technical solution is as follows:

[0044] A transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials (see...) Figure 1 ), including the following steps:

[0045] S1. Place the carbon fiber reinforced composite material to be processed into an ultrasonic cleaner for cleaning to make its surface smooth and free of contamination.

[0046] S2. Place the cleaned carbon fiber reinforced composite material flat into the graphite water storage tank and fix it in the processing position with a clamping and fixing device.

[0047] S3. Use a pipette to add purified water to the graphite water storage tank so that the purified water completely covers the surface of the carbon fiber reinforced composite material, forming a still water layer with a thickness of 1 to 5 mm; for example, in the following preferred embodiment of the present invention, the thickness of the still water layer is 5 mm.

[0048] S4. Press ultra-clear glass with a light transmittance of over 90% onto the surface of the still water layer, ensuring that the lower surface of the ultra-clear glass is in close contact with the upper surface of the still water layer, and that there are no air bubbles; the size of the ultra-clear glass is larger than the coverage area of ​​the still water layer.

[0049] S5. Place the graphite water tank containing carbon fiber reinforced composite material on the two-dimensional moving platform of the 532nm green picosecond laser; slowly move the two-dimensional moving platform using the processing software built into the 532nm green picosecond laser, and move the graphite water tank containing carbon fiber reinforced composite material along the X-axis and Y-axis directions to the image center of the 532nm green picosecond laser.

[0050] S6. Import the pre-drawn CAD drawing and set the laser parameters through the built-in software of the 532nm green picosecond laser: laser spot diameter 16μm, average laser power 5-30W, scanning speed 20-100mm / s, repetition frequency 20-100kHz, number of scans 5-25, wavelength 532nm; for example, in the following preferred embodiment of the present invention, the average laser power is 15W, the scanning speed is 40mm / s, the repetition frequency is 60kHz, 80kHz or 100kHz, and the number of scans is 20.

[0051] S7. Set the alignment point through the image center of the laser, turn on the shutter in the built-in processing software of the 532nm green picosecond laser, and perform underwater laser etching; during the laser etching process, the overlap rate of the light spots on the scanning path is 60-95%.

[0052] By using the method of this invention, contact between the surface of the static water layer and the ambient atmosphere or impurities can be avoided. Simultaneously, it ensures that the static water layer is uniformly spread on the surface of the carbon fiber reinforced composite material and that the static water layer is sufficiently thin and uniform.

[0053] A carbon fiber reinforced composite material product can be obtained by using the above process.

[0054] The carbon fiber reinforced composite material products can be used in aerospace vehicle structural components.

[0055] The carbon fiber reinforced composite material products can be used in wind turbine blades.

[0056] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0057] All raw materials used in this invention were purchased from the market.

[0058] The technical solution of the present invention will be further illustrated by the following embodiments.

[0059] The following embodiments and comparative examples of this invention utilize an Amber NX GR-30S 30W green picosecond laser manufactured by Delong Corporation of China, with an output wavelength of 532nm and a repetition frequency adjustable from 1Hz to 2000kHz. This laser allows for underwater etching of carbon fiber reinforced composite materials through ultra-white glass with a transmittance of over 90% and still water layers. The carbon fiber reinforced composite material used is T300 manufactured by Toray Industries, Inc. of Japan.

[0060] Example 1

[0061] A transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials (see...) Figure 1 ), including the following steps:

[0062] S1. Place the carbon fiber reinforced composite material to be processed into an ultrasonic cleaner for cleaning to make its surface smooth and free of contamination.

[0063] S2. Place the cleaned carbon fiber reinforced composite material flat into the graphite water storage tank and fix it in the processing position with a clamping and fixing device.

[0064] S3. Use a pipette to add pure water to the graphite water storage tank so that the pure water completely covers the surface of the carbon fiber reinforced composite material, forming a still water layer with a thickness of 5mm.

[0065] S4. Press ultra-clear glass with a light transmittance of over 90% onto the surface of the still water layer, ensuring that the lower surface of the ultra-clear glass is in close contact with the upper surface of the still water layer, and that there are no air bubbles; the size of the ultra-clear glass is larger than the coverage area of ​​the still water layer.

[0066] S5. Place the graphite water tank containing carbon fiber reinforced composite material on the two-dimensional moving platform of the 532nm green picosecond laser; slowly move the two-dimensional moving platform using the processing software built into the 532nm green picosecond laser, and move the graphite water tank containing carbon fiber reinforced composite material along the X-axis and Y-axis directions to the image center of the 532nm green picosecond laser.

[0067] S6. Import the pre-drawn CAD drawing and set the laser parameters through the built-in software of the 532nm green picosecond laser: laser spot diameter 16μm, average laser power 15W, scanning speed 40mm / s, repetition frequency 60kHz, number of scans 20, wavelength 532nm.

[0068] S7. Set the alignment point through the image center of the laser, turn on the shutter in the built-in processing software of the 532nm green picosecond laser, and perform underwater laser etching; during the laser etching process, the overlap rate of the light spots on the scanning path is 95.83%.

[0069] Example 2

[0070] Same as Example 1, except that the laser repetition frequency in step S6 is 80kHz and the spot overlap rate is 96.88%.

[0071] Example 3

[0072] Same as Example 1, except that the laser repetition frequency in step S6 is 100kHz and the spot overlap rate is 97.50%.

[0073] Comparative Example 1

[0074] Same as Example 1, except that step S4 is not performed.

[0075] Comparative Example 2

[0076] Same as Example 2, except that step S4 is not performed.

[0077] Comparative Example 3

[0078] Same as Example 3, except that step S4 is not performed.

[0079] The samples obtained from Comparative Examples 1-3 and Examples 1-3 were subjected to the following quality observations:

[0080] KEYENCE VK-X series confocal microscope: Place the sample on the movable stage of the confocal microscope, observe it using a 20x objective lens, and take a three-dimensional contour image of the sample. Analyze the depth, width, and heat-affected zone width of the etched trenches using analysis software.

[0081] Figure 2 Confocal 3D profile images of the samples prepared for Comparative Examples 1-3 (from left to right: Comparative Example 1, Comparative Example 2, and Comparative Example 3), from... Figure 2 It can be seen that, in Comparative Example 1, at a lower repetition frequency, some molten residue from the melted resin appeared in the trench. Comparative Example 3, due to the use of a higher repetition frequency, resulted in a larger heat-affected zone on its surface, and also produced larger molten residue in the trench.

[0082] Figure 3 The images show confocal 3D profiles of the samples prepared in Examples 1-3 (from left to right: Example 1, Example 2, and Example 3). Figure 3 It can be seen that the grooves in Examples 1-3 are relatively complete, without the small pieces of molten residue in Comparative Example 1 or the large pieces of molten residue and large heat-affected zone in Comparative Example 3.

[0083] Figure 4 The image shows a dotted line graph of the groove width of the samples prepared in Comparative Examples 1-3 and Examples 1-3. Figure 4 It can be seen that the groove widths of Comparative Examples 1-3 are all greater than those of Examples 1-3. The groove widths of both Comparative Examples 1-3 and Examples 1-3 increase with increasing repetition frequency. However, the increase in groove width in Examples 1-3 is more gradual.

[0084] Figure 5 The image shows a dotted line plot of the groove depth of the samples prepared in Comparative Examples 1-3 and Examples 1-3. Figure 5 It can be seen that the trench depths of Comparative Examples 1-3 are all greater than those of Examples 1-3. At lower repetition frequencies, the trench depths of the two processes—the still water layer and the ultra-clear glass sheet covering—are similar. The trench depths of both Comparative Examples 1-3 and Examples 1-3 increase with increasing repetition frequency. However, the increase in trench depth in Examples 1-3 is more gradual.

[0085] Figure 6 The heat-affected zone dot plots are shown for the samples prepared in Comparative Examples 1-3 and Examples 1-3. Figure 6 It can be seen that the heat-affected zones of Comparative Examples 1-3 and Examples 1-3 both increase with the increase of repetition frequency, with Comparative Example 3 exhibiting a larger heat-affected zone. However, the increase in the heat-affected zone of Examples 1-3 is relatively smooth.

[0086] In summary, although this invention reduces the etching depth and width of some trenches, the introduction of ultra-white glass sheets can effectively reduce the heat-affected zone of carbon fiber composite materials, and significantly improve the overall processing quality of liquid-assisted ultrafast laser etching of carbon fiber composite materials at a high repetition frequency.

[0087] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials, characterized in that, Includes the following steps: S1. Place the carbon fiber reinforced composite material to be processed into an ultrasonic cleaner for cleaning to make its surface smooth and free of contamination. S2. Place the cleaned carbon fiber reinforced composite material flat into the graphite water storage tank and fix it in the processing position with a clamping and fixing device. S3. Add pure water to the graphite water storage tank so that the pure water completely covers the surface of the carbon fiber reinforced composite material to form a static water layer. S4. Press the ultra-clear glass onto the surface of the still water layer, ensuring that the lower surface of the ultra-clear glass is tightly bonded to the upper surface of the still water layer, and that there are no air bubbles. S5. Place the graphite water tank containing carbon fiber reinforced composite material on the two-dimensional moving platform of the 532nm green picosecond laser. S6. Import the pre-drawn CAD drawings and set the laser parameters through the built-in software of the 532nm green picosecond laser; S7. Set the alignment point through the image center of the laser, open the optical shutter, and perform underwater laser etching.

2. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, The thickness of the still water layer in step S4 is 1 to 5 mm.

3. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, The light transmittance of the ultra-white glass described in step S4 is higher than 90%.

4. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, In step S4, the size of the ultra-clear glass is larger than the coverage area of ​​the still water layer.

5. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, The two-dimensional moving platform described in step S5 moves along the X-axis and Y-axis directions.

6. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, The laser parameters mentioned in step S6 are: laser spot diameter 16μm, average laser power 15W, scanning speed 40mm / s, repetition frequency 60~100kHz, number of scans 20, and wavelength 532nm.

7. The transparent medium-confined hydrostatic-assisted ultrafast laser cold processing technology for carbon fiber reinforced composite materials according to claim 1, characterized in that, During the laser etching process described in step S7, the overlap rate of the light spots on the scanning path is 60-95%.

8. A carbon fiber reinforced composite material product obtained by the process described in any one of claims 1-7.

9. The application of a carbon fiber reinforced composite material article as described in claim 8 in aerospace vehicle structural components.

10. The application of a carbon fiber reinforced composite material article as described in claim 8 in a wind turbine blade.

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