A method for CO2 continuous laser cutting of CFRP material

Abstract

This invention discloses a method for CO2 continuous laser cutting of CFRP material. The method employs a CO2 continuous laser engraving and cutting system to cut CFRP material. After adjusting the corresponding working parameters, a portion of the CFRP material to be cut is taken as a sample, and a rectangle is obtained through trial cutting. The diameters of the pits generated by the spot laser are measured horizontally and vertically twice, and the average diameter is calculated. Simultaneously, the continuous laser power density is calculated, and the height difference between the four corners and the center of the rectangle is measured to obtain the surface fluctuation value (Fv). Different scanning speeds, number of consecutive processing cycles, and Z-axis scale values ​​are selected, and trial cutting is repeated on the sample. When the measured Fv is at its minimum value, the thermal damage to the material is minimized. The scanning speed, number of consecutive processing cycles, and Z-axis scale value at this minimum value are used as the working parameters for cutting the CFRP material. This invention effectively controls the thermal damage to the CFRP material during processing and improves the processing effect of laser-processed CFRP material.

Description

Technical Field

[0001] This invention belongs to the field of carbon fiber plastic processing technology, specifically relating to a method for CO2 continuous laser cutting of CFRP material. Background Technology

[0002] The aerospace and new energy fields not only require high-strength, corrosion-resistant, and high-temperature-resistant materials, but also lightweight and environmentally friendly ones. The emergence of carbon fiber reinforced plastics (CFRP) plays a crucial role in the manufacturing processes of aerospace, satellite communications, and new energy vehicles. The production process typically involves drilling, partially cutting, and etching CFRP materials; however, due to the high strength and anisotropic properties of CFRP, its processing methods face even higher demands. Currently, mechanical processing is the primary method for machining CFRP. However, excessive cutting edge wear and frequent tool replacement during machining lead to high costs and low processing quality, easily resulting in defects such as burrs and delamination. High-pressure abrasive waterjet machining offers advantages such as cleanliness, environmental friendliness, safety, low cost, and concentrated energy, but the surface quality is relatively low. Electrical discharge machining (EDM) is a thermal processing method, resulting in a large heat-affected zone (HAZ). Laser processing offers high precision, non-contact operation, high efficiency, and low cost. However, because CFRP is an anisotropic material with significant differences in thermodynamic properties between the matrix and reinforcing phases, thermal damage such as delamination, end expansion, HAZ, and fiber pull-out can occur during processing. Ultrashort pulse lasers, known as "cold processing" due to their short processing time, still result in HAZs when machining CFRP. Improper frequency settings can lead to significant heat accumulation, and the HAZ varies depending on the layup of the composite material. Therefore, controlling thermal damage to CFRP during processing is currently a hot topic and a challenge in laser-processed CFRP materials. Summary of the Invention

[0003] To address the aforementioned shortcomings, this invention discloses a method for CO2 continuous laser cutting of CFRP materials, which effectively controls thermal damage to CFRP materials during processing, improves the processing effect of laser-processed CFRP materials, and is conducive to the promotion and application of laser-processed CFRP materials methods.

[0004] This invention is achieved using the following technical solution:

[0005] A method for CO2 continuous laser cutting of CFRP material, comprising the following steps:

[0006] (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting.

[0007] (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. For every 0.5mm or 1mm increase in distance D, perform spot firing on the sample once. Measure the diameter of the pit generated by spot firing twice, both horizontally and vertically, and calculate the average diameter according to Formula I. At the same time, calculate the continuous laser power density according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value.

[0008] Due to the anisotropy of the material, the pits generated by spot firing are irregularly circular. Therefore, the diameter of each pit is measured twice, horizontally and vertically, and the average diameter is calculated. Since the spot firing time is short, the pits only effectively ablate the resin layer on the material surface. Therefore, only the average diameter is compared. When the distance D between the focusing lens and the sample is different, the average diameter of the pits formed by the laser on the material will also be different. When the average diameter of the pit reaches the minimum value, the average diameter of the pit is approximately the diameter of the laser spot. At this time, the laser focus is exactly on the material, that is, the defocus is approximately 0. At this time, the continuous laser power density also reaches the maximum, which concentrates the energy input and improves the laser effect.

[0009] Then, a test cut is performed on the sample. A rectangle is cut out on the sample, the center of the cut rectangle is marked, and the height difference between the four corners of the rectangle and the center of the rectangle is measured. The surface fluctuation value of the rectangle is calculated according to Formula III.

[0010] Formula I is D avg = (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm.

[0011] Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm.

[0012] Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; HDif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm.

[0013] (3) Select different scanning speeds and number of consecutive processing times, and repeat the trial cutting on the sample. When the measured Fv is the minimum value, the thermal damage of the material is the lowest. Use the scanning speed and number of consecutive processing times at this time as working parameters to cut the CFRP material to be cut.

[0014] During the process of cutting a rectangular area on the sample, energy cuts through the surface resin and is transmitted to the internal carbon fiber and conducted. After processing, the surface resin within the rectangular area is heated by the transmitted heat, causing it to expand or a small part of it to reach its melting point, resulting in unevenness. This creates a height difference between the four corners of the rectangle and the center point. This invention characterizes the unevenness of the surface resin within the rectangular area by measuring the average of the absolute values ​​of these four differences (rectangular surface fluctuation value), indicating the transmission and accumulation of energy on the processed surface. This allows for an effective assessment of the degree of thermal damage. Repeated cutting tests are conducted. When the measured rectangular surface fluctuation value (Fv) is at its minimum, it indicates that the energy accumulation is relatively small when cutting under the corresponding working conditions, and the thermal damage to the material is also relatively small.

[0015] Furthermore, the scanning speed ranges from 3 to 7 mm / s, and the number of continuous processing cycles ranges from 1 to 20.

[0016] Furthermore, the scanning speed is any one of 3mm / s, 4mm / s, 5mm / s, 6mm / s, and 7mm / s.

[0017] Furthermore, the number of consecutive processing cycles is any one of 1, 5, 10, 15, and 20.

[0018] Furthermore, the distance D ranges from 15mm to 27mm, preferably from 23mm to 25mm.

[0019] Compared with existing technologies, this technical solution has the following advantages:

[0020] Based on the characteristics of laser energy transfer within CFRP, this invention selects a portion of the material as samples for spot firing and rectangular cutting tests before processing CFRP with a CO2 continuous laser. By measuring the pits generated in the spot firing test, the distance D between the focusing lens of the laser engraving system and the material is determined, thus concentrating the energy input and improving the laser effect. On the other hand, by measuring the unevenness of the resin layer within the rectangular area (i.e., the rectangular surface fluctuation value), the surface energy accumulation, heat-affected zone, and energy transfer between layers are determined during laser action. This allows for an accurate evaluation of the thermal damage to the material caused by laser cutting or ablation under different conditions, and the determination of suitable laser processing conditions for the CFRP material. This reduces the work of optimizing and debugging laser processing conditions for CFRP materials of different specifications or structures, which is beneficial for subsequent large-scale material processing and improving the quality of processed products. Attached Figure Description

[0021] Figure 1 This is a data analysis graph of spot firing at different distances between the focusing lens and the sample in the experimental example. Curve 1 represents the average diameter, and curve 2 represents the continuous laser power density.

[0022] Figure 2 This is an analysis chart of the surface fluctuation values ​​of a rectangular surface after cutting under different scanning speed conditions in the experimental example.

[0023] Figure 3 This is an analysis chart of the surface fluctuation values ​​of the rectangular surfaces obtained after trial cutting at different scanning speeds and with different number of consecutive processing cycles in the experimental example. Detailed Implementation

[0024] The present invention is further illustrated by the following examples, but these are not intended to limit the invention. Specific experimental conditions and methods not specified in the following examples are generally conventional methods well known to those skilled in the art.

[0025] Example 1: A method for CO2 continuous laser cutting of CFRP material, comprising the following steps:

[0026] (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting.

[0027] (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. For every 1mm increase in distance D, spot firing is performed on the sample once. The range of distance D is 15mm to 27mm. The diameter of the pit generated by spot firing is measured twice, horizontally and vertically, and the average diameter is calculated according to Formula I. At the same time, the continuous laser power density is calculated according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value. Then perform a trial cut on the sample and cut a rectangle on the sample. Mark the center of the cut rectangle and then measure the height difference between the four corners of the rectangle and the center of the rectangle. Calculate the surface fluctuation value of the rectangle according to Formula III.

[0028] Formula I is D avg = (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm.

[0029] Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm.

[0030] Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; H Dif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm.

[0031] (3) Select different scanning speeds and continuous processing times, and repeatedly perform trial cutting on the sample. When the measured Fv is the minimum value, the thermal damage of the material is the lowest. Use the scanning speed and continuous processing times at this time as working parameters to cut the CFRP material to be cut. The scanning speed range is 3 to 7 mm / s, and the continuous processing times range is 1 to 20 times.

[0032] Example 2: A method for CO2 continuous laser cutting of CFRP material, comprising the following steps:

[0033] (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting.

[0034] (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. For every 0.5mm increase in distance D, perform spot firing on the sample once. The range of distance D is 23mm to 25mm. Measure the diameter of the pit generated by spot firing twice, horizontally and vertically, and calculate the average diameter according to Formula I. At the same time, calculate the continuous laser power density according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value. Then perform a trial cut on the sample and cut a rectangle on the sample. Mark the center of the cut rectangle and measure the height difference between the four corners of the rectangle and the center of the rectangle. Calculate the surface fluctuation value of the rectangle according to Formula III.

[0035] Formula I is D avg = (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm.

[0036] Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm.

[0037] Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; H Dif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm.

[0038] (3) Select different scanning speeds and continuous processing times, and repeatedly perform trial cutting on the sample. When the measured Fv is the minimum value, the thermal damage of the material is the lowest. Use the scanning speed and continuous processing times at this time as working parameters to cut the CFRP material to be cut. The scanning speed is any one of 3mm / s, 4mm / s, 5mm / s, 6mm / s and 7mm / s, and the continuous processing times are any one of 1, 5, 10, 15 and 20 times.

[0039] Example 3: A method for CO2 continuous laser cutting of CFRP material, comprising the following steps:

[0040] (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting.

[0041] (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. For every 1mm increase in distance D, spot firing is performed on the sample once. The range of distance D is 20mm to 25mm. The diameter of the pit generated by spot firing is measured twice, horizontally and vertically, and the average diameter is calculated according to Formula I. At the same time, the continuous laser power density is calculated according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value. Then perform a trial cut on the sample and cut a rectangle on the sample. Mark the center of the cut rectangle and then measure the height difference between the four corners of the rectangle and the center of the rectangle. Calculate the surface fluctuation value of the rectangle according to Formula III.

[0042] Formula I is D avg = (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm.

[0043] Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm.

[0044] Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; H Dif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm.

[0045] (3) Select different scanning speeds and continuous processing times, and repeatedly perform trial cutting on the sample. When the measured Fv is the minimum value, the thermal damage of the material is the lowest. Use the scanning speed and continuous processing times at this time as working parameters to cut the CFRP material to be cut. The scanning speed range is 3 to 7 mm / s, and the continuous processing times range is 1 to 20 times. The scanning speed is any one of 3 mm / s, 4 mm / s, 5 mm / s, 6 mm / s and 7 mm / s, and the continuous processing times are any one of 1, 5, 10, 15 and 20 times.

[0046] Experimental Example: CFRP material was selected and cut according to the method described in Example 1. The CFRP material contained carbon fibers woven in 0° and 90° directions, with 6 layers. The gaps between the layers were filled with resin, and the carbon fiber volume fraction was 72%. A CO2 continuous laser engraving and cutting system was used simultaneously. Figure 1 As shown, it includes components such as a processing platform, computer-aided control, air pump, water tank, and XY two-dimensional moving platform;

[0047] The cutting process includes the following steps:

[0048] (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting.

[0049] (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. Spot firing is performed on the sample once for every 1mm increase in distance D. The range of distance D is 15mm to 27mm. The diameter of the pit generated by spot firing is measured twice, horizontally and vertically, and the average diameter is calculated according to Formula I. At the same time, the continuous laser power density is calculated according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value, as shown in Table 1 and Figure 1 As shown, the continuous laser power density is highest when the distance D is 24 mm.

[0050] Then, a test cut is performed on the sample. A rectangle is cut out on the sample, the center of the cut rectangle is marked, and the height difference between the four corners of the rectangle and the center of the rectangle is measured. The surface fluctuation value of the rectangle is calculated according to Formula III.

[0051] Formula I is D avg= (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm.

[0052] Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm.

[0053] Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; H Dif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm.

[0054] (3) The scanning speeds were selected as 3 mm / s, 5 mm / s, and 7 mm / s, respectively, and the number of consecutive processing times were selected as 1, 5, and 10 times, respectively. The test cutting was repeated on the sample, and the measured Fv is shown in the figure. Figures 2-3 And Table 2.

[0055] according to Figure 2 It can be seen that when the number of continuous processing cycles is 1, Fv gradually decreases as the scanning speed increases. This is because as the scanning speed increases, the time that the continuous laser acts on the sample will be relatively reduced, resulting in less energy accumulation. This leads to a reduction in the phenomenon of surface resin thermal expansion or vaporization at the melting point. However, when the scanning speed is greater than 5 mm / s, its increase has no significant effect on energy accumulation. Therefore, appropriately increasing the scanning speed can effectively reduce the energy accumulation of continuous laser ablation of CFRP and improve the processing quality.

[0056] according to Figure 3 It can be observed that with the increase of consecutive processing times, the flow rate (Fv) increases, and the energy accumulation on the material surface becomes more significant. At a scanning speed of 3 mm / s, the Fv reaches a maximum of 39.55 μm after 10 processing cycles. The Fv increase after one and five rectangular cutting tests is not substantial. This may be because there is a threshold for interlayer energy transfer in the carbon fibers beneath the surface resin layer. When this threshold is not breached and is about to be reached, energy is accumulated or preferentially used for interlayer transfer. At scanning speeds of 5 mm / s and 7 mm / s, the Fv is much lower than that at 3 mm / s. This may be because the increased scanning speed results in insufficient energy input. Since the axial thermal conductivity of carbon fibers is much higher than their radial thermal conductivity, energy transfer preferentially occurs at the interlayer level, leaving no energy for interlayer transfer.

[0057] Table 2 shows that after one and five rectangular cuts at a scanning speed of 3 mm / s, the resin surface on the front side showed no significant fluctuations. However, after five rectangular cuts, the resin layer on the back side showed charring. This is because energy is transferred to the back side through the interlayer, and the high temperature vaporizes and seals some of the resin connected to the carbon fibers. Since epichlorohydrin is added during the epoxy resin preparation process, a charred yellow mark is produced. As the number of consecutive processing cycles continues to increase, the energy accumulates and increases towards the interlayer. When the scanning speed is 5 mm / s and the number of consecutive processing cycles is 10, charring occurs on the resin layer on the back side. However, when the scanning speed is 7 mm / s and the number of consecutive processing cycles is 10, no significant change is observed on the back side.

[0058] Table 1. Measurement results of pits obtained from point D at different distances.

[0059]

[0060] Table 2. Appearance of materials after cutting under different scanning speeds and number of consecutive processing cycles.

[0061]

[0062] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for CO2 continuous laser cutting of CFRP material, characterized in that: Includes the following steps: (1) The CO2 continuous laser engraving and cutting system was used to cut CFRP material. The CO2 continuous laser engraving and cutting system was debugged and the following working parameters were set: power of 100W, two-dimensional moving platform stroke of 1300mm*900mm, light output time of 1s, and light output mode of point shooting. (2) Take a portion of the CFRP material to be cut as a sample and place the sample on the CO2 continuous laser engraving and cutting system, so that the distance D between the focusing lens and the sample is 15mm. Then adjust the distance D and perform spot firing on the sample. For every 0.5mm or 1mm increase in distance D, perform spot firing on the sample once. Measure the diameter of the pit generated by spot firing twice, both horizontally and vertically, and calculate the average diameter according to Formula I. At the same time, calculate the continuous laser power density according to Formula II. When the continuous laser power density is the maximum, the corresponding distance D is the optimal value. Then perform a trial cut on the sample and cut a rectangle on the sample. Mark the center of the cut rectangle and measure the height difference between the four corners of the rectangle and the center of the rectangle. Calculate the surface fluctuation value of the rectangle according to Formula III. Formula I is D avg = (D1 + D2) / 2, where D1 is the transverse diameter of the pit, in μm; D2 is the vertical diameter of the pit, in μm; D avg The average diameter is in mm. Formula II is I0 = 4P / πD avg 2 Where I0 is the CO2 continuous laser power density, in W / mm². 2 P represents laser power, measured in W; D avg The average diameter is in mm. Formula III is Fv= Where Fv is the surface ripple value of the rectangular surface, in μm; H Dif This represents the height difference between the four corners of the rectangle and the center of the rectangle, in μm. (3) Select different scanning speeds and number of consecutive processing times, and repeat the trial cutting on the sample. When the measured Fv is the minimum value, the thermal damage of the material is the lowest. Use the scanning speed and number of consecutive processing times at this time as working parameters to cut the CFRP material to be cut.

2. The method for CO2 continuous laser cutting of CFRP material according to claim 1, characterized in that: The scanning speed range is 3 to 7 mm / s, and the number of continuous processing cycles ranges from 1 to 20.

3. The method for CO2 continuous laser cutting of CFRP material according to claim 2, characterized in that: The scanning speed is any one of 3mm / s, 4mm / s, 5mm / s, 6mm / s and 7mm / s.

4. The method for CO2 continuous laser cutting of CFRP material according to claim 2, characterized in that: The number of consecutive processing cycles is any one of 1, 5, 10, 15, and 20.

5. The method for CO2 continuous laser cutting of CFRP material according to claim 1, characterized in that: The distance D is in the range of 15mm to 27mm.

6. The method for CO2 continuous laser cutting of CFRP material according to claim 5, characterized in that: The distance D is in the range of 23mm to 25mm.

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