Laser processing method and device for heterogeneous laminated components

Abstract

The present invention discloses a laser processing method and apparatus for a heterogeneous laminated component, comprising the following steps: determining a spiral scanning trajectory during laser scanning; controlling a laser to output a laser beam so that the laser beam starts from the center of the spiral and scans along the spiral scanning trajectory across the upper surface of the heterogeneous laminated component, and controlling the laser beam focus to move downward after each spiral scan; acquiring an acoustic emission signal in real time during the laser scanning process using an acoustic emission signal acquisition device to generate a time domain curve and / or a frequency distribution curve of the acoustic emission signal, and determining whether the metal layer of the heterogeneous laminated component has been exposed based on the time domain curve and / or frequency distribution curve; and stopping the laser when it is determined that the metal layer of the heterogeneous laminated component has been exposed. The present invention employs an equal-area variable-pitch spiral scanning strategy to effectively homogenize the energy distribution in the processing area, ensuring a balanced laser energy distribution during each layer of laser scanning. Furthermore, when the metal layer is confirmed to be exposed, the laser is controlled to stop emitting light, thereby allowing a large area of ​​the metal layer to be exposed at the bottom of the blind hole while preventing the exposed metal material from being excessively ablated.

Description

Technical Field

[0001] The present invention belongs to the field of laser processing technology, and in particular to a method and device for laser processing of heterogeneous laminated components. Background Art

[0002] Heterogeneous laminated components, such as carbon fiber reinforced plastic (CFRP)-copper foil (Cu)-carbon fiber reinforced plastic (CFRP), integrate metal (such as ultrathin copper foil) with a thickness of ≤10μm within two sheets of CFRP to form a sandwich structure. Microblind holes are then machined on the surface to expose the metal in the interlayer, forming an electrically connected metal column structure to autonomously control the electromagnetic characteristics of multi-disturbed aerospace conditions. Currently, short-pulse lasers are used to process these microblind holes.

[0003] Because the laser diameter and focal depth are only tens of microns, a single laser scan can only form a kerf tens of microns wide and deep. Therefore, to obtain blind holes with larger diameters and depths (e.g., 1 mm each), a top-down laser scanning method is required. That is, after the laser scan of the previous layer is completed, a certain thickness of material is removed by the laser, exposing the next layer to be processed. At this time, the laser focus is adjusted downward by a certain distance, so that the laser is refocused on the bottom of the blind hole, and the laser scanning process of the next layer of material is carried out. This repetitive process eventually achieves a blind hole of a specific depth and size.

[0004] However, since the metal in heterogeneous laminated components is sandwiched between CFRP, the spatial position of the metal is difficult to accurately locate. As a result, when laser scanning and drilling, it is easy for the metal to be ablated and removed, or a large amount of composite material is still covered on the metal, making it difficult to stably expose the metal at the bottom of the blind hole. At the same time, the scanning trajectory filling method of existing laser layer-by-layer scanning is mostly equidistant spirals or concentric circles. During the laser scanning process from the outside to the inside, the heat accumulation in the central area is significantly higher than that in the outer area, causing the metal to be extremely easily damaged and difficult to retain intact. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a laser processing method and device for heterogeneous laminated components, which adopts an equal-area variable-pitch spiral scanning strategy to effectively homogenize the energy distribution in the processing area, so that the laser energy distribution is balanced during the laser scanning process of each layer. At the same time, when it is confirmed that the metal layer has been exposed, the laser is controlled to stop the light, so that the metal layer can be exposed to a large area at the bottom of the blind hole while preventing the exposed metal material from being excessively processed and ablated.

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

[0007] In one aspect, a method for laser processing a heterogeneous laminated component is provided, comprising the following steps:

[0008] Determine the spiral scanning trajectory during laser scanning;

[0009] The laser is controlled to output a laser beam, and the laser beam is caused to start from the center starting point of the spiral line and scan along the spiral line scanning trajectory on the upper surface of the heterogeneous laminated component, and each time a circle of the spiral line is scanned, the focus of the laser beam is controlled to move downward; and during the laser scanning process, an acoustic emission signal is acquired in real time by an acoustic emission signal acquisition device, a time domain curve and / or a frequency distribution curve of the acoustic emission signal is generated, and whether the metal layer of the heterogeneous laminated component has been exposed is determined based on the time domain curve and / or the frequency distribution curve;

[0010] When it is determined that the metal layer of the heterogeneous stacked component has been exposed, the laser stops emitting light;

[0011] In the spiral scanning trajectory, the distance r between the end of the nth spiral and the starting point of the spiral center n The following conditions must be met:

[0012]

[0013] Where k represents the area between the nth and n-1th spirals, n is a positive integer greater than or equal to 2, and the area between two adjacent spirals is equal to the area contained by the first spiral.

[0014] And the distance Δd between the starting and ending points of the n-th spiral n The following conditions must be met:

[0015]

[0016] And the distance between the starting and ending points of the first spiral

[0017] Preferably, the starting point of the spiral center and the end of each spiral are located on the same straight line.

[0018] Preferably, the end of the (n-1)th spiral is the starting end of the nth spiral.

[0019] Preferably, determining whether the metal layer of the heterogeneous laminated component is exposed according to the time domain curve includes the following:

[0020] When the voltage value of the acoustic emission signal increases and the voltage value growth rate is greater than or equal to the voltage value growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the voltage value growth rate threshold has a value range of [0.05V, 0.1V].

[0021] 5. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein determining whether the metal layer of the heterogeneous laminated structure is exposed according to the frequency distribution curve comprises the following steps:

[0022] When the volume of the acoustic emission signal in the 0-600kHz frequency band increases and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 2dB].

[0023] Preferably, when the volume of the acoustic emission signal in the 400-600kHz frequency band increases and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 1.5dB].

[0024] On the other hand, a laser processing device for implementing the above-mentioned laser processing method for heterogeneous laminated components is also provided, comprising:

[0025] A laser processing unit, which is used to output a laser beam and make the laser beam act on the surface of the heterogeneous laminated component;

[0026] a control unit connected to the laser processing unit, configured to control the laser beam to scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory starting from the center starting point of the spiral line, and controlling the focus of the laser beam to move downward each time a spiral line scan is completed;

[0027] An acoustic emission signal acquisition device connected to the control unit, configured to acquire the acoustic emission signal in real time during the laser scanning process and generate a time domain curve and / or a frequency distribution curve of the acoustic emission signal;

[0028] and a data processing unit connected to the control unit and the acoustic signal acquisition device, configured to determine whether the metal layer of the heterogeneous laminated component has been exposed based on the time domain curve and / or the frequency distribution curve, and to generate a control signal and send it to the control unit when the metal layer is considered to have been exposed;

[0029] The control unit controls the laser processing unit to stop emitting light according to the control signal.

[0030] Preferably, the laser processing unit includes a nanosecond ultraviolet laser.

[0031] The beneficial effects of using the present invention are:

[0032] The present invention adopts an equal-area variable-pitch spiral scanning strategy when preparing blind holes by laser scanning. This strategy allows each spiral scanning track to cover an equal area, forming a variable-pitch scanning track with sparse inner and dense outer areas. This ensures a balanced distribution of laser energy during each laser scanning layer, further ensuring similar material removal efficiencies in the inner and outer areas during each layer processing, thereby achieving uniform material removal within the processing area.

[0033] At the same time, during the entire laser scanning process, the acoustic emission signal is obtained in real time by the acoustic signal acquisition device, and whether the metal layer of the heterogeneous laminated component has been exposed is further determined based on the time domain curve and / or the frequency distribution curve. When it is confirmed that the metal layer has been exposed, the laser is controlled to stop the light, so that the metal layer can be exposed to a large area at the bottom of the blind hole while preventing the exposed metal material from being excessively processed and ablated. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the structure of a heterogeneous laminated component;

[0035] Figure 2 Schematic diagram of a medium-pitch spiral scanning track in the prior art and a medium-area variable-pitch spiral scanning track of the present invention;

[0036] Figure 3 Schematic diagram of the steps of the laser processing method for heterogeneous laminated components in the present invention;

[0037] Figure 4 The blind hole bottom morphology characteristic images corresponding to different laser processing times when determining the voltage value growth rate threshold in the present invention;

[0038] Figure 5 is the time domain curve of the acoustic emission signal in the present invention;

[0039] Figure 6 The bottom morphology feature images of the blind hole corresponding to different laser processing times when determining the volume growth rate threshold in the present invention;

[0040] Figure 7 This is the volume distribution curve corresponding to different laser processing times and different frequency bands in the present invention;

[0041] Figure 8 The topographic feature images of the bottom of the blind hole when scanning along the medium-pitch spiral scanning track of the prior art and along the medium-area variable-pitch spiral scanning track of the present invention;

[0042] Figure 9 It is a schematic structural diagram of the laser processing device for heterogeneous laminated components in the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of this technical solution more clear, the following technical solution is further described in detail in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of this technical solution.

[0044] Example 1:

[0045] The present invention proposes a laser processing method for heterogeneous laminated components. In this embodiment, Figure 1 As shown, the heterogeneous laminated component includes a carbon fiber reinforced composite material (CFRP)-metal layer (such as copper foil (Cu))-carbon fiber reinforced composite material (CFRP) component, which is a sandwich structure. The metal layer is located between two layers of carbon fiber reinforced composite materials. On this basis, as shown in FIG. Figure 3 As shown, the laser processing method for heterogeneous laminated components includes the following steps:

[0046] S1. Determine the spiral scanning trajectory during laser scanning, and the distance r between the end of the nth spiral and the starting point O of the spiral center n The following conditions are met:

[0047]

[0048] Where k represents the area between the nth and n-1th spirals, n is a positive integer greater than or equal to 2, and the area between two adjacent spirals is equal to the area contained by the first spiral.

[0049] And the distance Δd between the starting and ending points of the n-th spiral n The following conditions are met:

[0050]

[0051] In this embodiment, the starting point of the first spiral is the starting point O of the spiral center, so the distance between the starting point and the end point of the first spiral is The end of the n-1th spiral is the starting point of the nth spiral; at the same time, the starting point O of the spiral center and the end of each spiral are on the same straight line;

[0052] The derivation process of the above formula is as follows:

[0053] Define k as the area contained by the first spiral turn, and express this area k by formula (1):

[0054] k=πr1 2 (1)

[0055] For ease of calculation, the area k is simplified to the area of ​​a circle. This simplified calculation has a certain error, but as the number of spiral coils increases, the error will become smaller and smaller. Where r1 represents the distance between the end of the first spiral coil and the starting point O of the spiral center, and r1 is a known value.

[0056] At the same time, k is defined as the area between two adjacent spirals, which is an approximately circular area. Since the area between each two adjacent spirals is k, the area contained in the nth spiral is nk. At the same time, the area contained in the nth spiral is also equal to Therefore, it is established From this we can conclude

[0057] Furthermore, since the end of the n-1th spiral is the starting point of the nth spiral, the distance Δd is expressed by formula (2): n :

[0058] Δd n =r n -r n-1 (2)

[0059] Will Substituting into the above formula (4), we have

[0060] Thus, by obtaining r n and Δd n The drawing of the spiral scanning trajectory can be realized, and the spacing between adjacent spirals in the spiral scanning trajectory (i.e., the distance Δd n ) gradually decreases from the inside to the outside, but the area between two adjacent spirals remains constant, which effectively improves the situation in which the center of the spiral is severely ablated and the edge is insufficiently ablated due to uneven laser energy distribution during blind hole processing;

[0061] S2. Control the laser to output a laser beam, and make the laser beam start from the starting point O at the center of the spiral line and scan along the spiral line trajectory, scanning the upper CFRP surface of the heterogeneous laminated component, and control the focus of the laser beam to move downward after each spiral line scan is completed;

[0062] During the laser scanning process, an acoustic emission signal is acquired in real time by an acoustic emission signal acquisition device to generate a time domain curve and / or a frequency distribution curve of the acoustic emission signal, and whether the metal layer of the heterogeneous laminated component has been exposed is determined based on the time domain curve and / or the frequency distribution curve;

[0063] S3. When it is determined that the metal layer of the heterogeneous stacked structure has been exposed, the laser stops emitting light.

[0064] Furthermore, in step S2, determining whether the metal layer of the heterogeneous laminated component is exposed according to the time domain curve and / or the frequency distribution curve includes the following:

[0065] When the voltage value of the acoustic emission signal increases and the voltage value growth rate is greater than or equal to the voltage value growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the voltage value growth rate threshold is in the range of [0.05V, 0.1V];

[0066] The voltage value of the acoustic emission signal is the root mean square value (RMS) of the acoustic emission signal (that is, the effective power value of the acoustic emission signal), which can be obtained by the following formula:

[0067]

[0068] And / or, when the volume of the acoustic emission signal in the frequency band of 0-600 kHz increases, and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 2dB]. Preferably, when the volume of the acoustic emission signal in the frequency band of 400-600 kHz increases, and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 1.5dB].

[0069] The volume of the acoustic emission signal is the distribution result of the acoustic emission signal on different frequency components obtained by converting the frequency distribution curve of the acoustic emission signal from the time domain to the frequency domain through Fourier transform (FFT), which can be obtained by the following formula:

[0070]

[0071] Furthermore, the process of determining the voltage value growth rate threshold is as follows:

[0072] Obtain the blind hole bottom morphology feature images corresponding to different laser processing time T; for example, Figure 4 As shown in (a)-(e), the upper layer of CFRP has not been completely removed in the first 5 seconds of laser processing. After 6 seconds of laser processing, Figure 4 As shown in (f), the metal layer (such as copper foil (Cu)) begins to be exposed at the bottom of the blind hole, as shown in Figure 4As shown in (g)-(i), as the laser processing time increases, a ring-shaped metal layer (i.e., "Cu") with a gradually increasing diameter is gradually exposed. It should be noted that when the laser scanning is continued, an outward-expanding, newly exposed ring-shaped metal layer will continue to form, and the exposed metal layer inside the ring-shaped metal layer will be laser ablated during the subsequent laser scanning process to form a black ablation area inside the ring-shaped metal layer.

[0073] Acquire a time domain curve of an acoustic emission signal, wherein the time domain curve of the acoustic emission signal includes voltage values ​​corresponding to different laser processing time lengths T; for example, Figure 5 That is, it shows the time domain curve of the acoustic emission signal during the entire processing process, where the "time" in the horizontal axis is the laser processing time T, and the "amplitude" in the vertical axis is the voltage value of the acoustic emission signal;

[0074] The voltage value change trend of the acoustic emission signal time domain curve is matched with the blind hole bottom morphology characteristic image to determine the voltage value change rate (which can be the voltage value growth rate or decrease rate) corresponding to the exposure of the metal layer, and the voltage value change threshold is determined according to the voltage value change rate;

[0075] For example, Figure 5 As shown in the figure, based on the voltage value change on the acoustic emission signal time domain curve, the acoustic emission signal time domain curve can be divided into three stages I to III. In stage I, the laser acts on the soft CFRP and gradually stabilizes. The voltage value of the acoustic emission signal generally shows a decreasing trend with the increase of laser processing time T, from 0.48V at 0 seconds to 0.23V at 2.5 seconds. During this period, the voltage value decreases at a rate of about 0.1V / s. In stage II, the CFRP above the metal layer is stably and evenly removed, and the voltage value of the acoustic emission signal generally tends to In the state of stable fluctuation, the voltage value fluctuation range is between 0.25 and 0.3V, and the growth rate and decline rate of the voltage value are both lower than 0.02V / s. Finally, in stage III, the laser processing reaches the dense metal layer (copper foil) and the scope of action gradually increases. Because the vibration amplitude of the dense metal layer is greater than that of CFRP, the voltage value shows a trend of increasing with time, increasing from 0.3V at 5.5 seconds to 0.63V at 9.5 seconds. The voltage value growth rate in this period is greater than 0.08V / s, and the voltage value change in this stage is similar to that in the CFRP laser processing. Figure 4 In the figure, the bottom morphology of the blind hole after 6-9 seconds of laser processing is basically corresponding;

[0076] Therefore, it can be considered that when the voltage value of the acoustic emission signal time domain curve increases and the growth rate is ≥0.08V / s, the laser beam has reached the metal layer-CFRP interface and the metal layer has been exposed. Therefore, 0.08V / s can be determined as the voltage value growth rate threshold. It should be noted that when the metal layer is not copper foil (Cu), the voltage value growth rate may not be 0.08V / s. Therefore, based on the material properties of different metal layers, the value range of the voltage value growth rate threshold is determined to be [0.05V, 0.1V] in this embodiment.

[0077] The process of determining the volume growth rate threshold is as follows:

[0078] Obtain the blind hole bottom morphology feature images corresponding to different laser processing time T; for example, Figure 6 (a)-(d) show the bottom morphology feature images of the blind hole after laser processing for 1 second, 2.5 seconds, 5.5 seconds, and 9.5 seconds, respectively, corresponding to the four states of just starting to process the CFRP material, not processing the metal layer, the metal layer just exposed, and continuous laser scanning to expose the annular metal layer;

[0079] Obtain a frequency and volume distribution curve of the acoustic emission signal, wherein the frequency and volume distribution curve includes the acoustic emission signal frequency corresponding to different laser processing durations and the volume corresponding to the frequency; for example, Figure 7 That shows that Figure 6 The corresponding acoustic emission signal frequency and volume distribution curve, where the "frequency" in the horizontal axis is the frequency of the acoustic emission signal, and the "amplitude" in the vertical axis is the volume corresponding to the frequency;

[0080] For example, from Figure 7 As can be seen in parts (a) and (b), the volume of the AE signal in the 0-400kHz frequency band shows an overall downward trend as the laser processing time T increases from 1s to 2.5s. For example, the volume amplitude at 60kHz decreases from -23dB to -37dB, and the volume amplitude at 350kHz decreases from -30dB to -35dB. The volume amplitudes of the AE signals in the 400-600kHz and 600-1000kHz frequency bands are basically the same, indicating that the AE signal energy in these frequency bands has hardly changed. During this process, the laser beam only interacts with the loose CFRP material and has not yet processed the metal layer.

[0081] from Figure 7It can be seen from parts (b) and (c) that when the laser processing time T increases from 2.5s to 5.5s, the volume of the acoustic emission signals in the two frequency bands of 0-400kHz and 400-600kHz shows an overall upward trend. For example, the volume amplitude of the 60kHz frequency increases from -37dB to -33dB, the volume amplitude of the 350kHz frequency increases from -35dB to -28dB, and the volume amplitude of the 520kHz frequency increases from -56dB to -49dB, while the volume amplitude of the acoustic emission signal in the 600-1000kHz frequency band hardly changes. In this process, when the laser processing time T is 5.5s, the metal layer begins to be exposed. At this time, the laser beam acts on the metal layer. Under the same energy impact, the dense metal material is more violently affected by the laser pulse impact. The resulting high-frequency elastic vibration will increase the volume of the high-frequency acoustic emission signal, especially the acoustic emission signal volume in the 400-600kHz frequency band.

[0082] Likewise, from Figure 7 It can be seen from parts (c) and (d) that when the laser processing time T increases from 5.5s to 9.5s, the volume of the acoustic emission signal in the two frequency bands of 0-400kHz and 400-600kHz shows an overall upward trend. For example, the volume amplitude of the 60kHz frequency increases from -33dB to -28dB, the volume amplitude of the 350kHz frequency increases from -28dB to -24dB, and the volume amplitude of the 520kHz frequency increases from -49dB to -44dB. Similarly, the volume amplitude of the acoustic emission signal in the 600-1000kHz frequency band hardly changes. During this stage, the exposed area of ​​the metal layer gradually increases, and more and more metal materials interact with the laser, which makes the volume amplitude of the acoustic emission signal show an overall upward trend.

[0083] It can be seen that when the volume of the acoustic emission signal in the 0-600kHz frequency band of the acoustic emission signal increases during laser processing, and the average incremental rate of the volume in each frequency band is greater than 2dB / s, it can be determined that the laser processing has reached the metal layer interface. When the volume of the signal in the 400-600kHz frequency band increases significantly (i.e., 1.25dB / s≦growth rate≦1.5dB / s), it can be considered that the laser processing has reached a large area of ​​the metal layer, and the laser should be guided to stop processing. Therefore, considering the volume growth in each frequency band, in this embodiment, for the 0-600kHz frequency band, the value range of the volume growth rate threshold can be determined as [1.25dB, 2dB]. Preferably, for the 400-600kHz frequency band, the value range of the volume growth rate threshold can be determined as [1.25dB, 1.5dB].

[0084] from Figure 2It can be seen from the figure that in the prior art, when laser scanning is performed along an equidistant spiral scanning trajectory, the spacing between the spiral lines is constant at d / 2n, as shown in FIG. Figure 8 As can be seen from parts (a) to (f) in the figure, only an annular metal layer (such as copper foil (Cu)) exists at the bottom of the blind hole processed by the equidistant spiral scanning track. The metal layer in the central area is removed by laser ablation, forming a black area in the center. The edge area is still covered with a large amount of CFRP. The minimum and maximum circumscribed circle diameters of the annular metal layer are 348μm ( Figure 8 (f) in), 518μm( Figure 8 In (d)), the minimum exposed area of ​​the metal layer is 0.095mm 2 ( Figure 8 (f)) in the figure is 0.210mm at most. 2 ( Figure 8 In (d)), the maximum taper of the blind hole is 0.362 and the minimum is 0.247.

[0085] And as Figure 8 As shown in parts (A) to (F) of the figure, when laser scanning is performed along the equal-area (i.e., the areas between adjacent spiral lines are equal) variable-pitch spiral scanning trajectory in this embodiment, a non-annular, almost completely circular metal layer is exposed at the bottom of the prepared blind hole. The metal layer in the central area is not significantly ablated and still shows the color of the metal itself. The reason is that the equal-area variable-pitch spiral scanning strategy in this embodiment can effectively regulate the energy distribution in the processing area, reduce the heat accumulation in the central area, and enhance the heat input in the edge area. While ensuring uniform erosion of the CFRP material in the processing area, it can also avoid the ablation of the exposed metal layer in the central area. Compared with the traditional processing method, the minimum and maximum diameters of the metal layer exposed at the bottom of the blind hole are 542μm ( Figure 8 (A) in), 783μm( Figure 8 (D) in the figure), the minimum exposed area of ​​the metal layer is 0.231 mm2 ( Figure 8 (A) in the figure), the maximum is 0.481mm2( Figure 8 (D) in the figure, and the blind hole taper is 0.261 at most and 0.113 at least.

[0086] Therefore, the equal-area variable-pitch spiral scanning strategy in this embodiment can make the coverage area of ​​each spiral scanning trajectory equal, forming a variable-pitch scanning trajectory that is sparse inside and dense outside, thereby effectively homogenizing the energy distribution in the processing area, making the laser energy distribution balanced during each layer of laser scanning, and further making the material abrasion efficiency of the inner and outer circle areas similar during each layer of processing, thereby achieving uniform material removal in the processing area, avoiding the problem of severe energy accumulation in the central area and insufficient energy in the edge area, resulting in uneven material abrasion.

[0087] Example 2:

[0088] This embodiment provides a laser processing device for implementing the laser processing method of the heterogeneous laminated component described in Example 1, such as Figure 9 As shown, it includes:

[0089] A laser processing unit 100, which is used to output a laser beam and make the laser beam act on the surface of the heterogeneous laminated component; preferably, the laser processing unit 100 includes a nanosecond ultraviolet laser;

[0090] a control unit 200 connected to the laser processing unit 100 and configured to control the laser beam to scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory starting from the spiral center starting point O of the spiral scanning trajectory in step S1, and to control the focus of the laser beam to move downward each time a spiral scan is completed;

[0091] An acoustic emission signal acquisition device 300, connected to the control unit 200, is used to acquire the acoustic emission signal in real time during the laser scanning process and generate a time domain curve and / or a frequency distribution curve of the acoustic emission signal;

[0092] and a data processing unit 400 connected to the control unit 200 and the acoustic signal acquisition device 300, configured to determine whether the metal layer of the heterogeneous laminated component has been exposed based on the time domain curve and / or the frequency distribution curve, and to generate a control signal and send it to the control unit 200 when the metal layer is considered to have been exposed; wherein the process of determining whether the metal layer of the heterogeneous laminated component has been exposed based on the time domain curve and / or the frequency distribution curve is the same as step S2;

[0093] The control unit 200 controls the laser processing unit 100 to stop emitting light according to the control signal.

[0094] In summary, the present invention adopts an equal-area variable-pitch spiral scanning strategy when preparing blind holes by laser scanning. This strategy allows each spiral scanning track to cover an equal area, forming a variable-pitch scanning track that is sparse inside and dense outside. This effectively homogenizes the energy distribution in the processing area, ensuring a balanced laser energy distribution during each layer of laser scanning. Furthermore, the material ablation efficiency of the inner and outer ring areas during each layer of processing is similar, thereby achieving uniform material removal within the processing area and avoiding the problem of uneven material ablation caused by severe energy accumulation in the central area and insufficient energy in the edge areas.

[0095] At the same time, during the entire laser scanning process, the acoustic emission signal is obtained in real time by the acoustic signal acquisition device, and whether the metal layer of the heterogeneous laminated component has been exposed is further determined based on the time domain curve and / or the frequency distribution curve. When it is confirmed that the metal layer has been exposed, the laser is controlled to stop the light, so that the metal layer can be exposed to a large area at the bottom of the blind hole while preventing the exposed metal material from being excessively processed and ablated.

[0096] The above content is only a preferred embodiment of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scope based on the ideas of the present technical content. As long as these changes do not deviate from the concept of the present invention, they all fall within the scope of protection of this patent.

Claims

1. A laser processing method for a heterogeneous laminated component, characterized in that: The steps include: Determine the spiral scanning trajectory during laser scanning; The laser is controlled to output a laser beam, and the laser beam is caused to start from the center starting point of the spiral line and scan along the spiral line scanning trajectory on the upper surface of the heterogeneous laminated component, and each time a circle of the spiral line is scanned, the focus of the laser beam is controlled to move downward; and during the laser scanning process, an acoustic emission signal is acquired in real time by an acoustic emission signal acquisition device, a time domain curve and / or a frequency distribution curve of the acoustic emission signal is generated, and whether the metal layer of the heterogeneous laminated component has been exposed is determined based on the time domain curve and / or the frequency distribution curve; When it is determined that the metal layer of the heterogeneous stacked component has been exposed, the laser stops emitting light; In the spiral scanning trajectory, the distance r between the end of the nth spiral and the starting point of the spiral center n The following conditions must be met: Where k represents the area between the nth and n-1th spirals, n is a positive integer greater than or equal to 2, and the area between two adjacent spirals is equal to the area contained by the first spiral. And the distance Δd between the starting and ending points of the n-th spiral n The following conditions must be met: And the distance between the starting and ending points of the first spiral 2. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein: The starting point of the spiral center and the end of each spiral circle are all located on the same straight line.

3. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein: The end of the n-1th spiral is the starting point of the nth spiral.

4. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein: Determining whether the metal layer of the heterogeneous stacked component is exposed according to the time domain curve includes the following steps: When the voltage value of the acoustic emission signal increases and the voltage value growth rate is greater than or equal to the voltage value growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the voltage value growth rate threshold has a value range of [0.05V, 0.1V].

5. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein: Determining whether the metal layer of the heterogeneous stacked component is exposed according to the frequency distribution curve includes the following steps: When the volume of the acoustic emission signal in the 0-600kHz frequency band increases and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 2dB].

6. The laser processing method for a heterogeneous laminated structure according to claim 5, wherein: When the volume of the acoustic emission signal in the 400-600kHz frequency band increases and the volume growth rate is greater than or equal to the volume growth rate threshold, it is considered that the metal layer of the heterogeneous laminated component has been exposed, and the value range of the volume growth rate threshold is [1.25dB, 1.5dB].

7. A laser processing device for implementing the laser processing method for a heterogeneous laminated structure according to any one of claims 1 to 6, characterized in that: include: A laser processing unit, which is used to output a laser beam and make the laser beam act on the surface of the heterogeneous laminated component; a control unit connected to the laser processing unit, configured to control the laser beam to scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory starting from the center starting point of the spiral line, and controlling the focus of the laser beam to move downward each time a spiral line scan is completed; An acoustic emission signal acquisition device connected to the control unit, configured to acquire the acoustic emission signal in real time during the laser scanning process and generate a time domain curve and / or a frequency distribution curve of the acoustic emission signal; and a data processing unit connected to the control unit and the acoustic signal acquisition device, configured to determine whether the metal layer of the heterogeneous laminated component has been exposed based on the time domain curve and / or the frequency distribution curve, and to generate a control signal and send it to the control unit when the metal layer is considered to have been exposed; The control unit controls the laser processing unit to stop emitting light according to the control signal.

8. The laser processing device according to claim 7, wherein: The laser processing unit includes a nanosecond ultraviolet laser.

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