Heterogeneous laminated component laser processing method and device

Abstract

The invention discloses a laser processing method and device for a heterogeneous laminated component. The laser processing method comprises the following steps: determining a spiral line scanning track during laser scanning; a laser is controlled to output a laser beam, the laser beam is made to scan the upper surface of the heterogeneous laminated component from the center starting point of the spiral line along the spiral line scanning track, and the focus of the laser beam is controlled to move downwards every time scanning of a circle of spiral line is completed; in the laser scanning process, acoustic emission signals are acquired in real time through acoustic emission signal acquisition equipment, a time domain curve and / or a frequency distribution curve of the acoustic emission signals are / is generated, and whether a metal layer of the heterogeneous laminated component is exposed or not is determined according to the time domain curve and / or the frequency distribution curve; and when it is determined that the metal layer of the heterogeneous laminated component is exposed, the laser stops emitting light. According to the method, an equal-area variable-interval spiral scanning strategy is adopted, so that energy distribution of a machining area is effectively homogenized, laser energy distribution in the laser scanning process of each layer is balanced, meanwhile, when it is confirmed that the metal layer is exposed, the laser is controlled to stop light, and the metal layer can be exposed to the bottom of the blind hole in a large area while the laser energy distribution is balanced. And the exposed metal material is prevented from being removed by excessive processing and ablation.

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 composite (CFRP)-copper foil (Cu)-carbon fiber reinforced composite (CFRP) integrate metal with a thickness of ≤10μm (such as ultra-thin copper foil) inside two pieces of CFRP to form a sandwich structure, and process array micro blind holes on the surface to expose the middle sandwich metal to form a metal column electrical correlation structure to autonomously control the electromagnetic characteristics of multi-disturbance aerospace conditions. At present, there are technical means to process the above-mentioned micro blind holes using short-pulse lasers.

[0003] Since the laser diameter and focal depth are only tens of microns, a single laser scan can only form a slit with a width and depth of tens of microns. Therefore, in order to obtain a blind hole with a larger diameter and depth (such as 1mm), it is necessary to use a top-down laser scanning layer by layer method for processing, that is, when the laser scanning of the previous layer is completed, a certain thickness of material is removed by laser ablation, exposing the next layer of material to be processed. At this time, the laser focus is adjusted to move downward a certain distance, so that the laser is refocused on the bottom of the blind hole, and the laser scanning processing of the next layer of material is carried out. This reciprocating process eventually achieves blind hole processing of a specific depth and size.

[0004] However, since the metal in the heterogeneous laminated components is sandwiched in CFRP, the spatial position of the metal is difficult to accurately locate, resulting in the metal being easily ablated away or a large amount of composite material still covering the metal during laser scanning and drilling, making it difficult to stably expose the metal at the bottom of the blind hole. At the same time, the existing laser layer-by-layer scanning scanning trajectory filling method is mostly equidistant spiral lines or concentric circles. During the laser scanning process from the outside to the inside, the heat accumulation in the center area is significantly higher than that in the outer area, causing the metal to be easily damaged and difficult to retain intact. Summary of the invention

[0005] In order 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] On the one hand, a laser processing method for a heterogeneous laminated component is provided, which comprises 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 made to start from the center starting point of the spiral line, scan along the spiral line scanning trajectory, and scan 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, the 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 according to 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] Wherein, 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 nth spiral n The following conditions must be met:

[0015]

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

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

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

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

[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 of a heterogeneous laminated component according to claim 1, characterized in that determining whether the metal layer of the heterogeneous laminated component has been exposed according to the frequency distribution curve comprises the following contents:

[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 start from the spiral center starting point of the spiral scanning trajectory and scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory, and control the focus of the laser beam to move downward after each spiral scanning.

[0027] An acoustic emission signal acquisition device, which is connected to the control unit and 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;

[0028] and a data processing unit connected to the control unit and the acoustic signal acquisition device, for determining whether the metal layer of the heterogeneous laminated component has been exposed according to the time domain curve and / or the frequency distribution curve, and generating a control signal when the metal layer is considered to have been exposed, and sending the control signal to the control unit;

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

[0030] Preferably, the laser processing unit comprises 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, which can make the coverage area of ​​each spiral scanning track equal, forming a variable-pitch scanning track with sparse inside and dense outside, so that the laser energy distribution is balanced during each layer of laser scanning, and further makes the material ablation efficiency of the inner circle and the outer circle area similar during each layer processing, so as to achieve uniform material removal in the processing area;

[0033] At the same time, during the entire laser scanning process, the acoustic emission signal is acquired 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 is a 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 It is a schematic diagram of the steps of the laser processing method of the heterogeneous laminated component in the present invention;

[0037] Figure 4 It is a blind hole bottom morphology feature image corresponding to different laser processing time 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 It is a blind hole bottom morphology feature image corresponding to different laser processing time 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 image 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] Fig. 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 the technical solution more clear, the technical solution is further described in detail below 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 the technical solution.

[0044] Embodiment 1:

[0045] The present invention provides a laser processing method for a heterogeneous laminated component. 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) etc.)-carbon fiber reinforced composite material (CFRP) component, which is a sandwich structure, and the metal layer is located between two layers of carbon fiber reinforced composite materials. On this basis, as shown in 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 must be met:

[0047]

[0048] Wherein, 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 nth spiral n The following conditions must be met:

[0050]

[0051] In this embodiment, the starting end of the first spiral line is the starting point O of the spiral line center, so the distance between the starting end and the end of the first spiral line 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 located on the same straight line;

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

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

[0054] k=πr1 2 (1)

[0055] For the convenience of calculation, the area k is simplified to the circular area. 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 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] Therefore, by obtaining r n and Δd n The drawing of the spiral scanning trajectory can be realized, and the spacing between adjacent spiral lines (i.e., the distance Δd n ) gradually decreases from the inside to the outside, but the area between two adjacent spirals remains constant, so as to effectively improve 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, controlling the laser to output a laser beam, and making the laser beam start from the starting point O at the center of the spiral line, and scan along the spiral line scanning trajectory, on the upper CFRP surface of the heterogeneous laminated component, and controlling the focus of the laser beam to move downward after completing a circle of the spiral line scanning;

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

[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 0-600kHz 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 400-600kHz 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), in the first 5 seconds of laser processing, the upper layer of CFRP has not been completely removed. 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. 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 outwardly expanding, newly exposed ring-shaped metal layer will be continuously formed, and the exposed metal layer inside the ring-shaped metal layer will be laser ablated in the subsequent laser scanning process to form a black ablation area inside the ring-shaped metal layer.

[0073] Acquire an acoustic emission signal time domain curve, wherein the acoustic emission signal time domain curve 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 whole 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 bottom morphology feature image of the blind hole to determine the voltage value change rate (which may be the voltage value growth rate or the voltage value decrease rate) corresponding to when the metal layer is exposed, 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 change of voltage value on the time domain curve of acoustic emission signal, the time domain curve of acoustic emission signal 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 second 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 The voltage value fluctuates in a stable and fluctuating state, with the voltage value fluctuating between 0.25 and 0.3 V, and the voltage value growth rate and decline rate are both lower than 0.02 V / s. Finally, in stage III, the laser processes the dense metal layer (copper foil) and the action range gradually increases. Because the vibration amplitude of the dense metal layer is greater than that of CFRP, the voltage value increases with time, from 0.3 V at 5.5 seconds to 0.63 V at 9.5 seconds. The voltage value growth rate in this period is greater than 0.08 V / s, and the voltage value change in this stage is similar to that in the previous stage. Figure 4 In the figure, the morphological features of the bottom of the blind hole after laser processing for 6-9 seconds are basically corresponding;

[0076] 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, so 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 growth rate of the voltage value may not be 0.08V / s, so according to the material characteristics of different metal layers, in this embodiment, the value range of the voltage value growth rate threshold is determined to be [0.05V, 0.1V].

[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 morphological feature images of the blind hole at 1 second, 2.5 seconds, 5.5 seconds, and 9.5 seconds of laser processing, 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] A frequency and volume distribution curve of an acoustic emission signal is obtained, wherein the frequency and volume distribution curve includes the frequency of the acoustic emission signal 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 It can be seen from parts (a) and (b) that when the laser processing time T changes from 1s to 2.5s, the volume of the AE signal in the frequency band of 0-400kHz shows an overall downward trend. For example, the volume amplitude of the 60kHz frequency decreases from -23dB to -37dB, and the volume amplitude of the 350kHz frequency decreases from -30dB to -35dB. The volume amplitudes of the AE signals in the two frequency bands of 400-600kHz and 600-1000kHz are basically the same, indicating that the energy of the AE signal in this frequency band has almost no change. In 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 increasing 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 volume of the acoustic emission signal 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 increasing 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 has almost no change. In 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 to make holes, the spacing between the spiral lines is constant at d / 2n, such as Figure 8 As can be seen from parts (a) to (f) in the figure, there is only an annular metal layer (such as copper foil (Cu)) 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 to form a black area in the center. The edge area is still covered by 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, and the metal layer in the central area is not obviously 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 the uniform removal 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)), 783μm( Figure 8 (D) in the figure), the minimum exposed area of ​​the metal layer is 0.231 mm2 ( Figure 8 (A) in), the maximum is 0.481mm2( Figure 8 (D) in the figure, and the blind hole taper is 0.261 at the maximum and 0.113 at the minimum.

[0086] Therefore, the equal-area variable-pitch spiral scanning strategy in this embodiment can make the coverage area of ​​each circle of the spiral line 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 removal efficiency of the inner and outer circle areas similar during each layer of processing, thereby achieving uniform material removal in the processing area and avoiding the problem of severe energy accumulation in the central area and insufficient energy in the edge area, resulting in uneven material removal.

[0087] Embodiment 2:

[0088] This embodiment provides a laser processing device for implementing the laser processing method of the heterogeneous laminated component described in Embodiment 1, such as Fig. 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, which is connected to the laser processing unit 100, and is used to control the laser beam to start from the spiral center starting point O of the spiral scanning trajectory in step S1, and scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory, and control the focus of the laser beam to move downward after completing a circle of spiral scanning;

[0091] An acoustic emission signal acquisition device 300, which is connected to the control unit 200 and 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, which is connected to the control unit 200 and the acoustic signal acquisition device 300, and is used to determine whether the metal layer of the heterogeneous laminated component has been exposed according to the time domain curve and / or the frequency distribution curve, and when the metal layer is considered to be exposed, generate a control signal and send it to the control unit 200; wherein the process of determining whether the metal layer of the heterogeneous laminated component has been exposed according to 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, which can make the coverage area of ​​each spiral scanning track equal, forming a variable-pitch scanning track with sparse inside and dense outside, so as to effectively homogenize the energy distribution in the processing area, so that the laser energy distribution is balanced during each layer of laser scanning, and further make the material ablation efficiency of the inner circle and the outer circle area similar during each layer of processing, so as to achieve uniform material removal in the processing area, and avoid the problem that the material cannot be uniformly ablated due to serious energy accumulation in the central area and insufficient energy in the edge area;

[0095] At the same time, during the entire laser scanning process, the acoustic emission signal is acquired 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 contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes 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 made to start from the center starting point of the spiral line, scan along the spiral line scanning trajectory, and scan 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, the 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 according to 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: Wherein, 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 nth 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 line is the starting end of the nth spiral line.

4. The laser processing method for a heterogeneous laminated structure according to claim 1, wherein: Determining whether the metal layer of the heterogeneous laminated component has been exposed according to the time domain curve includes the following contents: 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 laminated component has been exposed according to the frequency distribution curve includes the following contents: 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, characterized in that: 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 component 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 start from the spiral center starting point of the spiral scanning trajectory and scan the upper surface of the heterogeneous laminated component along the spiral scanning trajectory, and control the focus of the laser beam to move downward after each spiral scanning. An acoustic emission signal acquisition device, which is connected to the control unit and 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; and a data processing unit connected to the control unit and the acoustic signal acquisition device, for determining whether the metal layer of the heterogeneous laminated component has been exposed according to the time domain curve and / or the frequency distribution curve, and generating a control signal when the metal layer is considered to have been exposed, and sending the control signal to the control unit; 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, characterized in that: The laser processing unit includes a nanosecond ultraviolet laser.

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