Method for detecting kerf width in laser cutting

Abstract

The invention relates to the technical field of laser processing, and discloses a method for detecting the width of a kerf in laser cutting, which comprises the following steps: controlling a phased array transducer to emit an ultrasonic beam, and enabling the ultrasonic beam to be coupled into an auxiliary gas flow coaxial with the laser beam; the auxiliary gas flow is used as an acoustic waveguide, and an ultrasonic beam is guided into the kerf of the workpiece; the phased array transducer receives an ultrasonic echo signal reflected by the inner wall of the kerf; and the control and data processing unit processes the echo signal and determines the width of the kerf according to the flight time of the ultrasonic wave. Global scanning and local focusing of the ultrasonic beam are further achieved through the phased array technology, the determined kerf width can be compared with a preset target value, and closed-loop control is conducted on laser cutting process parameters. According to the invention, high-precision and non-contact on-line measurement of the width of the narrow kerf can be realized, and the quality and consistency of laser cutting are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser processing, in particular to a method for detecting kerf width in laser cutting. BACKGROUND

[0002] Laser cutting is a processing technology that separates materials by locally heating, melting or vaporizing materials with high-energy-density laser beams and blowing away molten or vaporized materials with auxiliary gas. In the laser cutting process, the width of the kerf is one of the core technical indicators for evaluating cutting quality and processing accuracy, which directly affects the dimensional tolerance and fitting performance of the final formed workpiece. Therefore, accurate and real-time monitoring of the kerf width during laser cutting plays an important role in ensuring processing quality, optimizing process parameters and achieving automated production.

[0003] Existing kerf width detection techniques mainly measure the width after the cutting task is completed through offline methods. For example, optical microscopes, scanning electron microscopes or three-coordinate measuring machines are used to sample or full-size detect the completed workpiece. Although this kind of offline detection method can obtain high measurement accuracy, it cannot provide real-time feedback during the cutting process. When the cutting process parameters (such as laser power, cutting speed, gas pressure) fluctuate or the material properties are not uniform, the unqualified products that have been processed cannot be corrected in time, which leads to waste of materials and reduction of production efficiency. In addition, some high-precision detection requires cutting sampling of the workpiece, which is destructive detection and is not suitable for all production scenarios.

[0004] In order to realize online detection, some technical solutions attempt to use machine vision methods, that is, by setting a camera near the cutting head to capture images of the cutting area, and processing the images to extract the width information of the upper surface of the kerf. However, there are strong plasma light, metal slag splashing, smoke and other interference factors in the laser cutting site, which seriously affect the quality and stability of image acquisition. More importantly, this method can only obtain the surface width at the entrance of the kerf, and cannot measure the width change along the depth direction inside the kerf (i.e. kerf taper), so it cannot fully reflect the real geometric appearance of the kerf, and the process control information it can provide is limited.

[0005] Therefore, the present application proposes a method for detecting kerf width in laser cutting to solve the problems of the prior art. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a method for detecting kerf width in laser cutting, aiming to solve the technical problem that the prior art cannot perform real-time and non-contact measurement of the geometric size inside the kerf during the cutting process, thus making it difficult to effectively monitor and closed-loop control the cutting quality.

[0007] To solve the above technical problems, the present application provides a method for detecting the slit width in laser cutting, which can obtain the geometric size information inside the slit while cutting is being performed.

[0008] The technical solution provided by the present application specifically includes the following steps: S1. Emitting ultrasonic waves into the auxiliary gas flow coaxially sprayed with the laser beam via a transducer array integrated in the laser cutting nozzle, so that the auxiliary gas flow carries the ultrasonic waves; S2. Guiding the auxiliary gas flow into the slit formed on the workpiece by the laser beam, and the auxiliary gas flow acts as a propagation medium for the sound waves; S3. Receiving ultrasonic echo signals formed by reflection from the inner wall of the slit via the transducer array; the ultrasonic echo signals carry the position information of the inner wall of the slit; S4. Processing the ultrasonic echo signals to determine the width of the slit.

[0009] In a preferred embodiment, the transducer array is a phased array transducer. The step of emitting ultrasonic waves in the S1 step includes: applying independent excitation signals to each transducer unit in the phased array transducer through a control unit, and adjusting the amplitude and phase of each excitation signal to synthesize and form an ultrasonic beam with a preset spatial form.

[0010] In a specific embodiment, the step of forming an ultrasonic beam with a preset form includes: In a first working mode, the phased array transducer is controlled to emit a wide-beam ultrasonic wave. The wide-beam ultrasonic wave has a wide beam angle and can cover the entire depth range of the slit, performing global scanning of the slit to obtain a global ultrasonic echo signal.

[0011] Further, the detection method further includes: analyzing the global ultrasonic echo signal to identify a target region in the slit, such as a region where the slit width changes abnormally; and switching to a second working mode to control the phased array transducer to emit a focused ultrasonic beam to the identified target region, so that the acoustic energy is concentrated in the target region to obtain a focused ultrasonic echo signal with higher spatial resolution and signal-to-noise ratio.

[0012] Specifically, the step of emitting a focused ultrasonic beam to the target region is achieved by applying a set of pre-calculated time delays to the excitation signals of each transducer unit in the phased array transducer.

[0013] The step of applying a set of pre-computed time delays further comprises determining each time delay value in the set of time delays such that the ultrasound waves emitted by each transducer element arrive at the target focus point in the target region at the same time, thereby achieving constructive interference. For any jth transducer element, the required applied time delay can be determined by: wherein: is the time delay applied to the excitation signal of the jth transducer element; is the straight-line distance from the acoustic center of the jth transducer element to the target focus point; is the straight-line distance from a reference point to the target focus point, the reference point can be set as the geometric center of the phased array transducer; is the propagation speed of the ultrasound waves in the auxiliary gas medium. In one embodiment, the step S4 of processing the ultrasonic echo signal comprises: performing an inverse convolution operation on the ultrasonic echo signal and a pre-calibrated system point spread function. The system point spread function characterizes the response of the entire detection path to an ideal point reflector. Through the inverse convolution operation, the signal broadening effect caused by the system response can be eliminated, thereby obtaining the profile of the kerf width along the depth direction.

[0014] In another embodiment, when the global ultrasonic echo signal and the focused ultrasonic echo signal are acquired simultaneously, the determination of the kerf width in the step S4 is achieved by data fusion of the global ultrasonic echo signal and the focused ultrasonic echo signal. For example, the overall profile information provided by the global signal and the high-resolution local information provided by the focused signal are combined to generate a complete and high-precision kerf width profile.

[0015] In order to eliminate the fixed background noise caused by the nozzle structure, gas flow and electronic path, in one embodiment, the detection method further comprises a calibration step before the step S1: In the state that the laser beam is not turned on, ultrasonic waves are emitted into the auxiliary gas flow, and a baseline echo signal is received. The baseline echo signal can be subsequently used to calibrate the processing of the ultrasonic echo signal in the step S4, for example, to subtract the baseline signal from the subsequently acquired ultrasonic echo signal.

[0016] In addition, in order to realize real-time regulation of the laser cutting process, the detection method further comprises the following steps:

[0017] In addition, in order to realize real-time regulation of the laser cutting process, the detection method further comprises the following steps: ​​​The width information of the slit determined by the S4 step is output to the numerical control system of the laser cutting device in real time. The numerical control system adjusts at least one laser cutting process parameter, such as laser power, cutting speed or auxiliary gas pressure, according to the received width information, thereby forming a closed-loop control circuit.

[0018] The present application provides a method for detecting the slit width in laser cutting. It has the following advantages: 1. The present application integrates a transducer array into the laser cutting nozzle and uses the auxiliary gas coaxial with the laser beam as the sound wave propagation medium. The measurement process is integrated with the cutting process. This enables the geometric size information of the slit to be obtained while cutting is in progress, without interrupting production for offline detection, thereby providing a technical basis for real-time quality monitoring.

[0019] 2. The present application uses a phased array transducer to control the shape of the ultrasonic beam. In the first working mode, wide-beam ultrasonic waves are emitted to quickly scan the entire slit to grasp the overall profile. After identifying the target area, the second working mode is switched to, and focused ultrasonic beams are emitted to measure the area at high resolution, thereby obtaining accurate geometric information of the key parts of the slit.

[0020] 3. The present application outputs the real-time determined slit width data to the numerical control system of the laser cutting device. The numerical control system can dynamically adjust one or more process parameters such as laser power and cutting speed according to the feedback information. This enables the entire cutting process to be converted from open-loop execution to closed-loop control, which can actively compensate for the impact of interference factors on cutting quality, thereby improving the stability of the process and the yield. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the system structure of the present application; Figure 2 The figure is a schematic diagram of the ultrasonic beam emission and shaping principle of the present application; Figure 3 The figure is a schematic diagram of the echo signal processing flow of the present application; Figure 4 The figure is a complete flowchart of the detection and control of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] Reference is made to the accompanying drawings Figure 1 The system is configured to perform the detection method of the present invention.

[0024] In a specific embodiment, the system is deployed in a laser cutting machine. The laser cutting machine comprises a numerical control system and a laser cutting head controlled to move by the numerical control system. The detection function of the present invention is mainly realized by dedicated components integrated in the laser cutting head and external collaborative units.

[0025] Specifically, a laser cutting nozzle is installed at the end of the laser cutting head. A phased array transducer is integrated inside the laser cutting nozzle. The phased array transducer is arranged by an array of multiple independently controllable transducer elements, which can be arranged in a ring, a line or a two-dimensional surface array. The phased array transducer is positioned so that it can emit ultrasonic waves into the auxiliary gas jet emitted from the nozzle opening of the laser cutting nozzle.

[0026] The system further comprises a control and data processing unit. The control and data processing unit is electrically connected to the phased array transducer through a shielded cable, for sending excitation signals to it and receiving its returned echo signals.

[0027] The control and data processing unit functionally comprises a multi-channel signal generator, a data acquisition module, and a processor. The multi-channel signal generator is used to generate electrical excitation signals with specific timing and amplitude, and is applied to each transducer element of the phased array transducer. The data acquisition module is used to receive and digitize the echo electrical signals converted by each transducer element. The processor is used to perform subsequent signal processing, beamforming calculation, kerf width determination, and communication tasks with external devices.

[0028] The control and data processing unit also establishes a bidirectional communication connection with the numerical control system of the laser cutting machine. This connection enables the control and data processing unit to send the calculated kerf width information to the numerical control system in real time, and to receive instructions or status information from the numerical control system.

[0029] The working environment of the present invention is the processing site of laser cutting. In operation, the laser cutting head moves above the workpiece along the preset trajectory under the control of the numerical control system. The laser beam is emitted from the laser cutting head and focused on the workpiece surface through the central channel of the laser cutting nozzle, forming a kerf. At the same time, the auxiliary gas jet coaxial with the laser beam is emitted at high speed from the laser cutting nozzle and acts on the cutting area. In addition to performing the function of blowing away molten material, the auxiliary gas jet also serves as an acoustic coupling medium for the propagation of ultrasonic waves between the nozzle and the kerf in the present invention.

[0030] Reference is made to the accompanying drawings Figure 1 and the accompanying drawings Figure 2The S1 step of the present application, i.e. the step of emitting ultrasonic waves, starts from the control and data processing unit. Specifically, the processor in the unit calculates a set of electric excitation signal parameters required for driving the phased array transducer according to a preset detection mode (e.g. global scanning or focused scanning).

[0031] The multi-channel signal generator generates and outputs independent electric excitation signals for each transducer unit in the phased array transducer according to the parameters. For the jthtransducer unit, the electric excitation signal received by it can be expressed as: is time; is the instantaneous voltage applied to the jthtransducer unit; is the amplitude of the signal, and the emission energy of the unit can be weighted by adjusting is the center operating frequency of the ultrasonic wave; is the time delay applied to the signal, which is the core control variable for realizing beam deflection and focusing; is a window function, which is used to modulate the continuous sine wave into a pulsed signal with a specific duration and envelope shape.

[0032] The ultrasonic subwaves emitted by all N transducer units interfere with each other in space. By precisely adjusting the time delay and amplitude

[0033] of each signal, constructive interference of each subwave can be achieved at a specified direction and spatial position, while destructive interference is achieved in other areas. The superposition of such waves eventually synthesizes a unified ultrasonic beam with a specific direction, shape and focal length in front of the phased array transducer. This synthesized ultrasonic beam is directly coupled into the auxiliary gas flow flowing inside the laser cutting nozzle and ready to be sprayed. The auxiliary gas flow acts as an acoustic propagation medium, and its internal pressure, density and temperature determine the propagation speed of the ultrasonic wave. The high-speed flowing auxiliary gas flow carries the shaped ultrasonic beam out of the nozzle port and directs it to the cutting area on the workpiece.

[0034]

[0035] Refer to the attached​​​​​​​​​Figure 1 The auxiliary gas stream carrying the ultrasonic beam is ejected at high speed from the exit of the laser cutting nozzle and directly acts on the cutting area of the workpiece. The auxiliary gas stream is used in the laser cutting process to blow away the molten material generated by the laser beam, thereby forming a narrow slit on the workpiece.

[0036] In the S2 step of the present application, the auxiliary gas stream is endowed with another function: as an acoustic waveguide guiding the ultrasonic beam deep into the interior of the slit. Since the auxiliary gas stream has high pressure and momentum, it can penetrate and fill the entire internal space of the slit. The ultrasonic beam moving with the gas stream is thus effectively guided and transported to the entrance of the slit and continues to propagate along the depth direction.

[0037] The inner wall of the slit provides a lateral physical boundary for the propagation of acoustic waves. This structural constraint, combined with the fluid boundary formed by the speed and pressure gradient of the auxiliary gas stream itself, together binds the ultrasonic energy beam inside the slit, reducing the dissipation of acoustic energy to the surrounding environment, ensuring that sufficient acoustic energy can reach the bottom of the slit and interact with the entire inner wall profile.

[0038] It should be noted that the propagation speed of the ultrasonic wave in this moving medium is affected by the gas flow speed. For the ultrasonic wave propagating along the gas flow direction (i.e., downward propagation), its actual ground propagation speed is the sum of the acoustic speed in the gas and the gas flow speed . For the echo reflected from the inner wall of the slit against the gas flow direction (i.e., upward propagation), its actual ground propagation speed is the difference between the acoustic speed in the gas and the gas flow speed .

[0039] ; ; where: is the propagation speed of the ultrasonic wave along the gas flow direction; is the propagation speed of the ultrasonic wave against the gas flow direction; is the standard acoustic speed of the ultrasonic wave in the static auxiliary gas, which is determined by the type of gas, temperature, and pressure; is the average flow speed of the auxiliary gas stream in the slit.

[0040] The precise consideration of this speed change is the basis for accurately calculating the kerf width based on the time-of-flight of the echo signal in step S4. Through this guiding and propagation step, the present invention successfully transfers and establishes the ultrasonic measurement field, originally located at the nozzle, within the narrow kerf of the workpiece, far from the transducer.

[0041] See attached document Figure 1 In step S2, the ultrasonic beam, guided into the kerf of the workpiece, interacts with the inner wall of the kerf along its propagation path. Due to the significant acoustic impedance difference between the auxiliary gas flow, which serves as the sound wave propagation medium, and the solid workpiece material, most of the acoustic energy is reflected when the ultrasonic beam strikes the inner wall of the kerf, forming an ultrasonic echo carrying information about the spatial position of the inner wall of the kerf.

[0042] These ultrasonic echoes originate from various reflection points within the slit and propagate upwards against the direction of the auxiliary gas flow, with a propagation speed defined above. After propagating within the slits and nozzle channels, it finally reaches and acts on the receiving surface of the phased array transducer.

[0043] In the S3 receiving step, the phased array transducers operate in receive mode. When the returned ultrasonic echo pressure field acts on the surface of each transducer unit, based on the positive piezoelectric effect, the piezoelectric material of each transducer unit deforms due to alternating mechanical stress, generating a weak charge on its two electrodes. This causes each transducer unit to convert the received acoustic pressure signal into an independent analog voltage signal.

[0044] For the Each transducer unit outputs an instantaneous voltage signal. With the instantaneous sound pressure received The following relationship exists between them: ; in: For time; For the first The instantaneous echo voltage signal output by each transducer unit; To act on the first Instantaneous echo sound pressure on the surface of each transducer unit; For the first The electromechanical conversion coefficient or receiving sensitivity of each transducer unit.

[0045] Ultimately, all of the phased array transducers The transducer unit generates Independent analog echo voltage signals are transmitted in real time via shielded cables to the data acquisition module inside the control and data processing unit. The data acquisition module will then process these signals. The signal is amplified, filtered, and converted from analog to digital to form a digital echo signal data array that can be processed by the processor in the next step (S4).

[0046] See attached document Figure 1 The S4 processing step is performed within the control and data processing unit by its processor. The input to this step is the digital echo signal data array from each transducer unit of the phased array transducer, provided by the data acquisition module in step S3. The purpose of this step is to extract the geometric width information of the slit from these raw time-domain signals.

[0047] The fundamental principle of this invention for determining kerf width is based on ultrasonic time-of-flight measurement. The processor analyzes the digital echo signal to identify specific echo peaks formed by reflections from the inner wall of the kerf and accurately determines their total round-trip time. Total round trip time It includes the descending time of the ultrasonic beam from the surface of the phased array transducer, along the auxiliary gas flow, to a reflection point on the inner wall of the cut, and the ascending time of the echo returning from that reflection point to the transducer surface against the airflow.

[0048] Based on the propagation speed defined above, the processor can calculate the one-way physical distance from the transducer surface to the reflection point using the following formula. ; in: This is the straight-line distance from the transducer unit to the reflection point on the inner wall of the slit; This is the total round-trip time measured by the processor from the echo signal; The speed at which ultrasound propagates along the direction of airflow; This represents the speed at which ultrasound propagates against the direction of airflow.

[0049] By processing all the received echo data and combining it with the beamforming parameters used during transmission (such as beam pointing angle), the processor can reconstruct the spatial coordinates of a series of reflection points on the inner wall of the cut.

[0050] Ultimately, the width of the kerf is determined as the lateral distance between reconstructed coordinate points on the inner walls of two opposing kerfs in the same depth plane. By repeating this calculation at different depths of the kerf, a complete profile curve characterizing the kerf width as a function of depth can be obtained.

[0051] See attached document Figure 2In order to perform comprehensive inspection of the cut, the present invention adopts a dual-mode working strategy, which is controlled and executed by the control and data processing unit, including a first working mode (wide beam global scanning) and a second working mode (focused beam scanning).

[0052] The dual-mode working strategy aims to first use a wide beam to quickly acquire global contour information of the slit along its entire depth, and then use a focused beam to measure specific target areas where higher resolution data is required, based on this global information.

[0053] In the first operating mode, the processor of the control and data processing unit calculates and controls the multi-channel signal generator to apply a specific set of excitation signals to each transducer unit of the phased array transducer to form a wide-beam ultrasonic wave with a wide beam angle. This can be achieved by applying a zero value or a small linearly increasing time delay to each excitation signal, thereby making the synthesized beam unfocused or only slightly focused, ensuring that its acoustic energy can cover the entire depth range of the cut. The resulting return signal is the global ultrasonic echo signal.

[0054] After acquiring the global ultrasonic echo signal, the processor analyzes it to identify the target area within the slit. The identification can be based on a preset algorithm, for example, by detecting deviations in the echo signal amplitude or arrival time from a preset threshold to locate areas where the slit width exhibits abnormal changes.

[0055] After determining the target area, the system switches to the second operating mode. In this mode, the processor calculates a new set of time delays. The purpose is to concentrate ultrasonic energy onto one or more target focal points within a target area. By applying this set of time delays, the ultrasonic wavelets emitted by each transducer unit can be superimposed in phase when they reach the target focal point, thereby creating a sound pressure maximum at that point. (The last sentence appears to be incomplete and possibly refers to a different topic.) The time delay required for each transducer unit It can be determined by the following formula: ; in: To be applied to the first The time delay of the excitation signal for each transducer unit; For the first The straight-line distance from the acoustic center of each transducer unit to the target focal point; This is the straight-line distance from a reference point to the target focal point. The reference point can be set as the geometric center of the phased array transducer. The velocity of sound is the speed at which ultrasound propagates in the assist gas medium.

[0056] At the target focus point Place, by all The total sound pressure level synthesized by the transducer units It is the superposition of the sound pressures of each wavelet, and its complex amplitude can be expressed as: ; in: For the first The amplitude of the excitation signal for each transducer unit; For wave number, ; Angular frequency, ; For the first Each transducer unit to the focal point The distance.

[0057] Through precise control The value of ensures that the phase of the exponent term in the above formula is aligned at the focal point, thereby maximizing the sound pressure level. The amplitude of the ultrasound beam is used to form a focused ultrasound beam. The return signal obtained from this focused ultrasound beam is a focused ultrasound echo signal, which has higher spatial resolution and signal-to-noise ratio than the global ultrasound echo signal.

[0058] See attached document Figure 3 When the control and data processing unit receives the digital echo signal from the phased array transducer, its internal processor executes a series of algorithms to determine the width of the slit.

[0059] In one embodiment, to improve the accuracy of the measurement results, the processor first performs a deconvolution operation on the received raw echo signal. Raw echo signal It is not directly equivalent to the actual physical contour of the kerf, but rather the actual contour of the kerf. The impulse response of the entire detection system (including transducers, electronic pathways, and sound propagation paths), i.e., the system point spread function. The result of convolution. This relationship can be represented as: ; in: For time; The echo signal actually acquired by the system; An ideal echo signal to characterize the true contour of the cut; This is the system point spread function, which can be pre-calibrated by measuring a standard point reflection source under the same conditions; This represents the convolution operation.

[0060] In order to Recovery The processor performs a deconvolution operation on the above equation. One implementation is to perform it in the frequency domain, converting the time-domain convolution into a frequency-domain multiplication using a Fourier transform, and then performing the division operation. This process can be represented as: ; in: Represents the Fourier transform operator; This represents the inverse Fourier transform operator.

[0061] This deconvolution process eliminates signal broadening and distortion caused by system response, thereby obtaining a higher resolution contour signal that better reflects the true geometric features of the inner wall of the cut.

[0062] In another embodiment, when the system employs a dual-mode operating strategy and simultaneously acquires global ultrasound echo signals and focused ultrasound echo signals, the processor performs a data fusion step to generate the final slit width profile. First, the global and focused echo signals are processed separately (e.g., deconvolution) to obtain low-resolution global contour data and high-resolution local contour data of the target region.

[0063] Subsequently, the processor precisely registers and replaces the corresponding spatial segments in the global contour data with the high-resolution local contour data. This process ensures that the final output kerf profile retains the complete depth coverage provided by the global scan while also possessing the high-precision geometric details provided by the focused scan within the identified key target areas, thus forming a complete, multi-resolution kerf width dataset.

[0064] See attached document Figure 4 This section describes a preferred implementation process that includes calibration steps and closed-loop process control.

[0065] In a preferred embodiment, to eliminate fixed background noise generated by the laser cutting nozzle's own structure, the turbulence of the auxiliary gas flow, and the electronic pathways, the system first performs a calibration step before starting the laser cutting process. In this step, the laser beam is inactive, but the auxiliary gas flow is injected normally. The control and data processing unit controls the phased array transducer to emit ultrasonic waves and receives the resulting baseline echo signal. The signal is stored in the memory of the control and data processing unit.

[0066] In the subsequent S4 processing step, when the system acquires real-time ultrasonic echo signals containing suture information... At this time, the processor first performs a background noise subtraction operation to obtain a calibrated echo signal. This operation can be represented as: ; in: For time; This is the calibration echo signal after background noise subtraction; This refers to the raw echo signal acquired in real time during the cutting process; The baseline echo signal is stored in advance.

[0067] Use Subsequent width determination calculations of the signal can reduce the impact of fixed noise sources on the measurement results, thereby improving the signal-to-noise ratio of the measurement data.

[0068] The present invention further provides a closed-loop control process that integrates the above-described measurement method into the laser cutting process. This process is initiated when the laser cutting equipment begins cutting along a preset trajectory on the workpiece and is executed periodically.

[0069] In one loop, the control and data processing unit first executes the complete measurement and processing steps S1 to S4 to determine one or more width parameters of the cut at the current position, such as the width value at a specific depth. .

[0070] The processor then takes the measurement value With a target width value preset in memory Compare and calculate the width deviation. ; The processor depends on the width deviation The value is calculated based on a preset control algorithm to determine the adjustment amount of one or more laser cutting process parameters. For example, if the laser power needs to be adjusted, the new laser power setting value is... It can be determined by a proportional-integral (PI) controller.

[0071] Finally, the control and data processing unit will execute the calculated parameter adjustment instructions (e.g., setting the laser power to...). The command is sent to the CNC system of the laser cutting equipment via a communication interface. Upon receiving the command, the CNC system instantly updates its control output to the laser or motion axis, thereby dynamically adjusting the cutting process along the subsequent cutting path to make the kerf width approach the target width value. The continuous execution of this process constitutes a complete closed-loop control system.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting the kerf width in laser cutting, characterized in that, Includes the following steps: S1. Ultrasonic waves are emitted into the auxiliary gas flow that is coaxially ejected with the laser beam via a transducer array integrated in the laser cutting nozzle, thereby causing the auxiliary gas flow to carry ultrasonic waves. S2. Guide the auxiliary gas flow into the slit formed on the workpiece by the laser beam; S3. Receive the ultrasonic echo signal reflected from the inner wall of the cut via the transducer array; S4. Process the ultrasonic echo signal to determine the width of the slit.

2. The method for detecting the kerf width in laser cutting according to claim 1, characterized in that, The transducer array is a phased array transducer, and the step of emitting ultrasonic waves in step S1 includes: controlling the excitation signal of each transducer unit in the phased array transducer to form an ultrasonic beam of a preset shape.

3. The method for detecting the kerf width in laser cutting according to claim 2, characterized in that, The step of forming a preset ultrasonic beam includes: in a first working mode, controlling the phased array transducer to emit a wide-beam ultrasonic wave to perform a global scan of the cut to obtain a global ultrasonic echo signal.

4. The method for detecting the kerf width in laser cutting according to claim 3, characterized in that, The detection method further includes: analyzing the global ultrasonic echo signal to identify a target region within the cut; and in the second operating mode, controlling the phased array transducer to emit a focused ultrasonic beam to the target region to obtain a focused ultrasonic echo signal.

5. The method for detecting the kerf width in laser cutting according to claim 4, characterized in that, The step of emitting a focused ultrasonic beam to the target area includes: A set of pre-calculated time delays is applied to the excitation signals of each transducer unit in the phased array transducer.

6. The method for detecting the kerf width in laser cutting according to claim 5, characterized in that, The step of applying a set of pre-calculated time delays further includes: Each time delay in the set of time delays is determined based on the difference between the acoustic wave propagation path length from the corresponding transducer unit to the target focal point within the target area and the acoustic wave propagation path length from the reference point to the target focal point.

7. The method for detecting the kerf width in laser cutting according to claim 1, characterized in that, The step S4, which processes the ultrasonic echo signal, includes: The ultrasonic echo signal is deconvolved with a pre-calibrated system point spread function to obtain the profile of the slit width along the depth direction.

8. The method for detecting the kerf width in laser cutting according to claim 4, characterized in that, The width of the slit in step S4 is determined by fusing the global ultrasound echo signal and the focused ultrasound echo signal.

9. The method for detecting the kerf width in laser cutting according to claim 1, characterized in that, This detection method also requires prior to step S1. Including calibration steps: With the laser beam off, ultrasonic waves are emitted into the auxiliary gas flow and the resulting baseline echo signal is received, which is used to calibrate the processing of the ultrasonic echo signal in step S4.

10. The method for detecting the kerf width in laser cutting according to claim 1, characterized in that, The detection method also includes the following steps: The width of the kerf is output to the CNC system of the laser cutting equipment in real time for adjusting at least one laser cutting process parameter.

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