Vibration sensing for machining workpiece with liquid jet guided laser beam

Abstract

The invention relates to a device for machining a workpiece with a laser beam guided by a liquid jet. The device comprises: a nozzle for generating the liquid jet; at least one lens for coupling the laser beam into the liquid jet; and a housing surrounding at least the nozzle and having an aperture for providing the liquid jet onto the workpiece. A vibration sensor of the apparatus is attached to the housing and configured to measure at least a first vibration of the housing caused by machining the workpiece and / or a second vibration of the housing caused by the liquid jet. Further, a processor of the apparatus is configured to determine a first set of parameters associated with machining the workpiece and / or a second set of parameters associated with the liquid jet based on the first vibration and / or the second vibration.

Description

Technical Field

[0001] This invention relates to apparatus and methods for machining workpieces using a laser beam employed in and guided by a liquid jet. The invention provides apparatus and methods capable of sensing vibrations in the apparatus housing to derive parameters generally associated with the machining process of the apparatus, the liquid jet, and / or the workpiece. Background Technology

[0002] Liquid jet-guided laser processing devices are widely used in material removal applications across various industries, such as cutting, ablation, drilling, or marking. These devices offer high precision and speed, making them a common choice for many machining and manufacturing processes. The accuracy and quality of workpieces processed with liquid jet-guided laser beams depend on the proper functioning of the device. Any malfunction or deviation from expected performance can lead to reduced workpiece quality or damage, and may even damage the device itself.

[0003] Therefore, it would be beneficial to analyze the equipment parameters or the condition of the workpiece in order to detect any such faults or deviations in a timely manner. Summary of the Invention

[0004] The present invention and its solution are also based on the following considerations.

[0005] In the first method, an exemplary device for guiding laser processing with a liquid jet is equipped with an acoustic sensor for sensing ambient sound during device use. Based on the output signal of the acoustic sensor, the device can analyze, for example, the state or depth of the workpiece being processed, or whether the liquid jet is in contact with an object, in order to detect any violations in a timely manner.

[0006] For example, an acoustic sensor can be specifically designed to detect sound frequencies associated with material removal, where the detected sound can indicate normal operation of the device. However, if no sound in the expected frequency band is detected, the device can alert the operator to stop processing and investigate any problems. This exemplary device can also determine and optimize the device's operating parameters based on the detected sound, thereby improving the device's efficiency and accuracy.

[0007] However, it has been observed that ambient sound sensing using this method can be affected by ambient noise, making it challenging to distinguish the sound generated by processing with a liquid jet-guided laser beam from other background noise. Ambient sound sensing can also be affected by factors such as distance, damping of internal sound within the workpiece itself, atmospheric conditions, liquid splashes, and signal reflections, which can lead to signal quality degradation. Furthermore, ambient sound sensing may not be suitable for all types of workpieces or laser processing applications.

[0008] In view of the above, one objective is to provide an improved apparatus for machining workpieces with a liquid jet-guided laser beam, which does not have the aforementioned drawbacks. For example, one objective is to accurately and reliably determine one or more processing parameters of the apparatus, particularly parameters related to the workpiece machining process and / or the liquid jet. Based on this, one objective is to improve the processing efficiency and reliability of the apparatus. Another objective is to enable various machining assistance applications, such as penetration detection, impact protection, liquid jet quality monitoring, depth sensing during workpiece machining, monitoring machining efficiency, and / or optimizing the operating parameters of the apparatus.

[0009] These and other objectives are achieved by the solutions described in the independent claims. Advantageous implementation methods are described in the dependent claims.

[0010] A first aspect of the invention provides an apparatus for machining a workpiece with a laser beam guided by a liquid jet, the apparatus comprising: a nozzle configured to generate the liquid jet; at least one lens configured to couple the laser beam into the liquid jet; a housing at least surrounding the nozzle and having an aperture for providing the liquid jet to the workpiece; a vibration sensor attached to the housing; and a processor; wherein the vibration sensor is configured to measure at least a first vibration of the housing and / or a second vibration of the housing; wherein the first vibration is caused by machining the workpiece with the laser beam, and the second vibration is caused by the liquid jet; and wherein the processor is configured to determine a first set of parameters related to machining the workpiece and / or a second set of parameters related to the liquid jet based on the measurements of the first vibration and / or the second vibration.

[0011] The laser beam can, for example, have a laser power in the range of 1 W to 2000 W. The orifice of the nozzle can define the diameter of the liquid jet and can have a diameter of, for example, 10 µm to 200 µm. For example, the diameter of the liquid jet can be about 0.6 to 1 times the diameter of the orifice. The liquid jet can be a water jet, i.e., the liquid used by the device can be water or a mixture of water and chemicals. The pressure of the liquid jet can be in the range of 50 bar to 800 bar. The liquid jet can be layered. The housing can be or can include a coupling unit in which the nozzle is arranged and the laser beam is optically coupled to the liquid jet in the coupling unit. For this purpose, a lens is not necessarily required to be arranged in the coupling unit.

[0012] The liquid jet is configured to guide the laser beam. This means that the laser beam is guided entirely within the liquid jet by total internal reflection. Consequently, the laser is continuously reflected within the liquid by the walls of the liquid jet (i.e., the interface between the liquid and the surrounding atmosphere). This liquid-jet-guided laser beam differs from a system that uses both a laser beam and a liquid jet, but where the liquid jet does not guide the laser through total internal reflection. In that system, the laser beam is focused directly onto the workpiece through the liquid. In this system, the liquid does not guide the laser to the workpiece; rather, the laser beam simply "happens" to propagate through the relatively large liquid jet.

[0013] Because the vibration sensor is attached to the housing, it can accurately and reliably measure the vibration of the housing. The measurement is unaffected by ambient noise, distance, atmospheric conditions, and signal reflection. The vibration measured by the vibration sensor may originate from sound generated by machining a workpiece with a laser beam guided by a liquid jet and / or by the liquid jet itself. This sound can be transmitted to the housing via the liquid jet. For example, if an acoustic sensor for ambient sound sensing is used and placed near the device, at least some portion of the sound will be difficult to measure via airborne propagation. Compared to ambient sound sensing, the vibration sensor of the first aspect of the device is configured to perform directional listening to the sound of workpiece machining and / or the liquid jet.

[0014] Based on one or more sensed vibrations, the processor of the device is configured to determine different sets of parameters related to workpiece machining and / or fluid jetting. Each set of parameters may include one or more parameters. These parameters can be used by the processor to monitor the performance of the device, particularly the machining process and / or fluid jetting. The processor can also adjust the processing parameters and / or fluid jetting parameters accordingly to improve the efficiency of the device. The determined parameters can also enable the processor to perform various machining-aiding applications, such as sensing the penetration of a laser beam into a workpiece, or stopping machining in the event of penetration to reduce machining time or protect items or components positioned behind the workpiece, or monitoring the quality of the fluid jetting that indicates the quality of workpiece machining (e.g., laminar flow or laminar flow length of the fluid jet, spray, photoacoustic effects, etc.), or determining the depth of material removal in the workpiece, or determining the material removal rate of the workpiece material, or aligning the fluid jetting with an object, or similar applications.

[0015] It is worth noting that the housing on which the vibration sensor is mounted is a housing that directly surrounds the nozzle (e.g., the coupling unit), and this housing may not be, for example, the housing of a liquid jet guiding laser machine on which the device is mounted.

[0016] In summary, the present invention provides an improved device due to the vibration sensor mounted on the housing of the device, and due to the specific configuration of the vibration sensor and the processor.

[0017] In one implementation of the device, the vibration sensor is further configured to measure a third vibration and / or a fourth vibration; the third vibration is caused by photoacoustic sensing via the laser beam within the housing, and the fourth vibration is caused by movement and / or rotation of the housing; and the processor is configured to determine a third set of parameters associated with the device based on the measurement of the third vibration and / or the fourth vibration.

[0018] Photoacoustics can relate to the interaction between the laser beam and components or liquids located within the housing, or to the housing itself, which induces a third vibration. During workpiece machining, the movement and / or rotation of the housing can be controlled by the device's processor and / or computer numerical control (CNC) equipment. This third set of parameters can provide additional information to the processor, which can use this information to improve the device's efficiency and / or enable machining-aided applications.

[0019] In one implementation of the device, the first vibration is based on a first sound generated at the workpiece by processing the workpiece with the laser beam and coupled to the housing via the liquid jet and the liquid within the housing; and / or the second vibration is based on a second sound generated by the liquid jet and coupled to the housing via the liquid jet and the liquid within the housing.

[0020] Therefore, vibration sensors can detect sound transmitted by (and propagating within) a liquid jet, as well as sound transmitted, for example, by the liquid chamber of a housing, causing the housing to vibrate. This makes it possible to sense sound generated by workpiece machining and / or the liquid jet very accurately, thus facilitating the derivation of a set of parameters.

[0021] The first sound, causing the first vibration, can be generated through the laser ablation process of the workpiece material and travels as the first vibration through the liquid jet, then through the housing to reach the vibration sensor. The second sound, causing the second vibration, can be generated through the liquid jet contacting (impacting) the workpiece and travels as the second vibration through the liquid jet, then through the housing to reach the vibration sensor. Both the first and second vibrations are useful vibrations, and the vibration sensor can be configured to measure these vibrations, distinguish them from each other, and differentiate them from any other vibration. For example, the first vibration can be used to determine information related to laser ablation (as an example of parameters related to workpiece machining), while the second vibration can be used to determine information related to liquid jet contact with the workpiece (as an example of parameters related to the liquid jet). Surprisingly, it has been found that laser ablation of the workpiece material and liquid jet contact with the workpiece produce sounds of different frequencies.

[0022] According to the solution of the present invention, both the laser beam and the sound (which are ultimately measured as vibrations by a vibration sensor) of the laser beam are guided from the workpiece to the housing by a liquid jet.

[0023] In one implementation of the device, the first sound travels at a higher speed in the liquid jet than it travels at in a gaseous atmosphere (e.g., air). Similarly, the second sound travels at a higher speed in the liquid jet than it travels at in a gaseous atmosphere.

[0024] Because sound travels faster in liquids than in air, vibration sensors can be configured to measure sound over a shorter timeframe than it would take to measure sound in air—for example, a shorter timeframe than that used by ambient sound sensors. This speed difference stems from the different media through which sound propagates, such as water versus air. Sound typically travels faster in liquids (like water) than in gases (like air). This increased speed is due to the greater density of liquids, where molecules are closer together, thus facilitating faster sound wave transmission.

[0025] In one implementation, the device further includes a frequency filter arranged and configured to separate the first sound and / or the second sound traveling in the liquid jet from other sounds.

[0026] Both the first and second vibrations are useful vibrations, and they can be separated by using a frequency filter to remove other acoustic signals. Therefore, more accurate sensing of the first and / or second vibrations can be achieved, especially with less noise interference. Filtering using a frequency filter allows the vibration sensor to better distinguish between the information related to the liquid jet contacting the workpiece and the information related to the laser ablation of the workpiece.

[0027] Furthermore, frequency filters can also filter out (eliminate) all vibrations based on sound that is not propagated through the liquid jet. For example, a frequency filter can be configured to eliminate vibration noise collected from the ambient atmosphere. In this way, the vibration sensor can measure only vibrations originating from sound transmitted through the liquid jet, thereby accurately collecting the desired information. In summary, a frequency filter can have two functions: (1) distinguishing between first and second vibrations, and (2) eliminating any vibrations from other sound sources or transmission methods.

[0028] In one implementation of the device, the laser beam is pulsed; and the vibration sensor is configured to measure the occurrence of the first vibration within a time period shorter than the time delay between two consecutive laser pulses of the pulsed laser beam.

[0029] Therefore, vibration can be attributed to a single laser pulse or to a number of laser pulses. The correlation between vibration and (one or more) laser pulses can determine specific parameters, such as the length of the liquid jet, and thus the processing depth.

[0030] In one implementation of the device, the laser beam is pulsed; and the processor is configured to determine the time difference between a first time when a specific laser pulse of the laser beam is generated and a second time when the associated first vibration is measured by the vibration sensor.

[0031] In one implementation of the device, the processor is configured to calculate, based on the time difference, the distance between the nozzle and the incident point of the laser beam on the workpiece, and / or the distance between the hole and the incident point.

[0032] Therefore, the processor can calculate the laser pulse time and the arrival time of the sound generated by the laser pulse and causing vibration, and then use the time of flight (time difference) to determine the distance to the liquid jet contact point.

[0033] In one implementation of the device, the vibration sensor is attached to and in direct contact with the outer surface of the housing, or attached to an adapter mounted on the outer surface of the housing.

[0034] Therefore, the vibration sensor can accurately measure the vibration of the housing, and / or can also be easily removed and reattached.

[0035] In one implementation of the device, the housing includes a first portion and a second portion, the first portion being removably attached to the second portion; the second portion of the housing includes the at least one lens; the first portion of the housing includes the nozzle and a liquid chamber located above the nozzle; and the vibration sensor is disposed at the first portion of the housing on the liquid chamber above the nozzle.

[0036] The first part can be the aforementioned coupling unit of the device, in which the laser and the liquid jet are coupled, i.e., the laser beam is inserted into the liquid jet, and thus the laser beam is guided in the liquid jet by total internal reflection. The vibration sensor can be a contact sensor that contacts the outer or inner wall of the liquid chamber (e.g., a water chamber) in the coupling unit. Because the vibration sensor is very close to the liquid and the sound that causes the housing to vibrate is transmitted mainly through the liquid (jet), accurate and virtually noise-free sensing is achieved.

[0037] In one implementation of the apparatus, at least one parameter in the first parameter set indicates one or more of the following: the material type of the workpiece; the material removal rate or material removal speed of removing workpiece material by processing the workpiece with the laser beam; and whether the laser beam has penetrated the workpiece.

[0038] In one implementation of the device, the processor is configured to determine whether the liquid jet contacts the workpiece based on whether the vibration sensor measures the first vibration.

[0039] In one implementation of the device, at least one parameter in the second parameter set indicates one or more of the following: the jet quality of the liquid jet and / or the laminar length of the liquid jet; the flow characteristics of the liquid jet; whether the laser beam impacts the nozzle; whether the liquid jet contacts the edge of a collision object arranged near the workpiece or contacts the workpiece itself.

[0040] This concept of sensing (also known as listening) whether the liquid jet is in contact with the workpiece, whether the liquid jet is in a free state, or whether the liquid jet has penetrated the workpiece is very helpful for controlling the workpiece machining process and achieving accurate machining results. Using a collision object, the processor can be configured to detect the position and / or angle of the liquid jet.

[0041] In one implementation, the apparatus further includes: an acoustic transducer arranged and configured to transmit sound waves through the liquid jet onto the workpiece; wherein the vibration sensor is further configured to measure a third vibration caused by the sound waves being reflected from the workpiece back into the housing through the liquid jet.

[0042] Therefore, the device is also capable of actively transmitting sound waves and sensing their reflections, in order to measure, for example, the time of flight of the sound waves and determine the corresponding distance.

[0043] In one implementation, the apparatus further includes: one or more photoelectric sensors, each configured to detect a first radiation or a second radiation; wherein the first radiation is caused by processing the workpiece with the laser beam, and the second radiation is caused by guiding the laser beam in the liquid jet or by processing the workpiece with the laser beam; wherein the first radiation includes at least one of: laser light reflected from the workpiece; and secondary radiation emitted by a portion of the workpiece processed with the laser beam; and wherein the processor is configured to further determine a first set of parameters and / or a second set of parameters based on measurements of the first radiation and / or the second radiation.

[0044] The additional radiation signal allows the processor to determine the parameters of each parameter set with even better accuracy and reliability.

[0045] In one implementation of the device, the second radiation includes at least one of the following: secondary radiation generated by the scattering (e.g., Raman scattering) of the laser beam in the liquid jet; laser light from the laser beam scattered in the liquid jet; and fluorescence of the liquid in the liquid jet induced by the laser beam; secondary processing light with a wavelength different from that of the laser beam, such as thermal radiation or infrared radiation.

[0046] In one implementation of the device, the processor is further configured to: fuse the output signals of the vibration sensor and the one or more photoelectric sensors, wherein the output signals are generated based on the measured first vibration and / or second vibration and the measured first radiation and / or second radiation; and determine the first parameter set and / or the second parameter set based on the fused output signals.

[0047] In one implementation of the device, the processor includes a trained model or a rule-based algorithm and is configured to input the output signal into the trained model or the rule-based algorithm; and the trained model is configured to fuse the output signal and determine the first parameter set and / or the second parameter set based on the fused output signal.

[0048] Rule-based algorithms can be installed in a processor and executed by the processor. The trained model can be a trained neural network, such as a convolutional neural network (CNN). The neural network can be a deep neural network (DNN). Using a trained model can improve the accuracy of the detected parameters and automatically optimize various operating parameters of the device to achieve improved processing results.

[0049] In one implementation of the device, the processor is further configured to adjust at least one operating parameter of the laser beam and / or the liquid jet based on a determined first parameter set and / or second parameter set.

[0050] A second aspect of the invention provides a method for machining a workpiece with a laser beam guided by a liquid jet, the method comprising: generating a liquid jet using a nozzle; coupling the laser beam into the liquid jet using at least one lens; measuring at least a first vibration and / or a second vibration of a housing surrounding the nozzle, wherein the first vibration is caused by machining the workpiece with the laser beam and the second vibration is caused by the liquid jet; and determining a first set of parameters related to machining the workpiece and / or a second set of parameters related to the liquid jet based on the measurements of the first vibration and / or the second vibration.

[0051] In one implementation, the method further includes: modifying at least one operating parameter of the laser beam and / or the liquid jet based on the determined first parameter set and / or second parameter set.

[0052] The second method achieves the same advantages as the first method and can be extended by various implementations corresponding to the implementation of the first method.

[0053] A third aspect of the invention provides a computer program comprising instructions for controlling a device according to a first aspect when a processor executes the instructions, or for causing the device to perform a method according to a second aspect when a computer executes the instructions. Attached Figure Description

[0054] The above aspects and implementations are explained in the following description of embodiments with reference to the accompanying drawings:

[0055] Figure 1 An exemplary device according to the present invention is shown.

[0056] Figure 2 An exemplary device having a two-part housing according to the present invention is shown.

[0057] Figure 3 The working principle of the device according to the present invention is shown.

[0058] Figure 4 An exemplary device according to the present invention has additional components for vibration sensing and optical sensing.

[0059] Figure 5 An exemplary processor of an apparatus capable of signal fusion according to the present invention is shown.

[0060] Figure 6 An exemplary device with an acoustic transducer according to the present invention is shown.

[0061] Figure 7 The method according to the present invention is shown.

[0062] Figure 8 An apparatus according to the invention is shown within a liquid jet-guided laser machine.

[0063] Figure 9 An exemplary algorithm for signal fusion using a rule-based algorithm is shown, which can be executed by a processor of a device according to the invention. Detailed Implementation

[0064] Figure 1A basic implementation of the device 10 according to the invention is shown. The device 10 is configured to process a workpiece 11 with a laser beam 12, wherein the laser beam 13 is in and guided by a liquid jet 13, for example, in and guided by a water jet. The workpiece 11 may be made of one or more materials, including, for example, metals, ceramics, diamond, semiconductors, carbides, alloys, superalloys, or superhard materials. The workpiece 11 is not part of the device 10; however, the workpiece 11 may be positioned on a processing surface, which may or may not be part of the device 10. In either case, the device 10 may be arranged such that it can process the workpiece 11 disposed on the processing surface. The device 10 may also control the movement of the processing surface in up to three dimensions, or it may control the movement of the liquid jet-guided laser beam relative to the workpiece 11, for example, by moving and / or rotating the nozzle or housing that generates the liquid jet 13.

[0065] The device 10 includes a nozzle 14, at least one lens 15, and a housing 16. The housing 16 at least surrounds the nozzle 14 and optionally also surrounds at least one lens 15. The housing 16 has an aperture 19 for ejecting a liquid jet 13 and delivering it onto a workpiece 11. Liquid can be supplied to the nozzle 14 through a liquid supply section, which may include a channel through the housing 16, to form the liquid jet 13. A gas supply section may also be provided, which may include another channel through the housing 16, and a protective gas, such as helium, can be supplied into the housing 16 through the gas supply section, particularly to the area traversed by the generated fluid jet 13 after exiting the nozzle 14. Here, the protective gas can protectively surround the fluid jet 13 before it exits the housing 16.

[0066] At least one lens 15 is configured to couple the laser beam 12 into the liquid jet 13; for example, at least one lens 15 can focus the laser beam 12 into the nozzle 14. At least one lens 15 can be a single lens or a group of lenses. At least one lens 15 can be disposed inside or outside the housing 16. Preferably, at least one lens 15 is separated from the liquid within the housing 16, which can be achieved through optical windows that prevent contact between the lens 15 and the liquid and / or through a multi-chamber housing.

[0067] The device 10 also includes a vibration sensor 17 and a processor 18. The vibration sensor 17 is attached to the housing 16, for example, externally (as shown) or internally. The vibration sensor 17 can be directly attached to the housing, or indirectly attached to the housing, for example, using an adapter. The processor 18 can be disposed externally to the housing 16.

[0068] Vibration sensor 17 is configured to measure vibrations of housing 16. Vibration sensor 17 is specifically configured to measure at least a first vibration and / or a second vibration of housing 16. The first vibration is caused by machining workpiece 11 with laser beam 12, and the second vibration is caused by liquid jet 13. Vibration sensor 17 can also be configured to measure additional vibrations, such as a third and / or fourth vibration of housing 16. For example, the third vibration may be caused by photoacoustic sensing through laser beam 12 within housing 16. For example, the fourth vibration may be caused by movement and / or rotation of housing 16. Each vibration is associated with a frequency or frequency range, where different vibrations have different frequencies or frequency ranges. Vibration sensor 17 can be adapted to detect vibrations specifically at or within these frequencies. Vibration sensor 17 can output a signal 17s that reflects or indicates the detected vibration.

[0069] Processor 18 is configured to determine a first parameter set p1 related to the workpiece 11 and / or a second parameter set p2 related to the liquid jet 13 based on measurements of a first vibration and / or a second vibration. Processor 18 can receive an output signal 17s from vibration sensor 17, which can indicate the result of vibration measurement by vibration sensor 17. Signal 17s can indicate that the first vibration has been measured, or it can indicate whether the first vibration has been measured or not. Processor 18 can be configured to determine the first parameter set p1 based on the occurrence and / or absence of the first vibration. Furthermore, processor 18 can be configured to determine the second parameter set p2 based on the occurrence and / or absence of the second vibration. Processor 18 can also be configured to determine additional parameter sets, such as a third parameter set related to device 10, for example, based on the occurrence of a third and / or fourth vibration or the absence of any one or both of these vibrations.

[0070] By detecting the corresponding vibrations, device 10 can determine certain process conditions for machining workpiece 11 and can use these process conditions for different optimizations in machining-aided applications (such as efficiency optimization, penetration detection, or other applications as described above). Device 10 can perform depth sensing to determine the coordinates of the contact point between the liquid jet 13 and the workpiece 11, which may be within a hole or recess in the workpiece 11. For example, device 10 can determine the timing of vibration occurrence for this purpose. For example, if the laser beam 12 is pulsed, processor 18 can determine the time difference between the first time when a specific laser pulse of laser beam 12 is generated and the second time when the associated vibration occurs, as measured by vibration sensor 17. However, device 10 can also sense vibration over time and correlate it with pulse parameters (such as pulse width, pulse duration, pulse power, etc.) within that time.

[0071] It is worth noting that the vibration of the housing 16 may be caused by different kinds of sound, such as the sound generated at the workpiece 11 by machining the workpiece 11 with the laser beam 12, or the sound generated by the liquid jet 13 itself. These sounds can be transmitted to the housing 16 through the liquid jet 13 and also through the liquid located within the housing 16, causing the housing 16 to vibrate. For example, if the vibration sensor 17 is attached to the outside of the housing, some of these sound components can also be transmitted to the vibration sensor 17 through the air path. However, the liquid path that transmits the sound to the housing 16 is generally of better quality.

[0072] Processor 18 may include processing circuitry (not shown) configured to perform, conduct, or initiate various operations of processor 18 as described herein. The processing circuitry may include hardware and / or may be controlled by software. The hardware may include analog or digital circuitry, or both. Digital circuitry may include components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors. Processor 18 may also include memory circuitry storing one or more instructions executable by the processing circuitry, particularly under software control. For example, the memory circuitry may include a non-transitory storage medium storing executable software code that, when executed by the processing circuitry, enables various operations of processor 18 to be performed.

[0073] Figure 2 An implementation of the device 10 according to the invention is shown, which is based on Figure 1 Based on the device 10 shown. Figure 1 and Figure 2 The same components in the figure are marked with the same reference numerals and have the same function, so they do not need to be described again.

[0074] like Figure 2As shown, the housing 16 of the device 10 includes a first portion 16a and a second portion 16b. The first portion 16a is removably attached to the second portion 16b, for example, by a mechanical or magnetic connection. The second portion 16b of the housing 16 includes at least one lens 15, and the first portion 16a of the housing 16 includes a nozzle 14 and a liquid chamber 21 formed above the nozzle 14. The first portion 16a can be the aforementioned coupling unit of the device 10, since the laser beam 12 is coupled into the liquid jet 13 in the first portion 16a. When the first portion 16a and the second portion 16b are attached to each other, they can be separated from each other by their housing walls 22, which may each include an optical window, or they may be transparent walls 22. The liquid chamber 21 may be defined in the first portion 16a by an inner wall 23, which may include a window 25 for coupling the laser beam 12 into the liquid chamber 21 and the nozzle 14. It is worth noting that the housing 16 may also include more than two portions 16a, 16b.

[0075] exist Figure 2 In the implementation of the illustrated device 10, the vibration sensor 17 is exemplaryly arranged on the outer surface of the housing 16, specifically, on the exterior of the first portion 16a of the housing 16. However, the vibration sensor 17 may also be located on the outer wall of the liquid chamber 21 above the nozzle 14, i.e., inside the first portion 16a of the housing 16. The vibration sensor 17 may also be arranged on the inner surface of the housing 16, specifically, inside the first portion 16a of the housing 16. The vibration sensor 17 may be an acoustic microphone. The sound measuring the vibrations of the housing 16 that cause vibrations may originate from its original sound source, reaching the housing 16 and the sensor 17 via the liquid jet 13 and the liquid chamber 21.

[0076] Figure 3 The working principle of the device 10 of the present invention is shown, as well as exemplary sounds and vibrations that the vibration sensor 17 of the device 10 can generate and detect.

[0077] For example, a first sound 32 can be generated at workpiece 11 by processing workpiece 11 with laser beam 12. Specifically, the first sound 32 can be generated by laser beam 12 when laser beam 12 cuts or drills into workpiece 11, thereby generating plasma 34 in the pit 35 formed in workpiece 11. The first sound 21 can be a sound wave (shock wave) generated on workpiece 11 by laser pulses of laser beam 12. The sound wave can travel at least partially through liquid jet 13 and liquid within housing 16, and can be coupled to housing 16, wherein vibration sensor 17 is configured to measure it as a first vibration of housing 16. As another example, a second sound 33 can be generated by liquid jet 13 itself, wherein similarly, the second sound can be coupled at least partially through liquid jet 13 and liquid within housing 16 to housing 16, wherein vibration sensor 17 is configured to measure it as a second vibration of housing 16.

[0078] For example, processor 18 can determine the time of flight, and in particular, the time difference between the arrival of the laser pulse of laser beam 12 and the arrival of the associated sound (i.e., the occurrence of vibration) measured by vibration sensor 17. In other words, processor 18 can be configured to determine the time difference between the first time when a specific laser pulse of laser beam 12 is generated and the associated second time when the corresponding vibration occurs, as measured by vibration sensor 17. In this way, for example, the depth of the pit 35 in workpiece 11 can be estimated.

[0079] Figure 3 Also shown is a moving axis controller 31 (e.g., a CNC device), which can, for example, move the workpiece 11 or move the machining surface holding the workpiece 31 under the control of the processor 18.

[0080] Figure 4 One implementation of device 10 is shown, which is based on Figure 1 Based on the implementation of the device 10 shown. Figure 1 and Figure 4 The same components in the figure are marked with the same reference numerals and have the same function, so they do not need to be described again.

[0081] Figure 4 The device 10 may also include a frequency filter 41, which is configured to direct the first sound 32 and / or the second sound 33 (e.g., as shown in the diagram) that travels in the liquid jet 13. Figure 3(As shown) to separate from other sounds, or to separate the first vibration and / or the second vibration from other vibrations of the housing 16. Frequency filter 41 can filter out certain sound or vibration frequencies and allow certain other sound or vibration frequencies of interest to pass through. For example, frequency filter 41 can be arranged in the signal path of signal 17s, such as on a signal cable, to filter out certain frequencies from electronic signal 17s by electronic filtering. In this case, a clean signal 17c (as shown) is generated based on signal 17s. Alternatively, frequency filter 41 can be integrated into processor 18 for software filtering of signal 17s.

[0082] In addition, such as Figure 4 It is also shown that the device 10 may include an adapter 42, which allows the vibration sensor 17 to be easily attached to the housing 16, and similarly allows it to be easily removed. In this case, the adapter 42 can be attached to the outer surface of the housing 16 in direct contact, and the vibration sensor 17 is attached to the adapter 42. This is similar to, for example... Figure 1 The vibration sensor 17 shown is directly attached to the outer surface of the housing 16, or as... Figure 2 The vibration sensor 17 shown is different from the case where it is directly attached to the outer surface of the first portion 16a of the housing 16. Attachment to the inner surface of the vibration sensor 17 can also be accomplished via the adapter 42. Furthermore, a frequency filter 41 can be integrated into the adapter 42 to filter the signal (vibration) before the vibration sensor 17 senses it.

[0083] like Figure 4 Additionally, in addition to the frequency filter 41, the device 10 may also include an amplifier 45, which is also included in the signal path of the signal 17s, for example, on the signal cable. This amplifier 45 amplifies the signal amplitude to a voltage that can be more easily measured by the processor 18.

[0084] Figure 4 It is also shown that device 10 may include one or more photoelectric sensors or detectors, such as one or both of photoelectric sensors 43 and / or 44, wherein the first photoelectric sensor 43 is configured to detect a first radiation and the second photoelectric sensor 44 is configured to detect a second radiation. The first photoelectric sensor may be a sensor chip included in the housing (or housing 16) of device 10. The second photoelectric sensor 44 may be a camera 44 disposed outside the housing 16, for example, near the workpiece 11. For example, the first radiation may be caused by processing the workpiece 11 with a laser beam 12. The first radiation may be secondary radiation (i.e., not laser) generated by processing the workpiece 11, for example by... Figure 3The plasma 34 shown is emitted. Alternatively, the first radiation can also be reflected laser light. For example, the second radiation can be caused by a laser beam 12 guided in the liquid jet 13. For example, the second radiation can be secondary radiation (not laser beam 13) generated by (e.g., Raman) scattering of laser beam 12 in the liquid jet 13. Alternatively, the second radiation can also be laser light from laser beam 12 scattered in the liquid jet 13.

[0085] At least one of photoelectric sensors 43 and 44, for example Figure 4 The first photoelectric sensor 43 can be arranged such that it can receive the first radiation through the liquid. That is, the first radiation propagates through and away from the workpiece 11 in the liquid jet 13, and optionally through at least one lens 15. In other words, the first radiation can be guided in the liquid jet 13 similarly to a laser beam 12. The device 10 may also include one or more spectral separation units, wherein each spectral separation unit (e.g., a filter) can be configured to separate only the electromagnetic radiation of interest to the first photoelectric sensor 43 or the second photoelectric sensor 44, including either the first radiation or the second radiation.

[0086] Figure 4 The processor 18 of the device 10 can also be configured to take into account the output signals 43s and / or 44s provided by the photoelectric sensors 43 and / or 44 when determining the first parameter set p1 and / or the second parameter set p2. These signals 43s and 44s can indicate the occurrence of the first radiation and / or the second radiation, respectively.

[0087] Figure 5 An exemplary processor 18 of the device 10 is shown. Figure 5 The processor 18 is configured to perform signal fusion. That is, as an example, the processor 18 can process the output signal 17s (or signal 17c, if signal 17s is frequency filtered) of the vibration sensor 17 and the output signals 43s and 44s (see [link to relevant documentation]) of the first photoelectric sensor 43 and the second photoelectric sensor 44, respectively. Figure 4 The fusion is performed. Fusion can mean calculating a fused signal based on the output signals 17s, 43s, and 44s, for example, by combining these output signals and optionally weighting them. As mentioned above, the output signal 17s (or 17c) can be generated based on a first vibration and / or a second vibration, and the output signals 43s and 44s can be generated based on a first radiation and / or a second radiation. The processor 18 can, for example, determine a first parameter set p1 and / or a second parameter set p2 based on the fused output signals 17s, 43s, and 44s.

[0088] To this end, processor 18 may include rule-based algorithms and / or may be adapted to execute rule-based algorithms that use different kinds of signal characteristics or thresholding to fuse decisions based on output signals 17s (or 17c), 43s, and 44s. An example is... Figure 9 It is shown in the figure and explained below.

[0089] Alternatively, processor 18 may include and employ a trained model 51 (as shown), such as a neural network. The trained model 51 may be configured to receive output signals 17s (or signal 17c, if signal 17s is frequency-filtered), 43s, and 44s. The trained model 51 may be trained to fuse output signals 17s (or 17c), 43s, and 44s, and may be trained to determine a first parameter set p1 and / or a second parameter set p2 based on the fusion result. The trained model 51 may have been trained in a supervised manner, for example, by having the trained model 51 determine a known set of parameters based on the output signals, and then correcting the trained model 51. The trained model 51 may also be trained in an unsupervised manner. During use of device 10, the trained model may be further trained.

[0090] Figure 6 One implementation of device 10 is shown, which is based on Figure 1 Based on the implementation of the device 10 shown. Figure 1 and Figure 6 The same components in the figure are marked with the same reference numerals and have the same function, so they do not need to be described again.

[0091] Figure 6 Another implementation is shown in which the vibration sensor 17 is placed inside the liquid chamber 21 of the housing 16 (e.g., as shown in the diagram). Figure 2 (Within the first part 16a shown). The vibration sensor 17 can be configured to measure vibrations of the liquid coupled to the housing 16. Since the vibration sensor 17 is inside the housing 16 in this implementation, external ambient noise can be shielded.

[0092] like Figure 6 It is also shown that, in one implementation, the device 10 may further include an acoustic transducer 61, which is arranged and configured to transmit sound waves 62 through a liquid jet 13 (such that the sound waves 62 are guided in the liquid jet 13) to the workpiece 11. When processing the workpiece ( Figure 6When (not shown), the sound wave 62 can travel along a path similar to that of the laser beam 12. The sound wave 62 and the laser beam 12 can be provided alternately or simultaneously. The vibration sensor 17 can also be configured to measure a third vibration caused by the sound wave 62 being reflected back from the workpiece 11 into the housing 16 by the liquid jet 13 and guided by the liquid jet 13. Using the acoustic transducer 61, the processor 18 can determine the time of flight of the sound wave 62 and, based on the time of flight, derive the length of the fluid jet 12, or the distance between the housing 16 and the workpiece 11, or similar geometric parameters.

[0093] It is worth noting that, Figures 2-5 Additional features of the various (optional) implementations of the device 10 shown can be added individually or in any combination. Figure 1 The basic implementation of the device 10 shown is characterized by the following features.

[0094] Each of the shown implementations of device 10 ( Figures 1-6 The device may include a laser source and a laser controller for controlling the laser source. In this case, the laser source is configured to supply laser light via laser beam 12. The laser source may also be an external device not included in the device 10 but used, for example, to supply laser light to the laser supply port of the device 10 via optical fiber. In the device 10, the laser beam 12 may be guided, for example, by a beam splitter toward a lens 15, which is used to couple the laser beam 12 into the fluid jet 13.

[0095] Each of the shown implementations of device 10 ( Figures 1-6 The fluid supply controller may alternatively or additionally include one or more peripheral devices, such as a fluid supply controller (which may optionally be integrated with the fluid pump), a gas supply controller (e.g., a gas supply controller for protectively surrounding the fluid jet 12), and a moving axis controller 31 (see [link to relevant documentation]). Figure 3 or Figure 8 (e.g., CNC equipment) The moving axis controller can be configured to move the machining surface on which the workpiece 11 is placed in the vertical x, y, and z directions and / or the rotational a, b, and c directions, or alternatively move the workpiece 11 itself.

[0096] Processor 18 can be configured to provide corresponding command signals to different peripheral devices of device 10. For example, processor 18 can be a controller capable of controlling a laser controller, a fluid supply controller, a gas supply controller, and / or a movement axis controller via corresponding signals. Processor 18 can be configured to control these devices based on a first set of parameters p1 associated with the workpiece 11 and / or a second set of parameters p2 associated with the liquid jet 13 and / or a third set of parameters associated with device 10. Processor 18 can also be configured to adjust at least one operating parameter of laser beam 12 and / or liquid jet 13, for example, by correspondingly controlling one or more of these devices based on the first set of parameters, the second set of parameters, and / or the third set of parameters.

[0097] Figure 7 A method 70 of the present invention for machining a workpiece 11 with a laser beam 12 guided by a liquid jet 13 is illustrated. Method 70 includes: step 71, generating a liquid jet using a nozzle; and step 72, coupling the laser beam 12 into the liquid jet 13 using at least one lens 15. Method 70 further includes: step 73, measuring at least a first vibration and / or a second vibration of at least a housing 16 surrounding the nozzle 14. The first vibration is caused by machining the workpiece 11 with the laser beam 12, and the second vibration is caused by the liquid jet 13. Method 70 may then include: step 74, determining a first set of parameters related to machining the workpiece 11 with the laser beam 12 and / or a second set of parameters related to the liquid jet 13 based on the measurements of the first and / or second vibrations.

[0098] Figure 8 One implementation of device 10 is shown, which is based on Figure 1 Based on the implementation of the device 10 shown. Figure 1 and Figure 8 The same components in the figure are marked with the same reference numerals and have the same function, so they do not need to be described again.

[0099] like Figure 8 As shown, the device 10 can be disposed within a liquid jet-guided laser machine, wherein the liquid jet-guided laser machine includes a machine housing 82 (also referred to as an outer casing). The machine housing 82 is distinctly different from the housing 16 on which the vibration sensor 16 is housed. The housing 16 can be referred to as the inner housing 16 of the laser machine (because it is within the machine housing 82) and is, for example, a coupling unit that couples the laser beam 12 into the liquid jet 13. Specifically, the housing 16 is a shell directly surrounding the nozzle 14 and optionally surrounding the lens 15 (e.g., in the case of the first portion 16a and the second portion 16b of the housing 16, as...). Figure 8 (As shown). In other words, within housing 16 or the first portion 16a of housing 16, nozzle 14 is not surrounded by another housing or shell. Figure 8It is also shown that the liquid chamber 21 may be located within the housing 16 or the first portion 16a of the housing 16.

[0100] Figure 8 It is also shown that the device 10 may include a collision object 81, wherein the collision object 81 may be arranged adjacent to and / or near the workpiece 11. At least one parameter in the second parameter set p2 that the processor 18 can determine may indicate whether the liquid jet 13 contacts the edge of the collision object 81. For example, by determining one or more locations where the liquid jet 13 contacts the collision object 81 (e.g., coordinates set by the CNC 31), and optionally further determining one or more locations where the liquid jet 13 does not contact the collision object 81, the processor 18 is able to determine the liquid jet position and / or liquid jet angle (relative to a predetermined axis), and may also be configured to perform correction or alignment of the liquid jet 13, such as alignment with a predetermined axis.

[0101] Figure 9 An example of signal fusion using rule-based algorithm 90 is shown. In the initial step 91 of algorithm 90, device 10 processes workpiece 11 with a laser beam guided by a liquid jet.

[0102] In step 92, algorithm 90 checks whether the signal 44s of photoelectric sensor 44 is greater than the first threshold (T1). If the signal 44s is greater than the first threshold, algorithm 90 continues to step 94; otherwise, there is a problem, and processing can be automatically stopped in step 93.

[0103] In step 94, algorithm 90 checks whether the signal 17s of vibration sensor 17 (or the signal 17c of vibration sensor 17 after frequency filtering by frequency filter 41) is greater than the second threshold (T2) and less than the third threshold (T3). If this is the case, algorithm 90 proceeds to step 95. If this is not the case, processing continues, and algorithm 90 returns to step 91.

[0104] In step 95, algorithm 90 checks whether signal 17s (or 17c) remains between the second threshold and the third threshold (T2, T3) for at least X seconds. X can be selected by the user. X can be measured using a timer. If it remains for at least X seconds, algorithm 90 proceeds to step 96. If it does not remain for at least X seconds, processing continues, and algorithm 90 returns to step 91.

[0105] In step 96, algorithm 90 checks whether the average value of the signal 43s from photoelectric sensor 43 is below a third threshold (T3) for at least Z seconds. Z can be selected by the user and can be equal to X. Z can be measured using a timer. If the signal has been maintained for at least Z seconds, algorithm 90 proceeds to step 97. If the signal has not been maintained for at least Z seconds, processing continues, and algorithm 90 returns to step 91.

[0106] In step 97, the processor 18 determines that the processing is complete and can proceed to the next step.

[0107] It is worth noting that steps 91-95 can also be executed simultaneously to analyze the processing and make decisions about it. As detailed above, this algorithm 90 can also be used, for example, to optimize processing efficiency or to control processing depth.

[0108] The invention has been described in conjunction with various embodiments and implementations as examples. However, other variations can be understood and implemented by those skilled in the art and those skilled in the art in practicing the claimed matters, through a study of the drawings, this disclosure, and the independent claims. In the claims and description, the word "comprising" does not exclude other elements or steps, and the indefinite article ("a" or "an") does not exclude plural forms. A single element or other unit can perform multiple functions of multiple entities or items recounted in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Claims

1. An apparatus (10) for processing a workpiece (11) with a laser beam (12) guided by a liquid jet (13), the apparatus (10) comprising: Nozzle (14), the nozzle being configured to generate the liquid jet (13); At least one lens (15) is configured to couple the laser beam (12) into the liquid jet (13); A housing (16) that at least surrounds the nozzle (15) and has an opening for providing the liquid jet (13) to the workpiece (11); Vibration sensor (17), the vibration sensor being attached to the housing (16); and Processor (18); The vibration sensor (17) is configured to measure at least a first vibration of the housing (16) and / or a second vibration of the housing (16); Wherein, the first vibration is caused by processing the workpiece (11) with the laser beam (12), and the second vibration is caused by the liquid jet (13); and The processor (18) is configured to determine a first set of parameters (p1) related to processing the workpiece (11) and / or a second set of parameters (p2) related to the liquid jet (13) based on measurements of the first vibration and / or the second vibration.

2. The apparatus (10) according to claim 1, wherein: The vibration sensor (17) is also configured to measure a third and / or fourth vibration of the housing (16); The third vibration is caused by photoacoustic resonance induced by the laser beam (12) within the housing (16), and the fourth vibration is caused by movement and / or rotation of the housing (16); and The processor (18) is configured to determine a third set of parameters associated with the device (10) based on measurements of the third vibration and / or the fourth vibration.

3. The apparatus (10) according to claim 1 or 2, wherein: The first vibration is based on a first sound (32), which is generated at the workpiece (11) by processing the workpiece (11) with the laser beam (12) and coupled to the housing (16) via the liquid jet (13) and the liquid (21) within the housing (16); and / or The second vibration is based on a second sound (33), which is generated by the liquid jet (12) and coupled to the housing (16) via the liquid jet (12) and the liquid (21) within the housing (16).

4. The apparatus (10) according to claim 3 further includes: A frequency filter (41) is arranged and configured to separate the first sound and / or the second sound traveling in the liquid jet (13) from other sounds.

5. The apparatus (10) according to any one of claims 1 to 4, wherein: The laser beam (12) is pulsed; and The vibration sensor (17) is configured to measure the occurrence of the first vibration within a time period shorter than the time delay between two consecutive laser pulses of the pulsed laser beam (12).

6. The apparatus (10) according to any one of claims 1 to 5, wherein: The laser beam (12) is pulsed; and The processor (18) is configured to determine the time difference between a first time when a specific laser pulse of the laser beam (12) is generated and a second time when the associated first vibration is measured by the vibration sensor (17).

7. The apparatus (10) according to claim 6, wherein, The processor (18) is configured to calculate, based on the time difference, the distance between the nozzle (14) and the incident point of the laser beam (12) on the workpiece (11), and / or the distance between the hole (19) and the incident point.

8. The apparatus (10) according to any one of claims 1 to 7, wherein, The vibration sensor (17) is attached to the outer surface of the housing (16) and in direct contact with the outer surface of the housing (16), or attached to an adapter (42) mounted on the outer surface of the housing (16).

9. The apparatus (10) according to any one of claims 1 to 8, wherein: The housing (16) includes a first part (16a) and a second part (16b), the first part (16a) being removably attached to the second part (16b). The second part (16b) of the housing (16) includes the at least one lens (15); The first portion (16a) of the housing (16) includes the nozzle (14) and a liquid chamber (21) located above the nozzle (14); and The vibration sensor (17) is arranged at the first part (16a) of the housing (16) on the liquid chamber (21) above the nozzle (14).

10. The apparatus (10) according to any one of claims 1 to 9, wherein, At least one parameter in the first parameter set (p1) indicates one or more of the following: The material type of the workpiece (11); Material removal rate or material removal percentage is achieved by processing the workpiece (11) with the laser beam (12); Has the laser beam (12) penetrated the workpiece (11)? 11. The apparatus (10) according to any one of claims 1 to 10, wherein, At least one parameter in the second parameter set (p2) indicates one or more of the following: The jet mass of the liquid jet (13) and / or the laminar length of the liquid jet (13); The flow characteristics of the liquid jet (13); Whether the laser beam (12) hits the nozzle (14); The liquid jet (13) either contacts the edge of a collision object (81) arranged near the workpiece (11) or contacts the workpiece (11) itself.

12. The apparatus (10) according to any one of claims 1 to 11, further comprising: Acoustic transducer (61), the acoustic transducer being arranged and configured to transmit acoustic waves (62) to the workpiece (11) via the liquid jet (13); The vibration sensor (17) is also configured to measure a third vibration caused by the sound wave (62) being reflected back from the workpiece (11) into the housing (16) by the liquid jet (13).

13. The apparatus (10) according to any one of claims 1 to 12, further comprising: One or more photoelectric sensors (43, 44), each of which is configured to detect a first radiation or a second radiation; The first radiation is caused by processing the workpiece (11) with the laser beam (12), and the second radiation is caused by guiding the laser beam (12) in the liquid jet (13) or by processing the workpiece (11) with the laser beam (12); The first radiation includes at least one of the following: laser light reflected from the workpiece (11) by the laser beam (12); and secondary radiation emitted by a portion of the workpiece (11) processed by the laser beam (12); and The processor (18) is configured to further determine the first parameter set and / or the second parameter set based on measurements of the first radiation and / or the second radiation.

14. The apparatus (10) according to claim 13, wherein, The processor (18) is also configured to: The vibration sensor (17) and the output signals (17s, 43s, 44s) of the one or more photoelectric sensors (43, 44) are fused together, wherein the output signals (17s, 43s, 44s) are generated based on the measured first vibration and / or second vibration and the measured first radiation and / or second radiation; and The first parameter set (p1) and / or the second parameter set (p2) are determined based on the fused output signals (17s, 43s, 44s).

15. The apparatus (10) according to claim 14, wherein: The processor (18) includes a trained model (51) or a rule-based algorithm and is configured to input the output signal into the trained model (51) or the rule-based algorithm; and The trained model (51) is configured to fuse the output signals (17s, 43s, 44s) and determine the first parameter set (p1) and / or the second parameter set (p2) based on the fused output signals (17s, 43s, 44s).

16. The apparatus (10) according to any one of claims 1 to 15, wherein, The processor (18) is also configured to adjust at least one operating parameter of the laser beam (12) and / or the liquid jet (13) based on the determined first parameter set (p1) and / or second parameter set (p2).

17. A method (70) for processing a workpiece (11) with a laser beam (12) guided by a liquid jet (13), the method (70) comprising: A liquid jet (71) is generated using a nozzle (14); The laser beam (12) is coupled (72) into the liquid jet (13) using at least one lens (15); At least (73) measure the first and / or second vibrations of the housing (16) surrounding the nozzle (14). Wherein, the first vibration is caused by processing the workpiece (11) with the laser beam (12), and the second vibration is caused by the liquid jet (13); and Based on measurements of the first vibration and / or the second vibration, determine (74) a first set of parameters (p1) related to processing the workpiece (11) and / or a second set of parameters (p2) related to the liquid jet (13).

18. The method (70) according to claim 17, wherein, The method (70) further includes modifying at least one operating parameter of the laser beam (12) and / or the liquid jet (13) based on the determined first parameter set (p1) and / or second parameter set (p2).

19. A computer program comprising instructions for controlling a device (10) according to any one of claims 1 to 16 when a processor (18) executes the instructions, or for causing the device (10) to perform the method (70) according to claim 17 or 18 when a computer executes the instructions.

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