Methods and machines for laser processing

Abstract

At a minimum, a) the step of directing a laser beam (5) onto a workpiece (2), b) the step of performing relative movement between the laser beam (5) and the workpiece (2), c) the step of monitoring the laser processing process, d) the step of determining at least one first quality parameter (y), and e) the step of determining that at least one first quality parameter (y) is a desired first quality parameter (y) 0 A laser processing method is described, which includes a step of verifying whether it corresponds to f) the first quality parameter (y) is a desired first quality parameter (y). 0 In response to the decision during step e) that it does not correspond to the second quality parameter (z), the process parameters are modified, and after the modification of the process parameters during step f) g) the second quality parameter (z) is the desired second quality parameter (z) 0 Step f) estimates whether the second quality parameter (z) corresponds to the desired second quality parameter (z) 0 In response to the estimation during step g) which does not correspond to the second quality parameter (z), and the second quality parameter (z) is the desired second quality parameter (z) 0 This includes the step of changing process parameters in order to obtain the corresponding result.

Description

[Technical Field]

[0001] Cross-reference of related applications This patent application claims priority to Italian Patent Application No. 102022000022032, filed on 25 October 2022, the entire disclosure of that document being incorporated herein by reference.

[0002] The present invention relates, in particular, to a laser cutting method for cutting and / or perforating and / or welding a workpiece, and / or for performing additive manufacturing to obtain a workpiece. More particularly, the present invention relates to a laser cutting method with continuous closed-loop control of the cutting or perforating of a workpiece, for laser cutting quality. Even more preferably, the present invention relates to a laser cutting method with closed-loop control having a main loop and an auxiliary loop.

[0003] The present invention also relates to a laser processing machine configured to perform a laser processing method. Preferably, the present invention relates to a laser processing machine configured to perform a laser processing method by closed-loop control of laser processing quality (preferably having a main loop and an auxiliary loop), and preferably by closed-loop control of processing to ensure a predetermined processing quality. [Background technology]

[0004] Laser processing machines are known, for example, for cutting and / or perforating workpieces. A typical laser processing machine includes a laser beam emitter, a support for the workpiece, an optical assembly for controlling the focal position of the laser beam, a generating device configured to generate a gas jet to direct compounds produced during processing of the workpiece away from the workpiece, and a moving device for performing relative movement between the laser beam and the workpiece.

[0005] During use, the qualitative results of cutting or drilling a workpiece depend, for example, on the intensity of the laser beam, the pressure of the gas jet, and / or the relative speed of movement between the laser beam and the workpiece.

[0006] For example, when cutting in a nitrogen atmosphere, burr formation is known to occur on the lower edge of the cut or perforated portion of the workpiece.

[0007] Theoretically, it might be possible to set process parameters in a predetermined, fixed manner to achieve the highest possible quality (i.e., the absence of burrs, for example). However, achieving such results requires setting process parameter values ​​in an extremely archaic manner, which would therefore lead to a reduction in productivity.

[0008] To optimize the trade-off between quality and productivity, it is necessary to obtain information on how to optimize process parameters to ensure quality while maximizing machining productivity, for example, through simulation, practical estimation, or direct measurement. It should be noted that optimizing process parameters results in the determination of a set of optimized process parameters, but these are static, i.e., they do not change during the machining of the workpiece. This means that in some environments, such an optimized set of process parameters may result in suboptimal machining in terms of both productivity and quality.

[0009] In Patent Document 1, the applicant proposed a method that enables the acquisition of desired quality while simultaneously achieving optimization of productivity.

[0010] The method proposed in the aforementioned patent application makes it possible to obtain very satisfactory results.

[0011] However, in this department, there is a felt need for further improvement in the laser processing method and / or laser processing machine, with the possibility of preferentially and continuously monitoring and adjusting the processing quality, and preferentially for cutting and / or perforating and / or welding the workpiece, and / or for performing additive manufacturing of the workpiece, and especially for facilitating the management of laser processing in different environments / atmospheres.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0013] An object of the present invention is to provide a laser processing method and a laser processing machine that make it possible to improve known methods so as to be able to easily manage laser processing in different environments / atmospheres, among other things.

[0014] Among other things, an object of the present invention is to provide a laser processing method and a laser processing machine that enable quality control and enable the control of the machine's process parameters as a function of the quality obtained.

Means for Solving the Problems

[0015] The above object is achieved by the present invention relating to a laser processing method defined in independent claim 1. Alternative preferred embodiments are protected in the respective dependent claims.

[0016] The above object is also achieved by the present invention relating to a laser processing machine according to claim 15.

[0017] To better understand the present invention, preferred embodiments thereof are described below, merely as non-limiting examples, and with reference to the accompanying drawings. [Brief explanation of the drawing]

[0018] [Figure 1] This figure schematically and partially illustrates the laser processing machine according to the present invention. [Figure 2a] This figure shows an example of an image acquired during laser processing using the operation of the processing machine shown in Figure 1. [Figure 2b] This figure shows the steps for analyzing the acquired image in Figure 2a. [Figure 3] This figure shows the temporal progression of characteristic parameters obtained from the analysis of multiple acquired images. [Figure 4] This figure shows the distribution of characteristic parameters obtained from the respective time progression of characteristic parameters during laser processing by the operation of the processing machine shown in Figure 1 under two different conditions. [Figure 5] This diagram schematically illustrates the control of a laser processing method. [Figure 6] This diagram schematically illustrates an example of laser processing control. [Modes for carrying out the invention]

[0019] In Figure 1, reference numeral 1 generally indicates a laser cutting machine configured to perform laser processing on a workpiece as a whole, and more preferably a laser cutting machine configured to cut and / or perforate workpiece 2.

[0020] Preferably, workpiece 2 can be made of a metallic material. In particular, workpiece 2 can have a planar shape and / or a tubular shape and / or a rod-shaped shape.

[0021] More specifically, laser processing machine 1 is, - A control unit 3 for controlling the operation of the laser processing machine 1; - A laser beam 5 emission source 4 is operably connected to a control unit 3 and configured to emit a laser beam 5; - The optical assembly 6 is operably connected to the control unit 3, primarily to control the laser beam 5, and primarily to direct the laser beam 5 along the optical axis A onto the workpiece 2 and into the work zone 7; - A moving device, preferably operably connected to the control unit 3, preferably configured to perform relative movement between the laser beam 5 and the workpiece 2 at a determined speed, and / or preferably configured to define the shape of the cutting and / or drilling. Includes.

[0022] Prioritizing, laser processing machine 1 also, - It may include a generating device (not shown, and known in itself) which is operably connected to the control unit 3 and, preferentially, configured to generate a gas jet for directing compounds generated during the cutting and / or drilling of the workpiece 2 away from the workpiece 2 during laser processing.

[0023] According to some preferred, non-limiting embodiments, the processing machine may also include a suction unit configured to remove fumes and / or by-products of the laser processing.

[0024] According to some preferred non-limiting embodiments, the control unit 3 can be configured to control process parameters of the laser processing machine 1, which are preferably the intensity and / or frequency of the laser beam 5, the duty cycle of the pulsed regime of the laser beam 5, and / or the focal position and / or the diameter of the laser beam 5, and / or the determined speed of relative movement between the laser beam 5 and the workpiece 2, and / or the gas jet and / or the gas pressure of the gas jet and / or the position of the nozzle configured to emit the gas jet.

[0025] Preferably, the control unit 3 can be configured to control process parameters in feedback mode.

[0026] It should be noted that process parameters are (substantially) all the parameters that define the operation of laser processing machine 1.

[0027] Advantageously, and particularly with reference to Figure 5, the control unit 3 may include at least one closed control loop 30, each of which preferably has a main loop 31 and an auxiliary loop 32.

[0028] Prioritizing the relationship between the main loop 31 and its auxiliary loop 32, each is engaged with the others and is hierarchical relative to them.

[0029] As described in more detail below, the main loop 31 can be configured to control control parameters under specific conditions, and the auxiliary loop 32 can be configured to control control parameters under other conditions, however, the other conditions are a direct result of the control performed by the main loop 31.

[0030] Preferably, the laser processing machine 1 also includes a monitoring device 8 configured to monitor the laser processing process and / or results. Preferably, the monitoring device 8 can be configured to monitor the cutting and / or drilling and / or welding and / or additive processes of the workpiece 2.

[0031] Preferably, the monitoring device 8 can be configured to acquire signals, preferably optical signals, and more preferably multiple acquired images 9 (exemplary acquired images are illustrated in Figure 2a) from the work zone 7.

[0032] In particular, the monitoring device 8 can be operably connected to the control unit 3, and the control unit 3 can be configured to control the operation of the laser processing machine 1, at least as a function of information extracted and / or acquired from the monitoring device 8, starting preferably from acquired signals, more preferably from acquired optical signals, and even more preferably from acquired images 9. Preferably, each closed control loop 30 can be configured to control the operation of the laser processing machine 1, at least as a function of information extracted and / or acquired from the monitoring device 8, starting preferably from acquired signals, more preferably from acquired optical signals, and even more preferably from acquired images 9.

[0033] Preferably, the monitoring device 8 can be configured to acquire signals, preferably optical signals, and more preferably acquired images 9 during the operation of the laser processing machine 1 (in other words, the monitoring device 8 can be configured to operate in online mode).

[0034] According to several preferred, non-limiting embodiments, the monitoring device 8 can be configured to capture process emissions, i.e., thermal emissions of heat (preferably present in the work zone 7). Alternatively, the monitoring device 8 can be configured to capture electromagnetic radiation (light) resulting from illumination by a separate light source.

[0035] Preferably, the emission source 4 can include a laser, such as an ND:YAG laser, a fiber-type laser, a carbon gas laser, or a diode laser.

[0036] More specifically, the optical assembly 6 can be configured to direct the laser beam 5 onto the workpiece 2 and to determine the focus of the laser beam 5.

[0037] Preferably, the optical assembly 6 can be configured to define an optical path P from the emission source 4 to the workpiece 2.

[0038] According to some non-limiting embodiments, the optical path P may include a first portion P1 transversely to the optical axis A, more specifically perpendicular to the optical axis A, and / or a second portion P2 coaxial with the optical axis A.

[0039] In other words, the laser beam 5 propagates along sections P1 and P2, respectively, with P1 perpendicular to P2, and preferably, direction P2 coincides with the optical axis A.

[0040] Alternatively, path P can be coaxial with optical axis A.

[0041] According to some preferred embodiments, the optical assembly 6 may include at least one focusing lens 14 configured to determine the focus of the laser beam 5, and preferably the focusing lens 14 may be located in portion P2.

[0042] Preferably, the optical assembly 6 may also include a collimation lens 15 and a dichroic mirror 16 configured to deflect the laser beam 5 from section P1 to section P2. In particular, the collimation lens 15 may be positioned in section P1.

[0043] Alternatively, the dichroic mirror 16 can be configured to deflect the optical axis A while leaving the path P of the laser beam 5 unchanged.

[0044] More specifically, the moving device can be configured to control the movement of the laser beam 5 relative to the workpiece 2 in a first relative forward direction D1, and / or in a second relative forward direction that is transverse (preferably perpendicular) to the first relative forward direction D1.

[0045] According to some preferred embodiments, the moving device may include a support (not shown, but known in itself) configured to support the workpiece 2, and preferably the support may be movable and be moved to obtain relative movement between the laser beam 5 and the workpiece 2.

[0046] Alternatively or additionally, at least one part of the moving device may be integrated into and / or associated with a support in order to move the workpiece 2 to obtain relative movement between the laser beam 5 and the workpiece 2.

[0047] Alternatively or additionally, the moving device may include a movable support base for carrying the emission source 4 and / or the optical assembly 6 and / or a portion of the optical assembly 6 in order to move the laser beam 5.

[0048] More specifically, the monitoring device 8 may include at least one sensor (preferably an optical sensor) configured to acquire a signal (preferably an optical signal).

[0049] The sensor may be, and / or include, a video camera 17 (for example, of the CCD or CMOS type) configured to acquire acquired signals, preferredly, acquired optical signals, and more preferably, acquired images 9.

[0050] More specifically, the video camera 17 can be configured to acquire the acquired images 9 sequentially, and to obtain a temporal sequence of the acquired images 9.

[0051] Preferably, the optical sensor, or more preferably, the video camera 17, can be configured to acquire the electromagnetic radiation beam 18 originating from the work zone 7.

[0052] According to several preferred, non-limiting embodiments, the electromagnetic radiation beam 18 can correspond to process emissions in the work zone 7. Alternatively, the electromagnetic radiation beam 18 can result from illumination of the work zone 7 (e.g., by a separate illumination source).

[0053] Preferably, the electromagnetic radiation beam 18 can pass through at least one part of the optical assembly 6 (in particular, the focusing lens 14 and the dichroic mirror 16).

[0054] According to some non-limiting embodiments, the optical sensor, preferably the video camera 17, can be positioned coaxially with the optical axis A. More preferably, the electromagnetic radiation beam 18 can propagate parallel to the portion P2 when in use.

[0055] Alternatively, the electromagnetic radiation beam 18 can propagate along a path having at least two portions that are transverse to each other.

[0056] More specifically, the monitoring device 8 may also include an optical filtering assembly 19, which is configured to ensure that the optical sensor, preferably the video camera 17, receives light in a defined band of wavelengths when in use. Preferably, the optical filtering assembly 19 may operate in the near-infrared region (it is a near-infrared filter).

[0057] In particular, the optical filtering assembly 19 can be positioned upstream of the video camera 17 with respect to the third direction.

[0058] As described in more detail below, the control unit 3 can be configured to control the operation of the laser processing machine 1, thereby obtaining the desired laser processing quality and ensuring continuous operation of the laser processing.

[0059] When in use, the laser processing machine 1 performs laser processing, and preferentially, the laser processing machine 1 cuts and / or punches the workpiece 2.

[0060] Advantageously, the laser processing method (preferably performed by laser processing machine 1) includes at least the following steps: a) The step of directing the laser beam 5 onto the workpiece 2, preferably within the work zone 7 of the workpiece 2, and / or to perform cutting and / or drilling of the workpiece 2; b) The step of performing relative movement between the laser beam 5 and the workpiece 2, preferably at a determined speed, and preferably to define the shape of the cut and / or drilling; c) A step of monitoring the laser processing process and / or the results of the laser processing in order to obtain information about the laser processing process and / or the results of the laser processing.

[0061] Furthermore, depending on the information obtained during step c), the method may include method control, preferably performed by a control unit, and preferably by at least one closed control loop 30.

[0062] To the advantage of this method, d) A step of determining, from the information obtained during step c), at least one first quality parameter y associated with at least one first effect of the laser processing; e) At least one first quality parameter y is a desired first quality parameter y 0 A step to verify whether it corresponds to; f) At least one first quality parameter y is a desired first quality parameter y 0 In response to the decision during step e) that it does not correspond to each of the desired first quality parameters y 0 The steps include modifying one or more process parameters to obtain at least one first quality parameter y corresponding to, Includes.

[0063] Prioritizing the execution of steps d) through f), each of the main loops 31 (see Figure 5) is performed.

[0064] Furthermore, the first quality parameter y is the desired first quality parameter y 0 In response to the decision made during step e) that corresponds to the first quality parameter y, the method repeats steps a) through e). More specifically, steps a) through e) are performed sequentially, and step f) is performed such that the first quality parameter y corresponds to each desired first quality parameter y 0 It is executed at the moment when it does not respond to the current situation.

[0065] However, the Applicant has observed that modifying one or more process parameters during step f) may result in a situation where at least one second quality parameter z associated with at least one second effect of the laser processing, which is different from the first effect of the laser processing, may no longer be satisfactory as a result of the modification of the process parameter. For this reason, the Applicant believes that it is necessary to determine whether the second quality parameter z continues to correspond to the desired second quality parameter z 0 (preferably in a predictive manner). If the second quality parameter z is no longer acceptable, preferably by the control unit 3, more preferably by each closed control loop 30, and even more preferably by each auxiliary loop 32, the method control needs to be guided by the need to ensure that the second quality parameter z remains within an acceptable range centered on the desired value z 0 .

[0066] According to some preferred non-limiting embodiments, the desired first quality parameter y 0 can change and / or be updated during the execution of the method. Alternatively or additionally, the desired second quality parameter z 0 can change and / or be updated during the execution of the method.

[0067] Advantageously, the method also includes g) after modifying one or more process parameters during step f), estimating (preferably in a predictive manner) whether at least one second quality parameter z associated with at least one second effect of the laser processing, which is different from the first effect of the laser processing, corresponds to at least one desired second quality parameter z 0 ; and h) At least one second quality parameter z is a desired second quality parameter z 0 In response to the estimation during step g) that does not correspond to, and at least one second quality parameter z corresponds to each desired second quality parameter z 0 To obtain the corresponding result, the steps involve changing one or more process parameters, Includes.

[0068] Furthermore, at least one second quality parameter z is a desired second quality parameter z 0 In response to the estimation during step g), which corresponds to the above, one or more process parameters are not modified.

[0069] More specifically, step h) is to set the second quality parameter z to each desired second quality parameter z 0 This is executed the moment it is determined that it does not support the specified condition.

[0070] By having a method that includes steps g) and h), it is possible to prevent laser processing from being performed by process parameters that lead to an unacceptable condition for the second quality parameter z.

[0071] Prioritizing the execution of steps g) and h), the respective auxiliary loops 32 are performed.

[0072] According to some embodiments, the auxiliary loop 32 operates according to a second quality parameter z, but not according to a first quality parameter y.

[0073] It should be noted that during step h), one or more process parameters can be changed directly and / or indirectly. For example, a direct change can be performed by an auxiliary loop 32 that directly interacts with the process parameter, and / or an indirect change can be performed by changing the desired first quality parameter y 0 This modification makes it possible to execute by auxiliary loop 32.

[0074] According to some preferred non-limiting embodiments, a value of a first quality parameter y, a value of a second quality parameter z, and a desired first quality parameter y 0 The value of and the desired second quality parameter z 0 The value of can change over time.

[0075] According to some embodiments, preferably, if one or more process parameters can be changed indirectly only, or directly and indirectly, during step h), step h) can be performed in cooperation between the control by each auxiliary loop 32 and the control by each main loop 31.

[0076] Preferably, step g) is performed in a predictive manner. Thus, step h) is performed quickly, and the second quality parameter z is no longer each desired second quality parameter z 0 It is guaranteed that it will be executed before it becomes incompatible.

[0077] Preferably, and especially referring to Figure 5, the main loop 31 is such that at least one second quality parameter z corresponds to each desired second quality parameter z 0 In response to the estimation during step g) corresponding to and the desired first quality parameter y 0 It is possible to control process parameters in order to obtain the first quality parameter y corresponding to this. In other words, the main loop 31 controls this method.

[0078] According to some embodiments, the main loop 31 can control process parameters according to a first quality parameter y, but it cannot control process parameters according to a second quality parameter z.

[0079] Furthermore, the auxiliary loop 32 ensures that at least one second quality parameter z corresponds to each desired second quality parameter z 0 In response to the estimation during step g) that does not correspond to, and at least one second quality parameter z corresponds to each desired second quality parameter z 0 To obtain a corresponding result, it is possible to control process parameters, for example, directly and / or indirectly. In other words, under these conditions, the auxiliary loop 32 controls the method. According to some embodiments, this control by the auxiliary loop 32 also controls a desired first quality parameter y 0 This can be achieved through modification and interaction with the main loop 31. According to such an embodiment, the auxiliary loop 32 interacts with the main loop 31 and thus controls the process parameters.

[0080] Such a control strategy should aim to prevent the deterioration of the second quality parameter z into an undesirable state, and consequently, it should be noted that controlling the second quality parameter z takes priority.

[0081] It should be noted that this method is performed in real time and / or for each workpiece 2.

[0082] According to some embodiments, steps c) through h) are performed between the execution of steps a) and b).

[0083] According to some non-limiting embodiments, steps a) and b) are preferably performed in the work zone 7 to cut and / or drill the workpiece 2. Furthermore, according to such embodiments, during step c), the cutting and / or drilling process, preferably the result of the cutting and / or drilling, is monitored.

[0084] Preferably, and as illustrated in Figure 5, during step h), changes to one or more process parameters are made according to at least the second quality parameter z.

[0085] In particular, during step h), in order to prevent the occurrence of an undesirable second quality parameter z, the desired first quality parameter y 0 However, it is modified and / or updated. In particular, during step h), the desired first quality parameter y 0 This is the previously desired first quality parameter y 0 It is modified to a value corresponding to a different quality compared to the original. In this way, it is possible to ensure that the second quality parameter z does not deteriorate. In other words, when it is estimated that the second quality parameter z deteriorates to an undesirable value, the requirements for the first quality parameter y and / or the first effect are modified, and in other words, this constraint on the first quality parameter y and / or the first effect is "relaxed" (i.e., the desired first quality parameter y is greater than in the ideal case). 0 (This is permissible), thereby allowing the process parameters to be shifted in a direction that prevents an undesirable second quality parameter z (which is a situation that should be prevented in particular).

[0086] According to such embodiments, in modifying one or more process parameters, the preferred first quality parameter y that results from the operation of each main loop 31 is preferred. 0It should be noted that by modifying this, it is possible to indirectly control one or more process parameters. Preferably, the auxiliary loop 32 controls the desired first quality parameter y 0 This modification controls the main loop 31.

[0087] It should be noted that one of the effects between the first and second effects corresponds to the respective results of the laser processing, such as roughness or burr formation as the first effect, or cutting loss or the rise of a deteriorated part on the lateral surface of the cutting slot as the second effect.

[0088] More specifically, in Figure 5, laser processing is indicated by G, E1 describes the first effect, C1 describes the control of the first quality parameter y, E2 describes the second effect, C2 shows the control of the second quality parameter z, and u represents one or more control parameters.

[0089] For example, a workpiece 2 made from a metal (e.g., carbon steel) can be cut and / or perforated. In such an example, the first effect can be said to be the presence of roughness in the cut and / or perforated portion, and a desired first quality parameter y 0This can correspond to a desired roughness (i.e., average roughness value), preferably a roughness within a determined range (i.e., average roughness value). If, during step e), it is determined that step f) is necessary, it is necessary to verify (preferably in a predictive manner) that the modification of the process parameter will not lead to cutting loss (defining the second effect). In particular cases, a second quality parameter is defined that is constrained by the second effect of cutting loss. In particular examples, it may be noted that the second effect is an effect that should be prevented, because if it occurs, it will require reworking of workpiece 2, resulting in production delays and material waste. Therefore, if, subsequently during step g), it is estimated that the modified process parameter may lead to cutting loss (i.e., the second quality parameter z is no longer acceptable), then step h) is performed to ensure that the second quality parameter z remains acceptable. Preferably, during step h), the desired first quality parameter y 0 This is modified, meaning that in certain cases, the desired roughness (i.e., the desired average roughness value) is modified to prevent the occurrence of cutting losses. In particular, when initial cutting losses are estimated, the performance requirement for roughness is reduced, and therefore this constraint is "relaxed" (i.e., a desired roughness (i.e., the desired average roughness value) greater than the ideal case is permitted), thereby allowing the process parameters to be shifted in a direction that prevents cutting losses (which is an event that should be prevented).

[0090] Another example concerns the case of laser cutting and / or drilling of an aluminum workpiece 2. The first effect may be burr formation, and the second effect may be the rise of degraded parts on the lateral surface of the cutting slot.

[0091] More specifically, the control unit 3 controls the laser processing machine 1, for example, by one or more closed control loops 30, to perform the laser processing method, and preferentially to process the workpiece 2.

[0092] Prioritizing this, the control unit 3 controls the laser processing machine 1 to perform at least steps a) through b).

[0093] According to some embodiments, steps a) and b) are performed sequentially on workpiece 2, preferably according to a defined scheme, and to obtain the desired result.

[0094] According to some embodiments, steps c) through h) are performed between the execution of steps a) and b).

[0095] Preferably, the method may also include one or more repeating steps i), during which steps c) through h) are repeated. More preferably, one or more steps i) are performed between the execution of steps a) and b).

[0096] In this way, continuous control of the laser processing is guaranteed.

[0097] According to a preferred embodiment, the first effect can be a continuous effect, and each first quality parameter y is continuously variable.

[0098] In particular, this means that a modification of one or more process parameters can result in a continuous modification of the result of the processing to the first effect, for example, when it occurs during step e). In other words, a modification of one or more process parameters can result in a continuous change in the quality parameter y, which may or may not be acceptable (i.e., it may result in a change to the desired quality parameter y). 0 (Whether it supports or does not support it). Preferredly, the desired quality parameter y 0 It is possible to define the acceptable range of quality parameters y.

[0099] An example of the first effect can be surface roughness or burr formation resulting from laser processing, preferably from cutting and / or drilling. These effects can be explained by their respective quality parameters y, each of which changes according to a continuous law with respect to modifications of one or more process parameters.

[0100] The second effect can be discrete, with each second quality parameter z varying discretely between acceptable and unacceptable quality.

[0101] More specifically, the second effect can be one which, when a modification of one or more process parameters occurs, for example during step f), does not result in a modification of the laser processing result to the second effect (it remains acceptable), or results in a modification of the processing result that becomes unacceptable. In other words, a modification of one or more process parameters either does not result in a modification of each second quality parameter z, or results in a modification of each second quality parameter z that becomes unacceptable.

[0102] Examples of discrete second effects include cutting loss, degradation of a portion of workpiece 2, or plasma formation. It is clear whether these effects are present or not, and furthermore, these effects should be prevented.

[0103] In other words, the second quality parameter z can be defined to vary between an acceptable value (e.g., defined as z=0) and an unacceptable value (e.g., defined as z=1). An increase in the second quality parameter z, in certain examples, signifies a deterioration of each quality, which is a situation that should be prevented.

[0104] Therefore, according to such preferred embodiments, the method provides quality control relating to continuous effects, and when modification of process parameters is necessary to ensure the desired quality for such continuous effects, this modification is controlled so as not to result in the occurrence of undesirable and discrete effects.

[0105] According to some embodiments, during steps d) and e), a plurality of first quality parameters y (i.e., a set of first quality parameters y) can be determined and verified, preferably associated with each first effect (different from other first effects), and preferably associated with a first sequence of effects. Preferably, during step f), one or more process parameters can be modified according to one or more quality parameters y, in particular, when the quality parameter y is each a desired quality parameter y 0 It may be modified to ensure compliance.

[0106] Additionally or alternatively, during step g), multiple second quality parameters z (i.e., a set of second quality parameters z) can be estimated and, preferentially, can be associated with each second effect (different from other second effects), and, preferentially, can be associated with each discrete second effect. Preferably, during step h), one or more process parameters can be modified according to one or more second quality parameters z, in particular, that the second quality parameter z corresponds to each desired second quality parameter z 0 It may be modified to ensure compliance.

[0107] According to some preferred embodiments, the method may further include step j) defining, during which at least one pair of each first effect and each second effect is defined.

[0108] For example, a pair can be defined by roughness as the first effect and by the loss of cutting as the second effect.

[0109] Another example is the pair defined by burr formation as the first effect, and by the degradation of a portion and / or slot of workpiece 2.

[0110] According to some non-limiting embodiments, one or more pairs can be defined by more than a first effect and / or more than a second effect.

[0111] According to some non-limiting embodiments, each pair can be associated with a closed control loop 30 having its own main loop 31 and its own auxiliary loop 32.

[0112] Prioritizing the first effect and the second effect (for example, of each pair), each may be a competing effect. This means that an improvement in each first quality parameter y as a result of modifying one or more process parameters may induce a deterioration in each second quality parameter z. For example, if the first effect is roughness and the second effect is loss of cutting, then during step e), it may be determined that the roughness (i.e., each first quality parameter y; i.e., each mean value) cannot correspond to the desired roughness (i.e., each first quality parameter y; i.e., each mean value), and during step f), one or more process parameters, such as the determined rate (which can, for example, be increased), may be updated. However, an increase in the determined rate may result in loss of cutting.

[0113] Furthermore, the fact that the first and second effects may be competing effects also means that an improvement in the second quality parameter z as a result of modifying one or more process parameters may induce a deterioration in the first quality parameter y. Returning to this example, it may be necessary to reduce the determined rate in order to prevent cutting losses, and this will lead to greater roughness.

[0114] Figure 6 schematically illustrates the control of laser processing according to the present invention, with reference to an example where the first effect is roughness (represented by y), the second effect is cutting loss (represented by z), and the process parameter that can be varied is the velocity (represented by u) (relative movement between the workpiece 2 and the laser beam 5).

[0115] In the example in Figure 6, it can be noted that initially, the speed is constant, there is a roughness that varies around the first average value, there is no cutting loss, and the speed is constant. However, according to the example, each first quality parameter y is a desired first quality parameter y 0 (i.e., the desired roughness) is not met, and consequently, the control unit 3, preferably each control loop 30, and more preferably each main loop 31, controls the increase in speed, which results in a reduction in the average roughness value, as schematically shown by their respective dashed lines. However, if the speed is maintained at the increased level, cut losses will also occur (see the parts of the respective dashed lines). Therefore, the control unit 3, preferably each control loop 30, and more preferably each auxiliary loop 32, must counteract the potential cut losses (preferably before such cut losses occur). Consequently, the speed is reduced to a value that leads to an average roughness value greater than initially desired, but this ensures that no cut losses occur. For example, the auxiliary loop 32 controls the updated desired first quality parameter y 0 It is possible to control this updated desired first quality parameter y 0 This is then considered by the main loop 31 to set a new speed in which no disconnection loss exists.

[0116] According to some preferred embodiments, steps c) through h) are carried out considering each pair, and preferentially considering the first effect of each and the second effect of each.

[0117] If multiple pairs are defined, steps c) through h) are performed relative to each pair, preferably simultaneously or alternatively.

[0118] According to some embodiments, one or more first effects and one or more second effects, and / or one or more pairs to be considered during steps e), f), g), and h), depend on the material of the workpiece 2.

[0119] More specifically, during step a), the emission source 4 is capable of emitting a laser beam 5, and the optical assembly 6 is capable of directing the laser beam 5 onto the workpiece 2. Preferably, the control unit 3 is capable of controlling the focus of the laser beam 5 by controlling the optical assembly 6 (preferably the focusing lens).

[0120] Preferably, during step b), the workpiece 2 and / or the laser beam 5 are moved. In particular, during step b), the support bearing the workpiece 2, and / or the support base bearing the emission source 4 and / or the optical assembly 6 are moved. More preferably, only the support bearing to move the workpiece 2 is moved.

[0121] Preferably, during step b), relative movement between the monitoring device 8 and the workpiece 2 may also be performed. More preferably, relative movement between the laser beam 5 and the monitoring device 8 is not performed. It should be noted that due to the relative movement between the laser beam 5 and the workpiece 2, the work zone 7 also changes in time relative to the workpiece 2.

[0122] According to some embodiments, the information obtained during step c) can be analyzed during step e) and / or during step g).

[0123] More specifically, during step c), the acquisition substep may be performed, during which the signals of the work zone 7, preferably the optical signals, more preferably the acquired images 9, are acquired, preferably by the monitoring device 8, and more preferably by the video camera 17.

[0124] Furthermore, during step d), a first quality parameter y is determined (or multiple first quality parameters y are determined) by the control unit 3, starting from the signal, preferably from the optical signal, and more preferably from the acquired image 9.

[0125] Alternatively or additionally, during step g), one or more second quality parameters z are estimated by the control unit 3, starting from the signal, preferably from the optical signal, more preferably from the acquired image 9.

[0126] Preferably, during step c), the signal, preferably the optical signal, and more preferably the acquired image 9, result from process emission (i.e., from heat).

[0127] Preferably, during step c), the temporal progression of the signal, preferably the optical signal, and more preferably the acquired image 9 is obtained.

[0128] More specifically, the analysis of the signal, preferably the analysis of the optical signal, and more preferably the analysis of the acquired image 9, is performed in a similar manner to determine or estimate the respective first quality parameter y and the respective second quality parameter z. In other words, steps d) and g) are similar, and / or the respective analyses are similar.

[0129] Priority is given to the control unit 3, which analyzes the signal, then the optical signal, and most importantly, the acquired image 9.

[0130] In the following, the analysis of signals, preferably the analysis of optical signals, and more preferably the analysis of acquired images 9, is described in general terms, with specific references to steps d) and g) where necessary.

[0131] More specifically, the analysis of signals, preferably the analysis of optical signals, and more preferably the analysis of acquired images 9, provides the following: - Determining the temporal progression (see Figure 3) of one or more characteristic parameters from the signal, preferably from the optical signal, and more preferably from the acquired image 9; - Calculating one or more statistical parameters from the temporal evolution of characteristic parameters; and, - Establish or estimate each quality parameter based on one or more statistical parameters.

[0132] In preference, the temporal progression of each characteristic parameter is determined over a defined time, and more preferably, over a defined fixed time.

[0133] Preferably, and with reference to Figures 2a to 2b in particular, the analysis of the signal, preferably the optical signal, more preferably the acquired image 9, provides a conversion to the transformed signal, preferably the transformed optical signal, and more preferably the transformed image 23. Then, each characteristic parameter is obtained from the transformed signal, preferably from the transformed optical signal, and more preferably from the transformed image 23.

[0134] It is possible to acquire high-intensity zones 24, preferably during signal conversion, preferably during optical signal conversion, and more preferably during the conversion of each acquired image 9.

[0135] Prioritizing this, the transformation can provide threshold analysis of the acquired image 9.

[0136] Preferably, the analysis of the signal, preferably the analysis of the optical signal, and more preferably the analysis of the acquired image 9 may include determining one or more characteristic parameters defined by or as a function of the high-intensity zone 24.

[0137] More specifically, one or more statistical parameters can be preferentially extracted by the control unit 3 from the respective probability distributions of the temporal course of each characteristic parameter (see Figure 4). For example, each statistical parameter is selected from a group consisting of its respective mean, its respective variance, and its respective asymmetry index of its respective probability distribution.

[0138] More specifically, quality parameters can be obtained from one or more statistical parameters, preferably by nonlinear or linear functions.

[0139] In particular, this method also allows for the selection of one or more desired first quality parameters y 0 and one or more desired second quality parameters z 0 It is possible to provide steps for defining this.

[0140] According to some non-limiting embodiments, the method also allows for the setting of one or more desired first quality parameters y 0 and / or one or more desired second quality values ​​z 0 While the correction can be made, it is possible to provide a correction step. For example, the correction step can be automatically actuated by the operator and / or by the control unit 3.

[0141] In preference, the laser processing machine 1 can be operated according to the method described.

[0142] By examining the characteristics of the laser processing machine 1 and the method according to the present invention, the advantages that can be obtained become clear.

[0143] In particular, it is possible to control the quality of laser processing.

[0144] A further advantage lies in the fact that laser processing can be controlled in different atmospheres (for example, in nitrogen and oxygen).

[0145] Another advantage is that it is possible to manage different materials that have different properties.

[0146] Furthermore, it is possible to achieve a reasonable compromise between the desired laser processing quality and productivity.

[0147] Additionally, it is guaranteed that continuous effects are optimized for each desired quality parameter, while discrete effects are prevented.

[0148] Finally, it is clear that modifications and alterations can be made to the laser processing machine 1 and the methods described and illustrated herein without departing from the scope of protection defined by the attached claims. [Explanation of Symbols]

[0149] 1. Laser processing machine 2 workpieces 3. Control Unit 4 Source of emission 5. Laser beam 6. Optical Assembly 7 Work Zones 8 Monitoring devices 9 images obtained 14 Focusing lens 15 Collimation Lens 16 Dichroic Mirrors 17 Video Cameras 18 Electromagnetic radiation beam 19 Optical Filtering Assembly 23 Converted Images 24 High-Intensity Zones 30 Closed control loop 31 Main Loop 32 Auxiliary Loops A optical axis D1 First relative forward direction P1 Part 1 P2 Second part

Claims

1. A laser processing method for a workpiece (2), preferably a laser processing method for a metal material, wherein the laser processing method comprises at least: a) Preferentially, the step of directing a laser beam (5) onto the workpiece (2) to perform cutting and / or drilling and / or welding and / or additive manufacturing, b) The step of performing relative movement between the laser beam (5) and the workpiece (2), c) A step of monitoring the laser processing process and / or the results of the laser processing in order to obtain information about the laser processing process and / or the results of the laser processing, d) A step of determining, from the information obtained during step c), at least one first quality parameter (y) associated with at least one first effect of the laser processing, e) The at least one first quality parameter (y) is such that each of the desired first quality parameters (y) ０ The steps include verifying whether it corresponds to ) and f) At least one first quality parameter (y) is one of the desired first quality parameters (y) ０ In response to the decision during step e) that does not correspond to the respective desired first quality parameter (y ０ The steps include modifying one or more process parameters to obtain the at least one first quality parameter (y) corresponding to the above, g) After step f) estimate, preferably in a predictive manner, a second quality parameter (z) associated with at least one second effect of the laser processing, which is different from the at least one first effect, and the second quality parameter (z) is determined to be at least one desired second quality parameter (z) ０ The step of comparing with ) h) The at least one second quality parameter (z) is the respective desired second quality parameter (z) ０ In order to obtain that it corresponds to, the steps include changing one or more process parameters in response to the estimation performed during step g), Laser processing methods, including those mentioned above.

2. During step h), the desired first quality parameter (y ０ ) is the previously desired first quality parameter (y ０ The method according to claim 1, wherein the value is modified to correspond to a different quality compared to ).

3. Steps d) through h) are controlled in a closed control loop (30) having a main loop (31) and an auxiliary loop (32). The main loop (31) controls the one or more process parameters in response to the estimation during step g) that the at least one second quality parameter (z) corresponds to the respective desired second quality parameter (z ０ ) and to obtain a first quality parameter (y) corresponding to the desired first quality parameter (y ０ ). The auxiliary loop (32) is such that the at least one second quality parameter (z) is such that each of the desired second quality parameters (z) ０ In response to the estimation during step g) that does not correspond to ), and the at least one second quality parameter (z) is the respective desired second quality parameter (z) ０ The method according to claim 1 or 2, wherein, in order to obtain that the process corresponds to the above, one or more process parameters are controlled, preferably directly or indirectly.

4. The auxiliary loop (32) is such that the at least one second quality parameter (z) is such that each of the desired second quality parameters (z) ０ In response to the estimation during step g) that does not correspond to ), and the at least one second quality parameter (z) is the respective desired second quality parameter (z) ０ The method according to claim 3, wherein one or more process parameters are controlled without considering the first quality parameter (y) in order to obtain that the result corresponds to the following:

5. The method further includes step i) which repeats steps c) to h), and / or The method according to any one of claims 1 to 4, wherein during step g), the information obtained during step c) is analyzed.

6. The method according to any one of claims 1 to 5, wherein the at least one first effect is a continuous effect, the at least one first quality parameter (y) is continuously variable, the at least one second effect is a discrete effect, and the at least one second quality parameter (z) varies discretely between acceptable and unacceptable quality.

7. The method according to claim 6, wherein, with respect to the at least one first effect, modification of one or more process parameters results in a continuous modification of the laser processing result, and with respect to the at least one second effect, modification of one or more process parameters results in an acceptable or unacceptable laser processing result.

8. The method according to any one of claims 1 to 7, wherein the first effect and the second effect are competing effects such that an improvement in the first quality parameter (y) as a result of modifying one or more process parameters may induce a deterioration of the second quality parameter (z), and an improvement in the second quality parameter (z) as a result of modifying one or more process parameters may induce a deterioration of the first quality parameter (y).

9. The method according to any one of claims 1 to 8, wherein the at least one first effect and the at least one second effect depend on the material of the workpiece (2).

10. The method according to any one of claims 1 to 9, wherein the at least one first effect is selected from the group consisting of surface roughness and burr formation resulting from the laser processing, and / or the at least one second effect is selected from the group consisting of cutting loss, deterioration of a portion of the workpiece (2), and plasma formation.

11. The method according to any one of claims 1 to 10, further comprising step j) defining at least one first pair of at least one respective first effect and at least one respective second effect.

12. During step j), at least one first pair of each first effect and each second effect, and a second pair of each first effect and each second effect are defined. The method according to claim 11, wherein the steps c) to h) are performed, preferentially simultaneously or alternatively, relative to each of the first pair and the second pair.

13. During step c), a substep is performed to acquire a signal, preferably an optical signal, from the work zone being processed by the laser beam. During step d), at least one first quality parameter (y) is determined from the signal, preferably the optical signal, and / or During step g), at least one second quality parameter (z) is determined from the signal, preferably the optical signal. The method according to any one of claims 1 to 12, wherein during the acquisition substep, a plurality of images of the work zone (2) are acquired as the signal.

14. The method according to any one of claims 1 to 13, wherein the method is performed in real time and / or with respect to each workpiece (2), and / or steps c) to h) are performed during the execution of steps a) and b).

15. A laser processing machine (1), wherein the laser processing machine (1) is - A control unit (3) for controlling the operation of the laser processing machine (1), - An emission source (4) is operably connected to the control unit (3) and configured to emit a laser beam (5), - An optical assembly (6) for controlling the laser beam (5), - A moving device operably connected to the control unit (3) and configured to perform relative movement between the laser beam (5) and the workpiece (2), Includes, A laser processing machine (1), wherein the control unit (3) is configured and / or programmed to control the emission source (4) and / or the optical assembly (6) and / or the moving device in a manner that performs the method according to any one of claims 1 to 14.

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