Method for laser machining planning and / or laser machining an object by means of a laser

Abstract

The invention relates to a method, in particular a computer-implemented method, for laser machining planning and / or laser machining an object (1), in which: a laser beam (2) of a laser can be guided along at least one specified movement path (3) on the object (1) by means of a Galvo-scan system (4); a location-dependent idealised focus profile zsoll(s) (7) is determined which specifies a focal position (18) of a laser focus (5) of the laser beam (2) in a laser propagation direction (6) along the movement path (3); the location-dependent idealised focus profile zsoll(s) (7) is extended by a tolerance range (11); and, from the location-dependent idealised focus profile zsoll(s) (7), a location-dependent adjusted focus profile (8) is determined such that at least dynamic limits of a focus actuator (16) for setting the focal position of the laser focus (5) are adhered to, and that the location-dependent adjusted focus profile (8) lies at least partly within the tolerance range (11). The invention furthermore relates to a computer program, a computer-readable storage medium and a laser machining device (19).

Description

[0001] Method for laser processing planning and / or for laser processing an object with a laser

[0002] The present invention relates to a method, in particular a computer-implemented method, for laser processing planning and / or for laser processing of an object, in which a laser beam of a laser can be guided along at least one predetermined movement path on the object by means of a galvo scanning system, in which a location-dependent idealized focus profile Zsoii(s) is determined, which specifies a focus position of a laser focus of the laser beam in a laser propagation direction along the movement path.

[0003] A method for laser processing is known from DE 10 2017 219 184 B4. In this method, the focus of a processing beam is adjusted using a focusing device.

[0004] In 3D scanning systems (i.e. scanning systems with a focusing device with a focus actuator (“z-axis”)), the achievable dynamics of the focus adjustment along the laser beam are usually significantly lower than the dynamics of the angular deflection of the laser beam and thus the positioning of the focus in the x- and y-direction, which is carried out by two galvanometer scanners.

[0005] It is known that in many processes the accuracy requirements for focusing are much lower than in the x- and y-direction, since position deviations in the focus along the beam (“z-direction”) on the order of the Rayleigh length have little effect in the laser process.

[0006] For the x-axis, y-axis, and focus actuators of the 3D scanning system's focusing device, controllers with tracking error are typically used. The axes follow the specified target path with a tracking error, which can also result in geometric deviations from the target path - especially if the path is not linear. Modern scanning systems use controllers without tracking error, although a controller with tracking error is often still used for the z-axis. For control-engineering reasons, tracking-free controllers require a temporal progression of the position specifications (trajectory) that can be implemented within the dynamic limits of the actuators (such as maximum speed and maximum acceleration). This is referred to as a "travelable trajectory or travelable movement path."

[0007] If lag-free controllers are used for all three axes of the scanning system, a viable trajectory must also be determined for the z-axis. If an acceleration- or jerk-limited 3D trajectory is calculated taking into account the dynamic limits of the z-axis, the overall speed is severely limited—particularly due to the low acceleration limit of the z-axis. This reduces processing throughput.

[0008] To achieve the highest possible throughput in the process, it is common practice for scanning systems with a z-axis subject to drag to control the 3D scanning system with a dynamic range where the focus actuator can no longer fully follow the movement in all situations. For example, this allows for local marking of hatchings that extend only slightly in the z-direction.

[0009] However, this approach has the disadvantage that it places a significant load on the z-axis motor, which is unnecessary. This can cause the motor to overheat, resulting in drift. Furthermore, a motor temperature limit may be exceeded, triggering an emergency shutdown of the system.

[0010] One object of the present invention is to reduce the load on a motor of a laser focusing device. A further object of the invention is to enable the use of a focusing device with a tracking-free controller while maintaining or improving the usable dynamics of the x- and y-positioning.

[0011] The problem is solved by a method, a computer program, a computer-readable storage medium and a laser processing device having the features of the independent patent claims.

[0012] A method, in particular a computer-implemented method, is proposed for laser processing planning and / or for laser processing of an object, in which a laser beam of a laser can be guided along at least one predetermined trajectory on the object using a galvo scanning system. Laser processing planning can be a process step that takes place before the laser processing of the object. Additionally or alternatively, laser processing planning can also take place parallel and / or simultaneously with laser processing. In this case, a future section of the processing path may already be planned during laser processing.

[0013] The method uses a location-dependent idealized focus curve z S0n(s) is determined, which specifies the focus position of a laser beam focus along the trajectory path in a laser propagation direction. The energy density, i.e., the energy per unit area or volume, is highest at the laser focus. In the laser propagation direction before and after the laser focus, the laser beam diverges, and the energy density is lower here compared to the laser focus.

[0014] Furthermore, the object itself and the movement path arranged on it are generally curved, so that the laser beam, as it is guided along the movement path, falls on the object at changing angles and the movement path has constantly changing distances to the galvo scanning system and / or to a focusing device of the laser. The laser focus must therefore be adapted to the movement path so that the object is always processed along the movement path by the laser focus. The laser focus or its focus position should ideally always be set so that it is in the movement path. On the other hand, if the laser focus is positioned above the object and thus above the movement path, the laser beam diverges again before it hits the movement path on the object. This means that a wider area around the movement path is processed, which can be disadvantageous.Furthermore, due to the diverging laser beam, the energy density, i.e. the energy per area or volume, may no longer be sufficient to process the object. The same occurs if the laser focus or the fictitious laser focus is positioned behind the object or behind the movement path. As a result, the laser beam is not yet focused and a wide area around the movement path is processed and / or the energy input per area or volume or the energy density is not sufficient to process the object along the movement path. In the process, the location-dependent idealized focus path is, for example, S0 n(s) of the focus position of the laser beam in the laser processing device along the trajectory path is determined. The location-dependent idealized focus path z S0n(s) specifies the focus position of the laser focus along the trajectory, so that it is always in the trajectory. The location-dependent idealized focus path Zsoii(s) depends on a trajectory parameter s. The trajectory parameter s can, for example, specify a path length or arc length or a distance or a path along the trajectory. The trajectory parameter s can, for example, be normalized so that s is between 0 and 1. This means that s = 0 is the start of the trajectory and that s = 1 is the end of the trajectory. The trajectory parameter s can also be specified in millimeters or centimeters. The trajectory is therefore a function of the trajectory parameter s. In a sense, the trajectory parameter s parameterizes the trajectory.

[0015] Furthermore, the method uses the location-dependent idealized focus curve z S0n(s) is extended by a tolerance range. The tolerance is a distance that separates the real focus position of the laser focus from the ideal focus position according to the location-dependent idealized focus curve z S0 n(s) along the laser propagation direction.

[0016] In addition, the method uses the location-dependent idealized focus path Zsoii(s) to determine a location-dependent adjusted focus path such that at least the dynamic limits of a focus actuator for adjusting the focus position of the laser focus are maintained and that the location-dependent adjusted focus path lies at least partially within the tolerance range. The focus actuator adjusts the focus position of the laser focus according to the location-dependent adjusted focus path. With the help of the focus actuator, the focus position of the laser focus can be moved along the laser propagation direction. The focus position is moved along the laser propagation direction such that the location-dependent adjusted focus path is achieved along the trajectory path.By determining the location-dependent, adjusted focus path in relation to the dynamic limits of the focus actuator, the laser processing is planned from the outset in such a way that the focus actuator can map the location-dependent, adjusted focus path and / or is subjected to minimal stress. Only after such laser processing planning does the laser processing take place along the previously planned trajectory or the previously determined location-dependent, adjusted focus path. This prevents overloading of the focus actuator from the outset and ensures that the focus actuator can map the location-dependent, adjusted focus path so that the object is processed as intended or within the tolerance range for the focus position of the laser focus. With the help of the focus actuator, the focus position of the laser focus can be adjusted and / or moved in the laser processing direction.

[0017] Some terms are explained here. For example, one can speak of a longitudinal movement of the focus position of the laser focus along the laser propagation direction. This longitudinal movement means that the focus position of the laser focus is moved along the laser beam or the laser propagation direction. This longitudinal movement is generated by the focus actuator. For example, the focus actuator can be coupled to a focusing device. For example, the focus actuator can move a focusing unit, such as a focusing lens, so that the focus position is moved along the laser propagation direction or the longitudinal movement of the focus position is achieved. In contrast, a movement of the laser focus along the movement path can be referred to as a path movement because the laser focus is moved along the movement path.

[0018] Thus, when the location-dependent, adjusted focus path changes along the trajectory, a longitudinal movement of the laser focus position along the laser beam or along the laser propagation direction should occur. The focus actuator is controlled using the location-dependent, adjusted focus path or with control data based on the location-dependent, adjusted focus path. This control can be performed by a processing unit and / or control unit.

[0019] It is advantageous if the location-dependent idealized focus curve is used to determine the location-dependent adjusted focus curve. S0n(s) is smoothed. This smoothing can also be performed section by section, so that the location-dependent idealized focus curve Zsoii(s) is smoothed section by section. This removes kinks present in the location-dependent idealized focus curve Zsoii(s), particularly in the sections where smoothing is performed. This avoids, for example, abrupt changes in the direction of the focus actuator, which occur when the longitudinal movement of the focus position is suddenly changed along the laser processing direction.

[0020] It is advantageous if the location-dependent idealized focus path Zsoii(s) is determined in such a way that any section-wise curvature of the location-dependent adjusted focus path is minimal. This allows the focus actuator to apply only small accelerations.

[0021] Furthermore, it is advantageous if a location-dependent speed profile of the laser focus along the movement path is determined based on the location-dependent, adjusted focus profile. The location-dependent speed profile is determined, for example, in such a way that the focus actuator can execute the location-dependent, adjusted focus profile. If, for example, the location-dependent focus profile exhibits changes that are too large in magnitude, the focus actuator may not be able to execute these changes. In areas where changes are too large, the location-dependent speed profile can be determined in such a way that the focus actuator has sufficient time to execute the changes in the location-dependent, adjusted focus profile.

[0022] Additionally or alternatively, the location-dependent speed profile can be determined in such a way that a planned energy input along the movement path is achieved. If, for example, the focus position of the laser focus is not exactly in the movement path, the movement path is processed with an expanded laser beam, since the laser focus is either in front of or behind the movement path. However, the energy input of the laser per area then decreases, so that in an unfavorable case, for example, metal along the movement path is no longer completely melted for welding. A location-dependent speed profile can be determined which is comparatively low in these areas, so that the laser remains in a section of the movement path for a longer time and, as a result, for example, sufficient metal is melted again for welding.According to an advantageous development of the invention, it is useful if the location-dependent adjusted focus profile and / or the location-dependent speed profile is planned such that at least one acceleration and / or one jerk of the focus actuator is limited and / or lies within the dynamic limits of the focus actuator. The limitation of the acceleration and / or jerk of the focus actuator depends on the focus actuator itself. The focus actuator has limits for the acceleration and / or jerk that it can execute. If these limits and / or the dynamic limits of the focus actuator are taken into account when determining the location-dependent adjusted focus profile and / or the location-dependent speed profile, these limits are always adhered to.

[0023] It is advantageous if the location-dependent adjusted focus curve and / or the location-dependent speed curve are determined in such a way that the thermal limits of a focus actuator for adjusting the focus position of the laser focus are adhered to. The focus actuator may overheat if it has to adjust the laser focus too quickly and / or too frequently, or if the accelerations occurring are too high on average over time. This can be taken into account when determining the location-dependent adjusted focus curve and / or the location-dependent speed curve. In the event of overheating, for example, the location-dependent speed curve can be determined to be lower, giving the focus actuator more time to move the laser focus.

[0024] Furthermore, it is advantageous if, in the event of a violation of the tolerance range, particularly a violation calculated in advance, due to the location-dependent adjusted focus curve, the location-dependent speed curve is reduced in at least these areas. This provides the focus actuator with more time to adjust the location-dependent adjusted focus curve.

[0025] According to an advantageous development of the invention, it is useful to determine a location-dependent laser power profile along the trajectory, based on the location-dependent speed profile and / or the location-dependent adjusted focus profile, so that a planned energy input profile along the trajectory is achieved. This ensures that the intended amount of energy is introduced into the object for each section of the trajectory. If the energy level is too low, for example, during welding, the metal will not be completely melted. If the energy level is too high, too much metal may be melted, which can also be disadvantageous.

[0026] It is advantageous if a location-dependent temperature profile of the focus actuator is determined based on the location-dependent adjusted focus profile and / or the location-dependent speed profile, especially simulated before laser processing.

[0027] It is beneficial if the movement path is planned in such a way that it has at least one processing section and at least one jump section, wherein the object is processed with the laser in the processing section and the laser is switched off in the jump section. The at least one jump section borders on the at least one processing section, is attached to the processing section at an insertion point and / or connects at least two processing sections to one another. A jump section can be inserted if, for example, two processing sections are spaced from one another. Furthermore, a jump section can be inserted if it is not possible for the focus actuator to form the location-dependent, adapted focus path. For example, a loop can be inserted into the movement path of the laser beam at one point, namely the insertion point.This loop allows the focus actuator time to adjust the focus position according to the location-dependent, adjusted focus path—particularly to establish the required speed of the focus change for the processing section through a preparatory acceleration process. At the insertion point, the laser beam is decoupled from the processing path and recoupled after the loop, with the focus position and / or speed of the focus variation being adjusted during this loop. Such insertion points can be advantageous, for example, if the movement path and / or a height profile of the object exhibits a bend, requiring the focus position to be changed relatively quickly.It is advantageous if the movement path is divided into at least two processing sections in such a way that a constant speed profile of the laser focus can be determined along the respective processing sections. This allows for consistent processing of the object.

[0028] According to an advantageous development of the invention, it is useful if the movement path is divided into at least two processing sections in such a way that in the at least two respective processing sections the speed profiles of the laser focus along the corresponding processing sections are different from one another and that the speed profile in the jump section is planned in such a way that the speed profiles of the processing sections are connected to one another.

[0029] It is advantageous if the tolerance range, particularly in at least one processing section, is set to a value between 1% and 200%, in particular 20% to 100%, of a Rayleigh length of the laser. The Rayleigh length is the distance from the laser focus at which a cross-sectional area corresponds to twice the cross-sectional area at the laser focus. The smaller the tolerance range, the more precisely the laser focus is positioned relative to the movement path. As a result, the object can be processed more precisely. However, a larger tolerance range may also be sufficient. A larger tolerance range has the advantage that it is easier to adhere to. The larger tolerance range also makes it possible to protect the focus actuator and / or plan the speed profile at higher speeds.

[0030] It is expedient if the tolerance range, particularly in at least one processing section and / or in at least one jump section, is set constant at least in sections. For some areas, a larger tolerance range may be sufficient, whereas other areas require a smaller tolerance range. Additionally or alternatively, it may be useful to specify the tolerance range based on location. For example, it can vary depending on the angle of incidence of the laser over the workpiece, be determined by the local focusing properties of the scanning lens depending on the x-y position, or depend on the material to be processed at the respective location.

[0031] Depending on the requirements of the laser process, the tolerance range can advantageously be symmetrical around the ideal focus position, but it can also be given by different distances above or below the idealized focus position.

[0032] It may be advantageous to specify the tolerance range along the trajectory path as variable and / or location-dependent. The tolerance range can be determined from a laser process property, such as a process threshold for the laser intensity, and can also be calculated based on the location along the trajectory path using a physical process relationship. For example, it may be advantageous to consider the location-dependent focusing properties of an f-theta optic or an oblique incidence of the laser beam on the workpiece.

[0033] According to an advantageous development of the invention, it is useful if the tolerance range is enlarged and / or ignored in the jump section. Since the laser can be switched off here, the laser's focus position does not need to be taken into account.

[0034] An advantage results if, in at least one jump section, the focus path arranged therein is planned in such a way that a transition, in particular a continuous and / or movable one, is created to the adapted focus path of the adjacent processing section. "Movable" here means that the specified focus path can be controlled by the focus actuator without violating its dynamic limits, such as maximum jerk, maximum acceleration, or maximum speed.

[0035] Furthermore, it is advantageous if the method for laser processing planning, in particular the determination of the location-dependent idealized focus profile z S0n(s), the location-dependent adjusted focus curve, the location-dependent speed curve, the location-dependent power curve, and / or the location-dependent temperature curve, is carried out before laser processing of the object and / or for future sections of the trajectory during laser processing of the object. This allows for optimal laser processing planning, since the laser processing planning or the curves mentioned here can be planned first and adjusted if necessary.

[0036] An advantage arises if the laser processing planning is at least partially repeated if the tolerance range, the dynamic and / or thermal limits of the focus actuator are violated. In this case, the location-dependent adjusted focus curve, the location-dependent speed curve, the location-dependent power curve can be adjusted and / or at least partially modified. If a violation of the tolerance range, the dynamic and / or thermal limits of the focus actuator still occurs, the location-dependent adjusted focus curve, the location-dependent speed curve, the location-dependent power curve can be adjusted again and / or at least partially modified. The adjustment of the aforementioned curves can be repeated until the tolerance range or the specified limits are met.

[0037] An improvement results if a smoothing filter, in particular an FIR filter, preferably a moving average or a binomial filter, is used for smoothing.

[0038] It is advantageous if the method for laser processing planning and / or for laser processing of the object is carried out by a computing unit. The computing unit can also be a control unit of a laser processing device. Additionally or alternatively, the computing unit can also comprise the control unit. Additionally or alternatively, the control unit can also comprise the computing unit.

[0039] Also proposed is a computer program which, when executed by a computing unit, causes the computing unit to execute the method according to one or more features of the preceding and / or subsequent description. Also proposed is a computer-readable storage medium comprising a computer program, wherein the computer program, when executed by a computing unit, causes the computing unit to execute the method according to one or more features of the preceding and / or subsequent description.

[0040] Furthermore, a laser processing device for laser processing planning and / or for laser processing of an object is proposed.

[0041] The laser processing device comprises a laser for laser processing the object. The laser can be used, for example, to weld, cut, and / or mark the object. The laser processing device can comprise a laser source for generating the laser. Additionally or alternatively, the laser can also be coupled into the laser processing device from an external laser source.

[0042] The laser processing device further comprises a galvo scanning system for guiding a laser beam of a laser over the object, wherein the galvo scanning system comprises a focus actuator for adjusting a focus position of a laser focus of the laser beam. The galvo scanning system can, for example, comprise a focusing device that includes the focus actuator. For example, the focus actuator can move a focusing unit of the focusing device so that the focus position is moved along the laser propagation direction.

[0043] Furthermore, the laser processing device has a computing unit. The computing unit can also be a control unit of a laser processing device. Additionally or alternatively, the computing unit of the laser processing device can also comprise the control unit of the laser processing device. Additionally or alternatively, the control unit of the laser processing device can also comprise the computing unit of the laser processing device.

[0044] The computing unit is configured to perform the method according to one or more of the method steps described in the preceding and / or following description. The laser processing planning and / or the laser processing can also proceed, for example, as follows.

[0045] 1.) The processing task is divided into processing sections (“Mark”) and jump sections (“Jump”).

[0046] 2.) The planning of the path [x(s(t)), y(s(t))] is carried out according to conventional procedures for

[0047] 2D, so that the dynamic limits of the x / y galvos are maintained. The temporal progression of the path progression s(t) is thus initially fixed. Typically, the marking speed is planned with a generally constant marking speed in processing sections, and jumps within jump sections are planned for optimal time.

[0048] 3.) The calculation of z_soll(s) in the processing sections is carried out using a functional dependency z_soll(s) = z(x(s), y(s)) - in particular for producing a flat field correction.

[0049] 4.) In order to achieve the geometric progression of the z-coordinate z_soll(s) specified in this way,

[0050] A tolerance band [z_min(s) ... z_max(s)] is defined for each processing section, the width of which depends on a locally acceptable defocus. In the jump sections, the tolerance band is defined as the maximum value range within which the focus actuator can be controlled.

[0051] 5.) A smoothed curve z(s) is defined which runs completely within the tolerance band and has an essentially minimal curvature d 2 / ds 2 (z) along the trajectory. This step is independent of step 2 in terms of sequence, since steps 3, 4, and 5 can occur independently of the temporal progression of z.

[0052] 6.) It is checked whether z(s(t)) exceeds the dynamic limits (especially speed and

[0053] Acceleration) of the z-actuator. If not, the speed is reduced / limited, and the planning process is repeated from step 2. It may be advantageous to specify different speed limits for the marking speed and the jump speed, or to set a speed limit only locally. This can be determined from an analysis of the limit violations of z(s(t)). 7.) Optionally, it can also be checked whether the thermal limit of the z-drive is not exceeded by the control program, and the speed can be further reduced.

[0054] 8.) Optionally, the deviation of the z-coordinate from the ideal path öz = | z(s(-) - z_Soll(s(t)) | can be compensated by controlling the laser, whereby further compensations such as speed deviations can be taken into account.

[0055] A more general planning approach may also include the following steps and features:

[0056] 1. Compensation of defocusing by controlling another degree of freedom—in particular, the laser power—based on a characteristic curve that describes the relationship between the achieved effect of the laser radiation and the defocusing for the laser process. This can also include: a. the influence of the path speed, b. the influence of an oblique incidence due to the x / y deflection.

[0057] 2. Planning the trajectory using an optimization procedure with the following characteristics:

[0058] For the planning of the sections with active laser (processing section), a tolerance band [z_min(s) ... z_max(s)] around the course of the z-coordinate z_soll(s) of the target path is defined for each point p_soll(s) = (x_soll(s), y_soll(s), z_soll(s)) along the 3D target path depending on a property of the laser beam (in particular depending on the Rayleigh length) and the laser process (in particular a tolerance against defocusing of the laser).

[0059] The trajectory p(s) is planned in the processing sections with the following boundary conditions and optimization goals a - e: a. Small geometric deviation |x_soll(s) - x(s)| or |y_soll(s) - y(s)| and from the target path in the x and y directions. b. Z coordinate within the tolerance band z_min(s) <= z(s) <= z_max(s), whereby the deviation from the center |z(-) - z_soll(s)| can optionally be kept small. c. Low heating of the z-axis drive (modeling with integral of the current and cooling, minimization of the acceleration used, if necessary depending on a modeled temperature). d. Small deviation of the velocity v(s) = d / dt(p(s(t)) from a desired path velocity v_soll or section-wise maximization of the section-wise constant path velocity. e. No violation of the dynamic limits of the x-, y- and z-axes (dynamic limits are typically maximum values ​​of the first, second and third time derivatives of components of p(s(t)).

[0060] The optimization can be performed with an optimization goal in mind, which includes a specific weighting of the criteria a - e mentioned above. The weighting of the criteria can also be influenced by a user specification, e.g., by parameters of a marking command in a machine-readable description of the processing task.

[0061] It may be that the optimization cannot be carried out in a meaningful way for the entire length of the path, but that it makes more sense to split the path into at least two sections, which are then connected by an inserted phase with a deactivated laser.

[0062] The optimization algorithm can perform such divisions automatically based on suitable criteria.

[0063] In the phases with a deactivated laser (“jump” section or jump sections of the machining task), the path along which the laser focus is guided is irrelevant. Here, optimization is carried out for a short execution time while adhering to the boundary conditions at the start and end of the section, which are specified by the ends of the adjacent mark phases or machining sections (phases with an active laser). The dynamic limits of the drives of the x, y, and z axes are taken into account. The tolerance band for the z movement can also be used as a free space for optimization at the transition points between jump and mark sections or jump and machining sections. In particular, the optimization algorithm can perform holistic optimization across several connected jump and mark sections or jump and machining sections by planning at least one mark section with a z deviation other than 0 at the start or end.

[0064] The process can also be performed interactively with a user. Software can display a planning result and indicate critical points where boundary violations are occurring. The user can then be prompted to select an algorithm from a list to be used to correct boundary violations. For example, the user can change parameters to make the set boundaries less strict, or alternatively, have the software insert a jump phase or jump sections to correct the boundary violation.

[0065] In order to comply with the specifications of the laser process with the least effort from the user, if the application is a so-called 2.5D laser process in which the z-component has a subordinate importance, e.g. that it only results from the flat field correction or the correction of the surface curvature of the workpiece to be machined.

[0066] A possible alternative planning approach can also be described by the following steps:

[0067] Step 1: Starting from the specified target trajectory p(s)=(x(s), y(s), z(s)) (this is also the location-dependent idealized focus path), a trajectory p_xy(s(t)) = (x(s(t)), y(s(t)) is initially planned for the x and y components of the movement only by defining the temporal progression of the trajectory parameter s(t). In this step, the dynamic limits for the galvos of the scanning system are taken into account. The trajectory speed | d / dt(p(s(t))| is kept essentially constant along the trajectory at the value of a specified target trajectory speed. Corners are rounded off up to a geometrically specified maximum corner deviation in order to comply with the dynamic limits of the galvanometer drives. If the rounding of corners is not sufficient, the trajectory is automatically divided into two sections and connected by a backswing movement with the laser switched off (“skywriting”).

[0068] Step 2: Based on the result of this planning, the temporal target course of the z-coordinate z_soll(s(t)) is determined based on the determined path progress s(t).

[0069] Step 3: By digital filtering of z_Soll(s(t)) a smoothed temporal course of z(s(t)) is determined, whose acceleration \d 2 / dt 2 (z(s(t)))\ does not exceed a specified maximum acceleration a_z_max of the focus actuator. The filter parameters can either be predetermined to ensure that the acceleration limit is reliably maintained, or the filter parameters can be adjusted iteratively until the condition is met.

[0070] Step 4: For the resulting curve z(s(t)) (this is the location-dependent adjusted focus curve), it is determined whether it lies everywhere within the tolerance limit z_min(s) <= z(s) <= z_max(s). If this is the case, the planning result has been achieved. If this is not the case, the specified target speed is reduced (at least in the relevant section of the path), and the entire process is repeated with the new, lower target speed.

[0071] If the machining task is divided into several sections with different speeds for this reason, it is advantageous to connect these sections with inserted phases with the laser switched off to adjust the changed target speed. Alternatively, a transition with a time-varying path speed can be inserted to fade from one path speed to the other.

[0072] As a modification or alternative to the method described above, the following is also possible and can be particularly advantageous for enabling an efficiently implemented algorithm. This is particularly suitable for cases in which the z-movement is a focus correction resulting from the x and y values. Step 1 a: Path planning for the x and y components is carried out using a conventional method. This determines a travelable time profile x(s(t)) and y(s(t)) for the x and y actuators. In particular, an essentially constant path velocity can be planned.

[0073] Step 1 b: The purely geometric progression of z(s) is calculated so that the tolerance band z_min(s) <= z(s) <= z_max(s) is maximally utilized to achieve the smoothest possible progression of the geometric path specification. The maximum values ​​of the derivatives dz / ds, d 2 z / ds 3, ...are minimized. Thus, a geometric path z(s) with the maximum rounding with respect to the z-component is first determined. (This step can be performed essentially independently of step 1a, provided the specified geometry of the path is not changed in step 1a.)

[0074] Step 2: Using the time profile of the path parameter s(t) determined in the xy path planning, it can then be checked whether the dynamic limits of the z-actuator along the (geometrically rounded) path z(s(t)) are also being maintained at the specified path velocity. If this is not the case, the velocity is reduced, analogous to the procedure described above, and the planning process is repeated with the new velocity value. Here, too, the machining task can be divided into sections, as in the above procedure.

[0075] This method can be numerically more advantageous because the rounded path does not need to be recalculated when the path speed changes. A method for finding the optimal marking speed is therefore numerically more efficient in this variant. The method can also be advantageous because, at a given marking speed, the z-axis actuator is subjected to minimal load and thus operates (almost) optimally from a thermal perspective. A disadvantage of this method is that the deviation of the z-coordinate can become unnecessarily large, as the tolerance band is always heavily exploited. In practice, this disadvantage is remediable, as the tolerance band can also be specified more narrowly by the user. The trajectory planning can be performed, for example, using the following method, in which the time course of the path progress is determined in advance based on a planning for x(t) and y(t). This method has the following steps:

[0076] 1 . Planning is performed first for the x- and y-components based on the dynamic limits of the corresponding actuators. This provisionally defines the path progression s(t): x(s(t)), y(s(t)). In this step, a substantially constant marking speed can be specified while maintaining the dynamic limits of the x- and y-axes.

[0077] 2. The tolerance band is then defined around the z-coordinates, whereby the limits of the tolerance band z_min(s(t)) and z_max(s(t)) are defined for each time t by the time parameterization already determined.

[0078] 3. The z-trajectory is planned using an optimization algorithm that determines the progression of the z-coordinates along the time axis within the tolerance band. The limitation of the z-dynamics can be described, for example, by maximum values ​​for velocity and acceleration in the z-direction: |dz / dt| < v_zmax and |d 2 z / dt2 | < a_zmax.

[0079] A very simple, but numerically not particularly efficient, method is iterative filter parameter optimization. The target curve of the z-coordinate is filtered in such a way that the dynamic limits are reliably met. A search procedure can be used to determine the filter parameters that further restrict the dynamics of the z-axis without violating the tolerance band.

[0080] One goal may be to keep the model-based calculated actuator heating below a certain temperature threshold. The filter parameters can also be selected differently for each section. Smoothing filters, such as FIR filters, can be used, particularly a moving average or a binomial filter.

[0081] 4. If such a z-trajectory cannot be determined for the entire trajectory, the trajectory is divided into sections connected by transition trajectories (jump sections, so-called "skywriting"). Alternatively, the specified dynamic limit of the x- and y-axes is reduced for at least part of the trajectory or the entire trajectory, and the procedure is applied again for these sections. This can, for example, correspond to a reduction in the constant marking speed selected for the x- and y-movement.

[0082] The optimization task with compliance with a tolerance band is similar to the so-called “racing car” optimization task, for which there are many publications with suitable methods.

[0083] Path optimization with minimization of drive heating is similar to the task of path planning for robots, with the goal of optimizing energy consumption.

[0084] When planning the motion, as outlined above, one optimization goal can be to limit the heating of the drives. The heat is introduced via electrical energy and is primarily caused by ohmic losses in the drive coils. Other mechanisms include friction losses due to internal and external friction effects, as well as inductive heating due to eddy currents and Ilm magnetization. Through these mechanisms, the energy supplied to the system components is partially deposited as heat in the actuator.

[0085] The system behavior can be approximately described by models. For example, the energy input via ohmic heating can be calculated by a time integral over the supplied current. The acceleration of an electromagnetic drive is approximately proportional to the current strength.

[0086] The heating is counteracted by cooling mechanisms, which can be modeled by a thermal resistance and a temperature difference to a reservoir. It is also possible to use multiple temperatures of system elements and thermal resistances between the elements in the model.

[0087] Based on such a model, the temporal progression of temperatures within the system can be predicted for the individual actuators of the system from a 3D trajectory (the temporal progression of the positions). Prediction accuracy can be increased if the model parameters are adjusted based on experimental measurement results. Modeling can also be performed, in particular, for the drive of the focusing axis (z-axis) of the system. This is particularly important because these system components must be operated closer to the limits of their thermal design due to the lower dynamic potential in the overall system.

[0088] In the trajectory planning process, the modeled temperature can be used to establish a limit or optimization criterion. For example, heating can be limited to a maximum temperature, or a function of the temperature can be calculated into a metric that describes the degree of optimality of a solution.

[0089] An optimization goal may also be to ensure a phased heat input so that the temperature of the drive does not fall below a target operating temperature, e.g. with the aim of avoiding temperature drift and thus improving the accuracy of the overall system.

[0090] The planning of a trajectory for a 3D system can be done automatically based on input data that describes:

[0091] • Target geometry (e.g. shape of the track in 3D)

[0092] • Dynamic limits of the actuators and the laser setting

[0093] • Boundary conditions of the process (e.g. speed window)

[0094] • Optimization specifications (e.g. weighting of criteria)

[0095] This input data can vary between different tasks, but it can also be the case that a task consists of several different sections, each of which requires different input data (different parameters and / or different values ​​of parameters).

[0096] It can therefore be useful to design the user interface so that the user describes the machining task as a set or sequence of multiple subtasks, each with its own set of parameters. For this purpose, a program interface can provide commands or macros that describe not only basic geometric elements (such as a single directed line), but also a larger, complex object (such as a hatch fill of a limited area). Here, parameters can describe which target variables in the section are relevant for optimization. For example, tracking accuracy may play a greater role for a contour than for a fill.

[0097] The user interface can also provide functions to automatically divide a machining task into appropriate sections based on analysis of the machining parameters. One useful possible criterion is a key figure that describes the heating of the Z-drive. For example, acceleration in the z-direction can be analyzed by calculating a time average over time windows.

[0098] Optimization can then be carried out in a meaningful way, applying the relevant criteria. As discussed in the other sections, achieving all goals (compliance with all limits) is not always possible. In these cases, automatic adjustment / error correction could be achieved using rules embedded in the algorithm. In practice, however, the effort required to precisely configure such software is too great if all possible exceptions must be handled.

[0099] It is therefore advantageous to provide a user interface that presents the user with an interim planning result and highlights relevant deviations from specifications or the degree to which optimization criteria are met. This can be achieved, for example, through a graphical user interface that displays the path and, for example, uses a color code to highlight areas of the path where problems exist. The user can be given recommendations on how to adapt the planning specifications to achieve better results.

[0100] In particular, it can be suggested to insert an intermediate sequence at a certain point or to reduce the path speed in a certain section in order to have more time in the machining plan to reduce a deviation of the z-coordinate from the target path. Alternatively, it can be suggested to tolerate a deviation at a certain point as an exception. For this purpose, the user interface can also display the temporal progression of control parameters or system variables.

[0101] For this purpose, the user interface can also present the user with key figures that can be generated for the entire processing task or sections of it (e.g. execution time, power consumption, average power, laser utilization rate, ...).

[0102] Such a user interface can enable the user to optimize the control trajectory interactively, manually or semi-automatically - in particular by manually varying default parameters and analyzing the simulated result.

[0103] The user interface can also allow the user to store or adjust information on process relationships, such as the relationship between laser defocusing and the laser power required in the process.

[0104] The user interface may provide means to reorder the sections of the machining task to prevent excessive heat accumulation in the drive by temporally separating sections with a high heat input by a section with a lower heat input, thereby enabling cooling below a critical temperature.

[0105] The user interface can provide means for properly designing the cooling of the scanner assembly. For example, a simulation result of drive heating with different coolant temperatures or different speeds can be provided to select an appropriate temperature (coolant, drive operating point temperature) or to specify a speed for the scanner.

[0106] The user interface can be graphical, a programming library, or formed by input / output files. The intensity distribution in the focus region of a laser beam with high beam quality can be mathematically described using the concept of Gaussian beams. There are also similar or extended common representations for other beam shapes or lower beam quality. The beam diameter of laser beams reaches a minimum in the focus region and varies only slightly along the beam propagation direction within a characteristic length (Rayleigh length). At larger distances from the focus point along the beam direction, the beam diameter can, for example, scale linearly with the distance.

[0107] If the laser beam does not hit the workpiece to be processed at the focal point, the beam diameter and / or the intensity distribution on the workpiece can be calculated from the mathematical models of the laser beam and the distance (defocusing) – the intensity is generally lower when the beam is defocused. Using the calculation and a model or a suitable characteristic curve of the process, a laser power can be determined at which the result of the laser process is more similar to the result achievable with a focused laser (or at another specific target focusing distance other than zero).

[0108] Other values ​​that depend on the current path coordinates or speed can also be included in this calculation. For example, the oblique incidence on the workpiece can be compensated for depending on the location, or the optical properties of the f-theta lens of the scanning system can be compensated.

[0109] Conversely, for example, due to inaccurate alignment of a moving axis of the focusing system during defocusing in the z-direction, a parasitic offset in the x- and y-direction can also occur. If this offset is not already compensated for downstream in the coordinate transformation of the control system, accuracy can be improved by adjusting the x- and y-coordinates of the control values ​​accordingly when planning a defocusing operation to suppress the error.

[0110] Further advantages of the invention are described in the following exemplary embodiments. Figure 1 shows two schematic embodiments of a laser processing device,

[0111] Figure 2 three images with different focus positions of a laser focus,

[0112] Figure 3 shows a schematic example of a movement path,

[0113] Figure 4 shows several diagrams of different courses,

[0114] Figure 5 shows several diagrams of different courses,

[0115] Figure 6 two schematic trajectories on an object and

[0116] Figure 7 shows a diagram of a focus curve with a tolerance range.

[0117] Figure 1 shows two versions of a laser processing device 19. These two versions differ only in that, in the right-hand version, the laser processing device 19 includes a telecentric flat-field optics 18. This is explained in more detail below. Otherwise, the further description of the laser processing device 19 and its features applies to both versions.

[0118] With the laser processing device 19 shown, an object 1 can be processed using a laser beam 2. The processing may involve, for example, welding, cutting, and / or marking the object 1 and / or the local melting of a powder for 3D printing using the LPBF process.

[0119] The laser beam 2 is guided along a movement path 3 to process the object 1. The movement path 3 is shown here as a line for example. However, in general, the movement path 3 can also be curved. For example, the object 1 is welded, cut, and / or marked along the movement path 3.

[0120] In order to guide the laser beam 2 along the movement path 3 and / or over the object 1, the laser processing device 19 comprises a galvo scanning system 4. The laser beam 2 can be deflected and moved by means of the galvo scanning system 4. For this purpose, the galvo scanning system 4 can comprise a first and / or a second deflection mirror 20, 21. The first and / or second deflection mirror 20, 21 can be moved in order to deflect and move the laser beam 2. The two deflection mirrors 20, 21 shown here are advantageous in this case. The first deflection mirror 20 can deflect the laser beam 2 in a first direction and the second deflection mirror 21 can deflect the laser beam in a second direction. The first and / or second deflection mirror 20, 21 can thus be adjusted in an x-direction and y-direction shown here by means of the first and / or second deflection mirror 20, 21.As a result, the laser beam 2 can be guided over the object 1 according to the x-coordinates and y-coordinates of the movement path 3.

[0121] The first and / or second deflection mirror 20, 21 may comprise associated actuators that move the first and / or second deflection mirror 20, 21.

[0122] Furthermore, the galvo scanning system 4 comprises a focus actuator 16, by means of which a focus position of a laser focus 5 of the laser beam 2 can be adjusted along a laser propagation direction 6. By means of the focus actuator 16, the laser focus 5 can be shifted or moved along the laser propagation direction 6. For the laser processing of the object 1, it is advantageous if the laser focus 5 is located in the movement path 3 and is moved along the movement path 3. The quality of the laser processing can decrease if the laser focus 5 is located above or below the movement path 3 and / or the object 1. Above and below refer to the laser propagation direction 6.

[0123] According to the present exemplary embodiment, the galvo scanning system 4 comprises a focusing device 22, which comprises the focus actuator 16. The focusing device 22 further comprises a focusing unit 23, which is moved and / or controlled by the focus actuator 16. By moving the focusing unit 23, the laser focus 5 can be moved along the laser propagation direction 6. The focusing unit 23 can, for example, be and / or comprise a diverging lens, as shown here. However, the focusing unit 23 can also be implemented, for example, by a moving converging lens, in particular in a collimation device. Furthermore, the focusing device 22 can comprise at least one lens 24, shown here. With the aid of the at least one lens 24 shown here, the laser beam 2 can be focused in order to form the laser focus 5.

[0124] In addition, the laser processing device 19 and / or the galvo scanning system 4 according to the embodiment on the right side of Figure 1 includes the telecentric flat-field optics 18. By means of this telecentric flat-field optics 18, the laser beam 2 can be guided perpendicularly onto the object 1. In the embodiment on the left side of Figure 1, no telecentric flat-field optics 18 is present. As a result, the laser beam 2 is guided obliquely onto the object 1. This would also be the case, for example, if a flat-field optics were not used in a non-telecentric arrangement.

[0125] Furthermore, a computing unit 17 is shown, by means of which the laser processing planning and / or the laser processing of the object 1 can be carried out and / or controlled. In this case, the laser processing device 19 can comprise the computing unit 17. The computing unit 17 can further comprise a control unit for controlling the laser processing. Furthermore, the computing unit 17 can also be arranged in a control unit of the laser processing device 19. The laser processing planning and the laser processing can also be carried out by two separate computing units 17. For example, the computing unit 17 can be part of a PC by which the laser processing planning and / or the laser processing is carried out and / or which controls the laser processing planning and / or the laser processing.

[0126] Features that have already been described in at least one previous figure cannot be explained again for the sake of simplicity. Furthermore, features can also be described in this or in at least one of the subsequent figures. Furthermore, for the sake of simplicity, the same reference symbols are used for the same features. Moreover, for the sake of clarity, not all features can be shown and / or provided with a reference symbol in the following figures. However, features shown in one or more of the previous figures can also be present in this or in one or more of the subsequent figures. Furthermore, for the sake of clarity, features can also be shown and / or provided with a reference symbol in this or in one or more of the subsequent figures.Nevertheless, features which are only shown in one or more of the subsequent figures may already be present in this or a previous figure.

[0127] Figure 2 shows three images with different focus positions of the laser focus 5.

[0128] Here, the object 1 and the laser beam 2 are shown. Also shown are the laser propagation direction 6 and the laser focus 5. The laser focus 5 is characterized in that the cross-section of the laser beam 2 is smallest there. In the laser propagation direction 6, the laser beam 2 has a larger cross-section in the area before and after the laser focus 5. For laser processing, it is generally most advantageous if the laser focus 5 is located exactly on an object surface 26 of the object 1 and / or in the movement path 3. In general, the movement path 3 is located in or on the object surface 26. This relationship between the laser focus 5 and the object surface 26 and / or the movement path 3 is shown in the middle illustration. Here, the distance 25 between the laser focus 5 and the object surface 26 and / or the movement path 3 is zero.

[0129] In contrast, the laser focus 5 in the left-hand illustration is arranged in front of the object surface 26 and / or the movement path 3 in the laser propagation direction 6. This creates the distance 25 between the laser focus 5 and the object surface 26 and / or the movement path 3 in the left-hand illustration.

[0130] In the right-hand illustration, the laser focus 5 is arranged behind the object surface 26 and / or the movement path 3 in the laser propagation direction 6. Consequently, the distance 25 is also formed between the laser focus 5 and the object surface 26 and / or the movement path 3.

[0131] The following representations in Figures 3 - 5 illustrate a simple path planning task and the time course of a possible solution. In this example, a path containing two meanders is to be processed. It is assumed in the example that the focusing device 22 of the scanning system is to compensate for the field curvature of a pre-focus scanning system without a flat-field lens. The default path of the z-control coordinate is therefore calculated here using a formula relationship from the x and y values, which is a typical scenario. Processing can be carried out with a laser power in the range of, for example, approximately 20 watts.

[0132] Figure 3 shows an example of a trajectory 3. Trajectory 3 is two-dimensional, ie, with x and y coordinates.

[0133] The movement path 3 has a path start 27 and a path end 28, wherein the laser beam 2 is moved along the movement path 3 from the path start 27 to the path end 28.

[0134] The movement path 3 has at least one processing section 9 and / or at least one jump section 10. In the at least one processing section 9, the object 1 is processed, such as welded, cut, or marked. In the at least one jump section 10, the laser is switched off, so that no processing takes place. The jump section 10 shown here is arranged at the path end 28. In the present example, the jump section 10 shown here serves to guide the switched off and, so to speak, fictitious laser beam 2 to a path start 27 of another movement path 3 or to return the switched off or fictitious laser beam 2 to a waiting position.

[0135] According to the present embodiment, the processing section 9 shown here comprises a first meandering section 14 and a second meandering section 15. An intermediate section 32 is arranged between the two meandering sections 14, 15. In this intermediate section 32, the movement path 3 or the processing path 9 is rectilinear.

[0136] Figures 4 and 5 show the location-dependent, adjusted focus curves 8 of the z-coordinate, which were planned within a tolerance band (dotted line) around the target curve (dashed line). The z-coordinate indicates the focus position of the laser focus 5 along the laser propagation direction 6. The curve is smooth and follows the deflections in the z-direction only to a very limited extent. When controlling the laser, both the focus deviation and the deviation from the specified path speed were taken into account. Figure 5 shows a detailed section in which the correction of the laser power as a function of the deviation of the z-coordinate from the center of the tolerance band and, at the same time, as a function of the path speed is clearly visible. The laser power is increased when the speeds at reversal points of the path are reduced. It is also increased when the deviation from the center of the tolerance band is large.

[0137] The lowest diagram in Figure 4 and Figure 5 shows a predicted temperature curve of the z-drive, which was calculated from the acceleration curve of the adjusted focus curve using a simple model.

[0138] For the purpose of representing the time dependence in the diagrams of Figures 4 and 5, the monotonic relationship s(t) is mathematically inverted with respect to t(s) to represent the location-dependent quantities as a function of time, which is equivalent due to the reversibility of s(t). This corresponds to the form of a control program, such as the computer unit can typically output when controlling the actuators.

[0139] Figures 4 and 5 show several curves 7, 8, 12, 29, 30, 31 that match the trajectory 3 shown as an example in Figure 3. Figure 5 shows a location-dependent speed curve 12, a location-dependent idealized focus curve Zsoii(s) 7, a location-dependent adjusted focus curve 8, a location-dependent power curve 13, and a location-dependent temperature curve 31. In addition to the curves 12, 7, 8, 13, 31 shown in Figure 5, Figure 4 also shows a location-dependent x- and y-coordinate curve 29, 30.

[0140] Figure 5 shows the same courses 12, 7, 8, 13, and 31 in a section and in more detail. Figure 5 shows a section that includes a small area of ​​the first meander section 14, the intermediate section 32, and the largest area of ​​the second meander section 15.

[0141] The two upper diagrams of Figure 4 show an x-coordinate curve 29 and a y-coordinate curve 30 of the movement path 3.

[0142] The two meandering sections 14, 15 are clearly visible in the x-coordinate curve 29 and the y-coordinate curve 30. An idealized focus curve 7 is shown in the fourth diagram from the top in Figure 4 and in the second diagram from the top in Figure 5. The idealized focus curve 7 indicates the focus position of the laser focus 5 in the laser propagation direction 6 along the movement path 3. The idealized focus curve 7 is more clearly visible in Figure 5 and is represented by the dashed line.

[0143] The idealized focus path 7 indicates the optimal focus position of the laser focus 5 along the laser propagation direction 6. According to Figure 5, the idealized focus path 7, particularly in the region of the second meander section 15, also has a zigzag shape, i.e., like the y-coordinate path 30, for example. This can be due, for example, to the fact that the object 1 is curved at least in the region of the second meander section 15 or because the laser beam 2 strikes the object 1 alternately at a flatter and a steeper angle according to the meander shape. If, for example, the angle at which the laser beam 2 strikes the object 1 becomes steeper, the laser focus 5 shifts above the object 1 or above the object surface 26. The laser focus 5 therefore no longer reaches the object 1 or the movement path 3 on the object surface 26.As a result, the focus actuator 16 must move the laser focus 5 along the laser propagation axis 6, further towards the object 1. If the angle at which the laser beam 2 strikes the object 1 becomes smaller again, the laser focus 5 shifts into the object 1, as shown in the right-hand illustration of Figure 2. The focus actuator 16 must therefore move the laser focus 5 again along the laser propagation axis 6, in such a way that it is moved away from the object 1. The focus actuator 16 thus positions the laser focus 5, for example, in relation to the object 1, the movement path 3 and / or the object surface 26. The focus actuator 16 thus sets the focus position of the laser focus 5 in relation to the object 1, the movement path 3 and / or the object surface 26.

[0144] However, the focus actuator 16 cannot adjust the focus position of the laser focus 5 as quickly as desired. For example, due to inertia, the focus actuator 16 can adjust the focus position of the laser focus 5 according to the idealized focus curve z S0 n(s) 7 cannot be mapped 100%. The focus actuator 16 has dynamic limits that prevent the (non-constant) idealized focus curve z S0 n(s) 7 can be achieved. This is of course only true if the idealized focus curve z S0 n(s) 7 is not constant. In the laser processing planning procedure, the idealized location-dependent focus curve Zsoii(s) 7 is extended by a tolerance range 11.

[0145] An adapted focus curve 8 is then determined from the idealized focus curve Zsoii(s) 7 in such a way that at least dynamic limits of the focus actuator 16 for adjusting the focus position of the laser focus 5 are observed and that the adapted focus curve 8 lies at least partially within the tolerance range 11.

[0146] The adjusted focus curve 8 is again clearly shown in Figure 5. With the adjusted focus curve 8, for example, the peaks in the idealized focus curve Zsoii(s) 7 are smoothed. This prevents the focus actuator 16 from having to abruptly change the focus position of the laser focus 5. The adjusted focus curve 8 allows the movement of the focus actuator 16 to be smoother. This prevents overloading of the focus actuator 16. When determining the adjusted focus curve 8, it is taken into account that the tolerance range 11 is not exceeded. The tolerance range 11 can be selected depending on the accuracy to be achieved in the laser processing and / or the properties of the laser beam.

[0147] Furthermore, a speed curve 12 is shown in Figures 4 and 5. This can be determined depending on the location-dependent adjusted focus curve 8. The speed curve 12 specifies a speed of the laser focus 5 along the movement path 3. As can be seen in Figures 4 and 5, the speed curve 12 has reduced areas that are located where the kinks in the idealized focus curve z S0 n(s) 7. As a result, the speed of the laser focus 5 at the bends in the idealized focus path z S0 n(s) 7 is reduced so that it is made available to the focus actuator 16 to adjust the focus position of the laser focus 5.

[0148] Furthermore, a power curve 13 is shown in Figures 4 and 5. This can be determined depending on the adjusted focus curve 8 and / or the speed curve 12. The power curve 13 specifies a power of the laser along the movement path 3. As can be seen in Figures 4 and 5, the power curve 13 has reduced and / or increased areas. This can, for example, compensate for the reduced speed in the speed curve 12. With a reduced speed of the laser focus 5, more energy is also introduced into a path section if the laser power is kept constant. In order to achieve a uniform energy input along the processing path 9, the power curve 13 can be determined.

[0149] Additionally, Figures 4 and 5 show a temperature curve 31. This indicates the temperature of the focus actuator 16 along the movement path 3. This can provide information about whether the focus actuator 16 is overheating or overheating. If, for example, a temperature limit is exceeded, the speed curve 12 can be reduced, particularly in the sections where the temperature limit is exceeded.

[0150] The paths 7, 8, 12, 13, 29, 30, 31 described in Figures 4 and 5 are planned, which preferably takes place before the laser processing of the object 1. The laser processing planning and the laser processing can also take place in parallel, with the trajectory 3 being planned and processed section by section. Thus, a future section of the trajectory 3 can be planned while processing a current and already planned section of the trajectory 3.

[0151] Figure 6 shows two exemplary trajectories 3a, 3b on curved objects 1a, 1b. The letters "ABC" are to be written on both objects 1a, 1b, which can also be laser processed. Both letter combinations have the same trajectory start 27 and the same trajectory end 28.

[0152] Furthermore, both letter combinations have the same processing sections 9a, 9b, and 9c. The first processing section 9a forms the "A," the second processing section 9b forms the "B," and the third processing section 9c forms the "C." The two movement paths 3a, 3b differ in the arranged jump sections 10a-10f.

[0153] For both movement paths 3a, 3b, the movement directions of the laser beam 2 are shown by arrows.

[0154] In the upper movement path 3a on the upper object 1a, the workpiece "A" is processed first, followed by the first limb of "A". This is followed by the first jump section 10a. During the first jump section 10a, the laser is switched off. During the first jump section 10a, the galvo scanning system 4 is controlled such that the laser beam 2 is correctly positioned for processing the bar of "A". After the completion of "A", the second jump section 10b follows, and the workpiece "B" is processed. This is followed by the third jump section 10c, by means of which the laser beam 2 is positioned for processing the "C" on the object 1a.

[0155] The lower object 1a also follows the movement path 3b. In addition to the jump sections 10a - 10c of the first or upper movement path 3a, three further jump sections 10d - 10f are added.

[0156] These three jump sections 10d - 10f are inserted at respective insertion points 33a - 33c. These three jump sections 10d - 10f are coupled out and recoupled at the respective insertion points 33a - 33c. These three jump sections 10d - 10f serve to compensate for the abrupt change in direction, for example, at the tip of the "A". At these points, the focus actuator 16 would also have to abruptly reverse the movement of the laser focus 5, since the curved object 1b first requires the laser focus 5 to be moved toward the object 1b and, after the tip of the "A", must be moved away from the object 1b again. The abrupt reversal of direction places a high load on the focus actuator 16 and cannot be performed by it.By using the jump sections 10d-10f at such locations on the object 1, the focus actuator 16 can be given time to adjust the focus position of the laser focus 5 and accelerate it to the required speed of the focus actuator in order to be able to follow the movement path 3 in the subsequent path section as well. The jump sections 10a-10f are shown here by dotted lines. In the jump sections 10a-10f, no processing of the object 1a, 1b takes place. In the jump sections 10a-10f, the laser can be switched off.

[0157] Figure 7 shows an example of the planning of the local course of a location-dependent, adjusted focus path 8 along an exemplary movement path s(t), whose curvature is minimal in some sections. The location-dependent, adjusted focus path 8 shows the processing sections 9a-9c and the jump sections 10a, 10b, at which the object 1 is processed with the focus positions of the laser focus 5 belonging to the location-dependent, adjusted focus path 8. In the jump sections 10a, 10b, the object 1 is not processed because the laser is or can be switched off here. Alternatively, the laser can also be set to a low power in the jump sections 10a, 10b, so that no processing takes place.

[0158] In areas in which the location-dependent adjusted focus curve 8 increases, for example in the area towards the end in the first processing section 9a, the laser focus 5 is moved further towards the object 1 in order to compensate for the drop in the object 1 due to an object curvature and to keep the laser focus 5 in the movement path 3 and / or on the object 1.

[0159] In this example, the first jump section 10a is inserted at an insertion point 33. The two adjacent processing sections 9a, 9b are directly adjacent to one another on the object 1. For example, the two processing sections 9a, 9b are the two legs of the "A" in Figure 6. The first jump section 10a is then inserted, for example, at the tip of the "A" or at the insertion point 33a there in Figure 6. The second jump section 10b connects the two processing sections 9b, 9c, which are spaced apart from one another on the object 1. This can be seen in particular from the fact that the location-dependent, adjusted focus profile 8 has a jump in the focus position.

[0160] Furthermore, it can be seen that the location-dependent adjusted focus path 8 is within the tolerance range 11. After the location-dependent adjusted focus path 8 has been determined, as shown in Figure 7, with an at least largely minimal curvature fitted into the tolerance range, the speed path 12 along the movement path 3 can be determined in a subsequent planning step, whereby the temporal course of the movement path s(t) is also determined.

[0161] List of reference symbols

[0162] 1 object

[0163] 2 laser beam

[0164] 3 Movement path

[0165] 4 Galvo scanning system

[0166] 5 Laser focus

[0167] 6 Laser propagation direction

[0168] 7 location-dependent idealized focus curve z S0 n(s)

[0169] 8 location-dependent adjusted focus progression

[0170] 9 Processing section

[0171] 10 jump section

[0172] 11 Tolerance range

[0173] 12 location-dependent speed curve

[0174] 13 Location-dependent performance curve

[0175] 14 first meander section

[0176] 15 second meander section

[0177] 16 Focus actuator

[0178] 17 Computing unit

[0179] 18 telecentric flat-field optics

[0180] 19 Laser processing device

[0181] 20 first deflection mirror

[0182] 21 second deflection mirror

[0183] 22 Focusing device

[0184] 23 Focusing unit

[0185] 24 lens

[0186] 25 distance

[0187] 26 Object surface

[0188] 27 start of track

[0189] 28 end of track

[0190] 29 location-dependent x-coordinate progression

[0191] 30 location-dependent y-coordinate progression

[0192] 31 location-dependent temperature curve

[0193] 32 Intermediate section

[0194] 33 Insertion point

Claims

Patent claims 1 . Method, in particular a computer-implemented method, for laser processing planning and / or for laser processing of an object (1), in which a laser beam (2) of a laser can be guided along at least one predetermined movement path (3) on the object (1) by means of a galvo-scanning system (4), in which a location-dependent idealized focus profile z S0 n(s) (7) is determined, which specifies a focus position of a laser focus (5) of the laser beam (2) in a laser propagation direction (6) along the movement path (3), in which the location-dependent idealized focus profile z S0 n(s) (7) is extended by a tolerance range (11 ) and in which the location-dependent idealized focus curve z S0n(s) (7) a location-dependent adapted focus profile (8) is determined in such a way that at least dynamic limits of a focus actuator (16) for adjusting the focus position of the laser focus (5) are maintained and that the location-dependent adapted focus profile (8) lies at least partially within the tolerance range (11).

2. Method according to the preceding claim, characterized in that to determine the location-dependent adapted focus profile (8) the location-dependent idealized focus profile z S0 n(s) (7) is smoothed.

3. Method according to one or more of the preceding claims, characterized in that the location-dependent adapted focus profile (8) is determined in such a way that a section-wise curvature of the location-dependent adapted focus profile (8) is minimal.

4. Method according to one or more of the preceding claims, characterized in that a location-dependent speed profile (12) of the laser focus (5) along the movement path (3) is determined as a function of the location-dependent adapted focus profile (8).

5. Method according to one or more of the preceding claims, characterized in that the location-dependent adapted focus profile (8) and / or the location-dependent speed profile (12) is planned in such a way that at least one acceleration and / or one jerk of the focus actuator (16) is limited and / or lies within the dynamic limits of the focus actuator (16).

6. Method according to one or more of the preceding claims, characterized in that the location-dependent adapted focus profile (8) and / or the location-dependent speed profile (12) is determined in such a way that thermal limits of a focus actuator (16) for adjusting the focus position of the laser focus (5) are maintained.

7. Method according to one or more of the preceding claims, characterized in that in the event of a violation of the tolerance range (11), in particular a violation calculated in advance, by the location-dependent adapted focus profile (8), the location-dependent speed profile (12) is reduced in at least these areas.

8. Method according to one or more of the preceding claims, characterized in that a location-dependent power curve (13) of the laser along the movement path (3) is determined, which is based on the location-dependent speed curve (12) and / or the location-dependent adapted focus curve (8), so that a planned energy input curve along the movement path (3) is achieved.

9. Method according to one or more of the preceding claims, characterized in that a location-dependent temperature profile (31) of the focus actuator (16), in particular simulated before the laser processing, is determined on the basis of the location-dependent adapted focus profile (8) and / or the location-dependent speed profile (12).

10. Method according to one or more of the preceding claims, characterized in that the movement path (3) is planned in such a way that it comprises at least one processing section (9) and at least one jump section (10), wherein in the processing section (9) the object (1) is processed with the laser and in the jump section (10) the laser is switched off and wherein the at least one jump section (10) adjoins the at least one processing section (9), is attached to the processing section (9) in an insertion point (33) and / or connects at least two processing sections (9) to one another.

11. Method according to one or more of the preceding claims, characterized in that the movement path (3) is divided into at least two processing sections (9) in such a way that in the respective processing sections (9) a location-dependent speed profile (12) of the laser focus (5) along the corresponding processing sections (9) can be constantly determined.

12. Method according to one or more of the preceding claims, characterized in that the movement path (3) is divided into at least two processing sections (9) in such a way that in the at least two respective processing sections (9) the location-dependent speed profiles (12) of the laser focus (5) along the corresponding processing sections (9) are different from one another and that the location-dependent speed profile (12) in the jump section (10) is planned in such a way that the location-dependent speed profiles (12) of the processing sections (9) are connected to one another.

13. Method according to one or more of the preceding claims, characterized in that the tolerance range (11), in particular in the at least one processing section (9), is set to a value between 1% and 200%, in particular 20% to 100%, of a Rayleigh length of the laser.

14. Method according to one or more of the preceding claims, characterized in that the tolerance range (11), in particular in at least one processing section (9) and / or in at least one jump section (10), is set at least in sections to be constant and / or location-dependent.

15. Method according to one or more of the preceding claims, characterized in that in the jump section (10) the tolerance range (11) is enlarged and / or disregarded.

16. Method according to one or more of the preceding claims, characterized in that in the at least one jump section (10) the location-dependent adapted focus path (8) arranged therein is planned in such a way that a, in particular continuous and / or movable, transition to the location-dependent adapted focus path (8) of the adjacent processing section (9) is formed.

17. Method according to one or more of the preceding claims, characterized in that the method for laser processing planning, in particular the determination of the location-dependent idealized focus profile z S0 n(s) (7), the location-dependent adapted focus profile (8), the location-dependent speed profile (12), the location-dependent power profile (13) and / or the location-dependent temperature profile (31), before the laser processing of the object (1) and / or for future sections of the movement path (3) during the laser processing of the object (1).

18. Method according to one or more of the preceding claims, characterized in that the laser processing planning is at least partially repeated if the tolerance range (11), the dynamic and / or thermal limits of the focus actuator (16) are violated.

19. Method according to one or more of the preceding claims, characterized in that the method for laser processing planning and / or for laser processing of the object (1) is carried out by a computing unit (17).

20. Computer program which, when executed by a computing unit (17), causes the computing unit (17) to carry out the method according to one or more of the preceding claims.

21. A computer-readable storage medium comprising a computer program, wherein the computer program, when executed by a computing unit (17), causes the computing unit (17) to carry out the method according to one or more of the preceding claims.

22. Laser processing device (19) for laser processing planning and / or for laser processing an object (1) with a laser for laser processing, with a galvo scanning system (4) for guiding a laser beam (2) of the laser over the object (1), wherein the galvo scanning system (4) comprises a focus actuator (16) for setting a focus position of a laser focus (5) of the laser beam (2), and with a computing unit (17), characterized in that the computing unit (17) is designed to carry out the method according to at least one of the preceding claims.

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