A method for machining cavities within a workpiece using a laser machine tool.

Abstract

This invention provides a method for machining cavities within a workpiece using a laser machine tool. [Solution] The machine tool includes a laser source, a laser head, and an optical system for focusing a laser beam to an ablation position on a workpiece and ablating the material at this position, and includes the steps of: a. the laser beam passing through a focusing lens to reach the ablation position; b. each of the machined layers defines a layer of the workpiece having a defined thickness, and the machined layers are machined continuously; c. the laser beam is defined so that it passes through the focusing lens only within the machining focal range to reach all ablation positions in the patch, and the machining direction defines the direction of the laser beam emitted onto the surface to ablate the patch; and d. ablating the material of the workpiece based on the defined machined layers and patches.

Description

Technical Field

[0001] The present invention relates to a method for machining a workpiece by a laser machine tool. The present invention also relates to a machine tool for machining a workpiece (see US Patent Application Publication No. 2019 / 0001436. For related technical backgrounds, reference can be made to Chinese Patent Application Publication No. 117123928, Chinese Patent Application Publication No. 210306265 or Chinese Patent Application Publication No. 113231732.).

[0002] Background Art Laser ablation methods and machine tools for machining parts by lasers are also generally known. Such machine tools can perform laser machining accurately and quickly. The laser beam is emitted by a laser source of the laser machine tool. The laser head includes a scanner for guiding the laser beam. The laser head can be controlled to move in five axes, and thus the laser beam can accurately reach all positions on the workpiece. Since the scanner includes mirrors for deflecting light, the laser beam can be moved at high speed. Therefore, the machining speed of such a machine tool with a scanner is very fast.

[0003] In some applications, high geometric accuracy is required. For example, a cavity has to be machined. Applying such a machine tool without further means cannot achieve the required geometric accuracy. For example, the wall of the machined cavity has a taper instead of being straight, or the edge of the cavity is rounded instead of being sharp.

[0004] Summary of the Invention An object of the present invention is to provide a method and an apparatus for machining a workpiece while improving geometric accuracy and surface quality. In particular, a further object of the present invention is to provide a method and an apparatus for machining a workpiece having straight walls and sharp edges.

[0005] According to the present invention, these objectives are achieved by the features of the independent claims. In addition, further advantageous embodiments can be obtained from the dependent claims and the description.

[0006] The present invention provides a method for machining a workpiece to obtain a part having a desired geometric shape using a laser beam emitted by a laser head incorporated in a machine tool. The machine tool includes a laser source for emitting a laser beam, and the laser head includes an optical system for guiding the laser beam to a defined position on the workpiece. The optical system includes a plurality of mirrors for reflecting the laser beam emitted by the laser source, and a focusing lens for passing the reflected laser beam through and focusing the laser beam to an ablation position on the workpiece to ablate the material at this position. The method includes the steps of defining a machining focal range to be applied to the machining, calculating a plurality of machining layers based on the desired geometric shape of the part by a processing unit, calculating a plurality of patches for each machining layer by the processing unit, and ablating the material of the workpiece based on the defined machining layers and patches. The machining focal range is a subregion centered on the focusing lens, within which the laser beam passes through the focusing lens to reach the ablation position. Each machining layer defines a layer of the workpiece having a defined thickness. The machining layers are machined sequentially. Each patch defines a region on a single machining layer of the workpiece. The region within the patch is machined from a single position of the laser head, particularly while the laser beam is directed to different locations within this region by the optical system. Furthermore, the patch is defined such that the laser beam passes through the focusing lens only within the machining focal range and reaches all locations within the patch. This ensures that the optimal area of ​​the focusing lens is utilized.

[0007] Laser ablation technology is widely used for drilling, cutting, and engraving by sublimation of material, generally metal, on the surface of a workpiece. Machining is performed in several steps, each step corresponding to machining a layer of the workpiece. In practice, with each laser beam pass, the material can sublimate to a certain depth. This depth is usually defined as the removal rate. Typically, the removal rate is in the range of approximately 0.2 to 5 micrometers, particularly 0.2 to 2 micrometers. Therefore, many machining layers are required to obtain the desired geometric shape, such as a cavity or hole. The number of layers is usually several to several hundred. This depends on the depth of the cavity or hole and the removal rate. For example, the number of layers is calculated by dividing the cavity depth by the removal rate. Workpieces can be numerically modeled, usually by triangulation, to generate a 3D modeling file, such as a mesh file. Therefore, the set of machining layers is usually calculated from the 3D modeling file and the geometric shape of the cavity.

[0008] For each machining layer, it is necessary to calculate the set of laser head positions that enable machining of the area of ​​that layer. Typically, the optics used for laser ablation with a focal length of, for example, 430 millimeters, allows machining of a plane measuring, for example, 300 x 300 millimeters, called the field of view, from a given position of the laser head. The dimensions of the field of view are limited by the optics of the machine tool. This means that the area that can be machined from a given position of the laser head is limited, and therefore each machining layer must be divided into multiple patches, each patch being machined from a given position of the laser head. To machine another patch, the laser head must be repositioned by the machine axis. To ablate one patch, the laser head is moved to a predetermined position and remains in this position until the ablation of that patch is complete. However, the optics are controlled to move the laser beam to different positions within this patch. Because the optics is a very fast system, the laser beam can be moved at very high speeds. Therefore, complete machining of a desired geometric shape, such as a cavity or hole, involves ablating multiple machining layers, with each layer having a set of positions the machining head must reach in order to machine patches at each position in the layers in question. Naturally, calculating the laser head positions and machined patches requires enormous computer resources, and depending on the complexity and dimensions of the part, the type of algorithm used, and the number of machining layers, this can take hours or even days. This calculation can generally be performed by a processing unit.

[0009] In one variant, the processing unit is located outside the machine tool, for example, in a specific workstation or computer. The data generated by the processing unit is called machining data. The machining data is transmitted from the processing unit to the machine tool before machining.

[0010] In another variant, the processing unit is integrated into the machine tool. Therefore, calculations for machining layers and patches can be performed directly on the machine tool.

[0011] In particular, machining data is transmitted to a control unit integrated into the machine tool. The control unit is configured to control the machine head and the optical system for ablation. The machining data essentially consists of a machining tool path that includes a series of positions that the laser machining head must occupy relative to the part, and for each position, a series of ablation operations corresponding to the scan that the laser beam must perform from this position.

[0012] A focusing lens is applied to concentrate a laser beam, guided by a mirror, to a single point on the workpiece. However, due to the optical limitations of the focusing lens, the entire area of ​​the focusing lens does not provide a focused laser beam of the same quality. It is advantageous to use the area around the center of the focusing lens so that the laser beam can be optimally focused onto the workpiece through the focusing lens. By designing the patch so that only the optimal area of ​​the focusing lens is used, machining quality can be improved without any additional optical elements.

[0013] In a preferred modification, the patch size is determined considering the machining focal range and the position of the machine head. For example, the patch size can be limited so that only the machining focal range is used to allow the laser beam to pass through so that all patches can be ablated. In this way, the laser beam passing through the focal lens is optimally focused. The goal is to avoid guiding the laser beam outside this defined range to pass through the area of ​​the focal lens, in order to ensure ablation quality. Typically, the entire field of view of the lens is used to transmit the laser beam. However, optical deformation can occur at the edges of the focal lens. For example, if the laser beam passes through the central area of ​​the focal lens, the focal point of the laser beam has an optimal shape, such as a circle. However, if the laser beam passes through an area off-center, the shape of the laser beam spot will differ from the optimal shape, such as an ellipse. The shape of the laser beam spot can have a significant direct impact on the surface quality of the machined part. Changes in the shape of the laser beam spot can cause changes in the ablation depth.

[0014] Therefore, in a preferred modification, the machined focal range is the central region of the focal lens, and in particular the machined focal range is less than 70% of the entire focal lens, preferably less than 50%, and especially less than 25%.

[0015] In this invention, an additional verification step is introduced to optimize machining quality. This step is applied to at least one patch. In this step, the machining direction is verified. For at least one patch, the machining direction is determined. The laser beam direction defines the orientation of the laser beam emitted onto the surface to ablate the patch. Preferably, for each patch, the laser beam direction is determined and verified.

[0016] Since patches are machined from a single position on the laser head, for each patch, the machining direction must be determined based on defined criteria and applied to machine that patch. This machining direction is the direction of the laser beam striking the surface being machined. In practice, the highest quality of laser machining can be achieved when the direction of the laser beam is the normal direction of the surface being ablated. The normal direction is defined as the line perpendicular to the surface at a specific point on a patch. However, it is difficult to determine a patch so that the laser beam always strikes in the normal direction. Therefore, an algorithm is applied to define the direction of the laser beam for each patch based on design constraints.

[0017] The number of patches directly affects machining time, as each patch requires mechanical movement of the machine head. Therefore, the number of patches should be kept as small as possible. In certain areas, such as near walls and edges, it is impossible to determine a single machining direction for ablating all locations within a single patch, for example, due to the geometric shape of the area contained within the patch. Therefore, in a favorable modification, the patch is divided into at least two patches.

[0018] The machining direction is a three-dimensional vector defined by the angle of incidence. The angle of incidence is the angle between the machining direction and the normal direction of the surface.

[0019] Typically, orienting the beam to obtain an incidence angle close to the surface normal is optimal for machining accuracy, especially for machining areas without walls and edges. However, this condition cannot always be met. Furthermore, other conditions for the incidence angle are required for machining areas that include walls and edges. Therefore, a target range for the incidence angle is defined, specifically between 10 and 90 degrees, preferably between 10 and 50 degrees, and particularly between 10 and 30 degrees. Within this range, machining accuracy can be ensured. The incidence angle is also determined during patch calculation. If the incidence angle of one patch is outside the defined range, the patch is recalculated. The goal is to ensure that the incidence angle remains within the specified range for most patches, and especially for all patches.

[0020] In favorable configurations, the target range of the angle of incidence is determined based on the desired geometric shape.

[0021] In one configuration, the range of the incident angle can be selected by the user. This increases the system's flexibility.

[0022] Preferably, the range of the angle of incidence is determined considering the materials of the workpiece and / or the focal lens.

[0023] In one variant, the angle of incidence is determined relative to the patch depending on its location and geometric shape. If the patch is flat, a near-perpendicular angle of incidence is used. If the patch is at the edge of a cavity or close to the cavity wall, the angle of incidence is changed by inclination. This inclination is achieved by the mechanical displacement of the laser head and / or the displacement of the workpiece by moving the mechanical axis of the machine.

[0024] In one favorable modification, if the angle of incidence of one patch is outside the target range of angles of incidence, the patch is recalculated.

[0025] In particular, if the angle of incidence of one patch is outside the target range for the angle of incidence, the patch is divided into at least two patches. Automatic patch division management is linked to the angle of incidence management. For one patch, if it is difficult or impossible to find an angle of incidence that fits the patch's geometry, the patch is divided into smaller patches, and further analysis is repeated for each of these new patches until an appropriate angle of incidence relative to the machining direction can be set for each patch. By applying all of these features, machining accuracy can be dramatically improved.

[0026] The present invention relates to a processing unit for processing machining data supplied to a machine tool for machining a workpiece to obtain a part with a desired geometric shape. The processing unit is configured to define a machining focal range of a focal lens applied to machining, the machining focal range being a sub-region at the center of the focal lens, within which the laser beam passes through the focal lens to reach the ablation locations. The processing unit is configured to calculate a plurality of machining layers based on the desired geometric shape, each machining layer defining a layer of the workpiece having a defined thickness, and the machining layers are machined sequentially. The processing unit is configured to calculate a plurality of patches for each machining layer, each patch defining a region on one machining layer of the workpiece, the region within the patch being machined from a single position of the laser head, the laser beam directed to different ablation locations within this region, and at least one patch being defined such that the laser beam passes through the focal lens only within the machining focal range to reach all ablation locations within the patch. The processing unit is further configured to generate machining data including the machining layers and patches.

[0027] The present invention relates to a machine tool for machining a workpiece to obtain a part having a desired geometric shape by a laser beam. The machine tool includes a laser head, an optical system for directing the laser beam to a defined position on the workpiece, and a control unit that receives machining data processed by a processing unit and controls the machine head to machine a cavity based on the machining data. The laser head includes a laser source for emitting a laser beam. The optical system includes a plurality of mirrors that pass the reflected laser beam and focus the laser beam at an ablation position on the workpiece to ablate the material at this position.

[0028] Hereinafter, a more detailed description of the present invention will be further described. Embodiments are described and explained in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0029] [Figure 1] It is a three-dimensional view of a machine tool. [Figure 2] It is a three-dimensional view of an optical system. [Figure 3] It is a side view of a part having a desired geometric shape. [Figure 4] It is a diagram showing one machining layer including a plurality of patches. [Figure 5] It is a diagram showing a focus lens and a scanning field of view. [Figure 6] It is a diagram showing a limited focus lens region and a limited scanning field of view region. [Figure 7] It is a diagram showing a prior art method. [Figure 8] It is a diagram showing the method of the present invention. [Figure 9] It is a side view of a part having a machining direction. [Figure 10] It is a top view of a part having patches and a diagram showing respective machining directions. [Figure 11] It is a diagram showing a modification of the present invention. [Figure 12]This figure shows another modified example of the present invention.

[0030] Modes for carrying out the invention Figure 1 schematically represents an example configuration of a machine tool 10 for laser ablation. The laser head 1 and components of the machine are positioned relative to each other according to five machine axes, thereby enabling the orientation of the emitted laser beam and the positioning of the laser focal point on the surface of a workpiece to be machined (not shown) placed in the machine. The laser head 1 can be displaced in the three dimensions X, Y, and Z of the Cartesian reference coordinate system. Advantageously, the laser head is also rotatable around a rotation axis (not shown) to obtain higher precision and greater flexibility. For all examples given in the remainder of this disclosure, the laser head is considered to be movable according to five axes, namely three axes in translation and two axes in rotation. The machine tool comprises a laser, optical fiber, or free-space optical system for delivering the laser beam into the optical system.

[0031] Figure 2 schematically illustrates the operation of the optical system. In this example, the laser source is contained within the laser head. However, it is also possible to place the laser source in another part of the machine tool rather than within the laser head. Laser 1 emits a laser beam 2, more specifically a pulsed laser beam. The laser beam 2 is reflected by a mirror 4, which allows the position of the projection point of the laser beam on the surface of the part 20 to be defined according to the X and Y axes of the Cartesian reference coordinate system, respectively. Actuator 8 allows the angular position of the mirror 4 to be controlled. The laser beam also passes through a focal lens 6 with dynamic focus correction, such as an F-theta lens or a telecentric lens. Thus, this device makes it possible to define the impact point 9 of the laser beam on the surface of the workpiece 5 in a plane located within the focal range under consideration.

[0032] Typically, a system used with a focal length of, for example, 430 millimeters, allows the optical system to machine a 300 x 300 millimeter plane, called the marking field, from a given position of the laser head 1. On the other hand, if the surface of the workpiece 5 to be machined is not planar, the focusing ability of the lens limits the field of view in directions X and Y. If the curvature of the part is large, the dimensions of the patch must be reduced. Naturally, this consequently increases the number of different positions occupied by the laser head to perform the ablation job, i.e., the number of patches produced. This is why optical devices for zooming along axis Z have been developed, which allow the focus to be changed along axis Z, enabling the machining of marking fields with a marking depth of + or -80 millimeters. The use of a variable focus device does not eliminate the relative repositioning of the laser head 1 and the part, but it substantially limits the number of such repositionings.

[0033] Figure 3 schematically shows a cross-sectional view of part 20 having the desired geometric shape, which is a cavity. A portion of the material is to be ablated to form a cavity 21 within the part. The dark-colored section also shows the remaining material and the shape of the final part. The lighter-colored section shows the material to be removed. The dotted lines indicate the calculated machined layers, e.g., the first machined layer 31, the second machined layer 32, the third machined layer 33, and the final machined layer 34. Typically, the machined layers are uniformly divided along the vertical direction. However, this does not rule out the possibility of generating non-uniform machined layers.

[0034] Figure 4 shows a single machined layer 33. This machined layer is divided into several patches 41, 42, and 43. The patches may have different shapes and sizes.

[0035] Figure 5 shows how the laser beam 2 passes through the focal lens 6. The laser beam 2 passes through the focal lens. A field of view 3 using the entire area of ​​the focal lens is shown. This is applied in known ways. If the laser beam had to pass through the focal lens area located on the boundary, the quality of the laser beam reaching the part would be dramatically reduced. Therefore, a machining focal range 7 is defined, as shown in Figure 6. This range is a limited area of ​​the focal lens, particularly at the center of the focal lens. The laser beam should pass through only this area so as to ensure ablation quality. The patches are determined so that this condition is met. A drawback is that the field of view is further limited to area 3'. Therefore, the patches are determined to overcome this drawback, for example, by reducing the size of a particular patch.

[0036] Figure 7 shows a conventional technique for machining cavities within a part using laser machining. The material is ablated layer by layer. The layers are not divided into patches. In particular, the machining direction is the same for all layers.

[0037] Figure 8 shows an embodiment of the present invention. Each layer is divided into multiple patches. The machining direction of different patches can vary. Arrows pointing in different directions indicate different machining directions for different patches. For example, the first machined layer 31 includes multiple patches. Each patch is represented by a single short line. The first machining direction 51, the second machining direction 52, and the third machining direction 53 are applied to three different patches on the first machined layer. In particular, the angle of incidence is adapted to be within the target range. This optimizes the machining direction of each patch. This can improve the machining quality of the part.

[0038] However, at specific locations on a part, it is impossible to determine a single machining location and define a patch so that all locations within that patch can be machined. Such examples are shown in Figures 9, 10, 11, and 12.

[0039] Figures 9 and 10 show a single part 20 in a side view and a top view, respectively. The cavity 21 will be machined. Therefore, the material in the shaded area shown in Figure 10 must be removed by ablation. For simplicity, only one machined layer is shown in Figure 10. Furthermore, Figure 10 shows only three patches, not all of them. The machining direction for these patches is indicated by dotted arrows. Since Figures 10, 11, and 12 show top views, the machining directions are also shown as top views. The first patch 41 includes an area along just one wall, and the machining direction can be determined, preferably perpendicular to the wall in the top view. By applying this machining direction, all locations to be ablated within this patch can be optimally machined. The second patch 42 includes an area with two walls perpendicular to each other, i.e., an angle. In order to allow both walls to be machined, the machining direction is determined to be in a direction that has the same angle to both walls, rather than perpendicular to one wall. This direction is not as optimal as the machining direction of the first patch, but it is still possible to machine the entire patch by applying a single machining direction. The third patch 43 includes an area consisting of five walls at the four corners. It is impossible to define a single machining direction to machine the entire patch. To solve this problem, the third patch must be divided into two or even three or more patches.

[0040] Figures 11 and 12 show two variations of dividing the third patch. In Figure 11, the third patch 43 is divided into two patches, namely the fourth patch 44 and the fifth patch 45. For each patch, a machining direction can be determined. However, the machining direction is still not the optimal machining direction. To improve machining quality, the fourth patch 44 is again divided into two patches, namely the sixth patch 46 and the seventh patch 47. The fifth patch is also divided into two patches. For each of these patches, one optimal machining direction can be determined. This area is divided into four patches instead of one patch 43. By applying the method of the present invention, machining quality can be improved. For example, a cavity manufactured using the prior art method does not feature straight walls, zero taper angles, and sharp edges as needed. However, a machined part using the method of the present invention can produce straight walls with zero or controlled taper angles and sharp edges. [Explanation of Symbols]

[0041] 1 Laser head 2 laser beams 2' laser 3 field of view 3' Limited field of view 4 Mirror 5 workpieces 6-focus lens 7. Machining focus range 8 Actuators 9 Impact points 10 Machine tools 20 parts 21 Cavity formed 22 First side wall 23 Second side wall 24 Upper edge 25 Lower edge 31 First machined layer 32 Second machining layer 33 Third machining layer 34 Final machining layer 41 Patch 1 42. Second Patch 43. Third Patch 44. Patch 4 45 Patch 5 46. ​​Patch 6 47 Patch 7 50 Machining direction 51 First machining direction 52 Second machining direction 53 Third machining direction

Claims

1. A method for machining a workpiece (5) to obtain a part (20) having a desired geometric shape by a laser beam (2) emitted by a laser head (1) incorporated in a machine tool (10), wherein the machine tool (10) includes a laser source (2') for emitting a laser beam (2), the laser head (1) includes an optical system for guiding the laser beam (2) onto the workpiece (5), the optical system including a plurality of mirrors (4) for reflecting the laser beam (2) emitted by the laser source (2'), and a focusing lens (6) for passing the reflected laser beam (2) and focusing the laser beam (2) onto an ablation location on the workpiece (5) to ablate the material at that location, a. A step of defining a machining focal range (7) for the focal lens (6) applied for machining, wherein the machining focal range (7) is a partial region of the center of the focal lens, and within this region, the laser beam (2) passes through the focal lens (6) to reach the ablation position. b. A step of calculating a plurality of machined layers (31, 32, 33, 34) based on the desired geometric shape of the part (20) by a processing unit, wherein each of the machined layers (31, 32, 33, 34) defines a layer of the workpiece (5) having a defined thickness, and the machined layers (31, 32, 33, 34) are machined in succession. c. A step in which the processing unit calculates for each of the machined layers (31, 32, 33, 34) a plurality of patches (41, 42, 43, 44, 45, 46, 47), each defining a region on one layer of the workpiece (5), wherein the region within the patch (41, 42, 43, 44, 45, 46, 47) is machined from a single position of the laser head (1) while the laser beam (2) is directed to different ablation positions within the region, and the patch (41, 42, 43, 44, 45, 46, 47) is machined from the laser beam (2) to the focal The steps include: defining a point lens (6) so as to pass only within the machining focal range (7) to reach all of the ablation locations on the patches (41, 42, 43, 44, 45, 46, 47); determining a machining direction (50, 51, 52, 53) for at least one of the patches (41, 42, 43, 44, 45, 46, 47); and defining the direction of the laser beam (2) radiated onto the surface to ablate the patches (41, 42, 43, 44, 45, 46, 47); d. A method characterized by the step of ablating the material of the workpiece (5) based on the defined machined layers (31, 32, 33, 34) and the patches (41, 42, 43, 44, 45, 46, 47).

2. The method according to claim 1, wherein the patches (41, 42, 43, 44, 45, 46, 47) are determined taking into consideration the machining focus range (7) and the position of the machine head.

3. The method according to claim 1 or 2, wherein the machining direction (50, 51, 52, 53) is determined for each patch (41, 42, 43, 44, 45, 46, 47).

4. The method according to claim 1, 2, or 3, wherein if it is impossible to determine one machining direction (50, 51, 52, 53) for ablating all locations within one patch (41, 42, 43, 44, 45, 46, 47), the patch (41, 42, 43, 44, 45, 46, 47) is divided into at least two patches (41, 42, 43, 44, 45, 46, 47).

5. The method according to claim 3 or 4, wherein the machining direction (50, 51, 52, 53) is defined by an angle of incidence, and the angle of incidence is the angle between the machining direction (50, 51, 52, 53) and the normal to the patch (41, 42, 43, 44, 45, 46, 47).

6. The method according to claim 5, wherein for at least one patch (41, 42, 43, 44, 45, 46, 47), the angle of incidence is calculated, a target range of the angle of incidence is defined, and for at least one patch (41, 42, 43, 44, 45, 46, 47), the patch (41, 42, 43, 44, 45, 46, 47) is determined such that the angle of incidence is within the target range of the angle of incidence.

7. The method according to claim 5 or 6, wherein if the angle of incidence of at least one patch (41, 42, 43, 44, 45, 46, 47) is outside the target range of the angle of incidence, the at least one patch (41, 42, 43, 44, 45, 46, 47) is recalculated, and in particular the patch (41, 42, 43, 44, 45, 46, 47) is divided into at least two patches (41, 42, 43, 44, 45, 46, 47).

8. The method according to claim 6 or 7, wherein the target range of the incidence angle is determined based on the desired geometric shape.

9. A processing unit for processing machining data supplied to a machine tool (10) for machining a workpiece (5) in order to obtain a part (20) having a desired geometric shape, particularly a cavity (21) or hole, wherein the processing unit a. Define a machining focal range (7) for the focal lens (6) applied for machining, wherein the machining focal range (7) is a partial region of the center of the focal lens, and within this region, the laser beam (2) passes through the focal lens (6) to reach the ablation position. b. Based on the geometric shapes of the workpiece (5) and the cavity (21), a plurality of machined layers (31, 32, 33, 34) are calculated, each of the machined layers (31, 32, 33, 34) defines a layer of the workpiece (5) having a defined thickness, and the machined layers (31, 32, 33, 34) are intended to be machined continuously. c. For each of the machined layers (31, 32, 33, 34), a plurality of patches (41, 42, 43, 44, 45, 46, 47) are calculated, each defining a region on one layer of the workpiece (5), and the region within each patch (41, 42, 43, 44, 45, 46, 47) is machined from a single position on the laser head (1) while the laser beam (2) is directed to different ablation positions within the region, and at least one patch (41, 42, 43, 44, 45, 46, 47) is machined from the laser beam (2) to the machining focal range The machining direction (50, 51, 52, 53) is defined so as to pass through the focal lens (6) only within the enclosure (7) and reach all of the ablation locations within the patches (41, 42, 43, 44, 45, 46, 47), and the machining direction (50, 51, 52, 53) is determined for at least one of the patches (41, 42, 43, 44, 45, 46, 47), and the machining direction (50, 51, 52, 53) defines the direction of the laser beam (2) radiated onto the surface to ablate the patches (41, 42, 43, 44, 45, 46, 47), d. A processing unit characterized by generating machining data including the machined layers (31, 32, 33, 34) and the patches (41, 42, 43, 44, 45, 46, 47).

10. A machine tool (10) for machining a workpiece (5) to obtain a part (20) having a desired geometric shape using a laser beam (2), a. A laser source (2') for emitting the laser beam (2), b. A laser head (1) including an optical system for guiding the laser beam (2) to a defined position on the workpiece (5), wherein the optical system includes a plurality of mirrors (4) for reflecting the laser beam (2) emitted by the laser source (2'), and a focusing lens (6) for passing the reflected laser beam (2) through and focusing the laser beam (2) to an ablation position on the workpiece (5) to ablate the material at this position, c. A machine tool (10) comprising: a control unit for receiving the machining data processed by the processing unit described in claim 9 and controlling the laser head (1) to machine the workpiece (5) based on the machining data.

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