WO2023186951A1

WO2023186951A1 - Deflection device for a laser machining head, and laser machining head comprising same

Info

Publication number: WO2023186951A1
Application number: PCT/EP2023/058076
Authority: WO
Inventors: David Blázquez-Sánchez
Original assignee: Precitec Gmbh & Co. Kg
Priority date: 2022-03-29
Filing date: 2023-03-29
Publication date: 2023-10-05
Also published as: DE102022107324A1; DE102022107324B4

Abstract

The invention relates to a deflection device (30) for a laser machining head (1), which device is intended for generating a parallel offset (d, dx, dy) of a machining laser beam (6) and comprises: at least one plate (30a), wherein the plate (30a) can be tilted about at least one axis (30d) parallel to the plate plane (30b); and an actuator for tilting the plate (30a), wherein a tilt angle (θ) of the plate (30a) about the axis (30d) is limited to at most 30°.

Description

Deflection device for a laser processing head and laser processing head with the same

The present invention relates to a deflection device for a laser processing head for generating a beam offset of a processing laser beam and a laser processing head for processing a workpiece by means of a processing laser beam comprising the same.

background

The controlled deflection of a processing laser beam plays a major role from various aspects of laser material processing, for example for beam path correction or for aligning the processing laser beam, in particular for centering it, in relation to an exit port of a laser processing head or to an optical axis of an optical element, e.g Focusing optics. Another aspect is the dynamic or oscillating deflection of the processing laser beam, for example to carry out a so-called wobbling movement, which has proven to be advantageous for various laser applications such as cutting or welding.

Quality criteria in laser material processing therefore require precise control of the lateral position of the focused processing laser beam. For example, laser processing heads, such as cutting or welding heads, generally require a horizontal or lateral alignment of the laser beam to the center of an exit port or nozzle, for example beam centering. Some prior art laser processing heads include mechanical components that can be moved to mechanically align a nozzle with the laser beam. Alternatively, the processing laser beam can be aimed at the nozzle using a lens, such as a focusing or collimating lens, which can be moved laterally.

The complexity of the alignment depends in particular on the degrees of freedom of the focus of the processing laser beam. For example, in 2D laser cutting, an automatic adjustment of the vertical position of the focus (ie in the direction of propagation of the machining tung laser beam) may be required, while with 3D cutting an additional adjustment may be required, for example with regard to an axis of rotation. However, other laser processing heads allow the focus diameter to be adjusted, which leads to a similar situation.

Although the translation of a mechanical part, i.e. a module of the laser processing head, in relation to the rest of the laser processing head is a simple concept, this has some disadvantages for components with increasing weight, particularly due to the mobility or acceleration requirements in applications such as flatbed cutting.

Depending on how the optical design of the laser processing head is designed and depending on the resulting degrees of freedom for the processing laser beam, alignment using a lens can also have some disadvantages. Disadvantages arise, for example, when the lens is moved axially and/or radially for a purpose other than the central alignment of the processing laser beam, for example to adjust the vertical focus position or to adjust the beam diameter of the processing laser beam. In this case, an additional lateral adjustment of the lens can prove to be complicated and time-consuming. An optical design with an additional lens for lateral alignment of the processing laser beam also increases the complexity.

When processing materials by means of welding and/or cutting, oscillating laser beams have proven to be advantageous for various laser applications. Laser processing heads with mirror scanners are known for such applications, for example from US 2016/0368089 Al and US 2018/0369964 Al. Although mirror scanners are widely used, they have some disadvantages for laser material applications. For process monitoring, a high reflectivity of the mirror over a wide spectral range is desired. In such a case, metallic coatings containing a layer of silver or gold are often used. Such coatings result in higher laser absorption, which can limit the maximum laser power. Alternatively, in the prior art, for example in DE 10 2007 012 695 Al and DE 10 2018221 203 Al, plane-parallel plates for deflecting a laser beam are mentioned, the surface normal of which is arranged at an angle to the beam propagation direction of the incident laser beam. However, the relationship between the focus shift or deflection of the processing laser beam and the angle is generally not linear. This non-linear dependency must be taken into account when controlling an actuator of the plate in order to set the angle required for a desired displacement.

Summary of the invention

It is therefore an object of the present invention to provide a deflection device and a laser processing head therewith for easy and precise control of the lateral position of a processing laser beam on a workpiece.

A further object is to provide a deflection device and a laser processing head with the same in order to efficiently and precisely achieve a lateral alignment of the processing laser beam, in particular for centering, with respect to the laser processing head. In particular, in a laser processing head with at least one (axially and/or radially) movable, refractive optical element, it is a task to achieve a lateral adjustment of the position of the processing laser beam on a workpiece independently of the optical element or independently of mechanical parts of the laser processing head under load make possible.

In addition, it is an object of the present invention to provide a deflection device and a laser processing head therewith in order to achieve dynamic lateral alignment of the processing laser beam, i.e. a wobbling movement, efficiently and precisely.

Another task is to provide a deflection device that is easy to integrate and compact.

At least one of these tasks is solved by the subject matter of the independent claims. According to one aspect, a deflection device for a laser processing head for lateral deflection of a processing laser beam or for generating a beam offset of a processing laser beam comprises: at least one plate, wherein the plate can be tilted about at least one axis parallel to the plate plane; and an actuator for tilting the plate; wherein a tilt angle of the plate about the axis is set to a predetermined angular range of -30° to +30°, in particular to an angular range of -20° to +20° or even to an angular range of -15° to +15° or -10 ° to +10°, limited or limited. In other words, an amount of the tilt angle is limited to a maximum of 30°, in particular to a maximum of 20°, 15° or even 10°. The plate level can also be referred to as the plate center level. The deflection device is therefore set up to bring about a beam offset in a plane perpendicular to the beam propagation direction. The deflection device can therefore also be used as a horizontal deflection or Alignment module can be called.

In the present disclosure, a lateral or horizontal orientation or position may refer to an orientation or position in a plane perpendicular to the propagation direction of the processing laser beam (at that point). The plate can also be referred to as plane-parallel or as a window. In particular, the plate can have two optical surfaces that run parallel to one another. Since the beam propagation direction of the processing laser beam is parallel offset when entering the plate and exiting the plate, it can be referred to as a parallel offset. In other words, a beam offset can be generated without changing the direction of beam propagation.

An advantage of the deflection device according to the invention is that it enables simple control of the lateral position of a processing laser beam. Since the tilt angle of the plate is limited to a range of -30° to +30°, a lateral displacement or beam offset of the processing laser beam is generated, which is in a substantially linear or at least almost linear relationship with the tilt angle. A dependence of the beam offset generated by the deflection device on the associated tilt angle can therefore be described by a linear approximation with an error of less than or equal to 10%. In this way it will the adjustment of the beam offset is made easier, in particular an adjustment of the beam offset is made possible linearly or proportionally to the adjustment of the tilt angle. The handling of a laser processing head can also be improved, since optics, i.e. in particular lenses and/or mirrors, or parts do not have to be moved and/or tilted under load, but rather only a plate which has no further functions and therefore only needs to be tilted serves a precise and easily controllable horizontal beam offset. Limiting the amount of the tilt angle to a maximum value of approximately 30°, which is relatively small, also has the advantage of a compact design. This makes it easier to integrate the deflection device into a laser processing head.

The one- or two-dimensional beam offset generated by the deflection device in a plane perpendicular to the beam propagation direction can be used for beam centering of the processing laser beam in relation to the laser processing head or parts thereof and/or for a dynamic or oscillating beam movement (wobbling movement) of the processing beam for laser processing.

In the case of a laser head with at least one optical element that has a refractive power and that is axially and/or radially movable with respect to the central longitudinal axis, a lateral adjustment of the beam position is independent of this optical element and independent of other mechanical parts that may be under load , particularly advantageous for achieving precise and correct alignment. A significant advantage of the deflection device therefore results from the independence of the beam offset from the movable optics, which makes the deflection device suitable as a modular element for aligning the processing laser beam in a laser processing head. The deflection device can therefore be integrated particularly easily into different laser processing heads, provided these are designed as modular systems.

The deflection device may include a controller that is set up to control the actuator based on a linear approximation between the tilt angle and the beam offset. The plate can be transparent or transmissive or consist of a transparent or transmissive material. The plate can have a refractive index other than 1. In other words, the plate can comprise or consist of a material that has a refractive index not equal to 1. Furthermore, the plate can have or consist of a transparent material, such as quartz glass or another material commonly used for optical elements. The plate can in particular be transparent for the entire wavelength range of the processing laser beam. Otherwise, the plate can only be partially transparent to the processing laser beam, with the processing laser beam having a wavelength range in the visible range and/or in the infrared range.

The plate can be in the shape of a cylinder or a cuboid (with a low height). The plate has optical surfaces, i.e. surfaces through which the processing laser beam passes, the optical surfaces running parallel to one another and lying opposite one another. The plate can therefore be described as plane-parallel.

The axis about which the plate can be tilted is parallel to the plane of the plate. In particular, the axis runs parallel to the optical surfaces of the plane-parallel plate. The plate plane of a (plane-parallel) plate runs parallel to its optical surfaces and lies in the middle between the two opposite optical surfaces. The axis about which the plate can be tilted can, for example, lie on one of the optical surfaces or between the two optical surfaces of the plate, in particular in the plane of the plate. The axis can in particular run through a (volume) center or geometric center of gravity of the plate.

The tilt angle is defined as the angle between the surface normal of the plate (or surface normal or perpendicular to the plate plane), also called the plate normal, in the zero position and the surface normal of the plate in a tilted position. In an installed state of the deflection device, the surface normal of the plate in the zero position preferably runs in such a way that the incident processing laser beam and the emerging processing laser beam run coaxially with one another, ie so that no beam offset occurs. In other words, the surface normal of the plate can be parallel or coaxial in the zero position must be aligned with the beam propagation direction of the processing laser beam, ie the processing laser beam hits the plate perpendicularly in the zero position. When the deflection device is installed, the surface normal of the plate in the zero position can run parallel or coaxial to the beam path of the laser processing head or parallel to the optical longitudinal axis of the laser processing head and / or parallel to the optical axis of a movable optics of the laser processing head (in each case at the position of the deflection guide caution).

The surface normal of the plate in the zero position can run parallel or coaxial to a central longitudinal axis of the deflection device. The deflection device can comprise a housing frame in which the plate is mounted in a tiltable manner. The housing frame can be essentially hollow cylindrical. The central longitudinal axis of the deflection device can correspond to the central longitudinal axis of the housing frame. The plate, in particular the optical surfaces of the plate, can run perpendicular to the central longitudinal axis of the deflection device or to the central longitudinal axis of the housing frame in the zero position.

The deflection device can preferably be set up to deflect the processing laser beam in a range between 0 and approximately ±0.5 mm or to set a beam offset of the processing laser beam in a range between 0 and approximately ±0.5 mm. In particular, the deflection device can be set up to deflect the processing laser beam in a range between 0 and approximately ±0.5 mm or to set a beam offset of the processing laser beam in a range between 0 and approximately ±0.5 mm. In other words, the deflection device is set up to shift an incident beam by up to ±0.5 mm perpendicular to the direction of beam propagation. A beam emerging from the deflection device can thus be displaced by up to ±0.5 mm perpendicular to the beam propagation direction with respect to the beam incident into the deflection device. Since the beam offset occurs parallel to the beam propagation direction, a size or amplitude of the deflection can be independent of a distance to the workpiece. Depending on the magnification of the subsequent optical elements, the deflection device can deflect the processing laser beam in one area between 0 and about ±1.5 mm or even between 0 and about ±2.5 mm can be achieved on the workpiece.

Beam offset means the displacement of the processing laser beam emerging from the deflection device or plate perpendicular to the beam propagation direction with respect to the processing laser beam entering the deflection device or plate. The result of this is that the processing laser beam before the offset has a propagation direction that is parallel to the propagation direction after the offset. If the laser processing head is aligned vertically with its central longitudinal axis and the processing laser beam runs essentially parallel to it, i.e. also vertically, the processing laser beam is offset horizontally by the plate while maintaining the vertical direction of propagation.

The at least one axis parallel to the plate plane can include a first axis and a second axis. The deflection device can therefore comprise a plate which can be tilted independently about two mutually perpendicular axes. In other words, the plate can be tiltable about a first axis parallel to the plate plane with a first tilt angle and about a second axis parallel to the plate plane with a second tilt angle. The second axis can be arranged perpendicular to the first axis. The first tilt angle and/or the second tilt angle can be limited to a range of -30° to +30°. The first axis and the second axis are preferably both parallel to or even in the plate plane, in particular between the two plane-parallel optical surfaces of the plate.

The deflection device includes an actuator for tilting the plate. The actuator may include a piezoelectric, a galvanometric drive and/or a motor.

The deflection device with a plate that can be tilted about two mutually perpendicular axes can therefore be used for two-dimensional alignment or deflection of the processing laser beam perpendicular to the direction of beam propagation. By limiting the two tilt angles, the beam offset is proportional in both dimensions, in particular approximately linearly, to the respective tilt angle of the plane-parallel plates. The embodiment of the deflection device with a single plate that can be tilted about one or two axes for one- or two-dimensional beam offset is extremely space-saving and compact and therefore easy to integrate.

In general, an inclined plane-parallel plate only leads to a lateral shift in the focus position if it is arranged in a divergent or convergent laser beam. Laser processing heads usually have a collimated area between a collimation optics and a focusing optics, therefore the deflection device is preferably placed in front of the collimation optics or after the focusing optics. Integration is particularly difficult with laser cutting heads for high laser powers or with small focal lengths of the focusing optics or collimation optics. High performance water-cooled fiber connectors can also be bulky, resulting in a tight space between an entry port or the end of an optical fiber and the collimating optics. Other parts that further reduce the integration space are protective windows and/or water-cooled hard shutters in front of the collimation optics. After the focusing optics, additional protective windows and especially the gas supply for laser cutting leave little scope for integrating a tilted plane-parallel window. Because of the lack of space, a single plate that can be tilted around two axes is particularly advantageous for integration into laser processing heads.

The deflection device can also comprise two plates (or more), each of which can be tilted about (exactly or at least) an axis parallel to the corresponding plate plane. In other words, the deflection device can comprise: a first plate that can be tilted about (exactly or at least) a first axis parallel to the plate plane with a first tilt angle; and a second plate which is tiltable about (exactly or at least) a second axis parallel to the plate plane with a second tilt angle. The first plate and the second plate are parallel to each other when both plates are in the zero position. The second axis can be arranged perpendicular to the first axis. The first tilt angle and/or the second tilt angle can each be set to the predetermined angular range of -30° to +30°, in particular to an angular range of -20° to +20° or even to an angular range of -15° to +15°, be limited. The first axis can be parallel to or even in the first plate plane, in particular in the first plate. lie and the second axis can lie parallel to or even in the second plate plane, in particular in the second plate.

Using a deflection device with two plates for a two-dimensional beam offset, i.e. for a beam offset in two orthogonal directions, dynamic beam deflection can be achieved with high precision even for high frequencies, e.g. in the kHz range. This has the advantage that a particularly precise beam oscillation or wobbling movement of the processing laser beam can be generated for laser processing, for example laser welding or cutting.

The first plate and the second plate can be arranged directly one behind the other, i.e. without another optical element in between. The first and second plates can be arranged in a housing frame of the deflection device, i.e. in a common holder. In a laser processing head, the first plate and the second plate can be arranged such that an intermediate focus of the processing laser beam lies therebetween. The first and second panels may have identical materials and dimensions. Alternatively, the two plates can also differ in material and/or dimensions.

The actuator of the deflection device can be set up to tilt both plates. Alternatively, the deflection device can have two separate actuators, each of which is set up to tilt one of the flaps.

The first and/or second plates may have the same properties as the plate of the deflection device in the embodiment with only one plate.

The at least one plate can have a thickness of less than or equal to 5 mm, preferably less than or equal to 3 mm, and/or a refractive index of 1.458. Plates of this dimension produce a reliable beam offset of the magnitude that is desired or required for the alignment, in particular the centering and/or the dynamic deflection of the processing laser beam. Furthermore, these plates are inexpensive and available in stores. On the one hand, thinner plates have a cost or weight advantage, on the other hand the offset is smaller due to a thin plate. With a thicker plate, however, a larger area is available for the offset that can be achieved, ie a larger area in which an offset can be caused by tilting the plate. However, a thick plate has a disadvantage in terms of weight and space. The plate thickness can therefore be selected according to a desired range for the offset that can be achieved by the plate. In other words, by selecting a plate with a specific thickness, a range of achievable offset can be specified.

The deflection device can further comprise at least one stop device. The stop device can be set up to limit a (possible or maximum) tilting angle of the at least one plate (i.e. the one plate or the first and second plates) to a predetermined angular range of -30° to +30°. The stop device can be set up to block tilting of the plate by a tilting angle outside the predetermined angular range or to limit or restrict tilting of the plate to the predetermined angular range. The stopping device can therefore define or set the predetermined angular range. The stop device can prevent the plate from tilting by a tilt angle amount of more than 30°, so that the beam offset of the processing laser beam remains substantially linear to the tilt angle.

The stopping device can be a mechanical and/or an electrical lock. The stop device can, for example, be part of a holder for the plate or part of a housing frame of the deflection device. The stop device can mechanically prevent the plate from being tilted by a tilt angle outside the predetermined angular range. This can prevent a greater beam offset in the non-linear range, for example due to incorrect control or due to mechanical influences. The stop device can be designed as a collar or projection to block an outer edge of the plate so that the plate cannot be tilted or rotated further than the predetermined tilt angle range. Additionally or alternatively, the tilt angle range can be limited by controlling the deflection device and/or by a control device of the laser processing head. The specified tilt angle range can be set, for example, through appropriate programming.

According to a further aspect, a laser processing head for processing a workpiece with a processing laser beam, for example a laser cutting head or a laser welding head, comprises: a housing with an entry port for introducing the processing laser beam into the laser processing head and an exit port for exporting the processing beam from the laser processing head, wherein a beam path between the Entry port and the exit port are defined, for example by optical elements or optics; at least one optics arranged movably in the beam path; and at least one deflection device arranged in the beam path according to one of the embodiments described herein.

A laser processing head with one of the deflection devices described has all the advantages and technical effects already described that the respective deflection device has.

The laser processing head can include collimation and focusing optics. The at least one deflection device can be arranged between the entry port and the collimation optics and/or between the focusing optics and the exit port. The at least one deflection device can be arranged in a divergent and/or in a convergent region of the beam path.

The laser processing head can further comprise an optical arrangement for generating an intermediate focus between the collimation and focusing optics. The optical arrangement can also be referred to as an optical relay system. In this way, enough space is created for integration of the deflection device. The optical arrangement can therefore serve to further improve the integration of the deflection device. The optical arrangement can be or form an afocal magnification system with a magnification of -1. The The optical arrangement can, for example, consist of two identical lenses with the same focal length. At least one deflection device can be arranged within the optical arrangement or between the converging lens and the diverging lens. In particular, a plate of the deflection device can be arranged between the converging lens and the intermediate focus and/or a plate of the deflection device can be arranged between the intermediate focus and the diverging lens. For example, a deflection device with two plates that can each be tilted about an axis can be arranged in such a way that the first plate is arranged between the converging lens and the intermediate focus and the second plate is arranged between the intermediate focus and the diverging lens. This allows the modularity and integration of the deflection device into the laser processing head to be improved.

The movably arranged optics have an optical axis which preferably runs along or parallel to the central longitudinal axis of the housing of the laser processing head (at this point) and thus along or parallel to the beam path. Preferably, the beam path can run along the central longitudinal axis of the housing of the laser processing head, the central longitudinal axis essentially coinciding with the optical axis of at least one of the optics arranged in the beam path, in particular the movably arranged optics. However, in the case of laser processing heads with several housing parts that are movable or adjustable relative to one another, deviations can arise, for example due to optomechanical tolerances or misalignments between different housing parts. The deflection device can correct such a deviation by means of a beam offset if, for example, the processing laser beam does not correctly impinge on an optic and/or does not run along the central longitudinal axis of the housing part.

The deflection device can be used modularly in the laser processing head. The laser processing head can thus be subsequently equipped with the deflection device, so that the quality of the laser processing can be further improved even with an already existing laser processing head. The laser processing head can have one or more ports for receiving one or more deflection devices in the beam path. The movably arranged optics can be arranged to be movable radially and/or axially. In particular, the optics can be arranged to be displaceable or movable along the beam path and/or along the central longitudinal axis of the laser processing head and/or along its own optical axis. Alternatively or additionally, the optics can be arranged to be movable in a circle around the longitudinal axis. The movably arranged optics can in particular be refracting and/or beam-shaping optics.

In this disclosure, optics may refer to a lens group, a lens, a mirror, a beam splitter, and/or other optical elements. The optics can in particular comprise a lens, for example a converging lens, a focusing lens, a collimation lens or a diverging lens, or the optics can comprise a lens group of such lenses or combinations thereof.

The entry port can include a coupling device, e.g. a fiber coupler. The exit port may refer to an exit opening. The housing of the laser processing head can include a nozzle or outlet nozzle in which the outlet port or outlet opening is arranged. The laser processing head or the housing can have a central longitudinal axis that runs through the entry port and the exit port. The housing can have a plurality of housing parts that are movable or adjustable relative to one another and each have a central longitudinal axis section. The central longitudinal axis can therefore have several sections that are arranged at an angle to one another. The laser processing head may have a protective glass at the entry port and/or a protective glass at the exit port.

The laser processing head can be, for example, a cutting head and/or a welding head.

The at least one deflection device can be arranged between the entry port and the movable optics and/or between the movable optics and the exit port. In particular, the deflection device can be arranged immediately after the entry port in the beam path, ie before the first refracting and/or reflecting optical see element or in front of the first lens. If the entry port has a protective glass, the deflection device can be arranged immediately after the protective glass. Additionally or alternatively, the deflection device can be arranged immediately before the exit port in the beam path, ie after the last refracting or reflecting optical element or after the last lens. If the exit port has a protective glass, the deflection device can be arranged directly in front of the protective glass.

In the area immediately behind the entry port, the processing laser beam can be divergent and it can be advantageous to generate a beam offset or beam offset of the processing laser beam at this position in order to center it on the central longitudinal axis, so that the following optics, in particular lenses, are as central as possible in the beam path and along whose optical axes the processing laser steel passes through. This can be advantageous if the processing laser beam is not coupled centrally into the housing of the laser processing head. This can prevent the processing laser steel from experiencing an aberration or being refracted away from the beam path due to a decentralized position or a decentralized course relative to a lens. In other words, the deflection device at the position between the entry port and the movable optics can center the processing laser beam on the beam path or on the central longitudinal axis of the housing or the laser processing head, so that each optics can be passed through in a well-defined manner along the optical axis by the processing laser beam.

In the area immediately in front of the exit port, the processing laser beam can be convergent and it can be advantageous to generate a beam offset or parallel offset of the processing laser beam at this position. In the area behind the movable optics and in front of the exit port, the processing laser beam can be centered by the beam offset so that it runs centrally along the longitudinal axis, in particular centrally through an exit nozzle, and hits a workpiece at a well-defined position. This can be particularly advantageous if an optic, for example the movable optics, is misaligned in the laser processing head. For example, a lens may have been accidentally placed decentralized to the central longitudinal axis or may have been displaced by vibrations during processing. In this case, the deflection device behind the movable optics can correct such a misalignment by shifting the beam.

The at least one deflection device can be arranged in a divergent and/or in a convergent region of the beam path. A divergent or convergent area is an area in which the processing laser beam is present as a divergent or convergent beam, i.e. outside a region of the beam path in which the processing laser beam runs parallel or collimated, and outside an intermediate focus or a virtual focus.

In a divergent or a convergent area, the deflection device can produce a lateral displacement of the focused processing laser beam, i.e. the focus position in a plane perpendicular to the beam propagation. Alternatively or additionally, a deflection device can also be arranged in a collimated area. In this case, no displacement of the focused processing laser beam (i.e. the processing laser beam after exiting the laser processing head) is generated in the focal plane. However, an inclination of the processing laser beam emerging from the processing head can be adjusted relative to the central longitudinal axis of the laser processing head (at this point, i.e. at the exit port), for example if the focused processing laser beam is to hit the workpiece at an angle or to correct inclination errors in the optical axis.

The movable optics can include a focusing optics and/or a collimating optics, which can be moved along its optical axis in the beam path. Alternatively, the movable optics can comprise a focusing optics and/or a collimating optics, parts or elements thereof being displaceable along the optical axis in the beam path.

The laser processing head can have a control device that is set up to activate the actuator of the deflection device to adjust a tilt angle of the plate. steer. The control device can also be set up to adjust a position or a movement of the processing laser beam on the workpiece by controlling the actuator, in particular based on a linear relationship between the tilt angle and the beam offset. This can be done for the purpose of correcting the beam path and/or for the purpose of (static) alignment of the position of the processing laser beam on the workpiece and/or for generating a beam oscillation, i.e. a dynamic oscillation of the position of the processing laser beam, on the workpiece.

Brief description of the drawings

1 is a schematic side view of a laser processing head with a deflection device according to an embodiment;

Figures 2a and 2b are schematic side views of a deflection device;

Fig. 3 is a schematic representation of a tilting of a deflection device with mathematical consideration and representation of the dependency between beam offset and tilt angle;

Fig. 4a is a schematic side view of an outlet nozzle and Fig. 4b is a schematic representation of the offset in a plane (x-y) at the level of an opening of the outlet nozzle;

5-7 are each schematic side views of laser processing heads with at least one deflection device according to further embodiments;

FIG. 8a is a schematic side view of a laser processing head with a rotatable housing portion according to an embodiment, and FIG. 8b is a front view of the laser processing head shown in FIG. 8a;

9 is a schematic side view of a laser processing head with two deflection devices according to another embodiment; FIG. 10a is a schematic view of a deflection device according to another embodiment, and FIG. 10b is a schematic side view of a laser processing head according to another embodiment;

11 shows in partial figure A a schematic representation of an optical arrangement in the beam path of a laser processing head and a resulting beam position without a deflection device, and in partial figures B and C each shows a schematic representation of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in zero position and a tilt position, as well as a resulting focus position;

12 shows, in four partial images A-D, schematic representations of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in four different tilt positions and a resulting focus position;

13a and 13b each show schematic representations of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in two different tilt positions;

14 shows in partial figure A a schematic representation of an optical arrangement in the beam path of a laser processing head without a deflection device and in partial figures B and C each shows a schematic representation of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in the zero position and in one tilt position, as well as a resulting focus position;

15 shows in partial figures A and C schematic representations of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment from two different directions, and in partial figures B and D each shows schematic representations of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment from two different directions;

16a and 16b each show schematic detailed representations of an optical arrangement in the beam path of a laser processing head according to an embodiment in the zero position and in a tilt position;

Fig. 17 shows in partial figure A a schematic representation of an optical arrangement in the beam path of a laser processing head without a deflection device and in partial figures B and C each a schematic representation of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in the zero position and in one tilt position and a resulting focus position; and

18a and 18b each show schematic detailed representations of an optical arrangement in the beam path of a laser processing head with a deflection device according to an embodiment in the zero position and in a tilt position.

Detailed description of the drawings

In the following, unless otherwise noted, the same reference numerals are used for identical and identically acting elements. A redundant description of recurring features is avoided. The various embodiments and features of the figures described below can be expressly combined and are not to be understood as complete versions.

1 is a schematic representation of a laser processing head 1 according to an embodiment. 1 shows a laser processing head 1, which directs the laser light of the processing laser beam 6 from a laser source (not shown) onto a workpiece 2 in the form of a focused processing laser beam 61. For example, the laser source can be a fiber-coupled pelter laser and/or the laser processing head 1 can be a cutting head. The processing laser beam 6 is coupled from the laser source, for example by means of a fiber cable or an optical fiber 4, into an entry port 91 of the laser processing head 1.

The entry port 91 can be viewed as an interface of the laser processing head 1. The entry port 91 essentially comprises an opening through which the processing laser beam can be coupled into the laser processing head 1. The entry port 91 may be covered by a protective glass (not shown in this figure). The entry port 91 can include a coupling device 41, for example a fiber coupler, in order to couple the processing laser beam 6 from the optical fiber 4 into the laser processing head 1. The laser processing head 1 also has an exit port 7, which can also include an opening in the housing 90 of the laser processing head 1. The housing 90 may also include a nozzle in which the exit port is formed. The entry port 91, together with the exit port 7, essentially determines a central longitudinal axis 8 of the laser processing head 1. Preferably, the central longitudinal axis 8 of the laser processing head 1 corresponds to the beam path, which is defined by optical elements arranged in the laser processing head. The central longitudinal axis can also be angled. The central longitudinal axis 8 can run essentially along the optical axes of at least the refractive optical elements that are arranged in the laser processing head.

The processing laser beam 6 is focused on the workpiece 2, which, for example, melts, burns and/or evaporates as a result of the energy transfer by means of the focused processing laser beam 61. The laser processing head 1 has movable or displaceable optics 10, for example in order to focus the divergent processing laser beam 6 from a fiber end 5 of the optical fiber 4 directly onto the workpiece 2. The optics 10 may be a lens group, which may include multiple lenses, at least one of which is movable, or a single lens. The optics 10 can be moved along its optical axis (see double arrow next to the optics 10 in Figure 1) in order to set the focus position in the beam propagation direction, ie in the z-direction, to a desired value Az. Due to optomechanical tolerances, a lateral, ie xy, alignment of the focused processing laser beam 61 relative to the exit port 7 or to the center of the nozzle 7 may be necessary. In other cases A lateral movement that can superimpose a feed movement, such as an oscillating wobbling movement of the focused processing laser beam 61 on the workpiece 2, may be desired.

For this purpose, the laser processing head 1 has a deflection device 30 comprising at least one tiltable plate 30a, which has a lateral beam offset 301 transverse to the beam propagation direction (see double arrows next to the deflection device 30) or a lateral orientation, in particular a centering or displacement of the beam that is independent of the optics 10 Processing laser beam 6, enables. In this embodiment, the deflection device 30 is arranged between the entry port 91 and the (first) movable optics 10 in a divergent area DB of the beam path. In addition to the divergent area DB between entry port 91 and lens group 10, the beam path also has a convergent area KB between optics 10 and exit port 7. The laser processing head moves with respect to the workpiece 2 in a feed movement direction v.

2a and 2b are schematic representations of a deflection device 30 from two different sides. The present deflection device 30 has a plate 30a that can be tilted about at least one axis, an actuator (not shown graphically here) for tilting the plate 30a and a housing frame 31 in which the plate 30a is arranged tiltably. The actuator can also be arranged in the housing frame 31. The deflection device 30 is set up to generate a parallel offset between an entering and an exiting processing laser beam 6 by a distance dx, dy in the x or y direction. The deflection device 30 can further have a control device for controlling the actuator and/or at least one interface for controlling the actuator by an external control device, for example a control device of the laser processing head. The plate 30a can be tiltable about a first axis 30di that is parallel to the plate plane 30b and can extend in the x direction, and/or about a second axis 30d2 that is parallel to the plate plane 30b and can extend in the y direction. For tilting about different axes, the deflection device 30 can each have an actuator. The deflection device 30 shown in FIGS. 2a and 2b comprises a plate 30a, which can be tilted relative to a zero position 0 about two axes 30di, 30d2 which are perpendicular to one another and parallel to the plate plane 30b. In FIGS. 2a and 2b there is the plate plane 30b, in which both axes 30di, 30d? lie, centrally between the two plane-parallel optical surfaces of the plate 30a. The tilt angle 0 is defined here by an angle between the surface normal 30c (also called plate normal) of the plate 30a in the zero position 0 and the surface normal 30c in the tilted position. In the zero position 0 (here in the z direction), the surface normal 30c can run parallel or coaxial to the central longitudinal axis 8 of the laser processing head or to the beam path of the laser processing head. As illustrated in Fig. 2a, by rotating or tilting the plate 30a about the first axis 30di with a first tilting angle ft, a processing laser beam 6a emerging from the deflection device 30 or from the plate 30a is shifted by a distance dx in the x direction of the incident processing laser beam 6e parallel offset. The incident processing laser beam 6e, which propagates, for example, along the central longitudinal axis 8 of the laser processing head 1 in FIG the tilt angle ft on the tilted plate 30a. The emerging processing laser beam 6a has a beam propagation direction parallel to that of the incoming processing laser beam 6e. In other words, the emerging processing laser beam 6a emerges from the deflection device 30 perpendicularly, ie in the direction of the surface normal 30c in the zero position 0 or in the z direction.

Analogously in Fig. 2b, by rotating or tilting the plate 30a about the second axis 30d2 with a first tilting angle ft, a processing laser beam 6a emerging from the deflection device 30 or from the plate 30a by a distance dy in the y direction with respect to the incident processing laser beam 6e parallel offset. If the plate 30a is tilted about both axes 30di, 30d2, the respective offset dy in the y-direction and dx in the x-direction are added, so that the parallel-offset emerging processing laser beam 361 has both components of the offset. The offset between the incoming processing laser beam 6e and the exiting processing laser beam 6a therefore occurs in a plane perpendicular to the beam propagation direction. Fig. 3 shows a schematic representation of the beam path in the tilted plate 30a as well as a graphic representation of the functional relationship between the beam offset d and tilt angle or beam incidence angle 0 (bottom left) and a graphic representation of the error analysis in a linear approximation of this relationship (bottom right ). In a small angular range, in particular for tilt angles or beam incidence angles of up to 20°, an approximately linear dependence between beam offset d and tilt angle or beam incidence angle 0 can be seen. The error with a linear approximation remains tolerable even for tilt angles or beam incidence angles of up to 30°, ie less than 10%.

If one looks at the beam path through a tilted plane-parallel plate 30a, as shown in FIG. 3, where the plate 30a is in air (refractive index n = l) and itself has a refractive index n and a thickness h, the law of refraction leads

Equation [1]: sin(0)=n-sin(0') to a beam offset with a shift d

Equation [2]:

between the emerging beam 6a and the beam 6e incident at the beam incidence angle 0. The relationship (Equation 2) between the tilt angle 0 and the displacement d is not linear overall, which is generally disadvantageous for using a plate 30a to produce a precise beam offset d and requires more complicated calculation. However, the relationship can be considered almost linear for small angle values, for example in a range smaller than a critical angle value _0C . In such a case the relationship can be considered linear, as in Equation [3]:

described. The displacement d for different tilt angles 6 of two plane-parallel plates with a thickness of h = 2 mm or h = 3 mm and a refractive index of n = 1.458 is according to equations [2] and [3] in Fig. 3 bottom left for h = 2 mm (lower darker lines) or for h = 3 mm (upper lighter lines) and the absolute error or the deviation between the values of equation 3 and the values of equation 2 in percent is in Fig. 3 at the bottom right shown. The plate thickness has no influence on the relative error of the approximation of equation [2] with respect to equation [3]. The almost linear dependence of the beam offset d for small tilt angles 0 is therefore shown in the left graph. As can be seen, the dependence between beam offset d and tilt angle 0 (solid line corresponding to equation 2) hardly deviates from a linear function (dashed line corresponding to equation 3) up to approximately 15°. As already mentioned, the graph on the right shows the percentage deviation of the dependence between beam offset d and tilt angle ? described by the linear function. Up to about 20° the deviation is at values below about 5%, and up to about 30° the deviation is still at values below about 10%.

According to the invention, the tilting of the deflection device 30 is therefore specifically limited to small tilting angles of a maximum of ±30°. In particular, the tilting of the deflection device 30 is limited to tilt angles of less than approximately ±20° and preferably of less than approximately ±15°. In this way, an almost linear relationship between tilt angle? and beam offset d can be produced, which, for example, simplifies automatic adjustment of the displacement. This has the additional advantage of requiring little space and a particularly compact design.

Fig. 4a is a schematic representation of a cross section of a nozzle 70 and Fig. 4b is a schematic representation of the offset d' of the xy position 62 of the focused processing laser beam 61 with respect to the nozzle opening 71 of the nozzle 70 in the plane (xy). The offset d' of the position 62 of the focused processing laser beam 61 is indicated by the arrow in FIG. 4b and represents the possible displacement of the processing laser beam 62 to the center or to the center of the nozzle or to the central longitudinal axis 8 with the aid of the deflection device 30. The 4b shown decentralized xy position 62 of the focused processing laser beam 61 with respect to the nozzle opening 71 could be the result of different optomechanical tolerances and will be described in more detail later.

There is a difference between the lateral displacement d of the processing laser beam 6 shown in FIG. 3 and the lateral displacement of the focus position d' shown, for example, in FIG. 4b. The lateral displacement of the processing laser beam 6 shown in FIG. 3 can be influenced by increasing the size of the optical system, which will be discussed later.

5 and 6 are each schematic side representations of laser processing heads 1 according to further embodiments. The respective laser processing head 1 of FIGS. 5 and 6 differs from that of FIG. 1 in that the deflection device 30 is arranged at a different location in the beam path or two deflection devices 30 are provided. In Fig. 5, the deflection device 30, 30a is located after the (last) movable optics 10, i.e. between the movable optics 10 and the exit port 7. In Fig. 6, two deflection devices 30 are arranged along the central longitudinal axis 8, a first deflection device 30 in front of the (first) movable optics 10 and a second deflection device 30 with a second plate 30a2 after the (last) movable optics 10. The first deflection device 30 enables a beam offset 301 that is independent of the optics 10, e.g. centering, of the processing laser beam 6 in front of the Optics 10 and the second deflection device 30 enable a beam offset 301, e.g. centering, of the processing laser beam 6 after or behind the optics 10.

The lateral displacement of the focus position d' (ie the focused laser beam 61 or the laser beam after exiting the laser processing head) as a result of the beam offset d of the processing laser beam 6 through the second deflection device 30 is behind the optics 10 is essentially not influenced by the magnification of the optics 10. Therefore, the lateral displacement of the focus position d' essentially corresponds to the beam offset d between the beam entering the second deflection device and the beam emerging from the second deflection device, ie d = d'. The lateral displacement of the focus position d' as a result of the beam offset d of the processing laser beam 6 by the first deflection device 30 in front of the optics 10, however, is proportional to the magnification of the optics 10 and is therefore d = md, where m is the magnification of the optics 10.

The use of two deflection devices 30 as in FIG. 6 enables targeted correction of optical and/or mechanical tolerances of various elements at different positions.

Fig. 7 is a schematic side view of a laser processing head 1 according to another embodiment. The movable optics 10 of the laser processing head 1 of FIG. 7 is here a lens system and has two movable or displaceable lenses 13 and 14, for example a movable or displaceable converging lens 13 (movable parallel to the central longitudinal axis 8 indicated by the double arrow) and one movable or displaceable scattering lens 14 (movable parallel to the central longitudinal axis 8 indicated by the double arrow). The laser processing head or the optics 10 can also have a (preferably fixed) focusing optics 15. The movable lenses 13, 14 serve to adjust the focus position Az and the focus diameter or the magnification of the processing laser beam 6 independently of one another. A first deflection device 30 is arranged between the entry port 91 and the first displaceable lens 13. The first deflection device 30 is arranged in a divergent area DB of the beam path, that is to say in an area in which the processing laser beam 6 diverges. For example, there is a convergent region KB between the displaceable lens 13 and the second displaceable lens 14. A second deflection device is arranged between the displaceable lens 14 and the focusing optics 15. The second deflection device 30 is arranged in a convergent region KB of the beam path, that is to say in a region in which the processing laser beam 6 converges. There is a convergent area KB between the focusing optics 15 and the exit port 7. In this embodiment too, the beam offset by means of two deflection devices 30 has the advantage that the deflection of the processing laser beam can take place independently of the movable lenses and is therefore particularly precise. The first deflection device 30 in front of the first movable lens 13 is particularly suitable for compensating for or correcting tolerances of the fiber end 5 of the optical fiber 4 and/or the entry port 91 and/or the coupling device 41, since such tolerances are corrected for all magnifications. The second deflection device 30 after the second (last) movable lens 14 is particularly suitable for correcting tolerances of the exit port 7 or the nozzle 70.

As already mentioned with reference to FIG. 4b, a decentering of the processing laser beam 6 or the focused processing laser beam 61 can occur due to optomechanical tolerances. Using the embodiment of FIG. 7, the aspects that cause the decentering of the processing laser beam 6 will be explained in more detail below by way of example.

The laser processing head 1 of FIG. 7 enables different magnifications. The term “magnification” is used here for the transverse magnification of the processing laser beam 6, i.e. for an image magnification in a plane (here xy plane) perpendicular to the optical axis (here z plane). The adjustment of the diameter of the focused processing laser beam 61 or its enlargement can be viewed as a radial degree of freedom in the image plane. As a result, the degree of decentration d' of the processing laser beam 6 or the focused processing laser beam 61 depends on the magnification with respect to the tolerances of the fiber end position. This additional complexity can be conveniently handled through the use of two deflection devices 30. In particular, the first deflection devices 30 can serve to superimpose or align the diverging processing laser beam 6 with the central longitudinal axis 8 of the laser processing head 1 by means of a beam offset, so that the processing laser beam 6 falls centrally on the optics, in particular the movable optics 13, 14, and with their optical axes are superimposed. The second deflection device 30 can serve to superimpose the focused processing laser beam 61 on the central longitudinal axis 8 of the laser processing head 1 by means of a beam offset of the focused processing laser beam 61, so that the processing laser beam 6 runs centrally through the outlet nozzle 7, or to offset it in this regard. However, it should be noted that even for the laser processing head 1 of FIG. 6, a change in the focus position can lead to a significant change in the focus diameter or the magnification.

1, 5 to 7 can be a single laser processing head 1 or a single housing 90 of a laser processing head 1, which is modularly equipped with one, two or even more of the deflection devices 30 shown in FIGS. 2a and 2b can be. For this purpose, the laser processing head 1 and/or the housing 90 of the laser processing head 1 can have one or more insertion compartments, in particular after or behind the entry port 91 and/or before the exit port 7.

8a and 8b show schematic side and front views of a laser processing head 1 with a rotatable housing section 102 according to an embodiment. 8a and 8b are each representations of the same laser processing head 1 from two different perspectives. For complex 3D laser cutting applications on complicated curved surface parts, laser processing heads 1 may be required, which enable further degrees of freedom for moving the focus position or the focused processing laser beam 61. Such a laser processing head 1 is shown as an example in FIGS. 8a and 8b.

The laser processing head 1 of FIGS. 8a and 8b comprises the housing 90 with three housing sections 100, 101, 102, each of which has a central longitudinal axis 8i, 82, 83. The (entire) central longitudinal axis 8 therefore has three sections 81, 82, 83, each of which runs at an angle to one another. An entry section 101 of the housing 90 has a first central longitudinal axis 81, which runs through the entry port 91 and through a first deflection device, for example a first mirror 501. A rotation axis section or middle section 100 of the housing 90 has a second central longitudinal axis 82, which is essentially defined by the first deflection device 501, for example the first mirror, and a second deflection device 502, for example a second mirror. An exit section 102 of the housing 90 has a third central longitudinal axis 83, which is defined by the second deflection device, for example the second mirror, and the exit port 7. The exit section 102 is at the middle Section 100, for example about the second central longitudinal axis 82, rotatably attached. The respective central longitudinal axes 81, 82, 83 run in particular through the center of the elements mentioned.

A first movable or displaceable optics 16 is arranged in the entry section 101, for example a collimation lens or optics. Between the entry port 91 and the first movable optics 16 there is a divergent area DB of the beam path. A second movable or displaceable optics 15 is arranged in the exit section 102, for example a focusing lens or optics. There is a convergent region KB of the beam path between the second movable optics 15 and the exit port 7. Between the first movable optics 16 and the second movable optics 15 there is a collimated area KMB of the beam path.

With this structure, rotation of the exit portion 102 about the second central longitudinal axis 82 of the middle portion 100 and thus the focused machining laser beam 61 can be performed when an inclined surface of a workpiece 2 is to be machined. In other words, the exit section 102 of the laser processing head 1 can be rotated with respect to the entry section 101, with the middle section 100 of the housing 90 representing a rotational interface between both parts.

8b shows such a situation in which the exit section 102 of the housing 90 is pivoted about the second central longitudinal axis 82 in order to process an inclined surface. In this way, the focus height Az and the angle of the emerging processing laser beam 6 can be adjusted to the surface by pivoting the exit section 102. To describe the focus position Az, the movable coordinate system x', y', z' of the exit section 102 can be used, the z' axis of which runs parallel to the third central longitudinal axis 83.

In the laser processing head 1, the collimation lens 16 can be moved vertically essentially along the first central longitudinal axis 81 (cf. double arrow next to lens 16 in Fig. 8a) in order to be able to adjust the distance between the exit point 5 on the fiber cable 4 and the collimation lens 16. This can be helpful to compensate for tolerances or if the Laser processing head 1 is used, for example, with different laser sources and with different wavelengths in order to compensate for a possible wavelength dependence on the collimation focal length. Furthermore, the focusing lens 12 can be axially displaced along the third central longitudinal axis 83 to adjust the focus position Az'. The processing laser beam 6 is reflected twice with the aid of the mirror pair 501, 502, the angle of incidence of the processing laser beam 6 preferably being approximately 45° with each of the mirror surfaces of both mirrors of the mirror pair 501, 502.

Due to the higher degree of freedom of the focused processing laser beam 61, the laser processing head 1 has three deflection devices 30, namely a first deflection device 30 in the divergent area of the beam path or between the entry port 91 and the first optics 16, a second deflection device 30 in the collimated area of the beam path or between the first optics 16 and the first deflection device 501 and a third deflection device 30 in the convergent region of the beam path or between the second optics 15 and the exit port 7 in order to enable up to three beam offsets or axial centerings 301 to compensate for optomechanical tolerances. The use of three deflection devices 30, as indicated in FIG. 8b, enables targeted correction of mechanical tolerances. The advantages of the deflection devices 30 already mentioned also apply to this embodiment. Of course, this configuration is only an example. The laser processing head 1 can also have only one or two of the three deflection devices.

In the case of the second deflection device 30, it should be noted that it is located between the collimation optics 16 and the focusing optics 15, i.e. in the collimated area KMB. A beam offset d of the processing laser beam 6 by the second deflection device 30 therefore does not cause a shift in the focus position or the focused processing laser beam 61 in the focal plane (d - 0). However, this displacement of the processing laser beam 6 is suitable for compensating for the centering tolerances between the mechanical rotatable and the optical axes of the middle section 100.

Fig. 9 is a schematic side view of a laser processing head 1 according to another embodiment. The movable optics 10 of the laser processing head 1 of FIG. 7 is a collimation optics or lens 16 (movable parallel to the central longitudinal axis 8 indicated by the double arrow). The laser processing head can also have (preferably fixed) focusing optics 15. The movable collimation lens 16 is used to adjust the focus position Az of the processing laser beam 6. A first deflection device 30 is arranged between the entry port 91 and the first displaceable lens 16. The first deflection device 30 is arranged in a divergent area DB of the beam path, that is to say in an area in which the processing laser beam 6 diverges. A second deflection device 30 is arranged between the displaceable lens 16 and the focusing optics 15. The second deflection device 30 is arranged in a collimated area KMB of the beam path, that is to say in an area in which the processing laser beam 6 runs more or less parallel.

In this embodiment too, the beam offset by means of two deflection devices 30 has the advantage that the deflection of the processing laser beam can take place independently of the movable lenses and is therefore particularly precise. The first deflection device 30 in front of the first movable lens 13 is particularly suitable for compensating for or correcting lateral tolerances of the fiber end 5 of the optical fiber 4 and/or the entry port 91 and/or the coupling device 41. The second deflection device 30 in the collimated area is particularly suitable for compensating for or correcting tilting tolerances of the fiber end 5 of the optical fiber 4 and/or the entry port 91 and/or the coupling device 41.

The previously described embodiments show deflection devices 30, each with a plate 30, which have at least one, but in particular two tilting axes for deflection or centering of the processing laser beam 6 or the focused processing laser beam 61. The deflection device 30 with the one plate 30a can be used additionally or alternatively for oscillation or for dynamic deflection of the processing laser beam 6 or the focused processing laser beam 61.

A further embodiment of a deflection device 30' is described below, which comprises two plates 30ai and 30a2, each of which can be tilted about mutually perpendicular tilting axes. The deflection device 30 'can also be in the in Figures 1 and 5 to 9 shown embodiments of a laser processing head can be used, wherein the deflection device 30 'can replace one or more of the deflection devices 30.

10a shows a deflection device 30 'with a first plate 30ai, which is tiltable or rotatable about a first axis 30di lying in the plate plane of the first plate, and a second plate 30a2, which is about a second, in the plate plane of the Axis 30d2 lying on the second plate can be tilted or rotated. The first and second axes may be arranged perpendicular to each other to produce a two-dimensional beam offset d in the x and y directions. For the first plate 30ai, the surface normal 30c and the zero position 0 as well as the tilt angle 0x are shown. Of course, the surface normal 30c and the zero position 0 as well as the tilt angle Oy can also be drawn for the second plate 30a2, which has been omitted for reasons of clarity. Both plates 30ai, 30a2 can be tilted independently of each other. Both plates 30ai, 30a2 can preferably be designed identically, i.e. have the same thickness and/or the same refractive index.

Fig. 10b is a schematic side view of a laser processing head 1 according to a further embodiment. The laser processing head 1 has collimation optics 16, for example a lens or a lens group, for collimating or bundling the processing laser beam 6 emerging divergently from the fiber end 5 of the optical fiber 4. The laser processing head 1 also has focusing optics 15, e.g. a lens or a lens group, for focusing the processing laser beam 6 onto the workpiece 2. The collimation optics 16 can be moved along the central longitudinal axis 8 of the housing 90 (z direction of the coordinate system) in order to set the focus position Az to a desired value. The laser processing head 1 also preferably has a protective glass 21 behind the focusing optics 15 or between the focusing optics 15 and the exit port 7.

For two-dimensional deflection of the processing laser beam 6, in particular the focused processing laser beam 61 or the focus point, the laser processing head further comprises at least one deflection device 30 'with two tiltable plates. The laser processing 10b, device head 1 has three possible positions at which deflection devices 30 or 30 'can be arranged, namely a) directly behind the entry port 91 and in front of the collimation optics 16 in a divergent area, b) between the Collimation optics 16 and the focusing optics 15 in a collimated area and c) after the focusing optics 15 in front of the exit port 7 in a convergent area.

In the following, embodiments for the arrangement of the deflection devices 30 'at these positions will be considered in detail. Figs. 11-13b illustrate situation c), Figs. 14 and 16 illustrate situation a), and Figs. 17 and 18 illustrate situation b).

11 shows in partial figure A a schematic representation of an optical arrangement in a beam path of a laser processing head without a deflection device and in partial figures B and C each shows a schematic representation of an optical arrangement in a beam path of a laser processing head with a deflection device 30 'for two-dimensional deflection of the Laser beam with two plates 30ai, 30a2 in zero position or with two tilted plates 30ai, 30a2. The deflection device 30 'is arranged here after the focusing optics 15, in particular between the focusing optics 15 and the exit port 7 or the protective glass 21. In addition, the resulting intensity distributions 65 of the focused laser beam 61 in the plane of the focus position, which are the corresponding shifts or beam offsets of the focused processing laser beam 61 in a plane perpendicular to the beam propagation direction or to the central longitudinal axis 8, shown in inverse gray levels and arbitrary units.

In an exemplary embodiment, the laser processing head 1 can have a collimation lens 16 with a focal length of approximately 100 mm and a focusing lens 15 with a focal length of approximately 200 mm. With a fiber core diameter of the optical fiber 4 of approximately 100 pm, this results in a focus diameter of approximately 200 pm. The deflection device 30' has two plane-parallel plates 30ai, 30a2, for example comprising quartz glass, with a thickness of approximately 2 mm. In partial figure B, the two plates 30ai, 30a2 are in the zero position, so that no beam offset of the processing laser beam 6 is generated.

As shown in partial figure C, both plates 30ai, 30a? each can be tilted independently of each other. The first plate 30ai is tilted about a first axis 30di, which runs essentially parallel to the horizontal axis x shown in perspective, while the second plate 30a? is tilted about a second axis 30d2, which runs essentially parallel to the horizontal axis y. The values of the respective tilt angles 0x, Oy can be approximately 25° here, which, with a laser wavelength of approximately 1 pm, leads to a parallel offset of the focused processing laser beam 61 of approximately 0.3 mm in the horizontal directions x and y. In partial figure C, the focus shift d' in each of the two directions is similar to the parallel offset d of the processing laser beam 6, since in this case no magnification through optics has to be taken into account. As can be seen from the graph in FIG. 3 (bottom left), a beam offset of approximately 0.3 mm corresponds to an angle of inclination of approximately 25°.

12 shows, in four partial figures A-D, schematic representations of an optical arrangement in the beam path of a laser processing head 1 according to the embodiment of partial figures B and C of FIG. 11 in four different tilt positions, as well as the corresponding beam offsets of the focused processing laser beam 61 in a plane perpendicular to the Beam propagation direction. From this illustration, in particular from partial images C and D, the influence of the tilting of an individual plate 30ai, 30a2 becomes even clearer. In partial image A, none of the plates 30ai, 30a2 are inclined or tilted and the focus is centered in the indicated xy plane. In partial figure B, both plates 30ai, 30a2 are inclined and the focus position is shifted or deflected in both directions x and y. In partial image C, only the first plate 30ai is inclined and therefore the focus position is only shifted or deflected in the y direction. In partial image D, only the second plate 30a2 is inclined, therefore the focus position is only shifted or deflected in the x direction.

13a and 13b each show schematic representations of an optical arrangement in a beam path of a laser processing head 1 according to the embodiment of partial images B and C of FIG. 11 in two different tilt positions, namely in FIG. 13a without tilting the plates 30ai, 30a2 (zero position) and in Fig. 13b with tilting of both plates 30ai, 30a2. The deflection device 30 is arranged between the focusing lens 15 and the exit port 7 or the protective window 21. The first plate 30ai is tilted or tilted about a first axis 30di (for example parallel to the horizontal direction x) by a first tilt angle with the aid of a first actuator. Similarly, the second plate 30a2 is tilted to a second tilt angle about a second axis 30d2 (e.g., parallel to the horizontal direction y) using the same or a different actuator or actuator. A controller (not shown) is used to set the desired tilt angles using linear relationship 3, or Equation 3 of Figure 3. The tilt angles can be changed by the actuator(s) at high frequency in order to enable rapid beam deflection or high-frequency beam oscillation, for example with frequencies of approximately 100 to 500 Hz or from 1 to 5 kHz or with frequencies of more than 500 Hz , preferably more than 1 kHz, more preferably more than about 5 kHz.

Alternatively or in addition to the deflection device 30 'after the focusing lens 15, as shown in FIGS. 11 to 13, a deflection device 30' can be used in front of the collimation lens 16. Such a case is shown in parts B and C of Fig. 14.

14 shows in partial figure A a schematic representation of an optical arrangement in a beam path of a laser processing head 1 without a deflection device and in partial figures B and C each a schematic representation of an optical arrangement in a beam path of a laser processing head 1 with a deflection device 30 ', and namely in partial image B with both plates in the zero position and in partial image C with two tilted plates, as well as the corresponding displacements or beam offsets of the processing laser beam 6 or the focused processing laser beam 61 in a plane perpendicular to the direction of beam propagation.

Different tilting positions of the deflection device 30 'from FIG. 14 and FIG. 11 are compared in FIG. 15. The main differences from the previously described embodiment are discussed below. Although the two plates 30ai, 30a2 of the deflection devices 30' in the arrangement of Fig. 11 and the arrangement of Fig. 14 may have different diameters, in Fig. 15 they all have the same thickness, such as about 2 mm, and are made of the same Material, for example made of quartz glass.

Since the inclination or tilting of the plates 30ai, 30a? The beam offset d caused by the deflection device 30 ' arranged in front of the collimating optics 16 is influenced by the enlargement of the lenses of the laser processing head 1 (partial images B and D of FIG. 15), are compared to the tilt angles of the device 30 arranged after the focusing optics 15 (partial images A and C of Fig. 15) other tilt angles are necessary in order to achieve the same or a similar beam offset. The lateral magnification of the optical arrangement of the laser processing head 1 is, for example, - 2 here. Therefore, the required absolute value of the tilt angle for the plates in the deflection device 30 ' arranged in front of the collimating optics 16 is approximately 12.5 ° compared to the required absolute value of the tilt angle of 25° for the plates in the deflection device 30 'arranged after the focusing optics 15. Furthermore, the tilting directions are opposite.

The difference in the tilt angles of these two embodiments is indicated in Fig. 15. Fig. 15 shows in partial figures A and C schematic representations of an optical arrangement in a beam path of a laser processing head 1 according to the embodiment of partial figure C of FIG. 11 in two different perspectives, and in partial figures B and D schematic representations of an optical arrangement in a beam path of a Laser processing head 1 according to the embodiment of partial figure C of FIG. 14 in two different perspectives. In order to recognize this difference, both alternatives are shown one below the other in partial figures A and B or C and D of FIG.

16a and 16b each show schematic representations of an optical arrangement in a beam path of a laser processing head 1 according to the embodiment of partial figures B and C of FIG. 14. The deflection device 30 'is between the entry port 91 and the fiber end 5 of the optical fiber 4 and the collimation lens 16 arranged. The first plate 30ai is tilted about the horizontal axis 30di (for example parallel to the direction x) by a first tilt angle with the aid of a first actuator. In a similar way will the second plate 30a2 is tilted about the horizontal axis 30d2 (for example parallel to the horizontal direction y) by a second tilting angle with the aid of an actuator or the first actuator or a second actuator. A controller (not shown) can be used to set the desired tilt angles using the linear relationship or Equation 3 of FIG.

Alternatively or in addition to the arrangements of the deflection device 30′ according to FIG. 11 or Fig. 14, a deflection device 30′ can be used between the collimation lens 16 and the focusing lens 15. Such a case is shown in Fig. 16. A detail of this optical arrangement is shown in FIGS. 18a and 18b. The differences from the previously described embodiments are discussed below.

17 shows in partial figure A a schematic representation of an optical arrangement in a beam path of a laser processing head 1 without a deflection device and in partial figures B and C each shows a schematic representation of an optical arrangement of a laser processing head 1 with a deflection device 30 'with both plates in the zero position or with two tilted plates, as well as the corresponding displacements or beam offsets of the focused processing laser beam 61 in a plane perpendicular to the beam propagation direction or to the central longitudinal axis 8. The deflection device 30 'is arranged here between the collimation lens 16 and the focusing lens 17. A detail of this device is shown in Fig. 18. Since a beam offset d of the collimated processing laser beam would not lead to a lateral shift of the focus position or the focused processing laser beam 61, an optical arrangement for generating an intermediate focus is inserted between the collimation lens 16 and the focusing lens 17. The optical arrangement simplifies the integration of the deflection device 30' and creates additional space. The optical arrangement includes two lenses 17, 17' with the same focal length. The lenses 17, 17' can be identical. The processing laser beam collimated by the collimating optics 16 is first focused by the first lens 17 and then re-collimated by the second lens 17 'with the same focal length, creating an afocal magnification system with magnification -1. In this way, enough space is created for integration if necessary and two plates can be used to deflect the beam. In addition, those required for a specified shift in the focus position Tilt angle reduced. For example, if the lenses 17, 17' have a focal length of 50 mm, the beam shift magnification is 4, so that the angle of inclination required for a shift of 0.3 mm is only approximately 6.25°. Here too, a plate thickness of 2 mm was assumed for all plates.

A deflection device 30 'with two plates that can be tilted about one axis each also has the advantage that the deflection is faster and more precise than with a deflection device 30 with a plate that can be tilted about two axes. Therefore, the deflection device 30 'with two plates that can each be tilted about an axis is preferably used to generate oscillating beam movements during laser processing, so-called wobbling movements.

Reference symbols

1 laser processing head

2 workpiece

4 fiber cables or optical fiber

5 fiber ends

6 processing laser beam

6e Incident processing laser beam

6a Emerging processing laser beam

8 Central longitudinal axis of the laser processing head

81 First central longitudinal axis section

82 Second central longitudinal axis section

83 Third central longitudinal axis section

10 movable optics

13 Moving lens

14 Movable lens

15 focusing optics

16 collimation optics

17 First lens of the optics arrangement

17' Second lens of the optics arrangement

21 protective glass

30, 30' deflection device

30a plate

30ai First record

30a2 Second plate

30b plate level

30c surface normals of the plate or plate normals

30d An axis parallel to the plate plane

30di First axis parallel to the plate plane

30d2 Second axis parallel to the plate plane

31 Housing frame of the deflection device

41 coupling device

61 Focused processing laser beam 62 xy position of the focused processing laser beam

65 intensity distribution

70 nozzle

71 nozzle opening

90 laser processing head housing

91 entry port

100 middle section of the case

101 Entry section of the housing

102 exit section of the housing

301 Beam Offset

501 First Mirror

502 Second mirror

DB Divergent area d Parallel offset d _x Parallel offset in the x direction d _y Parallel offset in the y direction d' Shift of the focus position

Az focus position or height position of the focus

KB Convergent Area

KMB Collimated area

0 tilt angle

0 x First tilt angle about a first axis

0 y Second tilt angle around second axis v Direction of movement of the laser processing head above the workpiece

Claims

Patent claims

1. Deflection device (30) for a laser processing head (1) for generating a beam offset (d, dx, dy) of a processing laser beam (6), comprising: at least one plate (30a), the plate (30a) being offset by at least one to the plate plane ( 30b) parallel axis (30d) is tiltable; and an actuator for tilting the plate (30a); characterized in that a tilt angle (0) of the plate (30a) is limited to a predetermined angular range of -30° to +30°.

2. Deflection device (30) according to claim 1, wherein the plate (30a) about a first axis (30di) parallel to the plate plane (30b) with a first tilt angle (Ox) and about a second axis (30d?) parallel to the plate plane (30b). ) can be tilted with a second tilt angle (Oy), the second axis (30d?) being arranged perpendicular to the first axis (30di) and the first tilt angle (Ox) and the second tilt angle (Oy) each to an angular range of -30 ° are limited to +30°.

3. Deflection device (30) according to one of the preceding claims, wherein the at least one plate (30a) comprises: a first plate (30ai) which is about a first axis (30di) parallel to the first plate plane (30b) and has a first tilt angle (Ox ) is tiltable; and a second plate (30a?) which is tiltable about a second axis (30d2) parallel to the second plate plane (30b) at a second tilt angle (Oy); wherein the second axis (30d?) is arranged perpendicular to the first axis (30di), and wherein the first tilt angle (Ox) and the second tilt angle (Oy) are limited to an angular range of -30° to +30°.

4. Deflection device (30) according to one of the preceding claims, wherein the at least one plate (30a) has a thickness of less than or equal to 5 mm, preferably less than or equal to 3 mm.

5. Deflection device (30) according to one of the preceding claims, further comprising at least one stop device which is designed to block tilting of the plate (30a) by a tilt angle outside the predetermined angular range.

6. Laser processing head (1) for processing a workpiece (2) with a processing laser beam (6), comprising: a housing (90) with an entry port (91) for introducing the processing laser beam (6) into the laser processing head (1) and an exit port ( 7) for executing the processing beam (6) from the laser processing head (1), a beam path being defined between the entry port (91) and the exit port (7); at least one optics (10) arranged movably in the beam path; and at least one deflection device (30) arranged in the beam path according to one of the preceding claims.

7. Laser processing head (1) according to claim 6, wherein the at least one deflection device (30) is arranged between the entry port (91) and the movable optics (10) and / or between the movable optics (10) and the exit port (7).

8. Laser processing head (1) according to claim 6 or 7, wherein the at least one deflection device (30) in a divergent area (DB) of the beam path, and / or in a convergent area (KB) of the beam path, and / or in a collimated area (KMB) of the beam path is arranged.

9. Laser processing head (1) according to one of claims 6 to 8, wherein the movable optics (10) comprises a focusing optics (15) and / or a collimating optics (16) or is a part thereof.

10. Laser processing head (1) according to one of claims 6 to 9, wherein the movable optics (10) can be displaced along its optical axis in the beam path.

11. Laser processing head (1) according to one of claims 6 to 10, further comprising a control device which is set up to adjust the tilt angle (0) of the plate (30a) by controlling the actuator of the deflection device (30) and / or to the predetermined angular range to limit.

12. Laser processing head (1) according to claim 11, wherein the control device is set up to deflect the processing laser beam (6) in a one- or two-dimensional oscillating manner by controlling the actuator of the deflection device (30) and/or to align it with respect to the exit port (7).