DE102021110490A1 - Device for processing a substrate using a laser processing head - Google Patents

Abstract

The invention relates to a device for deflecting a supplied laser beam (2) with a rotatably drivable laser processing head (4) which has at least one optical element (7) for axis-parallel beam deflection of the laser beam (2) onto a processing zone of a substrate (3). In order to be able to achieve the distance (a) required for this as an offset of the exiting beam axis (13) in relation to the optical axis (6) with little structural effort, the optical element (7) has at least two wedge-shaped deflection prisms (9) which are directed in the direction the optical axis (6) are arranged one behind the other in a row arrangement. For this purpose, the deflection prisms (9) each have plane surfaces (10) arranged orthogonally to the optical axis (6) and inclined inclined surfaces (11) facing one another at a distance (s). In the deflection prisms (9), when the laser beam (2) emerges, there is a deflection due to light refraction. A flat surface processing is achieved by a superimposed translational and rotational movement of the laser processing head (4) in relation to the substrate (3).

Description

The invention relates to a device designed as a laser welding head for deflecting a laser beam, in particular for machining a substrate by means of a laser processing head of the device with at least one optical element for beam deflection, the laser beam being directed relative to the optical axis of the incident laser beam by means of the optical element along a beam axis processing zone can be deflected, with the beam axis being offset parallel to the optical axis by a distance or oriented with a small angular deviation with respect to the optical axis, and with the laser processing head being rotatably drivable about the optical axis and, in addition, the laser processing head and the substrate relative to one another in particular are designed to be movable in a translatory manner.

When processing a workpiece using a laser processing head, in particular during laser cutting or laser welding, a laser processing head with a housing is usually provided. A laser beam passing through the laser processing head to a cutting nozzle is focused by focusing optics in such a way that a workpiece can be processed. The optics for shaping the laser beam are held in the laser processing head in such a way that the optics can be adjusted relative to the housing of the laser processing head. The optics can be adjusted on the one hand in a plane perpendicular to the laser beam and on the other hand in the longitudinal direction of the laser beam.

From the EP 1 238 746 A2 a device for cutting and welding with laser radiation is known, which describes a shift of the focus position transverse to the beam axis.

From the DE 10 2013 222 834 A1 a corresponding device and a method for guiding a laser beam are known. The device for guiding the laser beam for processing a workpiece has a mirror arrangement with movable mirrors for generating an angle of incidence of the laser beam onto a focusing optic for setting a lateral offset of the laser beam on the workpiece.

From the prior art, for example EP 1 427 563 B2 or the DE 10 2008 020 575 B4 Devices for treating substrates by means of laser radiation are known with a rotating polygon mirror, by which an incident laser beam is reflected and deflected onto a plurality of converging lenses which are arranged at a distance from the substrate corresponding to their focal length.

From the DE 295 07 189 U1 a connection head for processing a workpiece by means of a laser beam is known, in which the focusing optics for the laser beam are adjustably held on a slide-in unit that can be inserted into the housing of the connection head. A manual drive, which works like a spindle drive, is provided to adjust the optics in the direction of its longitudinal axis.

From the DE 196 22 413 a cable drive is known as an adjustment drive for positioning an optical system in a laser processing head.

From the DE 43 17 384 A1 a laser processing head is known whose beam-shaping optics can be displaced in the longitudinal direction of the laser beam by a worm drive.

the DE 196 28 857 A1 relates to a connection head for processing a workpiece using a laser beam, the beam-shaping optics of which are arranged in a cassette which can be inserted into a carrier unit in the laser processing head. An electrically driven geared motor is provided to move the carrier unit in the direction of the optical axis.

the WO 2010/063 132 A1 shows a device for deflecting a laser beam for peripheral processing of a tubular substrate by means of a laser processing head, which can be driven in rotation about the optical axis by means of a rotating device. To cut off a pipe section, the laser beam is guided at least once around the entire circumference of the pipe.

In a method and a device for processing workpieces by means of laser beams according to the DE 197 45 280 A1 a laser beam is fed to a module for creating round bores with adjustable conicity. The module is designed in such a way that the laser beam is first deflected by 90° by three fixed mirrors within the module and guided to a fourth mirror, which can be moved translationally and pivoted in the propagation direction of the laser beam impinging on it.

the U.S. 4,367,017 A discloses a laser beam reflecting device for use in welding devices having a rotatable housing with at least three plane mirrors.

the DE 25 21 530 A1 relates to an apparatus and method for flame cutting by means of a laser beam. The eccentricity of a lens is adjustable, so a The laser beam can be focused in the center of the rotary movement.

Furthermore, the DE 197 29 825 C1 and the JP S59 - 54 485 A each a device and a method for the separation of tubular hollow bodies.

Furthermore, the DE 10 2009 008 650 A1 on a workpiece with a large number of micro-lubricating pockets, which are generated by means of laser pulse sequences by directing the laser beam at an angle onto the inner surface of a connecting rod eye.

The complex structure of such devices designed as a laser welding head, in particular the laser processing head, and the associated expense for the relative alignment of the optical elements has proven to be disadvantageous in the prior art. In particular when the distance between the beam axis to be directed onto the substrate and the optical axis is small, optical elements with three or more reflectors are usually required, which further increase the complexity.

Another major disadvantage of the current state of the art is that the structural arrangement of the reflectors next to one another in a common transverse plane to the optical axis leads to undesirably large dimensions, ie in particular to a large circumference of the device. The device can therefore only be used to a limited extent in cramped conditions, so that, for example, internal corners or edges on complex components cannot be reached and a remaining edge area therefore has to be reworked.

The invention is based on the object of creating a device for deflecting a laser beam which, on the one hand, requires little manufacturing effort and, on the other hand, has comparatively compact dimensions so that it can also be used in cramped spatial conditions.

The object is achieved according to the invention with a device according to the features of claim 1. The further development of the invention can be found in the dependent claims.

According to the invention, a device is therefore provided for deflecting a laser beam for machining a substrate, in particular by removing material, using a laser machining head with at least one optical element for multiple beam deflection, in which the optical element has at least two deflection prisms, in particular wedge-shaped deflection prisms, and/or wedge lenses which are configured in such a manner in are arranged in a row so that the laser beam penetrates them one after the other, with the deflection prisms or wedge lenses each having a flat surface arranged orthogonally to the optical axis and an inclined surface inclined to the flat surface, the respective inclined surfaces facing each other and being arranged at a distance and the Laser beam is deflected at the deflection prisms and / or wedge lenses in each case by refraction.

As a result, the laser beam is directed to the processing zone along a beam axis relative to the optical axis of the incident/supplied laser beam in such a way that the beam axis is parallel to the optical axis at a distance or offset or is oriented with a small angular deviation relative to the optical axis. The laser processing head with the optical element can be driven in a rotationally movable manner about the optical axis and, in addition, the laser processing head and the substrate are designed to be movable in translation relative to one another.

The invention is based on the finding that planar processing, in particular material removal from a substrate, can be carried out particularly efficiently and with a constant removal rate if the laser beam follows a circular processing zone on the substrate surface. By superimposing a further translational movement of the substrate relative to the laser processing head at an adapted speed to this movement, the processing zone reaches every sub-area of the substrate, with the orientation of the processing beam always remaining perpendicular to the substrate surface. In the superimposed movement, the laser beam follows a helical or snail-shaped processing pattern. In order to ensure that the processing beam is aligned normal to the surface of the substrate, the laser beam fed along the axis of rotation or rotation is deflected eccentrically and follows a circular path on the substrate surface around the axis of rotation, the radius of which is either fixed or adjustable. The device is primarily intended for flat processing, in particular flat removal of coatings, adhesions or layers of the substrate close to the surface.

In tests, it has already been found to be advantageous that the circular movement compared to a linear deflection of the laser beam leads to a significantly reduced temperature rise in the substrate, so that in particular heating to a temperature above half a critical temperature, for example the melting temperature of the substrate, can be reliably avoided.

According to the invention, the deflection of the laser radiation is not achieved by reflectors and not by total reflection, but by refraction of light or dispersion at a plurality of deflection prisms or wedge lenses. As a result, a design can be realized in which the prisms are arranged one behind the other in the direction of the optical axis, that is to say in particular coaxially or concentrically. As a result, there is less structural effort for the laser processing head, which can be designed, for example, as an at least partially tubular hollow body in which the deflection prisms or wedge lenses are arranged at a small distance from one another. Both clamping and form-fitting fixing means are suitable for fixing. A common fixation, for example by a pretension acting parallel to the optical axis, enables a quick and easy assembly of several deflection prisms or wedge lenses at the same time, the spacing of which can be adjusted, if necessary, by means of, in particular, interchangeable spacers.

The external dimensions of the laser processing head are comparatively compact due to the arrangement of the deflection prisms or wedge lenses arranged axially one behind the other and in the cross-sectional plane to the optical axis are only slightly larger than the diameter of the deflection prisms or wedge lenses. If the device has an integrated drive for the rotational movement of the laser processing head about the optical axis, this can be arranged in an axial extension to the laser processing head in order to keep the external dimensions as small as possible.

According to an advantageous embodiment, the beam axis is deflected by the first deflection prism and/or the first wedge lens at an acute angle of less than 90° relative to the optical axis and the deflected laser beam is also directed at an acute angle of less than 90° onto the inclined surface of the adjacent deflection prism or the adjacent wedge lens, the desired parallel offset of the beam axis deflected onto the substrate can be set with high accuracy.

The deflection prism is particularly preferably designed as a dispersion prism, for example as an isosceles or equilateral dispersion prism, at which there is no total reflection of the laser beam.

Since when the laser beam passes through the deflection prisms and/or the wedge lenses, the laser light is deflected from its original direction of propagation by refraction on the two non-parallel surfaces of the respective deflection prism or wedge lens, and the strength of the deflection depends on the wavelength spectral resolution, which depends, among other things, on the dispersion strength. As a result, the energy input per unit area in the deflection prism or the wedge lens and the heating are reduced at the same time, so that the cost of cooling the laser processing head is low.

Furthermore, the deflection prisms or wedge lenses can be arranged in a common receptacle which has cooling channels and/or cooling ribs through which flow can take place, in particular helically or helically designed, in order to ensure an effective cooling effect, especially at high laser powers. Ambient air supplied, for example, can be considered as the coolant, with liquid coolant also being able to be used. There is no need for direct wetting of the deflection prisms or wedge lenses by the coolant if the mount is made of a material with good thermal conductivity.

The distance between the deflection prisms and/or wedge lenses can be fixed unchangeably by a spacer, in particular a ring-shaped spacer, when the device is in use, with the spacer preferably being fixed to the optical element in an exchangeable manner. According to one embodiment of the invention, the distance between the deflection prisms and/or wedge lenses can also be adjusted, for example, during processing, in order in particular to be able to adapt the processing area to different substrate sizes. For this purpose, sensory monitoring of the processing surface can also be provided in addition, in order to be able to adjust the distance by means of a control unit. If necessary, this could also be varied cyclically during a full rotation of the processing head around the optical axis. For example, a worm-shaped machining with a continuously or discontinuously changed radius can also be carried out in this way, with the additional relative translational movement of the machining head and the substrate being correspondingly adapted or omitted according to one variant.

In another, likewise particularly practical modification of the invention, the deflection prisms or wedge lenses are arranged such that they can rotate relative to one another about the optical axis, so that by changing the relative rotational angle position of adjacent deflection prisms or wedge lenses at the same time, the distance between the facing inclined surfaces of the deflection prisms or wedge lenses is changed. The relative rotation about an axis parallel to the optical axis maintains the inclination of the inclined surfaces of the deflection prisms or wedge lenses with respect to a cross-sectional plane to the optical axis, while the inclined surfaces are brought closer to one another. This relative rotational movement can also be initiated from the outside without any problems or can also be carried out during the processing of the substrate.

At least one deflection prism or wedge lens can be positioned at different axial distances relative to the optical axis.

The position of the movable deflection prism or the movable wedge lens can be adjusted manually, for example by means of a threaded spindle. In addition, an in particular electromotive adjusting means can be used, which according to a further development can also be confirmed during the processing of the substrate in order to change the distance or the parallel offset of the beam axis from the optical axis during the laser processing, in particular due to sensory recorded measured values.

It is particularly advantageous if at least one deflection prism or wedge lens can be moved by means of a sliding guide, with the adjustment movement being able to be initiated manually or electrically. The adjustment movement of the deflection prism or the wedge lens is not limited to a single degree of freedom. Rather, it has been found that an adjustable angle of inclination can be useful for adaptation to, for example, curved or angled areas of the surface of the substrate.

Another, likewise particularly advantageous embodiment of the invention is also achieved in that the device has a focusing element for focusing the laser radiation on the processing zone on the surface of the substrate, the size of the focal spot on the surface at the same time determining the intensity of the thermal energy introduced of the adjustable focus can be determined and adjusted.

Since a very small distance between the beam axis on the substrate and the optical axis can be set according to the invention, on the one hand almost any gap width can be set or bridged for welding or soldering tasks, which expands the possible uses of laser welding or soldering, which is known per se, to a large number of Applications can be expanded, which were previously excluded from this due to large gaps. On the other hand, thin sheet metal can also be processed without any problems because the local thermal energy input is low due to the rotating movement.

• 1 eine perspektivische Darstellung einer erfindungsgemäßen Vorrichtung mit einem Laserbearbeitungskopfzur Ablenkung eines Laserstrahls;
• 2 eine vergrößerte Darstellung des in der 1 gezeigten Laserbearbeitungskopfs ;
• 3 eine geschnittene Seitenansicht des Laserbearbeitungskopfs mit zwei Keilprismen;
• 4 eine Seitenansicht des Laserbearbeitungskopfs mit einer andeutungsweise dargestellten Aufnahme für die Keilprismen;
• 5 eine Seitenansicht der in 4 gezeigten Aufnahme;
• 6 eine perspektivische Darstellung der in 4 gezeigten Aufnahme;
• 7 eine perspektivische Darstellung eines Abstandshalters für die Keilprismen;
• 8 eine Vorderansicht des in den 3 und 4 gezeigten Laserbearbeitungskopfs.

The invention permits various embodiments. To further clarify its basic principle, one of them is shown in the drawing and is described below. This shows in

• 1 a perspective view of a device according to the invention with a laser processing head for deflecting a laser beam;
• 2 an enlarged view of the in the 1 shown laser processing head;
• 3 a sectional side view of the laser processing head with two wedge prisms;
• 4 a side view of the laser processing head with a receptacle for the wedge prisms shown in outline;
• 5 a side view of the in 4 shown recording;
• 6 a perspective view of the 4 shown recording;
• 7 a perspective view of a spacer for the wedge prisms;
• 8th a front view of in the 3 and 4 shown laser processing head.

A device 1 according to the invention, designed as a laser welding head, is described below with reference to FIG 1 until 8th explained in more detail. The device 1 is used to deflect a laser beam 2 onto a substrate 3, which is only shown in outline, and in particular enables linear processing, in particular a planar removal of material on the surface of the substrate 3. For this purpose, the laser beam 2 follows a circular processing line on the surface of the substrate 3, which a further translational relative movement of the substrate 3 relative to the device 1, represented by a double arrow 5, is superimposed at an adapted speed, with the orientation of the laser beam 2 always being maintained perpendicular to the substrate surface. As a result, the superimposed movement results in a helical or snail-shaped processing pattern on the surface of the substrate 3.

In order to generate this desired processing pattern with comparatively little effort, the device 1 has a laser processing head 4 with an optical element 7 that the laser beam 2 can be deflected relative to an optical axis 6 of the incident laser beam 2 along a beam axis 13 onto the processing zone. This beam axis 13 is spaced parallel to the optical axis 6 by a distance a, a'. Because the laser processing head 4 is driven in a rotationally movable manner about the optical axis 6 by means of a drive unit 8, a circular processing line with a radius corresponding to the distance a, a′ is produced on the substrate.

In order to achieve this distance a as an offset of the exiting beam axis 13 in relation to the optical axis 6 with little structural effort and at the same time compact dimensions of the laser processing head 4, the optical element 7 has at least two wedge-shaped deflection prisms 9, which are arranged one behind the other in the direction of the optical axis 6 in are arranged in a row. For this purpose, the deflection prisms 9 each have a flat surface 10 arranged orthogonally to the optical axis 6 and an inclined, non-parallel inclined surface 11, the inclined surfaces 11 of the deflection prisms 9 facing each other and the flat surface 10 being arranged facing away from one another. In principle, the inclined surfaces 11 do not lie directly against one another, but are arranged at a distance s, s′, which can be between 1/10 mm and several centimeters.

The deflection prisms 9 cause dispersion when the laser beam 2 exits, so that the deflection of the laser beam 2 is based on refraction. There is therefore no total reflection at the deflection prisms 9, which therefore in particular do not serve as reflectors.
Rather, the laser beam 2 penetrates a focusing element 20 and the deflection prisms 9 one after the other, deflection occurring as a result of light refraction on the two inclined surfaces 11 . According to the deflection angle α resulting from the wedge angle, the laser beam 2 emerges from the inclined surface 11 of the first deflection prism 9 at an acute angle α to the optical axis 6 and at a likewise acute angle β into the inclined surface 11 of the second deflection prism, which is identical here 9, causing another distraction. The laser beam 2 thus emerges from the planar surface 10 of the second deflection prism 9 along the beam axis 13 parallel to the optical axis 6 .

By a translational movement of the lower deflection prism 9 in the direction of the arrow 12 parallel to the optical axis 6, the distance s, s' as a gap between the deflection prisms 9 is changed as required or calibrated to set predetermined values. A greater radial beam deflection is achieved by an increased distance s′ in the gap, so that the resulting beam axis 13 has a greater parallel offset with a distance a′ relative to the optical axis 6 .

According to a variant not shown, this setting of the deflection prisms 9 can also be changed during operation, the deflection prisms 9 being arranged with a single degree of freedom such that the relative angular position with respect to the optical axis 6 remains unchanged during use.

As in particular in the 3 until 6 the deflection prisms 9 are arranged in a basic hollow-cylindrical receptacle 14, the receptacle 14 having circumferentially flowable, in particular helical, cooling channels 16 delimited by cooling ribs 15, through which a coolant, in particular ambient air, can flow when in use.

Furthermore, the receptacle 14 has a plurality of slit-shaped recesses 17, in which an annular spacer 18, which is inserted between the deflection prisms 9 and determines the distance s, can be inserted with peripheral projections 19 and is thereby fixed in a rotationally fixed manner. The ring-shaped spacer 18 is arranged on the receptacle 14 so that it can be exchanged, so that the parallel offset of the decoupled laser beam 2 along the beam axis 13 can be varied in a simple manner by exchanging the spacer 18 .

The outer dimensions of the laser processing head 4 are comparatively compact due to the axial arrangement of the deflection prisms 9 one behind the other and in the cross-sectional plane to the optical axis 6 are only slightly larger than the diameter of the deflection prisms 9.

reference list

1

contraption

2

laser beam

3

substrate

4

laser processing head

5

double arrow

6

optical axis

7

optical element

8th

drive unit

9

deflection prism

10

flat surface

11

bevel

12

arrow direction

13

beam axis

14

recording

15

cooling fins

16

cooling channels

17

recess

18

spacers

19

protrusions

20

focusing element

a, a'

Distance

s, s'

Distance

a

angle

β

angle

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1238746 A2 [0003]
• DE 102013222834 A1 [0004]
• EP 1427563 B2 [0005]
• DE 102008020575 B4 [0005]
• DE 29507189 U1 [0006]
• DE 19622413 [0007]
• DE 4317384 A1 [0008]
• DE 19628857 A1 [0009]
• WO 2010/063132 A1 [0010]
• DE 19745280 A1 [0011]
• US4367017A [0012]
• DE 2521530 A1 [0013]
• DE 19729825 C1 [0014]
• JP59054485A [0014]
• DE 102009008650 A1 [0015]

Claims (14)

A device (1), designed as a laser welding head, for deflecting a laser beam (2) for machining a substrate (3), in particular by removing material, using a laser machining head (4) with at least one optical element (7) for beam deflection, the laser beam (2) opposite the optical Axis (6) of the incident laser beam (2) can be deflected by means of the optical element (7) along a beam axis (13) onto the substrate (3), the beam axis (13) being at a distance (a , a') is spaced parallel or oriented with a small angular deviation relative to the optical axis (6), and wherein the laser processing head (4) can be driven to rotate about the optical axis (6) and, in addition, the laser processing head (4) and the substrate (3 ) are designed to be movable relative to one another, in particular translationally, characterized in that the optical element (7) has at least two deflection prisms (9), in particular keif shaped deflection prisms and/or wedge lenses, the deflection prisms (9) and/or wedge lenses being arranged in a row in such a way that the laser beam (2) penetrates the deflection prisms (9) and/or wedge lenses one after the other, and that the deflection prisms (9 ) and/or wedge lenses each have a flat surface (10) arranged orthogonally to the optical axis (6) and an inclined surface (11) inclined to the flat surface (10), the inclined surfaces (11) of adjacent deflection prisms (9) and/or wedge lenses facing each other and are arranged at a distance (s), and that the laser beam (2) can be deflected at the deflection prisms (9) and/or wedge lenses by light refraction. Device (1) after claim 1 , characterized in that the laser beam (2) is deflected by the first deflection prism (9) and/or the first wedge lens at an acute angle (a) relative to the optical axis (6), and that the deflected laser beam (2) is deflected with a acute angle (β) meets the inclined surface (11) of the adjacent deflection prism (9) and/or the adjacent wedge lens. Device (1) after claim 1 or 2 , characterized in that the optical element (7) has at least two relative to each other movable deflection prisms (9) and / or wedge lenses. Device (1) according to at least one of the preceding claims, characterized in that deflection prisms (9) and/or wedge lenses can be positioned at different axial distances (s, s') from one another in relation to the optical axis (6). Device (1) according to at least one of the preceding claims, characterized in that at least one deflection prism (9) and/or at least one wedge lens is movably arranged on the laser processing head (4) by means of a sliding guide. Device (1) according to at least one of the preceding claims, characterized in that the deflection prisms (9) and/or wedge lenses are arranged at an adjustable distance (s) from one another. Device (1) according to at least one of the preceding claims, characterized in that the distance (s) between the inclined surfaces (11) of the deflection prisms (9) and/or wedge lenses is determined by a spacer (18), in particular ring-shaped, which in particular can be exchanged on the optical element (7) is fixed. Device (1) according to at least one of the preceding claims, characterized in that the deflection prisms (9) and/or wedge lenses are arranged to be rotatable relative to one another about the optical axis (6), and that by changing the relative angular position of adjacent deflection prisms (9) and/or wedge lenses, the distance (s) between the facing inclined surfaces (11) of the deflection prisms (9) and/or wedge lenses is variable. Device (1) according to at least one of the preceding claims, characterized in that the deflection prisms (9) and/or the wedge lenses are arranged in a receptacle (14), the receptacle (14) being designed, in particular helically or helically, through which a coolant can flow Has cooling channels (16) and / or cooling fins (15). Device (1) according to at least one of the preceding claims, characterized in that the distance (s) can be continuously changed during operation. Device (1) according to at least one of the preceding claims, characterized in that the distance (s) can be adjusted during operation independently of the angular position relative to the optical axis (6) of the deflection prisms (9) and/or wedge lenses. Device (1) according to at least one of the preceding claims, characterized in that the deflection prisms (9) and/or wedge lenses are arranged in the receptacle (14) of the optical element (7) parallel to the optical axis (6) and can be moved in translation relative to one another . Device (1) according to at least one of the preceding claims, characterized in that the device (1) has a focusing element (20) for focusing the laser beam (2) onto the processing zone of the substrate (3). Optical element (7) for use in a device (1) according to at least one of the preceding claims, characterized in that the optical element (7) has at least two in particular wedge-shaped deflection prisms (9) and/or wedge lenses, the deflection prisms (9) and/or wedge lenses are arranged in a row in such a way that the laser beam (2) successively penetrates the deflection prisms (9) and/or wedge lenses, and that the deflection prisms (9) and/or wedge lenses each have a direction orthogonal to the optical axis (6) arranged flat surface (10) and an inclined surface (11) inclined to the flat surface (10), wherein the inclined surfaces (11), the deflection prisms (9) and/or wedge lenses face each other and are arranged at a distance (s) so that the Laser beam (2) can be deflected by light refraction at the deflection prisms (9) and/or wedge lenses.

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