DE102018107662A1 - Workpiece processing by means of laser radiation - Google Patents

Abstract

The invention relates to a device for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation, with a laser beam source for generating and / or a device for coupling a laser beam, a base with a propagation path for the laser beam, an arranged in the propagation path focusing optics for the Laser beam, and one of the focusing optics downstream and supported by the base working head from which the laser beam emerges, wherein the working head is provided with a protective cover.

Description

The present invention relates to a device for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation, comprising a laser beam source for generating a laser beam and / or a device for coupling a laser beam, a base with a propagation path for the laser beam, one arranged in the propagation path Focusing optics for the laser beam, and a working head downstream of the focusing optics and carried by the base, from which the laser beam emerges.

Such devices are basically known, for example DE 10 2016 103 578 A1 , The device described therein is used in particular for roughening cylinder running surfaces in cylinder bores of internal combustion engines. Here, the dipping into the cylinder bore working head is rotated about a coincident with the axis of symmetry of the cylinder bore axis of rotation and simultaneously moved in the axial direction. With the laser beam emerging obliquely from the working head obliquely to the axis of rotation, the cylinder running surface can be swept over in this way and provided with the respective desired structuring.

Devices of the type mentioned but are also used without rotating working head. Regardless of whether the working head rotates or not, the working head or the base and working head can be moved, for example, parallel to a workpiece surface or perpendicular to a surface normal of the workpiece surface. The workpiece surface can be curved or flat. In principle, it is also possible to move the workpiece relative to the stationary working head.

Structures that can be produced for roughening workpiece surfaces by means of such devices are, for example, in DE 10 2007 023 418 B4 described. These structures are so-called microstructures in the form of pocket-like depressions running obliquely at angles in the range from 20 to 80 degrees relative to the workpiece surface. The diameter of these microstructures may each be 10 to 150 microns, wherein the depth of the structures may be, for example, 20 to 300 microns.

In particular, in the production of such structures in cylinder bores, but also on differently shaped workpieces, one generally strives to minimize the processing time per cylinder bore or workpiece and at the same time produce the structures with the highest possible precision. This makes it necessary to increase the laser power as well as the speed with which the laser beam sweeps over the respective workpiece surface. When machining cylinder bores, for example, therefore, the speed of the working head must be increased. This leads to a stronger mechanical and - due to the higher laser power - and thermal stress on the components of the processing device and also increases the requirements for correct alignment of the optical components as well as the monitoring of the device and the machining process.

The object of the invention is to enable such requirements expectant workpiece machining.

The solution of this object is achieved in each case by the subject matters of the independent claims.

According to an independent aspect of the invention, in the processing apparatus, the working head is provided with a protective cover.

As a result, the working head can be protected from external influences. In particular, components arranged in an interior of the working head, in particular optical components such as, for example, a deflecting mirror for the laser beam, can be protected.

In the work area, especially at comparatively high laser powers, a strong development of heat can occur. Furthermore, laser radiation can be reflected back in the direction of the working head from the respectively processed surface of the workpiece. Furthermore, workpiece material released during laser processing, in particular in the form of hot metal splashes, can reach the working head. This can be problematical in particular if, according to an aspect of the invention described in detail elsewhere, a process gas is used to apply the respectively processed point on the workpiece or the workpiece material released in the process, as a result of which high-energy material particles flying through the working area can arise , In particular, when the process gas is ejected through a nozzle, the workpiece material melted by the laser beam is splashed around in the work area.

Against such adverse effects, the working head can be protected by the protective cover according to the invention in an advantageous manner.

Advantageous developments of this aspect of the invention are also specified in the dependent claims, the following description and the drawings.

It is preferably provided that the protective cover completely covers the working head with the exception of an exit for the laser beam. Another exception may be an exit for a process gas, if the process gas does not escape from the protective cover also by the exit for the laser beam.

The protective cover for the working head can in particular be used in an advantageous manner in addition, if there is a flow during operation in the region of the working head. Such a flow can be generated by a suction, which serves to suck the released during laser machining workpiece material. In particular, with regard to such a situation may be provided according to a development that the protective cover is formed streamlined or streamlined. In this way, in the region of the protective cover, a particularly at least approximately laminar flow can be generated which ensures a particularly effective removal of released workpiece material, in particular of material spatters expelled by means of a process gas jet.

Preferably, the protective cover is rotationally symmetrical, in particular with respect to an axis of rotation of the working head.

Furthermore, it can be provided that the protective cover tapers in the direction of a tip, in particular without edges or cracks.

The protective cover may have a smooth outer surface.

The protective effect of the protective cover can be further improved if the protective cover or a coating applied to the outside of the protective cover is made of a material which reflects heat radiation and / or the laser radiation. This gives the protective cover a further improved heat shield function.

According to a further embodiment, the working head is carried by a rotor which is rotatably mounted on the base, wherein the rotor protrudes beyond an outside of the base and carries the working head at its free end spaced from the outside, and wherein the protective cover on its Base facing the end at least approximately the same cross-sectional shape and cross-sectional size and / or the same diameter as the rotor or as a rotor surrounding, non-rotatably mounted on the base shroud of the rotor.

This makes it possible to achieve both a fluidically and optically advantageous transition between the rotor or a rotor casing and the protective cover.

It can be provided that the protective cover merges flush or with the formation of a gap or a step in the rotor or in the casing of the rotor.

According to another independent aspect of the invention it is provided that in the processing device, a gas supply is provided, which supplies a process gas to the working head.

A process gas fed to the working head can be advantageously used to influence the machining of the surface of the workpiece taking place by means of the laser beam. In particular, by exposing the workpiece surface to the process gas, the workpiece material released during laser processing can be expelled from the machined surface, in particular expelled from the surface structure generated by means of the laser beam.

As the process gas, an inert gas such as nitrogen, helium or argon can be used. It is e.g. also possible to use compressed air or oxygen as process gas.

The process gas can be supplied to the working head at a pressure which is above the usual barrier air pressures of typically about 0.5 bar. In particular, the process gas can be supplied at a pressure in the range of 1 to 15 bar.

Further preferred embodiments of this aspect of the invention are also set forth in the dependent claims, the following description and the drawings.

The working head preferably carries at least one gas outlet, via which the process gas exits the working head during operation.

It is preferably provided that the gas outlet is formed as a nozzle or comprises a nozzle. The nozzle is in particular designed to form a process gas jet. In this case, the nozzle may comprise an elongated nozzle element which protrudes from the working head or projects from the working head.

The nozzle or the nozzle element can be replaceably mounted on the working head.

Preferably, the gas outlet has an outlet opening for the process gas, whose diameter or maximum diameter in the range of 0.2 to 5.0 mm, in particular in the range of 0.5 to 2.0 mm.

In particular, in conjunction with the above-mentioned pressure ranges, sufficient energy can be imparted to the process gas jet produced thereby to expel the material resulting from the laser processing, in particular a melt resulting from the evaporation of the material, from the surface structure produced.

The outlet opening of the gas outlet is preferably circular.

In a preferred embodiment, it is provided that the laser beam also emerges from the gas outlet. Preferably, a predetermined by the gas outlet central gas outlet axis coincides with the optical axis of the exiting laser beam. In this way it is achieved that the laser beam on the one hand and the escaping gas, in particular a gas jet, aim at the respective same location of the workpiece surface. A coincidence of optical axis and gas exit axis is not mandatory. A coincidence of the laser beam and a gas jet can also be achieved if the laser beam and the gas jet emerge from the working head at different locations. Furthermore, it is not mandatory that the laser beam and a gas jet meet at a respective same location on the workpiece surface. A predetermined offset between the impact points can be deliberately predetermined.

According to a further embodiment it can be provided that the working head is provided with a protective cover, in which a gas outlet for the process gas or an opening for a gas outlet is formed. The gas outlet preferably coincides with an exit for the laser beam. The protective cover may be a cover as described above in connection with another aspect of the invention.

The protective cover can enclose an interior of the working head in such a way, in particular gas-tight, that the process gas can escape from the working head at least substantially only via the gas outlet.

The working head may have an exit window for the laser beam. Preferably, the exit window serves to separate an inner space of the working head and a process gas propagation path leading from the gas supply to the gas outlet. In particular, a gas-tight separation can take place through the exit window. Preferably, the exit window is replaceable.

According to a further embodiment of the invention it is provided that the working head is rotatably mounted on the base and rotates in operation about an axis of rotation relative to the base. In this way it can be achieved that the laser beam sweeps over the surface of the workpiece to be machined at a relatively high speed, which may be, for example, in the range of 1 to 500 meters per second.

The process gas or a process gas jet formed by a nozzle may exit the working head at an angle of 30 to 90 degrees to the axis of rotation. In particular, the exit angle is 45 degrees to 75 degrees.

Furthermore, it can be provided that the gas supply comprises a gas feed path extending in the base, wherein a rotary feedthrough for the process is formed between the gas supply path of the base and the working head or between the gas supply path of the base and a working head bearing, rotatably mounted on the base rotor is.

The rotary union may comprise a base channel formed in the base and open toward the working head or rotor, which communicates with an inlet of a gas supply path formed in the working head or in the rotor.

The rotary feedthrough may comprise a gas seal, which is formed either touching or non-contact. A contacting seal may for example be designed as O-ring, shaft, Gleitring-, piston or rod seal. As a non-contact seal, for example, a gap, sealing air or labyrinth seal can be provided.

According to a further independent aspect, the invention relates to a method for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation using a device with a laser beam source for generating a laser beam and / or a device for coupling a laser beam, a base with a propagation path for the laser beam, a focusing optics for the laser beam arranged in the propagation path, and a working head from which the laser beam emerges downstream of the focusing optics, wherein in the method of operation of the device, a process gas is applied to the surface of the workpiece to drive away the work piece material released from the machined surface of the laser processing, in particular to drive it out of a surface structure produced by means of the laser beam.

With regard to the advantages of such loading of the workpiece surface with a process gas, reference is also made to the above statements. In particular, this method uses a processing apparatus as described herein according to one of the independent aspects of the invention.

In a preferred embodiment of the method, the surface of the workpiece is subjected to a gas jet. Preferably, the gas jet exits via a gas outlet of the working head. Furthermore, it is preferred if the gas jet at least approximately aims at the same location as the laser beam emerging from the working head.

A gas outlet opening of the gas outlet is preferably guided at a distance to the surface of the workpiece which is in the range of 0.3 to 10 mm, in particular in the range of 0.5 to 5 mm.

The loading of the surface of the workpiece with the process gas can also take place if, during the machining operation, the working head or the base together with the working head on the one hand and the respective workpiece on the other hand move relative to one another. Such a relative movement constitutes a preferred embodiment of the machining method according to the invention.

It is preferably provided that the relative movement is a rotary movement. In this case, the working head may be rotatably mounted on the base and rotate in operation about an axis of rotation relative to the base and relative to the stationary workpiece. Alternatively or additionally, the workpiece can be set in rotation.

According to a further independent aspect, the invention relates to a method for machining workpieces, in particular for structuring workpiece surfaces, by means of laser radiation using a device of the type described herein, in which the working head is provided with a protective cover. In the method, a flow is generated in operation in order to suck off workpiece material released during the laser processing.

As already explained elsewhere, this combination of a protective cover for the working head with an effective flow in the region of the working head, the workpiece material released during laser machining can be reliably and effectively removed from the work area. This is the case in particular when the protective cover is streamlined or streamlined.

Structures which can be produced with the invention in workpiece surfaces can have the following dimensions: depth: 10 μm-5 mm, in particular 30-300 μm; Width: 10μm - 1mm, especially 30 - 300μm; Length: at least 10μm. If the laser is operated in continuous wave mode ("CW mode"), there will inevitably be a continuous structure of basically any length.

With the invention surface areas of workpieces (= each proportion of the surface occupied by a structure on the entire surface swept by the laser beam) can be generated, which are in the range of 5 to 100%, in particular in the range of 50 to 80%. A value of 100% is possible since overlapping structures can also be generated.

In principle, all metals are suitable as workpiece materials. In particular, workpieces made of aluminum, iron, nickel and non-ferrous alloys can be processed.

As the laser source, e.g. Semiconductor diode laser, solid-state laser, gas laser and ultrashort pulse laser can be used. In particular, high-quality lasers or single-mode lasers are used. One possible type of laser is a single-mode fiber laser. The wavelength of the laser radiation used results for each of these laser types from the specific laser used. Thus, e.g. a solid-state laser can be a fiber laser or a disk laser. A gas laser may e.g. a CO2 laser or an excimer laser.

If a pulsed laser beam is used, it is possible to work with a pulse frequency up to the MHz range. In particular, the maximum pulse frequency is at some 100 kHz, preferably below 100 kHz. The pulse duration can be in the range from 1 fs to 10 ms, in particular in the range from 1 μs to 1 ms. The laser can also be operated in continuous wave mode ("CW mode").

• 1 schematisch ein Ausführungsbeispiel einer erfindungsgemä-ßen Bearbeitungsvorrichtung,
• 2 einen vergrößerten Ausschnitt von 1,
• 3 und 4 Fotos von während des Betriebs einer erfindungsgemäßen Vorrichtung entstehenden Lichtmustern, und
• 5 bis 8 Prinzipdarstellungen von Lichtmustern, die während des Betriebs einer erfindungsgemäßen Bearbeitungsvorrichtung entstehen können.

The invention will now be described by way of example with reference to the drawings. Show it:

• 1 1 schematically an embodiment of an inventive Shen processing device,
• 2 an enlarged section of 1 .
• 3 and 4 Photos of resulting during operation of a device according to the invention light patterns, and
• 5 to 8th Schematic diagrams of light patterns that may arise during operation of a processing device according to the invention.

According to 1 and 2 The processing device according to the invention comprises a base 17 with a housing 18 , In the housing is a rotor 27 around a rotation axis 23 by means of rolling bearings 81 rotatably mounted. The rotary drive for the rotor 27 forms an electric motor, whose stator 83 is shown.

The rotor 27 protrudes from the case 18 and stands over a base of the base 17 out before. At its free end, the rotor carries 27 a working head 21 , from which during operation of the device a laser beam 15 obliquely at an angle of for example 30 ° to 90 ° to the axis of rotation 23 exit. This is in an interior 51 of the working head 21 a deflection device 25 arranged in the form of a rotating mirror, which together with the rotor 27 and thus the working head 21 around the axis of rotation 23 rotates.

The working head 21 is with a cap-like protective cover 37 provided the working head 21 - more precisely, the interior 51 and thus the components therein - with the exception of an exit for the laser beam 15 completely covers. The exit for the laser beam 15 is provided by a protective glass serving as an exit window 53 and a nozzle element 47 formed in an opening 49 the protective cap 37 sitting. Through the protective glass 53 is the interior 51 from the nozzle 47 gas-tight and thus protected against external influences.

The protective cap 37 is rotationally symmetric with respect to the axis of rotation 23 and also aerodynamically shaped, in this embodiment, on the model of a known from aviation, in front of the propeller or the engine centrally arranged spinner, which serves as a streamlined fairing. This will be discussed in more detail below.

The laser beam 15 is from an external laser beam source 11 generated and by means of a device 13 coupled into the processing device according to the invention. Alternatively, the laser beam source 11 be a part of the processing device according to the invention.

A collimation optics 29 for the laser beam 15 may have a focal length in the range of 50 to 450 mm and in particular in the range of 100 to 300 mm.

The thereby a parallel radiation course having laser beam 15 meets a semi-permeable deflection mirror 95 , The laser beam deflected in this way 15 propagates along an optical axis that coincides with the axis of rotation 23 of the rotor 27 coincides.

Within the base 17 the laser beam occurs 15 through a focusing optics 19 , which may have, for example, a focal length in the range of 150 to 600 mm and in particular in the range of 200 to 400 mm. Then the laser beam hits 15 on the in the working head 21 arranged deflection 25 due to the rotation of the working head 21 as a rotating mirror for the laser beam 15 is effective.

The focal plane of the focusing optics 19 is during operation on a surface to be machined 33 a workpiece 31 set. At the workpiece surface 33 In the application shown here is the tread of a cylinder bore 99 , In 1 is purely a workpiece example 31 with several cylinder bores 99 represented, which are to be processed one after the other.

The device according to the invention can also be used to machine differently shaped and in particular also flat workpieces.

Not shown is a special type of axial bearing of the rotor 27 , The rotor 27 is axially on one of the housing 18 formed or even on the housing 18 supported abutment, in such a way that this abutment the rotor 27 counteracts in one direction (in 1 So up), the direction of propagation of the laser beam 15 from the focusing optics 19 to the working head 21 is opposite. This ensures that the rotor 27 in case of heating, not in the direction of the working head 21 but expands in the opposite direction. A change in the distance between the not with the rotor 27 connected focusing optics 19 and the working head 21 is thus avoided. This means that the optical properties even with a thermal expansion of the rotor 27 remain unchanged.

The optical system of the processing apparatus also includes one in the optical axis of the laser beam 15 on the other side of the semitransparent mirror 95 arranged camera 85 which is a lens comprising one or more lenses 87 with an upstream optical filter 91 having.

The individual optical components of the collimation optics 29 , the focusing optics 19 as well as the lens 87 the camera 85 are each by means of an adjustment 30 . 20 respectively. 88 adjustable along the optical axis. It is possible to put the individual optical components in easy to arrange interchangeable inserts, eg in liner inserts.

The ultimate effective lens of the camera 85 is actually from the lens 87 and the focusing optics 19 formed together. In particular, in conjunction with the above-mentioned adjustability of the optical components, thereby the camera 85 be used in a variety of ways, which will be discussed in more detail below.

The base 17 is at its lower, during operation the respective workpiece 31 facing end, from which the rotor 27 projecting, provided with a multi-part functional component that serves several purposes. This functional component comprises an inner part 67 as well as an outdoor part 69 , each one cylindrical, the one from the base 17 protruding part of the rotor 27 concentric surrounding portion and a plate-shaped attachment portion 77 respectively. 79 exhibit. The shape of the attachment sections 77 . 79 corresponds to the cross section of the housing 18 the base 17 perpendicular to the axis of rotation 23 , The housing 18 is preferably cylindrical with a circular cross-section, so that the fastening portions 77 . 79 each of a circular plate with a central opening for the rotor 27 are formed. Alternatively, the housing 18 and the attachment sections 77 . 79 also have a square or rectangular cross-section.

The attachment sections 77 . 79 and the cylindrical portions of the inner part 67 and the outer part 69 are each formed integrally with each other in the illustrated embodiment. A multi-part design is alternatively possible.

The inner part 67 and the outer part 69 are at the bottom of the case 18 the base 17 thus, they do not attach and rotate during operation. The cylindrical sections, in particular an inner wall 71 of the inner part 67 and an outer sheath 39 of the outer part 69 , form a concentric jacket for the projecting portion of the rotor 27 between the bottom of the case 18 the base 17 and at the free end of the rotor 27 worn protective cap 37 ,

A purpose of this functional component 67 . 69 is to serve as a support for a work lighting, here in the form of several radiating down into the work area LEDs 35 is provided. The emitted light of the LEDs 35 can be monochromatic. Alternatively, this work lights 35 be provided with an optical filter which is permeable only for a given wavelength range. The optical filter can be embodied for example as an absorption filter, bandpass filter, dichroic filter, interference filter, edge filter or notch filter.

The work lighting 35 , optionally in conjunction with their mentioned optical filter, can be applied to the camera 85 and their optical filter 91 Be tuned to achieve an illumination of the work area, which in each case with the camera 85 implemented application is tuned.

Furthermore, the functional component serves as a fluid-cooled shield for the rotor 27 , In particular, the two cylindrical portions of the inner part form 67 and the outer part 69 one the rotor 27 surrounding cooling jacket of a fluid cooling. Above all, the fluid-cooled jacket protects the rotor 27 in front of the workpiece surface 33 reflected laser radiation. Such a "heat shield", which in the following also simply as cooling or fluid cooling of the rotor 27 is referred to, is also advantageous due to the caused by the comparatively high laser power heat development in the work area, in the illustrated embodiment, ie within the cylinder bores to be machined 99 ,

The inner wall 71 of the inner part 67 as well as the outer sheath 39 of the outer part 69 each form a cooling section of the cooling jacket and together define a cooling structure in the form of a channel system through which a cooling fluid flows 73 , this in 1 and 2 simplified as an annulus is shown. In this embodiment, the cooling structure is on the outside of the inner wall 71 formed, whereas the inside of the outer shell 39 has no cooling structures. Alternatively, they may be the fluid channel system 73 delimiting structures, such as in particular the course of the channel system determining walls or depressions, also on the inside of the outer sheath 39 be provided.

The seal is made by axially above and axially below the channel system 73 arranged O-ring seals between the inner wall 71 and the outer sheath 39 ,

The cooling fluid is preferably a liquid, in particular water. Alternatively, a gaseous cooling fluid may also be used. Preferably, the cooling fluid circulates in a circuit. With the channel system 73 and a supply and discharge channels communicating with a cooling fluid source, not shown, are not shown and run, for example, through the attachment portion 77 of the inner part. In this way, the cooling fluid can be supplied radially from the outside or discharged to the outside.

Furthermore, this serves the rotor 27 surrounding functional component 67 . 69 to that, together with the working head 21 rotating nozzle 47 to supply a process gas. The process gas is in particular an inert gas. For example, nitrogen, helium or argon can be used. It is also possible to use oxygen or compressed air as the process gas.

The use of process gases on laser processing devices is basically known. In the context of the present disclosure, a special feature is that the process gas is supplied under comparatively high pressure, ie the gas nozzle 47 is subjected to a relatively high pressure, which is higher than a typically used barrier pressure and in particular more than about 0.5 bar. In particular, according to the present disclosure, the process gas may be supplied under a pressure of more than 1 bar, and more preferably up to 15 bar and more.

The supply of the from a process gas source 42 For example, provided in the form of a gas cylinder process gas via the non-rotating functional component, the outside of the housing 18 the base 17 lying part of the rotor 27 surrounds.

In the illustrated embodiment is in the attachment section 77 of the inner part 67 a radially extending, as a gas supply 43 serving channel formed in an axially extending channel 57 passes, which forms a Basis assigned Gaszuführweg. In front of the axially lower end of the rotor 27 surrounding inner wall 71 goes the axial gas channel 57 in a ring channel 61 over, which is part of a rotary union 59 for the supplied process gas to rotate during operation rotor 27 forms. In the axial direction, this rotary feedthrough 59 by gas seals 65 sealed. These gas seals 65 can be made touching or non-contact. O-ring, shaft, sliding ring, piston or rod seals are used as contact gas seals. Alternatively, non-contact gap, sealing air or labyrinth seals can be provided.

In the event that the gas seals 65 fail, is in the case 18 the base 17 an overpressure channel 66 formed with the space between the outside of the rotor 27 and the rotor 27 facing inside of the inner wall 71 of the inner part 77 communicates. About this channel 66 can the seals 65 If necessary, overcome process gas escaping from the device without going into the heart of the base 17 to get.

In the rotor 27 is a gas supply for the gas nozzle 47 serving gas supply route 63 formed in the form of a channel, which via a radial inlet 62 permanently with the annulus 61 communicates. The gas supply route 63 of the rotor 27 goes into a gas path 55 of the working head 21 over and opens into the outlet channel of the nozzle member 47 , via which the supplied process gas to an outlet opening 48 of the nozzle element 47 stream and exit as a gas jet.

The center axis of the nozzle 47 and thus the gas jet falls with the optical axis of the previously on the mirror 25 deflected laser beam 15 together. However, this is not mandatory. In an alternative embodiment, the exiting gas jet and the exiting laser beam 15 also fall apart. The protective cap 37 may for example have a gas outlet, which is spatially separated from an outlet for the laser beam. In this case, the laser beam 15 and the gas jet is oriented to be on the workpiece surface to be machined 33 coincide, ie on the same point of the workpiece surface 33 aim.

The particular the rotating mirror 25 containing interior 51 the protective cover 37 is by that on a bracket 54 replaceable mounted protective glass 53 from the propagation path 55 of the process gas within the working head 21 separated. The process gas can not therefore be in that part of the working head 21 as well as the rotor 27 arrive, in which the optical components are located and the laser beam 15 spreads.

When in the opening 49 the protective cap 37 used nozzle element 47 it can be a replaceable component. The length of the nozzle element 47 and thus the distance of the outlet opening 48 the nozzle 47 from the other components of the working head 21 and in particular of the axis of rotation 23 can so on the dimensions of each workpiece to be machined 31 be adapted, for example, to the diameter of the inner surfaces to be machined 33 the cylinder bores 99 , In this way, a respective desired working distance between the inner surface to be machined 33 and the exit opening 48 the nozzle 47 be achieved. Depending on the particular application, this distance may be in a range of 0.3 to 20 mm and in particular in a range of 0.5 to 5 mm.

The distance of the outlet opening 48 of the nozzle element 47 from the outside of the protective cap 37 may for example be in the range of 0 to 100mm, especially in the range of 0 to 40mm. One over the outside of the protective cap 37 protruding or out of the protective cap 37 outstanding nozzle element 47 but is not mandatory. The outlet opening 48 can be in the outside of the protective cap 37 lie or be set back inside, ie the nozzle element 47 can in the cap 37 be integrated.

With a gas jet which is suitably designed in terms of strength and shape and sufficiently precisely placed, it can be achieved that the gas jet is processed during the machining of the workpiece 15 resulting melt, ie the evaporating workpiece material, is reliably expelled from the surface structure to be produced by the laser processing. As a result, surface structures can be produced with extremely high accuracy.

The working head is through the protective cap 37 and the protective glass 53 not only in front of the heat generated during the laser processing, in particular due to the workpiece surface 33 reflected laser radiation, but also protected from the resulting spatter material that are accelerated comparatively much in particular due to the use of the gas jet.

These relatively stressful working conditions in the area of the working head 21 are in particular a consequence of the comparatively high power of the laser beam 15 and the relatively high speed of the rotor 27 , These operating parameters are - as already mentioned elsewhere - required to achieve a high processing speed with high accuracy of the surface structures to be produced.

The laser processing can with a pulsed or a continuously emitted laser beam 15 respectively. The average laser power can be in the range of 200 to 5,000 watts, in particular in the range of 500 to 3,000 watts. The speed of the rotor 27 can be in the range of 300 to 20,000 rpm. The working head 21 can be moved axially at a speed of 0.1 to 30 centimeters per second. At a diameter of a cylinder bore to be machined 99 in the range of 30 to 150 mm, in particular in the range of 50 to 120 mm, machining times per cylinder of 1 to 60 seconds can be achieved with the processing device according to the invention. At a speed of the rotor 27 For example, at approximately 4500 rpm, the inner surface may be a normal bore cylinder bore 99 be provided with a surface structure in the form of a roughening within about 20 seconds.

In order to prevent that the melt resulting from the processing partly settles again on the machined surface and thus impairs the quality of the surface structure, it is already known to work with a suction. This is in 1 indicated schematically.

A suction device 93 is over suction lines 97 to the holes to be machined 99 connected, which - as in 1 at the left hole 99 indicated by the arrows - are each acted upon by their soil.

The streamlined design of the protective cover 37 of the working head 21 in the manner of a "spinner" ensures that during processing by the above-mentioned suction in the work area to the cap 37 Flow conditions arise for a reliable removal of the means of the gas nozzle 47 ensure expelled workpiece material. In particular, it can be achieved that in the area of the protective cover 37 an at least approximately laminar flow in the cylinder bore 99 effectively formed suction channel arises.

The expulsion of the material produced during processing by means of the gas jet and the reliable, by the streamlined shaping of the protective cap 37 Favored suction of the expelled material ensure extremely high machining accuracy and thus extremely high precision of each by means of the laser beam 15 fabricated surface structures.

The high machining precision is especially in view of the relatively high speed of the rotor 27 also achieved by the fact that the focusing optics 19 for the laser beam 15 not together with the rotor 27 rotates. The fixed focusing optics 19 can be easily attached and thus aligned. In particular, a fixed focusing optics 19 not exposed to centrifugal forces. However, possible misalignments of a rotating focusing optics could not be corrected practically and would result in greater inaccuracies than possible misalignments of a fixed focusing optics. In particular, eccentric Fehlauslenkungen the laser beam and an "imbalance" due to a not exactly aligned focusing optics are consequently avoided in the processing device according to the invention.

Furthermore, the non-rotating focusing optics 19 comparatively easily along the optical axis adjustable and / or interchangeable executed. As a result, the processing device can be modified quickly and easily in order, for example, to realize differently sized surface structures by adjusting the position or the focal length of the focusing optics 19 is adjusted accordingly.

With the integrated into the processing device according to the invention, the camera 85 with lens 87 and filters 91 having an observation device can firstly an initial orientation of the device and in particular of the working head 21 relative to the workpiece 31 be performed. On the other hand, it is due to the focusing optics 19 cooperating, adjustable lens 87 the camera 85 possible to adjust the focal plane of each located in the beam path optical component. In particular, the working area facing the outside of the protective glass 53 be observed during operation or in business interruptions. Furthermore, also the deflection mirror 25 be monitored by the focal plane of the camera 85 set accordingly, ie the camera 85 on the deflection mirror 85 is focused.

Furthermore, the camera can 85 be used for a running process monitoring by light patterns occurring during processing in the work area and recorded these processing patterns manually or automatically by means of image editing software. This takes place in an image processing device 86 pointing to the camera 85 connected.

Such patterns of light are in the 3 and 4 based on photos taken during a real-world editing operation as well as in the 5 . 6 . 7 and 8th each shown schematically.

As the 3 and 4 show is the camera 85 with a crosshair 90 whose center coincides with the optical axis of the processing device, whereby an exact positioning of the laser beam 15 on the surface to be processed 33 is possible.

The light pattern 89 according to 3 is regarding the crosshair 90 point-symmetrical, which can be considered a correct geometric orientation of the device. The four clubs 92 of the light pattern 89 However, not all show the same intensity. This can be considered a failure of the device.

In 4 are the two clubs 92 of the light pattern 89 different in size, which in turn can be considered as a misalignment or other disturbance of the device.

The connection between any kind of disturbance of a light pattern corresponding to a desired operating state on the one hand and a respective cause for the disturbance on the other hand can in practice be determined empirically for the respective processing device. This relationship may in particular depend on the type and the power of the laser radiation used, on the nature of the workpiece to be machined 31 , from the exit angle of the laser radiation 15 related to the axis of rotation 23 , from the speed of the working head 21 as well as the distance of the working head 21 or the deflection mirror 25 from the workpiece surface 33 ,

The disturbance can be a disturbance of the symmetry of the light pattern. In principle, however, any change in a light pattern corresponding to a desired operating state can be regarded as a fault.

The 5 . 6 and 7 show only exemplary possible symmetrical light patterns 89 that correspond to a proper target operating state of the processing device. A possible disturbance of the light pattern of 7 is in 8th shown. The symmetry of the light pattern 89 according to 8th is disturbed.

At a disturbance or change of a light pattern corresponding to a target operating state, an automatically operating, by means of the camera 85 recorded images in real-time processing image recognition software recognize a malfunction state of the processing device and then take a predetermined action. For example, the laser processing can be interrupted automatically or a corresponding signal can be output.

From the foregoing, it follows that several novel concepts are realized in the laser beam processing device according to the invention, which are already taken in each case of advantage and in particular allow in cooperation short processing times per workpiece with high processing accuracy.

LIST OF REFERENCE NUMBERS

11

laser beam source

13

launching device

15

laser beam

17

Base

18

casing

19

focusing optics

20

adjustment

21

working head

23

Rotary axis, optical axis

25

Deflection device, rotating mirror

27

rotor

29

collimating optics

30

adjustment

31

workpiece

33

Workpiece surface, inner surface

35

Work lighting, LED

37

protective cover

39

Outer shell, cooling section

41

gap

42

Process gas source

43

gas supply

45

gas outlet

47

Nozzle, nozzle element

48

outlet opening

49

opening

51

inner space

53

Exit window, protective glass

54

bracket

55

Prozessgasausbreitungsweg

57

Gas supply of the base

59

Rotary union

61

annular channel

62

inlet

63

Gas supply path of the rotor

65

gas seal

66

Overpressure channel

67

inner part

69

outer part

71

Inner wall, cooling section

73

Cooling structure, duct system

77

Attachment section of the inner part

79

Attachment section of the outer part

81

storage

83

Rotary drive, stator

85

Image capture device, camera

86

Image processing means

87

lens

88

adjustment

89

light pattern

90

crosshairs

91

filter

92

mace

93

suction

95

deflecting

97

suction

99

drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102016103578 A1 [0002]
• DE 102007023418 B4 [0004]

Claims (27)

Apparatus for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation - A laser beam source (11) for generating and / or means (13) for coupling a laser beam (15), a base (17) having a propagation path for the laser beam, - An arranged in the propagation path focusing optics (19) for the laser beam, and - One of the focusing optics downstream and supported by the base working head (21) from which the laser beam emerges, wherein the working head with a protective cover (37) is provided. Device after Claim 2 wherein the protective cover (37) completely covers the working head (21) except for an exit for the laser beam (15). Device after Claim 1 or 2 wherein the protective cover (37) is formed aerodynamically shaped or streamlined, in particular with respect to a flow generated in operation for the extraction of released in the laser machining workpiece material flow. Device according to one of the preceding claims, wherein the protective cover (37) is rotationally symmetrical, in particular with respect to an axis of rotation (23) of the working head (21). Device according to one of the preceding claims, wherein the protective cover (37) tapers in the direction of a tip, in particular without edges or cracks. Device according to one of the preceding claims, wherein the protective cover (37) has a smooth outer surface. Device according to one of the preceding claims, wherein the protective cover (37) or applied to the outside of the protective cover coating has a heat shield function and is made of a material which reflects heat radiation and / or the laser radiation. Apparatus as claimed in any one of the preceding claims, wherein the working head (21) is carried by a rotor (27) rotatably mounted on the base (17), the rotor projecting beyond an outside of the base and the working head at its end from the base Outer end spaced free end bears, and wherein the protective cover (37) at its end facing the base at least approximately the same cross-sectional shape and cross-sectional size and / or the same diameter as the rotor or as a rotor surrounding, non-rotatably mounted on the base sheath ( 39) of the rotor. Device after Claim 8 wherein the protective cover (37) merges flush or to form a gap (41) or a step in the rotor (27) or in the sheath (39) of the rotor. Apparatus for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation - A laser beam source (11) for generating and / or means (13) for coupling a laser beam (15), a base (17) having a propagation path for the laser beam, - An arranged in the propagation path focusing optics (19) for the laser beam, and - A downstream of the focusing optics and carried by the base working head (21) from which the laser beam emerges, wherein a gas supply (43) is provided, which supplies a process gas to the working head. Device after Claim 10 , wherein the working head carries at least (21) a gas outlet (45) through which the process gas exits the working head. Device after Claim 11 wherein the gas outlet (45) is formed as a nozzle (47) or comprises a nozzle which is adapted to form a process gas jet, wherein preferably the nozzle comprises an elongated nozzle member (47) which protrudes from the working head (21) or protrudes from the working head. Device after Claim 11 or 12 , wherein the gas outlet (45) has a, preferably circular, outlet opening (48) for the process gas whose diameter or maximum diameter is in the range of 0.2 to 5.0 mm, in particular in the range of 0.5 to 2.0 mm. Device according to one of Claims 11 to 13 , Wherein also the laser beam (15) emerges from the gas outlet (45), wherein preferably a gas outlet axis predetermined by the gas outlet coincides With the optical axis of the exiting laser beam. Device according to one of Claims 10 to 14 , wherein the working head (21) is provided with a protective cover (37) in which a gas outlet (45) for the process gas or an opening (49) is formed for a gas outlet, wherein preferably the gas outlet with an outlet for the laser beam (15 ) coincides. Device after Claim 15 , wherein the protective cover (37) such an inner space (51) of the working head (21), in particular gas-tight, surrounds that the process gas at least substantially only via the gas outlet (45) can emerge from the working head. Device according to one of Claims 10 to 16 wherein the working head (21) has a, in particular interchangeable, exit window (53) for the laser beam (15), wherein preferably the exit window an interior (51) of the working head and one of the gas supply (43) to the gas outlet (45) leading Prozessgasausbreitungsweg (55), in particular gas-tight, separates from one another. Device according to one of Claims 10 to 17 wherein the working head (21) is rotatably mounted on the base (17) and in operation rotates about an axis of rotation (23) relative to the base. Device according to one of Claims 10 to 18 , wherein the process gas or a process gas jet formed by a nozzle (47) exits the working head (21) at an angle of 30 ° to 90 °, in particular from 45 ° to 75 °, to the axis of rotation (23). Device according to one of Claims 10 to 19 wherein the gas supply (43) comprises a Gaszuführweg (57) extending in the base (17), wherein between the Gaszuführweg the base and the working head (21) or between the Gaszuführweg the base and a working head bearing, rotatably mounted on the base Rotor (27) is formed a rotary feedthrough (59) for the process gas. Device after Claim 20 in that the rotary leadthrough (59) comprises an annular channel (61) formed in the base (17) and open towards the working head (21) or the rotor (27), which is connected to an inlet (62) in the working head (21) or in the Rotor (27) formed Gaszuführwegs (63) communicates. Device after Claim 20 or 21 , wherein the rotary feedthrough (59) comprises a gas seal (65), either touching, in particular as O-ring, shaft, Gleitring-, piston or rod seal, or non-contact, in particular as a gap, air seal or labyrinth seal formed is. Method for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation using a device having - a laser beam source (11) for generating and / or a device (13) for coupling a laser beam (15), - a base (17) a propagation path for the laser beam, a focusing optic (19) for the laser beam arranged in the propagation path, and a working head (21) downstream of the focusing optics and carried by the base, from which the laser beam emerges, in particular using a device according to one of Claims 10 to 22 in which, during operation, a process gas is applied to the surface of the workpiece (31) in order to drive off workpiece material released during the laser machining from the machined surface, in particular to drive it out of a surface structure generated by means of the laser beam. Method according to Claim 23 , wherein the surface of the workpiece (31) with a, in particular via a gas outlet (45) of the working head (21) exiting, gas jet is applied, which preferably at least approximately to the same location as the laser beam (15) aims. Method according to Claim 24 , wherein a gas outlet opening (48) of the gas outlet (45) is guided at a distance to the surface of the workpiece (31) which is in the range of 0.3 to 20 mm, in particular in the range of 0.5 to 5 mm. Method according to Claim 25 In operation, the working head (21) or the base (17) together with the working head (21) on the one hand and the respective workpiece (31) on the other hand move relative to each other, in particular rotate relative to each other, preferably wherein the working head rotatably mounted on the base is and rotates in operation about an axis of rotation (23) relative to the base and relative to the stationary workpiece, and / or wherein the workpiece is set in rotation. Method for processing workpieces, in particular for structuring workpiece surfaces, by means of laser radiation using a device according to one of the Claims 1 to 9 wherein a flow is generated during operation to aspirate workpiece material released during laser processing.

Images