WO2005099959A1

WO2005099959A1 - Method and nozzle for treating or analyzing a work piece or a sample by way of an energetic beam

Info

Publication number: WO2005099959A1
Application number: PCT/DE2005/000651
Authority: WO
Inventors: Dirk Petring; Christian Fuhrmann; Norbert Wolf; Frank Schneider
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V.
Priority date: 2004-04-15
Filing date: 2005-04-12
Publication date: 2005-10-27
Also published as: DE102004018280A1; DE102004018280B4

Abstract

The invention relates to a method for treating or analyzing a work piece (9) or a sample by way of at least one energetic beam (3), whereby the energetic beam (3) is directed onto a spot to be treated or analyzed and a directed flow of an auxiliary medium fed via the nozzle is generated by means of the nozzle in the area of the spot to be treated or analyzed. The invention also relates to a nozzle for carrying out the method. The inventive method is characterized in that the flow of the auxiliary medium is generated to be directed away from the beam axis (4) of the energetic beam (3) and/or a surface (8) of the work piece (9) or the sample, thereby creating a suction in the area of interaction of the energetic beam (3) with the work piece (9) or the sample. The emission products produced in said area are laterally carried away from the area of interaction due to the suction effect. The inventive method and the corresponding nozzle allow for an effective near-surface removal of emission products while disturbing the interactive processes of the energetic radiation with the surface as little as possible.

Description

Process and nozzle for processing or analyzing a workpiece or a sample with an energetic beam

TECHNICAL FIELD OF APPLICATION The invention relates to a method for processing or analyzing a workpiece or a sample with at least one energetic beam, in which the energetic beam is directed at a location to be processed or analyzed and in the vicinity of the location to be processed or analyzed with at least one A directed flow of an auxiliary medium emerging from the nozzle is generated. The invention further relates to a nozzle for performing the method with a nozzle body with a through hole for the passage of the energetic

Jet and one or more outlet openings for an auxiliary medium that can be supplied via the nozzle body.

When processing or analyzing workpiece surfaces with an energetic beam, in particular from a laser, plasma or arc source, emission products, such as steam or components of a melt, emerge from the interaction zone due to the interaction of the energetic radiation with the material , This effect occurs, for example, due to temperature or pressure changes or due to phase changes in the material when cutting, cutting, removing, drilling, structuring, joining, welding, soldering or remelting. Also with other processing or analysis methods Local changes in one or more physical or chemical properties of the material can result in such undesirable emissions. On the one hand, the emissions can contaminate or damage the processing or analysis device, e.g. workpiece-related components for beam generation or shaping, optics, electrodes or nozzles, and on the other hand, they can interact with the energetic radiation above the workpiece surface in such a way that the intended effect of the radiation on the workpiece , particularly by absorption, scattering or refraction. In known methods for processing or analyzing surfaces with energetic radiation, measures are therefore taken to avoid an uncontrolled spread of the emissions caused.

PRIOR ART Numerous methods and devices for material processing with energetic radiation are known. For example, laser, plasma and arc processes are used for thermal cutting, joining and surface finishing. The machining process in these methods is often supported by supplying a gaseous or liquid auxiliary medium which is fed in via one or more nozzles to generate a directed flow in the region of the point to be machined. The liquid or gas flow is either in the direction of the interaction zone of the energetic radiation with the

Surface and / or in the direction of the beam axis of the energetic radiation to reduce the material emissions or from the interaction lead away area. The supply of the auxiliary medium thus serves on the one hand to protect the optics or electrodes of the device from contamination by the emissions, and on the other hand the interaction zone can also be shielded from the ambient air by supplying a protective gas. It is also known to influence the material properties and plasma or arc properties by suitable choice of the gas type of the auxiliary medium and the flow conditions. Finally, the transfer of compressive and / or tensile forces through the flow of the auxiliary medium can also support an intended removal of material. DE 198 02 305 AI discloses a laser welding head which has two gas outlet channels for a working gas fed to the welding point and for a protective gas for the extensive shielding of the weld seam during the welding process. The working gas strikes the welding point in the form of a centrally flowing working gas stream coaxial with the laser beam. The protective gas is also directed onto the workpiece via an annular channel with an annular outlet opening. The outlet opening is designed and arranged in such a way that an annularly closed and concavely curved (bell-shaped) protective gas flow is created to reliably shield the weld seam from the atmosphere. The publication does not address the issue of the removal of emission products. Such removal cannot be achieved by the bell-shaped closed protective gas flow in this document. Rather, this flow of inert gas incoming emission products in turn directed to the workpiece.

From S. Katayama et al. "Development of Tornado Nozzle for Reduction in Porosity during Laser Welding of Aluminum Alloy", Proc. ICALEO 2001, a method for processing a workpiece surface with an energetic beam is known in which the shielding gas is directed coaxially with the energetic radiation onto the workpiece surface and simultaneously with This swirl flow creates a negative pressure in the interaction zone for sucking off the emissions, but this does not lead them out of the radiation path.

In a technique also mentioned in this document, a swirl-free coaxial gas stream is generated, which is also directed towards the workpiece surface. Such a gas flow allows a good flow of inert gas

Shield the interaction zone from the ambient air. The flow directed at the workpiece leads to the compression of emission products and unwanted disturbances in the interaction zone, for example a weld pool. The emission products are not transported away, but are transported back in the direction of the workpiece and there lead to corresponding precipitation or buildup. From M. Kern et al. , "Optimized query concept for efficient spatter deflection and secure shielding gas supply during laser welding", Laser and Optoelectronics, Vol. 28, 1996, Edition 8, pages 62 ff, a method for surface treatment with energetic radiation is known, in which the auxiliary medium flows through transverse jets near the workpiece surface through the energetic beam. These transverse jets deflect emissions that are propagating from the workpiece surface in the direction of the components of the device and convey them out of the beam area. In order to achieve uniform processing results, however, the cross jets must also be reoriented when the processing changes direction. There is also the danger that undesirable ambient air is sucked into the interaction zone by the cross jets. The object of the present invention is to provide a method for processing or analyzing a workpiece or a sample with energetic radiation and a nozzle for carrying out the method, which allow the emission products to be removed close to the workpiece without disturbing the processing zone.

DESCRIPTION OF THE INVENTION The object is achieved with the method and the nozzle according to patent claims 1 and 11. Advantageous embodiments of the method and the nozzle are the subject of the subclaims or can be found in the following description and the exemplary embodiments.

With the proposed method for processing or analyzing a workpiece or a sample In at least one energetic jet, the energetic jet is directed in a known manner at a point on the workpiece or sample to be processed or analyzed, and a directed flow of an auxiliary medium emerging from the nozzle is generated in the vicinity of the point to be processed or analyzed with at least one nozzle , The method is characterized in that the flow of the auxiliary medium with a main flow component (= main flow direction or dominant flow direction) away from a beam axis of the energetic radiation and / or from the surface of the workpiece or sample to be processed or analyzed that a suction is generated in the area of an interaction zone of the energetic

Beam with the workpiece or the sample arises, which transports emission products accumulating there laterally out of the interaction zone. The present invention thus goes a completely different way from the known methods of the prior art, in which the main flow component of the auxiliary medium is always generated either parallel to the beam axis of the energetic radiation in the direction of the surface or directed towards this beam axis. In the present method, the main flow component directed away from the beam axis and / or surface prevents the auxiliary medium used from interacting with the interaction zone, ie the point to be processed or analyzed, or the energetic beam itself. Rather, the directional flow used in the present case creates a suction in the area of the interaction zone, which emits emission products from the side of the interaction zone. Effective zone promoted. In this way, the emission products are transported away from the effective range of the energy radiation near their point of origin without disturbing the interaction zone. Furthermore, this arrangement can be used to effectively cool the nozzle parts facing the processing point by the expanding gas or liquid flow and the rapid removal of hot emission products and to protect them from damage and buildup. In contrast to the technology of the cross jets, the flow of the auxiliary medium can also be generated rotationally symmetrically about the jet axis, so that the need for reorientation when changing the direction of processing becomes superfluous.

In an advantageous embodiment, the flow of the auxiliary medium in the present method is generated with the main flow component in a radial direction to the beam axis and / or parallel to the workpiece or sample surface. These two alternatives are the same in the cases in which the energetic radiation is directed perpendicularly onto the workpiece or the sample. However, this does not have to be the case for all applications.

Air, inert or inert gases or even reactive gases or liquids can be used as auxiliary medium in the present process. The type of medium used depends on the desired additional effect of this medium.

The one or more nozzles with which the flow is directed away from the jet axis and / or surface of the auxiliary medium is generated above the surface, depending on the desired suction effect and desired suction location at a suitable distance above the workpiece or sample surface. The volume flow of the auxiliary medium passed through the one or more nozzles can also be adjusted depending on the desired suction effect. In this way, the process can be flexibly adapted to the respective application. The nozzle proposed for carrying out the method comprises a nozzle body with a preferably central through-hole for the passage of the energetic jet and one or more outlet openings for the auxiliary medium supplied via the nozzle body. These outlet openings are arranged and formed on the nozzle body in such a way that, according to the present method, they are oriented from the central longitudinal axis of the through-hole and / or from one located on an outlet side of the nozzle and perpendicular to the longitudinal axis of the through-hole

Auxiliary plane directed main flow component of the auxiliary medium is achieved, by which a suction is created in the interaction zone of the energetic jet with a workpiece arranged in front of the nozzle, which transports emission products arising there laterally out of the interaction zone. In a special embodiment, the one or more outlet openings are arranged and designed such that the main flow direction is directed radially away from the longitudinal axis of the through hole. Of course, the nozzle body comprises one or more connections for the supply of the auxiliary medium, which via one or several channels are connected to the outlet openings.

With vectorial decomposition of the main flow component into a component perpendicular to the workpiece or sample surface and a component in the radial direction to the beam axis and / or parallel to the workpiece or sample surface, the component is in the radial direction to the beam axis and / or parallel to the workpiece or sample surface preferred embodiment of the method and the nozzle larger than the component perpendicular to the workpiece or sample surface. The one or more outlet openings for the auxiliary medium are preferably designed as slots or bores in the part of the outer nozzle wall near the workpiece, so that the flow of the auxiliary medium dominantly flows radially and forms a radial rotationally symmetrical or asymmetrical flow fan, hereinafter also called Radialj et.

When using the present nozzle, the axes of the energy beam and through hole do not always have to be coaxial or parallel. Rather, the nozzle and thus the through hole can be positioned and adjusted independently of the beam axis of the energy beam. The nozzle preferably also has a connection for supplying a further medium via the through hole. In this embodiment, the preferably central through hole provided for the passage of radiation can additionally be used as a feed channel for a gaseous or liquid, inert, inert or reactive medium, in particular for influencing emissions or processing. Furthermore, the supply of such an additional medium can compensate for the volume sucked out of the interaction zone in order to avoid suction of secondary air. The through bore is preferably provided on the side facing the workpiece with a circumferential bevel or rounding in order to avoid losses in the flow deflection of the outflowing additional medium. Other parts of the nozzle, where a flow deflection takes place, are preferably suitably rounded to avoid dead water areas. The through hole can also have further lateral openings in addition to the outlet opening close to the workpiece. The central medium supply via the through hole can be set so that secondary air is not sucked in through the additional openings. In a configuration of the through hole in which it is sealed gas-tight except for the outlet opening close to the workpiece, the central media supply via the through hole is preferably set in such a way that at least negative pressure formation in the through hole is avoided.

In the present nozzle, the outlet openings for the auxiliary medium are preferably provided with guide lips for influencing the flow direction and

Provide flow geometry. The guide lip further away from the workpiece or the sample can protrude radially further than that of the workpiece or the sample closer guide lip or vice versa. In the present nozzle, the flow contours of the guide lips can also be designed such that a flow with a convergent, divergent or composed of these properties is established in and / or outside the nozzle channel between the guide lip further away from the workpiece or sample surface and the workpiece or sample surface , for example Laval-shaped longitudinal flow section is created.

In a special embodiment of the present nozzle, its through hole is designed in such a way that it can be attached or pushed onto conventional, coaxial machining nozzles. The inner contour of the through hole is essentially adapted to the outer contour of the conventional nozzle. With this configuration, the nozzle in question can be used as an optionally mountable additional module for conventional devices for processing or analyzing surfaces.

Furthermore, the nozzle can additionally have an annular gap for the supply of a further medium, as is explained in more detail in DE 4402000 C2. In the case of a plug-on or slide-on configuration of the nozzle, as explained in connection with the previous embodiment, this annular gap can also be formed by a suitable inner contour of the present nozzle between the present and the conventional nozzle.

With the present method and the associated nozzle, several effects can be achieved simultaneously that are not or only partially possible with the previously known methods or the nozzles used in these methods. In this way, the present process and the associated nozzle enable the emission products to be removed more effectively close to where they originated. The emission products are expanded instead of compressed, so that precipitation and buildup on the workpiece surface are avoided. The suction effect promotes the degassing of welding capillaries and weld pools in the interaction zone, so that the pore formation in the material is reduced. By avoiding pressure forces in the interaction zone, which occur with direct inflow, the machining process is minimally disrupted. The method can also be operated with inexpensive auxiliary media, since an indirect flow effect is used and thus the auxiliary medium is not directly loaded on the central processing point. In contrast to known cross-jet concepts, the present radial jet concept does not lead to the extraction of process or protective gas from the interaction zone, but rather to the suction of media supplied centrally via the through-hole in the direction of the interaction zone.

With an appropriate design and choice of media, a protective effect can also be achieved in the area of the interaction zone. In the case of a flow with flow components also in the direction of the workpiece or sample surface, the area around the interaction zone can also be protected from ambient air. BRIEF DESCRIPTION OF THE DRAWINGS The present method and the associated nozzle are briefly explained again below using exemplary embodiments in conjunction with the drawings. Here show:

1 shows a first example of an embodiment of the present nozzle; and FIG. 2 shows a second example of an embodiment of the present nozzle.

WAYS OF IMPLEMENTING THE INVENTION FIG. 1 shows an example of a structure of a nozzle for carrying out the present method, only the nozzle tip essential for the invention being shown in this and the following example. The nozzle body 1 has a central through-hole 2 for the passage of the energy beam 3, for example the beam of a laser,

Plasma or arc source. The beam axis 4 of this energetic beam 3 lies in the present example on the longitudinal axis 5 of the central through hole 2. This through hole 2 serves at the same time a central media feed 6, through which process gases can be transported, for example, into the interaction zone 7 on the workpiece surface 8 of the workpiece 9. In the present example, the nozzle body 1 has a circumferential nozzle outlet slot 11 on the nozzle bottom 10 facing the workpiece 9 which a supplied auxiliary medium in the present example exits the nozzle radially to the jet axis 4 or longitudinal axis of the through-bore 5. The nozzle body has a corresponding connection 12 for the supply of this auxiliary medium, which flows in the nozzle body via a boiler space 13 to the outlet slot 11. A radial j et 14 with a dominant flow component parallel to the workpiece surface is generated by the auxiliary medium flowing radially away from the beam axis 4. Due to this flow, emission products 15 are sucked out of the interaction zone 7, as shown by the arrows. These emission products result from the interaction of the energetic beam 3 impinging on the workpiece surface 8 with the material of the workpiece surface, in particular from the rapid temperature and / or phase change in the material caused thereby. Radialj et 14 achieves a rapid removal of these emission products 15 without significantly influencing the interaction zone 7. In particular, the Radialj et 14 does not come into contact with this interaction zone 7 or the energetic beam 3. The flow guidance is additionally supported in the present example by guide lips 16 on the outlet slot 11. The volume sucked off by the suction effect is replaced by the medium supplied through the through hole 2. As can be seen in the figure, the outlet opening of the through hole is chamfered or rounded in order not to disturb the outflow of this medium.

Another example of a possible configuration of a nozzle for carrying out the present The method is shown in FIG. 2. The outlet slot 11 of the nozzle is designed via corresponding guide lips 16 such that the flow of the auxiliary medium is directed not only away from the jet axis 4 or longitudinal axis 5 of the through hole, but also away from the workpiece surface , In this embodiment too, emission products 15 are sucked out of the interaction zone 7 by this flow guide. This also applies to a possible embodiment in which the flow is generated by designing the guide lips parallel to the beam axis to the rear or inclined to the beam axis to the rear. The other components of the nozzle shown in FIG. 2 correspond to those of the nozzle of FIG. 1, so that it is no longer necessary to go into them here.

A nozzle designed according to FIG. 1 has already been successful and advantageous when welding steel materials with Nd: / YAG laser radiation

Power tested over 5 kW. About 50-100 1 / min of air were used as the auxiliary medium. The nozzle had a gap width of the nozzle slot 11 of a few tenths of a millimeter, the distance from the underside of the nozzle to the workpiece surface was a few millimeters. When welding through 10 mm thick structural steel, the welding speed was increased by 50% compared to the use of conventional cross-jet nozzles with improved seam quality. The emerging intense

Steam torch above the interaction zone could be effectively suppressed with this nozzle without disrupting the welding process. LIST OF REFERENCE NUMBERS

1 nozzle body

2 through hole 3 energetic jet

4 beam axis

5 Longitudinal axis of the through hole

6 central media feed

7 interaction zone 8 workpiece surface

9 workpiece

10 bottom of the nozzle

11 nozzle outlet slot

12 Connection for supplying the auxiliary medium 13 Boiler chamber of the nozzle

14 Radialj et

15 redirected emission products

16 guide lips

Claims

claims

1. A method for processing or analyzing a workpiece (9) or a sample with at least one energetic beam (3), in which the energetic beam (3) is directed towards a point to be processed or analyzed and in the vicinity of the point to be processed or analyzing point with at least one nozzle a directed flow of an auxiliary medium emerging from the nozzle is generated, characterized in that the flow of the auxiliary medium with a main flow component in such a way from a beam axis (4) of the energetic radiation (3) and / or from a surface (8 ) of the workpiece (9) or the sample is generated in such a way that a suction is created in the area of an interaction zone of the energetic beam (3) with the workpiece (9) or the sample, which transports emission products accumulating there laterally out of the interaction zone.

2. The method according to claim 1, characterized in that the flow of the auxiliary medium with the main flow component is generated in the radial direction to the beam axis (4) and / or in a direction parallel to the surface (8) at the point to be processed or analyzed.

3. The method according to claim 1 or 2, characterized in that the flow of the auxiliary medium is generated rotationally symmetrical to the beam axis (4).

4. The method according to any one of claims 1 to 3, characterized in that air or an inert or inert gas or gas mixture is used as the auxiliary medium.

5. The method according to any one of claims 1 to 3, characterized in that a liquid is used as the auxiliary medium.

6. The method according to any one of claims 1 to 5, characterized in that a distance of a nozzle outlet opening to the workpiece (9) or the sample and / or a volume flow of the auxiliary medium are set depending on a desired suction effect at the point to be processed or analyzed ,

7. The method according to any one of claims 1 to 6, characterized in that a further liquid or gaseous medium in the region of the point to be processed or analyzed is passed onto the workpiece (9) or the sample.

8. The method according to claim 7, characterized in that an inert or inert medium or a reactive medium which influences the processing or analysis is used as the further medium.

9. The method according to claim 7 or 8, characterized in that a volume flow of the further medium is adjusted so that suction of secondary air caused by a suction effect of the directed flow of the auxiliary medium is avoided in the direction of the point to be processed or analyzed.

10. The method according to claim 7 or 8, characterized in that a nozzle with a through hole (2) for the passage of the energetic beam (3) is used, in which the through hole (2) has a connection for the supply of the further medium and is sealed gas-tight except for an outlet opening close to the workpiece, a volume flow of the further medium through the through-hole (2) being set in such a way that vacuum formation in the through-hole (2) is at least avoided.

11. Nozzle for performing the method according to one of claims 1 to 10 with a Düsenkδrper (1) with a through hole (2) for the passage of the energetic beam (3) and or A plurality of outlet openings (11) for an auxiliary medium which can be supplied via the nozzle body (1), characterized in that the one or more outlet openings (11) are designed and arranged in such a way that the auxiliary medium with a main flow component extends from a longitudinal axis (5) of the passage bore (2) and / or from an auxiliary plane lying on an outlet side (10) of the nozzle and oriented perpendicular to the longitudinal axis (5) of the through-bore (2), emerges from the outlet openings (11) such that suction in the region of an interaction zone of the energetic beam (3) with a workpiece (9) arranged in front of the nozzle, which transports emission products accumulating there laterally out of the interaction zone.

12. Nozzle according to claim 11, characterized in that the one or more outlet openings (11) are designed and arranged such that the auxiliary medium with the main flow component in the radial direction to the longitudinal axis (5) of the through hole (2) from the outlet openings (11) emerges.

13. Nozzle according to claim 11 or 12, characterized in that the one or more outlet openings (11) are arranged radially symmetrically about the longitudinal axis (5) of the through hole (2).

14. Nozzle according to one of claims 11 to 13, characterized in that the one or more outlet openings (11) are formed in the region of an outlet side (10) of the energetic radiation (3) in an outer nozzle wall facing away from the through hole (2).

15. Nozzle according to one of claims 11 to 14, characterized in that the one or more outlet openings (11) are designed as one or more slots or bores.

16. Nozzle according to one of claims 11 to 15, characterized in that the one or more outlet openings (11) are provided with guide lips (16) for influencing the emerging flow.

17. Nozzle according to claim 16, characterized in that a processing plane closer guide lips (16) protrude further in the radial direction than from the processing plane further away guide lips (16).

18. A nozzle according to claim 16, characterized in that from a processing plane further away guide lips (16) protrude further in the radial direction than closer to the processing plane lying guide lips (16).

19. Nozzle according to one of claims 16 to 18, characterized in that the guide lips (16) have a contour through which inside and / or outside of the nozzle body (1) a flow with a divergent, convergent or from both combined longitudinal flow section arises.

20. Nozzle according to one of claims 11 to 19, characterized in that the through bore (2) has lateral inlet openings.

21. Nozzle according to one of claims 11 to 20, characterized in that the through bore (2) has a connection for the supply of a further medium.

22. Nozzle according to one of claims 11 to 19, characterized in that the through bore (2) has a connection for the supply of a further medium and is sealed gas-tight except for an outlet opening close to the workpiece.