Device for a laser-hybrid welding process

The invention describes an apparatus, in particular a laser hybrid welding head (1) for a laser hybrid welding process, in which a laser (4) or laser optics or an optical focussing unit and elements of a welding torch (5) for an arc welding process and/or a feed device for a welding wire as well as a device for generating a cross jet (8) connected by at least an incoming line (9) and an outgoing line (10) to a compressed air supply system, are mounted on at least one mounting element (2). The incoming line (9) and the outgoing line (10) carrying compressed air for the cross jet (8) are disposed between the two components, in particular the laser (4) and laser optics or the optical focussing unit and the elements of the welding torch (5) or feed device for the welding wire (21).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an apparatus, in particular a laser hybrid welding head, for a laser hybrid welding process, as well as a cross jet guide device for a laser hybrid welding process, of the type defined in claims1and14.

2. Description of the Prior Art

Apparatus is already known, in particular laser hybrid welding heads, for a laser hybrid welding process, in which a laser and laser optics or an optical focussing unit and a welding torch are disposed on a mounting plate. A cross jet guide device co-operates with the laser and the optical focussing unit in order to form a cross jet, the cross jet guide device being connected to a compressed air supply system by an incoming line and an outgoing line. As a result of the so-called cross jet, the optical system of the laser or the laser optics or the optical focussing unit are shielded from any weld splatter generated during welding processes. The incoming line and the outgoing line are provided on either side of the laser and the laser optics or the optical focussing unit. When using apparatus of this type during a welding process, the surface of the workpiece is heated by the premature laser and laser optics or the optical focussing unit or melting may be initiated below the surface of the workpiece due to focussing on the focal point or burning to a certain depth due to the laser beam, so that during the subsequent arc welding process the burned depth becomes even greater resulting in a welding bead due to the delivery of a welding wire or an additional material.

The disadvantage of this situation is that a considerable amount of space is needed to run the incoming and outgoing line on either side, which significantly increases the size of a laser hybrid welding head of this type.

Devices for generating a cross jet are also known, in which an outlet element and an inlet element for compressed air are provided on either side of the laser and laser optics or optical focussing unit, enabling a cross jet, in other words an air flow, to be generated between the outlet element and the inlet element to pick up any loose metal debris.

The disadvantage of this system is that the cross jet produced by this structure is necessarily large in terms of surface area, resulting in a very high vacuum pressure in the region of the cross jet, making it necessary to dispose the latter at a large distance from a welding process when operating with a shielding gas atmosphere to prevent it from being sucked away.

Documents U.S. Pat. No. 5,981,901 A, U.S. Pat. No. 5,814,786 A and EP 0 618 037 A describe methods and devices for laser welding, in which a cross jet guide device is used to protect against welding splatter. The cross jet guide device is provided in the form of an elongate housing and a compressed air supply system is disposed on one side of the housing to deliver compressed air to create a cross jet in the interior, which then leaves the housing from the oppositely lying side of the housing. The housing also has an end-to-end orifice for a laser beam, which extends through the orifice.

The disadvantage of this approach is that a cross jet guide device of this design requires a large amount of space and is of large structural dimensions because the incoming and outgoing lines for the compressed air are arranged on either side of the housing. Consequently, a cross jet guide device of this type can only be used for a pure laser welding process.

Patent specification WO 00/24543 A also discloses a laser hybrid welding head, the laser of which is disposed at the centre. On either side of the laser a respective welding torch is mounted by means of a common mounting rail and can be displaced by means of the mounting rail.

This disadvantage of this structure is that it does not permit the use of a cross jet guide device and the laser optics become soiled by welding debris after a short welding time, which sharply reduces the power of the laser.

SUMMARY OF THE INVENTION

The underlying objective of the invention is to propose an apparatus, in particular a laser hybrid welding head for a laser hybrid welding process, and a cross jet guide system, whereby the component size is compact and the structure of the laser hybrid welding head and the cross jet guide device is simple.

This objective is achieved by the invention due to the fact that the incoming line and the out-going line for the compressed air for the cross jet are disposed between two of the components, in particular the laser and the laser optics or the optical focussing unit, and the elements of the welding torch or the feed apparatus for the welding wire. The advantage obtained by the special design of the laser hybrid welding head is that there are no lines at all in the area around the individual components and no lines running into the region around the welding process because they are all connected to the components at the oppositely lying end. This avoids the laser hybrid welding head from being left hanging from an object because there are no lines standing out around the components. The fact that the laser hybrid welding head can be used in mirror image without changing the robot, in particular its programmed path, is a major advantage because the laser hybrid welding head is designed to be symmetrically attached to the robot, in particular to the manipulator of the robot arm, and there is no need to make allowance for any protruding lines or parts, whilst the special design of the laser hybrid welding head means that it can also be used for areas that are not readily accessible.

The objective of the invention is also achieved due to the fact that the housing of the cross jet guide device has an end-to-end orifice for a laser beam extending through the orifice, and an outlet passage and an oppositely lying inlet passage for the compressed air, in particular for the cross jet or the cross jet flow, is provided in the end faces of the orifice The advantage of this is that by using this type of cross jet with a cross jet guide device, a closed system is created inside the housing and the cross jet flow occurs within the orifice only so that there are no or only slight air flow outside of this orifice. This enables the distance left between the cross jet or cross jet guide device and the welding process, in particular the arc welding process, to be kept very short, significantly reducing the construction size of the laser hybrid welding head, which considerably improves handling of the laser hybrid welding head.

The objective is also achieved by the invention due to the fact that the torch or the welding torch is made up of several individual modules and at least one module, in particular the torch body, can be changed in order to run a whole range of different joining processes, in particular a welding process or a soldering process. The advantage of this is that the laser hybrid welding process can be adapted to operate a whole range of different joining process with little effort. Another major advantage resides in the fact that, because of the special design of the laser hybrid welding head, the process of changing the torch body in readiness for a different welding process can be automated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Firstly, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc,. relate to the drawing specifically being described and can be transposed in terms of meaning to a new position when another position is being described. Individual features or combinations of features from the different embodiments illustrated and described may be construed as independent inventive solutions or solutions proposed by the invention in their own right.

FIGS. 1to5illustrate an example of one embodiment of an apparatus, in particular a laser hybrid welding head1, and a specially designed mounting element2for mounting the individual components of the laser hybrid welding head1.

Standard, commercially available elements and units known from the prior art are employed and used in a special combination with one another in the laser hybrid welding head1proposed by the invention. Accordingly, a laser4and a laser optical system or an optical focussing unit and elements of a welding torch5for an arc welding process6, schematically indicated, or a feed device for a welding wire or an electrode, as well as a cross jet guide device7for forming a cross jet8, connected to a compressed air supply system—not illustrated—by at least one incoming line9and one outgoing line10, are mounted on the mounting element2, which is connected to a robot, in particular a robot arm3, as schematically indicated.

In the laser hybrid welding head1proposed by the invention, the mounting element2has a section11corresponding to the diagram given inFIG. 2, with mounting grooves12for the components of the laser hybrid welding head1. The section11is designed with an end-to-end passage13through the centre, which preferably constitutes or is connected to the outgoing line10, and, parallel with this passage13, two other passages14,15, which preferably constitute or are connected to the incoming lines9. As a result, the incoming line9and the outgoing line10for the compressed air delivered for the cross jet8are disposed between the two components, in particular the laser4and the laser optics or the optical focussing unit and the elements of the welding torch5, as schematically indicated, and, in the particular embodiment illustrated as an example inFIGS. 1 and 2, the incoming line9and the outgoing line10are integrated in the mounting element2, in particular in the section11, so that the compressed air for the cross jet8is delivered and discharged on one side of the cross jet guide device7. In the embodiment described below and illustrated as an example inFIG. 6, however, the incoming line9and the outgoing line10are no longer integrated in the mounting element2or the section11but extend parallel with the section11, so that, again, they are disposed between the two components, in particular the laser4and the welding torch5. In this example—illustrated in FIG.6—the section11also has no internally lying passages13to15.

To enable the section11to be secured to a manipulator16of a robot, in particular a robot arm3, in the most effective way possible, the section11is connected to the manipulator16of the robot by means of a fixing device17, which may be seen in FIG.1. This being the case, a contact-breaking device18is provided between the manipulator16of the robot, in particular the robot arm3, and the section11. This contact-breaking device18operates in such a way that when pressure is duly exerted on the laser hybrid welding head1, as would be the case when the laser hybrid welding head is being run along an object, the laser hybrid welding head1can be deflected accordingly by means of this contact-breaking device8, the only thing needed to activate the contact-breaking device18being the application of a defined force. The major advantage of a contact-breaking device18of this type resides in the fact that the laser hybrid welding head1is maintained in a defined spot or position and, when a defined force is applied to the laser hybrid welding head1, the latter is moved by the contact-breaking device18, and when force is applied to the laser hybrid welding head1again, it is returned to the original point or position by means of the contact-breaking device18.

The elements making up the welding torch5are a torch body19and a mounting body20, in which all the components needed for a standard torch are integrated. The welding torch5may be a MIG/MAG welding torch for running a MIG/MAG welding process, in other words an arc welding process6, it merely being necessary to modify the individual elements of the welding torch5, compared with the current state of the art, in a manner that will allow the mounting body20to be readily secured to and adjusted on the section11and set up a reliable wire feed to the arc welding process6and establish a very good contact for a delivered welding wire21with energy, in particular current and voltage.

Another contact-breaking device22is provided between the torch body19and the fixing body20, enabling a corresponding displacement of the torch body19relative to the fixing body20when a corresponding force is exerted on it, as described above. This contact-breaking device22is designed so that an essentially light force applied to the torch body19will suffice to trigger a corresponding displacement, in the same way as necessary to operate the contact-breaking device18for the entire laser hybrid welding head1.

The contact-breaking devices18,22have a sensor—not illustrated—which generates a signal accordingly when the contact-breaking devices18,22are activated. To this end, the contact-breaking devices18,22, in particular the sensors, are connected to a control system for the robot and/or to a welding apparatus—not illustrated—so that the control system can detect whenever one or both of these sensors is activated. As a result, continued displacement of the robot arm3, in other words the laser hybrid welding head1, or the welding process can be halted when a corresponding force is applied, thereby preventing damage to the individual components.

In the laser hybrid welding head1proposed by the invention, the cross jet guide device7is attached to an end face23of the section11, so that, in the embodiment illustrated as an example here—shown in FIG.1—the compressed air delivered via the passages14and15and the compressed air fed away via the passage13, is transferred directly to and from the cross jet guide device7. To this end, appropriate passages24to26are provided in the interior of the cross jet guide device7, running out of a housing of the cross jet guide device7. These passages24to26are disposed at one end of the housing27so that any lines required, in particular the passages13to15or the incoming line9and the outgoing line10, have to be disposed in a region at this end only.

In the embodiment illustrated as an example here, and more specifically shown inFIGS. 3to5, the cross jet guide device7is preferably L-shaped, so that the cross jet guide device7is preferably disposed or extends at a defined distance28underneath the laser4and the laser optical system or the optical focussing unit or a protective pane29with a matching protective monitoring window for the laser4. The housing27of the cross jet guide device7also has an orifice30or a recess, in which the cross jet8is generated, i.e. the cross jet guide device7has an orifice30through which a schematically indicated laser beam31is beamed from the laser4, so that the compressed air flows through the orifice30at an angle of preferably 90° C. with respect to the laser beam31so that a cross jet flow32is generated in the orifice30.

The cross jet guide device7used for this purpose is illustrated in detail inFIGS. 3to5,FIG. 3showing a plan view onto the housing27andFIGS. 4 and 5respectively showing an end-on view of the housing27—along section lines IV—IV and V—V indicated in FIG.3.

The cross jet guide device7may be made in the form of a single-piece or multi-part cast component or an injection-moulded part of aluminium or plastics, for example. Naturally, the housing27may be of any design structure known from the prior art, the only design requirement being that an orifice30must be provided and the orifice30must communicate with the passages24to26in the interior of the housing. Consequently, in the housing27of the cross jet guide device7, the passages24to26are laid out as an extension of the passages13to15of the section11, in other words as an extension of the incoming and outgoing lines9,10, the latter extending into the orifice30forming an outlet passage33and an oppositely lying inlet passage34to and from the orifice30at the end faces, i.e. the end-to-end orifice30is provided in the housing27of the cross jet guide device7for a laser beam31to extend through the orifice30, whilst the outlet passage33and an oppositely lying inlet passage34are provided at the end faces of the orifice30for the compressed air, in particular for the cross jet8or the cross jet flow32.

As a result, the compressed air is delivered and flows out of the outlet passage33into the orifice30and then flows into the inlet passage34disposed at the oppositely lying end, so that the compressed air forms or generates an air flow, in particular the cross jet flow32, in the orifice30. The guide aspects of the passages24and26as well as the shape of the inlet and outlet passages33,34may be of any design and are not restricted to that in the embodiment illustrated as an example here. It is merely necessary to ensure that a cross-flow or what is referred to as a cross jet8is created in the orifice30of the cross jet guide device7.

The housing27is advantageously designed to generate an incoming and outgoing airflow at an end or side face. However, it would also be possible for the intake and discharge of compressed air to be operated at different, in particular oppositely lying, end or side faces of the housing27.

Another option is to provide the housing27in a cuboid shape or an L-shaped design, in which case the orifice30will extend through the housing27and will be oriented in a substantially perpendicular arrangement on two oppositely lying side faces. The housing27may also be provided with an additional passage for discharging at least a part-flow of the compressed air. Discharging the compressed air in at least two part-flows makes it easier to carry away particles of dirt or welding debris.

The purpose of the cross jet guide device7, in particular the resultant cross jet8, is to shield the optical system of the laser4and the laser optics or optical focussing unit or the schematically indicated protective pane29disposed in front of these components, from welding splatter generated during a welding process. Accordingly, the cross jet8is disposed underneath the laser4and the laser optics or the optical focussing unit, in other words between the laser4and the region where the welding process is being operated by the laser4and the welding torch5. The cross jet guide device7, in particular the cross jet8, is set up so that the resultant cross jet flow32, in particular an air flow, is generated ion the manner schematically indicated by the arrows in FIG.3. The cross jet8, in particular the cross jet flow32, is preferably generated at a flow speed of between 100 and 600 m/s and/or the cross jet pressure is between 2.5 and 6 bar. The cross jet8is therefore able to generate a supersonic flow, what is known as a Laval nozzle being formed in the cross jet guide device7.

To enable the cross jet flow32, in particular the compressed air, to be fed away from the region of the laser hybrid welding head1, in particular away from the area of the arc welding process6, an appropriate passage26is provided in the cross jet guide device7for discharging the cross jet flow32, i.e. the cross jet flow32generated via the passages24,25of the cross jet guide device7flows through the orifice30of the cross jet guide device7into passage26and from there into passage13, in particular the outgoing line10, in the section11, so that welding debris picked up by the cross jet flow32, especially materials flung towards the laser4and the laser optics or the optical focussing unit, are carried via the outgoing line10away from the region of the laser hybrid welding head1. The outgoing line10is connected to a suction system, for example, so that an appropriate vacuum pressure can be generated in the outgoing line10, thereby enabling the cross jet flow32to be sucked out through the orifice30of the cross jet guide device7. To enable the cross jet flow32to be fed away through the inlet passage more efficiently, the inlet passage34is bigger in volume than the outlet passage33.

The essential feature of a laser hybrid welding head1of this type is that the cross jet8is generated at a specific distance from the arc welding process6because if a gas atmosphere—not illustrated—is being used as a shield and the cross jet guide device7were at too short a distance from it, the protective gas atmosphere would be drawn in the direction of the cross jet8by a vacuum pressure occurring around the cross jet8. This would mean that the arc welding process6could no longer continue to be shielded by the requisite gas atmosphere.

By setting up the cross jet8in this manner, an almost closed system is created inside the housing27of the cross jet guide device7, so that absolutely no or only slight air flows can be produced outside of the orifice30of the cross jet guide device7. This enables a very short distance to be left between the cross jet8or cross jet guide device7and the welding process, especially the arc welding process6, so that the structural dimensions of the laser hybrid welding head1can be significantly reduced, resulting in a considerable improvement in the handling of the laser hybrid welding head1. It goes without saying that a cross jet guide device7of this type could also be used in other applications, such as a pure laser welding process, to protect the laser4and the laser optics or the optical focussing unit from smoke or loose metal debris. The major advantage resides in the fact that the cross jet flow32occurs inside the orifice30only and no or only light air flows are created outside of this orifice30.

The special design of the cross jet guide device7also means that the laser4is exposed to attach at a restricted surface only because it is shielded from loose metal debris or welding splatter or smoke by the cross jet guide device7, in particular by the housing27itself, and it is only in the region of the orifice30through which the laser beam31is directed that these particles are able to get in front of the laser4or the laser optical system or the optical focussing unit. The majority of particles are therefore already kept away by the housing27and the remaining particles are carried into the orifice30by the cross jet flow32. Consequently, it is virtually impossible for welding splatter to penetrate as far as the laser4. The significant factor here is that because this area is limited to the orifice30, the nature and means of producing the cross jet8is made easy because it no longer needs to operate across a large surface area, which is the case with the open systems known from the prior art. To this end, the cross jet guide device7or housing27may be designed so that it at least partially encloses the co-operating the laser4and laser optical system or the optical focussing unit and the distance28from the housing to the laser4is screened off by designing the housing27accordingly so that lateral penetration of dirt or other foreign bodies to the parts to be protected, such as the laser4and laser optics or the optical focussing unit, can be prevented and ingress is only possible via the orifice30. This being the case, it is possible to generate a vacuum pressure in this region, in other words between the laser4and the cross jet guide device7, and this vacuum pressure may be branched off from the incoming line9. This can easily be arranged if at least one of the passages24or25has at least one bore in the direction of the laser4, as a result of which a part of the compressed air delivered can escape in the direction of the laser4, enabling an appropriate vacuum pressure to be generated in this region above the housing27.

The laser hybrid welding head1proposed by the invention also has one or more display units35—schematically indicated—by means of which the relative positions of the components can be displayed, i.e. starting from a predefined position or initial position, the components, in particular the laser4and the welding torch5, can be displaced in the X-, Y- and Z-directions relative to one another and displays or readings for these motion sequences can be indicated on the display unit35so that a specific relative positioning of the two components can be repeated at any time as and when necessary. Consequently, the laser hybrid welding head1may be positioned in readiness for a broad range of different welding processes whilst providing an easy means of re-setting to the corresponding initial values.

For example, the individual components, in particular the laser4and the welding torch5, can be linked to an electronic recording device or measuring device for mechanical motions known from the prior art—not illustrated—and the values generated by the recording device displayed on the display unit35. To this end, the display unit35may be disposed directly on the laser hybrid welding head1or in a central control device, for example, in which case the values are transmitted to the display unit35or a control system via lines. This will mean that a setting of the laser hybrid welding head1can be reproduced at any time by electronic means. Naturally, it would also be possible to attach the individual components to an electronic displacement system as to automate the displacement, in which case only the value representing the shift will need to be set, enabling the corresponding motion control system to take over the displacement control.

For the sake of completeness, it should also be pointed out that the individual components are connected to the requisite supply systems by lines, as schematically indicated. To this end, the laser4is connected via a supply line36to an appropriate power source. The welding torch5is also connected via a hose pack37to a welding apparatus. Another possibility would be to link the power source for the laser4directly to the welding apparatus so that the power needed for the laser4and the welding torch5is supplied from the welding apparatus.

As a result of the special design of the laser hybrid welding head1, no lines will be disposed in the region of the welding process at all, because they are all connected to the components at the end lying opposite. This will avoid situations where the laser hybrid welding head1is left hanging on a line or an object because there are no protruding lines around the components. This also means that the laser hybrid welding head1may be used in mirror image without changing the robot, in particular the programmed motion, since there is no need to make allowance for any lines or parts which might pose an obstacle, and the laser hybrid welding head1can even be used at points which are a difficult to access, as a result of its special design.

In another embodiment illustrated as an example—FIG.6—the laser hybrid welding head1is depicted in a plan view, the section11again being disposed at the centre. The individual components are attached to this section11in the manner described above.

As mentioned above, the incoming line9and the outgoing line are no longer integrated in the mounting element2and in the section11but extend parallel with and attached to the section11, which is arranged so that it extends between the two components, in particular the laser4and the welding torch5. In this embodiment, the section11also has no internally lying passages13to15.

This arrangement also enables the laser hybrid welding head1to be set up in a symmetrical structure without any protruding lines. Since standard, commercially available mounting systems may be used to mount the individual components, a specific description of the structure can be dispensed with as it is more or less as described with reference to the embodiments illustrated inFIGS. 1to5.

It should merely be pointed out that in the embodiments illustrated as examples inFIGS. 1to6, the components, in particular the laser4and the laser optics or the optical focussing unit and the welding torch5, are mounted at both ends of the mounting element2, in particular the section11, whereas laser hybrid welding heads known from the prior art are constructed so that the laser and the welding torch are disposed on one side of the mounting plate, whilst the oppositely lying side is used for the connection to the robot, in particular the robot arm. This layout makes the laser hybrid welding head1excessively wide and all the more difficult to manipulate.

FIGS. 7to9illustrate another example, this time an embodiment of a modular laser hybrid welder or modular laser hybrid welding head1, consisting of at least one mounting element2, in particular the section11, on which components such as a laser4and the laser optics or the optical focussing unit and elements of a torch or a welding torch5for a welding process are mounted. The modular laser hybrid welder additionally has a device for forming a cross jet8(not illustrated), in particular a cross jet guide device7, which is connected via at least one incoming line9and an outgoing line10to a compressed air supply system.

The torch or welding torch5is made up of several individual modules, at least one of which modules, in particular the torch body19, can be changed in order to run a range of different joining process, in particular a welding process or a soldering process. Accordingly, the torch body19can be changed in order to set up a MIG/MAG welding process, a TIG/WIG welding process, a double-wire welding process, a plasma welding process or for laser cold-wire soldering, laser hot-wire soldering or laser welding without an arc, i.e. different torch bodies19used for different joining processes can be connected to a module of the welding torch5so that one and the same laser hybrid welding head1can be used to run different processes without having to change the entire welding torch5, in particular the modules.

As a result, the laser hybrid welder can advantageously be very rapidly modified to run a whole range of different welding processes. One particular advantage resides in the fact that, because of the modular design, the task of changing the torch body19can be automated and this changeover can be operated in the manner used as standard in robot technology on the basis of a tool changeover. This being the case, it has been found to be of particular advantage if any additional components or add-on modules, such as an external wire feed device or an additional welding torch5or torch body19, not illustrated, are already attached to the section11or the latter is connected to the torch body19, dispensing with the need for mechanical changes or settings.

The welding torch in this instance will consist of a drive module40, a mounting module41and the torch body19and it will also be possible to connect additional modules, for example an external wire feed module. To enable the torch body19to be changed, the torch body19is connected to the mounting module41of the welding torch5by means of a connecting device42, in particular a screw connection or plug and socket connection. The individual modules, in particular the drive module40and the mounting module41, are attached to the section11, whereas the torch body19is secured to the mounting module41of the welding torch. Consequently, when the torch body19is replaced, the positions of the modules attached to the section11remain unchanged so that the settings relating to the laser4, in particular the laser beam, also remain unchanged. As a result, other torch bodies19can be made to a matching design in terms of their length, thereby enabling an optimum welding process. It is preferable if individual torch bodies19are always made to the same standard length and as a precision component. However, the torch bodies19may be of different shapes, as is the case inFIG. 9, for example. In this embodiment, the torch body19is specially designed for a soldering process and the welding material, in particular the welding wire21, is fed at a different angle than is the case for a welding process.

In another alternative, the add-on modules may also be attached to the section11. The section may be pre-mounted with appropriate fixing means for this purpose, which again will enable mounting and dismantling processes to be automated. As a result of the combined design of the welding torch5for both soldering and welding, it will then be possible to generate an inert gas atmosphere during a soldering process because all the delivery lines needed for this purpose will be to hand.

For the sake of good order, it should finally be pointed out that, in order to provide a clearer understanding of the laser hybrid welding head1, it and its constituent parts are illustrated to a certain extent out of proportion and/or on an enlarged scale and/or on a reduced scale.

The independent solutions proposed by the invention and the underlying objective may be found in the description.

Above all, the individual features of the embodiments illustrated inFIGS. 1,2,3,4,5;6may be construed as independent solutions proposed by the invention in their own right. The related objectives and solutions proposed by the invention may be found in the detailed descriptions of the drawings.