LASER PROCESSING HEAD FOR LASER WIRE DEPOSIT

Description

[0001] The invention relates to a laser processing head designed for laser wire deposition welding. The laser processing head can process various wire-shaped materials, in particular wires with outer diameters of less than 1.6 mm, preferably less than 1 mm, and generally less than 0.6 mm. This allows coatings or three-dimensional contours to be applied to workpiece surfaces, as well as additive manufacturing of three-dimensional workpieces or components.

[0002] Such laser processing heads are well known. The goal is often to achieve centralized wire feeding and melting with the energy of a laser beam in the most homogeneous form possible. To achieve this, the laser radiation must be directed radially from the outside onto a centrally positioned and conveyed wire-shaped material in order to melt it as homogeneously as possible.

[0003] For this purpose, a laser beam is directed onto beam-deflecting reflective elements, so that a single reflected beam or several reflected partial beams are reflected toward a plane where the reflected laser beams intersect. The wire-shaped material is to be conveyed into this plane and melted there. This plane is located above the surface of a workpiece onto which the material is to be deposited by laser wire deposition welding.

[0004] The laser beam is typically emitted from a laser source and introduced into an optical unit via an optical fiber. There, it encounters the laser beam, reflecting elements as described above, and is then reflected by several partial beams into the plane with the intersection point. The wire-shaped material should be fed centrally relative to the partial beams, which impinge at a common intersection point, to ensure homogeneous heating and optimal material utilization.

[0005] This has so far been achieved by adjusting the alignment of the laser beam and in particular that of the optical fiber in relation to the reflective elements.

[0006] This results in considerable effort, as optical alignment must be performed at several separate positions and elements of a laser processing head. Aligning the laser beam, and especially an optical fiber, is particularly problematic and prone to failure during operation or during a new commissioning.

[0007] For example, CN 107 322 166 A, CN 107 414 305 A, CN 106 583 726 A and CN 106 392 314 A disclose laser processing heads for build-up welding, in which partial beams of a laser beam with reflective elements are used for build-up welding.

[0008] CN 202 367 348 U discloses the basis for the preamble of claim 1 and differs from these known technical solutions in that an annular mirror is used.

[0009] From DE 10 2009 038 659 A1 an upper emission extraction system for laser processing systems was known.

[0010] CN 107 227 455 A describes a laser processing head for deposition welding.

[0011] JP 2001 314985 A concerns laser beam welding.

[0012] CN 106 312 304 A describes a laser processing head for wire deposition welding in which a laser beam is split into partial beams.

[0013] It is therefore an object of the invention to provide possibilities for a simplified and safe optical adjustment of a laser beam in relation to the supplied wire-shaped material, even during continuous operation.

[0014] According to the invention, this object is achieved with a laser processing head having the features of claim 1. Further developments and embodiments of the invention can be realized with features specified in subordinate claims.

[0015] In the laser processing head according to the invention, a laser beam (6) is directed through an optical unit (4) onto a pyramid-shaped element (8) and, in the process, onto at least three reflective surfaces of the pyramid-shaped element (8.1) aligned at equal angular distances from one another. The partial beams (6.1, 6.2, 6.3) reflected by the reflective surfaces (8.1) impinge on reflective surfaces (8.2) arranged radially outward on a support element. The reflective surfaces (8.1, 8.2) are oriented such that the partial beams (6.1, 6.2, 6.3) reflected by them intersect in a common plane (6.4).

[0016] The housing (1) contains an internal wire feed (2) with an outlet nozzle (2.1) for a wire-shaped material (3) arranged in the direction of a workpiece to be machined, which can be melted with the energy of the partial beams (6.1, 6.2, 6.3) impinging on the wire-shaped material (3). The outlet nozzle (2.1) is arranged in front of the plane in which the reflected partial beams intersect (6.4) during the feed motion of the wire-shaped material (3).

[0017] The pyramid-shaped element (8) and the reflective surfaces (8.1, 8.2) are formed on a single optics support element (5.1). The optics support element (5.1) is arranged and fixable in the optics adjustment unit (5) such that it can be displaced in two directions perpendicular to the optical axis of the laser beam (6) or perpendicular to the central longitudinal axis of the wire-shaped material (3) adjacent to the outlet nozzle (2.1) for adjustment.

[0018] The optics carrier element (5.1) can thus be moved in axes aligned perpendicular to each other (x and y axes of a Cartesian coordinate system) for an optics adjustment (5) of the partial beams (6.1, 6.2, 6.3) and locked in the desired position.

[0019] This reduces the essential adjustment of the optical system to the optics adjustment (5) of a single element, namely the optics carrier element (5.1).

[0020] The pyramid-shaped element (8) should be positioned on the optics support element (5.1) so that its tip is centered between the reflecting surfaces (8.1). This ensures, with precise adjustment of the optics support element (5.1), that the partial beams (6.1, 6.2, 6.3) reflected by the reflecting surfaces of the pyramid-shaped element (8.1) have the same energy and the same cross-sectional areas of the partial beams.

[0021] The optics carrier element (5.1) is a monolith formed from a single material to which no individual part present on the optics carrier element (5.1) has been attached as a result of assembly. An optics carrier element (5.1) is made in one piece from a semi-finished product and can be manufactured by machining and / or an additive manufacturing process.

[0022] Preferably, an optical carrier element (5.1) should be made of copper or a copper alloy.

[0023] At least one cooling channel (8.4) and cooling grooves (8.5) are formed on or in the optics carrier element (5.1), which can be connected to a supply and discharge line for a cooling medium. This allows distortion at different operating temperatures to be largely compensated for. The at least one cooling channel (8.4) can also be formed directly on or in the optics carrier element (5.1) and, if necessary, sealed from the environment with a seal. A seal can be arranged between the open cooling channel (8.4) or openings in the cooling channel (8.5) and the mounting unit (14), the protective glass module (16), and the housing (1).

[0024] The optics carrier element (5.1) can be adjusted in two perpendicular axes by means of two adjusting elements (5.2) provided with a thread perpendicular to each other. In the simplest case, these adjusting elements (5.2) can be adjusted manually. However, a motor drive can also be used for the translational movement of the optics carrier element (5.1) in the plane. Depending on the pitch of the thread, the accuracy of the optics adjustment (5) can be increased. Threads with a very small pitch lead to high positioning and adjustment accuracy. Such threads also have a high degree of self-locking, so that an additional locking option is unnecessary. Furthermore, the adjusting elements (5.2) can be firmly locked against each other in the respective XY axis. Thread pitches of 0.2 are preferred.

[0025] Several external wire feeds (10, 11, 12, 13) can preferably be provided for feeding different wire materials (3) and arranged outside the housing (1). A wire-shaped material (3) can be fed from each of the external wire feeds (10, 11, 12, 13) to the internal wire feed (2), wherein a funnel-shaped inlet opening (2.2) for introducing a wire-shaped material (3) from one of the external wire feeds (10, 11, 12, 13) into the internal wire feed (2) should be formed on the end face opposite the outlet nozzle (2.1).

[0026] External wire feeds (10, 11, 12, 13) can be equipped with a motor drive that can realize the feed movement of the respective wire-shaped material (3). Advantageously, the external wire feeds (10, 11, 12, 13) can also be provided with a device for preventing twisting of the wire-shaped material (3) fed from a roll.

[0027] Wire-shaped material (3) can be conveyed from an external wire feed (10, 11, 12, 13) into the funnel-shaped area (2.2) of the internal wire feed (2) and from there through the internal wire feed (2) to the outlet nozzle (2.1) in the area where the partial beams intersect (6.4). The conveying takes place within the housing (1) in such a way that no adverse influence on the wire-shaped material (3) by laser radiation (6) is possible between the external wire feed (10, 11, 12, 13) and the outlet nozzle (2.1). This can be achieved by positioning (5) the wire-shaped material (3) within the housing, in which the partial beams (6.1, 6.2, 6.3) are guided through areas (14.2) in which no wire-shaped material (3) can come into contact with the partial beams (6.1, 6.2, 6.3).

[0028] Advantageously, a fume extraction system (9) can be provided on the housing (1) on the end face facing the workpiece. The fume extraction system (9) can be formed by a cone (9.7) that can be screwed onto the housing (1). In the direction of the workpiece, such a cone (9.7) should have an opening through which the reflected partial beams (6.1, 6.2, 6.3) and a wire-shaped material (3) can exit. A shielding gas should also be directed through this opening onto the workpiece area to be machined.

[0029] The fume extraction system (9), particularly a cone, should be formed with several openings (9.2) arranged around the outer circumference, which open into a common extraction channel (9.1). The sum of the free cross-sectional areas of the openings (9.2) through which fume is extracted from the processing area of the respective workpiece should correspond to the free cross-sectional area of the common extraction channel (9.1). However, the sum of the free cross-sectional areas of the openings (9.2) can also be a maximum of 10% larger or smaller than the free cross-sectional area of the extraction channel (9.1) in order to ensure sufficiently effective extraction of fume from the processing area.

[0030] The nozzle-shaped element (9.7) of the flue gas extraction system (9), which can be attached to the housing (1), can be designed with at least one cooling channel (9.3) that can be connected to an inlet and outlet (9.4, 9.5) for a cooling medium. In this case, the inlet and outlet (9.4, 9.5) can be routed through the extraction channel (9.1) to or from outside the mounting unit (14) and the housing (1). The cross-sectional area required for this purpose inside the extraction duct (9.1) should take into account the conditions of claim 8, i.e. the sum of the free cross-sectional areas of the openings (9.2) of the free cross-sectional area of the extraction duct (9.1), taking into account the loss of free cross-sectional area caused by the supply and discharge (9.4, 9.5) for a cooling medium in the at least one cooling duct (9.3) on the flue gas extraction (9).

[0031] The internal wire feed (2) and in particular the outlet nozzle (2.1) should also be movable and lockable perpendicular to the plane in which the optics carrier element (5.1) is two-dimensionally movable and adjustable, for a defined positioning (15) in relation to the plane in which the reflected partial beams intersect (6.4). This enables precise positioning (15) in the Z-axis direction of the wire-shaped material (3), which enters the sphere of influence of the intersecting reflected partial beams (6.1, 6.2, 6.3), to be achieved. This can be achieved, for example, with a groove and key solution (2.3). This allows the internal wire feed (2) to be positioned in the Z-axis direction by translational displacement and, if necessary, fixed in a desired position by means of a locking device, e.g., a screw.

[0032] The invention will be explained in more detail below by way of example.

[0033] Showing: Figure 1 shows a perspective and an exploded view of an example of a laser processing head according to the invention; Figures 2a, 2b show two views of an optical carrier element (5.1) that can be used in the invention; Figures 3a - 3c show three views of a smoke exhaust outlet (9) on a laser processing head; Figures 4a, 4b show two views that should exemplify the beam guidance of the laser beam (6), the three partial beams (6.1, 6.2, 6.3) formed with it, and the feeding of wire-shaped material (3); and Figures 5a, 5b show two views of a possible design in which wire-shaped material (3) can be fed to an internal wire feed (2) using several external wire feeds (10, 11, 12, 13).

[0034] In Figure 1An example of a laser processing head according to the invention is shown. Arranged in a housing (1) are an internal wire feed (2) for supplying wire-shaped material (3), optical components (4) for shaping a laser beam (6), and an optical carrier element (5.1) for deflecting the laser beam (6) and splitting the laser beam into three partial beams (6.1 - 6.3).

[0035] An optical unit (4) for an optical fiber (4.1) is attached to the housing (1), through which the laser beam (6) is directed onto reflecting surfaces (8.1) of a pyramid-shaped element (8) and reflecting surfaces (8.2) formed on an optical carrier element (5.1).

[0036] On the opposite end of the laser processing head, there is a fume extraction system (9) with a screw-on cone (9.7) with an opening through which the wire-like material (3) can be fed into the area of influence of the partial beams (6.1 - 6.3) intersecting in a plane (6.4), in the direction of a workpiece (not shown). An extraction channel (9.1) is provided on the cone (9.7), which is connected on the suction side to a unit (not shown) that achieves a negative pressure. The fume extracted through the extraction channel (9.1) can be directed to a filter unit (also not shown).

[0037] In the housing (1), between the optics support element (5.1) and the smoke gas extraction system (9), there is a protective glass module (16) with at least one, in this example, three protective glasses through which the three partial beams (6.1 - 6.3) radiate toward the plane where they intersect (6.4). The protective glasses can be used to protect the other components contained in the housing (1), in particular the optical components (4) and the optics support element (5.1), from contamination. The protective glass module (16) and / or the protective glasses should be replaceable.

[0038] Furthermore, the laser processing head features an XYZ wire adjustment (15) for adjusting the wire-shaped material (3) to the intersection point of the three partial beams (6.4), as well as a mounting unit (14). Various external wire drives (10, 11, 12, 13), other optical units from other laser manufacturers (7), and a collision and safety shutdown (17) can also be mounted.

[0039] In Figure 2aa perspective view of an optics carrier element (5.1) is shown. The optics carrier element (5.1) is designed such that the tip of a pyramid-shaped element (8) is arranged at the center. The laser beam (6), focused by the optical components, strikes the tip and the three adjoining reflecting surfaces (8.1) inclined at an angle. The three reflecting surfaces (8.1) of the pyramid-shaped element (8) are aligned and arranged with respect to one another such that the incident laser beam (6) is split into three partial beams (6.1 - 6.3), and each partial beam (6.1 - 6.3) strikes a reflecting surface (8.2) formed on the optics carrier element (5.1). The reflecting surfaces (8.2) are aligned such that the partial beams (6.1 - 6.3) are each reflected through an opening (8.3) in the optics carrier element (5.1) at an angle directed obliquely towards each other in the direction of a workpiece to be machined.The reflections occur in such a way that the partial beams (6.1 - 6.3) intersect in a plane located above the surface of a workpiece to be machined, where wire-shaped material (3) is also fed from the outlet nozzle (2.1). Figure 2b It can also be seen that a cooling channel (8.4) and cooling grooves (8.5) are formed in the optics carrier element (5.1), through which a cooling medium, in particular cooling water, can be passed for cooling.

[0040] The opening in the smoke extraction system (9) is selected to be large enough so that in addition to the outlet nozzle (2.1) of the internal wire feed (2), the partial jets (6.1 - 6.3) can also pass through this opening without any problems.

[0041] The optics carrier element (5.1) is made of copper or a copper alloy and is manufactured as a single piece by machining.

[0042] The optics carrier element (5.1) is guided in a guide carriage (optical adjustment) (5), which is also fastened in the housing (1). The optics carrier element (5.1) and guide carriage (5) are aligned perpendicular to the optical axis of the laser beam (6). The optics carrier element (5.1) can be displaced two-dimensionally in this plane, which is aligned perpendicular to the optical axis of the laser beam (6), and can thus be adjusted relative to the optical axis, in particular with its reflective surfaces (8.1) formed on the pyramid-shaped element (8) and therefore necessarily also with the reflective surfaces (8.2). For this purpose, two threaded adjustment elements (5.2) aligned at right angles to one another can be used, with which the optics adjustment (5) can be displaced in one axial direction, preferably in the X- or Y-axis direction, for adjustment and can be locked against one another.

[0043] In the Figures 3a to 3cA fume extraction system (9) is shown. A nozzle-shaped cone (9.7) is attached to the housing (1) by a screw connection. An opening (9.6) tapering conically toward a workpiece is formed in the cone (9.7). The opening allows the outlet nozzle (2.1) containing the wire-like material (3) and the three partial jets (6.1 - 6.3) to pass through this opening without striking the wall of the fume extraction system (9) and without being exposed to inert gas.

[0044] Furthermore, in this example, the flue gas extraction system (9) features openings (9.2) in the form of bores, through which flue gas generated during processing can be drawn in and discharged via the extraction channel (9.1). The free cross-sectional areas of the openings (9.2) and the extraction channel (9.1) are dimensioned as explained in the general part of the description. The openings (9.2) have equal free cross-sectional areas through which flue gas generated during processing can be drawn in. They are arranged at equal angular intervals around the circumference of the flue gas extraction system (9).

[0045] The flue gas extraction system (9) also contains a cooling channel (9.3) connected to a coolant supply (9.4) and a coolant outlet (9.5). In this example, the coolant supply (9.4) and the coolant outlet (9.5) are routed through the extraction channel (9.1) so that they do not interfere with the flow and cannot be damaged from the outside. Here, too, the dimensioning specifications regarding the free cross-sectional areas stated in the general part of the description should be observed. The flue gas extraction system (9) is also made of copper or a copper alloy and can also be manufactured additively.

[0046] In Figures 4a and 4b the advantageous guidance of the laser beam (6) with its partial beams (6.1 - 6.3) as well as the feeding of the wire-shaped material (3) with the internal wire feed (2) is illustrated.

[0047] The focused laser beam (6) strikes the three reflective surfaces (8.1) of the pyramid-shaped element (8), and the resulting three partial beams (6.1 - 6.3) are each reflected onto a reflective surface (8.2) formed on the optics carrier element (5.1). By means of the reflective surfaces (8.2), the three partial beams (6.1 - 6.3) are aligned towards one another at an oblique angle so that they intersect in a common plane (6.4). This plane (6.4) is arranged in the direction of a workpiece to be machined in front of the outlet opening of the outlet nozzle (2.1), from which the wire-shaped material (3) and protective gas for shielding the molten pool (2.4) emerge, so that the wire-shaped material (3) is uniformly illuminated from three sides by the three partial beams (6.1 - 6.3) is irradiated and heated so that a uniform all-round heating of the wire-shaped material (3) can be achieved, which leads to its complete melting in the irradiated area.

[0048] The wire-shaped material (3) is fed into the center of the three intersecting partial beams (6.1 - 6.3).

[0049] With the Figures 5a and 5b The aim is to address the possibility of feeding different wire-shaped materials (3) or the possibility of using several external wire feeds (10, 11, 12, 13) for a virtually uninterrupted processing option if the same wire-shaped material (3) can be fed with several external wire feeds (10, 11, 12, 13).

[0050] The external wire feeds (10, 11, 12, 13) are each equipped with their own drive for advancing the respective wire-shaped material (3). They can be activated sequentially to achieve a change in the supplied wire-shaped material (3) or to switch to another external wire feed (10, 11, 12, 13) upon reaching the end of a wire-shaped material (3) of one external wire feed (10, 11, 12, 13).

[0051] When switching from one external wire feed (10, 11, 12, 13) to another, the wire-like material (3) conveyed by the subsequently activated external wire feed (10, 11, 12, 13) is guided into the funnel-shaped region (2.2) located on the end face of the internal wire feed (2) opposite the outlet nozzle (2.1). The newly fed wire-like material (3) can then, with the aid of the funnel-shaped region (2.2), thread itself into the bore extending as far as the outlet nozzle (2.1) for the wire-like material (3), without any further action or mechanism being required.

Claims

1. A laser processing head designed for laser wire cladding, in which a laser beam (6) is directed through a housing (1) onto a pyramid-shaped element (8) and onto at least three reflective surfaces (8.1) of the pyramid-shaped element (8) which are aligned at equal angular distances from one another, and the partial beams (6.1-6.3) each reflected from the reflective surfaces (8.1) impinge on reflecting surfaces (8.2) arranged radially on the outside of an optics carrier element (5.1), the reflecting surfaces (8.2) being aligned such that the partial beams (6.1-6-3) reflected on them are aligned such that they intersect in a common plane, and an internal wire feeder (2) is arranged in the housing (1), with an outlet nozzle (2.1), arranged in the direction of a workpiece to be machined, for a wire-shaped material (3) which can be melted with the energy of the partial beams (6.1-6.3) impinging on the wire-shaped material (3), wherein the outlet nozzle (2.1) is arranged in front of the plane in which the reflected partial beams (6.1-6.3) intersect as the wire-shaped material (3) advances; characterised in that the pyramid-shaped element (8) and the reflective surfaces (8.2) are formed on a single optics carrier element (5.1), and the optics carrier element (5.1) is arranged and can be fixed in an optics adjustment (5) in such a way that it can be displaced in two axes aligned perpendicular to the optical axis of the laser beam (6) or perpendicular to the central longitudinal axis of the wire-shaped material (3) in connection with the outlet nozzle (2.1), wherein the optics carrier element (5.1) is a monolith which is formed from a single material and no individual part present on the optics carrier element (5.1) is attached to the optics carrier element (5.1) as a result of assembly and which is at the same time a central displacement element of the two perpendicular to the optical axis of the laser beam (6) or perpendicular to the central longitudinal axis of the wire-shaped material (3) to the optics adjustment (5).

2. The laser processing head according to claim 1, characterised in that at least one cooling channel (8.4) and cooling grooves (8.5) are formed on or in the optics carrier element (5.1), which can be connected to an inlet and outlet (9.4, 9.5) for a cooling medium.

3. The laser processing head according to any one of the preceding claims, characterised in that the optics carrier element (5.1) can be adjusted in the two axes aligned perpendicular to one another by means of two adjustment elements (5.2) provided with a thread perpendicular to one another.

4. The laser processing head according to any one of the preceding claims, characterised in that a plurality of external wire feeders (10, 11, 12, 13) are provided for a feed of different wire materials (3) and a wire-shaped material (3) can be fed from the external wire feeders (10, 11, 12, 13) to the internal wire feeder (2), wherein a funnel-shaped inlet opening (2.2) for the introduction of a wire-shaped material (3) from one of the external wire feeders (10, 11, 12, 13) into the internal wire feeder (2) is formed at the end face opposite the outlet nozzle (2.1).

5. The laser processing head according to any one of the preceding claims, characterised in that a fume extraction system (9) is provided on the housing (1) and on a mounting unit (14) on the end face facing a workpiece.

6. The laser processing head according to the preceding claim, characterised in that the fume extraction system (9) is formed with a plurality of through-holes (9.2) arranged around the outer circumference, which open into a common extraction channel (9.1).

7. The laser processing head according to one of the two preceding claims, characterised in that the sum of the free cross-sectional areas of the through-holes (9.2), through which fumes are extracted from the machining area of the respective workpiece, corresponds to the free cross-sectional area of the common extraction channel (9.1), or the sum of the free cross-sectional areas of the through-holes (9.2) is at most 10 % larger or smaller than the free cross-sectional area of the extraction channel (9.1) and thus the flow inlet and flow outlet have the same, or at least almost the same, cross-sections.

8. The laser processing head according to any one of the three preceding claims, characterised in that the through-holes (9.2) guide the fumes in an extraction channel (9.1) and then in a circular tubular element (14.1), which can be attached to the mounting unit (14), to a device for extracting welding fumes.

9. The laser processing head according to the preceding claim, characterised in that the nozzle-shaped fume extraction system (9), which can be attached to the housing (1) and to the mounting unit (14) and XYZ wire adjustment (15), is designed with at least one cooling channel (9.3), which can be connected to an inlet and an outlet (9.4, 9.5) for a cooling medium.

10. The laser processing head according to the preceding claim, characterised in that the inlet and outlet (9.4, 9.5) are guided through the extraction channel (9.1) through the tubular element (14.1) of the mounting unit (14) and the cross-sectional area required for this takes into account the conditions of claim 8.

11. The laser processing head according to one of the preceding claims, characterised in that the internal wire feeder (2) and in particular the outlet nozzle (2.1) can be displaced and adjusted perpendicularly to the plane in which the optics carrier element (5.1) can be displaced and adjusted in two dimensions for a defined positioning in relation to the plane in which the reflected partial beams (6.1-6.3) intersect (6.4).