EP1247878B1 - Apparatus for powder coating by laser - Google Patents

Description

The invention relates to a device for laser coating of component inner surfaces with a particular powdery additional material, after the preamble of claim 1 or 4.

Devices for laser powder coating of mechanically highly loaded component surfaces are known in numerous embodiments.

Thus, in the device known from DE 196 43 029 A1 of the above mentioned type by means of a rotatable, optically with a Nd: YAG solid-state laser associated coating lance cylinder liners with a high silicon content Aluminum powder coated so as to be wear resistant To produce tread in aluminum crankcases. At the same time, the laser beam becomes guided in a light guide from the solid-state laser to a rotary guide, which allows an endless rotation of the flanged coating lance. At the rotation guide, the laser beam is coupled out of the light guide, collimated and then passes free-radiating through the lance to a deflection and Focusing optics, where the beam is deflected to the cylindrical surface to be coated and being focused. In addition to the lance integrated supply lines for cooling media, powder material, inert gas and a purge gas for generation one of the exit window of the laser beam at the lance tip frereiblasenden Cross-Jets. The coating is done by immersing the lance in the Cylinder bore, where the powder via a jet nozzle to the coating site blown out and melted there in the laser beam. By the simultaneous Turning and moving the coating lance are spiraling adjacent caterpillars that have a continuous tread coating form. Due to the inherent beam parameter product (Beam divergence and Strahltaillierung) of the solid state laser are such devices however, to a relatively low length / diameter ratio the coating lance limited so that they for full-surface coating lean cylinder bores or other hard-to-reach component cavities are unsuitable.

In another of EP-A-950 461, JP-A-03128183, JP-A-07292 481, EP-A-418 519 or US-A-5 426 278 of coating equipment is the dipping into the workpiece bore Coating lance in a rear, non-rotating lance part with one in this coaxially mounted optical fiber and a front, rotating Lancet part divided, which with the interposition of a pivot bearing and a rotary drive to the nichtrotierendenh lance part connects and in which the focusing and deflection optics are either coaxial or off-center is arranged to the axis of rotation. The laser light guide takes place in rotating lance either turn over a free jet or with Consideration of the eccentric arrangement of the focusing and deflection system via a second optical fiber piece in the coating lance, which is of the Optical fiber end in the non-rotating lance part eccentrically bent to the focusing system runs at the lance tip. In these known coating devices poses the problem that not only an optical rotary coupling for the second light guide piece or a free-jet guide, but in addition also the entire, consisting of pivot bearing and rotary drive unit within the coating lance must be accommodated, with the consequence that these devices also require a correspondingly large lance diameter and therefore also for the full-surface coating of component inner surfaces high slenderness are unsuitable.

The object of the invention is the coating device of the aforementioned To train in a structurally simple way so that even difficult to access Component inner surfaces, and in particular the deeper surface sections high-tonnage cylinder bores, easily and with high To coat radiation efficiency.

This object is achieved by the specified in claim 1 or 4 Coating device solved.

With the coating device according to the invention is for the entire coating lance a very small lance cross section with virtually any Lance length required and at the same time a very low-loss energy transfer in the coating lance especially of laser beams with high Achieved jet parameter product, without the need for elaborate lens systems or separate light guide pieces in the inside of the lance or one likewise elaborate formation of the coating lance as an optical waveguide requirement.

In this case, the laser light guide, which rotates with the coating lance, extends according to a first variant of the invention according to claim 1 throughout over the entire lance length of the device head outside of the component inner surface to the lance tip, the laser radiation via an optical rotation coupling on the head, but preferably directly from the on this arranged and also co-rotating laser source, in the device side Fiber optic end is coupled. In this case, the coating device not limited to linear lances, but it can be without also other, depending on the application differently curved Use lance shapes and a deflecting mirror at the lance tip to dispense with the lateral beam deflection in a simple way that the Light guide is bent at auskoppelseitigen end portion or one for Has light guide axis inclined end face, while in the second variant The invention of claim 4, wherein the laser light guide is in the coating lance takes place by a non-rotatably arranged light guide, which in a likewise rotatably connected to the device head inner tube of the Coating lance exactly coaxial with the axis of rotation of the coating lance fixed is, even then results in a further improved energy transmission, if the Laser source is located away from the device head, since in this case the Optical fiber in optically and structurally favorable way from the lance tip to the Laser source can be formed continuously free of rotation. The between Lanzenaußen- and inner tube existing annulus is preferably as cooling and / or working fluid, e.g. Protective gas channel used.

In a particularly preferred embodiment of the invention is as a laser source Diode laser provided, the in itself unfavorably high beam parameter product because of the superior transmission quality of the invention Coating device even with a very slender designed coating lance without affecting the effectively applied laser power remaining in the Remaining but much better performance (socket efficiency) as a conventional solid, e.g. Nd: YAG laser owns. Furthermore, the Process monitoring expediently facilitated by that in the light guide from the lance tip in the opposite direction to the laser beam optical, e.g. the Melting temperature at the respective coating location indicating infrared signals recycled and decoupled for process control at the device head. To the radiation characteristics of the laser beam at the lance tip to simple Way to adapt to the particular application, contains this expediently a replaceable focusing optics.

Fig. 1a, b

ein Beschichtungsgerät in einer ersten Ausführungsform der Erfindung im Längs- (a) und im Querschnitt (b); und

Fig.2

eine der Fig. 1 entsprechende Darstellung eines zweiten Ausführungsbeispiels der Erfindung.

The invention will now be described with reference to two highly schematically illustrated in the drawings embodiments. This shows in

Fig. 1a, b

a coating apparatus in a first embodiment of the invention in the longitudinal (a) and in the cross section (b); and

Fig.2

a representation corresponding to FIG. 1 of a second embodiment of the invention.

The coating apparatus shown in Fig. 1 contains a main components High-power diode laser 1, one of these via a light guide 2 optically coupled device head 3 and a coating lance 4, which at a Rotary guide 5 of the device head 3 mounted and by means of a drive motor. 6 including a slip clutch 7 about a central axis A-A endlessly rotatable is driven. The light guide 2 passes through the device head 3 in a firmly connected to this, to the axis A-A coaxial standpipe 8 continuously to the lance tip and is at the standpipe end by means of a Faserendsteckers 9 and one between this and the rotating outer tube 10 of the coating lance 4 effective ball bearing 11 exactly centric attached to the axis of rotation A-A coating lance 4.

In the area of the lance tip, a lance tube 10 co-rotates with the latter, replaceable insert 12 with a collimating optics 13 and a Turning and focusing mirror 14 attached. The end of the light guide divergent emerging laser beam is rotated by the light guide axis Collimating optics 13 converted into an axis-parallel light beam and from the deflecting mirror 14 through a protective glass window 15 through to be coated Component inner surface 16, such as the cylinder surface of an engine block, redirected and focused.

The coating device is completed by the outside of the lance tube 10 attached Powder and gas supply lines 17, 18, via which the coating powder, such as a high-silica aluminum powder, and a protective gas on the focus region of the laser beam are blown out, and one in the outer tube 10 from the device head 3 to the lance tip extending compressed air channel 18 for generating a the protective glass window 15 frereiblasenden cross-jet and a Cooling water circuit for cooling the distal end of the optical fiber, which a Coolant flowed through, in the region of the fiber end plug in the annulus between Stand and lance tube 8, 10 arranged cooling water jacket 20 and associated supply and return channels 21, 22 in the lance tube 10 (Fig. 1b) contains.

When coating the cylinder surface 16, the over the powder feed line 17 to the focus region inflowing powder coating by the laser beam melted, and by rotation of the coating lance 4 and simultaneous Displacement of the device head 3 in the direction of arrow P arise spirally Adjacent coating beads through which a large area Produce tread coating. Because of the virtually arbitrarily large Length / cross-sectional ratio of the coating lance 4 can this way cylinder surfaces 16 high slenderness or other, poorly accessible component inner surfaces with low laser power losses be coated. Furthermore, signals for process monitoring can be obtained z. B. temperature-indicating infrared signals from the coating site traverse in the opposite direction to the laser beam in the light guide 2 to the device head 3, where she has a semi-transparent mirror element to a process control unit (not shown), for example for thermal process regulation of the coating process, are decoupled.

The embodiment shown in Fig. 2, where the one described above Embodiment corresponding components by a 100 increased Reference numerals are different from those in the first Line in that the arranged in the coating lance 104 light guide 102 is not arranged in a stationary standpipe, but with the Coating lance 104 co-rotated. The laser beam of the diode laser 101 becomes to the device head 103 via a permanently connected to this, another Optical fiber 102 'transmitted and passes through an optical rotation coupling 23 in the rotating optical fiber 102. In the area of the lance tip are the lance tube 110 and the optical fiber 102 is bent so that the laser beam at the optical fiber end obliquely to the axis of rotation A-A of the coating lance 104 emitted and by a downstream, again interchangeable collimation and focusing optics 24 is bundled on the cylinder surface 116 without it In this case, a lance tube 110 may be required in the bending direction be designed adjustable so as to the deflection angle of the laser beam to be able to change. Incidentally, the construction and operation of this Embodiment the same as in the coating apparatus of FIG. 1.

In the context of the invention, it is also possible, the diode laser directly on Arranging the device head, wherein the laser light guide on the beam side to the diode laser is extended and this in the embodiment of FIG. 2 either co-rotated with the coating lance 104 or fixed to the device head 103 connected and the laser light guide 102 then via a rotary coupling on the laser 101 is connected.

Claims (9)

1. A device for laser coating component inner faces with an, in particular, powdery additional material, comprising a laser source and a device head optically connected thereto, with a coating lance which is mounted thereon via a rotating guide and can be moved over the inner face in a translatory and rotary manner, in which coating lance the laser beam is directed axially from the rotating guide to the tip of the lance and from there to the component inner face, characterised in that the coating lance (4; 104) contains a laser beam-guiding light guide (2; 102) extending from the rotating guide (5; 105) of the device head (3; 103) outside the component inner face (16; 116), continuously over the entire length of the lance to the tip of the lance.
2. A device according to claim 1, characterised in that the laser light guide (102) is rotatably driven together with the coating lance (104), and an optical rotary coupling (23) is provided in the region of the light guide end on the device head side for coupling the laser beam.
3. A device according to claim 2, characterised in that the laser source is arranged on the device head and the laser beam emitted by the laser source is coupled directly into the laser light guide co-rotating with the coating lance.
4. A device for laser coating component inner faces with an, in particular, powdery additional material, comprising a laser source and a device head optically connected thereto, with a coating lance which is mounted thereon via a rotating guide and can be moved over the inner face in a translatory and rotary manner and in which the laser beam is directed axially from the rotating guide to the tip of the lance and from there to the component inner face, characterised in that the coating lance (4) has a rotatably driven outer tube (10) and an inner tube (8) arranged therein and non-rotatably connected to the device head (3), including a laser beam-guiding light guide (2) fixed in the non-rotatable inner tube coaxially to the axis of rotation (A-A) of the outer tube (10) and extending from the rotating guide (5) to the tip of the lance.
5. A device according to claim 4, characterised in that the laser source (1) is arranged remote from the device head (3) and the laser light guide (2) is continuously extended up to the laser source beyond the rotating guide (5).
6. A device according to claim 4 or 5, characterised by channels for coolant and/or (19, 21, 22) for operating medium surrounding the inner tube (8).
7. A device according to any one of the preceding claims, characterised in that the laser source (1; 101) is a diode laser.
8. A device according to any one of the preceding claims, characterised in that optical signals are returned in the laser light guide (2; 102) from the distal light guide end in the opposite direction to the laser beam for process monitoring.
9. A device according to any one of the preceding claims, characterised in that the tip of the lance contains a replaceable optical focusing system (13, 14, 24).

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