Apparatus for supplying powder filler materials in a welding zone.

p0001The invention relates to a device for feeding powdered filler materials by a standing under the action of a conveying gas conveyor pipe in the area of ​​a welding point located in the effective area of ​​a welding unit, wherein the conveying pipe is formed in a straight line in the vicinity of the weld and inclined there with respect to the axis of action of the welding unit runs ,

p0002From EP-B 1-0173654 a device of the mentioned type is known, which formed as a laser welding unit unit produces a directed onto the weld beam. The effective axis formed by the longitudinal axis of the laser beam can be arranged vertically or inclined to the welding point, the feed of the powdered filler materials carried out in such a way that the area to be heated surface area is exposed by the falling powder therethrough; possibly the detected by the laser beam surface area is greater than the lying in this deposit range of additional materials. However, at issue prior publication contains no indication has what dimension of the laser beam and the manner in which the targeted deposition of the filler metal is brought about within the area covered by the laser beam surface area.

p0003The invention has for its object to provide a supply of powdered filler materials, which makes it possible to weld especially thin-walled workpieces with wall thicknesses in the millimeter range and with in connection therewith thin seam joints with the best possible utilization of the supplied additional materials: It is a possible large proportion of filler materials are detected by the laser beam and used to form the weld. The invention will come especially in laser welding for use; However, it should also be usable in TIG, MIG / MAG and plasma welding.

p0004This object is achieved by a device having the features of claim 1. The invention is based on based on the idea to achieve by appropriate design of the feed for the additional materials with respect to the weld an accuracy which lies in the millimeter range. This can be achieved, in particular, that the inner surface of the end portion of the feed pipe is designed to be particularly smooth for the filler materials, ie, having compared to the average grain size of the filler metals small roughness that the length of said end portion of at least fifty times the size of its inside diameter accounts and this is greater at least by a factor of 3 than the present in the consumables largest grain size. The operation of the feed device can in this case optionally further improved in that the length of the (particularly smoothly formed) end area at least constitutes the hundred times the size of its inside diameter.

p0005The required low roughness of the inner surface of the delivery pipe should be at most on the order of a few micrometers. Preferably, the inner surface of the end portion is polished (claim 2); their roughness lies below about 0.4 microns. The guiding accuracy can be improved by suitable dimensioning of the grain size of the filler material in relation to the inner diameter of the end portion on. The filler materials should thereby be such that the internal diameter of the end portion at least by a factor of 5 (preferably at least by a factor of 5 to 10) is larger than the largest particle size (claim 3).

p0006Thus the conveying tube retains the desired low-guiding properties over a longer period of operation, its end should at least consist of a particularly wear-resistant material; as suitable material comes in particular ceramic in question (claim 4).

p0007Depending in particular on the inner diameter of the conveyor tube and on the size of the weld, the distance between the latter and the outlet cross section of the conveyor tube should be at most 20 mm - preferably at most 15 mm - amount (claim 5).

p0008The subject invention can thus be advantageously embodied in that at least in the end region of the conveyor tube, an electrostatic field is present and through it moving consumables a similar electrostatic charge (claim 6). Such a configuration results in a forward direction to the tube axis repulsion of the filler materials within the conveying tube. In this way, the degree of unwanted transverse movements within the production tubing can decrease with the result that the exiting this flow has a greater accuracy.

p0009If ferromagnetic filler materials are used, the end portion of the feed pipe is equipped at least on part of its longitudinal extension with a magnet unit, by means of whose magnetic field acting on the filler metals latter in the direction of the longitudinal extension of the end portion can be aligned (claim 7); the magnet unit should then extend at least to the vicinity of the production pipe outlet section. Preferably, the magnet unit consists of an end portion surrounding the electromagnet (claim 8); This can - be designed in such a way that it produces a permanent, pulsating or alternating magnetic field whose axis is oriented parallel to the conveyor pipe - depending on the operating conditions. Under the influence of the magnetic field generated by the magnet unit can be the consumables align thready and thus de concentrated r weld and perform with high accuracy. By suitable adjustment of the magnet unit in particular to the configuration of the feed pipe and the characteristics of the filler materials (ie, through appropriate dimensioning of the effective inside the conveyor tube magnetic field), the accuracy can be improved if necessary such an extent that the distance between the outlet cross section of the conveyor tube and the weld significantly may be greater than indicated above (see claim. 5); depending on the other operating conditions of the distance can also assume values ​​above 40 to 50 mm.

p0010The guiding properties of the feed pipe can be possibly improved by the fact that at least one of the straight part of the end of preceding section of the conveyor tube has a continuous, uniform orientation of filler materials supporting curvature (claim 9). This causes that create the additional materials under the effect of centrifugal force to the relative center of curvature outside of the inner surface and thereby unwanted transverse movements are difficult within the production tubing. The previously mentioned conveying pipe section expediently has such a curvature that has a radial acceleration of filler materials between 1 to 20 g result (claim 10). The embodiment according to claim 9 and / or 10 has the mentioned advantageous properties particularly when it cooperates with a magnet unit (claim 7 and / or 8). Optionally, the guide feature of the conveying pipe can, however, already improved by the fact that the conveyor pipe section in question - is curved in the manner mentioned - without the influence of a magnetic field.

p0011A further development of the subject invention is characterized in that the end region of the conveying pipe is surrounded at least over part of its longitudinal extent by a gas supply tube (claim 11). The gas feed tube allows the weld to influence the welding process (example: limiting the formation of plasma welding) to apply a working gas. In arc welding, the gas supply pipe to the generation of a protective gas cushion serves; the conveying gas should in this case have the same composition as the shielding gas.

p0012The invention is illustrated below with reference to the drawings, exemplary embodiments in detail. Show it:<dl id="dl0001"><dt>Fig. 1A</dt><dd>schematically, partly in section the construction of a feeder,</dd><dt>Fig. 1B</dt><dd>a partial view along the line Ia-Ia in Fig. 1a, </dd><dt>FIG. 1c, d</dt><dd>enlarged view of a section along the line Ic-Ic or Id-Id in Fig. 1a,</dd><dt>FIG. 2</dt><dd>a partial section in the region of the weld through the end region of a conveying pipe which is surrounded by a gas supply tube,</dd><dt>Fig. 3</dt><dd>a partial view of the straight end portion of a conveyor tube which is provided on a part of its longitudinal extension with a magnet unit,</dd><dt>FIG. 4a</dt><dd>schematically a partial view of a feeding device, which is employed in TIG welding,</dd><dt>FIG. 4b, c</dt><dd>enlarged position a section along line IVb-IVb and IVc-IVc in Fig. 4a,</dd><dt>Fig. 5</dt><dd>a representation of the shape of the delivery flow which forms the outlet of a ceramic tube with a commercially available surface roughness,</dd><dt>Fig. 6</dt><dd>in relation to FIG. 5 on an enlarged scale, the formation of a feed stream which forms the outlet of a ceramic tube with smooth inner surface,</dd><dt>Fig. 7</dt><dd>in relation to FIG. 5 on an enlarged scale, the formation of a substantially filiform feed stream which can be produced by means of acting on ferromagnetic filler materials magnetic.</dd></dl>

p0013. The arrangement shown in Figure 1a and b, by means of the thin metal plates 1 and 2 can be welded together, has the following main components: A laser unit 3, a metering unit 4 for powdery fillers 5, a device connected to a working gas source 6 gas supply pipe 7 and a conveyor pipe 8, via which the dosing of 4 taken fillers 5 the area of ​​the weld 9 can be fed. The laser unit 3 is composed of the actual laser 10, the laser beam guide tube 11, the working head 12 and the welding adapter. 13 The exiting laser beam 10 from the laser 10a is in the working head arranged deflection body 12a, 12b is deflected and focused on the welding point 9; the axis 10b of the laser beam exiting the weld adapter is oriented perpendicular to the metal sheets 1 and 2 plane. The metering unit 4 comprises a sealed housing 15 with a cover 14, whose interior can be acted upon 15a via a conveying gas source 16 via a conduit 17 with conveyor gas (for example helium). Within the housing 15, a metering wheel 18 is rotatably supported about a fixed axis 18a, which can be moved by a drive, not shown in a counterclockwise direction. The annular groove 18b formed as a middle area of ​​the dosing wheel is located below the outlet opening 19a of a filled with the powdered filler materials hopper 19. After switching off the conveying gas source 16 and open the lid 14 may be the filling of the hopper 19 complements. The front portion 8a of the conveyor tube projects to form a sealing point 20 into the housing 4, and ends - as seen in the circumferential direction of the Dosierrrades 18 - behind the hopper 19 in the vicinity of the annular groove 18b. In the present embodiment, the front portion 8a is arranged perpendicular to the funnel axis 19b; However, it may be inclined with respect to an imaginary horizontal and downward.

p0014The the weld 9 facing end portion 8b of the conveyor tube is formed straight and - as well as the gas supply pipe 7 - mounted on a bracket 21 on the side of working head 12th The inclination of the end portion 8b (it extends with respect to the laser beam axis 10b at an acute angle) is chosen such that the leakage cross section 8c leaving flow 5a is incident in the laser beam axis 10b on the weld 9 and is melted there to form a weld 22nd During the welding process, the area of ​​the weld 9 is also acted upon to limit the plasma welding and / or for shielding against the environment via the gas supply pipe 7 with helium.

p0015The basic idea of ​​the invention is in accordance with the length of the ceramic (Al₂O₃) existing end portion 8b, which has an inner diameter of 0.6 mm, 50 mm.

p0016When a particle size of the feed additive materials aged 40 to 64 micrometers of said inner diameter by about a factor of 10 larger than the existing largest grain size. The smoothed by polishing inner surface of the end portion has a roughness that is small compared to the average grain size of the filler materials; even the smallest particle diameter are a factor of 100 greater than the surface roughness after polishing present 8b (in the order of 0.4 microns) of the inner surface of the end portion.

p0017The Figures 1c and 1d show the location of the prepared for welding thin metal sheets 1, 2, or the compound prepared by the weld seam 22 between the metal sheets. The measures outlined above, the coming out of the conveyor pipe 8 Flow lets 5a focus extent that its diameter increases only slightly on the way to the welding point 9; In this case, the distance of the outlet cross-section 8c should not be greater than 20 mm from the weld point 9 where possible.

p0018In deviation 1a of the embodiment shown in FIG., the subject invention also be constructed in such a way that the end portion 8b of the conveyor tube 8 (the inner diameter d and the smoothly formed inner surface 8d) at least enclosed over part of its longitudinal extension of a gas supply pipe 23 ( Fig 2). which the weld 9 facing the outlet aperture 23a is located in the illustrated embodiment, the welding location 8c is slightly closer than the outlet cross section. The light emerging from the gas supply pipe 23 Inert gas expediently has the same composition as the feed gas for the additional materials. Where possible, the inclination angle between the laser beam axis 10b and the end portion 8b should as small as possible, be so acute.

p0019If the weld fed filler metals are ferromagnetic, the achievable means of the conveyor tube accuracy can further improved in that the end portion 8b is provided on a portion of its length with an electromagnet 30 (Fig. 3). This is such that the magnetic field emanating from it in the interior of the end portion 8b parallel to its longitudinal extension extending magnetic lines.

p0020Under the influence of this magnetic field can be the filler materials in the field of conveyor tube axis focus 8e, so that the amount is reduced to transverse movements and friction processes within the end portion 8b. The legislation at issue embodiment makes it possible to let the filler materials emerge as a filamentary flow 5a toward the welding site substantially. The electromagnet 30 may, if necessary, be designed such that it produces a permanent, pulsating or alternating magnetic field. The achievable by means of the feed pipe 8 accuracy can be in the present embodiment (Fig. 3) optionally further improved by that other than as shown in FIG. 1 a - the front portion 8a to form a continuous steady curvature (ie shown without the loop) merges into the end portion 8b. Such a configuration of the feed pipe 8 with the result that the entering into the front portion 8a additive materials come under the action of engaging you centrifugal force on the part of the inner surface for bearing, which is located with respect to the center of curvature outside, and are in this case oriented uniform within the conveying tube. The transition of the inner surface of the curved conveyor tube section to that of the straight line portion of the end portion should likewise be designed to be particularly smooth and without neck.

p0021Figures 4a-c show a different design and applicability of the subject invention. The correspondingly designed conveyor tube with the straight end portion 8b is associated with a welding unit 3, by which the tungsten inert gas welding (TIG) is executable. The welding unit is in a known manner of a housing 24 and a itself. Downwardly subsequent welding adapter 25, in which a tungsten electrode 26 is held vertically adjustable can be supplied through the interior space 25a of the welding adapter during welding the weld a shielding inert gas (for example argon or helium). The coming out of the end portion 8b flow 5a of additional materials is melted by the formed between the tungsten electrode 26 and the weld 9 arc to form a weld 27th Figs. 4b and 4c show the sheets to be joined 28, 29 prior to performing or after completion of the welding operation.

p0022In what way can the accuracy improve in feeding powdered filler materials, is described below with reference to FIGS 5 to 7. these give the result of specific experiments again.

p0023Fig. 5 shows the configuration of a conveying stream which exits from a ceramic conveyor pipe with commercially available roughness, among other process conditions: Grain size of the powdered filler metals: 40 to 63 microns; spattered Mass flow exiting the additional materials: about 6.5 g / min. Conveying gas: argon; 0.4 l / min. = 24 m / sec. Conveying speed of the filler materials: 3.3 to 4.2 m / sec. Inner diameter of the conveying pipe: 0.6 mm.

p0024Under the experimental conditions mentioned above, the exiting from the feed tube flow extended to additional materials in such a way that it already has a diameter of about 4 mm at a distance of 10 mm. The detected by the flow end surface at 10 mm distance is more than four times as large as the outlet cross-section of the conveyor tube.

p0025Fig. 6 shows that the diameter of the exiting flow rate - starting in turn from an inner diameter of 0.6 mm of the feed pipe - at a distance of 10 mm only increased to 0.8 mm, if the inner surface of the existing ceramic conveying tube by polishing is smoothed. The other experimental conditions are: Grain diameter of the supplied additional materials: 40 to 63 microns, spattered Mass flow of the filler metal: about 12 g / min. Conveying gas: argon; 0.5 l / min. = 30 m / sec. Conveying speed of the consumables: 14.2 to 17.0 m / sec.

p0026The accuracy can be therefore greatly improve if the inner surface of the feed tube has a surface roughness which is small compared to the mean particle size of the feed additive materials. With a surface roughness of 0.4 microns and a (smallest) particle size of 40 microns, the resultant ratio (roughness / particle size) l / 100th The final cross-section of the flow is only a factor 1.8 larger than the inner diameter of the delivery tube.

p0027Fig. 7 shows that by the action of a suitable magnetic field (see to Fig. 3.) Can produce a substantially filamentary flow ferromagnetic filler materials; serving as a guide member delivery tube is as explained with reference to FIG. 6 is formed. Other experimental conditions: Particle size of the feed additive materials: 40 to 63 microns, spattered Mass flow of additional materials: Approximately 12 g / min. Conveying gas: argon; 0.5 1 / min. = 30 m / sec. Conveying speed of the individual particles or fibers of the filler materials: from 17.5 to 18.2 and from 13.2 to 14.0 m / sec.

p0028Due to the substantially filamentary training emerging from the conveyor tube flow rate may be at a distance of 10 mm no change in the area occupied by the additional materials section notice. The mentioned embodiment of the subject invention thus makes it possible accurately deliver a small-area weld ferromagnetic filler metals and thus substantially fully taken into account in the formation of the weld.

p0029The advantage achieved with the invention is particularly to be seen in that even relatively thin-walled articles can be welded in cases where appropriately sized welding wires are not available, draw an increased cost to themselves and / or can not be processed with the required accuracy , In contrast, no difficulty the preparation and use of powdered filler materials for use in small-area welds.