Method for producing a metal component

Abstract

Method for machining a metal component which has a three-dimensional shape produced by removing and / or shaping material, wherein one or more superior component sections are electrochemically finish-machined by means of a nozzle-like cathode, via which an electrolyte is delivered into the working region, and wherein the cathode or the metal component is moved freely in space by means of a manipulator element.

Description

[0001]This application claims priority to German Patent Application No. 1020010032701.8 filed Jul. 29, 2010, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The invention relates to a method for machining a metal component which has a three-dimensional shape produced by removing and / or shaping material.[0003]Metal components are machined or shaped using various methods in order to obtain a desired three-dimensional geometry. Material-removing methods such as, for example, drilling, turning, milling, EDM (electrical-discharge machining) and ECM (electrochemical machining) or material-shaping methods such as, for example, stamping, pressing or forging are known. These methods normally serve for rough contouring, i.e. the three-dimensional shape is substantially fashioned by these working processes. Superior component sections, however, still have to be subjected to finish machining in order for any burrs, projections, edges, corners and the ...

AI Technical Summary

Benefits of technology

[0007]The electrochemical working process also enables a wide variety of different materials to be machined, that is to say that even materials which are difficult to machine using conventional working processes, because they are very difficult to cut, can be readily machined by ECM. In conjunction with the freedom of movement of the cathode or of the metal component, that is to say the mobility in any desired manner in space, the method according to the invention therefore offers the possibility of being able to finish-machine any desired components or complex geometries virtually irrespective of the material used.

[0014]In a development of the invention, a gas curtain, preferably an air curtain, laterally enclosing the electrolyte stream at least partly, preferably completely, is blown out via the cathode. That is to say that not only is the electrolyte stream delivered via the cathode but so too is a gas stream, which encloses the electrolyte stream preferably completely. The result of this is that the electrolyte stream is delivered onto the component surface in a concentrated manner and is kept away from the vicinity of the working region by being “blown out”. This avoids the situation where adjacent surfaces are undesirably affected and therefore stray currents lead to undesirable removal in adjacent regions. The nozzle itself is therefore of double-walled design, with an inner electrolyte passage and an outer air passage, which are connected to corresponding supply lines. In addition to air, some other gas, e.g. inert gas such as nitrogen or helium, can also be used for forming the gas curtain.

[0016]A metal component which is in particular preferably to be machined with the method according to the invention is a component of a turbomachine, for example a casing component, but in particular a blade component. Blade components which are especially difficult to machine and have a very complex geometry are integral rotors (“blisks”), guide vane clusters or guide vane rings, as are used, for example, in high-pressure compressors of a gas turbine. Such integral rotors, guide vane clusters or guide vane rings are subject to stringent requirements, for which reason they consist either of a titanium alloy or high-temperature steel, but preferably of a nickel alloy. In particular the guide vane clusters and the guide vane rings have a very complex geometry, normally consisting of two shrouds, between which the twisted guide airfoils extend. The distances between the airfoils go from a few millimeters up into the centimeter range. As a result, the accessibility of the regions between the airfoils is greatly restricted. Nonetheless, in particular the edges / corners or the transition surfaces in these regions require the finish machining according to the invention. If such a guide vane cluster or a guide vane ring is produced from solid material by cutting or other removal processes, this inevitably results in the finish machining, in particular in the region between the airfoils, involving considerable outlay. It is precisely in the production of blade components, in particular of the guide vane clusters or guide vane rings, that the method according to the invention can be used in an especially advantageous manner, in particular if there are very small airfoil and shroud spacings. This is because, with the method according to the invention, the edges and surfaces present there in the region between two airfoils and / or the airfoils themselves can be readily machined, since the very thin, narrow cathode can be moved even into these extremely narrow regions, and positioned there with high precision, via the robot moving it in any desired manner in space.

Problems solved by technology

Whereas this is often straightforwardly possible in the case of large metal components on account of the accessibility of the superior component sections which are to be finish-machined, problems often arise in particular with smaller metal components or with metal components in which the superior component sections are either very narrow or are difficult to reach on account of the component geometry, since the tool can be guided into the desired region only some of the way, if at all.

Further problems are often caused by the material of the metal component.

Whereas components made of titanium alloys still have sufficient machinability and can therefore, for example, be satisfactorily milled, components made of nickel alloys have relatively poor machinability.

In conjunction with complex geometrical relationships, this gives rise to even greater problems in the course of the finish machining.

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