EP3733348B1 - Method and device for smoothing the surface of a workpiece - Google Patents

Description

Technical area

The present invention relates to a method and a device for smoothing a component surface.

State of the art

There are various methods known for smoothing components. Material can be removed, for example, using a geometrically defined or undefined cutting edge. Material removal removes unevenness from the surface, thus smoothing it. In chemical-mechanical polishing, this can be done by a combination of chemical and mechanical effects on the surface of the component. This subject is based on such a method, and in particular it concerns the smoothing of turbomachine or engine components. The document US 5 341 602 A discloses a method and a device on which the preamble of the independent claims is based.

A turbomachine can be functionally divided into a compressor, combustion chamber and turbine. In the case of an aircraft engine, air drawn in is compressed in the compressor and burned in the downstream combustion chamber with added kerosene. The resulting hot gas, a mixture of combustion gas and air, flows through the downstream turbine and is expanded in the process. The turbine and compressor are usually constructed in several stages, with each stage comprising a guide vane and a rotor blade ring. Each blade ring is made up of a plurality of blades arranged in a rotating sequence, around which the compressor or hot gas flows depending on the application. Smoothing these component surfaces can be aerodynamically advantageous, for example.

Description of the invention

The present invention is based on the technical problem of specifying an advantageous method for smoothing a surface of a component.

This is achieved according to the invention with the method according to claim 1. The component is placed in a container (bath) with a liquid-solid mixture, and a relative movement is generated between the mixture and the component. The mixture flows along the surface to be smoothed, which allows a combined chemical-mechanical removal of material to be achieved, and the component is polished chemically and mechanically. According to the invention, a guide surface is provided in the bath or container with the mixture, along which the mixture flows. The guide surface guides the flow and in particular presses the solid component towards the component surface, thus superimposing a directional component towards the component surface.

The guide surface guides the mixture, and in particular the solid portion, onto the surface so that sufficient pressure is achieved there to remove material. The solid portion can, for example, be in the form of particles, in particular spheres, with the balls then rolling along the component surface with sufficient pressure due to the guide to achieve the desired polishing effect. The solid portion in the mixture can, in particular, be so high that a coherent agglomeration of particles or balls is present between the guide surface and the surface of the component; a force chain is thus formed between the guide surface and the component so that the particles/balls are reliably pressed against the component surface. The guide surface can, for example, create or help to set a more uniform pressure across the component surface, which can improve the homogeneity of the smoothing result.

To illustrate: if, for example, you were to put a blade without a guide surface into the mixture and flow around it in a manner similar to the arrangement in the gas channel (inflow at the leading edge and outflow at the trailing edge), the pressure and thus the material removal at the leading edge would be high. Towards the trailing edge it would However, this would decrease, which would result in an overall uneven removal of material. In order to achieve a certain degree of uniformity, the component without a guide plate must then be flowed around in different orientations, for example, which means effort and increases the processing time. With the guide surface, however, the flow can be adjusted so that, ideally, no reorientation of the component is necessary, i.e. uniform material removal is achieved in a single relative arrangement or orientation.

Preferred embodiments of the invention can be found in the dependent claims and the entire disclosure, whereby the presentation of the features does not always distinguish in detail between method and device aspects; in any case, the disclosure is to be read implicitly with regard to all claim categories. If, for example, certain means are described that are used in the method, this is also to be understood as a disclosure of a device equipped with the corresponding means for carrying out the method.

In the context of this disclosure, "a" and "an" are to be read as indefinite articles and thus, unless expressly stated otherwise, always as "at least one" or "at least one". In the bath, for example, several components can be arranged and smoothed at the same time. If the component is an airfoil, this can be part of a single airfoil or a multiple segment; in principle, even a complete airfoil ring can be processed (blisk, blade integrated disk ) .

As already mentioned, the component can preferably be a blade of a turbomachine, which is arranged in the gas channel and has hot gas flowing around it. In principle, an application in the turbine area is also conceivable, i.e. the blade can be arranged in the hot gas channel and hot gas can flow around it. An application in the compressor area is preferred, i.e. the blade can have compressor gas flowing around it in the compressor gas channel. The advantages of the method according to the invention can be particularly evident here, as the homogeneously smoothed component surface can help prevent flow separation, for example.

In a preferred embodiment, the guide surface is a side surface of a guide body around which the bath flows. The latter means that the liquid-solid mixture flows not only along the guide surface, but also along a side surface of the guide body opposite the guide surface. The guide body is preferably made of metal, in particular it can be a guide plate (simple and flexible production).

In a preferred embodiment, the component surface has a curved profile when viewed in a cutting plane and the guide surface is complementarily curved when viewed in the same cutting plane. If the surface is convex, for example, the guide surface extends concavely, and in the case of a concave component surface, it extends convexly. The cutting plane in question is preferably parallel to the direction of flow; in the case of the blade, for example, it can be a tangential cutting plane (in this, the blade profile is viewed, the cutting plane is tangential to a revolution around the longitudinal or rotational axis of the turbomachine).

In a preferred embodiment, the guide surface is arranged in relation to the component surface in such a way that a distance between them decreases in the direction of flow. Specifically, the distance is viewed in section (see the previous paragraph regarding the cutting plane) perpendicular to the streamlines between the surface and the guide surface. Preferably, a distance that decreases continuously (without jumps/steps) in the direction of flow can be used, which can offer advantages with regard to the desired homogenization.

According to the invention, a further guide surface is provided in the bath, which can also be formed by a guide body, in particular a guide plate. The component is or will be arranged between the guide surfaces in a direction perpendicular to the direction of flow. The flow is then guided by one guide surface to a surface area of the component and by the other guide surface to an opposite surface area. In the case of the blade, one guide surface can be assigned to the suction side surface and the other to the pressure side surface.

According to the invention, the guide surfaces between which the component is placed are arranged relative to one another in such a way that a distance between them decreases in the direction of flow. In concrete terms, this guide surface distance is taken in section perpendicular to the streamlines between the guide surfaces, see also the above comments. So, for example, if an airfoil is smoothed and the flow is directed at the leading edge, the distance between the guide surfaces arranged on either side of it decreases from the leading to the trailing edge. Preferably, the distance between the guide surface and the respective surface area (suction or pressure side surface) also decreases, see above.

As an alternative to an airfoil, the component can generally also be a fairing , for example. Channel plates ( panels ) can also be smoothed and thus optimized with regard to the flow around the gas channel. However, the component is preferably an airfoil. To generate the relative movement between the liquid-solid mixture and the component, a nozzle could generally also be provided in the bath, through which the mixture is pumped and thus accelerated onto the component. In this case, the latter would be viewed in a fixed coordinate system, i.e. in the processing machine and therefore also in the assembly or production hall, for example. In a preferred embodiment, the relative movement is achieved by moving the component through the liquid-solid mixture. Viewed in a fixed coordinate system, the component is then moved; it is pulled or pushed through the mixture. In a preferred embodiment, the guide surfaces or guide bodies/guide plates are moved through the bath together with the component. For example, they can be arranged on a holder into which the component is placed and which is then moved through the mixture together with the component.

The liquid-solid mixture can be water-based, for example. Depending on the material of the component, it can contain an acid, e.g. hydrogen peroxide. The liquid component can also contain silicates, for example. The solid component is preferably provided in particle or spherical form, in particular in the form of glass or metal spheres. These can have a diameter in the micro- or millimeter range, for example of at least 200 µm and a maximum of 2 mm, for example of around 0.5 mm.

The invention also relates to a device for smoothing a component surface according to claim 9.

Short description of the drawings

Figur 1

eine Vorrichtung zur Durchführung des erfindungsgemäßen Verfahrens in einer schematischen, teilweise geschnittenen Seitenansicht;

Figur 2a-b

verschiedene Möglichkeiten zur Anordnung von Leitflächen bzw. - körpern zur Strömungsführung in der Vorrichtung gemäß Figur 1;

Figur 3

ein Triebwerk in einem Axialschnitt zur Illustration möglicher Anwendungen.

In the following, the invention is explained in more detail using an exemplary embodiment, whereby the individual features within the scope of the independent claims can also be essential to the invention in other combinations and no distinction is made in detail between the different claim categories. In detail,

Figure 1

a device for carrying out the method according to the invention in a schematic, partially sectioned side view;

Figure 2a-b

various possibilities for the arrangement of guide surfaces or bodies for flow guidance in the device according to Figure 1 ;

Figure 3

an engine in an axial section to illustrate possible applications.

Preferred embodiment of the invention

Fig.1 shows a device 1 for smoothing a component 2, specifically a surface 2.1 of the component 2. The component 2 is a blade or a vane of an aircraft engine, see also Fig.3 for illustration. For smoothing, the component 2 is placed in a container 3 that is filled with a liquid-solid mixture 4.

The component 2 is then moved in the liquid-solid mixture 4, thus generating a relative movement 5 between the liquid-solid mixture 4 and the component 2. This creates a flow 6 of the liquid-solid mixture 4 along the surface 2.1 of the component 2. As the enlarged view illustrates, the mixture 4 is made up of a liquid component 7 (in this case, e.g. water, H ₂ O ₂ , silicates) and spherical solids 8 with a diameter of e.g. 0.5 mm. When the mixture 4 flows along the surface 2.1 due to the relative movement 5, the balls roll off the surface 2.1 with a certain pressure.

In order to achieve a more uniform pressure over the surface 2.1, according to the invention a guide surface 20 is arranged in the mixture 4, which imposes a directional component 21 on the flow 6 towards the surface 2.1 of the component 2. This is shown in the Fig. 2a -c illustrates (especially in Fig. 2a ), each in one cut (based on Fig.1 the cutting plane is perpendicular to the drawing surface and horizontal). In these sections, the profile shape of component 2, e.g. the blade, can be seen.

For the variants according to the Fig. 2a,b A further guide surface 200 is provided, which also imposes a directional component 210 on the flow 6 towards the component surface 2.1. A guide surface 20,200 is thus assigned to both a suction side surface 2.1.1 and a pressure side surface 2.1.2 of the blade. Each of the guide surfaces 20,200 is formed by a guide body 22,220, namely a guide plate around which the mixture 5 flows.

The guide surfaces 20,200 are arranged relative to the component 2 or its surface 2.1 such that a respective distance 25,250 to the surface 2.1 decreases in the flow direction 26. Furthermore, a guide surface distance 27 between the guide surfaces 20,200 also decreases in the flow direction 26.

In the Fig. 2c In the situation shown, the component 2, i.e. the blade, is not flown at its leading edge, but at its trailing edge during smoothing. In this case, only a single guide body 22 with the guide surface 20 is used, which is assigned to the suction side surface 2.1.1 of the component 2. In general, the Fig. 2a-c illustrate different possibilities and options.

Fig.3 shows a turbomachine 30, specifically a turbofan engine, in an axial section (the section plane includes the longitudinal axis 31). Functionally, the turbomachine 30 is divided into a compressor 32, a combustion chamber 33 and a turbine 34, whereby air drawn in is compressed in the compressor 32. In the combustion chamber 33, it is burned with kerosene mixed in, and the resulting hot gas is expanded in the turbine 34. Both the compressor 32 and the turbine 34 are constructed in several stages. The component 2 (the blade smoothed as described above) can be used in both the turbine 34 and the compressor 32, the latter being preferred (due to the high aerodynamic requirements there).

LIST OF REFERENCE SYMBOLS

Component 2 Surface (component surface) 2.1 Suction side surface 2.1.1 Print side area 2.1.2 container 3 Liquid-solid mixture 4 Relative motion 5 flow 6 Liquid component 7 Solids 8th Guide surface 20 Directional component (to the component surface) 21 Guide body 22 Distance 25 Flow direction 26 Guide surface distance 27 Turbomachine 30 Longitudinal axis 31 compressor 32 Combustion chamber 33 turbine 34 Guide surface (other) 200 Directional component (of the further guide surface) 210 Guide body (further) 220 Distance (of the further guide surface) 250

Claims (9)

1. Method for smoothing a surface (2.1) of a component (2) which is designed to be arranged in a gas channel of a turbomachine (30) and which component (2) is preferably an airfoil for a turbomachine (30), the surface (2.1) being a surface (2.1) facing the gas channel, in which method

   - the component (2) is placed in a container (3) with a liquid-solids mixture (4);

   - a relative movement (5) is generated between the liquid-solids mixture (4) and the component (2), i.e. a flow (6) of the liquid-solids mixture (4) along the surface (2.1);

   a guide surface (20) being provided in the liquid-solids mixture (4), along which the liquid-solids mixture (4) flows, a directional component (21) toward the surface (2.1) being imposed on the flow (6), and

   in which a further guide surface (200) is provided in the liquid-solids mixture (4), along which the liquid-solids mixture (4) flows, characterized in that

   the component (2) is arranged between the guide surfaces (20, 200), and in which the guide surfaces (20, 200) are arranged relative to one another such that a guide surface distance (27), which, viewed in a sectional plane, is taken perpendicular to a streamline profile between the guide surfaces (20, 200), decreases in the flow direction (26).
2. Method according to claim 1, in which the guide surface (20) is a lateral surface of a guide body (22) around which the liquid-solids mixture (4) flows, and wherein the liquid-solids mixture (4) therefore also flows along a lateral surface opposite the guide surface (20).
3. Method according to claim 1 or 2, in which the surface (2.1) of the component (2) has a curved profile when viewed in a sectional plane, and the guide surface (20) has a complementarily curved profile when viewed in the same sectional plane.
4. Method according to any of the preceding claims, in which the guide surface (20) is arranged relative to the surface (2.1) such that a distance (25) which, viewed in a sectional plane, is taken perpendicular to a streamline profile between the surface (2.1) and the guide surface (20), decreases in the flow direction (26).
5. Method according to claim 1, in which the surface (2.1) of the component (2) comprises a suction-side surface and a pressure-side surface, wherein both the suction-side surface and the pressure-side surface are each assigned a guide surface (20, 200) in the liquid-solids mixture (4).
6. Method according to any of the preceding claims, in which the component (2) is moved in a stationary coordinate system to generate the relative movement (5), i.e. the component (2) is moved through the liquid-solids mixture (4).
7. Method according to claim 6, in which the guide surface (20) or guide surfaces (20, 200) is or are moved together with the component (2) through the liquid-solids mixture (4).
8. Method according to any of the preceding claims, in which the liquid-solids mixture (4) is water-based with spherical solids (8).
9. Device for smoothing a surface (2.1) of the component (2), for carrying out a method according to any of the preceding claims, characterized in that the device comprises:

   - a container (3) for receiving the liquid-solids mixture (4) and for arranging the component (2);

   - a movement apparatus for generating the relative movement (5) between the liquid-solids mixture (4) and the component (2);

   - a guide surface (20) in the container (3), in order to impose the directional component (21) toward the surface (2.1) on the flow (6), and in which a further guide surface (200) is provided in the liquid-solids mixture (4), along which the liquid-solids mixture (4) flows, for arranging the component (2) between the guide surfaces (20, 200), characterized in that the guide surfaces (20, 200) are arranged relative to one another such that a guide surface distance (27), which, viewed in a sectional plane, is taken perpendicular to a streamline profile between the guide surfaces (20, 200), decreases in the flow direction (26).

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