EP3733348A1 - Method for smoothing the surface of a workpiece - Google Patents

Abstract

The present invention relates to a method for smoothing a surface (2.1) of a component (2), in which method- the component (2) is placed in a liquid-solid mixture (4); - a relative movement (5) between the liquid- Solid-state mixture (4) and the component (2) is generated, that is, a flow (6) of the liquid-solid mixture (4) along the surface (2.1); a guide surface in the liquid-solid mixture (4) (20) is provided, along which the liquid-solid mixture (4) flows, the flow (6) having a directional component (21) being imposed on the surface (2.1).

Description

Technical area

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

State of the art

Various methods are known for smoothing components; material can be removed by machining, for example, with a geometrically determined or indefinite cutting edge. With the material removal, unevenness of the surface is removed, so it is smoothed. With chemical-mechanical polishing, this can be done through a combination of chemical and mechanical effects on the component surface. The present subject matter is directed towards such a method, in particular the smoothing of turbomachine or engine components.

A turbomachine can functionally be divided into a compressor, a combustion chamber and a turbine, whereby in the case of an aircraft engine, the air sucked 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. As a rule, the turbine and the compressor each have a multi-stage structure, with each stage comprising a guide and a rotor blade ring. Each blade ring is made up of a plurality of blades which follow one another around the circumference, around which the compressor or hot gas flows depending on the application. Smoothing these component surfaces can be aerodynamically advantageous, for example.

Presentation 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, with which a combined chemical-mechanical material removal can be achieved, the component is chemically-mechanically polished. 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, pushes the solid body component towards the component surface, so it superimposes a directional component on the component surface.

With the guide surface, the mixture, and thus in particular the solid part, is guided onto the surface, so that there is sufficient pressure for material removal. The solid content can, for. B. particulate, in particular spherical, the balls then roll on the component surface with a sufficiently high pressure due to the guidance to achieve the desired polishing effect. The proportion of solids in the mixture can in particular be so high that a coherent agglomerate of particles or spheres 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, produce or help set a pressure that is more uniform over the component surface, which can improve the homogeneity of the smoothing result.

To illustrate: if, for example, a blade without a guide surface were to be added to the mixture and flow around it in a manner comparable to the arrangement in the gas duct (inflow at the front and outflow at the rear edge), the pressure and thus the material removal at the front edge would be high. Towards the trailing edge he would however, decrease, which would result in an overall uneven removal. In order to achieve a certain leveling of uniformity, the component without a baffle then has to be flowed around in different orientations, for example, which means effort and increases the processing time. With the guide surface, on the other hand, the flow can be adjusted in such a way that, in the ideal case, no reorientation of the component is necessary, that is, a uniform material removal is achieved in a single relative arrangement or orientation.

Preferred refinements of the invention can be found in the dependent claims and the entire disclosure, although a distinction is not always made in detail between process and device aspects when presenting the features; in any case, the disclosure is to be read implicitly with regard to all claim categories. If, for example, certain means are described which 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 therefore always also as “at least one” or “at least one” without expressly specifying the contrary. In the bath, for example, several components can also be arranged and smoothed at the same time. If the component is a blade, this can be part of a single blade or a multiple segment; in principle, a complete blade ring can also be machined (blisk, blade integrated disk ) .

As already mentioned, the component can preferably be a blade of a turbomachine, which is arranged in its gas channel and flowed around it. In principle, an application in the turbine area is also conceivable, i.e. the blade can be arranged in the hot gas duct and hot gas can flow around it. An application in the compressor area is preferred, that is to say that compressor gas flows around the blade in the compressor gas duct. Here, the advantages of the method according to the invention can in particular come into play, namely the homogeneously smoothed component surface can help prevent a flow stall, 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 not only flows 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; it can in particular be a guide plate (simple and flexible manufacture).

In a preferred embodiment, the component surface has a curved profile when viewed in a sectional plane and the guide surface is curved in a complementary manner when viewed in the same sectional plane. If the surface is convex, for example, then the guide surface extends concave, and in the case of a concave component surface it extends convex. Said cutting plane is preferably parallel to the direction of flow, in the case of the airfoil it can be, for example, a tangential cutting plane (in this the airfoil profile is considered, the cutting plane lies tangentially on a revolution around the longitudinal or rotational axis of the turbo machine).

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 considered in the section (cf. the previous paragraph with regard to the section plane) taken perpendicular to the streamlines between the surface and the guide surface. A distance which decreases continuously (without jumps / steps) in the flow direction can be preferred, which can offer advantages with regard to the desired homogenization.

According to a preferred embodiment, 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, based on a direction perpendicular to the direction of flow. The flow is then guided from one guide surface onto a surface area of the component and from the other guide surface onto a surface area opposite thereto. In the case of the airfoil, one guide surface can be assigned to the suction side surface and the other to the pressure side surface.

In a preferred embodiment, 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. Specifically, this guide surface distance is taken in a section perpendicular to the streamlines between the guide surfaces, cf. also the comments above. If, for example, an airfoil is smoothed and, for this purpose, the flow is flowing against the leading edge, the distance between the guide surfaces arranged on both sides thereof decreases from the leading edge to the trailing edge. The distance between the guide surface and the respective surface area (suction or pressure side surface) preferably also decreases, see above.

As an alternative to a blade may be, for example, at the component in general. Also a panel, so act a fairing. 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 considered in a stationary coordinate system, that is to say rest in the processing machine and thus, for example, also in the assembly or production hall.

In a preferred embodiment, however, the relative movement is achieved in that the component is moved through the liquid-solid mixture. Considered in a stationary 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. They can, for example, be arranged on a holder in which the component is placed and which is then moved together with the component through the mixture.

The liquid-solid mixture can be provided on a water basis, for example. Depending on the material of the component, it can, for example, contain an acid, e.g. B. hydrogen peroxide. Furthermore, the liquid component can contain, for example, silicates. The solid component is preferably provided in the form of particles or spheres, in particular in the form of glass or metal balls. These can, for example, have a diameter in the micro- or millimeter range, approximately from at least 200 microns and z. B. at most 2 mm, so for example. Of around 0.5 mm.

The invention also relates to a device for smoothing a component surface. The device has a container into which the liquid-solid mixture can be added or in which it is kept. The component can be placed in the container for smoothing. Furthermore, the device has a movement device by means of which the relative movement between the mixture and the component can be generated, preferably by moving the component. Part of the device can therefore in particular be a holder into which the component can be placed and then pulled through the container. Furthermore, there is a guide surface in the container, in particular a guide body or guide plate. For further details, express reference is made to the above disclosure.

Brief description of the drawings

The invention is explained in more detail below with the aid of an exemplary embodiment, the individual features within the framework of the independent claims also being essential to the invention in other combinations and furthermore no distinction is made between the different claim categories.

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 detail shows

Figure 1

an apparatus for performing 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 FIG 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. In the present case, the component 2 is a blade or a blade of an aircraft engine, cf. also Fig. 3 for illustration. For smoothing, the component 2 is or is placed in a container 3 which is filled with a liquid-solid mixture 4.

The component 2 is then moved in the liquid-solid mixture 4, so a relative movement 5 is generated 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 composed of a liquid component 7 (in the present case, for example, water, H ₂ O ₂ , silicates) and spherical solids 8 with a diameter of, for example. B. 0.5 mm built. When the mixture 4 flows along the surface 2.1 due to the relative movement 5, the balls roll with a certain pressure on the surface 2.1.

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 in the Fig. 2a -c illustrates (specifically in Fig. 2a ), each in one section (based on Fig. 1 the cutting plane is perpendicular to the drawing surface and horizontal). In these sections, the profile shape of the component 2, so z. B. the blade to recognize.

With the variants according to Fig. 2a, b a further guide surface 200 is provided in each case, 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 airfoil. Each of the guide surfaces 20, 200 is in each case 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 in such a way that a respective distance 25, 250 from 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 in Figure 2c In the situation shown, the component 2, that is to say the airfoil, is not exposed to the flow at its front edge but at its rear edge during smoothing. In addition, 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. Generally, the Figures 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). The turbo machine 30 is functionally divided into a compressor 32, a combustion chamber 33 and a turbine 34, with air sucked in in the compressor 32 being compressed. In the combustion chamber 33, it is burned with kerosene mixed in, and the hot gas produced is expanded in the turbine 34. Both the compressor 32 and the turbine 34 are each constructed in multiple stages. The component 2 (the blade blade smoothed according to the description above) can be used both in the turbine 34 and in the compressor 32; the latter is preferred (because of the high aerodynamic requirements there). <b> REFERENCE CHARACTERISTICS LIST </b> Component 2 Surface (component surface) 2.1 Suction side surface 2.1.1 Print face 2.1.2 container 3 Liquid-solid mixture 4th Relative movement 5 flow 6th Liquid component 7th Solid 8th Guide surface 20th Directional component (to the component surface) 21st Guide body 22nd distance 25th Direction of flow 26th Baffle spacing 27 Turbo machine 30th Longitudinal axis 31 compressor 32 Combustion chamber 33 turbine 34 Guide surface (more) 200 Directional component (of the further guide surface) 210 Guide body (further) 220 Distance (of further guide surface) 250

Claims (13)

Method for smoothing a surface (2.1) of a component (2), in which method - The component (2) is placed in a liquid-solid mixture (4); - A relative movement (5) is generated between the liquid-solid mixture (4) and the component (2), that is to say a flow (6) of the liquid-solid mixture (4) along the surface (2.1);
wherein a guide surface (20) is provided in the liquid-solid mixture (4), along which the liquid-solid mixture (4) flows, the flow (6) having a directional component (21) towards the surface (2.1) is imposed. Method according to Claim 1, in which the guide surface (20) is a side surface of a guide body (22) around which the liquid-solid mixture (4) flows, in which the liquid-solid mixture (4) also flows along a the guide surface (20) opposite side surface flows. 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) when viewed in the same sectional plane has a complementary curved course. Method according to one of the preceding claims, in which the guide surface (20) is arranged relative to the surface (2.1) in such a way that a distance (25) which, viewed in a sectional plane, is perpendicular to a streamline profile between the surface (2.1) and the guide surface (20) is taken, decreases in the flow direction (26). Method according to one of the preceding claims, in which a further guide surface (200) is provided in the liquid-solid mixture (4), along which the liquid-solid mixture (4) flows, the component (2) between the guide surfaces (20,200) is arranged. Method according to Claim 5, in which the guide surfaces (20,200) are arranged relative to one another in such a way that a guide surface distance (27), which, viewed in a sectional plane, is perpendicular to a streamline profile between the guide surfaces (20,200), in the flow direction (26) decreases. Method according to one of the preceding claims, in which the component (2) is designed to be arranged in a gas duct of a turbomachine (30), the surface (2.1) being a surface (2.1) facing the gas duct. Method according to Claim 7, in which the component (2) is an airfoil for the turbomachine (30). Method according to Claim 8 in conjunction with Claim 5 or 6, in which the surface (2.1) of the component (2) comprises a suction side surface and a pressure side surface, both the suction side surface and the pressure side surface each having a guide surface (20, 200) in the solid liquid Mixture (4) is assigned. Method according to one of the preceding claims, in which the component (2) is moved in a fixed coordinate system to generate the relative movement (5), that is to say the component (2) is moved through the liquid-solid mixture (4). Method according to Claim 10, in which the guide surface (20) or guide surfaces (20,200) is or are moved together with the component (2) through the liquid-solid mixture (4). Method according to one of the preceding claims, in which the water-based liquid-solid mixture (4) is provided with spherical solids (8). Device for smoothing a surface (2.1) of the component (2), that is to say for carrying out a method according to one of the preceding claims, which device has: - A container (3) for receiving the liquid-solid mixture (4) and for arranging the component (2); - A movement device for generating the relative movement (5) between the liquid-solid mixture (4) and the component (2); - A guide surface (20) in the container (3) in order to impose the directional component (21) on the flow (6) towards the surface (2.1).

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