HK1203062B - Device for recontouring a gas turbine blade - Google Patents

Description

The invention relates to a device for reconstructing a gas turbine blades with the characteristics of the general concept of claim 1.

The blades in gas turbines, especially in aircraft engines, are subject to wear and tear in operation caused by erosive particles, such as sand or dust.

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As a consequence of such a deterioration in the aerodynamic profile, the gas turbine loses efficiency, i.e. the gas turbine needs more fuel for the same performance.

It is therefore economically desirable to prevent the wear of compressor blades, in particular the deterioration of aerodynamically optimized blades.

To this end, repair procedures have been established to restore damaged compressor blades to the most aerodynamically optimal geometry.

A device is known from US 6.302.625 B1 which allows the edge of the shovel to be reconfigured and is guided to the shovel in a predetermined orientation by means of various positioners during the reconfiguration process.

The positioners provide a kind of forced guide for the device to the shovel, so that the device can be easily handled by placing it on the shovel edge and moving it along the shovel edge.

The positioners are placed in a lateral surface of a tapering tapering slot, which is used to raise the device to one of the edges of the shovel. When the device is suspended on the shovel edge, the positioners reach the device laterally at one of the shovel surfaces. The depth of the device's rise to the shovel edge is limited by the conicity and depth of the gap of the device. The actual section of the device that changes the shape of the shovel is located at the bottom of the gap.

The conical cleft thus forms a guide for the device, the depth at which the device is placed on the shovel being dependent on the individual handling of the device. Furthermore, since the reconfiguration of the shovel in this device is carried out by surface treatment, it is necessary that a certain minimum distance of the shovel edge from the bottom of the cleft is available to form a cavity into which excess material can be absorbed.

In addition, some gas turbine blades, such as new fan blades, have geometrically complex edge geometries which make it difficult to precisely work the edges of the blades with known devices.

For example, in certain fan blades, the upper part of the blade operates in the supersonic range and the lower part in the subsonic range during operation.

In addition, the basic material is always removed from the gas turbine blades by a commonly used spanning process, thus shortening the length of the blades by the reconfiguration process.

The purpose of the invention is therefore to create a device for reconstructing a gas turbine blades in which the above problems can be reduced or avoided.

To solve the problem, a device is proposed for reconfiguring a gas turbine blades, with:at least one support which is designed to lie on one edge of the gas turbine blades during reconfiguration,at least one side bearing designed to lie on the suction and/or pressure side of the gas turbine blades in a lateral direction during reconfiguration,a machining unit which is used to process the gas turbine blades, The machining unit is designed to melt at least part of the edge using a beam of energy in such a way that the material solidifies into a new shape without adding any additional material.

The particular advantage of the proposed guide is that the machining unit is guided along the edge to be machined, so that the machining unit intended for the machine is guided at a constant distance to the edge or in a constant orientation to the edge, and the machine is thus able to follow the course of the edge.

The device can also be used on geometrically very complex blades, in particular on different types of gas turbine blades.

The quality of the contouring is improved by the fact that the machining unit is designed to melt at least a part of the edge by means of an energy beam in such a way that the material essentially solidifies into a new contour without the addition of additional material.

A device designed for such processing of the blade edge by means of an energy beam essentially without the addition of additional material differs significantly from the known devices. A particular advantage of the device is that no material loss is caused by splitting processes (e.g. grinding processes) during the reconfiguration.

In addition, an advantage of such a device is that the length of the gas turbine blades (also called chord length) is not further reduced by machining with the device, but can even be partially reconstructed, as described below.

According to the invention, the material is essentially solidified by machining with the device without adding additional material to a given contour. The specifications mean that the melting of the material and the subsequent geometry change are not random, but that the device allows to create a specific shape or geometry similar to the original contour of the new part, which is advantageous, for example, in terms of its aerodynamic properties.

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Preferably very small quantities of additives can be introduced into the area melted by the energy beam. Although the characteristic of the processing is that it is essentially possible to do without the addition of additional material, very small quantities (less than 50% of the melted volume) of additives can be introduced into the melt zone, e.g. to achieve a particularly hard, erosion resistant or otherwise advantageous entry edge.

In addition to reconfiguration essentially without adding additional material, the device may be configured in a preferred embodiment to reconfigure the shovel edge in a custom welding process with the addition of additional material.

The machining unit may preferably also include elements, such as mirrors, through which the laser beam can be swung back and forth in a lateral direction to keep the laser beam always pointed at the edge.

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The device preferably includes a handheld device, in which the machining unit is located and which is passed through the upper and side bearings along the edge, and a laser unit connected to the handheld device, in which a laser is generated and then transmitted to the machining unit.

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The machine may be used as an alternative or in addition to the previously described machine without spanner, preferably including means of spanner, for example, the machine may be interchangeable and the device may be used for spanner or spanner reconfiguration by choice.

Similar to the spanning process, the component can be improved in terms of its aerodynamic properties by a spanning device or machining unit.

The new contour described above, by means of a non-spanning machining, usually gives the shovel even better aerodynamic properties than a spanning machining.

The guidance of the device can be improved by a number of other features.

For example, the device should preferably have at least two bearings and at least two side bearings, which can increase the stability and reliability of the device.

Preferably the machining unit is placed between the bearings, which is beneficial for machining precision, as it provides better protection against any tilting in the direction of machining.

Preferably, the side bearings shall each have at least two attachment points and/or attachment surfaces. Depending on whether the side bearing includes, for example, rotating elements, the side bearings may be in contact with the shovel through surfaces or points. The side bearings guide the device so that the machining element can always be used precisely.

This guidance can preferably be improved by placing the attachment points and/or the attachment surfaces of at least one side bearing in a plane of contact with the attachment point or the attachment surface of a bearing. This contact plane is preferably perpendicular to the direction of machining, as described in detail in Figures 2 to 5 below. The advantage of such an arrangement is that it allows for more precise guidance of the device compared to known devices.

This can be further improved by providing a second contact plane at which the attachment points of side and tread bearings are also in a plane which is in turn preferably perpendicular to the direction of machining.

In order to avoid abrasion and/or scratches on the gas turbine blades, one or more of the bearings and/or side bearings should preferably be formed by rotating bearings.

To improve the attachment of the device to the gas turbine blades, one or more pressing devices shall preferably be provided on the suction and/or pressure side of the gas turbine blades opposite the side bearings. Preferably, at least one pressing device shall be provided. The force shall preferably be applied by movable rollers or bands which, by means of pneumatic pressure stamps and/or spring elements, generate the pressure forces independently of the thickness of the gas turbine blades. Accordingly, at least one pressing device preferably comprising pneumatic, hydraulic and/or spring elements.

The pressing device enables the apparatus to attach itself to the shovel by means of a clamping force, so that the apparatus does not detach from the shovel or move unintentionally relative to the shovel, even under the reaction forces exerted by the machining unit during the machining operation.

Preferably, the pressing device includes rotatable rollers, which can be used to achieve a much more uniform movement, which allows very low and uniform speed of movement, especially when the edge is continuously reconfigured.

In this case, it is advantageous to have at least one roll drivable by means of a drive, which allows the device to be moved along the edge of the shovel, with controls allowing particularly smooth and small forward movements.

It is further proposed that the drive and the machining unit are controllable in pairs. Insofar as the machining unit reconfigures the edge, e.g. by melting, welding or even by spinning, the speed of the device has at least an indirect influence on the shape accuracy of the reconfigured edge, so that this relationship can be taken into account by a coupled control of the drive and the machining unit. For example, the machining unit can be automatically switched off when a final stop of the board or a shutdown of the device is reached, or the machining intensity can be increased with a fast run.

It is also proposed that the rollers be coated with an elastomer, which will at least slightly elasticise the surface of the rollers, so that small bumps on the surface of the shovel can be compensated and elastic clamping forces can be more easily applied to the shovel without the device itself having to be particularly elastic.

In another preferred embodiment, at least one of the bearings comprises two rollers connected by a rotating bearing axis, and machining takes place between the two rollers, thus allowing the machining plane to coincide with a contact plane.

Preferably the machining unit is moved in one direction perpendicular to the machining direction.

The characteristic perpendicular to the direction of machining includes all directions which run transversely to the direction of machining. Two directions are preferred: on the one hand, the lateral direction in which the side bearings are also on the gas turbine blades, and the vertical direction, which is perpendicular to both the direction of machining and the lateral direction.

The movement of the edge is made perpendicular to the direction of machining, which allows the machining unit to follow the edge particularly well, both lateral irregularities and deviations in the vertical direction.

The invention is explained below by means of preferred embodiments, with reference to the accompanying figures, showing: Fig. 1:a device for reconfiguration at the edge of a shovel;Fig. 2:a side view of the machining unit positioned on the edge of a shovel;Fig. 3:a cross-sectional view of the machining unit positioned on a gas turbine shovel with a role to compensate for cracks in the gas turbine shovel;Fig. 4:a representation of the preferred double three-point storage of the device;Fig. 5:a representation of the forces acting on the shovel;Fig. 6:a mixed side and side view of the device positioned on a shovel edge;Fig. 7:a cross-sectional view of the machine positioned on a gas turbine shovel;Fig. 8:a representation of the shape of the machine by introducing a straight line and a straight line;Fig. 9:a representation of the shape of the machine after the installation of a rear axle and a straight line.

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The blades 2 have two edges 3a each, an inlet and an outlet edge.

Figure 1 also shows the processing level 12 described in detail later, and the two management and contact levels 13 and 14.

Figure 2 shows a side view of machining unit 4 which is part of the apparatus 1 and is positioned on a shovel edge 3a. The machining unit 4 is moved along with the apparatus 1 along a machining direction 8 along the edge 3a. In this representation the housing of the apparatus 1 and other apparatus parts have been omitted for the sake of the overview.

During the machining movement, machining unit 4 reconfigures edge 3a, which in this example is the flow-entry edge of the blade 2.

The machine can be moved in the direction of the image plane via the shift axis 9 and this movement is further illustrated in Figure 2.

In Figure 3 a cutting view is shown by the machining unit 4 on a blade 2 also shown in the cut.

In this example, the device 1 comprises an axial displacement unit 23 connected to the machining unit 4 by means of a shift axis 9 which allows the lateral displacement of the machining unit 4.

Furthermore, in this embodiment, the fitment unit 23 comprises an elastomer coated roll 11 located on the side of the blade, in this case the printing side 3c, to guide the fitment unit 23 or the machining unit 4 connected to the fitment unit 23.

The machining unit 4 is offset in the lateral direction 7. This lateral direction 7 runs transversely to the machining direction 8. It also runs tangentially to edge 3a in this example.

The direction of movement of the machine 1 is defined by the direction of movement of the machine 1 (for example, the direction can be defined by two points (start and end of the machine) connected by a line (the direction of operation 8). This line is not the same as the edge of the machine, which has curves or rounded lines, especially in complex shafts.

Figures 4 and 5 show the preferred double three-point bearing of the device. 1 A three-point bearing always comprises a side bearing 5a or 5b, each of which is in contact with a side surface of the blade 2 via two attachment points 22 and a support 6a or 6b, each of which is mounted on the edge of the blade 3a via an attachment point 22.

In this embodiment, a three-point bearing is formed by the bearing 6a and the side bearing 5a, wherein the bearing 6a comprises the guide point AB3 and the side bearing 5a comprises the guide points AB1 and AB2.

The second three-point bearing is formed by the bearing 6b and the side bearing 5b, the bearing 6b comprising the guide point AB3' and the side bearing 6a comprising the guide points AB1' and AB2'.

The machining unit 4 is located between the three-point bearings.

The pressure and the forces resulting from the movement of the device are supported by the pressure F3, which is preferably located on the opposite side of the blade 2. It is preferably located in an area which is centrally located between the three-point bearings. Alternatively, several pressure forces can be used, the resulting pressure being approximately equivalent to the pressure F3.

In Figure 3, the left reel 11 (on the suction side 3b of the shovel 2) is shown as an androller, the right reel 11 (on the pressure side 3c of the shovel 2) as a guide reel. The guide reel is used to shift the machining process, for example when a gap in the shovel 2 between the two openings 6nn and 6n is used. It follows the sliding reel 2 and the reel 2 is used for the actual processing, and the pushing reel uses at least part of the pressure.

The F3 force is preferably provided by a non-shown pressure device, preferably pneumatically operated, or by lever-driven clutches, hydraulics, spindles or linear motors.

For the operation or removal of the device 1, the pressurised device or force F3 shall be reversed, preferably in operation, following the changing thickness of the components by force control.

If necessary, the adjustment unit 23 of machining unit 4 shall preferably be able to compensate for slight deviations and minor damage at the level of machining.

Figures 6 and 7 illustrate the geometrical boundary conditions. The upper part of the figures is a side view and the lower part a top view. The device 1 is guided along the shovel 2 by means of two three-point bearings, each in a contact plane 13, 14.

The total distance Z of the contact planes 13, 14 is X + Y. For example, if a gap within the blade edge causes a deviation, then it hits the working plane 12 with the distance X. This measurement deviation does not exist when X = 0. Very small deviations are achieved when X is minimal and Y is maximum.

In the example shown in Figure 6, a reel 11 allows the machining unit 4 to be precisely moved along the edge 3a, since the machining unit 4 can be moved laterally, if necessary, by this tracking reel to accommodate deviations in the edge flow.

Another embodiment is shown in Figure 7 where the value of X is reduced to zero, again to achieve maximum axial adjustment accuracy by the device 1.

Reducing the value of X to zero continues to provide the technical advantage of maximising the tangential angle to the flow area, with the two guide points AB1 and AB2 providing the tangential angle.

The problem which may arise in this case, namely that the positioning position and the machining function may be in the same place, can be solved by replacing the bearing 6a or the guide point AB3 by a pair of rollers (26).

The rotating axis allows measurement accuracies, roughness and height differences to be measured before and after machining, thus avoiding the need for an additional reel 11 for tracking (as shown in Figure 6).

The machining unit 4 may include a splice-off or grinding operation of the edge 3a. Alternatively, a material order by a welding order or a transformation of the edge 3a by a melting of the edge 3a is also possible, as for example disclosed in the DE 10 2010 036 042 submitted by the applicant.

The preferred melting of edge 3a is illustrated by example in Figure 8.

The edge 3a is shown in Figure 8 as enlarged, and its state before repair by device 1 is shown as erosion contour 17. The erosion contour 17 is usually roughly planar and has a front surface. The state of edge 3a after repair is shown as new contour 18 or span contour 27. The device, which preferably includes a laser unit to generate a laser beam, specifically melts a certain volume of the eroded edge 3a and shapes it into an aerodynamically advantageous transition shape. This transition from the erosion contour 17 to the new contour 18 is prevented by a distribution of the rearranged material.

The length of the blade can be partially reconstructed by using a device 1 fitted with a laser unit for machining.

The improved guidance of the device 1 allows the machining unit 4 to be moved preferably without contact to the edge 3a, which was not possible according to the state of the art solution.

In the case where machining unit 4 reconfigures edge 3a by melting or welding, one of the second support 6a or 6b is attached to the unworked edge 3a, i.e. to the edge 3a which is still cold, while the other second guiding unit 6a or 6b is attached to a reconfigured section of edge 3a. The spacing of the support 6a and 6b from machining unit 4 is chosen in such a way that the support 6a and 6b are not damaged or impaired in their guiding function by the heated edge 3a in the support area.

In the case of rounding of edge 3a using a splice-off process such as grinding, milling or scraping in machining unit 4, the original erosion contour 17 can be formed into an aerodynamically advantageous splice contour 27 by reducing the length of the 21 strips, the resulting splice contour 27 being superior in aerodynamic properties to the erosion contour 17.

The machining unit 4 may also comprise a combination of the machining processes described above, arranged in a sequence along the edge 3a, so that edge 3a is machined, for example, in succession by different machining processes. For example, it is conceivable to first thicken edge 3a by welding it with additional material and then to obtain the desired shape of edge 3a by grinding or a strip-removal machining process. During this movement, the device 1 reconfigures and in particular roundes edge 3a, which has been altered in shape by erosion and other wear, into a more aerodynamically favourable shape.

A preferred direction of the device 1 can be obtained by placing the bearings 6a and 6b and the side bearings 5a and 5b at a 90° angle to each other at the axis of the blade, the bearings 6a and 6b perpendicular to the edge of the device 3a and the side bearings at a 90° angle to the edge of the device 7.

Figure 9 shows a further improvement, which is due to a problem with known re-contouring processes for removing the splice. e.g. the device described in US 6.302.625 B1 may cause the machining unit used to not be able to follow an additional deepening when the edges of the shovel are cut.

These recesses are introduced according to specifications, for example if a notch, through a stone or similar, has been inserted into the edge of the shovel. The rounding uses defined radii of total rounding and may only be introduced over a certain area of the front edge.

In addition to the unnecessary material loss when the first substrate is introduced, immersed or lowered into the depression, a reduced material loss at the lowest point of the depression results from the fact that substrate provides a linear path of the entry or exit edge.

The remedy here is to create a pressure controlled delivery of the machining unit to the edge of the machining as shown in Figure 9.

This pressure control defines the impact force of the machining unit 4. The machining unit 4 follows the edge 3a force controlled. Alternatively, the sensors can be used to realize a directional control with the same form of movement. Preferably, force controlled is worked with a pneumatic unit. It is also used to lift the machining unit 4 from the workpiece at the end of machining, so that, for example, an excessive material loss during machining, i.e. at the end of a standing device, is prevented. Furthermore, it is prevented that harmful friction at the end of a standing device causes a overheating (titanium) of the base material.

The positioning of the machine unit 4 is preferably carried out by linear guides; the resulting shift axis 9 is oriented towards the edge 3a in vertical direction 30.

List of references:

1device2blade3a edge3b suction side3c print side4working unit5a side bearing5b side bearing6a substrate6b substrate7 side direction8working direction9slide axis10adjustable power11roller12working level13contact level14contact level15axis16turning point17erosion contour18new contour19refrigerated material20base material21length of section22attachment points23replacement unit24printing and/or rolling movement26roller pair27spanning direction30

Claims (14)

1. Device (1) for recontouring a gas turbine blade (2), comprising:

   - at least one support (6a, 6b) which is configured to rest on an edge (3a) of the gas turbine blade (2) during the recontouring,

   - at least one side bearing (5a, 5b) which is configured to rest against the suction side and/or pressure side (3b, 3c) of the gas turbine blade (2) during the recontouring,

   - a machining unit (4) with which the machining of the gas turbine blade (2) is carried out, characterized in that the machining unit (4) is configured to melt at least a portion of the edge (3a) through a beam of energy in such a controlled way that the material solidifies into a new contour (18), substantially without the addition of supplementary material.
2. Device (1) according to claim 1, characterized in that the device includes at least two supports (6a, 6b) and at least two side bearings (5a, 5b).
3. Device (1) according to claim 2, characterized in that the machining unit (4) is disposed between the two supports (6a, 6b).
4. Device (1) according to any one of the preceding claims, characterized in that each of the side bearings (5a, 5b) includes at least two contacting points (22) and/or contacting surfaces.
5. Device (1) according to claim 4, characterized in that the contacting points (22) and/or contacting surfaces of at least one side bearing (5a, 5b) are disposed in a contact plane (13, 14) with the supporting point (22) or the supporting surface of a support (6a, 6b).
6. Device (1) according to claim 5, characterized in that the contacting points (22) and/or contacting surfaces of at least one further side bearing (5a, 5b) are disposed in a contact plane (13, 14) with the supporting point (22) or the supporting surface of a further support (6a, 6b).
7. Device (1) according to any one of the preceding claims, characterized in that one or more of the supports (6a, 6b) and/or side bearings (5a, 5b) are formed by pivot-mounted rollers (11).
8. Device (1) according to any one of the preceding claims, characterized in that at least one pressing assembly is provided on the suction side and/or pressure side (3b, 3c) of the gas turbine blade (2) facing the side bearings (5a, 5b).
9. Device (1) according to claim 8, characterized in that the at least one pressing assembly includes pneumatic elements, hydraulic elements and/or spring elements.
10. Device (1) according to claim 8 or 9, characterized in that the pressing assembly includes pivot-mounted rollers (11).
11. Device (1) according to one of the claims 7 to 10, characterized in that at least one roller (11) can be driven by a driving device.
12. Device (1) according to one of the claims 8 to 11, characterized in that the driving device and the machining unit (4) are controllable in a coupled manner.
13. Device (1) according to any one of the preceding claims, characterized in that the machining unit (4) includes a laser unit.
14. Device (1) according to any one of the preceding claims, characterized in that at least one of the supports (6a, 6b) includes two rollers (11) which are connected to one another by a pivot-mounted shaft (15), and wherein the machining is carried out between the two rollers (11).