Workpiece holding device

Abstract

The invention relates to a workpiece holding device (1) for a machining tool (100) designed for shortening rotor blades (3) of a turbomachine by removing material at the blade tip (2).

Description

[0001] 2024 PF00868 Foreign version

[0002] 1

[0003] Description

[0004] workpiece holding device

[0005] The invention relates to a workpiece holding device for a machining tool designed for shortening the rotor blades of a turbomachine by removing material from the blade tip. The device comprises a machining unit and a pivot axis for holding the workpiece holding device, driven by a workpiece drive unit. The machining unit and the pivot axis are spaced apart such that the blade tip of a rotor blade held in the workpiece holding device is moved in a circular arc relative to the machining unit by driving the pivot axis. The workpiece holding device has a modular design with an adapter module designed for attachment to the pivot axis, several interchangeable spacer modules of different lengths for adjusting the radius of the circular arc, and at least one angle adjustment module for setting an angle of attack of the workpiece to be machined.

[0006] The rotor blade, which it has in operation of the turbomachine, and a receiving module designed to receive a blade root of the rotor blade.

[0007] The rotor blades of a turbomachine, particularly in the form of a gas turbine or compressor, are subject to very high material stress and correspondingly high wear during operation. Therefore, they are regularly replaced with new rotor blades as part of overhaul work. The service life is advantageously chosen so that the worn rotor blades can still be repaired. Before installation on site, the new rotor blades must be machined to the correct length at the blade tip to restore the original radial gap between the blade tip and the stator of the turbomachine and thus prevent performance losses. (A delivery of 2024 PF00868 Foreign version)

[0008] 2

[0009] Producing blades of the required length from the factory is not possible due to installation and manufacturing tolerances.

[0010] Various methods are currently used to shorten the turbine blades. One possibility is to machine the turbine blades individually in a mobile machining center that can be transported to the site of the turbomachine and set up there as needed. Such a machining center, for which the workpiece holding device according to the invention is also designed, is described, for example, in DE 10 2015 205 624 A1. This machining center comprises a machining unit in the form of a belt grinding unit arranged in the lower machine area, as well as a workpiece holding unit that is attached to a pivot axis arranged in the upper machine area and driven by a workpiece drive unit.The machining unit and the swivel axis are spaced apart such that the tip of a rotor blade held in the workpiece clamping unit is moved in a circular arc relative to the machining unit by driving the swivel axis. The feed is achieved by moving the machining unit in the direction of the blade tip. The workpiece clamping unit has a modular design with an adapter module designed for attachment to the swivel axis, several interchangeable spacer modules of varying lengths for adjusting the arc radius, several angle adjustment modules, each of which allows for setting a different angle of attack of the rotor blade to be machined, as it would be during operation of the turbomachine, and a clamping module designed to hold the blade root.The receiving module comprises a cuboid made of solid material, into which a continuous groove is cut by means of wire erosion, the wall profile of which corresponds to the negative profile of a blade root of a running blade to be machined, so that the blade root can be inserted from the front of the cuboid into the groove 2024 PF00868 foreign version.

[0011] 3

[0012] The blade foot can be inserted in a form-fitting manner. For axial positioning of the blade foot within the groove, stops are attached to the front and back of the cuboid. The front stop is attached to a detachable locking element on the cuboid to allow the blade foot to be inserted into the groove. Above the free end of the blade foot, a wedge element is inserted and secured from the front of the cuboid to definitively fix the blade foot in the groove. This wedge element applies a predetermined force downwards to the blade foot, pressing it against the groove walls. The predetermined force is set by a spring-loaded bolt that presses the wedge element from the front against the rear stop. The cuboid, which is the most expensive component, must be manufactured separately for each blade foot geometry. However, due to the manufacturing process, its production is expensive and, above all, very time-consuming.In practice, the delivery time for a new cuboid can be up to 20 weeks. For this reason, the service department struggles to respond to spontaneous customer requests. Furthermore, the previously described design is ergonomically disadvantageous. It has a high weight and consists of numerous individual parts, making it difficult to handle. Additionally, the workpiece clamping repeatability is only moderate, which reduces the quality of the machining result.

[0013] Based on this prior art, it is an object of the present invention to provide an improved workpiece holding device of the type mentioned at the outset.

[0014] To solve this problem, the present invention provides a workpiece holding device for a machining machine, which is designed for shortening the rotor blades of a turbomachine by removing material at the blade tip and comprises a machining device and a pivot axis for receiving the workpiece holding device, which can be driven via a workpiece drive unit, wherein the 2024 PF00868 foreign version

[0015] 4

[0016] The machining device and the swivel axis are spaced apart from each other such that the blade tip of a rotor blade held in the workpiece holding device is moved in a circular arc relative to the machining device by driving the swivel axis, wherein the workpiece holding device has a modular design with an adapter module designed for attachment to the swivel axis, several interchangeable spacer modules of different lengths for adjusting the radius of the circular arc, at least one angle adjustment module for setting an angle of attack of the rotor blade to be machined, which it exhibits during operation of the turbomachine, and a receiving module designed for receiving a blade root of the rotor blade, characterized in that the receiving module comprises a vise with at least one pair of system jaws arranged to be movable relative to each other and a pair of clamping jaws attachable to the system jaws.which are designed for the form-fit and force-fit mounting of the blade root, wherein the workpiece holding device has several pairs of clamping jaws for different blade root geometries. A first advantage of the workpiece holding device design according to the invention is that, in principle, only the clamping jaws need to be exchanged to accommodate differently designed blade root geometries, while the vise, designed in particular as a centering clamp, and the system jaws can continue to be used. The production of the respective clamping jaw pairs is significantly less expensive than that of the previously described cuboids. Furthermore, the weight and size are considerably smaller, which improves ergonomics.This greatly facilitates the transport and thus the handling of the workpiece holding device. Furthermore, the vise and the clamping surfaces of the jaws, which correspond to or are modeled on the negative profile of the blade base being held, achieve a positive and non-positive clamping of the workpiece with very high clamping repeatability, leading to excellent machining results in the machine tool. 2024 PF00868 Foreign version

[0017] 5

[0018] Preferably, the workpiece holding device has a single angle adjustment module designed to be attached in various predetermined angular positions to the module located immediately adjacent to the angle adjustment module in the direction of the adapter module, preferably to an adjacent spacer module. Accordingly, a separate angle adjustment module is not required for each predetermined angular position, which reduces the number of components and thus costs. Fewer components also need to be transported, which improves ergonomics.

[0019] Advantageously, several different pairs of system jaws are provided. While the coarse adjustment of the circular arc radius, which simulates the wheel diameter of the turbomachine on which the impeller to be machined is held, is achieved by selecting the appropriate spacing module(s), fine adjustment can be made by appropriately designing and selecting the system jaw pairs.

[0020] Preferably, at least one fixed stop is provided, designed to define an axial position of a blade root held between the clamping jaws. Such a stop improves clamping repeatability or significantly facilitates achieving it.

[0021] The axial position of at least one fixed stop is advantageously adjustable, for example via a spindle, so that it can be adapted to different blade root lengths, thereby further reducing the number of components.

[0022] According to one embodiment of the present invention, fixed stops of different sizes are provided, wherein 2024 PF00868 Foreign version

[0023] 6

[0024] Each size can be suitable for a single or for several different shovel foot geometries.

[0025] Preferably, at least one axially spring-loaded stop is provided, which is arranged axially opposite the at least one fixed stop and presses a blade base held between the clamping jaws against the at least one fixed stop with a predetermined spring force. Thanks to such spring-loaded stops, the clamping repeatability is further improved. The at least one spring-loaded stop is advantageously positioned on one of the clamping jaws of a clamping jaw pair.

[0026] The axial position of at least one spring-loaded stop is advantageous for adjusting the spring force, for example via a threaded spindle or a thread.

[0027] According to one embodiment of the present invention, at least one stop is held on a locking part which can be detachably fastened to both clamping jaws, wherein the locking part and the clamping jaws are in particular designed to be detachably fastened to one another using locking bolts, preferably ball locking bolts.

[0028] It is advantageous to have at least one stop held against one of the two clamping jaws.

[0029] The clamping jaws are preferably made of plastic, which allows for very inexpensive production. However, the clamping jaws can also be made of aluminum or stainless steel.

[0030] The clamping jaws are advantageously additively manufactured, which reduces the production time and thus the delivery time to 1 to 2 weeks. This also allows for a very quick response to spontaneous orders. 2024 PF00868 Foreign version

[0031] 7

[0032] Advantageously, the clamping jaws are marked with a label indicating, in particular, the turbine type and / or turbine stage, the installation position of the clamping jaw, the angular position to be set for the angle adjustment module, the torque on the vise, the total length of the spacer modules, and / or a pair of system jaws to be used. Such a label significantly facilitates handling.

[0033] Further features and advantages of the present invention will become clear from the following description with reference to the accompanying drawing. Therein is

[0034] Figure 1 shows a perspective front view of a workpiece holding device according to an embodiment of the present invention, in which a guide vane is held;

[0035] Figure 2 is an enlarged perspective front view from a low angle, showing a lower area of ​​the arrangement shown in Figure 1;

[0036] Figure 3 shows an enlarged perspective front view from a low angle, showing a lower area of ​​the workpiece holding device shown in Figure 1;

[0037] Figure 4 is a perspective side view of the area shown in Figure 3;

[0038] Figure 5 is a perspective view showing the area shown in Figure 3 from a low angle;

[0039] Figure 6 shows a perspective rear view of the area shown in Figure 3;

[0040] Figure 7 is a perspective view showing the outside of a clamping jaw located on the right in Figure 1; 2024 PF00868 Foreign version

[0041] 8

[0042] Figure 8 is a perspective view showing an inside view of the clamping jaw shown in Figure 7;

[0043] Figure 9 is a perspective view analogous to Figure 7, which shows the clamping jaw with inserted spring stops and locking bolts;

[0044] Figure 10 is a perspective view analogous to Figure 8, which shows the clamping jaw with inserted spring stops and locking bolts;

[0045] Figure 11 shows a perspective view of a locking element with an inserted fixed stop; and

[0046] Figure 12 shows a front view of a well-known machining machine for shortening barrel blades.

[0047] Figures 1 to 11 show a workpiece holding device 1 according to an embodiment of the present invention. The workpiece holding device 1 is designed for a known machining machine 100 of the type described in DE 10 2015 205 624 A1 and shown in Figure 12. This machining machine 100 is used for shortening the rotor blades of a turbomachine by removing material from the blade tip. It comprises a frame 101, a machining device 102, preferably in the form of a belt sander, which is movable up and down, and a pivot axis 104, driven by a workpiece drive unit 103, which accommodates a second workpiece holding device 105, which, according to the invention, is to be replaced by the workpiece holding device 1.The machining device 102 and the swivel axis 104 are spaced apart such that the blade tip 2 of a guide blade 3 held in the workpiece holding device 103 is moved in a circular arc relative to the machining device 102 by driving the swivel axis 104. 2024 PF00868 Foreign version.

[0048] 9

[0049] The workpiece holding device 1 shown in Figures 1 to 11 has a modular design. It comprises an adapter module 4 at the upper free end, several interchangeable spacer modules 5 of different lengths 1, a single angle adjustment module 6, and a holding module 7 at the lower end.

[0050] The adapter module 4 has a connecting section 9 in its upper area, which is designed to detachably mount the adapter module 4 to the pivot axis 104, whereby the cover that encompasses the pivot axis 104 from above is not shown in Figure 1. A flange section 10 is formed in the lower area of ​​the adapter module 4 to connect the adapter module 4 to one of the spacer modules 5 using fastening screws.

[0051] The spacer modules 5 each have a flange section 11 at their upper and lower ends, each designed according to the flange section 10 of the adapter module 4, so that they can be connected to the adapter module 5 and to each other using fastening screws. The spacer modules 5 are available in various lengths 1 and can be combined in different ways to set a desired swivel radius with which the blade tip 2 of a turbine blade 3 to be machined is swiveled about the swivel axis 104 of the machining machine 100. Accordingly, turbine blades 3 of different lengths, mounted on impeller discs of different diameters in the turbomachine, can be machined. The number and respective lengths 1 of the spacer modules 5 are therefore determined by the design of the turbomachine whose turbine blades 3 are to be machined.In the embodiment shown in Figure 1, three spacer modules 5 are combined, wherein the workpiece holding device 1 has more than three adapter modules 5. 2024 PF00868 Foreign version.

[0052] 10

[0053] The angle adjustment module 6 serves to set the angle of attack of the impeller 3 to be machined, as it exhibits during operation of the turbomachine, in order to simulate the installation position of the impeller 3 in the turbomachine in the machining machine 100. The angle adjustment module 6 is designed in the form of a plate and has two handles 12 on the side for ease of handling. Drilled patterns are incorporated into the plate, allowing the angle adjustment module 6 to be attached to the adjacent spacer module 5 in various rotational positions, specifically 0°, 15°, and 30°. These rotational positions depend on the different angles of attack exhibited by the impeller 3 to be machined within the turbomachine.

[0054] The receiving module 7, designed to receive a blade root 8 of the turbine blade 3, which in this case is a turbine blade, is arranged on the underside of the angle adjustment module 6 and connected to it by means of fastening screws. It comprises a vise 13, in this case several pairs of system jaws 14 arranged to be movable relative to each other, and several pairs of clamping jaws 15 that can be attached to the system jaws 14. In the illustrated embodiment, the vise 13 is designed as a centering clamp. The system jaws 14 are designed such that fine adjustment of the swivel radius is possible by selecting a suitable pair of system jaws. The clamping jaw pairs are designed for the positive and force-fit reception of the respective blade roots 8 of the turbine blades 3 to be machined.The opposing inner surfaces 16 of the clamping jaws 15 form at least a partial negative mold of the blade root geometry, allowing them to fit snugly against the corresponding blade root 8. The clamping jaws 15 are preferably made of plastic, which enables very cost-effective manufacturing. One of the 2024 PF00868 foreign version.

[0055] 11

[0056] The clamping jaws 15 of each pair of clamping jaws are L-shaped, as shown in Figures 7 to 10. Three spring-loaded stops 17, arranged one above the other and projecting inwards towards the front, are screwed into corresponding threaded through-holes in the angled rear side, extending axially from the rear. On the front side, the clamping jaws 15 of each pair of clamping jaws form mounting sections 18 of a common holder for a locking element 19, which can be inserted into the mounting sections 18 and, in this case, fastened to the clamping jaws 15 using two locking bolts 20, in this case ball locking bolts. For this purpose, the mounting sections 18 and the locking element 19 are provided with corresponding through-holes 21 for the insertion of the locking bolts 20, one of which is designed as an elongated hole extending in the direction of movement of the clamping jaws 15.A fixed stop 22 is screwed into an axially extending threaded through-hole in the center of the locking element 19, projecting rearward as shown in Figure 11. Preferably, the workpiece holding device 1 has several of the locking elements 19 shown in Figure 11 with stops 22 of varying lengths, so that a suitable locking element 19 can be selected depending on the blade 3 being machined. The clamping jaws 15 are made of plastic and additively manufactured, resulting in a short production time and thus a short delivery time.In the illustrated embodiment, the clamping jaws 15 are provided with an inscription 23, from which the turbine type, the turbine stage, the installation position of the clamping jaw 15, the angular position to be set of the angle adjustment module 6, the total length of the spacer modules 5 to be used, the pair of system jaws 14 to be used and the torque on the vise 13 can be derived in succession.

[0057] For machining a guide vane 3, depending on its geometry and installation situation, the following are specified in the 2024 PF00868 foreign version.

[0058] 12

[0059] In a first step, the appropriate spacer modules 5, system jaws 14, and clamping jaws 15, as well as the suitable closure part 19 with the fixed stop 22 attached to it, are assembled on the turbomachine. The settings of the stops 17 and 22 are then checked. In a further step, the modules are assembled and attached to the swivel axis 104 of the machining machine 100, taking care during assembly to ensure that the angle adjustment module 6 is mounted at the correct angle.

[0060] The blade root 8 of the blade 3 to be machined is now inserted from the front between the clamping jaws 15, with the jaws 15 slightly spread apart relative to their clamping position, until it abuts the spring stops 17 at the rear. The locking element 19, with a suitably long stop 22, is then inserted into the retaining sections 18 formed by the clamping jaws 15 such that the stop 22 rests against the blade root 8. The locking element 19 is then fastened to the clamping jaws 15 using the locking pins 20. In a further step, the clamping jaws 15 are moved into their clamping position until a predetermined torque is reached. The through-hole 21, formed as an elongated slot in the locking element 19, allows the clamping jaws 15 to move despite the locking element 19 already being installed.The shovel tip 2 can now be machined in the usual way in the machining machine 100 and shortened to achieve the desired gap dimension.

[0061] The workpiece clamping device 1 described above is advantageous in that it comprises only a few modules, each with a comparatively low weight and ease of handling. The production of the individual clamping jaw pairs can be carried out quickly and cost-effectively, allowing for rapid response to short-notice orders. Furthermore, a very high clamping repeatability can be achieved, resulting in good manufacturing quality. 2024 PF00868 Foreign version

[0062] 13

[0063] It should be noted that the receiving module 7 for machining compression blades differs preferably from the previously described receiving module 7 for machining turbine rotor blades in that at least one spring-loaded stop 17 is positioned in the front area and at least one fixed stop 22 is positioned in the rear area of ​​the receiving module 7.

[0064] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without leaving the scope of protection of the invention.

[0065] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

2024 PF008 68 Foreign version 14 Patent claims 1. Workpiece holding device ( 1 ) for a machining machine ( 100 ), which is designed for shortening the running blades (3) of a flow machine by removing material from the blade tip (2) and includes a machining device (102) as well as a swivel axis (104) that can be driven via a workpiece drive unit (103) for receiving the workpiece holding device (1), wherein the cutting device ( 102 ) and the pivot axis ( 104 ) are spaced apart from each other such that the blade tip ( 2 ) of a running blade ( 3 ) held in the workpiece holding device ( 1 ) is moved in a circular arc relative to the cutting device ( 102 ) by driving the pivot axis ( 104 ), wherein the workpiece holding device ( 1 ) has a modular design with an adapter module ( 4 ), which is designed for attachment to the pivot axis ( 104 ), several interchangeable spacer modules ( 5 ) of different lengths ( 1 ) for adjusting the circular arc radius, at least one angle adjustment module ( 6 ) for adjusting an angle of attack s of the running blade ( 3 ) to be machined, which it has during operation of the flow machine, and a receiving module ( 7 ), that the barrel blade (3) is designed to receive a blade foot ( 8 ). characterized by the fact that ss there s The receiving module (7) comprises a vise (13) with at least one pair of system jaws (14) arranged to be movable relative to each other and a pair of clamping jaws (15) that can be attached to the system jaws (14) and are designed to provide a positive and force-fit connection for the shovel foot (8). wherein the workpiece holding device ( 1 ) has several pairs of clamping jaws ( 15 ) for different blade root geometries. 2024 PF008 68 Foreign version 15 2. Workpiece holding device ( 1 ) according to claim 1, characterized in that it has a single angle adjustment module ( 6 ) which is designed to be attached to the module in different predetermined angular positions, since it is arranged in the direction of the adapter module ( 4 ) immediately adjacent to the angle adjustment module ( 6 ), preferably on an adjacently arranged spacer module ( 5 ).

3. Workpiece holding device ( 1 ) according to claim 1 or 2, characterized in that it has several different pairs of system jaws ( 14 ).

4. Workpiece holding device ( 1 ) according to one of the preceding claims, characterized in that at least one fixed stop ( 22 ) is provided which is designed to define an axial position of a blade foot ( 8 ) held between the clamping jaws ( 15 ).

5. Workpiece holding device ( 1 ) according to claim 4, characterized in that the axial position of the at least one fixed stop ( 22 ) is adjustable.

6. Workpiece holding device ( 1 ) according to claim 4 or 5, characterized in that fixed stops ( 22 ) of different sizes are provided.

7. Workpiece holding device ( 1 ) according to one of claims 4 to 6, characterized in that at least one axially spring-loaded stop ( 17 ) is provided, which is arranged axially opposite the at least one fixed stop ( 22 ) and presses a paddle foot ( 8 ) held between the clamping jaws ( 15 ) against the at least one fixed stop ( 22 ) with a predetermined spring force.

8. Workpiece holding device ( 1 ) according to claim 7, characterized in that the axial position of the at least one spring stop ( 17 ) is adjustable for setting the predetermined spring force. 2024 PF008 68 Foreign version 16 9. Workpiece holding device ( 1 ) according to one of claims 4 to 8, characterized in that at least a stop ( 17, 22 ) is held at a steep angle ( 19 ) on a closure which can be detachably fastened to both clamping jaws ( 15 ), wherein the closure is steep ( 19 ) and the clamping jaws ( 15 ) are in particular designed to be detachably fastened to one another using locking bolts ( 20 ), preferably ball locking bolts.

10. Workpiece holding device ( 1 ) according to one of claims 4 to 9, characterized in that at least a stop ( 17, 22 ) is held on one of the two clamping jaws ( 15 ).

11. Workpiece holding device ( 1 ) according to one of the preceding claims, characterized in that the clamping jaws ( 15 ) are made of plastic, aluminum or stainless steel.

12. Workpiece holding device ( 1 ) according to one of the preceding claims, characterized in that the clamping jaws ( 15 ) are additively manufactured.

13. Workpiece holding device ( 1 ) according to one of the preceding claims, characterized in that the clamping jaws ( 15 ) are provided with an inscription ( 23 ) from which, in particular, the turbine type and / or the turbine stage or the installation position of the clamping jaw ( 15 ) and / or the angular position to be set of the angle adjustment module ( 6 ) and / or the torque on the vise ( 13 ) and / or the total length of the spacer modules ( 5 ) and / or a pair of system jaws ( 14 ) to be used can be seen.

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