METHOD AND DEVICE FOR SECURING A THREADED ELEMENT SCREWED INTO A THREADED SEAT, METHOD FOR MOUNTING AT LEAST ONE BALANCING WEIGHT OF A TURBINE, AND A TURBINE

Abstract

A method for securing a threaded element screwed into a threaded seat wherein the threaded element is at least partially plastically deformed by a deformation element of a tool such that the threaded element is subsequently arranged secured against rotation in the threaded seat. The tool is thereby placed axially in front of the threaded element in that a guide element of the tool is inserted axially in a drive mount of the threaded element, wherein the deformation element thus placed axially in front of the threaded element is accelerated in the direction of the threaded element, and wherein the deformation element shifts relatively with respect to the guide element inserted in the drive mount such that at least the first thread of the threaded element and/or the threaded seat facing the tool is deformed by the deformation element in order to secure the threaded element in the threaded seat.

Claims

1. A method for securing a threaded element that is screwed into a threaded balancing weight seat of a turbine arrangement and that is configured as a mounting screw, the method comprising: at least partially plastically deforming at least the threaded element screwed into the threaded balancing weight seat by means of deforming means of a tool such that it is then arranged in a rotationally secure manner in the threaded balancing weight seat, placing the tool axially in front of the threaded element, in that a guide element of the tool is plugged axially into a drive recess of the threaded element, accelerating the deforming means placed axially in front of the threaded element in the direction of the threaded element, and moving the deforming means move relative to the guide element plugged into the drive recess such that at least the first thread turn, oriented toward the tool, of the threaded element and/or of the threaded balancing weight seat is deformed by the deforming means in order to secure the threaded element in the threaded balancing weight seat.

2. A method for installing at least one balancing weight of a turbine or a steam turbine, the method comprising: immobilizing the at least one balancing weight by means of a threaded element configured as a mounting screw, during a final balancing process carried out under operational conditions, tightening the threaded element with a defined torque in a threaded balancing weight seat, at least partially plastically deforming at least the threaded element screwed into the threaded balancing weight seat by deforming means of a tool such that it is then arranged in a rotationally secure manner in the threaded balancing weight seat, placing the tool axially in front of the threaded element, in that a guide element of the tool is plugged axially into a drive recess of the threaded element, and accelerating the deforming means placed thus axially in front of the threaded element in the direction of the threaded element, moving the deforming means relative to the guide element plugged into the drive recess such that at least the first thread turn, oriented toward the tool, of the threaded element and/or of the threaded balancing weight seat is deformed by the deforming means in order to secure the threaded element in the threaded balancing weight seat.

3. The method as claimed in claim 1, wherein the guide element is plugged into a drive recess of the threaded element such that the deforming means is oriented centrally with respect to the threaded element.

4. The method as claimed in claim 1, wherein the tool is guided through an access bore of a turbine arrangement as far as the threaded element, in order to plastically deform the threaded element and/or the threaded seat.

5. The method as claimed in claim 1, wherein less than 25%, of the thread of the threaded element and/or of the threaded balancing weight seat is deformed plastically.

6. A turbine balancing weight securing device for securing a threaded element that is screwed into a threaded balancing weight seat and that is configured as a mounting screw, using a tool for plastically deforming at least the threaded element and for carrying out a method as claimed in claim 1, wherein the tool comprises: a supporting body on which there are arranged on one hand a guide element that can be plugged into the threaded element configured as a mounting screw, and on the other hand deforming means for plastically deforming the threaded element and/or the threaded balancing weight seat, and wherein the guide element is mounted on the supporting body such that it can be displaced relative to the deforming means.

7. The turbine balancing weight securing device as claimed in claim 6, wherein the guide element is mounted such that it can move linearly within the supporting body along the central longitudinal axis of the tool.

8. The device as claimed in claim 6, wherein the guide element is arranged, on the head side of the tool, such that it projects at least temporarily beyond the deforming means.

9. The device as claimed in claim 6, wherein the guide element is mounted spring-preloaded within the supporting body.

10. The device as claimed in claim 6, wherein the guide element is arranged such that it cannot rotate about the central longitudinal axis of the tool.

11. The device as claimed in claim 6, wherein an anti-rotation bolt is arranged on the guide element, which bolt is guided radially so as to project into a guide slot, of the supporting body, that extends in the direction of the central longitudinal axis of the tool.

12. The device as claimed in claim 6, wherein the guide element has a male hexagon driver bit.

13. The device as claimed in claim 6, wherein the deforming means comprise a multiplicity of conical deforming tips which are arranged concentrically around the guide element.

14. The device as claimed in claim 6, wherein the tool has a recess for an impact arm, which recess is arranged at one end of the supporting body, oriented away from the guide element.

15. The device as claimed in claim 6, wherein the device is adjustable in length in order to be adapted to access bores of different lengths.

16. A turbine or a steam turbine, having at least one rotor that rotates and holds turbine blades, and having balancing weights for balancing the rotating rotor, wherein the balancing weights are immobilized by means of a mounting screw configured as a threaded element, and wherein the threaded element is secured in its threaded balancing weight seat using a captive retainer, wherein the captive retainer is created by a plastic deformation of the threaded element and/or of the threaded balancing weight seat, wherein only a first turn of the thread of the threaded element and/or of the threaded balancing weight seat is plastically deformed, such that the threaded element can once again be unscrewed from its threaded balancing weight seat in order to be able to move or remove the balancing weight.

17. The turbine as claimed in claim 16, wherein less than 25%, of the thread of the threaded element and/or of the threaded balancing weight seat is destroyed by the plastic deformation.

18. The turbine as claimed in claim 16, wherein less than 20% of the thread of the threaded element and/or of the threaded balancing weight seat is destroyed by the plastic deformation.

19. The method as claimed in claim 1, wherein less than 20% of the thread of the threaded element and/or of the threaded balancing weight seat is destroyed by the plastic deformation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In the drawings:

[0051] FIG. 1 shows, schematically, a view of a device, in particular for the final installation of a balancing weight on a steam turbine, having a tool for plastically deforming a thread of a threaded seat of a mounting screw of the balancing weight,

[0052] FIG. 2 shows, schematically, a positional view of the balancing weight in its final position in an annular slot of a steam turbine rotor, and

[0053] FIG. 3 shows, schematically, a plan view of the balancing weight of FIG. 2 in its final position in the annular slot of the steam turbine rotor.

DETAILED DESCRIPTION OF INVENTION

[0054] The device 1 shown in FIG. 1 is configured in this exemplary embodiment such that it is provided for securing a threaded element 3, here in the form of a mounting screw 4 of a balancing weight 5, which is screwed into a threaded seat 2 (see FIGS. 2 and 3).

[0055] To that end, the device 1 is equipped with a tool 10 by means of which at least the threaded seat 2 introduced into the balancing weight 5 and expediently also the mounting screw 4 can be plastically deformed. Thus, not only advantageously the balancing weight 5 but also the mounting screw 4 is plastically deformed with the device 1 for the purpose of creating captive retention for the mounting screw 4.

[0056] The tool 10 comprises on one hand a guide element 12 that can be plugged into the threaded element 3, more specifically into a drive recess 11 (see FIG. 2) of the threaded element 3, such that the tool 10 can be placed centrally in front of the threaded element 3 in an operationally secure manner, before especially the threaded seat 2 is plastically deformed by the tool 10. Since the threaded element 3 shown is a mounting screw 4 in the form of a hexagon-socket grub screw, the guide element 12 is equipped, at its end, with a corresponding male hexagon driver bit 13.

[0057] On the other hand, the tool 10 comprises deforming means 14 for plastically deforming at least the threaded seat 2. In this exemplary embodiment, the deforming means 14 are embodied as a hardened crown ring 15 that provides a multiplicity of hardened deforming tips 16 (numbered only by way of example) that are arranged concentrically around the male hexagon driver bit 13.

[0058] The tool 10 has an elongate metallic supporting body 17 that supports both the guide element 12 and the deforming means 14 such that the guide element 12 is mounted on the tool 10 such that it can be displaced relative to the deforming means 14.

[0059] In this context, the supporting body 17 forms a cavity 18 in which the guide element 12 is mounted, by means of a spring element 19, such that it can slide linearly within the supporting body 17 along the central longitudinal axis 20 of the tool 10.

[0060] In that respect, the guide element 12 is permanently pressed, with a certain preload, outward and in the direction 21 of the deforming means 14, such that, in the resting state, the guide element 12 is arranged, on the head side 22 of the tool 10, such that it projects beyond the deforming means 14. Thus, the tool 10 with its male hexagon driver bit 13 can be relatively easily threaded even through a relatively long access bore 23 of approximately 600 mm (see FIG. 2) into the drive recess 11 of the threaded element 3, deep in the access bore 23, and thus plugged in, whereby the deforming means 14 of the tool 10 can be placed with great precision in front of the threaded seat 2 and the threaded element 3 and in particular concentrically around the drive recess 11 of the threaded element 3. This makes it possible to plastically deform the threaded seat 2 in the transition region to the threaded element 3 and possibly also the edge region of the threaded element 3 such that the threaded element 3 is secured in the threaded seat 2 such that it cannot rotate but can be released using a rotary tool (not shown). In this context, only the first turn of the thread of the threaded seat 2 and, depending on the configuration of the threaded element 3, also only one thread turn of the threaded element 3, is/are plastically deformed such that the threaded element 3 can be removed from its threaded seat 2.

[0061] To make it simple to thread or plug the guide element 12 into the drive recess 11 of the threaded element 3, the guide element 12 is arranged such that it cannot rotate about the central longitudinal axis 20 of the tool 10. To that end, the guide element 12 has a rotation-preventing bolt 24 which projects radially from the central longitudinal axis 20 and projects into a guide slot 25, of the supporting body 17, that extends in the direction of the central longitudinal axis 20 of the tool 10, and is thus guided axially along the central longitudinal axis 20.

[0062] The length of the device 1 can be set simply, in terms of construction, using an exchangeable impact arm 26 which can be pushed on, at the back of the tool 10, at a corresponding recess 27 formed on the supporting body 17. The recess 27 is thus arranged at an end 28 of the supporting body 17 oriented away from the guide element 12, that is to say at the back.

[0063] The approximately 600 mm-long access bore 23 on a steam turbine arrangement 29 of a steam turbine 30 is clearly visible in the illustration in FIG. 2. The access bore 23 leads to the position P where the balancing element 5, shown by way of example, is placed within the steam turbine arrangement 29. The entrance to the access bore 23 can be closed with a closure element 31 after completion of final installation of the balancing weight 5.

[0064] As shown in the illustration of the steam turbine arrangement 29 in FIG. 3, the balancing weight 5 is already secured, by the mounting screw 4, in an annular slot 32 of a steam turbine rotor 33 of the steam turbine 30. In this context, the mounting screw 4 is peened in the threaded seat 2 of the balancing weight 5 by the device 1 described in FIG. 1. Corresponding plastic deformation of the threaded seat 2 of the balancing weight 5 on one hand, and possibly of the mounting screw 4 on the other hand, creates captive retention such that the mounting screw 4 cannot unintentionally come loose in the threaded seat 2. Clearly visible are the peening indentations 34, caused by the plastic deformation, on the outer rim 35 of the mounting screw 4 and of the balancing weight 5.

[0065] Although the invention has been described and illustrated in more detail by way of the preferred exemplary embodiment, the invention is not restricted by this disclosed exemplary embodiment and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.