GB2303188A

GB2303188A - An arrangement for connecting two turbine rotor discs

Info

Publication number: GB2303188A
Application number: GB9514310A
Authority: GB
Inventors: Michael Charles Taylor
Original assignee: BMW Rolls Royce GmbH
Current assignee: Rolls Royce Deutschland Ltd and Co KG
Priority date: 1995-07-13
Filing date: 1995-07-13
Publication date: 1997-02-12
Anticipated expiration: 2015-07-13
Also published as: GB9514310D0; GB2303188B; DE19627386A1

Description

2303188 An arrangement for connecting two turbine rotor discs

The invention relates to an arrangement for connecting two turbine rotor discs, the arrangement comprising a number of studs, which carry nuts at both ends, for insertion in bores formed in arms connecting the discs, so as to clamp the discs together with an accurate fit. The prior art can be found, for example, in EP 0 556 514 A2.

As a rule, there is very little space for a bolted connection between two turbine rotor discs whose facing connecting arms are clamped together by a number of expansion bolts disposed substantially in a circle. As a result of this narrow space, it is not possible to use bolts having boltheads; instead, studs having nuts at both ends have to be used. In such cases the studs, especially expansion studs have to be exactly positioned and the two nuts have to be tightened practically simultaneously with a defined torque to obtain the desired tension. Owing to the narrow space, however, it is impossible to use two tools simultaneously for tightening the first bolted joint and simultaneously locking the second nut. The aim of the present invention is to remedy this situation.

To this end, according to the invention, the stud has a flank by means of which, after the first nut abutting the connecting arm of the first rotor disc has been tightened, the stud abuts in the exact position against that side of the connecting arm of the first disc which faces the second rotor disc. Advantageous other features are - 2 disclosed in the sub-claims.

The invention will be explained in detail with reference to a preferred embodiment shown in the accompanying drawings, in which:

Figure 1 is a partial section through an arrangement according to the invention for connecting two turbine rotor discs; Figure 2 is a larger-scale view of the bolted connection between the two discs; and Figure 3 shows view "All of Figure 2.

Reference 1 denotes a first rotor disc, for example of an aircraft gas turbine, which is connected to a second rotor disc 2 by a bolted joint. To this end, the two arms la, 2a connecting the discs are clamped to one another via a number of expansion studs 4 carrying nuts 5a, 5b at both ends and disposed substantially in a circle around the longitudinal axis 3 of the turbine.

Figure 1 illustrates the restricted space for installation. The bolted joint has to be fitted "blind', from the interior, i.e. from the longitudinal axis 3 of the turbine. To simplify the process and obtain an accuratelyfitting and accurately-positioned bolted joint, the connecting arrangement shown on a larger scale in Figure 2 is proposed.

First, it will be assumed that only the left rotor disc 1 is present. The first nuts 5a held via ring segment plates 6 are, firstly, attached to the disc-connecting arm la, corresponding to the respective bores 7 for inserting - 3 the expansion stud 4 into the arm la. To this end, the first nuts Sa are constructed in a known manner as rivet nuts which rest in a known manner on the annular segment plates. Next, a sleeve 8 is inserted from the right into each bore 7 and abuts the arm la whereby the sleeve serves in turn as an abutment surface for the stud 4 which is then inserted into the bore 7. This stud 4 has a flank 9 formed by a spring ring 11 inserted into a groove 10 in the stud 4.

Finally, the stud 4 is screwed into the first nut Sa. To this end, the stud 4 is rotated, using a suitable tool, until the spring ring 11 abuts the sleeve 8, so that finally the segment plate 6 presses against the connecting arm la. The stud is torque tightened to a perdetermined figure which is suitably in excess of the maximum self locking feature torque of the anchor nut 5b, which is screwed on the stud 4 later. Thereby the stud 4 is exactly positioned with the help of flank 9, spring ring 11 and sleeve 8.

The resulting through-bolt joint, after being pref itted on the f irst turbine rotor disc 1, now enables the second rotor disc 2 to be slipped on and fitted. Accordingly, the bores 7 through the disc 2 are slid over the individual expansion stud 4 until the two disc-connecting arms la, 2b abut one another. The second nut 5b is then screwed on to the right-hand free end of the stud 4, using a special spanner. The second nut 5b is tightened at a certain torque, without altering the position of the stud 4.

- 4 The above-described arrangement for connecting the two turbine rotor discs 1, 2 is highly efficient and reliable, in spite of the restricted space. If the throughbores 7 are suitable designed, the stud 4 can of course abut directly against the disc-connecting arm la without the need of the sleeve 8. Also, the flank 9 can be machined on the stud 4, and the spring ring 11 can be replaced by a snap ring. of course, a number of other modifications can be made to the embodiment shown without departing from the claims.

Claims

C L A I M S

1. An arrangement for connecting two turbine rotor discs (1, 2), the arrangement comprising a number of studs (4), carrying nuts (5a, 5b) at both ends, for insertion in bores (7) in the arms (1a, 2a) connecting the discs so as to clamp the discs (1, 2) together with an accurate fit, wherein the stud (4) has a f lank (9) by means of which, after the first nut (5a) abutting the connecting arm (1a) of the f irst rotor disc (1) has been tightened, the stud (4) abuts in the exact position against that side of the connecting arm (1a) of the first disc which faces the second rotor disc (2).

2. An arrangement according to claim 1, characterised in that the flank (9) of the stud (4) is formed by a spring ring (11) inserted into a groove (10) in the stud (4).

3. An arrangement according to claim 1 or claim 2, characterised in that the flank (9) of the stud (4) abuts a sleeve (8) inserted into the bore (7) in the connecting arm (1a) of the first disc (1).

4. An arrangement according to any of the preceding claims, characterised in that the first nuts (5a) abutting the first disc (1) are in the form of rivet nuts resting on annular segments (6).