GB2610628A

GB2610628A - Castellated nut

Info

Publication number: GB2610628A
Application number: GB2113021.6A
Authority: GB
Inventors: Wetzorke Ines; Mosley John; Mc Lachlan Grant; Williams David
Original assignee: Rolls Royce Deutschland Ltd and Co KG; Rolls Royce PLC
Current assignee: Rolls Royce Deutschland Ltd and Co KG; Rolls Royce PLC
Priority date: 2021-09-13
Filing date: 2021-09-13
Publication date: 2023-03-15
Also published as: GB202113021D0

Abstract

A nut for fixing parts to one another comprises an inner thread (101) that defines an axis, a tool interface (109) having a tool interface diameter (see figure 1B), and a slotted part (102) that has a plurality of elongate slots (103) and extends from an axial end (107) of at least one of the slots (103) to an axial end (106) of the nut (100A-100E) with an axial length (Y). Each of the slots (103) is adapted for receiving a pin (200, see figure 2A) and has a slot length (S). The axial length (Y) of the slotted part (102) is equal to or larger than the tool interface diameter (W) and/or the slot length (S) is larger than 50% of the tool interface diameter (W).

Description

CASTELLATED NUT

Description

The present disclosure relates to a nut and to a gas turbine comprising such a nut.

Castellated or slotted nuts are nuts having a part including slots which are used to receive a pin that fits through two slots and a hole in the screw onto which the nut is 10 screwed. The pin then prevents the nut from being unscrewed.

In various applications, e.g., in gas turbines, castellated nuts are needed for different bolt lengths, e.g. for fixing several pairs of components with varying thicknesses to one another. There are several types of castellated nuts on the market; however, each available nut only fits for one specific bolt length. Therefore, a number of different bolt lengths needs to be provided and kept in storage.

It is an object to provide an improved nut.

According to an aspect there is provided a nut for fixing one part to another. The nut comprises an inner thread that defines a thread axis, a tool interface having a tool interface diameter (in particular outer diameter), and a slotted part that has a plurality of elongate slots and extends from an axial end of at least one of the slots to an axial end of the nut. The slotted part has an axial length. Each of the slots is adapted for receiving a pin and has a slot length, wherein the axial length of the slotted part is equal to or larger than the tool interface diameter and/or the slot length is larger than 50% of the tool interface diameter.

By this, the slot length is designed such as to securely accommodate a pin at different axial positions of the slots. It is possible to provide one size of castellated nut that can be used to service several different engine locations that require differing lengths of bolts. In other words, the nut may easily accommodate a variation in position of pin holes in a bolt at several different joints. -2 -

The tool interface may, e.g., be hexagonal, in particular may have a hexagonal outer shape. The nut may be a hex nut.

According to an embodiment the slot length is about 90% of the tool interface diameter, e.g., 90% +1-5% or +/-2%.

The nut may further comprise an unslotted part extending from another end of the nut to the slotted part. This end may be referred to as first end of the nut, while the axial end of the nut, to which the slotted part extends to, may be referred to as second end of the nut. The nut extends in axial direction between the first end and the second end. The unslotted part may comprise the tool interface. Alternatively, the tool interface is provided at the slotted part. The unslotted part comprises no slots.

According to an aspect there is provided a nut for fixing one part to another, which is optionally designed in accordance with the nut of the aspect described above. The nut comprises an inner thread with a thread size and an axial thread length. The nut further comprises a slotted part with a plurality of elongate slots adapted for receiving a pin and having a slot width and a slot length, wherein the slot length is greater than or equal to the thread size and/or measures at least 2 times the slot width and/or is greater than or equal to 80%, in particular 90% of the inner diameter and/or the outer diameter of the slotted part. Optionally, the slot length measures at least 2 times the slot width and is greater than or equal to the thread size and is greater than or equal to 80%, in particular 90% of the inner diameter and/or the outer diameter of the slotted part.

Again, the slot length is designed such as to securely accommodate a pin at different axial positions of the slots in this way.

In an embodiment, the slot length measures at least 3 times the slot width or more.

Alternatively or additionally, the slot length may measure 1.0 to 2.0 times the thread size, in particular 1.1 to 1.5 times the thread size, more particularly 1.2 to 1.4 times the thread size. -3 -

The nut has a total axial length (from the first end to the second end). Each of the slots may have a slot length measuring 0.4 to 0.7, in particular 0.45 to 0.65, of the total axial length.

All of the slots may have the same slot length.

Pairs of slots are arranged opposite to one another so that a pin may be pushed through both slots of the pair, in particular such that the pin also goes through the thread axis of the nut. When the nut is screwed onto a bolt with a hole, the pin may be pushed through the pair of slots and the hole in the bolt so as to lock the nut against a rotation with respect to the bolt and thus from loosening.

The slots may be aligned in parallel to the thread axis of the inner thread.

In an alternative the slots are closed at both axial ends. In particular at the end of the slots facing away from the unslotted part, a bridging section may be provided that connects adjacent strips of material between each two slots. By this, a vibration of the strips of material may be prevented, in particular when the nut is used in a potentially vibrating environment such as a gas turbine.

According to another alternative, the slots may be open at one axial end, in particular at the end facing away from the unslotted part.

Optionally, the nut further comprises a self-locking means, e.g. a weakened part (e.g. by locally thinner material), arranged in the region of the inner thread and adapted to provide a self-locking torque. The self-locking means may be (in particular elastically) deformed by applying a torque to the tool interface when mounting the nut on a bolt. The self-locking means may be a portion of the unslotted part. In this way, the nut can provide a second method of maintaining locking of the nut to the bolt in addition to the use of the pin.

Optionally, the weakened part is arranged between the tool interface and the slotted part. -4 -

The nut may be a castellated nut. The nut may be a front mount nut.

Optionally, the slotted part is not threaded. The inner thread may be exclusively arranged at the unslotted part. By this it may be ensured that the bolt engaged by the nut is not loaded above a (e.g. cross-drilled) pin hole. The slotted part may also comprise no outer thread.

The slotted part may have a circular-cylindrical outer and/or inner shape.

A set may be provided that comprises a nut according to any embodiment described herein, and a pin that fits through two opposite slots of the nut and/or a bolt.

According to an aspect there is provided a gas turbine, in particular for an aircraft, comprising at least one nut according to any of the preceding claims.

The gas turbine may be an engine adapted for an aircraft. The gas turbine engine may comprise an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor (the core shaft and the compressor may be the shaft and the compressor referred to above, or may be another shaft and/or another compressor of the gas turbine engine); a fan located upstream of the engine core, the fan comprising a plurality of fan blades; and a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft.

Alternatively, the gas turbine is a static gas turbine.

The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and/or combined with any other feature or parameter described herein.

Embodiments will now be described by way of example only, with reference to the Figures, in which: -5 -Figures 1A-1D are views of an embodiment of a nut for fixing one part to another, having a slotted part with closed slots and a weakened part; are views of an embodiment of a nut for fixing one part to another, having a slotted part with closed slots and a weakened part; Figures 2A-2C Figures 20 and 2E show two possible locking positions of the nut according to Figures 2A-2C on a bolt; Figures 3A-3C are views of an embodiment of a nut for fixing one part to another having a slotted part with closed slots; Figures 3D and 3E show two possible locking positions of the nut according to Figures 3A-3C on a bolt, Figures 4A-4C are views of an embodiment of a nut for fixing one part to another, having a slotted part and a tool interface at the slotted part; Figures 40 and 4E show two possible locking positions of the nut according to Figures 4A-4C on a bolt, Figures 5A-5C are views of an embodiment of a nut for fixing one part to another, having a slotted part with slots open at one longitudinal end; Figures 50 and 5E show two possible locking positions of the nut according to Figures 5A-5C on a bolt, and Figure 6 is a sectional side view of a gas turbine engine. -6 -

Figure 1A shows a side view of a nut 100A for fixing one part to another. Figure 1B shows a top view thereof. Figure 1C shows a partly sectional view of the nut 100A. Figure 1D shows a sectional view of the nut 100A at the plane J-J as indicated in Figure 1C.

The nut 100A has an inner thread 101 to be screwed on a corresponding bolt. The inner thread 101 defines a thread axis X. The thread axis is the central axis of the thread, around which the inner thread 101 extends.

The nut 100A further comprises a slotted part 102 and an unslotted part 104 (see particularly Figure 1C). The slotted part comprises a plurality of slots 103, in the present example 6 slots 103. The slots 103 each have the same shape, in particular the same slot length S (in axial direction, see particularly Figures 1A and 1C) and the same slot width K (see particularly Figure 1D). Each two neighbouring slots 103 are offset to one another by 60 degrees. Each two slots 103 are arranged at opposite sides of the nut 100A, offset by 180 degrees with respect to one another. A pin may be inserted through both opposing slots 103 and a hole in a bolt therebetween in order to lock the nut 100A against any further rotation on the bolt.

The slots 103 extend in axial direction (i.e., parallel to the thread axis X) from a first end 107 to a second end 108. The distance between the fist end 107 and the second end 108 of each of the slots 103 defines the slot length S. The slot length S is designed such as to safely receive a pin at different axial positions. By this, the nut 100A can be used with different bolt lengths and/or with the same bolt length, for different thicknesses of parts to be fixed by means of the nut 100A and the bolt.

At least one first end 107 defines (in the example according to Figures 1A-1D the first ends 107 of all slots 103 define) a plane that is orthogonal to the thread axis X and at which the unslotted part 104 is connected to the slotted part 102. In axial direction, the nut 100A has a first end 105 and a second end 106 opposite the first end 105. The distance of the first and second ends 105, 106 defines the total axial length H of the nut 100A. The unslotted part 104 is defined as that part of the nut 100A which extends from the first end 105 of the nut 100A to the first ends 107 of the slots 103 (i.e., to the plane defined thereby). The slotted part 102 extends from the first ends 107 of the slots 103 (i.e., from the plane defined thereby) to the second end 106 of the nut 100A.

The slotted part 102 further comprises a bridging section 111. The bridging section 111 connects strips of material arranged between each two slots 103. The bridging section 111 has a circular-cylindrical shape. The bridging section 111 may stiffen the strips of material and may reduce induced vibrations of the strips of material. As can be seen particularly in Figures 1A and 1C, the bridging section 111 defines the second end 106 of the nut 100A. In other words, the bridging section 111 is arranged at the free end of the nut 100A.

The slotted part 102 has an outer diameter G. The nut 100A is a castellated nut. The slotted part 102 may also be referred to as castellated part.

The inner thread 101 is arranged at the unslotted part 104. The inner thread 101 does not extend along the slotted part 102. In the example according to Figures 1A to 1D, the inner thread 101 extends in axial direction over the entire length of the unslotted part 104. In other words, the inner thread 101 ends at the plane defined by the first slot ends 107.

The nut 100A has a tool interface 109. The tool interface 109 has a tool interface diameter W. Here, the tool interface 109 is a hexagonal portion that may be engaged by a corresponding wrench, and the tool interface diameter W is measured as the distance of two opposing, parallel surfaces of the hexagon. The tool interface diameter may correspond to that of a 5/16 nut while a thread size T of the inner thread 101 may be 0.25 inch.

The tool interface 109 is formed at the unslotted part 104. By this the slotted part 102 is not torqued and, optionally, the material thickness of the slotted part 102 may be kept low for a low weight of the nut 100A. -8 -

The unslotted part 104 further comprises a weakened part 110. At the weakened part 110 the material thickness of the nut 100A is reduced with respect to adjacent portions, in particular with respect to adjacent portions at both sides of the weakened part 110 in axial direction. The weakened part 110 is formed as a ring-shaped groove. The weakened part 110 may be an out of round crimped portion. The weakened part 110 may be elastically deformed when applying torque to the nut 100A. The weakened part 110 provides a reusable self-locking performance of the nut 100A. Thus, the weakened part 100 may serve as another locking feature in addition to the slots 103 that may cooperate with a pin. The weakened part 110 has an axial length Q. By means of the weakened part 110, it is possible to provide a double locked self-locking nut.

Next, dimensions of three possible variants of the nut 100A will be given in the following table 1 by way of example.

Dimension [unit] Variant 1 Variant 2 Variant 3 Total axial length H [mm] 17.90 18.00 18.10 Thread length L [mm] 7.85 8.00 8.15 Thread size T [inches] / [mm] 0.25 /6.35 0.25 / 6.35 0.25 / 6.35 Tool interface diameter W [mm] 9.32 9.83 9.83 Axial length of slotted part Y [mm] 10.05 10.00 9.95 Slot length S [mm] 8.35 8.50 8.65 Slot width K [mm] 1.79 2.54 2.54 Axial length of weakened part Q [mm] 0.85 1.05 1.25 Tool interface length M [mm] 3.50 3.50 3.50 Diameter of slotted part G [mm] 8.80 8.80 8.80 Table 1: Examples of dimensions Another embodiment of the nut 100A has dimensions which are within the ranges defined by variant 1 and variant 3.

As can be seen in particular from table 1, the slot length S is equal to or larger than the thread size T for variants 1-3. Furthermore, the slot length S is equal to or larger than 2 times the slot width K. Also, the slot length S is equal to or larger than 80%, in -9 -particular 90% of the diameter G of the slotted part 102, e.g., S = (1 +/-0.2)G. The nut 100A may fulfil one, several or all of these conditions.

In the following table, several relative dimensions are given. All values are given in 5 percentages.

Relative dimension Variant 1 Variant 2 Variant 3 Y/H 56 56 55 Y/W 108 102 101 (W-T)/Y 30 35 35 S/H 47 47 48 S/VV 90 86 88 (W-T)/S 36 41 40 Table 2: Relative dimensions As can be seen in particular from table 2, in all example variants 1-3, the axial length Y of the slotted part 102 is equal to or larger than the tool interface diameter W, and the slot length S is larger than 50% of the tool interface diameter W. The nut 100A may fulfil one or all of these conditions, optionally in combination with the conditions mentioned with reference to table 1.

It will be appreciated that the absolute dimensions of the nut 100A may be varied, maintaining the conditions mentioned with reference to tables 1 and/or 2. As examples, the nut 100 according to variants 1-3 may be scaled by a factor of 0.5, 2, 5 or 10 or by a factor between 0.5 and 10.

Figures 2A to 2C show an embodiment of a nut 100B similar to the nut 100A shown in Figures 1A to 1D, only having a shorter tool interface length M of 2.50 mm. Figure 2A further shows a pin 200 in the form of a split or cotter pin. The nut 200B and the pin 200 together form a set for securing parts to one another.

Figure 2D shows a bolt 300 with an outer thread onto which the nut 100B is screwed. The bolt has a hole 301 at its threaded part. By aligning two of the slots 103 of the nut 100B with the ends of the hole 301, the pin 20 may be inserted therethrough for securing the nut 100B on the bolt 300.

-10 -While Figure 2D shows the nut 100B arranged so that the hole 301 is located at the first ends 107 of the slots 103, Figure 2E shows the nut 100B arranged so that the hole 301 is located at the second ends 108 of the slots 103. The distance of the first end 105 of the nut 100B to a head 302 of the bolt 300 defines the total thickness of components fixed to one another by means of the set of the nut 100B, the bolt 300 and the pin 200. The position of the nut 100B shown in Figure 2D corresponds to the maximal thickness and the position of the nut 100B shown in Figure 2E corresponds to the minimal thickness.

Figures 3A to 3E show a nut 100C which is similar to the nut 100B shown in Figures 2A-2E, but has no weakened part 110. The tool interface 109 is correspondingly relatively large in axial direction for an easy access with a wrench.

Figures 4A to 4E show a nut 100D similar to the nuts 100A-100C according to Figures 1A-3E. In contrast thereto, the nut 100D according to Figures 4A-4E has the tool interface 109 located at the slotted part 102. The tool interface 109 has a hexagonal outer shape for being engaged by a wrench. This nut 100D may be easily accessible with a wrench in narrow surroundings.

At least portions of the slotted part 102 have a larger material thickness than at least a portion of the unslotted part 104.

The unslotted part 104 has a circular-cylindrical outer shape on a majority of its axial extension. The section having a circular-cylindrical outer shape may serve for self-locking the nut 100D on the bolt 300 by deformation in a re-usable manner.

Figures 5A to 5E show a nut 100E similar to the nuts 100A-100D according to Figures 1A-4E. In contrast thereto, however, the nut 100E according to Figures 5A- 5E has no bridging section 111. The slots 103 of the nut 100E are not closed at both ends 107, 108. Instead, the second ends 108 of the slots 103 are open. Hereby, the mass of the nut 100E may be reduced. Further, the nut 100E has depressions at the tool interface (which is located at the unslotted part 104) to further reduce the mass of the nut 100E.

The nuts 100A-100E are reusable.

Figure 6 illustrates a gas turbine engine 10 having a principal rotational axis 9. The 5 engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10A comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and 10 a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10A and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an optional epicyclic gearbox 30.

In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27. The fan 23 generally provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

The gas turbine engine 10 comprises a plurality of nuts 100A-100E according to one or more embodiments described herein. By this, the same type of nut 100A-100E may be used with the same type of bolt 300 at different locations where differently thick components need to be fixed to one another. Therefore, a lower number of different bolt lengths need to be kept in storage for manufacturing the gas turbine engine 10 (or another machine). Further, a change of bolt length at a given location can be serviced with the same nut 100A-100E. Also a possible mix-up of different bolts 300 during installation of the gas turbine engine 10 (or another device) may be avoided.

-12 -It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

Claims

-13 -CLAIMS1 A nut (100A-100E) for fixing parts to one another, comprising an inner thread (101) that defines an axis (X), a tool interface (109) having a tool interface diameter (W), and a slotted part (102) that has a plurality of elongate slots (103) and extends from an axial end (107) of at least one of the slots (103) to an axial end (106) of the nut (100A-100E) with an axial length (Y), wherein each of the slots (103) is adapted for receiving a pin (200) and has a slot length (S), wherein the axial length (Y) of the slotted part (102) is equal to or larger than the tool interface diameter (W) and/or the slot length (S) is larger than 50% of the tool interface diameter (W).
The nut (100A-100E) according to claim 1, wherein the slot length (S) is about 90% of the tool interface diameter (W).
The nut (100A-100E) according to claim 1 or 2, further comprising an unslotted part (104) extending from another axial end (105) of the nut (100A-100E) to the slotted part (102).
A nut (100A-100E) for fixing parts to one another, in particular according to any of the preceding claims, comprising an inner thread (101) with a thread size (T) and an axial thread length (L), and a slotted part (102) with a plurality of elongate slots (103) adapted for receiving a pin (200) and having a slot width (K) and a slot length (S), wherein the slot length (S) is equal to or larger than: the thread size (T) and/or 2 times the slot width (K) and/or 80%, in particular 90% of a diameter (G) of the slotted pad (102).
The nut (100A-100E) according to claim 4, wherein the slot length (S) is 3 times the slot width (K) or more.
The nut (100A-100E) according to claim 4 or 5, wherein the slot length (S) measures 1.0 to 2.0 times the thread size (T), in particular 1.1 to 1.5 times the thread size (T), more particularly 1.2 to 1.4 times the thread size (T). 2. 3. 4. 5. 6.
-14 - 7. The nut (100A-100E) according to any of the preceding claims, having a total axial length (H), wherein each of the slots (103) has a slot length (S) measuring 0.4 to 0.7, in particular 0.45 to 0.65, of the total axial length (H).
8. The nut (100A-100E) according to any of the preceding claims, wherein all of the slots (103) have the same slot length (S).
9. The nut (100A-100E) according to any of the preceding claims, wherein pairs of slots (103) are arranged opposite to one another so that a pin (200) may be pushed through both slots (103) of the pair.
10. The nut (100A-100E) according to any of the preceding claims, wherein the slots (103) are oriented parallel to the thread axis (X) of the inner thread (101).
11. The nut (100A-100E) according to any of the preceding claims, wherein the slots (103) are closed at both axial ends (107, 108).
12. The nut (100A-100E) according to any of claims 1 to 10, wherein the slots (103) are open at one axial end (108).
13. The nut (100A; 100B) according to any of the preceding claims, further comprising a self-locking means, in particular in the form of a weakened part (110), in the region of the inner thread (101) adapted to provide a self-locking torque.
14. The nut (100A-100E) according claim 13, wherein the weakened part (110) is arranged between a tool interface (109) and the slotted part (102).
15. The nut (100A-100E) according to any of the preceding claims, wherein the nut (100A-100E) is a castellated nut.
16. The nut (100A-100E) according to any of the preceding claims, wherein the slotted part (102) is not threaded.
17. The nut (100A-100E) according to any of the preceding claims, wherein the slotted part (102) has a circular-cylindrical outer shape.
18. A gas turbine (10), in particular for an aircraft, comprising at least one nut (100A- 100E) according to any of the preceding claims.