GB2617376A

GB2617376A - Borescope

Info

Publication number: GB2617376A
Application number: GB2205075.1A
Authority: GB
Inventors: K Sims Brett; Yan Dawei; J Walker Ben; James Barron Thomas
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2023-10-11
Also published as: GB202205075D0

Abstract

A borescope for delivery of a tool has an elongate article with an axis and flexure slots 48 spaced axially between adjacent tube portions 50. Each slot has a ligament portion 52 unitarily connecting adjacent tube portions, the ligament portion and tube portions being formed from the same piece. The ligament portions may be along a perimeter width w1,w2 of the apparatus. This width or a perimeter position may be different for the ligament portion of a first flexure slot compared to that of a second flexure slot. The flexure slot may be orthogonal or oblique to the major axis through the elongate article. The flexure slot may include a bulbous portion 80 adjacent to the ligament portion and a straight or divergent portion 82 extending from the bulbous portion. The straight or divergent portions may include features on axially opposing sides 84 of the straight or divergent portions which are adapted to contact, or lock together after contact, upon deflection. The elongate article may include a superelastic and/or a shape memory alloy. The borescope is for the inspection of the internal parts of machines such as turbine and compressor components of jet engines and oil and gas processing equipment.

Description

BORESCOPE

The present disclosure concerns apparatus for delivery of a tool to a location and in particular, although not exclusively, relevant to an arm for a borescope used for the inspection of the internal parts of machines such as, for example the turbine and compressor components of jet engines, oil and gas processing equipment, etc. Borescopes are known which deliver tools such as sensors, machining tools, cameras, etc. to the desired location. These devices permit inspection and/or treatment of internal components without having to physically dismantle the device that is being inspected or treated. The borescopes have a proximal end that is located close to an actuator which controls the delivery of the tool and a distal end that carries the sensor or tool.

Turbomachinery may be provided with ports extending through a casing through which the borescope may be inserted. The path from the port to the desired location is often known which allows the route to be predetermined. The path is often convoluted requiring the delivery arm to twist, curve or deflect as it is being inserted into the turbomachinery. In a known delivery device, such as that described in GB2425764, a tool is delivered along a path determined by a cam and follower arrangement with a number of internal wires that are tensioned selectively and which determine how the borescope flexes.

It is an object of the present disclosure to seek to provide an improved apparatus for delivery of tools.

According to one aspect of the present disclosure there is provided borescope apparatus for delivery of a tool, the apparatus comprising an elongate article having an axis and comprising a plurality of flexure slots spaced axially between adjacent tube portions, wherein each slot has a ligament portion unitarily connecting the adjacent tube portions.

It will be appreciated that the term "tool" used in this specification includes any item that is of use, including: a camera, fibre optic, optical device, an infra red or ultrasound inspection tool, other sensors, a mechanical tool such as a cutter or driving tool and a welding tool and so on.

The tool may be passive or require an additional power source to supply, for example, electricity. The power source may be located at the distal end as a battery or remote from the distal end where the supply to the distal end is through a cable or wire. The cable or wire may pass through the elongate article.

The tool may be attached to the distal end by any appropriate means including, for example, magnets, bayonette fitting, screw fitting, hook and loop fasteners, adhesive. The attachment may be permanent or temporary.

The ligament portions may be provided by a perimeteral width of the apparatus. The perimeteral width may vary along the length of the ligament. The perimeteral width of a ligament portion of a first flexure slot may be different to the perimeteral width of a ligament portion of a second flexure slot.

The tube portions may have a circular cross-section with the perimeteral width of the ligament being an arc. The, or each, arc of the ligament may extend no more than 120° of the perimeter. The, or each, arc of the ligament may extend no more than 90° of the perimeter. The, or each, arc of the ligament may extend no more than 60° of the perimeter. The, or each, arc of the ligament may extend no more than 45° of the perimeter. The, or each, arc of the ligament may extend no less than 22.5° of the perimeter. The, or each, arc of the ligament may extend no less than 35° of the perimeter.

The cross-section of the tube portions may be have a different cross-sectional shape with at least one axis of symmetry e.g. triangular, square, pentagonal, hexagonal, etc. With these shapes the ligament portion may extend less than the length of one of the sides of the geometric shape. The ligament portion may extend over two or more adjacent sides of the geometric shape.

The ligament portions are less rigid than the tube portions which means that upon application of a tensile force along the axis of the apparatus the borescope will deflect at the flexure slots without causing bending of the respective tube portions.

By tensile force it is meant that a force is applied to the elongate member in the axial direction. The force imparts an eccentric axial load which creates a bending moment in the elongate article. Parts of the elongate article may be in tension and other parts are in compression once bending has occurred.

Ligaments of different widths require different levels of tensile force in order to induce bending at the flexure slot. By selecting appropriate widths along the axial extent of the borescope arm it is possible to induce non-axially-sequential bending of the borescope arm. This can facilitate delivery of the tool on the distal end of the arm without excess complication of the borescope.

The circumferential position of a first flexure slot may be different to the circumferential position of a second flexure slot. By arranging the slots in this way it is possible to a twist, or spiral deflection within the apparatus upon application of the tensile load along the length of the apparatus, The flexure slot may extend orthogonally or obliquely to the major axis through the elongate article. The flexure slot may be symmetrical along an axial plane of symmetry. The flexure slot may be symmetrical along an orthogonal plane of symmetry.

The flexure slot may comprise a bulbous portion adjacent the ligament portion and a straight, or divergent portion extending from the bulbous portion.

The straight or divergent portions may comprise features on axially opposing sides 30 of the straight or divergent portions. The features may be adapted to contact upon deflection of the article at the flexure slot.

The contact may provide a stop to further deflection. The contact may provide a locking function which provides a torsional stiffness between the tube portions.

The elongate article may be made of an appropriate metal or plastic. The elongate article may be made of a flexible metal such as an alloy that exhibits superelasticity and /or shape memory properties. Superelasticity is the ability for the metal to undergo large deformations and immediately return to its undeformed shape upon removal of the external load. A particularly preferred alloy is Nickel titanium (Nitinol).

The apparatus may further comprise an actuator that applies axial tension to the 10 elongate article, the tension causing deflection of the apparatus at the flexure slots.

The actuator may comprise a tensioning element such as a wire, strap, band, rod or other elongate member connected between an actuating device located at a proximal end of the article and a fixing point located at a distal end of the article. The tensioning element may be electrically conducting and provide power to the distal end of the elongate article.

The apparatus may have multiple tensioning elements secured to the apparatus 20 at varying positions along the length of the borescope. The tensioning elements may be individually actuated to provide greater control of how the borescope arm deflects.

The apparatus may be used to inspect a component in a gas turbine engine by inserting the elongate article through a housing of the engine and advancing the distal region of the elongate article and changing the shape of the elongate article to bring an inspection tool into the region of the engine that is to be inspected, carrying out the inspection and then retracting the elongate article through the housing.

The component may be in the intake, transmission, compressor, combustor, or exhaust sections of the engine. The component may be in the air system or the oil system. The component may be a blade, vane, liner, combustor, sealing feature, casing or any other appropriate component.

The apparatus may be used to inspect for cracks, nicks, damage, coating failures, debonding or any other feature The apparatus may be used in a mechanical device other than a gas turbine engine. The mechanical device may be in the oil or gas industry, power generation industry, transport industry, etc. The mechanical device may have moving parts that e.g. translate or rotate, and / or it may contain static components.

The method may comprise advancing the distal region and changing the shape such that the obstacles are not contacted during advancement or retraction of the elongate article.

The method may comprise attaching the instrument, or borescope apparatus to 15 the housing. The method may comprise inspecting a plurality of components within an engine.

The method may comprise inspecting the component and determining whether replacement or repair is required or whether further inspection is required. The results of the inspection may be compared with previous inspections to determine whether there has been a change in condition and / or the rate of change. The timing of any subsequent inspection or treatment may be scheduled.

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

Embodiments will now be described by way of example only, with reference to the Figures, in which: Figure 1 is a sectional side view of a gas turbine engine; Figure 2 is a perspective view of the borescope actuator and arm mounted to an engine casing; Figure 3 is a schematic of the distal end of the borescope arm inserted to inspect a blade within the engine casing of Figure 2; Figure 4 depicts an exemplary borescope arm in an unactuated form; Figure 5 depicts the borescope arm of Figure 4 in an actuated form; Figure 6a to 6d depict a schematic process of insertion of a borescope arm in order to inspect a component; Figure 7 depicts an embodiment of the borescope arm with multiple tensioning wires; Figure 8 depicts flexure slots according to an aspect of the invention; Figure 9 depicts alternative, exemplary, attachment features for tensioning wires within the borescope arm; Figure 10a to 10d depict alternative embodiments of flexure slots.

With reference to Figure 1, a gas turbine engine is generally indicated at 10, having a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 12, a propulsive fan 13, an intermediate pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, an intermediate pressure turbine 18, a low-pressure turbine 19 and an exhaust nozzle 20. A nacelle 21 generally surrounds the engine 10 and defines both the intake 12 and the exhaust nozzle 20.

The gas turbine engine 10 works in the conventional manner so that air entering the intake 12 is accelerated by the fan 13 to produce two air flows: a first air flow into the intermediate pressure compressor 14 and a second air flow which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 14 compresses the air flow directed into it before delivering that air to 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 combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 17, 18, 19 before being exhausted through the nozzle 20 to provide additional propulsive thrust.

The high 17, intermediate 18 and low 19 pressure turbines drive respectively the high pressure compressor 15, intermediate pressure compressor 14 and fan 13, each by suitable interconnecting shaft.

As shown in Figures 2 and 3, the tool 32 is securely attached to the engine housing 40 by bolts 38. The tool is advanced within the housing to arrive, eventually, at the position shown in Figure 3. The tool can be manoeuvred through a tortuous space, without touching any of the parts within the housing, to bring a tool (such as an ultrasonic sensor) 24 that is secured to the distal end 46 of the borescope into the crutch of a turbine blade 14. Wires (not shown) connect and power the sensor. Any cracks due to fatigue at the forward end of the turbine blade are picked up by the sensor and transmitted to a control panel (not shown) The sensor and the distal end of the elongate article can then be withdrawn. The engine is then indexed round to present the next blade 14 and the operation repeated. In this way all turbine blades can be quickly and easily inspected for signs of fatigue with the control panel being able to identify any blades in need of replacement.

The elongate article is depicted in Figures 4 to 6 in its relaxed position and its deployed position under a tensile load applied preferably by an internal tensioning element such as a wire. In Figure 4 the article 40 has a proximal end 42 and an actuator 44 aligned therewith. The distal end 46 of the article has a sensor 24. The article is made of a flexible metal such as an alloy that exhibits superelasticity and preferably shape memory properties. Superelasticity is the ability for the metal to undergo large deformations and immediately return to its undeformed shape upon removal of the external load. A particularly preferred alloy is Nickel titanium (Nitinol) The article has an axis and a plurality of flexure slots 48 spaced axially along the axis between adjacent tube portions 50, wherein each slot has a ligament portion 52 unitarily connecting the adjacent tube portions. Unitarily means that the adjacent tube portions and ligament portion is formed of a single piece and that the axially spaced flexure slots are formed by material removal.

A wire (not shown) is located within the article and fixed at the distal end 46 and connected to the actuator 44 such that when the actuator is operated a tensive load is applied along the axis of the article. Operation of the actuator may be effected by any appropriate means including physical, mechanical or electrical.

As shown in Figure 5 the tensive load induces deflection of the article at each of the flexure slots 48. As will be described later each of the flexure slots may be configured differently such that they deflect in a non axially-sequential manner.

Figure 6 depicts how the borescope may be used to deliver a sensor to component 60 through a tortuous path. The path comprises obstacles 62, usually other components of an engine, which prevent direct, linear, delivery of the sensor to the component. The borescope (Fig. 6A) in this example contains two flexure slots 48a, 48b though a greater number is preferable as it permits greater control over the delivery of the distal end 46. On application of the tensive load, flexure slot 48a is the first to deflect causing the borescope article, or arm, to bend once it has passed a first obstacle (Fig. 6B). The arm is indexed further (Fig. 6C) before a greater tensive load is applied to deflect the distal end further (Fig 6D). Whilst this is achieved with one wire extending within the borescope arm it is possible to utilise multiple wires that can be tensioned and relaxed independently to create even greater control over the borescope arm. In this arrangement the multiple wires should be fixed to the borescope arm at different positions along the axial length. As shown in Fig. 7, applying maximum tensive loads Ti T2 and T3 through actuation of wires 66a, 66b and 66c allow additional maximum tensive load values T4 and T5 to be applied.

Figure 8 depicts the structure of the borescope arm in greater detail and the exemplary flexure slots 48 provided within the arm. The arm is of unitary construction and provided by a tube with a circular perimeter. The tube has a plurality of axially spaced tube portions, where the perimeter of the tube is complete, separated by flexure slots 48 where a portion of the perimeter is removed to leave a ligament 52.

The amount of the perimeter that is removed determines the circumferential width (W1, W2) of the ligament and consequentially its resistance to deformation under applied tensile load. The circumferential width may be different, or the same for the, or each, or a plurality of the ligaments along the axial length of the tube. The resistance to deformation is also affected by the length of the ligament which may be different, or the same for the, or each, or a plurality of the ligaments along the axial length of the tube.

The circumferential position of the, or each, or a plurality of the ligaments may 10 vary along the axial length of the tube. It is the circumferential position that helps determine the direction in which the tube deflects at an individual flexure slot under applied tensile load.

Ligaments 52a, 52b, and 52c have substantially the same width which means that when a tensile load is applied in the axial direction L the tube will deflect at each respective flexure slot at substantially the same time. The slightly different circumferential positions of the ligaments will, however, cause deflection of the tube in different orthogonal directions at each flexure slot.

Once ligaments 52a, 52b and 52c have deflected, upon application of additional tensile load, the tube will deflect at the flexure slots aligned to respective ligaments 52d and 52e.

Upon removal of the tensile load, because the material of the tube exhibits shape 25 memory and/or superelasticity properties, the tube will resume its starting form. The resumption of the tube to its starting form will occur in the reverse order to which the deflection occurred.

Figure 9a depicts a top view and 9b a side view of the tube with a notch formation 70 at the distal end of the tube that provides a feature to which the actuating wire 66 may be secured and which prevents the wire slipping. The notch is preferable as it may be formed using the same mechanism as the flexure slots however, other solutions e.g. a dowel 72 extending between two opposing apertures could provide an alternative solution as would a longitudinal tab 74 formed within the wall of the tube that is bent into the tube and formed into a hook shape. These alternative features could find particular application where it is desirable to attach a tensioning element at a point that is not at the distal end.

The flexure slots are formed by any appropriate means either mechanical, chemical or from cutting e.g. by a laser. Laser cutting is preferred as it provides the greatest accuracy and flexibility in terms of slot shape and features. In relatively long borescopes, mechanical machining can induce vibration and chatter which reduces the accuracy of the flexure slots.

The embodiment of Figure 10a depicts a preferred shape of a flexure slot 48. The slot comprises a bulbous portion 80 adjacent the ligament portion 52 and narrower portion 82 extending away from the bulbous portion. The shape has been found to exhibit low stress upon deflection and the narrow portion can have opposing faces 84 which engage upon deflection of the flexure slot as shown in Figure 10b to limit the amount of deflection.

The opposing faces may also be shaped to lock together such that upon application of a rotational force to the tube the faces permit the transfer of higher levels of torque. This may be necessary when, for example, the distal end of the tube carries a fixed machining or polishing device. In this embodiment it may be desirable to form the flexure slot asymmetrically with one circumferentially extending edge of the bulbous portion adjacent one side of the ligament being further axially forward than the circumferentially extending edge of the bulbous portion adjacent the opposing side of the ligament. Alternatively, teeth or other keying features may be provided on each of the opposing faces 84.

Where a simpler form of flexure slot is desirable e.g. when the borescope tube may have a shorter life, or appropriate machining or laser cutting apparatus is not 30 available to form the more complex flexure slots, other embodiments of flexure slot may be used as shown in Figure 10c and d.

The "V" shaped slot of Figure 10c is the simplest to manufacture and has a low actuation threshold upon application of the tensile load. The tapered portion of Figure 10d permits a high deflection whilst the bulbous portion lowers the peak stress in the ligament It will be appreciated that the embodiments find particular application for on-wing 5 tin-situ applications. The ability to deliver a tool quickly, efficiently, repeatably and accurately to a desired location within an engine keeps the engine on wing for longer with minimal downtime of aircraft expected.

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

Claims 1. Borescope apparatus for delivery of a tool, the apparatus comprising an elongate article having an axis and comprising a plurality of flexure slots spaced 5 axially between adjacent tube portions, wherein each slot has a ligament portion unitarily connecting the adjacent tube portions.
2. Borescope apparatus according to claim 1, wherein the ligament portions are provided by a perimeteral width of the apparatus.
3. Borescope apparatus according to claim 2, wherein the perimeteral width of a ligament portion of a first flexure slot is different to the perimeteral width of a ligament portion of a second flexure slot.
4. Borescope apparatus according to claim 2 or claim 3, wherein the perimeteral position of a first flexure slot is different to the perimeteral position of a second flexure slot.
5. Borescope apparatus according to any preceding claim, wherein the flexure slot extends orthogonally or obliquely to the major axis through the elongate article.
6. Borescope apparatus according to any preceding claim, wherein the flexure 25 slot comprises a bulbous portion adjacent the ligament portion and a straight, or divergent portion extending from the bulbous portion.
7. Borescope apparatus according to claim 6, wherein the straight or divergent portions comprise features on axially opposing sides of straight or 30 divergent portions adapted to contact upon deflection of the article at the flexure slot.
8. Borescope apparatus according to claim 7, wherein the features on the opposing sides are adapted to lock together after contact
9. Borescope apparatus according to any preceding claim, wherein the apparatus further comprising an actuator that applies axial tension to the elongate article, the tension causing deflection of the apparatus at the flexure slots.
10. Borescope apparatus according to any preceding claim, wherein the elongate article comprises a superelastic and/or shape memory alloy
11. Borescope apparatus according to claim 9 or claim 10, wherein the actuator comprises a tensioning wire connected between an actuating device located at a proximal end of the article and a fixing point located at a distal end of the article.
12. Borescope apparatus according to claim 11 wherein the average perimeteral width of ligament portions in the half of the elongate article closest to 15 the distal end is less than the average width of the ligament portions in the half of the elongate article in the half of the elongate article closest to the distal end.
13. A method of operating Borescope apparatus according to any of claim 10 to claim 12, wherein the article deflects at the flexure slots when axial tension is 20 applied.
14. A method of operating Borescope apparatus according to claim 13, wherein the deflection at the flexure slots occurs sequentially from the narrowest ligament to the thickest.