GB2467734A

GB2467734A - Method of installing a component using adhesive to temporarily secure said component

Info

Publication number: GB2467734A
Application number: GB0902168A
Authority: GB
Inventors: Richard Paul Slocock
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2009-02-11
Filing date: 2009-02-11
Publication date: 2010-08-18
Also published as: GB0902168D0

Abstract

The method involves applying a hot-melt adhesive to a component to temporarily secure or protect the component as it is installed to its in use location within a device. The adhesive is then heated to above its melting point, which may be below 200°C, in order to release the installed component. The adhesive may be a glue which is applied as a liquid and then allowed to harden; the device may be a piston engine or a gas turbine engine and the component may be a sprung seal ring or one or more seal fins.

Description

METHOD OF INSTALLATION

This invention relates to a method of installing components to their "in use" location. It finds an application in the installation of sprung rings within a turbine engine.

Sprung rings such as piston rings are known to provide a good seal between two mating components. The sprung rings are open-ended rings with the ends facing each other and arranged such that the gap between the ends can increase or shorten to maintain the ring against one of the two mating components despite any movement of the mating components during transient conditions.

The components define an annular gap within which the seal is located. An in-sprung ring is designed to compress against the radially inner wall of the first mating component, whilst an out-sprung ring is designed to expand against the radially outer wall of the second mating component with the radially inner wall and the radially outer wall defining an annulus within which the ring is situated. Often grooves are provided in either the inner wall, outer wall or both into which the sprung ring is located in use.

Difficulties occur during assembly of the mating components and the sprung rings. By their very nature the inner circumference of the in-sprung ring in its unexpanded condition is less than the outer circumference of the radially inner wall and the outer circumference of the out-sprung ring in its uncompressed condition greater than the inner circumference of the radially outer wall. This means that there is a danger of damaging the radially inner wall as the in-sprung ring is moved over the radially inner wall to its operating position. For an out-sprung ring it is hard to locate the ring in its operating location.

It is an object of the present invention to seek to provide an improved ring seal and method of locating a ring seal.

According to a first aspect of the invention there is provided a method of installing a component to its use location having the steps of applying an adhesive to temporarily secure or protect a component, preseritiricj the component to its use location and releasing the component by heating the adhesive to a temperature above its melting point.

Preferably the adhesive is a hot-melt adhesive. The hot-melt adhesive may have a melting point below 2OOC.

Preferably the adhesive is applied to the component as a liquid and allowed to harden to temporarily secure or protect the component.

Preferably the use location is associated with a device which when operating reaches a temperature above the melting point of the adhesive. The device may be an engine which is preferably a gas turbine engine.

The component may a sprung seal ring or one or more seal fins or one or more vanes making up an assembly.

Preferably the method further comprises the step of operating the device till it reaches a temperature above the melting point of the adhesive.

According to a second aspect of the invention there is provided the use of a hot-melt adhesive applied to a component of a gas turbine engine to temporarily secure or protect the component as it is inserted into the gas turbine engine.

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 depicts an out-sprung ring in its sealing location Fig. 2 depicts the ends of an out-sprung ring at its largest operating diameter Fig. 3 depicts the ends of an out-sprung ring during application of an adhesive Figure 4 depicts the out-sprung ring constrained in its smallest diameter.

Figure 1 depicts an out-sprung ring seal 2 in a sealing location between two components -in this exemplary embodiment an inner case 6 and an outer case 4 in a turbine engine arranged coaxially around an axis 10, which is the centre line of the engine. The ring 2 is mounted within a slot on the inner case 6 which is formed by walls extending circumferentially around the outer surface of the inner case 6.

The spring is sprung against the inner surface of the outer casing 4 to provide a seal that inhibits passage of fluid through the annulus between the outer casing 4 and the inner casing 6 between the region marked A and the region marked B. The fluid in this embodiment is air but in other embodiments could be air or another gas or even a liquid such as water or oil, for example.

The inventive method used to facilitate mounting of the ring 4 between the two casings will be described with reference to Figures 2, 3 and 4. The ring at its largest operating out-sprung diameter is shown in Figure 2. The ends of the open ring are provided with an optional latching mechanism that helps to limit the maximum operating diameter of the ring. Each end of the ring has a thinner portion with a projection. In use the projections lie adjacent the thinner portion of the opposing end of the ring with the height of the thinner portion plus the opposing projection being equal to or less than the total height of the ring seal 2. The projections limit the ring expansion by catching on the opposing projection and limit ring contraction by abutting against the opposing full height portion of the ring.

During assembly of the two casings 4, 6 together the ring in secured in its smallest diameter. This means that its overall diameter is less than the internal diameter of the outer casing permitting the seal, which is in its channel on the inner casing, to be easily inserted inside the outer casing. An adhesive is applied to the thinner portion of the ring as depicted in Figure 3. The latch of the ring is engaged and the ring is compressed by hand to a smaller diameter. A small amount of adhesive is supplied to the ring latch gap and the ring maintained in its compressed state until the adhesive solidifies as shown in Figure 4. Alternatively, the latch of the ring may be sprung open such that the projections do not overlie the thinner portions and then placed within the groove on the inner casing. A bead of adhesive is applied from an appropriate source onto one of the thinner portions and the projections re-engaged and the ring contracted to compressed state and held in that state until the adhesive is solidified.

The adhesive, once solidified, forms a solid plug which holds the seal in its compressed state for extended periods of time.

The adhesive is selected such that it is removed by the application of heat either by localised heating e.g. through the use of a torch or other heating means or more preferably, where the components are heated in use, by the heat of the components when the device in which they are mounted is operated.

For the embodiment described here a particularly preferred adhesive is a hot melt adhesive that melts at around 100°C and has a flash point of around 300°C. The adhesive is preferably applied at temperatures between 130°C and 230°C and preferably around 200°C from a dispensing gun which contains an integral heater.

Because the ring seal is used within a high pressure compressor the operating temperature, at around 600°C, is significantly higher than the melting temperature and the flash point which means that following an initial test run of the engine the adhesive is completely removed leaving no residue. Because the adhesive melts at 100°C the ring is released to expand at this relatively low temperature and seals onto the inside surface of the outer casing. At the higher temperatures the adhesive is vapourised and removed from the engine by the flow of air passing through the gas turbine.

It will be appreciated that the invention describes an elegant way of temporarily securing components to other components during their assembly and then releasing them either by heating once assembled or automatically by operating the machine or device in which the components are located in use.

Although the invention has been described with respect to the use of hot-melt adhesives other adhesives that are solidified by mechanisms other than cooling, e.g. by application of UV light or other electromagnetic radiation, may be used provided that the solidified adhesive may be removed by the application of heat. The removal by the application of heat is desirable because it means that no additional chemicals, which may damage the engine, are required to dissolve the adhesive It will also be understood that the invention can also be applied to components other than sprung rings. For example, it is possible to secure individual vanes together in an assembly that are released in service through the melting of the adhesive used. In this invention the term component may be singular or plural which for the specific use in this paragraph means either the individual vanes or the assembly including the plurality of individual vanes.

The use of hot-melt adhesives in this way -to secure or protect components during their assembly into their in-use location and then releasing the components by removing the adhesive has very many applications. Some exemplary, but non limiting applications are given below.

For example, the adhesive may be used to provide a protective layer which may be applied over delicate parts to stop the parts being damaged if accidental contact is made. One exemplary application within the gas turbine industry is to coat seal fins on a high pressure compressor drum to stop damage during build.

The adhesive may be used to hold sprung rings open or closed as described above or may be used to temporarily secure a number of different components together whilst they are being assembled to their in-use position.

In addition, although the invention has been described with respect to use in a gas turbine the skilled person will know that it is equally applicable to use it in other industries especially where the component to which the adhesive is supplied is to be used at an operating temperature which is higher than the melting point of the adhesive and preferably higher than the flash point of the adhesive. Such exemplary applications are engines other than gas turbine engines, reactors, boilers etc.

Claims

CLAIMS1. A method of installing a component to its use location having the steps of applying an adhesive to temporarily secure or protect a component, presenting the component to its use location and releasing the component by heating the adhesive to a temperature above its melting point.
2. A method according to claim 1, wherein the adhesive is a hot-melt adhesive.
3. A method according to claim 1 or claim 2, wherein the hot-melt adhesive has a melting point below 200°C.
4. A method according to any preceding claim, wherein the adhesive is applied to the component as a liquid.
5. A method according to claim 4, wherein the adhesive is allowed to harden to temporarily secure or protect the component.
6. A method according to any preceding claim, wherein the use location is associated with a device which when operating reaches a temperature above the melting point of the adhesive.
7. A method according to claim 6, wherein the device is an engine.
8. A method according to claim 7, wherein the engine is a gas turbine engine.
9. A method according to claim 7 or claim 8, wherein the component is a sprung seal ring.
10. A method according to claim 8, wherein the component is one or more seal fins.
11. A method according to any one of claims 6 to 10, further comprising the step of operating the device till it reaches a temperature above the melting point of the adhesive.
12. A use of a hot-melt adhesive applied to a component of a gas turbine engine to temporarily secure or protect the component as it is inserted into the gas turbine engine.
13. A method substantially as herein before described with reference to the accompanying drawings.