GB2550855A

GB2550855A - Method of manufacture

Info

Publication number: GB2550855A
Application number: GB1609170.4A
Authority: GB
Inventors: Middlemas Luke; Stapleton David; Mellor Richard; Ryall Chris
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2016-05-25
Filing date: 2016-05-25
Publication date: 2017-12-06
Anticipated expiration: 2036-05-25
Also published as: GB201609170D0; GB2550855B

Abstract

A method of manufacturing a component comprises providing a base plate 32 and a plurality of carriers 36, reversibly connecting each carrier to the base plate using one or more mechanical fasteners 38, 40, forming a plurality of components using additive layer manufacturing and removing the carriers and integrally formed components from the base plate by releasing the fasteners. The mechanical fasteners may comprise bolts 40. The carriers may comprise location or positional features for location in a machine for post-processing. The surface of the carriers may be curved (136, figure 6) or planar. The shape of the carriers is preferably designed to minimize residual stresses in the component during the manufacturing process. A further method comprises providing a base plate and a carrier having a recess (448, figure 9), mechanically connecting the carrier to the base plate using one or more mechanical fasteners, positioning a sub-carrier (446) in the recess, using additive layer manufacturing to build material up onto the sub-component and removing the carrier and component from the base plate by releasing the fasteners.

Description

METHOD OF MANUFACTURE

TECHNICAL FIELD

The present disclosure concerns a method of additive layer manufacture and/or a component produced using said method of additive layer manufacture.

BACKGROUND

Additive layer manufacturing can be used to create parts from various materials. One type of additive layer manufacturing suitable for manufacturing metallic parts is powder bed additive layer manufacturing (ALM). In powder bed ALM a laser or electron beam is used to consolidate a powder so as to form a component. The geometry of the component may be specified in an electronic file such as a computer aided design (CAD) drawing. Powder bed methods include direct metal laser sintering (DMLS), electron beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), and selective laser sintering (SLS).

Generally, to produce a component using powder bed ALM, a consumable base plate is provided in the ALM machine. The component being manufactured by ALM is built on the base plate layer by layer, which means that once the final component is manufactured it is welded onto the base plate. The base plate is a thick plate and is provided so as to minimise stresses within the manufactured component.

Referring to Figure 1, often for manufacturing efficiency, multiple components 1010 are manufactured at the same time. This is done by building up multiple components on the same base plate 1032. Once the components are formed, the base plate is separated into sections 1034, i.e. one section per component. The base plate is cut into sections using, for example either wire electrode discharge machining or a mechanical horizontal bandsaw.

Whilst connected to the respective section of the base plate, the components are post processed, for example stress relieved, heat treated, and/or machined. Having the connected section of the base plate in place can help with controlling stresses in the component and can also be used for holding the component during the post processing. Once the desired post processing steps are complete, the component is removed from the respective section of base plate, often using wire electrode discharge machining (EDM). The base plate is then either re-machined to remove distortion or more generally is disposed of and is not reused.

SUMMARY

According to an aspect there is provided a method of manufacturing a component. The method comprises providing a base plate and providing a plurality of carriers. The method comprises reversibly connecting each carrier to the base plate using one or more mechanical fasteners. A plurality of components is formed using additive layer manufacturing, one component being formed on each carrier such that the components are integrally formed on the carriers. The method comprises removing the carriers and integrally formed components from the base plate by releasing the mechanical fasteners.

Reversibly connected is understood to refer to a connection that can be disconnected without requiring damage to the connected components. The carriers may also be considered to be removably and/or releasably connected.

The method may comprise post processing the components with the carrier attached. Post processing may comprise stress relieving, heat treatment, and/or machining.

The method may comprise removing the carrier from the component once post processing is complete. For example, using electrode discharge machining.

The carriers may be connected to the base plate such that the carriers are adjacent each other.

The carriers may be arranged to abut one another. The carriers may be arranged in a single row. Alternatively, the carriers may be arranged in two or more rows.

The mechanical (or releasable) fasteners may comprise bolts. That is, the method may comprise bolting the carriers to the base plate. In such embodiments, a pin may also be used.

The carrier may comprise a threaded recess for receiving a bolt. The base plate may comprise a hole (e.g. threaded or non-threaded). The method may comprise aligning the recess in one of the carriers with one of the holes in the base plate, and threadingly engaging a bolt with said carrier recess through said hole in the base plate.

In alternative embodiments, alternative mechanical fasteners may be used. For example, clamps, pins, snap-fit fasteners, and/or an anchor.

The carriers may have a regular shape.

The plurality of carriers may be the same shape and size. In such an example, the components manufactured may be the same shape and size.

The plurality of carriers may be made from the same material.

The method may comprise designing the shape of the carrier so as to minimise residual stresses in the component during the manufacturing process.

The method of design may use commonly used design techniques, such as computer simulation, finite element analysis, and/or modelling (e.g. numerical modelling).

The material of the carriers may be different to the material of the components.

The material of the base plate may be different to the material of the components. The material of the base plate may be the same material or a different material to the material of the carriers.

The carrier may comprise a recess and a sub-carrier may be provided in said recess. The component may be built on said sub-carrier. The sub-carrier may be connected to the recess, e.g. by welding. The sub-carrier may be made from a different material to the material of the remainder of the carrier. The shape of the sub-carrier may be regular, for example, the sub-carrier may be rectangular in plan-view and/or have a square or rectangular cross section. The sub-carrier may be made from the same material as the component.

The material of the component may be a metallic material, for example an aluminium or titanium alloy.

The carrier may comprise location and/or positional features for use in locating the carrier and the component in a machine for post processing. The location and/or positional features may be features additionally used to mechanically connect the connector to the base plate, e.g. one or more recesses for receiving a fastener.

The carriers may comprise one or more heating elements. The method may comprise heating and/or cooling a region of the carrier proximal to a surface of the carrier where the component is formed so as to control residual stresses in the component.

The carriers may be square, rectangular, curved, or l-shaped in plan-view. A surface of the carrier on which the component is formed may be curved or planar.

According to an aspect there is provided a method of repairing or manufacturing a component. The method comprises providing a base plate and providing a carrier having a recess. The method comprises mechanically connecting the carrier to the base plate using one or more mechanical fasteners. The method further comprises positioning a sub-component in the recess of the carrier and using additive layer manufacturing to build material up onto the sub-component to define the component. The method yet further comprises removing the carrier and component from the base plate by releasing the mechanical fasteners.

In an aspect there is provided a method of manufacturing a plurality of components, the method comprising providing a base plate and providing a plurality of carriers. The method comprises reversibly connecting each carrier to the base plate using one or more mechanical fasteners, wherein the carriers provide supports for the components to be manufactured. The method further comprises partially or fully forming a plurality of components using additive layer manufacturing; and removing the carriers from the base plate by releasing the mechanical fasteners.

For example, the carriers may support a member or subcomponent part onto which the remainder of the component is added using additive layer manufacturing. In further examples, the carriers may provide support to a component that is directly formed on the carrier.

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.

DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only, with reference to the Figures, in which:

Figure 1 is a perspective schematic of multiple components formed on a base plate using additive layer manufacturing;

Figure 2 is a sectional side view of a gas turbine engine;

Figure 3 is a schematic perspective view of a base plate and carriers on which a component can be formed;

Figure 4 is a schematic perspective view illustrating removal of a carrier and component from a base plate;

Figure 5 is a perspective view of a carrier;

Figures 6 to 8 are schematic perspective views of a base plate with alternative carriers attached;

Figure 9 is a perspective view of a further alternative carrier; and Figures 10 and 11 are further alternative examples of carriers.

DETAILED DESCRIPTION

With reference to Figure 2, 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 airflows: a first airflow 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 airflow 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.

Other gas turbine engines to which the present disclosure may be applied may have alternative configurations. By way of example such engines may have an alternative number of interconnecting shafts (e.g. two) and/or an alternative number of compressors and/or turbines. Further the engine may comprise a gearbox provided in the drive train from a turbine to a compressor and/or fan.

One or more of the components of a gas turbine engine may be manufactured using additive layer manufacturing (ALM), by way of example only, the combustor tiles of the combustion equipment 16 may be made using ALM. In particular powder bed ALM may be used. Powder bed ALM includes direct metal laser sintering (DMLS), electron beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), and selective laser sintering (SLS).

Referring to Figures 3 and 4, a method of manufacturing a plurality of components will now be described. A base plate 32 is provided. The base plate 32 may have a similar thickness to a conventional base plate, or alternatively may be made thinner than a conventional base plate. The base plate may be made from a material such as steel. A plurality of carriers 36 are connected to the base plate 32. In the present example the carriers are regular in shape. Also in this example, the carriers are all the same shape and size. In particular, each carrier 36 is a cuboid and is rectangular in plan-view and has a rectangular or square cross section. The carriers are made from a metal such as steel. In this example, the carriers are arranged in a row and are adjacent and abutting one another. It will be appreciated that the carriers define the substrate on which the components are built, and as such are made to the required thickness, which will be understood by the person skilled in the art. As mentioned above, the provision of the carriers means that it can be possible to reduce the thickness of the base plate.

The carriers 36 are connected to the base plate 32 using a mechanical fastener, in this example a pin 38 and a bolt 40 are used. The carrier is connected to the baseplate from an underside of the baseplate and the carrier. In the present example, a series of through holes are provided in the base plate. The carriers each include two recesses on their underside, one of which is threaded. To connect one of the carriers to the base plate, the recesses of the carrier are aligned with the respective holes of the baseplate. A pin is positioned in one of the holes and recesses (i.e. in the non-threaded recess and associated hole), and a bolt is provided in the other hole and the threaded recess. This is repeated until all the carriers are connected to the base plate.

Once all the carriers 36 are connected to the base plate 32, the components can be built on the carriers using additive layer manufacture (ALM), in particular powder bed ALM. The components are formed by a powder bed ALM machine building up the components layer by layer using a powder and a laser or electron beam to consolidate the powder. The powder is a metallic powder. In the case of the aerospace industry, the powder may be an aluminium or titanium alloy. As required, supports for the component may also be built and these can be removed at a later date. The method of forming a component using powder bed ALM is understood in the art and so will not be described in more detail here.

Once the components have been formed, the components will be integral with the carriers. The components and carriers are then removed from the base plate by removing the mechanical fastener, in this example the pin and the bolt. The components and carriers are then post processed. In alternative embodiments however, the components may be stress relieved before the carriers and components are removed from the base plate. The carriers and components will then be removed as described and are post processed.

The post processing operations may include heat treatment and/or machining. Referring to Figure 5, the carrier can be used as a locator and/or a fixture in the post processing operations. The position of the pin and the bolt recesses can be selected for optimal connection to the base plate but to locate the component on a machine and/or to attach a component to the machine. Example recesses in the component are indicated at 42 and 44 in Figure 5. In alternative embodiments, additional location and/or fixture points may be provided on the carrier.

The present inventors have found that using the conventional method of sectioning the substrate can influence the stresses within the component, and irregular and inconsistent shapes can cause highly stressed regions and contribute to component defects and scrap. Conversely, use of the method and carriers of the present disclosure improves management of component stresses and/or distortion which can reduce scrap and non-conformance.

As described, the carriers can include additional fixture and/or location points or the attachment features used to connect the carrier to the base plate (e.g. the recesses that receive the pin and bolt) may be used as fixture and/or location points. Having such fixture and/or location points means that machinery can be quickly set up for post processing, ease of automation of post processing can be facilitated, and accuracy of processes such as machining can be improved.

The method disclosed in the present application also removes the need to cut the baseplate into sections. As such, the described method can save on time and cost, and can remove the need to decontaminate components (in the conventional method, contamination can be caused when the baseplate is sectioned).

Furthermore, in the disclosed method, the base plate is reusable. The carriers may be reusable but may require some rework before use.

The geometry of the carriers can optimally be selected so as to minimise stresses in the final component. The geometry of the carrier can also be selected depending on the desired shape of the final component. For example, alternative carriers may be curved in plan-view as illustrated by carriers 136 in Figure 6, or may have an l-shape in plan-view as illustrated by carriers 236 in Figure 7. In the described examples, one row of carriers have been provided, but in alternative embodiments a plurality of rows of carriers may be provided, e.g. for smaller components, as illustrated by carriers 336 in Figure 8. When designing the geometry of the carrier standard modelling techniques may be used and optimisation may be performed to minimise stress. A further alternative carrier 436 is illustrated in Figure 9. The alternative carrier includes a sub-carrier 446 onto which the component 430 is built. The subcarrier is provided in a recess 448 of the remainder of the carrier, such that the overall profile of the carrier is a cuboid. The sub-carrier may be made of a different material to the remainder of the carrier, for example the sub carrier may be made from the same material as the component or a material that is functionally compatible with the material of the component. The carrier 436 is particularly useful when manufacturing small components. A yet further alternative carrier 536 is illustrated in Figure 10. The carrier 536 includes a channel 550 that extends through the carrier. In the present example, a pipe or tube 552 extends through the channel and joins one channel of the carrier with a further channel of the carrier or with a channel of an adjacent carrier. In the present example, the pipe oscillates through the plurality of adjacent carriers. The channels and the pipe or tube are provided proximal to a surface of the carrier 536 where the component part will be formed. The pipe or tube 552 defines heating elements. The heating elements can be used during the building of a component by ALM to either heat or cool the carrier. Heating or cooling the carrier can help to control the stresses produced during the ALM process.

Now referring to Figure 11, the carrier 636 may be used to support components that have already been partially formed before the ALM process. For example, the carriers may support simple geometry components where complex geometry features are to be added using ALM, or alternatively the carriers may support components that are intended for repair.

The examples provided have been described with reference to application in a gas turbine engine, but it will be appreciated that this technology is also applicable to other technical fields such as, by way of example only, nuclear and/or marine.

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 subcombinations of one or more features described herein.

Claims

1. A method of manufacturing a component, the method comprising: providing a base plate; providing a plurality of carriers; reversibly connecting each carrier to the base plate using one or more mechanical fasteners; forming a plurality of components using additive layer manufacturing, one component being formed on each carrier such that the components are integrally formed on the carriers; and removing the carriers and integrally formed components from the base plate by releasing the mechanical fasteners.

2. The method according to claim 1, comprising post processing the components with the carrier attached.

3. The method according to claim 2, comprising removing the carrier from the component once post processing is complete.

4. The method according to any one of the previous claims, wherein the carriers are connected to the base plate such that the carriers are adjacent each other.

5. The method according to any one of the previous claims, wherein the mechanical fasteners comprise bolts.

6. The method according to claim 5, wherein the carrier comprises a threaded recess for receiving a bolt, and the base plate comprises a hole, and the method comprises aligning the recess in one of the carriers with one of the holes in the base plate, and threadingly engaging a bolt with said carrier recess through said hole in the base plate.

7. The method according to any one of the previous claims, wherein the carriers have a regular shape.

8. The method according to any one of the previous clams, wherein the plurality of carriers are the same shape and size.

9. The method according to any one of the previous claims comprising designing the shape of the carrier so as to minimise residual stresses in the component during the manufacturing process.

10. The method according to any one of the previous claims, wherein the material of the carriers is different to the material of the components.

11. The method according to any one of the previous claims, wherein the carrier comprises a recess, a sub-carrier is provided in said recess, and the component is built on said sub-carrier.

12. The method according to claim 11, wherein the sub-carrier is made from the same material as the component.

13. The method according to any one of the previous claims, wherein the carrier comprises location and/or positional features for use in locating the carrier and the component in a machine for post processing.

14. The method according to any one of the previous claims, wherein the carriers comprise one or more heating element, and the method comprises heating and/or cooling a region of the carrier proximal to a surface of the carrier where the component is formed so as to control residual stresses in the component.

15. The method according to any one of the previous claims, wherein the carriers are square, rectangular, curved, or l-shaped in plan-view.

16. The method according to any one of the previous claims, wherein a surface of the carrier on which the component is formed is curved or planar.

17. A method of repairing or manufacturing a component, the method comprising: providing a base plate; providing a carrier having a recess; mechanically connecting the carrier to the base plate using one or more mechanical fasteners; positioning a sub-component in the recess of the carrier; using additive layer manufacturing to build material up onto the subcomponent to define the component; and removing the carrier and component from the base plate by releasing the mechanical fasteners.

18. A method of manufacturing a plurality of components, the method comprising: providing a base plate; providing a plurality of carriers; reversibly connecting each carrier to the base plate using one or more mechanical fasteners, wherein the carriers provide supports for the components to be manufactured; partially or fully forming a plurality of components using additive layer manufacturing; and removing the carriers from the base plate by releasing the mechanical fasteners.