GB2583578A

GB2583578A - Manufacturing method and components manufactured using the method

Info

Publication number: GB2583578A
Application number: GB2004092.9A
Authority: GB
Inventors: Dewhirst Mike; John Henry Nicholas
Original assignee: Sst Tech Ltd
Current assignee: Sst Tech Ltd
Priority date: 2019-03-26
Filing date: 2020-03-20
Publication date: 2020-11-04
Also published as: GB202004092D0; GB201904128D0

Abstract

A component formed by a manufacturing method of providing a prefabricated base member 12, and undertaking an additive manufacturing process, e.g. powder bed additive layer manufacturing, to construct features 16 thereupon to form a component 10 comprising the base and constructed features, which may be made of the same material, e.g. Inconel. The base may be supported by a support device (24, figure 3) with a recess within which the base is located, e.g. secured. The upper face of the base may be coplanar with the support device. The base may be formed using a CNC machining process. The face where the features are formed on may be non-planar, e.g. recesses or projections, e.g. ribs or grooves. To form integral separate components, the base may be divided after multiple features have been formed on different regions thereon.

Description

Intellectual Property Office Application No. GII2004092.9 RTM Date:29 July 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document: Inconel Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo

MANUFACTURING METHOD AND COMPONENTS MANUFACTURED USING THE METHOD

This invention relates to a manufacturing method for use in the manufacture of metallic components, and to components manufactured using the method.

Traditionally, metallic components used in, for example, automotive applications and the like have been fabricated by being cast in approximately the desired shape followed by a finishing process, or by machining from a block of material. More recently, especially where components of a complex shape are required, additive manufacturing processes have been used. One additive manufacturing process or method in common use is an additive layer manufacturing method in which a thin layer of a powder material is laid upon a substrate carried by a support table and a laser is used to heat those parts of the layer that are to form part of the end component. Subsequently, another layer of powder material is laid over the first layer and the step of heating parts of the layer is repeated. During each heating step, the powder material is melted or partially melted and welds, adheres or otherwise bonds to adjacent material within the layer and to the material of the preceding layer. By repeating the process of laying down layers of powder and heating those parts of the layer that are to form part of the final component it will be appreciated that, over time, a complex product can be built up. After the process has been completed, it will be appreciated that the component is buried within a quantity of unheated powder material. The component is removed from the powder material and any required finishing processes are undertaken.

It is normal for the heating of the first layer or first few layers of the powder material to result in the component being, effectively, welded to the substrate. It will be appreciated, therefore, that the component needs to be cut or otherwise removed from the substrate. By way of example, a wire erosion process may be used to cut the component free from the substrate. After removal in this manner, a finishing process may need to be undertaken on the cut face of the component to form it to a required level of smoothness and flatness. Often, the substrate used in such an application is then disposed of as it is unsuitable for reuse.

The need to cut the component free of the substrate is not only time consuming and costly, but also leads to an increase in the production of waste material, all of which is undesirable.

Where the component being manufactured includes regions of relatively great wall thickness, then it has been found that the heating process and subsequent cooling can result in significant residual stresses within the component that can result in geometric distortions. As part of a finishing process, heat treatment to reduce such stresses may be required.

These post production steps can be time consuming to undertake, and so result in increased manufacturing costs.

It is an object of the invention to provide a manufacturing method, and associated products, in which at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

According to the present invention there is provided a manufacturing method comprising providing a prefabricated base member, and undertaking an additive manufacturing process to construct features upon the prefabricated base member to form a component of a desired form comprising the prefabricated base and the constructed features.

It will be appreciated that as the constructed features are formed onto the prefabricated base, rather than onto a sacrificial substrate, the features do not become welded, or the like, to such a substrate or to a support table or the like upon which the substrate is carried during the additive manufacturing process. Accordingly, the need to undertaking a cutting operation to remove the component from such a substrate is not required, and subsequent finishing operations are avoided or reduced. Manufacture is thus simplified, taking less time and being less costly. Waste may also be avoided or reduced.

Where the parts of the component of most significant wall thickness are defined by the prefabricated base, then issues associated with residual stresses may be avoided or reduced. Consequently, the need to undertake post production stress relieving operations may be avoided.

The base member includes a face upon which the features are formed, and the said surface is preferably of non-planar form. By way of example, a plurality of recesses may be formed therein and/or a plurality of projections may be formed thereon, cooperating with the material delivered by way of the additive manufacturing process. The cooperation achieved in this manner may enhance the bond between the base member and the features. By enhancing the bond in this manner, the end product may be better able to withstand loads arising from, for example, differential thermal expansion.

The recesses and/or projections may take the form of a series of ribs or grooves that may be, for example, straight, arcuate, circular or the like. It will be appreciated, however, that these represent just a few options and that the invention is not restricted in this regard.

Conveniently, the support table or the like is formed with a recess within which the prefabricated base is located. Preferably, the upper face of the prefabricated base, in such an arrangement, is substantially coplanar with the surface of the support table or the like.

Accordingly, a conventional additive layer manufacturing process of the powder bed type as outlined hereinbefore may be readily employed. The location of the prefabricated base within a suitably shaped recess provided in the support table or the like may also serve to ensure that the prefabricated base is properly positioned to allow the features to be built up thereon in the correct positions. Alternatively, or additionally, other techniques may be used to secure the prefabricated base in a desired position on the support table or the like. The support table or the like may be arranged to carry the prefabricated bases of several components, allowing several components to be fabricated using a single additive layer manufacturing process.

Whilst a powder bed additive layer manufacturing process may be used, it will be appreciated that the invention is not restricted in this regard and that other additive manufacturing approaches may be used.

The prefabricated base may be formed using a range of techniques. By way of example, it may be formed using a CNC machining process. It will be appreciated, however, that other techniques could be used.

The prefabricated base and the constructed features may be of the same material. By way of example, they may be of Inconel. It will be appreciated, however, that different materials may be used for the prefabricated base and the features.

According to a second aspect of the invention there is provided a manufacturing method comprising providing a prefabricated base member including a plurality of regions intended, in use, to form parts of a plurality of end products, and undertaking an additive manufacturing process to construct features upon each of the plurality of regions, undertaking a finishing process to separate the regions from one another to form a plurality of components desired forms, each comprising a region of the prefabricated base and the constructed features formed thereon.

In such an arrangement, the base member may be of relatively large dimensions, for example substantially covering a support table of an additive manufacturing device.

The base member may be machined, prior to undertaking the additive manufacturing process or after completion of the additive manufacturing process to form the regions thereof to a desired shape.

It will be appreciated that in this manner a number of components may be manufactured with improved efficiency.

As described hereinbefore, the face of the base member upon which the features are constructed, in use, may be of non-planar form, for example to enhance a bond between the base member and the features.

The invention further relates to a component comprising a prefabricated base member upon which features are constructed using an additive manufacturing process, manufactured using one of the methods defined hereinbefore.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a view illustrating a component manufactured in accordance with an embodiment of the invention; Figure 2 is a diagrammatic sectional view illustrating part of the component of Figure 1; Figure 3 is a diagrammatic representation illustrating part of the method of manufacture; Figure 4 illustrates a modification to the arrangement illustrated in Figures 1 to 3; and Figures 5 and 6 are views illustrating an alternative embodiment of the invention.

Referring firstly to Figures 1 to 3 of the accompanying drawings, a component 10 is illustrated comprising a base 12 including mountings 14 to allow it to be bolted or otherwise secured to other components, in use, and features 16 defining a tubular wall 18 and reinforcing ribs 20. In accordance with the invention the component 10 is manufactured by firstly fabricating the base 12, for example using a CNC machining process. In the arrangement illustrates the base 12 is formed to be of generally rectangular form with projections defining the mountings 14 at the corners thereof, the mountings 14 each being formed with an opening 14a that can receive, in use, a bolt or other fixing device. The base 12 is formed with a central opening 12a of substantially rectangular form, with rounded corners. Whilst this form of base 12 is illustrated, it will be appreciated that the invention is not restricted in this regard and that other shapes or forms of base may be used.

After prefabrication of the base 12, the base 12 is located within a correspondingly shaped recess 22 formed in a support device, for example in the form of a support table 24 or the like of a powder bed type additive layer manufacturing device. If desired, suitable fixings may be used to secure the base 12 in position upon the support table 24 or the like. The support table 24 or the like may be provided with a number of recesses 22, and a number of bases 12 may be provided thereon to allow fabrication of several components 10 in a single operation of the additive layer manufacturing device.

Once the base 12 has been positioned upon the support table 24 or the like, the additive layer manufacturing device may be used to lay down a thin layer 26 of a powder material onto the support table 24 or the like, over the prefabricated base 12, and a laser or other heating device used to heat those parts of the layer 26 which are to form part of the final component 10, causing the powder material in those parts of the layer 26 to melt or partially melt, becoming welded or otherwise adhered or bonded to adjacent parts of the layer 26 and to the base 12. After heating of all of the required parts of the layer 26, another thin layer 28 of powder material is laid down over the first layer 26, and the heating operation repeated to cause welding, adhering or bonding of the material in the required parts of the layer 28 to one another and to the material of the preceding layer 26. It will be appreciated that by repeatedly applying layers of powder material and selectively heating the material, the component 10 can be built up using standard additive manufacturing techniques.

After all of the required layers have been laid down and selectively heated, the component 10 can be removed from the support 24 and the unheated powder material. As the first layer 26 is welded or otherwise adhered to the base 12 which forms part of the final component 10, rather than to a sacrificial substrate, it will be appreciated that no cutting operation or the like is required to remove the component 10 from such a substrate. Consequently, costly post production finishing operations are reduced or avoided and material waste from the need to cut the component from a substrate is avoided.

If the component 10 were formed just using an additive layer manufacturing method then the thickness of the base part may give rise to significant residual stresses within the component due to inconsistent cooling and thermal contraction, with post production treatment being required to relieve such stresses. Such issues may be exacerbated through the need to form the base part of increased thickness to allow for the need to cut the component from the substrate in a conventional manufacturing process. In the arrangement of the invention, the need to perform such operations may be avoided as the parts of the component 10 formed by additive manufacturing are all of relatively thin walled form.

Another advantage of the arrangement of the invention is that, depending upon the application in which the invention is used, it may be possible to use bases 12 of a standard design in the fabrication of components 10 of a range of different forms, the features formed by additive layer manufacturing differing form one another. Economies of scale in relation to the production of the standard bases 12 may thus be gained.

In the arrangement illustrated, the base 12 and the wall 18 and ribs 20 are all of the same material. For example, they may all be of Inconel. It will be appreciated, however, that other materials may be used, and that there is no need for the base 12 to be of the same material as the wall 18 and ribs 20.

Figure 4 illustrates, diagrammatically, a modification to the embodiment described hereinbefore in which the base 12 is shaped so that the face 12b thereof upon which the features 16 are formed is of non-planar form. Specifically, in this embodiment, the face 12b of the base 12 is formed with a series of recesses 12c into which some of the powder material is delivered upon laying down of the thin layer 26, subsequent heating of the material delivered into the recesses 12c causing the features 16 to include parts integrally formed therewith that are located within the recesses 12c, forming a mechanical interlock with the base 12 and so enhancing the bond between the base 12 and the features 16. The recesses 12c may take the form of a series of discrete pockets, longer grooves, annular rings or a number of other forms.

Furthermore, whilst recesses 12c are illustrated, it will be appreciated that the invention is not restricted in this regard and alternatively, or additionally, a series of projections may be provided that upstand from the face 12b and project into the features 16, achieving substantially the same effect.

It will be appreciated that by enhancing the bond between the base 12 and the features 16, the component may be better able to withstand loads arising from, for example, differential thermal expansion between the materials of these parts of the component.

Figures 5 and 6 illustrate an alternative to the embodiments described hereinbefore and intended for use in the manufacture of multiple parts in a single manufacturing process. In the arrangement of Figures 5 and 6, the base 12 is of relatively large dimensions, for example covering substantially the entirety of the support table 24 or the like. Openings or the like may be formed therein to aid location and retention of the base 12 in the correct position upon the support table 24. The base 12 defines a plurality of base regions 12d, each of which is to form part of a respective completed component. In the arrangement shown, three such regions 12d are provided, side-by-side, but it will be appreciated that the invention is not restricted in this regard, and the layout of the regions 12d may be chosen to allow most efficient manufacturing of the parts, if desired.

Cutouts or openings 12e are preferably formed in the base 12, substantially surrounding the regions 12d, small legs 12f conveniently being retained to connect the regions 12d to the remainder of the base 12. It will be appreciated that, in such an arrangement, the presence of and shapes of the cutouts 12e define the boundaries of and the shapes and sizes of the regions 12d.

An additive manufacturing process is undertaken upon the base 12, and in particular upon the regions 12d thereof, for example in substantially the manner described therein, the additive manufacturing process being operable to form features 16 upon each of the regions 12d, such that each of the regions 12d and the associated features 16 formed thereon will go on to form a respective end product. The regions 12d may all be of the same shape and size as one another, as shown, with the features 16 being the same shape and size as one another to form a plurality of substantially identical components. However, this need not be the case and the regions 12d and/or features 16 may be of a range of shapes and sizes, to form components of a number of shapes and sizes in a single manufacturing operation, if desired. In this manner, manufacturing efficiencies may be achieved.

If desired, as described hereinbefore, the face of the base 12 may be shaped to be of non-planar form, to enhance a bond formed between the base 12 and the features 16.

After completion of the additive manufacturing process, a finishing operation is undertaken to separate the regions 12d from one another, resulting in the formation of a plurality of separate components. The finishing operation may comprise solely the step of separating the regions 12d from one another, cutting through the legs 12f, or may include additional steps, for example machining the regions 12d to desired shapes.

In a modification to the method described hereinbefore, rather than machining the base 12, prior to undertaking the additive manufacturing operation, to form the cutouts 12e partially separating the regions 12d from one another, and to form the regions 12d to substantially their desired final shapes and sizes, all of such machining may be undertaken after completion of the additive manufacturing operation.

Whilst the description and drawings are of an arrangement in which the base 12 is of a particular form, and the features 16 formed by additive manufacturing take the form of a wall 18 and ribs 20 of a particular shape, it will be appreciated that the invention is not restricted in this regard, but rather is applicable to components of a range of shapes, suitable for use in a wide range of applications.

Although specific embodiments of the invention are described herein, it will be appreciated that a wide range of modifications or alternations may be made to the arrangements described herein without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS: 1. A manufacturing method comprising providing a prefabricated base member, and undertaking an additive manufacturing process to construct features upon the prefabricated base member to form a component of a desired form comprising the prefabricated base and the constructed features.
2. A method according to Claim 1, wherein the base member includes a face upon which the features are formed, and the said surface is of non-planar form.
3. A method according to Claim 2, wherein a plurality of recesses are formed in the face and/or a plurality of projections are formed thereon, cooperating with the material delivered by way of the additive manufacturing process.
4. A method according to Claim 2, wherein the recesses and/or projections take the form of a series of ribs or grooves.
5. A method according to any of the preceding claims, wherein the prefabricated base member is supported upon a support device which is formed with a recess within which the prefabricated base is located.
6. A method according to Claim 5, wherein the upper face of the prefabricated base is substantially coplanar with the surface of the support device.
7. A method according to Claim 5 or Claim 6, wherein the location of the prefabricated base within the recess provided in the support device secures the prefabricated base against movement relative to the support device.9. A method according to any of Claims 5 to 8, wherein the prefabricated base is secured to the support device against movement relative thereto.10. A method according to any of Claims 5 to 9, wherein the support device is arranged to carry the prefabricated bases of several components, allowing several components to be fabricated using a single additive layer manufacturing process.11. A method according to any of the preceding claims, wherein a powder bed additive layer manufacturing process is used in the formation of the features.12. A method according to any of the preceding claims, wherein the prefabricated base is formed using a CNC machining process.13. A method according to any of the preceding claims, wherein the prefabricated base and the constructed features are of the same material.14. A method according to Claim 13, wherein the material is Inconel.15. A method according to any of Claims 1 to 12, wherein the prefabricated base and constructed features are of different materials.16. A manufacturing method comprising providing a prefabricated base member including a plurality of regions intended, in use, to form parts of a plurality of end products, and undertaking an additive manufacturing process to construct features upon each of the plurality of regions, and undertaking a finishing process to separate the regions from one another to form a plurality of components desired forms, each comprising a region of the prefabricated base and the constructed features formed thereon.17. A method according to Claim 16, wherein the base member is of relatively large dimensions, substantially covering a support table of an additive manufacturing device.18. A method according to Claim 16 or Claim 17, wherein the base member is machined, prior to undertaking the additive manufacturing process or after completion of the additive manufacturing process to form the regions thereof to a desired shape.19. A method according to any of Claims 16 to 18, wherein the face of the base member upon which the features are constructed, in use, is of non-planar form.20. A component comprising a prefabricated base member upon which features are constructed using an additive manufacturing process.21. A component according to Claim 20 and fabricated using a method as claimed in any of Claims 1 to 19.