Curved plate production by additive layer manufacture

Abstract

A method of producing a curved plate by additive layer manufacture is provided. The method includes building up the plate layer-by-layer such that a first layer forms a bottom edge of the plate and the plate is additively extended upwards therefrom by subsequent layers such that a last layer forms an opposing top edge of the plate. In this way, spaced, first and second lateral edges of the plate each grow layer-by-layer to extend between respective ends of the bottom and top edges. The plate thus built up arches over from the bottom edge to adopt a curved shape on cross-sections through the plate normal to the bottom edge.

Claims

1. A method of producing a curved plate by additive layer manufacture, the method including: building up the plate layer-by-layer such that a first layer forms a bottom edge of the plate and the plate is additively extended upwards therefrom by subsequent layers such that a last layer forms an opposing top edge of the plate, wherein spaced, first and second lateral edges of the plate each grow layer-by-layer to extend between respective ends of the bottom and top edges, and the plate thus built up arches over from the bottom edge to adopt a curved shape on cross-sections through the plate normal to the bottom edge; simultaneously building up layer-by-layer with the plate first and second sacrificial plate additions along respectively the first and second lateral edges, each sacrificial plate addition continuing the geometry of the plate beyond its lateral edge such that the additions also arch over from the bottom edge to adopt a curved shape on cross-sections through the additions normal to the bottom edge; and removing the sacrificial plate additions.

2. A method of producing a curved plate according to claim 1, wherein the sacrificial plate additions are thinned where they join to the plate along the first and second lateral edges.

3. A method of producing a curved plate according to claim 1, wherein the length of each sacrificial plate addition in the direction of the bottom edge is at least 5% of the length of the bottom edge.

4. A method of producing a curved plate according to claim 1, wherein the length of each sacrificial plate addition in the direction of the bottom edge is at most 30% of the length of the bottom edge.

5. A method of producing a curved plate according to claim 1, wherein the spacing between the first and second lateral edges and/or the spacing between the bottom and top edges is at least ten times greater than the thickness of the plate.

6. A method of producing a curved plate according to claim 1, wherein one or each of the sacrificial plate additions is anchored during plate build up by further additive layer material to a respective support structure.

7. A method of producing a curved plate according to claim 1, wherein the plate thus built up also has a curved shape on cross-sections normal to the direction of additive layer growth.

Description

DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present disclosure will now be described by way of example with reference to the accompanying drawings in which:

(2) FIG. 1 shows a result of finite element modelling of a plate produced by additive layer manufacturing (ALM);

(3) FIG. 2 shows a cross-sectional view at mid-height through the plate of FIG. 1 on a plane normal to direction z;

(4) FIG. 3 shows schematically a plate as built up from a base by ALM;

(5) FIG. 4 shows a result of finite element modelling of the plate of FIG. 4; and

(6) FIG. 5 shows a cross-sectional view at mid-height through a variant of the plate of FIG. 3 and FIG. 4 on a plane normal to direction z.

DETAILED DESCRIPTION

(7) FIG. 3 shows schematically a plate 30 built up from a base 31 by ALM. The plate 30 has a bottom edge 32 formed by the first ALM layer, and is additively extended upwards therefrom by subsequent layers to a top edge 33 formed by the last ALM layer. The plate has a curved shape on cross-sections through the plate normal to the bottom edge and consequently arches over the bottom edge. First and second lateral edges 34 of the plate extend between the bottom and top edges and join via thinned regions to respective sacrificial additions 35 which are built up by ALM simultaneously with the plate and continue the arched geometry of the plate beyond its lateral edges. Typically, the spacings between the first and second lateral edges and between the bottom and top edges are at least ten times greater than the thickness of the plate.

(8) The sacrificial material in the additions 35 behaves as an extension of the plate geometry so that distortions and plastic deformation which would otherwise occur along the lateral edges 34 are displaced to the additions, which are then removed after the ALM process, e.g. by machining.

(9) For example, FIG. 4 shows a result of finite element modelling of the plate 30, the direction and locations of the principal distortions being indicated by arrows. Relative to the modelling result of FIG. 1, the displacement of the edge distortions is evident. Such modelling can also be used to show that plastic strains are similarly displaced.

(10) The length of each sacrificial addition 35 in the direction of the bottom edge 32 can be in the range of from 5% to 30% of the length of the bottom edge. The lower limit is generally enough to ensure that most distortions are displaced to the addition, and the upper limit can avoid excessive material wastage.

(11) An advantage of this ALM method is that it is possible to avoid making contact onto critical surfaces of the plate 30 with stiffening supports.

(12) Moreover, relative to conventional approaches which attempt to combat distortions and plastic deformation by use of such stiffening supports, the ALM method can advantageously use lower volumes of sacrificial material and can better isolate of plastic deformations away from potentially sensitive locations (e.g. along the lateral edges 34). However, this does not exclude the adoption of a combined approach. Thus FIG. 5 shows a cross-sectional view at mid-height through a variant of the plate 30 on a plane normal to direction z. To supplement the sacrificial additions 35, members 36 produced by ALM extend therefrom and locate against support structures 37, which also make supporting contact with the plate 30 adjacent the lateral edges 34.

(13) The ALM method can advantageously be applied to the production of any ALM component with such an arched geometry.

(14) While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.