Abstract
A powder bed additive layer manufacturing apparatus for manufacturing a component, the apparatus including a base plate including a set of axes X, Y, Z and a first re-coater blade. The base plate includes a build surface for receiving powder, and the build surface includes a non-planar surface profile for complementing the shape of a component non-planar surface. The first re-coater blade has a blade profile that corresponds with a non-planar surface profile of the build surface. The first re-coater blade is configurable such that it can traverse across the build surface, for providing a layer of powder having a consistent depth across the non-planar build surface during the manufacturing process.
Claims
1. A powder bed additive layer manufacturing apparatus for manufacturing a component, the apparatus comprising: a base plate comprising a set of axes X, Y, Z; a first re-coater blade; wherein the base plate comprises a build surface for receiving powder, and the build surface comprises a non-planar surface profile for complementing the shape of a component non-planar surface; and the first re-coater blade has a blade profile that corresponds with the non-planar surface profile of the build surface; and the first re-coater blade is configured such that it can traverse across the build surface, for providing a layer of powder having a consistent depth across the non-planar build surface during a manufacturing process.
2. An apparatus according to claim 1, wherein the build surface comprises protrusions in the direction of the Z axis that are integral to the base plate, for complementing the shape of a component non-planar surface.
3. An apparatus according to claim 1, wherein the base plate is formed of a rigid material.
4. An apparatus according to claim 1, wherein the build surface has a non-planar, two-dimensional profiled first cross-section, coincident with the X axis; and the blade profile of the first re-coater blade corresponds with the profiled first cross-section and is configured to linearly traverse across the build surface along the Y axis.
5. An apparatus according to claim 4, wherein the build surface has consistent cross-sections along the Y axis.
6. An apparatus according to claim 4, further comprising: a second re-coater blade with a second blade profile; wherein the build surface has a non-planar, two-dimensional profiled second cross-section, coincident with the Y axis; and the build surface is defined by the intersection of projecting the profiled first cross-section along the Y axis and projecting the profiled second cross-section along the X axis; and the blade profile of the second re-coater blade corresponds with the profiled second cross-section; wherein the second re-coater blade is configured to linearly traverse across the build surface along the X axis, for providing a layer of powder having a consistent depth across the base non-planar build surface in combination with the first re-coater blade.
7. An apparatus according to claim 1 for manufacturing a part for a component of a gas turbine engine, wherein the powder is a metallic powder.
8. A method for providing a component having a non-planar surface using a powder bed ALM process comprising: providing a powder bed ALM apparatus according to claim 1, the method comprising: sequentially, depositing powder in layers parallel to the non-planar build surface; traversing the first re-coater blade along the axis whereby to provide a layer of powder having a consistent depth across the base plate non-planar surface, and selectively fusing portions of the layer to form the component shape.
9. A method according to claim 8, further comprising: providing a third re-coater blade with a different blade profile to the first re-coater blade profile; and after the step of selectively fusing a layer of the component, the first re-coater blade is substituted with the third re-coater blade.
10. A method according to claim 8, wherein: the powder bed ALM apparatus comprising a second re-coater blade with a second blade profile; wherein the build surface has a non-planar, two-dimensional profiled second cross-section, coincident with the Y axis; and the build surface is defined by the intersection of projecting the profiled first cross-section along the Y axis and projecting the profiled second cross-section along the X axis; and the blade profile of the second re-coater blade corresponds with the profiled second cross-section; wherein the second re-coater blade is configured to linearly traverse across the build surface along the X axis, for providing a layer of powder having a consistent depth across the base non-planar build surface in combination with the first re-coater blade; the method further comprising: traversing a second re-coater blade along the X axis across the surface of the powder.
11. A method according to claim 10, further comprising: providing a fourth re-coater blade with a different blade profile to the second re-coater blade profile; and after the step of selectively fusing a layer of the component, the second re-coater blade is substituted with the fourth re-coater blade.
Description
[0043] Embodiments will now be described by way of example only, with reference to the Figures, in which:
[0044] FIG. 1 is a powder bed ALM apparatus;
[0045] FIG. 2a is a side view of a part to be manufactured by ALM;
[0046] FIG. 2b shows the part of FIG. 2a in a part-built state without a support structure;
[0047] FIG. 2c shows the part of FIG. 2b in a part-built state with a support structure;
[0048] FIG. 2d shows the completed part of FIGS. 2a-2c with support structure attached in a powder bed;
[0049] FIG. 3a shows a curved base plate and re-coater blade;
[0050] FIG. 3b shows a side view of the base plate of FIG. 3a with the re-coater blade part way through traversing across the surface of the powder;
[0051] FIG. 3c shows an end-on view of the curved base plate of FIG. 3a with the first layer solidified;
[0052] FIG. 3d shows an end-on view of a part after made using the base plate and re-coater blade of FIGS. 3a to 3c, after multiple layers have been solidified;
[0053] FIGS. 4a-d shows a selection of shaped base plates;
[0054] FIG. 5a shows a baseplate with a double curvature;
[0055] FIG. 5b shows a first re-coater blade traversing across the baseplate of FIG. 5a;
[0056] FIG. 5c shows a second re-coater blade traversing across the baseplate of FIG. 5a;
[0057] FIG. 5d shows a top down view of the base plate of FIG. 5a;
[0058] FIG. 6a is a side view showing a method of constructing layers of a part around a step in the baseplate;
[0059] FIG. 6b is a side view showing the method of FIG. 6a with further layers added above the step; and
[0060] FIG. 7a and FIG. 7b show an alternative method of constructing layers around a step in the baseplate.
[0061] Referring to FIG. 3a there is provided a curved base plate 30. The base plate 30 has a set of axes X, Y, Z. The top surface of the base plate 30 is the build surface 34. The curve of the build surface 34 is defined by the build surface profile 32. The re-coater blade 36 can traverse along rails 38 in the Y direction.
[0062] The re-coater blade 36 has a blade profile that corresponds with the build surface profile 32. As can be seen in FIG. 3a, the re-coater blade 36 has the same profile as the build surface profile 32, such that when the re-coater blade 36 traverses along the Y axis it will always be at the same distance away from the build surface 34 for creating an even layer of powder in use.
[0063] The build surface profile 32 is an example of a two-dimensional cross-sectional profile aligned with the X axis. The curve in the build surface 34 is an example of a non-planar build surface.
[0064] FIG. 3b shows a side view of base plate of FIG. 3a i.e. looking along the X direction. FIG. 3b shows the re-coater blade part way through its passage across a layer of powder on the build surface. FIG. 3b shows the base plate 30, the re-coater blade 36, an un-smoothed layer of powder 40 as deposited on the base plate and a smoothed layer of powder 41 created by the action of traversing the re-coater blade 36 over the layer of powder 40.
[0065] The re-coater blade 36 traverses linearly along the Y direction, smoothing the powder as it travels. It can be seen from FIG. 3b how as the re-coater blade 36 traverses across the un-smoothed powder 40, it creates a smoothed layer of powder 41 of even depth across the base plate 30. The layer of powder 41 follows the curvature of the build surface 32.
[0066] FIG. 3c shows an end on view of the base plate of FIG. 3a i.e. looking along the Y direction. The figure shows the features of FIG. 3a as well as a solidified first layer 37 of the part to be manufactured and excess powder 38.
[0067] The first layer 37 of the part is solidified into the smoothed layer of powder 38 of FIG. 3b. The first layer 37 of the part also follows the curvature of the build surface 32 of the base plate 30. In FIG. 3c the re-coater blade 36 has been moved into position for the next, second layer of powder. This can be achieved by lowering the base plate 30 or raising the re-coater blade 36. The re-coater blade 36 has been moved by a distance equal to the depth of a first layer 37 of the part to be manufactured.
[0068] It can most clearly be seen in FIG. 3c how the shape of the blade of the re-coater blade 36 matches, or corresponds, with the shape of the build surface 32 of the base plate 30. This allows the re-coater blade 36 to create layers of powder of even depth across the build surface 32.
[0069] The parts of the layer of powder that haven't been solidified remain as excess powder 38 around the first layer 37.
[0070] FIG. 3d shows the same view as FIG. 3c but after multiple layers of powder have been deposited and solidified and the part 42 has been completed.
[0071] The base plate 30 in FIGS. 3a to 3d is prismatic. The shape fits the description of a prism whereby the two ends have the same shape and size and are parallel to each other (where one of the ends is shown, end on, clearly in FIG. 3c), and all other sides are parallelograms. The sides are parallelograms that connect all of the edges of the two ends to each other. The build surface 34 in FIG. 3 is a parallelogram that is curved so that it connects the top edge of each of the ends. The bottom surface of the base plate 30, i.e. the obverse of the build surface 34, is flat and all connected sides are at 90 degrees to the bottom surface.
[0072] A method of manufacturing a part can be explained using FIGS. 3a to 3d. Powder is deposited on the build surface 32 of the base plate 30 forming an un-smoothed layer of powder 40. A re-coater blade 36 is then traversed across the un-smoothed powder layer 40 creating a smoothed layer 41 of even depth across the base plate 30. These two steps can be seen in FIG. 3b whereby the re-coater blade 36 is part way across smoothing the un-smoothed layer of powder 40. Once the even layer of smoothed powder 41 is achieved, the parts of the powder 41 that correspond to the part are solidified using an energy source. This creates the first layer of the part 37. This can be seen in FIG. 3c, after the re-coater blade 36 has been raised (or the base plate 30 lowered) to accommodate the next layer of powder. It can be seen from FIG. 3c that excess powder 38 remains in the areas not solidified. The process is repeated for the next layer, and so on, until the part 42 is built up, as shown in FIG. 3d. Like FIG. 3c, FIG. 3d shows how the excess powder 43 remains around the part 42.
[0073] The part manufactured from the method described will have had its layers built up in curved layers rather than planar layers as in the prior art. Under scrutiny the curved layers will give the part different properties that will distinguish it from a part manufactured in planar layers. For example (but not limited to) grain structure under a microscope and mechanical properties in different directions.
[0074] Referring to FIGS. 4a to 4d, further examples of the shapes of the base plate are illustrated. All of the shapes, similar to that shown in FIG. 3, have two ends that have the same shape and are parallel to each other, with parallelograms connecting the two ends. Where the edges of the ends of the base plate are curved, the parallelograms that connect the respective curved edges of the two ends will also be curved. As can be seen in FIG. 4a, the set of axes X, Y and Z are also illustrated, and similar to FIG. 3 the direction X represents the direction over which the build surface is profiled and the direction Y represents the direction that the re-coater blade traverses in over the build surface, and also the direction that the build surface is even or linear.
[0075] FIGS. 4a to 4d show different profiles of the base plate and build surface. For example FIG. 4a shows a stepped profile including step 44 to create a central raised portion with a curved section 46. However in other examples there could be a plurality of steps. The plurality of steps can create various raised portions or portions at different heights. FIG. 4b shows how the shape can comprise two steps 44. FIG. 4c shows another combination of a shallow curvature 43 and a step 44. FIG. 4d shows protrusions 48 from the baseplate. These protrusions 48 can be a square shaped protrusion extending out of the baseplate or a curved shaped protrusion, both of which are shown on FIG. 4d. The protrusions 48 can be any shape, for example a combination of straight sections and curved sections. In FIG. 4d they extend out of the base plate in a direction normal to the plane of the build surface i.e. in the Z direction. The examples shown in FIG. 4d include vertical (i.e. normal to the plane of the build surface of the base plate) parts of the protrusion but no undercuts. An undercut would extend away from the base plate at an acute angle to the plane of the build surface. An undercut of a protrusion would be formed by the protrusion extending over the base plate such that material of the protrusion extends over the material of the base plate with a gap in between.
[0076] In other embodiments the base plate can be any shape. The axes X, Y and Z are orthogonal axes in FIGS. 3 and 4 but they can be at other angles to each other if the base plate does not have square corners.
[0077] Referring to FIGS. 5a to 5d there is provided a base plate 48 with a curvature 52 of the build surface 51 defined by the interaction of two two-dimensional profiles 50 and 53. FIG. 5a shows two profiles, profile one 50 and profile two 53. Profile one 50 and profile two 53 are two dimensional profiles. Profile one 50 and profile two 53 are profiles of the base plate 48 in FIG. 5a but they can also just be profiles of the build surface 51 i.e. a profile that is a line rather than the closed profiles shown in FIG. 5a. A set of axes X, Y and Z are shown.
[0078] Profile one 50 is a two-dimensional profile coincident with the X axis and profile two 53 is a two-dimensional profile coincident with the Y axis. The axes in FIG. 5a are orthogonal axes, however other arrangements of axes are possible. The shape of the build surface 51 includes a curvature 52 in more than one direction. For example the build surface 51 is defined by the interaction of extending profile one 50 in direction Y and extending profile two 53 in direction X and constructing the shape of the base plate from the volume intersected by profile one 50 and profile two 53 i.e. the volume swept by both profiles. In alternative embodiments profile one and profile two are just profiles of the build surface and the curvature of the build surface is defined by the intersection of projecting profile one along the Y axis and profile two along the X axis.
[0079] FIG. 5b shows the base plate 48 of FIG. 5a with a first re-coater blade 54. FIG. 5c shows the base plate 48 of FIG. 5a with a second re-coater blade 56. The shape of the build surface 51 defined by profile one 50 and profile two 53 are such that a first re-coater blade 54 can travel over the surface in direction Y whereby the shape of the profile of the first re-coater blade 54 corresponds to the first profile 50. The second re-coater blade 56 can travel over the surface in a linear direction coincident with direction X. FIG. 5b shows the first re-coater blade 54 part way through traversing across the build surface 51 and FIG. 5c shows the second re-coater blade 56 part way through traversing across the build surface 51. The build surface 51 can be defined by sweeping the first re-coater blade 54 across the base plate 48 in the Y direction and traversing the second re-coater blade 56 across the base plate 48 in the X direction and creating the build surface 51 from the volume underneath the swept volumes of the first re-coater blade 54 and second re-coater blade 56.
[0080] The first re-coater blade 54 and second re-coater blade 56 are arranged such that once they have traversed over the build surface 51 the powder will be an even vertical depth (i.e. in the Z direction) over the build surface 51.
[0081] Referring to FIG. 5d, a plan view of the base plate is shown with a double curvature. In this embodiment, the directions X and Y are orthogonal. In other embodiments, other angles between X and Y may exist.
[0082] Referring to FIGS. 6a and 6b there is provided a shaped base plate 59 and re-coater blade 61 whereby the shape of the re-coater blade 61 corresponds with the shape of the base plate 59. The base plate 59 includes a step with a vertical side. FIGS. 6a and 6b show a method of manufacturing a part in layers 60 around the step. First, as shown in FIG. 6a, the material below the step is built up using a re-coater blade 61 that corresponds in profile to the base plate 59. After the material is built up to the level of the top of the step, the re-coater blade 61 is changed so that the profile of the replaced re-coater blade 58 corresponds to both the top of the step and the material built up below the step. As can be seen in FIG. 6b, the replaced re-coater blade 58 now has a flat profile. Further layers 62 are then built up that span both the top of the step and the layers 60 below the step.
[0083] FIGS. 6a and 6b show the layers 60 and 62 as a plurality of distinct layers. This is for diagrammatical purposes, in the completed part the layers may not be visibly distinct from each other (although apparent under scrutiny).
[0084] An alternative embodiment of the method for building a part around a step is shown in FIG. 7. FIG. 7a shows how material is built up using a base plate 59 and a blade profile 61 that match. The layers 60′ are built up above and below the step simultaneously but include a disjoint across the step. Once the layers 60′ below the step has been built up to the height of the top of the step then further layers 64 are built up between disjoint between the layers 60′ above and below the step. The further layers 64 are for joining the layers 60′ below the step and above the step.
[0085] 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.
