Patent Application
20220134674
Following a build operation to generate one or more printed parts in a three-dimensional (3D) printer, the printed parts may be subjected to post-processing steps such as chemical polishing. In order to carry out such post-processing steps, an operator may remove printed parts from a build chamber and transfer them to a post-processing chamber, such as a chemical polishing chamber.
After the completion of the build operation in a 3D printer or other additive manufacturing system, printed parts may undergo post-processing steps in order to finish the parts to a particular specification. For example, in powder-based 3D printing processes, post-processing may include sandblasting of the printed parts to remove remaining powder on the part. Post-processing may also, for example, include chemical polishing of the printed parts to remove surface layering and achieve a high level of surface smoothness. Such post-processing steps may be conducted by an operator removing the printed parts from the build chamber of the 3D printer, and transferring them to a post-processing chamber. The operator may load individual printed parts onto a support structure which is housed within the post-processing chamber during the post-processing step.
The present disclosure describes how a supporting frame may be determined, that is suitable for supporting the part(s) during post-processing, and how modified model data is generated representing both the object and the frame. The provision of the supporting frame may facilitate the handling of the printed object by an operator, for example when transferring the printed object, for example from the build unit, for example to a post-processing apparatus. In particular, where the build operation generates a plurality of individual parts, a printed frame that supports all of these parts may enable an operator to easily transfer all parts from the build unit for post-processing by handling the frame, rather than handling each part individually, and may also allow for ease of subsequent removal of the parts from the post-processing apparatus. In this case, the frame may also serve to maintain a separation between individual parts during post-processing, thereby preventing individual parts from coming into contact and, for example, fusing together during chemical polishing.
The frame may be arranged to envelop the part(s), which may protect the parts when being handled by an operator, for example during transfer to a post-processing chamber, by enabling the frame to be simply placed in the chamber, without the need to load individual parts onto a separate support structure. In this example, the frame may be arranged such that a portion of the frame extends beyond the object on all sides, such that the object will be supported by a portion of the frame when placed on a surface in any orientation.
The present disclosure describes how, during a pre-print procedure, object model data defining an object to be printed may be used to determine such a supporting frame and generate modified model data representing both the object and the supporting frame.
In an example of the disclosure, the process of producing a 3D-printed object to a particular specification may include: (i) part and build preparation; (ii) 3D printing; and (iii) post-processing. During the part and build preparation, a digital model of each object to be printed, comprising object model data representing the object, may be generated or received by a pre-print application. A supporting frame may then be determined around the object(s) to be printed, wherein the frame may be determined in accordance with a number of criteria, as described below. Parameters specifying the size and location of the frame may be determined manually by a user, or automatically in the pre-print application. In some examples, parameters may be specified by a combination of manual and automatic processes, for example by the pre-print application generating a proposed frame structure which may then be accepted, rejected or modified by the user. Automatic determination of the frame structure may utilise machine learning techniques. Digital models of objects to be printed, and associated supporting frame(s), may be packed into the available build volume, either manually or using an automated packing algorithm, and such packing may be selected to minimise build height in order to maximise the efficiency of the build process. Modified model data may then be generated representing both the object to be printed and the supporting frame. The pre-print application may generate slices of the modified model data which may be sent to the printer for print data generation. Alternatively, the slices of the modified model may be extracted within the printer itself to generate printer control data. During 3D printing, the object and supporting frame may be generated by the 3D printer.
After printing is completed the printed parts may undergo cooling, and may then undergo post-processing. As described above, post-processing may include removal of excess powder in the case of a powder-based 3D printing process, and may include chemical polishing in a chemical polishing chamber. The printed parts may then be removed from the chamber and detached from the supporting frame.
The base portion 301 may be designed in such a way that it acts as a robust link between the frame base portion 303 and the connector portion 302 of the branch 300. The base 301 may have a broad support area, as shown in this example by the base portion 301 having a cylindrical shape having a circular cross-section of diameter D1, resulting in contact area A1 with the frame base portion 303 which is sufficient to secure the branch 300 to the frame during handling and post-processing. In this example, the base portion 301 is fully defined by parameters representing its length L1 and diameter D1. Other configurations and cross-sectional shapes may be used for the base portion 301.
In some examples, the connector portion 302 may be determined in such a way that it is robust against post-processing methods, but still allows easy removal of the object 304 afterwards with minimal aesthetic impact on the surface of the object. In the example of
In some examples, the parameters defining the shape of the base portion 301 and connector portion 302 of the branch 300 may be set via dynamic computation of the strength of the branch as a function of these parameters, in order to ensure sufficient strength to support the mass of the object, which may be specified in the object model, or determined on the basis of object dimensions derived from the object model. This may entail determining parameters of the base portion and connector portion that would provide sufficient support for the object 304 during the post-processing stages. The mass of the branch itself may also be dynamically computed as a function of the parameters defining the shape of the branch, and a minimisation of this function may be performed in order to determine parameters of the branch which provide sufficient strength to support the object, with minimal material used to produce the branch. In some examples, the parameters of each branch may be determined in such a way as to minimize the number of branches 300 required to support the object 304. Minimising the number of branches may increase the exposure of the object to processes such as chemical polishing during post-processing, which may thereby increase the effectiveness of such processes, and may also facilitate the detachment of the frame from the object by minimising the number of attachment points, which may reduce operator time required for such detachment.
In some examples, one or more of the branches may comprise a single base portion having multiple connector portions extending from it. Each of these multiple connector portions may have the properties of the single connector portion described above, and may have independent parameters determined for each respective connector portion to support the object or respective objects.
In some examples, the attachment locations and number of the branches may be determined based on, for example, a determination of the mass and/or center of mass of the object. For example, a determination of the mass of the object may be made based on the dimensions of the object specified in the object model data, and the number of branches may be determined in proportion with the mass of the object, in order to provide sufficient support for the object. In an example, the center of mass of the object may be determined from the object model data, and the attachment location(s) of the branch(es) on the object may be determined in such a way as to increase the stability of the support provided by the branches. For example, the locations of the branches may be determined relative to the center of mass so as to reduce torsional load on the branches at the attachment points when the object is supported by the frame, and for example, the attachment locations may be determined such that the center of mass lies between the attachment points.
In some examples, the object model data comprises multiple parts to be generated, and the determination of the frame is made in accordance with the requirement to envelop and support all of the parts simultaneously.
At 403, modified model data is generated, representing both the object and the frame. This modified model data may be used to generate slices in a pre-print application which may then be transmitted to a 3D printer, or extracted within the printer itself.
At 506, properties of the branches are determined so that the object will be supported during post-processing steps. These properties may include the geometrical parameters of the branches, described above with reference to
When determining the structure of the frame, a number of constraints may be satisfied in order to increase the effectiveness of the frame, and these may include, but are not limited to, any or all of:
(i) reducing the number of branches and/or the surface area of the frame base portion, while retaining sufficient strength to support the object, in order to facilitate exposure of the object to post-processing steps such as sandblasting and/or chemical polishing, as well as reducing the additional material used to produce the frame;
(ii) providing the frame with sufficient strength and with geometry suitable to at least partially surround the object or objects to enable printed objects to be handled and stacked in a post-processing chamber without printed objects touching one another, whether printed objects are supported by separate respective frames, or multiple objects are supported by a single frame;
(iii) providing sufficient branches to support the object in a robust way, while minimising the number of branches to facilitate detachment of the object from the frame;
(iv) determining junctions between branches and the object in areas of the object determined or specified to have low aesthetic importance.
In some examples, suitable contact areas, reflecting possible locations on the object where the branches may be connected, may be identified either manually, automatically or a combination of both. For example, suitable contact areas may be identified in accordance with regions of higher or lower curvature, or regions where concavities or convexities exist in the object surface.
It should be understood that
In some examples, the determination of the properties and locations of the branches and frame base portion may take place in a different order from that shown in
It is to be understood that the determination of the frame, and the number and location of the branches, may be made in accordance with any of the above described methods. This determination may be made automatically, manually, or a combination of the two, for example by providing an automated determination and using a user input to modify the automated determination.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/040994 | 7/9/2019 | WO | 00 |
