TOOLS COMPRISING REPEATING STRUCTURES FORMED USING ADDITIVE MANUFACTURING PROCESSES

In some examples, a tool for manufacturing parts includes a body formed using an additive manufacturing process, where the body includes a plurality of repeating structures, and where the plurality of repeating structures include a first subset of repeating structures each having a first physical property as specified by a digital representation of the tool used in the additive manufacturing process, and a second subset of repeating structures each having a different second physical property as specified by the digital representation of the tool used in the additive manufacturing process.

BACKGROUND

Molded fiber manufacturing uses molded fiber (also referred to as a molded pulp) to manufacture products. The molded fiber can include cellulose fibers, which can be made from recycled paper, cardboard, and so forth. Examples of products that can be manufactured using molded fiber manufacturing include trays, plates, containers, or other products.

A molded fiber manufacturing process uses a fibrous slurry including cellulose fibers suspended in a liquid, such as water. Mold tools are immersed in a tank filled with the fibrous slurry. The mold tools include a form and a screen. The form supports the screen, which defines a target shape of a product to be manufactured by the molded fiber manufacturing process.

A suction device can draw the fibrous slurry onto a surface of the screen, which has small pores. The liquid in the fibrous slurry is drawn through the pores of the screen, and the liquid exits through pores in the form to a plenum. The remaining portion of the fibrous slurry is a part that takes the shape of the form. In some molded fiber manufacturing processes, a transfer tool (another mold tool) can then be used to transfer the part away from the screen, and the transfer tool can move the part to another location for drying, such as in an oven or another location where heat can be applied to the part, or the part can be air dried.

The form, screen, and transfer tool are examples of mold tools that are used as part of a molded fiber manufacturing process. In other examples, molded fiber manufacturing processes can employ different techniques and mold tools.

DETAILED DESCRIPTION

Pores (openings) are examples of repeating structures that can be formed in mold tools used in molded fiber manufacturing processes. A pore is an opening in a tool, such as an opening to allow a flow of a liquid through the opening. Other types of repeating structures can also be formed in the mold tools, including pillars, dimples, protrusions, and so forth. A “pillar” can refer to any support structure that supports a tool against another item, such as another tool. A “dimple” can refer to an indentation on a surface of a tool, and a “protrusion” can refer to a raised portion on a surface.

As used here, “repeating structures” can refer to structures on a tool (e.g., a mold tool) to be used during a manufacture (e.g., as part of a molded fiber manufacturing process) of a part. The repeating structures are repeatedly placed at multiple locations on a tool. As an example, a pore of a given size or shape can be repeated across multiple locations on a tool. The repeating structures can be arranged in a grid or in another pattern.

In some examples, mold tools are hand-made. For example, a screen can be made up of fine metal mesh hammered into place over form tools that are machined metal blocks with holes drilled through them. Pores in other mold tools can be formed by manually drilling the pores. Manually making mold tools can be labor intensive and costly.

In other examples, mold tools can be manufactured using subtractive manufacturing techniques, in which various features (including repeating structures) of the mold tools are formed by cutting away portions of a block of material. Manual subtractive manufacturing techniques may not reliably form small dimension repeating structures on mold tools, and may also be associated with relatively high manufacturing costs.

In accordance with some implementations, techniques or mechanisms are provided to build tools (such as mold tools used in molded fiber manufacturing processes) using additive manufacturing machines. As used here, a “tool” is a component that is used to build a physical part.

In some examples, techniques or mechanisms are provided to automate the design of tools to generate digital representations of the tools that are to be used by additive manufacturing machines in building the tools. In some examples, digital representations of the tools can be in the form of computer-aided design (CAD) files that can be provided to additive manufacturing machines to build the tools described in the CAD files. In other examples, other types of digital representations of tools can be used.

Additive manufacturing machines produce three-dimensional (3D) objects by accumulating layers of build material, including a layer-by-layer accumulation and solidification of the build material patterned from digital representations of physical 3D objects to be formed. A type of an additive manufacturing machine is referred to as a 3D printing system. Each layer of the build material is patterned into a corresponding part (or parts) of the 3D object, based on application of a liquid agent to selected portions of the layer, followed by a further processing (e.g., heating) of the layer after the liquid agent is applied.

Building tools using additive manufacturing processes allows for better control of properties of structures, including repeating structures, on the tools, as compared to traditional manufacturing techniques. Also, building tools using additive manufacturing processes can be associated with faster turnaround times and lower manufacturing costs as compared to traditional manufacturing techniques.

Automated techniques or mechanisms for designing tools to be built by additive manufacturing processes can consider a variety of information relating to a tool to be built when setting properties of repeating structures of the tool. For example, the properties of the repeating structures can include sizes and/or shapes of pores, dimensions of pillars that support screens or other tools, and so forth. The foregoing are examples of physical properties of repeating structures of tools.

In some examples, properties of repeating structures can be determined based on which regions of a tool are associated with higher liquid flow than other regions of the tool. Pores in a region associated with a potentially higher liquid flow can be designed to be smaller, or alternatively, can be arranged to have a lower density of pores. An example of a region of a tool with a potentially increased liquid flow is a region where inclined surfaces or other features tend to focus liquid flow to the region.

As another example, pillars may be used to support a screen on a form. A “form” is a tool that has a general shape of the screen and is used to support the screen during a molded fiber manufacturing process. In the molded fiber manufacturing process, an assembly of the screen placed on the form can be dipped into a fibrous slurry including cellulose fibers suspended in a liquid. A suction device pulls the fibers onto the screen, and the liquid of the fibrous slurry flows through the pores of the screen and pores in the form into a plenum. A part to be built using the molded fiber manufacturing process takes the general shape of the screen. A transfer tool can then be used to transfer the part on the screen away from the screen, and the transfer tool can move the part to another location for drying. The transfer tool may also include pores and/or other repeating structures.

In further examples, there may be certain regions of a screen where it may be desired to control lateral liquid flow between pillars that support the screen on a form. “Lateral liquid flow” can refer to flow that occurs in a direction between the screen and the form in a direction that is generally perpendicular to a direction of liquid flow into a pore of the screen. To reduce lateral liquid flow, the pillars may be made larger (e.g., larger diameter), or a denser arrangement of pillars may be provided on the screen. To increase lateral liquid flow, the pillars may be made smaller, or a sparser arrangement of pillars may be provided on the screen.

As a further example, where powdered build material is used by an additive manufacturing machine to build a tool, it may be difficult to clean residue powder (left over from the build process of the additive manufacturing machine) from the tool in certain regions of the tool. Pores in such regions may be made larger to make it easier to remove residue powder from the regions.

As yet another example, even though a digital representation of a tool may specify that repeating structures be formed of the same size, the physical repeating structures as formed by an additive manufacturing machine on the tool may vary in size. This may occur if the orientations of build surfaces vary across the tool. For example, forming a pore on a sharply inclined surface of the tool may result in the pore deviating from a target size. To account for this, automated techniques or mechanisms can adjust the digital representation of the tool to specify different sizes of pores for different areas of the tool, to allow the pores when actually built by the additive manufacturing machine to have the same target size. Pores of a “same target size” if the sizes of the pores are within a specified percentage of one another (e.g., within 1%, within 2%, within 5%, within 10%, etc.).

Control of properties of repeating structures of tools to be built by additive manufacturing processes can also consider other factors, in addition to or instead of the factors noted above.

FIG.1Ais a block diagram illustrating use of an additive manufacturing process102in building a tool104. The additive manufacturing process102is implemented using an additive manufacturing machine103.

A digital representation106(e.g., a CAD file) of the tool is provided as an input to the additive manufacturing process102, which builds the tool104on a layer-by-layer basis. In the additive manufacturing process102, a first layer of build material (e.g., powdered build material such as powdered polymer, powdered metal, etc.) is deposited onto a build bed of an additive manufacturing machine, and the layer of build material is then processed (a liquid agent applied, heat applied, etc.) according to a slice of the digital representation106, where the slice corresponds to the layer of build material. Once the layer of build material has been processed, a subsequent layer of build material is formed on the previously processed layer of build material, and the subsequent layer of build material is processed using another slice of the digital representation106. The foregoing is repeated until the tool104is built according to the digital representation106.

The tool104includes a body108. In some examples, the tool104ofFIG.1Ais a screen used in a molded fiber manufacturing process. In other examples, the tool104includes a form, a transfer tool, and so forth.

The body108of the tool104includes repeating structures in the form of pores. In the example ofFIG.1A, the pores are of various different sizes and shapes.

The pores in the body108include generally circular pores110-1and110-2. The pores110-2have a larger size (e.g., larger diameter) than the pores110-1. In some examples, the smaller pores110-1are located in corner regions112-1of the body108of the tool104, while the larger pores110-2are located in generally a central region112-2of the body108of the tool104.

In some examples, greater liquid flow may potentially be present in the corner regions112-1as compared to the central region112-2. If the tool104is used in a molded fiber manufacturing process, then the liquid flow can include a flow of a liquid (e.g., water) of a fibrous slurry that includes cellulose fibers supported in the liquid. The liquid of the fibrous slurry is allowed to pass through the various pores shown inFIG.1A.

The potentially greater liquid flow in the corner regions112-1may be due to the presence of other features (e.g., of another tool) adjacent the tool104during a molded fiber manufacturing process. The adjacent features may focus liquid flow towards the corner regions112-1, which results in a greater potential liquid flow rate in the corner regions112-1as compared to the central region112-2, unless countermeasures are employed. To counter the potentially greater liquid flow rate in the corner regions112-1, the pores110-1can be made to have a smaller size as compared to the pores110-2. The smaller size of the pores110-1effectively reduces liquid flow rate through the pores110-1to allow the effective liquid flow rate through the pores110-1and110-2to be approximately the same.

In other examples, other regions of a tool may have potentially greater liquid flow rates.

In examples according toFIG.1A, pores110-3have rectangular shapes, and pores110-4have diamond shapes. In other examples, the pores110-1and/or the pores110-2can have an elliptical shape. Pores of different shapes may be used for different reasons, such as to fit pores into a small area to avoid the pores overlapping, or to fit a larger quantity of pores in an edge region to allow for as much fluid flow as possible, or for any other reason.

In other examples, pores of different shapes are not used on the body108of the tool104. Rather, pores of just one shape, such as a circular shape, can be used. For example, the pores on the body108of the tool104can have a circular shape such as the pores110-1and110-2, and the rectangular pores112-3and diamond-shaped pores112-4are not used.

Note that the pores110-1,110-2,110-3, and110-4of different shapes can also have different sizes relative to one another.

More generally, a tool for manufacturing parts (such as the tool104ofFIG.1A) includes a body formed using an additive manufacturing process, where the body includes a plurality of repeating structures, and where the plurality of repeating structures include a first subset of repeating structures each having a first physical property as specified by a digital representation (e.g.,106inFIG.1A) of the tool used in the additive manufacturing process, and a second subset of repeating structures each having a different second physical property as specified by the digital representation of the tool used in the additive manufacturing process.

FIG.1Bis a perspective view of a portion of a screen150including pores of different sizes, according to some examples. The screen150includes a first screen surface152inclined with respect to a second screen surface154. For example, the first screen surface152may be parallel to or have a relatively small incline with respect to a build bed of the additive manufacturing machine103, and the second screen surface154may have a larger incline with respect to the build bed than the first screen surface152. A “build bed” can refer to a surface of a build platform of the additive manufacturing machine, or alternatively, to previously processed layer(s) of build material. In the example ofFIG.1B, the first screen surface152has pores156of a first size (e.g., first diameter), and the second screen surface154has pores158of a second size (e.g., second diameter) larger than the first size. In other examples, the pores156may have a smaller size than the pores158.

FIG.2is a cross-sectional view of a screen202mounted over a form204. The screen202has a shape to generally define a shape of a part to be formed by a molded fiber manufacturing process using the screen202and the form204.

The screen202includes a first collection of pores206-1of a first size, and a second collection of pores206-2of a second size that is greater than the first size. If the pores206-1and206-2are circular pores, then the first size is a first diameter of each pore206-1, and the second size is a second diameter of each pore206-2.

Each pore206-1or206-2extends through a thickness T1of a body208of the screen202. The pores206-1and206-2allow for a liquid (e.g., the liquid of a fibrous slurry) to flow through the pores, as indicated by arrows210. A layer of fibers of the fibrous slurry is left on an upper surface213of the screen202after the liquid is suctioned through the pores206-1,206-2of the screen202.

Pillars212-1and212-2are used to provide support for the screen202on the form204. The pillars212-1,212-2can be part of the screen202or part of the form204. In some examples, the pillars212-1,212-2define a separation in the form of a space214between the screen202and the form204.

In some examples, the pillars212-1can have a first size, and the pillars212-2can have a second size larger than the first size. In some examples, each pillar212-1,212-2is cylindrical in shape. The different sizes of the pillars212-1and212-2can include different diameters of the cylindrical pillars. In other examples, the pillars are of a shape different from a cylindrical shape. In further examples, different sizes of pillars can refer to different lengths of pillars. For example, the pillars212-1can have a first length while the pillars212-2can have a second length different from the first length.

In some examples, the size (or other physical property) of the pillars212-1may correspond to the size (or other physical property) of the pores206-1, and the size (or other physical property) of the pillars212-2may correspond to the size (or other physical property) of the pores206-2.

In further examples, the sizes (or other physical properties) of the pillars212-1,212-2can be based on another factor, such as lateral liquid flow. A liquid can flow laterally in gaps between successive pillars212-1,212-2. For example, a lateral liquid flow can be present through a gap216-1defined between smaller pillars212-1. The lateral liquid flow through the gap216-1is generally perpendicular to a direction of liquid flow through a pore206-2. As another example, a lateral liquid flow can be present in another gap216-2defined between larger pillars212-2. The gap216-2is smaller than the gap216-1.

In some cases, different regions of the space214can be associated with different lateral liquid flow rates due to geometries of the screen202and/or the form204, as well as geometries of other features that may be in the proximity of the screen202and the form204. For example, features may direct liquid to flow from a first number of locations (e.g., liquid flow channels) into the gap216-2, while liquid flowing into the other gap216-1is from a smaller number of locations (e.g., liquid flow channels). As a result, the liquid flow rate into the gap216-2can be larger than the liquid flow rate into the gap216-1, unless a countermeasure is employed.

To counter the differences in potential lateral liquid flow rates in the gaps216-1and216-2, the sizes (e.g., diameters) of the pillars212-1and212-2can be made to be different. The smaller sized pillars212-1can define larger gaps (e.g.,216-1) between successive pillars212-1, while the larger sized pillars212-2can define smaller gaps (e.g.,216-2) between successive pillars212-2.

Reducing the size of a gap between pillars effectively provides less space for liquid to flow, which can counter potentially larger lateral liquid flow rates in certain in the space214.

As further shown inFIG.2, the form204has a body220that also includes a first collection of pores222-1of a first size (e.g., first diameter), and a second collection of pores222-2of a second size (e.g., second diameter) larger than the first size.

Liquid flowing into the pores206-1,206-2and through the space214can flow through the respective pores222-1,222-2to exit a lower side224of the form204. Although not shown, a suction device can be provided below the lower side224of the form204to draw the liquid from a fibrous slurry through the pores206-1,206-2, the space214, and the pores222-1,222-2.

In addition to controlling liquid flow rates through pores of the screen202and the form204, adjusting pore sizes in the screen202and/or the form204can also control a thickness of a layer of fiber that is formed on the upper surface213of the screen202. Increasing pore sizes can allow for a larger liquid flow rate, and thus a greater quantity of the liquid of a fibrous slurry can be drawn through the screen202and form204per unit time. Drawing a greater quantity of the liquid of the fibrous slurry through the screen202and form204can allow a larger thickness of fiber to be formed on the upper surface213of the screen202.

FIG.3is a flow diagram of an automated process300of providing a digital representation of a tool, where the digital representation is to be used by an additive manufacturing machine to build the tool according to the digital representation. The process300can be performed by a computer system, which can include a computer or multiple computers.

The process300includes receiving (at302) information relating to the tool useable for manufacturing parts. The received information can include any or some combination of the following, as examples: liquid flow rate information for region(s) of the tool (e.g., information identifying a given region as a region of potentially high liquid flow rate, information specifying a liquid flow rate range through a given region, etc.), an orientation of a surface on which a repeating structure is to be formed (where the orientation can be measured relative to an additive manufacturing machine build bed surface, for example), information indicating that a given region of the tool is associated with an increased difficulty in cleaning residue build material powder (left over from an additive manufacturing process used to build the tool), information indicating that a given region of the tool is associated with a deviation in a physical property of a repeating structure when formed in the given region (e.g., a pore of the tool may be formed to be smaller or larger than a target size because the pore is in a highly inclined surface of the tool), information indicating a presence of an obstruction or other mass that may impact a liquid flow, and so forth.

Based on the received information, the process300determines (at304) physical properties of a plurality of repeating structures of the tool, where the determining includes specifying a first physical property for a first subset of the plurality of repeating structures, and specifying a different second physical property for a second subset of the plurality of repeating structures.

For example, if the received information indicates that a liquid flow rate through a given region of the tool is potentially larger than another region of the tool, then the process300can set pores in the given region to have smaller sizes to counter the potentially larger liquid flow rate through pores in the given region.

As a further example, the received information can specify an angle of a surface of the tool relative to a plane of a build bed in an additive manufacturing machine. The surface of the tool is the surface in or on which a pore or other repeating structure is to be formed. An orientation of the surface of the tool refers to the angle of this surface relative to the plane of the build bed (which can be horizontal or which can be inclined). The process300can compute a size of a repeating structure (e.g., a pore) based on the determined orientation of the surface.

As another example, if the received information indicates that a lateral liquid flow rate between pillars in a given region of the tool is potentially larger than another region of the tool, then the process300can set the pillars in the given region to have a larger size to reduce the size of gaps between successive pillars in the given region, to counter the potentially larger lateral liquid flow rate in the given region.

As a further example, if the received information indicates that a given region of the tool is associated with an increased difficulty in cleaning residue build material powder, then the process300can set pores in the given region of the tool to be larger to allow the residue build material powder to more readily pass through the pores when cleaning the tool after being built by an additive manufacturing process. More generally, the process300sets a physical property of a repeating structure based on a factor relating to cleaning residue powdered build material, where the factor can include ease of cleaning the residue powdered build material, an amount of residue powdered build material expected to be present, and so forth.

As yet another example, if the received information indicates that a given region of the tool is associated with a deviation in a physical property (from a target physical property) of a repeating structure when formed in the given region (e.g., a pore of the tool may be formed to be smaller or larger than a target size because the pore is in a highly inclined surface of the tool), then the process300can adjust the physical property to deviate from the target physical property in the digital representation to be created by the process300. For example, pores in a first region of the tool and a second region of the tool are supposed to have the same target size. However, the first region of the tool may have a highly inclined surface that may cause a pore formed in the first region to deviate from the target size when built by an additive manufacturing process even though a digital representation of the tool specifies that the pore is to have the target size. To counter this effect, the process300can set pores in the first region to have a different size (different from the target size), and can set pores in the second region to have the target size, such that when the tool is built by an additive manufacturing process, the pores in the first region and the pores in the second region as built by the additive manufacturing process will have approximately the same size (e.g., within 1% of one another, or within 2% of one another, or within 5% of one another, or within 10% of one another, etc.).

As yet a further example, if the received information indicates a presence of an obstruction or other mass in a given region that may impact a liquid flow, then the process300can adjust a physical property (e.g., a size) of repeating structures in the given region to account for the presence of the obstruction or other mass. For example, as shown inFIG.4A, a pillar402depending from a lower surface404of a screen400may partially obstruct a pore406in a given region408of the screen400. To account for this obstruction or other mass of the pore406(which may reduce a liquid flow rate through the pore406), the process300can increase a size of a pore406A so that an effective liquid flow rate area of the pore406A matches a target liquid flow rate area. For example, the process300can increase a diameter of the pore406A by an amount410relative to the pore406ofFIG.4A, to counter the liquid flow obstruction or other mass presented by the pillar402. More generally, a physical property of a pore or another repeating structure of a tool may be adjusted based on presence of a mass in a proximity of the repeating structure.

The process300generates (at306) the digital representation of the tool, the digital representation including information specifying the first physical property for the first subset of the plurality of repeating structures, and specifying the second physical property for the second subset of the plurality of repeating structures.

FIG.5shows an example of determining a size (e.g., a diameter D) of a pore302, which can extend through a screen, a form, or any other type of tool. The pore302is depicted as having a cylindrical shape and is defined within a body of a tool.

In some examples, the diameter D of the pore302is based on an orientation of the pore302with respect to a horizontal axis and a vertical axis. The pore302is formed in a surface304that is inclined with respect to each of the horizontal axis and the vertical axis.

For the pore302that is inclined with respect to both the vertical axis and the horizontal axis, a diameter D(θ) of the pore302is a modulated value derived from Dhorizontaland another parameter Dadditional, such as according to the equation below:

In the above equation, θ represents the angle of the surface304in which the pore302is formed, such as relative to a horizontal surface. Thus, θ can range between 0 (if the pore302is formed in the horizontal surface) and π/2 (if the pore302is formed in the vertical surface).

Note that Dvertical=Dhorizontal+Dadditional, since sin(π/2) is equal to 1. Thus, if Dverticaland Dhorizontalare preset values, then Dadditionalcan be derived from the relationship above.

In other examples, other equations for determining the diameter D of the pore302can be used.

In some examples, it can be assumed that the horizontal axis is in a plane of a build bed in an additive manufacturing machine. In examples where the build bed has a surface that is not in a horizontal plane, then the “horizontal” axis can refer to an inclined axis.

FIG.6is a block diagram of a non-transitory machine-readable or computer-readable storage medium600storing machine-readable instructions that upon execution cause a system to perform various tasks. The system can include a computer or multiple computers.

The machine-readable instructions include tool information reception instructions602to receive information relating to a tool useable for manufacturing parts.

The machine-readable instructions include repeating structures physical properties determination instructions604to, based on the information that is indicative of an interaction of a material with the tool (e.g., liquid flow rate in a region of the tool, residue powdered build material removal from the tool, etc.), determine physical properties of a plurality of repeating structures of the tool, where the determining includes specifying a first physical property for a first subset of the plurality of repeating structures, and specifying a different second physical property for a second subset of the plurality of repeating structures.

The machine-readable instructions include tool digital representation generation instructions606to generate a digital representation of the tool, the digital representation including information specifying the first physical property for the first subset of the plurality of repeating structures, and specifying the second physical property for the second subset of the plurality of repeating structures.

In some examples, machine-readable instructions can detect different orientations of a first surface and a second surface of the tool. The machine-readable instructions can specify a first size of a first repeating structure on the first surface, and specify a different second size of a second repeating structure on the second surface. The machine-readable instructions includes, in the digital representation, information specifying the first size of the first repeating structure and information specifying the second size of the second repeating structure, where the first repeating structure and the second repeating structure when built by an additive manufacturing machine have substantially a same size (e.g., sizes within 1% of one another, or sizes within 2% of one another, or sizes within 5% of one another, or sizes within 10% of one another, etc.).

A hardware processor that can execute the machine-readable instructions can include a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, or another hardware processing circuit.