Conventional powder supply and build bins in solid freeform fabrication (SFF) systems include vertical walls attached to the working surface of the SFF machine and a permanent bottom plate that is height-controlled throughout the build process. The bottom plate of the powder-source bin increments upward during the build process to provide additional powder that can be spread above a build plate in the build bin. The build plate is simultaneously incremented downward to accept a new layer of build powder. Regardless of the size of the desired prototype, or build, a volume of powder to fill the entire build bin to the height of the parts being built is required. This can sometimes limit the ability of a user to produce parts with limited powder on-hand.
One issue with binder-powder SFF systems is the amount of time spent between print jobs in the management of the powder in the system. Specifically, parts are typically dug out of build bins or the excess powder vacuumed away, the waste bins are emptied, and supply powder bins are refilled.
Once a build project is completed, the SFF machine remains idle while parts are removed from the build bin. Since the parts that have just been built are typically surrounded on all sides by bulk powder, this process can be very slow as the user brushes or vacuums powder away a little at a time, searching for the recently-fabricated part(s). This process is time-consuming, and is extended even longer if parts require a “dry time” prior to removal from the supporting powder. Once the removal process is started, the solid freeform fabrication machine cannot be further utilized until this process is complete. The removal of parts from the supporting powder is performed directly at the machine, where powder is difficult to contain and, again, may be breathed by the operator. Typically, a vacuum is required to recover powder scattered on the SFF system's working surface.
If the operator desires to change out the powder in the supply bin, then both the powder supply bin and the build bin must be completely cleaned to prevent cross-contamination of powders. This process is manual, requiring the user to scoop, brush, and vacuum powder from the bins prior to pouring new powder into the source bin.
It would be desirable to have a solid freeform fabrication system that is easier and less messy to use, and would have less down-time for set up, powder dig-out, and powder change-out processes.
Many aspects of this disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale. Moreover, in the drawings, like reference numerals designate corresponding, but not necessarily identical, parts throughout the several views.
The disclosed solid freeform fabrication (SFF) systems have incorporated therein a convenient supply powder and build bin packaging. The supply powder bin and/or build bin can include a removable top, four side walls, a piston-like bottom that supports the powder and allows a printer piston to feed powder to the spreader during the printing and object fabrication process, and features that easily locate/attach/register the bin with the SFF system. The disclosed bins can be either disposable or reusable and are configured to be interchangeable within the SFF system. The disclosed bins simplify the set-up process, as well as reduce the powder spillage and the required clean up associated with three-dimensional (3D) printing and selective laser sintering (SLS) processes.
Having thus generally described the disclosed SFF systems, reference will now be made to the figures.
In the SFF system 100 of
The powder becomes bonded in the areas where the adhesive or binder is deposited, thereby forming a thin layer of the desired product. After each layer of the 3D object is fabricated, the build bin 102 (in which the object sits) is repositioned downward along the z-axis so that the next layer of the object can be formed on top of the previously formed layer. By way of example, the build bin 102 can have dimensions such as 8″×10″×10 or 6″×6″×6″ to accommodate fabricators and 3D objects of various sizes.
The process is repeated with a new layer of powder being applied over the top of the previous layer in the build bin 102. The next cross section of the desired product is then printed with adhesive or binder into the new powder layer. The adhesive also serves to bind the adjacent or successive layers of the desired product together. A user interface or control panel 104 can be provided to allow the user to control the fabrication process.
This process continues until the entire object is formed within the powder bed in the build bin 102. The build bin 102 can be removed from the SFF system 100 so that the fabricated object can be removed from the build bin 102 outside of the SFF system 100. The extra powder that is not bonded by the adhesive is then brushed or vacuumed away leaving the base or “green” object.
The SFF system 100 also includes a controller (not shown) which is programmed to, among other things, control the positioning and repositioning of the print head 103 during the 3D object fabrication process. The controller can take the form of a discrete module positioned proximate to the print head; alternatively, the operations performed by the controller can be distributed among a plurality of controllers, processors or the like, and/or the controller can be remotely located relative to the print head.
Such a printing process offers the advantages of speedy fabrication and low materials cost. It is considered one of the fastest solid freeform fabrication methods, and can be performed using a variety of colors.
The print head in the SFF system 100 can include inkjet technology for ejecting a binder or adhesive on a powder layer to form the layers of the desired object. In inkjet technology, the print head ejects drops of binder in a selective pattern to create the image being printed, or in the case of solid freeform fabrication, to color the object being fabricated. As used herein and in the attached claims, the term “binder” is used broadly to mean any substance ejected by a print head to form an object being fabricated. Consequently, the term “binder” includes, but is not limited to, binders, adhesives, etc. The binder can be, for example, clear (to create non-colored parts) or colored (to create colored objects or parts of objects).
As shown in
Alternatively, or in addition, the build bin 102 can include vertical registration components such vertical pins with hardened points on the tips, located in the system 100, that contact either the bottom surface 118 or the flanges 122 or lip around the bin 102. Use of registration components minimize the possibility of powder interfering with the registration interface. Further, the bin 102 can include one or more seating sensors (not shown) to detect when the bin 102 is properly seated in the system 100. Seating sensor(s) can be, for example, an electrical continuity check, a Hall effect sensor, a through-beam or reflected light sensor, and/or a high precision switch. In addition, the seating sensor can also include mechanical or electrical lockout features to ensure use of materials that are compatible with the SFF system.
In one embodiment, the linear motion actuator 119 pulls downward on the bottom moveable platform 118, which fits exactly inside the side walls 116 of the build powder bin 102. In one embodiment, the build bin 102 has a pair of lower flanges 120 that extend beneath and parallel to the bottom moveable platform 118, on which the platform 118 rests when the build bin 102 is full of powder and the fabricated part(s), as shown in
As depicted in
The optional removable lid 114 can be, for example, a lid that peels back, or even completely off, slides on or off, or that snaps onto and off of a lip (not shown) of an upper surface of the build bin 102. The lid can also be designed, as in a snap-fit lid, to be re-installed after fabrication of an object so that the build bin 102, when full of powder and the fabricated object, can be removed from the system 100 with minimal risk of spilling the powder and/or creating airborne powder migration. The lid can be opened and/or removed either manually or by components in the SFF system 100.
The material of the build bin 102 can be any material that is sufficiently rigid to support a bin full of powder or slurry. For example, the material can be a metal or metal alloy, cellulosic material, or hard, stiff plastic (e.g., thermosets and thermoplastics, including for example, acetals, acrylics, terpolymers, alkyds, melamines, phenolic resins, polyarylates, polycarbonates, high density polyethylene, polyphenylene sulfide, polystyrene, polyvinyl chloride, styrene acrylonitrile, polyphenylsulfone, sulfones, unsaturated polyesters, polypropylene, polytetrafluoroethylene, polyethersulfone, polyetherketone, liquid crystalline polymers, or urea-formaldehyde molding compounds, etc.). The material of the build bin 102 can also include fillers for the polymers, the fillers being designed to be compatible with each polymer. The fillers can impart various properties to the polymeric material, such as increased strength. The build bin 102 can be designed to be either disposable or reusable, depending on the material selected for the build bin 102. In addition, in one embodiment, the build bin 102 includes low friction surfaces on side walls 116, whereby powder contained in the build bin 102 slides easily along the bin walls throughout the fabrication process.
The bag compartment 132 includes an optional crinkle zone 133 that enables the bag to fold easily as a platform 140 and the actuator 119 operate on the bag compartment 132 in the z-direction. In the embodiments employing a bag compartment 132, the space/clearance between the bag compartment 132 and side walls in a build bin housing 144 is large enough to accommodate collapsed folds of the bag compartment 132.
The platform 140 and actuator 119 can be already in place in the system 100, and the build bin 105 is inserted to rest on top of the platform 140. The actuator 119 in one embodiment can have optional struts 142 to stabilize the actuator 119 during movement. The struts 142 can be, for example, a stiff metal, metal alloy, or a hard plastic material.
The build bin 105 can have a pair of upper flanges 122 that extend beyond the side walls. The upper flanges 122 engage an upper surface 124 of the bin housing 126 and aid in placement of the build bin 105. Preferably, the upper flanges 122 are of a stiffer material than the bag compartment 132 in order to aid in proper placement of the bag compartment 132. The upper flanges can be made of, for example, a cellulose-based material (e.g., cardboard), a metal, or a hard plastic.
In one embodiment, the linear motion actuator 119 pulls downward on the platform 140, which fits exactly inside the side walls of the build bin housing 144 in the system 100. As depicted in
The optional removable lid 114 can be, for example, a lid that peels back, or even completely off, or that snaps onto and off of a lip (not shown) of an upper surface of the build bin 105. The material of the bag compartment 132 can be any material that is sufficiently rigid to support a bin full of powder or slurry, yet sufficiently pliable to unfold upon expansion caused by the lowering of the actuator 119 and platform 140. The bag compartment is chosen to provide a barrier to environmental conditions such as, for example, air, humidity, moisture, grease, and/or light, etc. For example, the material of the bag compartment 132 can be any flexible polymeric material. These include but are not limited to flexible films of polyvinyl chloride, polyvinylidene, polyethylene, polyethylene copolymers, polyethylene naphthalate, polyester, polyamide, polyarylates, polybutylene terepthalate, polypropylene, polyurethane, cellulosics, and polysaccharides. The build bin 105 can be designed to be either disposable or reusable, depending on the material selected for the build bin 105. By using a bag compartment 132 for the build bin 105, the tolerance between the platform 140 and the side walls of the bin housing 144 can be reduced, as well as eliminating the need for o-rings that are typically used to create a tight seal.
By using a removable build bin, unused powder that is contained in the build bin can be easily removed from bin while the bin is outside of the solid freeform fabrication system. The build bin can be reused at a later time, for example as a supply bin 110 (once the fabricated object has been removed), or the powder recycled from the build bin for other uses. Thus, in one embodiment of the system 100, the supply bin 110 and the build bin are configured to be interchangeable. For example, the supply and build bins can both be removable, and be of the same size and shape to allow each one to fit into a housing for the other one.
In addition, as illustrated by
The solid freeform fabrication system 100 can include a sensor that is capable of reading the memory mechanism 146. For example, in the case of an IC chip, the system 100 can use information from the build bin in tandem with the information from the inkjet supply's memory chip to ensure, for example, that the correct binder liquid and powder are mixed. The system 100 can also use the data encoded in or on the memory mechanism 146 to determine certain operating parameters, such as for example, print speed, drop volume per voxel, color maps, dry time needed after build completion, shrink or expansion size, adjustment factors, powder settling coefficients (e.g., to determine whether powder supports need to be included, and if so, how much support), minimum allowable layer thickness, etc.
Communication with the IC can be via contact pads or wireless via radio frequency signals. Generally the bar codes are read only, whereas the IC can be written to. The memory mechanism 146 can be placed anywhere on the build bin, so long as it can be read by a sensor in or on the SFF system 100.
The build bin 102 can include a handle 148. The handle 148 can be in any configuration (e.g., square or semicircular) and can be removable, collapsible, telescoping, and/or magnetic. In addition, the handle can be a notch or set of notches, inset into the build bin 102 or 105. The build bin is designed so that it can be removed from the system 100 by grasping and pulling on the handle 148, or inserting a removable handle into the features provided.
In other embodiments of the system 100, the bins include features that allow attachment to other pieces of the system 100 for further processing. For example, the bins can include features for attachment to other equipment such as, for example, a dryer, a de-powdering station, a powder refill station, a powder packaging station (for either reusable powder or for packing fresh containers after shipping), etc.
Also disclosed are methods of solid freeform fabrication, using the disclosed build bins.
Many variations and modifications may be made to the above-described embodiments. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.
This application is related to U.S. utility patent application Ser. No. 11/191,797 (HP Docket No. 200406140-1), filed on Jul. 28, 2005.