Patent Application
20160200046
1. Technical Field
Apparatus and methods for fabricating objects or parts by additive manufacturing. More particularly, an apparatus and method for fabricating a part by forming the part in a sequence of layers, each of the layers transferred and joined to the partially formed part in a single step over a large area of the part.
2. Description of Related Art
Recent advances in microelectronics, material compositions, and material processing on a microscale have enabled new object fabrication methods. Such fabrication methods typically involve the creation of a digital or “virtual” three-dimensional model of the object to be fabricated, which is then uploaded to fabrication process equipment that may fabricate the object as a series of two dimensional layers. Such fabrication processes, which include fused deposition modelling, selective laser melting, direct metal laser sintering, and selective laser sintering, are often referred to as additive manufacturing or “3-D printing.”
In the field of 3-D printing, many approaches such as fused deposition modelling, selective laser melting, direct metal laser sintering, and selective laser sintering have been used to create a desired object. However, throughput remains a major drawback of these current approaches. For a part of even modest complexity, many hours are often required to produce the part. One approach to increasing fabrication speed is to adapt a process used in xerography, by which thin layers of powder (similar to a xerographic toner) are generated as the material from which to create the 3-D part. Methods and apparatus for such fabrications are disclosed in the Applicant's commonly owned U.S. Pat. No. 8,771,802, entitled, “Device and Materials Fabrication and Patterning Via Shaped Slot Electrode Control of Direct Electrostatic Powder Deposition,” the disclosure of which is incorporated herein by reference.
Although such methods and apparatus can generate the layers quickly, significant major problems remain in the “build” part of the 3-D process. One problem is the accumulation of residual charge in the layers of powder of the part being fabricated. Using conventional electrostatic transfer of powder to build up a three-dimensional object is not feasible, since the quantity of charge accumulated in the part after a few transfers of layers causes substantial reduction and even complete loss of the transfer field. Attempting to discharge the transferred powder after each layer transfer does not solve the problem, because after multiple transfers of layers, establishing an effective transfer field across a thick plastic part in order to cause discharge also becomes difficult.
Another countermeasure, discharging the powder before transfer to the 3-D part, reduces the options for subsequent layer transfer approaches to few, such as utilizing heat and pressure to fuse the powder particles into a solid layer. Heat may be effectively used; however, heat transfer through a powder layer is a slow process occurring primarily by conduction, and must be carefully managed, particularly when large plastic parts are being fabricated. Heating to fuse the particles becomes the rate-limiting step in this particular approach to 3-D printing, typically requiring several seconds per transfer and thereby negating the increased throughput obtained by using xerographic methods to generate the powder for layer deposition.
In an additive manufacturing process in which a part is fabricated by deposition and fusion of sequential layers of powder, there remains a need for a method of rapidly depositing a sequence of powder layers, and rapidly fusing them into solid layers, so that the overall part is made at a rapid throughput and with the required dimensional accuracy.
The present invention meets this need by providing an apparatus for forming a part, comprising a substrate for holding the part during forming; a transport web; a transport web delivery system; a powder imaging system configured to deposit a sequence of imaged layers of powder defining cross sections of the part on a sequence of areas of the transport web delivered by the web delivery system; a sintering station configured to sinter the sequence of imaged layers of powder on the transport web to form a sequence of sintered powder layers defining the cross sections of the part, the sequence of sintered powder layers comprising a first sintered powder layer, intermediate sintered powder layers, and a last sintered powder layer; and a transfer station comprising a vibratory horn movable relative to the support substrate to form a transfer nip within which the first of the sintered powder layers is fuseable upon the support substrate to form a first fused layer, and each of the intermediate sintered powder layers is fuseable to a preceding fused layer, and the last sintered powder layer is fuseable to a last preceding fused layer, wherein fusing of the sequence of sintered layers form the part.
The transport web may be deliverable by the web delivery system along a delivery axis, with the vibratory horn being comprised of an elongated distal end contactable with the transport web and having a longitudinal axis transverse to the delivery axis of the web. The apparatus may be further comprised of a compliant material joined to a distal end of the vibratory horn. The apparatus may be further comprised of a reciprocator configured to move the support substrate synchronously with motion of the transport web. The powder generation may be a xerographic toner powder generation system.
In accordance with the present disclosure, there is also provided a method for making a part. The method comprises depositing a first layer of powder on a transport web substrate; sintering the first layer of powder to form a first sintered layer on the transport web substrate; conveying the first sintered layer to a location proximate to a support substrate; contacting a vibratory horn with the transport web substrate at the location of the first sintered layer on the transport web substrate, and moving the vibratory horn to cause the transport web substrate and first sintered layer to move to a location wherein the first sintered layer is in contact with the support substrate; and oscillating the vibratory horn at a frequency to cause fusing of the first sintered layer into a first fused layer of the part, the first fused layer removably joined to the substrate.
For a part comprised of at least two layers, the method further comprises depositing a second layer of powder on the transport web substrate; sintering the second layer of powder on the transport web substrate to form a second sintered layer on the transport web substrate; conveying the second sintered layer to the location proximate to the support substrate; contacting the vibratory horn with the transport web substrate at the location of the second sintered layer on the transport web substrate, and moving the vibratory horn to cause the transport web substrate and second sintered layer to move to a location wherein the second sintered layer is in contact with the first fused layer; and oscillating the vibratory horn at a frequency to cause fusing of the second sintered layer into a second fused layer of the part joined to the first fused layer of the part.
For a part comprised of a sequence of layers, the method further comprises depositing a sequence of layers of powder on the transport web substrate; sintering the sequence of layers of powder on the transport web substrate to form a sequence of sintered layers on the transport web substrate; for each layer of the sequence of sintered layers, conveying that layer of the sequence of sintered layers to the location proximate to the support substrate; for each layer of the sequence of sintered layers, contacting the vibratory horn with the transport web substrate at the location of that sintered layer on the transport web substrate, and moving the vibratory horn to cause the transport web substrate and that sintered layer to move to a location wherein that sintered layer is in contact with a preceding fused layer; and oscillating the vibratory horn at a frequency to cause fusing of that sintered layer into an additional fused layer of the part joined to the preceding fused layer of the part.
The method may further comprise disposing a compliant layer between the vibratory horn and the transport web substrate. Such a method may further comprise moving the support substrate and at least the first fused layer of the part synchronously with motion of the transport web substrate while contacting the vibratory horn with the transport web substrate at the location of one of the sintered layers on the transport web substrate, and moving the vibratory horn to cause the transport web substrate and one of the sintered layer to move to a location wherein the one of the sintered layers is in contact with the support substrate or a preceding fused layer, and oscillating the vibratory horn at a frequency to cause fusing of the one of the sintered layers into an additional fused layer of the part. The method may further comprise moving the transport web substrate and first sintered layer of the part in a direction that is transverse to the longitudinal axis of a distal end of the vibratory horn that is contacted with the transport web substrate.
The sintering may be performed by at least one of heating the first portion of the powder on the transport web substrate and exposing the first portion of the powder on the transport web substrate to a solvent. The method may further comprise generating the first portion of powder using a xerographic toner powder generation process prior to depositing the first layer of the powder on the transport web substrate. In certain embodiments, the vibratory horn may be oscillated at a frequency of between 15 kHz and 40 kHz.
In accordance with the present disclosure, there are provided alternative apparatus and methods for fabricating a part, by using “far-field” welding of powder layers. The apparatus is comprised of a support plate, a transport web delivery system, a powder imaging system, a sintering station, and a transfer station. The powder imaging system is configured to deposit a sequence of imaged layers of powder on a sequence of areas of the transport web delivered by the web delivery system. The sintering station is configured to sinter the sequence of imaged layers of powder on the transport web to form a sequence of sintered powder layers, the sequence of sintered powder layers comprising a first sintered powder layer, intermediate sintered powder layers, and a last sintered powder layer. The transfer station is comprised of a backing member and vibratory transducer coupled to the support plate. The vibratory transducer and support plate are movable toward the transport web and backing member to form a first layer transfer nip within which the first of the sintered powder layers is fuseable upon the support plate to form a first fused layer. Additionally, the vibratory transducer, support plate, and first and subsequent fused layers are movable toward the transport web to form an intermediate transfer nip within which each of the intermediate sintered powder layers is fuseable to a preceding fused layer; and the vibratory transducer, support plate, and first and intermediate fused layers are movable toward the transport web to form a last transfer nip within which the last sintered powder layer is fuseable to a last preceding fused layer, wherein fusing of the sequence of sintered layers form the part.
The transfer nips are formed between the transport web and a part receiving surface of the support plate. In certain embodiments of the apparatus, the vibratory transducer may be coupled to the part receiving side of the support plate. In other embodiments, the vibratory transducer may be coupled to the part receiving side of the support plate.
In certain embodiments, the backing member is movable laterally along the transfer web to cause the transfer nip to move laterally relative to the part. Such a backing member may be a cylinder having an axis of rotation parallel to a plane defined by the support plate, which cylinder may be rotatable around its axis of rotation while translating laterally along the transfer web. The cylinder may be comprised of a compliant outer layer.
In a method of making a part using the above apparatus that utilizes far-field welding, the method comprises depositing a first layer of a powder on a transport web substrate; sintering the first layer of powder to form a first sintered layer on the transport web substrate; conveying the first sintered layer to a location proximate to a support plate; coupling a vibratory transducer to the support plate and moving the vibratory transducer and support plate toward the transport web substrate to form a first layer transfer nip at an edge of the first sintered layer and between a backing member and the support plate; oscillating the vibratory transducer at a frequency to cause fusing of the first sintered layer into a portion of a first fused layer of the part within the nip; and moving the backing member laterally along a plane parallel to the plane defined by the support plate to cause the nip to move laterally along the first sintered layer and cause the first sintered layer to fuse, forming the first fused layer removably joined to the substrate.
For adding a second layer to the part, the method further comprises depositing a second layer of powder on the transport web substrate; sintering the second layer of powder on the transport web substrate to form a second sintered layer on the transport web substrate; conveying the second sintered layer to a location proximate to the first fused layer; moving the vibratory transducer, support plate, and first fused layer toward the transport web substrate to form a second layer transfer nip at an edge of the second sintered layer and between the backing member and the first fused layer; oscillating the vibratory transducer at a frequency to cause fusing of the second sintered layer into a portion of a second fused layer of the part within the nip; and moving the backing member laterally along the plane parallel to the plane defined by the support plate to cause the first layer transfer nip to move laterally along the second sintered layer and cause the second sintered layer to fuse, forming the second fused layer joined to the first fused layer.
For adding a sequence of additional layers to the part, the method further comprises depositing a sequence of layers of powder on the transport web substrate; sintering the sequence of layers of powder on the transport web substrate to form a sequence of sintered layers on the transport web substrate; and for each layer of the sequence of sintered layers, conveying that sintered layer to a location proximate to the preceding fused layer; moving the vibratory transducer, support plate, and fused layers toward the transport web substrate to form an additional layer transfer nip at an edge of that sintered layer and between the backing member and the preceding fused layer; oscillating the vibratory transducer at a frequency to cause fusing of that sintered layer into a portion of an additional fused layer of the part within the nip; and moving the backing member laterally along the plane parallel to the plane defined by the support plate to cause that layer transfer nip to move laterally along that sintered layer and cause that sintered layer to fuse, forming the additional fused layer joined to the preceding fused layer of the part.
In certain embodiments, the vibratory transducer may be oscillated at a frequency of between 15 kHz and 40 kHz.
In other embodiments of the apparatus using far-field welding, the backing member may be comprised of a conformable pressure plate contactable with an entire area of the web substrate opposed to an upper surface of the part when receiving an intermediate or last sintered layer of the part. In a method of making a part using such an apparatus, the method comprises depositing a first layer of a powder on a transport web substrate; sintering the first layer of powder to form a first sintered layer on the transport web substrate; coupling a vibratory transducer to a support plate; conveying the first sintered layer to a location between the support plate and a pressure plate comprising a conformable compression member; moving the pressure plate toward the transport web substrate to cause the entire first sintered layer to contact the support plate and cause the conformable compression member to contact an entire area of the web substrate in contact with the first sintered layer; and oscillating the vibratory transducer at a frequency to cause the first sintered layer to fuse into a first fused layer removably joined to the substrate.
For adding a second layer to the part, the method further comprises depositing a second layer of powder on the transport web substrate; sintering the second layer of powder on the transport web substrate to form a second sintered layer on the transport web substrate; conveying the second sintered layer to a location between the first fused layer and the pressure plate; moving the pressure plate toward the transport web substrate to cause the entire second sintered layer to contact the first fused layer and cause the conformable compression member to contact an entire area of the web substrate in contact with the second sintered layer; and oscillating the vibratory transducer at a frequency to cause the second sintered layer to fuse into a second fused layer joined to the first fused layer.
For adding a sequence of additional layers to the part, the method further comprises depositing a sequence of layers of powder on the transport web substrate; sintering the sequence of layers of powder on the transport web substrate to form a sequence of sintered layers on the transport web substrate; and for each layer of the sequence of sintered layers, conveying that sintered layer to a location between the preceding fused layer and the pressure plate; moving the pressure plate toward the transport web substrate to cause that entire sintered layer to contact the preceding fused layer and cause the conformable compression member to contact an entire area of the web substrate in contact with that sintered layer; and oscillating the vibratory transducer at a frequency to cause that sintered layer to fuse into an additional fused layer joined to the preceding fused layer.
The present disclosure will be provided with reference to the following drawings, in which like numerals refer to like elements, and in which:
The present invention will be described in connection with certain preferred embodiments. However, it is to be understood that there is no intent to limit the invention to the embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. In the following disclosure, the present invention is described in the context of its use in transwelding plastic powder materials. However, it is not to be construed as being limited only to use in welding plastic powders. The invention is adaptable to any use in which fusion of powders of solid materials is desirable in order to form a solid object, including plastic powders, metal powders, and mixtures of powders of plastics, metals, and other friable materials.
Additionally, in the present disclosure, certain components may be identified with adjectives such as “top,” “upper,” “bottom,” “lower,” “left,” “right,” etc. These adjectives are provided in the context of the orientation of the drawings, which is arbitrary. The description is not to be construed as limiting the various apparatus disclosed herein to use in a particular spatial orientation. The instant apparatus may be used in orientations other than those shown and described herein.
It is also to be understood that any connection references used herein (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily imply that two elements are directly connected and in fixed relation to each other.
As used herein, the term “powder” is meant to indicate any solid material that has been subdivided into small particles, which are sufficiently small so as to render them flowable by mechanical action or fluidization with a gas. The particles of a powder may be spherical, oblong, or of various other geometrical shapes such as crystalline shapes, and may be of a non-uniform size distribution.
As used herein, the term “transwelding” is meant to indicate a process operation in which a first material, which is conveyed by, for example, a donor web, is contacted with the surface of a second material, and is fused with that second material by applying a welding device having a width greater than, or at least equal to the width of the surface of the second material in a manner such that the welding of the first material to the second material occurs over the entire width of the surface of the second material.
As used herein, the term “ultrasonic” in reference to an energy source is meant to indicate a mechanical source of energy imparted by oscillations of a vibrating member at a frequency of between 15 kHz to 40 kHz. In certain embodiments of the apparatus and methods disclosed herein, operation at frequencies outside of this range may be operable.
Several embodiments of apparatus and methods for transwelding plastic powder are disclosed herein. Referring to
In a first operation of the fabrication of part 10, a sequence of layers of powder are transferred to the transport web 30, which is movable as indicated by arrow 99. In certain embodiments, the powder may be transferred to the transport web 30 by methods used in electrophotographic imaging, such as electrostatic transfer of xerographic toner, which is a type of ink in powder form. Such methods and related apparatus are described in commonly owned U.S. provisional patent Application No. 62/103,269, the disclosure of which is incorporated herein by reference. Thus in such embodiments, each of the layers of powder in the sequence of layers is “imaged” onto the transport web 30, transported to a location proximate to the support substrate 70, and transferred as a sequence of layers 10A, 10B, and 10D onto the support substrate 70 to form the overall part 10. In certain embodiments, the toner may be an acrylonitrile butadiene styrene (ABS) toner. Following deposition of the toner as one of the layers 10A, 10B, or 10D of the part, the toner layer may be electrically discharged by various discharge means used in xerography. In other embodiments, the powder may be deposited on the transport web using an apparatus and method as disclosed in the aforementioned U.S. Pat. No. 8,771,802.
The transport web 30 may be operated with continuous motion, or with intermittent motion, i.e., an indexed motion having starts and stops. In the embodiment depicted in
With the powder of layer 10D in contact or close proximity with the uppermost layer 10C of part 10, the ultrasonic horn 50 is operated by a control system 51. Ultrasonic energy is imparted into the powder of layer 10D, causing it to be transwelded, i.e., transferred to and fused with the uppermost layer 10C of part 10. The ultrasonic horn 50 is then retracted, and the transport web 30 is indexed again to advance region 25 of the web 30 conveying another portion of powder 10E to be added to the part 10.
In certain embodiments, the powder to be added to the part 10 as a layer may be sintered on the transport web 30, prior to it being added to the part 10. The Applicants have discovered that such an operation is beneficial in that it solves the problem of airborne dispersal of the powder during the ultrasonic transwelding of the powder to the part 10, which often occurs if sintering is not done. In certain initial studies of the joining of layers of plastic to form a part, ultrasonic welding of thin sheets of plastic was performed. Subsequently, ultrasonic welding of ABS toner (powder) was attempted instead of welding of thin solid sheets. In making such attempts to ultrasonically weld powder, the problem of airborne dispersal of the powder was discovered: significant amounts of ABS toner were observed being ejected from the nip between the ultrasonic horn and the substrate. Repeated experiments at various process conditions led to the conclusion that the ultrasonic vibrations from the ultrasonic horn were quite powerful with respect to the toner, and were causing the ejection from the nip and dispersion into the nearby air.
As a countermeasure, the Applicants hypothesized that it would be beneficial to temporarily adhere the toner to the donor surface by some suitable means. Tacking the toner to the donor sheet via some mild heating was tried using a hot plate and that appeared to solve the problem. Subsequently, upon microscopic observation and with more controlled experiments, it became apparent that sintering was the most desirable way of adhering the toner to the donor surface, and, combined with using a low surface energy donor material (e.g., the donor material of transport web 30 of
To accomplish sintering of the powder on the transport web 30, a heater may be provided, such as a heating element (not shown) that may be in contact with the transport web on the side that is opposite of the side that is conveying the powder. In the embodiment depicted in
In one exemplary embodiment, an ABS toner was used as a powder material. Prior to transfer of layers of the toner to form the part 10, the powder layers were heated to about 130° C. to achieve sintering. The resulting sintered layers were allowed to cool to room temperature before transwelding. It was discovered that in some instances, the sintering process may cause the toner to adhere to the transport web 30; however, the toner layer needs to release from the transport web 30 during the transwelding process in order to form the particular layer on the part 10. In order to meet this requirement, the transport web 30 may be made of a suitable low surface energy material, such as Teflon® FEP fluoropolymer-coated Kapton®. Other materials are contemplated, with the operative requirement that such materials are not degraded or otherwise affected by heat or pressure, or by the ultrasonic energy during the transwelding process.
In certain embodiments, the most rapid part building process using ultrasonic welding employs a full-area weld, creating a “stamp and repeat” approach as described above. If a full-area weld is employed, i.e. if the surface of the ultrasonic horn is planar and large enough to cover the entire part in fabrication, the Applicants have discovered that another problem arises, which is macro uniformity of contact. Even very slight variations (less than 25 μm) in the flatness of either surface (part 10 or ultrasonic horn 50 or plate 52) results in a raised pressure point, which prevents contact to most of the remaining intended weld area, leaving this area un-welded.
In order to solve this problem, a compliance pad or layer 40 may be provided as part of the transwelding station 4. The compliance layer may be provided contiguous with the bottom surface of the end plate 52 of the ultrasonic horn 50. Without wishing to be bound to any particular theory, the Applicants believe that the compliance layer 40 improves macro-uniformity of pressure in the welding nip, i.e., the portion of the transport web 30 that releases the sintered layer portion to the part 10 during transwelding to add another layer to the part 10. Thus for compliant layer 40, the Applicants select a material that is soft or compliant in the time frequency domain of the ultrasonic nip dwell time (e.g., 0.1-2 sec), but stiff or non-compliant in the ultrasonic frequency time domain (e.g., 0.01-0.10 msec).
In certain embodiments, the part 10 may be heated during the transwelding of successive layers 10A and 10B. The heating may be provided by a heater (not shown) that heats the support substrate 70. The Applicants believe that with some powders, heating of the part 10 facilitates the fusing of the powder into a new layer during transwelding. The temperature of heating is chosen depending upon the particular powder material that is being transwelded.
In one exemplary embodiment, a transwelding apparatus 1 with the following features was provided having a support substrate 10 with a heater for heating the part 10 during transwelding, and a sheet of nitrile rubber, 112 microns (μm) thick, and of durometer 30 Shore A, as a compliant layer 40. Experimental trials were conducted with this apparatus 1 using an ABS toner to fabricate an ABS part 10. During successive additions of layers, the part 10 was heated to about 95° C. Successful transwelding of additional layers to the part 10 were achieved at various transwelding conditions. Some successful transwelds were achieved using a solid flat-surfaced ultrasonic horn operated at 20 KHz with a 1:1 booster, and 750 Joules of energy applied for 900 milliseconds at 90 pounds per square inch (psi) of nip pressure, i.e., the pressure applied over the surface area of the layer being added to the part. Other successful transwelds with this ultrasonic horn were achieved with conditions of 450 Joules energy, 430 msec of duration and 68 psi of nip pressure. The Applicants believe that other frequencies may be used with appropriately differing set points to accomplish the same results. The thicknesses of the transwelded layers were approximately 25 μm.
In other embodiments, a second powdered material may be co-deposited with the primary powder material that forms the part 10. The second powder material functions as a support polymer. It is used in conjunction with the primary powder material to provide structural support during the fabrication process, and is transwelded along with the primary material. Subsequently, the support polymer may be dissolved or discarded when fabrication is complete, leaving behind the desired part with hollow cavities previously occupied by the second powdered material. In that manner, it is further noted that a layer of powder to be transwelded to the part 10 does not necessarily have to be a uniform layer. The layer may be an irregular layer as shown for irregular layers 10E in
In certain embodiments, the primary powder to be transwelded may include metallic constituents. In certain embodiments, the primary powder may be electrically conductive.
In a method practiced using the apparatus 3 of
The transport web 30 conveys the portions 11C/11D as indicated by arrow 97 to the transwelding station 5, which is comprised of the ultrasonic horn 54 and its ultrasonic drivers and control system 51. The transwelding station 5 is further comprised of a conveyor or reciprocator (not shown), which traverses the support substrate 71 and the part 11 being fabricated along the cyclical path indicated by arrows 96A-96D. The ultrasonic horn 54 may be advanced and retracted to provide proper nip geometry as indicated by bidirectional arrow 95. The motion of the ultrasonic horn 54 and the reciprocating motion of the support substrate 71 and part 11 being fabricated are synchronized with the conveyance of the powder portions that are deposited on the transport substrate 30 so that a powder portion to be added and the part 11 arrive concurrently at the nip and are contacted by the ultrasonic horn 54. For example, referring to
The use of a linear ultrasonic horn 54 with a radiused head 55 provides certain advantages over the apparatus 1 of
In accordance with the present disclosure, an alternative method has been devised to laminate and/or weld a thin layer of plastic to a part being fabricated of the same or a similar material. The method employs ultrasonic vibratory motion to mimic the effect of welding via an ultrasonic horn. However, in contrast to the embodiments disclosed above and depicted in
It is known that an ultrasonic horn focuses vibratory mechanical energy to well-defined regions to effect welding of materials via localized heating. When the ultrasonic horn is a horn 54 as depicted in
As used herein, the term “far field” is meant to indicate that the distance between a source of ultrasonic energy and the area of material being welded to the part being fabricated is at least 6 millimeters. In certain embodiments, distances between 6 mm and 100 mm have been demonstrated to be effective for achieving welding. Although the parameters that are operable for far field ultrasonic welding may be somewhat narrower than conventional direct ultrasonic welding using an ultrasonic horn, the overall far field ultrasonic welding method still permits a viable approach for many 3-D printing systems, or any process that directed to welding very thin layers (approx. 0.001 inch thick), whether in sequential layers or a single layer.
Although the mechanism for far-field ultrasonic welding is likely the same as for conventional ultrasonic welding, the Applicant believes that uniqueness of its applicability in 3-D printing derives from several material properties and procedures, all of which are preferably simultaneously present. Such properties and procedures are as follows:
Based upon the above-described discovery of the far-field welding effect, the Applicant has made an apparatus for use of the effect in fabricating an object. One exemplary embodiment of the apparatus is depicted in
The transport web delivery system 230 is comprised of a transport web 232, a web supply roll (not shown), a web windup roll (not shown), and a web drive (not shown). Alternatively, the transport web 232 may be a loop or belt (not shown) of web material, obviating the need for a web supply roll and web windup roll. The transport web delivery system 230 is further comprised of web rollers 234 and 236 positioned to allow traversal of the web 232 along the surface 13S of the object 13 by backing member 240 during transwelding of the next layer 13X into an additional fused layer added to the object 13. In certain embodiments, the transport web 232 may be a thin sheet metal web, or a web of polyimide polymer such as Kapton®. The web 232 may be further comprised of a fluoropolymer coating such as Teflon® to provide a low surface energy that facilitates release of the powder layers from the web 232 when they are transwelded to form the object 13.
The transport web delivery system 230 sequentially delivers sintered layers of material to be transwelded to the object 13, beginning with a first sintered layer (not shown) that is transwelded into a first fused layer. In the apparatus 200 and method depicted therein, the object 13 is partially formed by transwelding a sequence of fused layers. The web delivery system has indexed the web 232 with the next layer 13X into position to be transwelded. Additionally, the subsequent layer 13Y to be transwelded has been disposed on the web 232. The layers 13X and 13Y may be provided by powder layer forming and sintering devices (not shown) as described previously for the methods and apparatus of
Referring to
The transwelding of the layer 13X to the object 13 is depicted in a partially completed stage in
The support plate 210, vibratory transducer 220, and object 13 are movable vertically as indicated by bidirectional arrow 297 by a drive system (not shown). Thus the plate 210, transducer 220, and object 13 may be lowered to provide clearance between the top surface 13S of the object 13 and the web substrate 232, so that the backing member 240 can be returned to the transwelding starting position of
Repeated transwelding of successive layers are performed to build the object 13. It is noted that at the beginning of building the object 13, the support plate 210 is “empty,” i.e. it is a bare plate with no object material formed on it. In transwelding of the first layer of object 13, the transfer nip is formed between the support plate 210 and the web substrate 232.
In certain embodiments, the backing member 240 may be a cylindrical member as depicted in
In operating the apparatus 200 and 201 of
In the operation of apparatus 202, the web delivery system indexes the web so that a sintered layer 13X is in position for transwelding to the object 13. A conformable pressure plate 250 is advanced downwardly as indicated by arrow 296 from a home position (solid line) to a first position of contact (coarse dotted line) with the portion of the web 232 carrying the layer 13X, and then into a second position of contact (fine dotted line) with the portion of the web 232 carrying the layer 13X. The second position is a compressive position. The conformable pressure plate 250 is made of an elastomeric material that deforms when forced against the web 232, layer 13X and object 13 to be fabricated. In
Once the conformable pressure plate 250 has been moved into the compressive position against the layer 13X and object 13, the vibratory transducer 220 is actuated and delivers ultrasonic energy into the plate 210, the object 13, and layer 13X, and the entire layer 13X is transwelded to the object 13. The vibratory transducer 220 is then stopped, the conformable pressure plate 250 is retracted to its home position, the web substrate is indexed to place layer 13Y in the transwelding zone, and the conformable pressure plate 250 is again advanced to the compressive position. Transwelding of layer 13Y then occurs. The cycle is repeated as many times as needed to build the object 13 in successive layers.
It is further noted that the apparatus 200, 201, and 202 of
It is, therefore, apparent that there has been provided, in accordance with the present invention, a method and apparatus for fabricating an object. Having thus described the basic concept of the invention, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed processes to any order except as may be specified in the claims.
This application claims priority to U.S. Provisional Patent Application No. 62/103,476 filed Jan. 14, 2015, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62103476 | Jan 2015 | US |
