阅读说明：本技术 增材制造方法及设备 (Additive manufacturing method and apparatus ) 是由 滕忆先 于 2018-10-17 设计创作，主要内容包括：本发明是关于一种三维物体增材制造的方法和设备,所述方法和设备被设置成逐层构建成型模,并在其中建造三维物体,此三维物体的层厚等于或大于该成型模的层厚。在不需要粉末床的情况下,该成型模确定所造三维物体的几何形状、尺寸及表面状态,所以在这个增材制造过程中很多单一的或复合的能源及其处理方法可被用来进行熔化、烧结、致密化处理、接合、固化、或者硬化,以处理不同形态和类型的原料,来制造金属、塑料或复合材料物体或工件。(The present invention relates to a method and apparatus for additive manufacturing of a three-dimensional object, the method and apparatus being arranged to build up a mould layer by layer and build up a three-dimensional object therein, the three-dimensional object having a layer thickness equal to or greater than the layer thickness of the mould. The shaping die determines the geometry, dimensions and surface conditions of the three-dimensional object being fabricated without the need for a powder bed, so that many single or complex energy sources and processing methods thereof can be used to melt, sinter, densify, bond, solidify or harden in this additive manufacturing process to process different forms and types of raw materials to fabricate metal, plastic or composite objects or workpieces.)

1. A method of additive manufacturing, the method building a forming die and building a three-dimensional object therein, the method comprising the steps of:

(a) designing a computer-aided design model of a forming die corresponding to the geometric shape of the three-dimensional object;

(b) generating a computer file, the computer file configured to perform a task of an additive manufacturing operation;

(c) providing a device configured to run the computer file and perform the operation;

(d) constructing said forming die at least partially comprised of one or more layers so as to have a cavity formed therein;

(e) placing a raw material in the cavity; and is

(f) Processing the feedstock in the mold cavity to form at least a portion of the three-dimensional object;

repeating the steps (d) to (f) in the process of continuing the operation until the forming die and the three-dimensional object are built.

2. The method of claim 1, wherein the computer file is provided according to a set of cross-sectional geometries cut from a model of the computer-aided design of the formation mold.

3. The method of claim 1, wherein the shaped form is a thin-walled shell form.

4. The method of claim 3, wherein the shell is integrally joined to the three-dimensional object.

5. The method of claim 1, wherein the mold is constructed using a manufacturing process comprising material extrusion, energy-directed melt deposition, material injection, adhesive printing, sheet lamination, machining, or a combination thereof.

6. The method of claim 1, wherein the feedstock is comprised of a single component, multiple components or compositions, and wherein the feedstock is selected from the group consisting of metals, polymers, organics, inorganics, and composites.

7. The method of claim 1, wherein the feedstock comprises a powdered material, a filamentous material, a fibrous material, a sheet material, a wetted fiber bundle, a wetted textile, a liquid composition, or a combination thereof.

8. The method of claim 1, further comprising the step of increasing the density of the feedstock within the die cavity.

9. The method of claim 1, wherein the feedstock is subjected to a treatment with a single or a combination of energy sources within the cavity, the treatment being selected from the group consisting of laser heating, electron beam heating, plasma arc heating, resistance heating, fuel combustion heating, torch heating, electromagnetic induction heating, pressure processing, gas pressure treatment, ultraviolet irradiation, far infrared radiation heating, microwave heating, radio frequency radiation heating, and ultrasonic welding.

10. The method of claim 1, wherein the feedstock is processed within the mold cavity to form the three-dimensional object via melting, sintering, densifying, bonding, solidifying, chemically reacting, hardening, or combinations thereof.

11. The method of claim 1, wherein the feedstock within the cavity is treated with a supply of gaseous or aerosol reactants.

12. An additive manufacturing system configured to build a formation mold and build a three-dimensional object therein, the system comprising:

(a) the computer belongs to the system, and is either a stand-alone computer or a network online computer;

(b) an apparatus configured to build the formation mold layer-by-layer for a geometry corresponding to a set of cross-sections;

(c) a supply device configured to supply a raw material or a plurality of constituent materials into a cavity of at least a part of the molding die that has been built up; and

(d) a processing device or facility configured to process the feedstock within the cavity to shape the three-dimensional object.

13. The additive manufacturing system of claim 12, wherein the apparatus is configured to build the formation mold layer-by-layer using material extrusion, energy-directed melt deposition, material jetting, binder print forming, sheet stacking, machining, or a combination thereof.

14. The additive manufacturing system of claim 12, wherein the apparatus is configured to harden, dry, or cure the formation mold with an energy source during the process of constructing the formation mold.

15. The additive manufacturing system of claim 12, wherein the system is configured to process the feedstock within the cavity with an energy source via a path of melting, sintering, densifying, bonding, chemical reaction, curing, or hardening.

16. The additive manufacturing system of claim 15 wherein the energy source is selected from the following classes for the feedstock treatment, comprising: electromagnetic induction heating, electric arc heating, resistance heating, laser heating, electron beam heating, plasma arc heating, fuel combustion heating, torch heating, ultraviolet irradiation, far infrared radiation heating, microwave heating, radio frequency radiation heating, pressure processing, air pressure treatment, and ultrasonic welding.

17. The additive manufacturing system of claim 12, wherein the system is configured to treat the feedstock with an ambient atmosphere substantially reduced in oxygen.

18. The additive manufacturing system of claim 12, wherein the system is configured to treat the feedstock with an ambient atmosphere of a protective gas.

19. The additive manufacturing system of claim 12, wherein said system is further equipped with a robot for building said forming die, providing said feedstock, processing said feedstock, or building said three-dimensional object.

20. The additive manufacturing system of claim 12, wherein the system has a frame-type assembly structure, a robot hand, or a combination of both to enable XYZ axial movement operations.

Technical Field

The present invention relates generally to a method of manufacturing and more particularly, but not by way of limitation, to a method of manufacturing a three-dimensional object within a layer-by-layer, circumferentially enclosed structure that defines the geometry and dimensions of the three-dimensional object during its formation. The closed structure is essentially a layer-by-layer build-up mold of geometry corresponding to a set of cross-sections into which the material is added to build up the three-dimensional object.

Background

A vast number of manufacturing processes and equipment have been utilized in various industries over the past century. 3D printing, i.e., additive manufacturing, has become increasingly popular as opposed to traditional subtractive manufacturing techniques, such as machining, which occurred thirty years ago. This new manufacturing approach eliminates the need to manufacture conventional molds and provides a variety of methods of rapid prototyping and manufacturing using computer-aided design files to manufacture workpieces from plastic, metal and other materials.

The relationship of high melting point and complex compositional handling organization properties makes metal additive manufacturing a challenging task. Defects or quality failures such as internal porosity, oxidation, undesirable microstructure, unsatisfactory or anisotropic properties, residual thermal stress, distortion, cracking, dimensional deviations, and surface roughness are frequently problems. These problems are often influenced by process parameters and technical capabilities. As a result, it is difficult to establish an appropriate degree of confidence in process qualification and process control to deliver consistent, satisfactory quality.

At present, the additive manufacturing of metal parts is mainly carried out by metal powder technology, such as selective laser melting of a powder bed, selective electron beam melting of the powder bed, printing and forming of a powder bed binder, and extrusion forming of powder paste containing the binder. These powder bed techniques require the use of large amounts of expensive metal powder, cleaning the parts in subsequent processing, collecting the loose powder, carefully recycling and reusing the used powder material, avoiding problems of impurity incorporation, oxidation and safety hazards. In some instances, the loose powder collected cannot be reused, resulting in waste of expensive materials.

Powder bed laser or electron beam selective melting is very costly to manufacture due to the fact that the thickness of the layers is typically in the range of 40 to 70 microns, which is generally very slow, low throughput and high price of raw materials. The metal powder molding technology of organic binder is used to produce low density Green Parts, which may have linear shrinkage as high as 20% in the subsequent sintering process, resulting in difficulty in controlling shrinkage uniformity, geometric deviation, dimensional accuracy and consistency of the process. In addition, the residual organic binder after the "Debinding" step needs to be burned off in the presence of oxygen during sintering. However, burning it out is difficult to control because of a complex balance between avoiding oxidation of the metal powder and leaving behind carbon residue in the metal parts.

The additive manufacturing techniques described above are generally only suitable for manufacturing small metal parts due to low productivity, high cost and limited process capability. For this reason, new methods for additive manufacturing of larger parts are needed, with the speed increased and the cost reduced, using materials not limited to metals but also plastics and composites.

Disclosure of Invention

It is an object of the present invention to provide an additive manufacturing method and system that enables building a forming die including a shell die and building a three-dimensional object therein.

It is another object of the invention to provide an additive manufacturing method and system that can produce small to large three-dimensional objects or workpieces with increased speed and reduced cost.

The object of the invention further consists in providing a method and a system for additive manufacturing using powdered materials, mixed materials of different composition, or raw materials of different morphology for the manufacture of metal, plastic and composite workpieces. The powder bed, binder printing, powder cleaning and collection, binder removal, binder burnout, and subsequent sintering steps are eliminated.

It is yet another object of the present invention to provide an additive manufacturing method and system configured to treat raw materials with specific energy sources, ingredient formulations, or conditions within a mold to achieve melting, sintering, agglomeration, bonding, reaction, or hardening during the formation of a three-dimensional object to achieve desired microstructures, ingredients, and properties.

To the accomplishment of the foregoing and related ends, the invention may be embodied in the form as exemplified in the accompanying drawings. It should be noted that these figures are merely exemplary. The invention should be construed to include modifications within the scope as defined in the appended claims.

Drawings

The invention may be more fully understood by reference to the following detailed description and appended claims, taken in conjunction with the accompanying drawings in which:

fig. 1 is an exemplary process flow diagram of a manufacturing method of the present invention.

Fig. 2a to 2d are schematic diagrams of the structure and operation of the apparatus in some embodiments of the invention.

Detailed Description

The present invention generally relates to a method and apparatus for additive manufacturing of a three-dimensional object, the method and apparatus being arranged to build a forming mould layer by geometry corresponding to a set of cross-sections, to provide raw material to the interior thereof and to process to form the three-dimensional object. The mold or part of the mold exhibits a closed-perimeter configuration during its construction, such that a cavity is formed therein for molding a three-dimensional object having an outer surface and an inner surface. Thus, after the formation of the at least one layer, the raw material can be introduced therein for processing. The build of the mold and object continues until the build operation of the three-dimensional object is completely completed.

The forming die is well suited for building thin-walled shell structures to reduce material and time consumption during the manufacturing process. The terms shell and former are used interchangeably herein unless otherwise specifically indicated.

Since the shaping die or shell mold determines the shape and size of the three-dimensional object to be fabricated, it is no longer necessary in the present invention to focus a fine energy beam, such as a laser or electron beam. In the absence of a powder bed around the shell and the feedstock, other types of energy sources can be used to simultaneously "macroscopically" treat the feedstock over a larger area and with increased layer thickness, so as not to affect dimensional resolution and surface quality. In other words, the dimensional accuracy and surface quality of the object produced in the shell mold is essentially dependent on the process capability and quality of the shell mold build, allowing the raw materials to be melted, sintered, solidified or hardened in a larger volume. Thus, the superiority of this method in terms of production efficiency and capacity is evident for additive manufacturing of larger and certain less readily fabricated parts (e.g., composites).

After the three-dimensional object is built, the shell may be removed in a subsequent process. In some cases, the shell may be bonded together with the raw materials therein to become a surface portion of a unified three-dimensional object. For some applications, this approach provides an alternative to building composite structures of different materials within a three-dimensional object, which is advantageous for achieving specific properties and reducing costs.

Referring to the drawings, wherein depicted parts are not necessarily drawn to scale or shown in full, wherein like elements are designated by like reference numerals throughout the several views and figures, the drawings illustrate an additive manufacturing method and an exemplary manufacturing system configured according to principles of the present invention.

Embodiments of the invention are discussed with reference to the figures. Those skilled in the art will understand that the detailed description herein with respect to these figures is for explanatory purposes and that other embodiments within the scope of the invention may be considered desirable. By way of example and not limitation, those skilled in the art will appreciate from the disclosure of the present invention that many alternative and suitable ways of performing any of the functions described herein, as well as other functions beyond those specifically described herein, may be required for a particular application. Various modifications and embodiments are possible within the scope of the invention, which is defined by the claims.

It is to be further understood that this invention is not limited to the particular methodology, materials, uses, and applications described herein as these may vary. Further, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It should be noted that, as used herein and in the claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "an element" is a reference to one or more elements and includes equivalents thereof known to those skilled in the art. All conjunctions used are to be understood as being included as much as possible. Thus, the word "or" should be understood to have a definition of logical "or" rather than a definition of logical "exclusive or" unless the context clearly dictates otherwise. Structures described herein are also to be understood as including functional equivalents of such structures. Language that describes the approximation should be understood as such, unless the context clearly dictates otherwise.

References to "one embodiment", "an example embodiment", and the like, may mean that one or more embodiments of the invention so described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic.

Fig. 1 shows an exemplary process flow diagram, which process flow may be further exemplified by additive manufacturing system 100 of fig. 2 a-2 d, which are also exemplary to this patent. In step 201, a user designs a mold 10 according to a three-dimensional object to be manufactured using computer aided design software, and generates a computer aided design model describing the geometric dimensions of the mold using a selected file format. The forming die 10 is preferably designed to have a thin-walled shell structure to minimize consumption and operation time of the forming die manufacturing material 20 during its construction. The design of the mold 10 and the selection of the mold material 20 should take into account the processing conditions and ensure that the mold 10 can withstand the processing conditions used to manufacture the feedstock 51 of the three-dimensional object and the conditions under which the three-dimensional object is manufactured.

The cavity in the forming die or shell 10 functions as a forming tool in forming at least a portion of a three-dimensional object, so the forming die cavity 18 is also referred to herein as a mold cavity 18.

Step 202 relates to generating a computer file using a software program by sequentially cutting a computer-aided design model of a formation mold design into a set of cross-sectional geometries and using the data, process parameters, and control specifications to control the additive manufacturing system 100 to perform operations for building the formation mold 10 and the three-dimensional object therein.

Depending on the process of constructing the molding die 10, the molding die manufacturing material 20 is generally formulated into a paste or slurry material using ceramic powder, metal powder, mineral material powder or other non-metallic material powder together with an inorganic or organic binder for use in a material Extrusion (Extrusion) or injection (spinning) process. Figure 2a illustrates an extruder apparatus 31 used in some embodiments to provide the mold-making material 20 and shape the mold 10. In various embodiments, extrusion may also be used for slurries with sufficient solids incorporation and viscosity. The low-viscosity slurry can be subjected to jet printing forming by using a spray head under appropriate liquid pressure. In some applications, material extrusion and injection methods may also be used to construct the mold 10 from a polymer melt and a resin.

In certain embodiments employing Energy-Directed Energy Deposition (Directed Energy Deposition), including laser, electron beam, and arc melting, a metallic forming die 10 (e.g., a shell die) may be constructed using a powdered or filamentary metallic material. In constructing the at least partial shell from a suitable alloy material, the shell material may be combined (e.g., melted or sintered) with the metal feedstock 51 in the die cavity 18 to form a metal workpiece having a composite structural composition change. When excellent surface properties are desired, such as where a metal workpiece is to be used for wear or corrosion resistance, high performance, high cost alloys can be used to construct the shell mold to provide the desired properties on at least a portion of the surface of the metal workpiece. However, another low cost alloy feedstock with compensating properties may be used to fill the mold cavity to build a composite structure of different alloys. These embodiments are particularly useful for reducing cost and improving performance when manufacturing medium and large workpieces.

In some applications, metal foil, textile, paper, or plastic film may be used in a sheet lamination (sheet lamination) process to construct the mold 10.

At step 203, a software program is used to run the computer executable file on the computer 5 (or the controller 5, the same below), and the computer 5 may be integrated into the system or a stand-alone or network device may be connected to the system to start the building operation of the forming die 10. The first layer 11 of the forming die 10 is built on a solid substrate, such as a build plate 41. The build plate 41 is mounted to the Z-axis translation mechanism 40 and may be made of metal or ceramic material for additive manufacturing of metal parts at high temperatures. In some embodiments, the mold 10 separates the build plate 41 from a first layer 81 of the built three-dimensional object or workpiece. In other embodiments, particularly when arc heating or electron beam heating is used to process metal feedstock 51 to produce a metal workpiece, the metal workpiece is required to conduct an electrical current to build plate 41, so that at least a portion of the metal workpiece is built on or in contact with metal build plate 41 unless otherwise connected to pass an electrical current.

In some embodiments, the built-up mold 10 may need to be heated or cured to harden it before it is used. The application of some type of energy or adjustment of process conditions may have a beneficial effect on the hardening of the mold 10. During the manufacture of metal workpieces at high temperatures, the heat dissipated from the very hot workpiece may be sufficient to harden the forming die 10.

When the mold 10 is built to the predetermined number of layers, the molding process is paused and the step 204 is initiated. The feeder 60 delivers the desired material 50 to the mold cavity 18. In some embodiments, the feeder moves along a prescribed trajectory in the X and Y directions within the cavity 18 under the control of the computer 5 to deliver the material 50 quantitatively at a prescribed location. Excess material 50, if it falls outside of the cavity 18, is collected. The embodiment shown in fig. 2b shows that the build plate 41 allows excess material 50 to be collected by scattering it down through the pores of the build plate 41. In some embodiments, collection of stray material may be more efficient with the aid of vibration of build plate 41 and vacuum collection. In addition to vacuum collection, other methods such as magnetic collection and sweeping may be used to collect the scattered material, as appropriate.

Before the material 51 in the cavity is processed, it is necessary to compact the material in the cavity 18 to increase its density. Some embodiments utilize mechanical compaction methods such as, but not limited to, vibration, shaking, roller compaction, mechanical compaction, and the like.

The selected types of feedstock 50 include: metals, plastics, ceramics, other inorganic materials, and composites. The feedstock may comprise a single or multiple component parts or ingredients, including a powder material, a filamentary material, a fibrous material, a sheet material, a liquid material, or a combination thereof. Suitable materials include, but are not limited to: powders, binders, additives, short fibers, long fibers, fiber bundles, woven fabrics, knitted fabrics, nonwoven fiber yarns (cloths), nonwoven fiber mats, Preform type (Preform), mesh materials, and the like.

In step 205, various embodiments process the feedstock 51 within the cavity 18 using a single or multiple energy sources to melt, sinter, harden, bond, densify, or solidify the feedstock to form at least a portion of a three-dimensional object. In various embodiments, there are a variety of options for the treatment process, including, without limitation: electromagnetic induction heating, electric arc heating, resistance heating, laser heating, electron beam heating, plasma arc heating, fuel combustion heating, torch heating, ultraviolet irradiation, remote fiber external radiation heating, microwave heating, radio frequency radiation heating, pressure processing, air pressure treatment, and ultrasonic welding. The purpose of the machining process is to allow the manufactured object or workpiece to meet the design specifications and to achieve the desired microstructure (grain size, physical morphology, composition, constituent phases, porosity, layer-to-layer bonding, inclusions, etc.) and properties (strength, hardness, ductility, toughness, density, etc.).

For additive manufacturing of metal workpieces at high temperatures, some protective atmosphere is often required to minimize the oxygen content in the ambient environment to avoid oxidation of the metal powder. Some embodiments utilize argon, nitrogen or carbon dioxide, while others use vacuum or a reducing gas containing hydrogen or carbon monoxide.

In addition to applying energy in processing the feedstock 51, some embodiments utilize chemical reactions or changes in physical state, such as exothermic reactions, Self-propagating reactions (Self-propagating reactions), cross-linking curing, chemical bonding, and solidification, to cure, harden, densify, join, sinter, or fuse the feedstock 51.

After the processing of the feedstock 51 within the mold cavity 18, at least one layer of a three-dimensional object or workpiece (e.g., the first layer 81) is completed. Before the object or workpiece is completely completed, steps 203, 204 and 205 are repeated to continue the build process. After this process is complete, the completed object or workpiece is subjected to subsequent processing to remove the forming or shell mold 10 and to the following processing steps such as, but not limited to: cutting, polishing, sand blasting, heat treatment, machining and the like, thereby meeting the production specification and quality requirements.

In the foregoing detailed description, reference has been made to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, and certain variants thereof, have been described in sufficient detail to enable those skilled in the art to utilize the invention. It is to be understood that other suitable embodiments may be utilized and logical changes may be made without departing from the spirit or scope of the present invention. The description may omit certain information known to those of skill in the art. Therefore, the foregoing detailed description is not intended to be limited to the language and scope herein, but on the contrary, it is intended to cover alternatives, modifications, and equivalents, which may be reasonably included within the spirit and scope of the appended claims.