The invention relates to the field of additive manufacturing technology, and in particular to a composite forming system and method combining additive manufacturing and forging.
Additive manufacturing technology is an emerging technology for material processing that is rapidly developing. At present, the mainstream additive manufacturing usually achieves metallurgical bonding of metal materials through the “melting-solidification” method, which is characterized by using a high-energy beam such as a laser beam, an electron beam or an arc beam as a heat source to melt the synchronously fed metal material, such as metal powder, metal wire, and so on, which are stacked in layers, whereby parts are manufactured by surfacing, and the internal microstructure of the obtained parts is a solidified structure.
Compared with the conventional forged structure, the solidified structure obtained by the above-mentioned “melting-solidification” method produces crystals that are very coarse with obvious directionality, therefore in a general sense, it is difficult to achieve comprehensive performance comparable to that of a forged material. In order to improve the mechanical properties of the obtained parts and reduce internal defects, a method of combining the molten deposition additive with thermomechanical processing has been gradually developed, that is, material deposition and metallurgical bonding are achieved by melting-solidification, thereafter rolling, shock processing and other treatments are used to refine the grains and improve internal quality.
Although the method of melting combined with forging can improve the internal quality as well as enhance performance to some extent, in this composite processing method, due to the high complexity of the process and the equipment, as well as due to the rapid solidification and cooling rate, the forging condition which includes the temperature and other parameters cannot be effectively controlled, thus affecting the scope of application of the materials as well as the effect of forging.
Therefore, new technologies are needed to solve at least one of the above problems.
The objective of the present invention is to provide a composite forming system combining additive manufacturing and forging as well as its methods.
In one aspect, embodiments of the present invention relate to an additive manufacturing system comprising a material conveyor, an energy source, and a micro-forging device. The material conveyor is configured to convey material. The energy source is configured to direct an energy beam toward the material, the energy beam fuses at least a portion of the material to form a solidified portion. The micro-forging device is movable along with the material conveyor for forging the solidified portion, wherein the micro-forging device comprises a first forging hammer and a second forging hammer, the first forging hammer is configured to impact the solidified portion to generate a first deformation, and the second forging hammer is configured to impact the solidified portion to generate a second deformation greater than the first deformation.
In another aspect, embodiments of the present invention relate to an additive manufacturing method. The method comprises: feeding a material via a material conveyor to a platen; directing an energy beam towards the material to fuse at least a portion of the material to form a solidified portion; and forging the solidified portion by: moving a micro-forging device comprising a first forging hammer and a second forging hammer, along with the material conveyor; impacting the solidified portion with the first forging hammer to generate a first deformation; and impacting the solidified portion with the second forging hammer to generate a second deformation greater than the first deformation.
To read the following detailed description with reference to the accompanying drawings can help understand the features, aspects and advantages of the present invention, where:
“Comprise”, “include”, “have”, and similar terms used in the present application are meant to encompass the items listed thereafter and equivalents thereof as well as other additional items. Approximating language in the present application is used to modify a quantity, indicating that the present invention is not limited to the specific quantity, and may include modified parts that are close to the quantity, acceptable, and do not lead to change of related basic functions.
In the specifications and claims, unless otherwise clearly indicated, no limitation is imposed on singularity and plurality of all items. Unless otherwise clearly indicated, the terms “OR”, “or” do not mean exclusiveness, but mean at least one of the mentioned item (such as ingredients), and include a situation where a combination of the mentioned exists.
“Some embodiments” and the like mentioned in the present application specification represent that specific elements (such as a characteristic, structure, and/or feature) related to the present invention are included in at least one embodiment described in the specification, and may or may not appear in another embodiment. In addition, it should be understood that the invention elements can be combined in any manner.
Embodiments of the present invention relate to an additive manufacturing system and its methods, comprising an additive manufacturing device for forming an object layer-by-layer by additive manufacturing techniques, and a micro forging device used for real-time micro-forging by matching the object being formed by the additive manufacturing device synchronously layer-by-layer. Wherein the additive manufacturing device may comprise: a platen provided to support the object being formed, a material conveyor configured to feed material onto the platen or the object being formed, and an energy source configured to provide an energy beam, which directs the energy beam toward the material when it is being fed and melts it to form a solidified portion. Specifically, the real-time micro-forging device is movable synchronously with the material conveyor for forging the solidified portion after the material conveyor. The real-time micro-forging device comprises a first forging hammer and a second forging hammer, the first forging hammer being configured to pre-forge the solidified portion and generate a first deformation, the second forging hammer being configured to forge the pre-forged solidified portion and generate a second deformation greater than the first deformation
The energy source 116 can be any device or equipment capable of providing an energy beam suitable for additive manufacturing. Specific examples of the energy beam include, but are not limited to, a laser beam, an electron beam, and an arc beam. The material 115 is typically delivered in the form of a powder or wire (e.g., metal powder, wire, etc.). The material conveyor 114 may comprise a powder feed nozzle for conveying powder material, or a wire feeding device for conveying the wire. In some embodiments, the material conveyor 114 comprises a powder feed nozzle or wire feed device that is coaxial with the energy beam. For example, in the embodiment illustrated in
In some embodiments, the real-time micro-forging device 140 comprises two or more forging hammers, the hammers are able to control parameters such as respective forging force and hammering frequency independently of each other. In the embodiment shown in
In some embodiments, the deformations generated by each forging hammer can be controlled, and the total deformation generated by the entire real-time micro-forging device 140 can also be controlled, for example, the total deformation can be controlled to be no greater than a range of 50%. In some specific embodiments, the first deformation can be controlled within the range of 5% to 15%, and the second deformation can be controlled within the range of 15% to 35%.
In some embodiments, the real-time micro-forging device 140 may further comprise more forging hammers, for example, further comprising a third forging hammer (not shown) configured to perform further forging after the solidified portion being forged by the second forging hammer 142, and generate a third deformation greater than the second deformation.
In some embodiments, the real-time micro-forging device 140 is movable relative to the additive manufacturing device 110, thereby adjusting its distance from the center of the molten pool (the location at which the material is melted). For example, in some specific embodiments, the real-time micro-forging device 140 is movable relative to the material conveyor 114 between a hot forging position and a cold forging position, wherein, when the real-time micro-forging device 140 is located at the hot forging position, the first forging hammer 141 performs pre-forging at a position of 2 mm to about 9 mm from a molten pool, and when the real-time micro-forging device 140 is located at the cold forging position, the first forging hammer 141 performs pre-forging at a position greater than 9 mm from the molten pool. In some embodiments, when the real-time micro-forging device 140 is located at the cold forging position, the real-time forging (including the pre-forging performed by the first forging hammer 141 and the forging performed by the second forging hammer 142) is performed at a temperature ranging from 30% to 50% of the melting point of the material. When the real-time micro-forging device 140 is located at the hot forging position, the real-time forging is performed at a temperature ranging from 60% to 80% of the melting point of the material.
The composite forming system 100 may comprise control devices (not shown) to realize control of the additive manufacturing device 110, the real-time micro-forging device 140, and other devices in the system, including but not limited to: control of the relative position of the real-time micro-forging device 140, control of the motion parameters of multiple forging hammers.
In some specific embodiments, the control device can adaptively adjust the distance to the center of the molten pool based on the energy beam used by the additive manufacturing device 110. When the energy beam is an arc beam, the real-time micro-forging device 140 is located at the cold forging position, the first forging hammer head 141 performs pre-forging at a position greater than 9 mm from the molten pool, the real-time forging (including the forging performed by the first forging hammer 141 and the forging performed by the second forging hammer 142) is performed at a temperature ranging from 30% to 50% of the melting point of the material. When the energy beam is a laser beam or an electron beam, the first forging hammer 141 performs pre-forging at a position 2 mm to 9 mm from the molten pool, the real-time micro-forging device 140 is located at the hot forging position, the real-time forging is performed at a temperature ranging from 60% to 80% of the melting point of the material. For example, for a nickel-based alloy having a melting point of about 1,600° C., the cold forging is generally performed at a temperature ranging from 480° C. to 800° C., and the hot forging is generally performed at a temperature ranging from 960° C. to 1,280° C.
The composite forming system 100 may further comprise a real-time polishing device 160 that can be moved synchronously with the real-time micro-forging device 140 by following the real-time micro-forging device 140, to perform real-time polishing of the solidified portion after being forged by the real-time micro-forging device 140 and eliminate unevenness resulting from forging, thereby facilitating material stacking and additive manufacturing for the subsequent layer. The polishing device may comprise a micro-grinding wheel or a micro-milling cutter to smooth the forged portion. In some specific embodiments, the additive manufacturing device 110, the real-time micro-forging device 140, and the real-time polishing device 160 are sequentially arranged, such that the materials melted at the molten pool may be forged by a plurality of hammers arranged in sequence after solidification, to repeat the steps of melting-solidification-multiple forging-polishing after polishing to obtain the next layer.
In some embodiments, the additive manufacturing device 110, the real-time micro-forging device 140, and the real-time polishing device 160 are connected by a certain connecting mechanism 180. The arrangement of the connecting mechanism 180 enables relative motion and synergy between the devices 110, 140, 160. The connecting mechanism comprises, but is not limited to, a connecting rod, a bracket, a sliding device, and so on.
The composite forming system 100 is widely applicable to various materials for additive manufacturing, and is particularly suitable for high-temperature alloy materials such as nickel-based and cobalt-based alloys, whose mechanical properties are not substantially degraded in a use environment below 650° C.
The hammer assembly 244 can be used as any of the forging hammers in the composite forming system 100 shown in
Since the real-time micro-forging device comprises two or more forging hammers, each of the layers formed by the additive manufacturing can be hammered by the hammers several times, which can solve the problem of the previous layer remelting due to the heat input from the forming process of the subsequent layer to a certain extent, which may occur during the layer-by-layer stack forming process.
While the present invention has been described with reference to specific embodiments thereof, it will be understood by those skilled in the art that many modifications and variations can be made thereto. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and variations insofar as they are within the true spirit and scope of the invention.
Number | Date | Country | Kind |
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201711013952.7 | Oct 2017 | CN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/US2018/057749 | 10/26/2018 | WO | 00 |