Micro-nozzle assembly, multi-powder feeding device and method

Abstract

This invention discloses a micro-nozzle assembly, a multi-powder feeding device, and a method, aiming to solve the problems of low efficiency and unstable process in multi-material additive manufacturing in the prior art. The multi-powder feeding device includes a fixing frame and multiple micro-nozzle assemblies mounted thereon. The core of this micro-nozzle assembly lies in the fact that a portion of its body is formed as a common elastic substrate with slits, thereby defining multiple independently bending and vibrating vibrating corridors. By independently driving each vibrating corridor through multiple electro-actuated elements, the on-demand feeding of various powders can be precisely controlled, eliminating the need for the traditional "powder suction-filling" process and significantly improving the efficiency and stability of multi-material additive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, specifically to an integrated micro-nozzle assembly for laser selective melting processes, a powder feeding device capable of accurately conveying multiple powders, and a corresponding powder feeding method. Background Technology

[0002] Selective laser melting (SLM), a cutting-edge metal additive manufacturing technology, works by layering metal powder onto a substrate using a powder-laying mechanism, and then selectively melting the powder using a high-energy laser beam based on the 3D model slice data of the part, thus stacking the powder layer by layer to obtain complex metal parts.

[0003] However, traditional SLM technology is mainly limited to the manufacture of single materials, making it difficult to meet the manufacturing needs of complex heterogeneous components (such as functionally graded materials) in fields such as aerospace and biomedicine, where material properties are spatially distributed as needed. To address this, multi-material / multi-powder SLM technology has emerged, the key to which lies in the ability to precisely distribute different types of powders at any location during the forming process.

[0004] Currently, the mainstream technology for multi-material powder feeding typically employs a "first lay, then remove, then fill, then lay again" process. This process first evenly lays a first type of powder on the substrate, then uses a vacuum nozzle or similar device to remove the powder from the area where the material to be replaced, forming a groove. A second type of powder is then filled into the groove and leveled. This method has significant drawbacks: First, each additional material requires repeating the "powder suction" and "powder filling" operations. As the number of material types increases, the number of process steps grows exponentially, resulting in extremely low forming efficiency. Second, the powder suction and filling processes are prone to cross-contamination, affecting the metallurgical quality and performance stability of the parts. Finally, the equipment structure is complex and difficult to control.

[0005] Therefore, there is an urgent need in this field for a new, efficient, and stable multi-powder feeding technology to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned defects of the prior art and to provide a novel and precisely controlled micro-nozzle assembly. Based on this, it provides an efficient and stable multi-powder feeding device and a corresponding powder feeding method to systematically solve the powder feeding problem in multi-material additive manufacturing.

[0007] To address the aforementioned technical problems, the present invention first provides a micro-nozzle assembly, comprising:

[0008] The component body has a portion formed as a common elastic substrate with a set of parallel slits, each slit opening at the lower edge of the elastic substrate, thereby defining multiple vibrating corridors that can independently undergo bending vibration. Another portion of the component body forms a common fixing plate, which, together with the multiple vibrating corridors, defines a common powder channel and multiple discharge ports.

[0009] Multiple electrically actuated elements are fixed to multiple vibrating corridors. When receiving an electrical signal, the electrically actuated elements drive the vibrating corridors to generate high-frequency bending vibrations, thereby selectively promoting or preventing the conveying of powder in the common powder channel through the discharge port corresponding to the vibrating corridor.

[0010] The present invention further provides a multi-powder feeding device, comprising:

[0011] A fixed frame that can move above the molding substrate along the powder spreading direction;

[0012] At least two aforementioned micro-nozzle assemblies are arranged in an array and mounted on the fixture, and the common powder channel of the different micro-nozzle assemblies respectively accommodates different types of powder.

[0013] Preferably, at least two micro-nozzle assemblies are arranged at intervals along the powder spreading direction, and the arrangement direction of multiple vibrating fingers in each micro-nozzle assembly is perpendicular to the powder spreading direction.

[0014] The present invention also provides a method for feeding multiple powders, using the aforementioned device for powder feeding, the method comprising the following steps:

[0015] (a) According to the different types of powder required for the workpiece to be printed, the different types of powder are respectively filled into the common powder channel of the different micro-nozzle assemblies of the device;

[0016] (b) Control the fixing frame to move above the forming substrate along the powder spreading direction;

[0017] (c) Based on the material distribution data of the current layer of the workpiece to be printed, control the electro-actuated elements on each vibrating finger in each micro-nozzle assembly in real time and independently to selectively deliver one or more powders to a predetermined position on the forming substrate.

[0018] (d) Selectively laser melt the powder layer that has been delivered to the forming substrate according to the shape of the current layer of the workpiece to be printed;

[0019] (e) Reduce the thickness of the forming substrate by one layer, and then repeat steps (b) to (d) until the workpiece is formed.

[0020] Preferably, between steps (a) and (b), a calibration step is also included: establishing a correspondence between the electrical signal parameters of the electro-actuated element on each vibrating corridor within the micro-nozzle assembly and the powder output flow rate at the outlet corresponding to that vibrating corridor.

[0021] Compared with the prior art, the micro-nozzle assembly, multi-powder feeding device and method provided by the present invention have the following significant advantages:

[0022] 1. This invention employs a direct-write pure additive manufacturing method, directly "printing" powder layers composed of multiple powders at predetermined locations using a parallel-operating, independently operable, high-speed vibrating aisle array. This completely eliminates the time-consuming vacuum adsorption and secondary filling steps, reducing the preparation time of multi-material powder beds by several orders of magnitude. In particular, the efficiency advantage of this invention becomes increasingly significant as the number of required materials increases, fundamentally solving the technical bottleneck of exponential efficiency decline in existing technologies due to the increase in the number of material types.

[0023] 2. The core of this invention lies in using an electrically actuated element to drive a vibrating corridor to generate high-frequency bending vibration. This vibration can instantly and effectively destroy the static friction and cohesive force between powder particles, achieving precise control over the on / off state of trace amounts of powder. This non-contact, energy field-based direct driving method, compared to existing technologies such as vacuum adsorption and mechanical filling, completely avoids problems such as powder cross-contamination, uneven local compaction density, and incomplete filling of grooves caused by negative pressure fluctuations or mechanical disturbances. This ensures the compositional purity and structural uniformity of each powder bed layer, providing a solid and reliable process guarantee for obtaining high-quality, high-performance final parts.

[0024] 3. The most innovative aspect of this invention is the integrated micro-nozzle assembly, which forms the entire vibrating finger array by machining slits on a common elastic substrate. This integrated design ensures extremely high consistency in the mechanical properties of each channel, which is crucial for achieving uniform powder feeding. Compared to assembling multiple independent nozzles, this design significantly simplifies the manufacturing and assembly process, reduces costs, and improves reliability. This modular, high-precision design provides unprecedented capabilities for manufacturing functionally graded materials and heterogeneous structural components with complex geometries and composition-on-demand design, representing a novel solution for additive manufacturing of high-performance, complex components. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the micro-nozzle according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the micro-nozzle assembly according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of an electro-actuating element attached to an elastic substrate according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the structure of the multi-powder feeding device according to an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 10, Nozzle body; 11, Powder channel; 12, Discharge port; 13, Vibrating plate; 131, Mounting plate; 14, Fixing plate; 20, Electro-actuating element; 30, Component body; 31, Elastic substrate; 311, Slit; 312, Vibrating finger; 32, Common fixing plate; 33, Common powder channel; 40, Fixing frame; 50, Forming substrate. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention more apparent and understandable, specific embodiments of the invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit the scope of protection of the invention.

[0031] This invention provides a micro-nozzle, a micro-nozzle assembly, a multi-powder feeding device, and a method for powder feeding in additive manufacturing.

[0032] This invention provides a micro-nozzle assembly, a multi-powder feeding device, and a method. To better understand the core of this invention, we can first understand the structure of a micro-nozzle, which constitutes its basic unit.

[0033] Please see Figure 1 This demonstrates the structure of a basic micro-nozzle. The micro-nozzle mainly comprises a nozzle body 10 and an electro-actuating element 20. The nozzle body 10 is the main structure for receiving and guiding powder, defining a powder channel 11 internally and forming an outlet 12 at its lower end. A portion of the nozzle body 10 is formed as a vibrating plate 13, which constitutes one side wall of the powder channel 11; another portion of the nozzle body 10 forms a fixed plate 14, serving as the other side wall of the powder channel 11. The electro-actuating element 20 is fixed to the outer surface of the vibrating plate 13, selectively controlling the conveying of powder within the powder channel 11 through the outlet 12 by causing the vibrating plate 13 to bend and vibrate.

[0034] When the external control system applies an electrical signal to the electro-actuated element 20, it generates mechanical deformation, thereby driving the rigidly connected vibrating plate 13 to produce high-frequency bending vibration. This bending vibration can effectively overcome the static friction, van der Waals force, and possible bridging effect between powder particles near the discharge port 12, allowing the powder to flow out smoothly. When the electrical signal stops, the vibrating plate 13 stops vibrating, and the powder, due to its own physical characteristics such as its angle of repose, will quickly stop flowing at the discharge port 12. In this way, precise and selective control of the powder flow can be achieved.

[0035] As a preferred option, such as Figure 1 As shown, the vibrating plate 13 forms a cantilever beam structure with its upper end as the fixed end and its lower end near the discharge port 12 as the free end. This structure can amplify the small deformation generated by the electric actuator 20 into significant displacement and amplitude at the free end, thereby achieving efficient energy transfer and powder driving.

[0036] In terms of specific material selection, the electric actuator 20 is preferably a piezoelectric ceramic sheet, due to its advantages such as fast response speed (down to the microsecond level), high displacement control accuracy, simple structure, and good reliability. Of course, other types of electric actuators can also be used, such as electromagnetic, electrostatic, or thermally driven actuators.

[0037] In addition, such as Figure 1 and Figure 2 As shown, a mounting plate 131 can also be provided on the upper part of the vibrating plate 13 for mounting and fixing the upper end of the vibrating plate 13.

[0038] The core of this invention lies in a preferred embodiment that highly integrates the aforementioned basic units: a micro-nozzle assembly.

[0039] Please see Figure 2 and Figure 3 This demonstrates the micro-nozzle assembly of the present invention. Compared to physically splicing together multiple independent individual micro-nozzles, this integrated design offers higher precision, better consistency, and superior manufacturability.

[0040] The micro-nozzle assembly includes a component body 30 and multiple electrically actuated elements 20. The component body 30 ingeniously integrates the structures of multiple micro-nozzles into one unit. Specifically, a portion of the component body 30 is formed as a common elastic substrate 31. This elastic substrate 31 is typically made of a material with good elastic recovery properties, such as spring steel.

[0041] Please refer to this document. Figure 3The elastic substrate 31 has a set of parallel slits 311, each slit 311 extending upwards from the lower edge (free end) of the elastic substrate 31 by a certain distance, thereby dividing the lower region of the elastic substrate 31 into multiple independent, elongated vibrating corridors 312. Each vibrating corridor 312 is functionally equivalent to the vibrating plate 13 of the aforementioned single micro-nozzle, and since its upper part is still connected to the substrate body, it naturally forms a cantilever beam structure.

[0042] Another part of the component body 30 is formed as a common fixing plate 32. This common fixing plate 32 is combined with the elastic substrate 31 such that the front surface of the common fixing plate 32 faces the rear surface of the plurality of vibrating corridors 312, jointly defining a common powder channel 33 and a plurality of discharge ports 12 corresponding to each vibrating corridor 312. A plurality of electro-actuating elements 20, such as piezoelectric ceramic sheets, are fixed one-to-one to the outer surface of each vibrating corridor 312.

[0043] The advantages of this integrated design are obvious: all the vibrating corridors 312 can be formed on the same elastic substrate 31 through a single precision machining process (such as laser cutting, etching, etc.), ensuring extremely high consistency and positional accuracy between the powder channels corresponding to each vibrating corridor 312. At the same time, it integrates multiple parts that originally required multiple assemblies into a few components, greatly simplifying the assembly process and improving production efficiency and equipment reliability.

[0044] To better understand the structural hierarchy of this invention, it should be noted that the micro-nozzle, its powder channel 11, and the fixing plate 14 constitute the most basic functional unit of this invention. The micro-nozzle assembly described in this embodiment is a preferred, highly integrated implementation of this basic functional unit. Specifically, in the micro-nozzle assembly, multiple basic functional units are integrated into one unit. Therefore, the common fixing plate 32 in the micro-nozzle assembly functionally corresponds to an assembly of multiple fixing plates 14, while the common powder channel 33 is a connected channel that supplies material to the discharge ports 12 corresponding to multiple vibrating finger corridors 312, and its function corresponds to an assembly of multiple independent powder channels 11. By assigning independent reference numerals to these physically different components, the scope of protection and structural hierarchy of this invention are clearly defined.

[0045] Please see Figure 4 The diagram illustrates the system configuration and operation of the multi-powder feeding device of the present invention. The device includes a mounting frame 40 movable above a forming substrate 50, and at least two (four in the example) of the aforementioned micro-nozzle assemblies mounted on the mounting frame 40.

[0046] These micro-nozzle components are along the powder spreading direction ( Figure 4 The micro-nozzle components are arranged at intervals in the X direction. Each micro-nozzle assembly has a common powder channel 33 that can accommodate different types of powder, such as powder A, powder B, powder C and powder D in the figure.

[0047] The working method of this invention is as follows:

[0048] First, before printing begins, different types of powder (powder A, B, C, and D) are filled into the common powder channel 33 of different micro-nozzle assemblies on the fixture 40, according to the material type required for the workpiece to be printed. Preferably, a calibration step can be performed before the actual printing: different electrical signal parameters (such as voltage, frequency, duty cycle, etc.) are applied to the electro-actuated element 20 on each vibrating finger 312 by the control system, and the corresponding powder output flow rate is measured, thereby establishing an accurate "signal-flow" database to ensure accurate powder feeding in the future.

[0049] During printing, the control system drives the fixing frame 40 to move at a constant speed above the forming substrate 50 along the powder spreading direction X. Simultaneously, based on the material distribution data of the current layer of the workpiece to be printed, the control system sends or stops electrical signals to the electro-actuated elements 20 on specific vibrating corridors 312 inside specific micro-nozzle assemblies in real time and independently. When an electro-actuated element 20 receives a signal, its corresponding vibrating corridor 312 bends and vibrates, and the powder in the powder channel corresponding to that vibrating corridor 312 is conveyed out; when the signal stops, the powder dispensing also stops. Through this "pixel-level" independent control, a powder layer composed of multiple powders precisely distributed according to a predetermined pattern can be "printed" on the substrate. Figure 4 As shown, the device can precisely lay out a complex ring-shaped and block-shaped structure composed of powders A, B, C, and D.

[0050] After the multi-material powder layer is laid, the laser system of the SLM equipment will selectively laser melt the powder layer according to the geometry of the part at that level.

[0051] After melting is complete, the forming substrate is lowered by one layer of thickness, and then the fixing frame 40 moves again to lay down the next layer of multi-material powder. This cycle is repeated until the entire three-dimensional workpiece is formed.

Claims

1. A multi-powder powder feeder, characterized by, The device comprises a fixed frame (40) movable above a forming substrate (50) along a powder spreading direction, and at least two micro-nozzle assemblies arranged in an array and mounted on the fixed frame (40), wherein each micro-nozzle assembly comprises: a component body (30), a part of which is formed into a common elastic substrate (31) provided with a set of parallel slits (311) each opening at a lower edge of the elastic substrate (31) to define a plurality of vibration fingers (312) capable of independent bending vibration, and another part of which is formed into a common fixed plate (32) together with the plurality of vibration fingers (312) to define a common powder channel (33) and a plurality of discharge ports (12); a plurality of electric actuating elements (20) respectively fixed on the plurality of vibration fingers (312), the electric actuating elements (20) being configured to drive the vibration finger (312) fixed thereon to generate high-frequency bending vibration upon receiving an electric signal, so as to selectively facilitate or prevent the powder in the common powder channel (33) to be transported through the discharge port (12) corresponding to the vibration finger (312). The common powder channels (33) of different micro-nozzle assemblies respectively contain different types of powder.

2. The apparatus of claim 1, wherein, The at least two micro-nozzle assemblies are arranged in an array along the powder spreading direction, and the plurality of vibration fingers (312) in each micro-nozzle assembly are arranged in a direction perpendicular to the powder spreading direction.

3. A multi-powder feed method, characterized by, The device of claim 1 or 2 is used for powder feeding, and the method comprises the following steps: (a) filling different types of powder into the common powder channels (33) of different micro-nozzle assemblies of the device according to the different types of powder required by the workpiece to be printed; (b) controlling the fixed frame (40) to move above the forming substrate (50) along the powder spreading direction; (c) controlling the electric actuating elements (20) on the vibration fingers (312) in each micro-nozzle assembly in real time and independently according to the material distribution data of the current level of the workpiece to be printed, so as to selectively transport one or more types of powder to a predetermined position of the forming substrate (50); (d) selectively laser melting the powder layer transported onto the forming substrate (50) according to the shape of the current level of the workpiece to be printed; (e) lowering the forming substrate (50) by a thickness of one level, and then repeating steps (b) to (d) until the workpiece is formed.

4. The method of claim 3, wherein, Between steps (a) and (b), a calibration step is further included, i.e. establishing a corresponding relationship between the electric signal parameter of the electric actuating element (20) on each vibration finger (312) in the micro-nozzle assembly and the powder output flow rate of the discharge port (12) corresponding to the vibration finger (312).

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