Apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminate composites

Abstract

The present invention aims to provide an apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials, belonging to the field of metal matrix composite additive manufacturing technology. It includes a current-assisted heat source and a substrate. The two ends of the substrate along its length are located within a groove. A metal foil is disposed on the substrate along its length. An electric push rod is disposed at the bottom of the groove along the length of the substrate, with its end connected to the substrate. The positive and negative electrodes of the current-assisted heat source are clamped at both ends of the metal foil and the substrate. An upper ultrasonic indenter vibrating axially and a lower ultrasonic indenter vibrating normally are respectively disposed at the top of the metal foil and the bottom of the substrate. The upper and lower ultrasonic indenters are in contact with the metal foil and the substrate, respectively. The width of the metal foil is smaller than the width of the upper ultrasonic indenter. This invention can be used for single-pass multi-layer rapid prototyping of high-strength metal laminated composite materials.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for metal matrix composites, and specifically relates to an apparatus and method for current-assisted bidirectional ultrasonic additive manufacturing of metal laminate composites. Background Technology

[0002] Since its inception, additive manufacturing technology has played an increasingly important role in the manufacturing sectors of various countries. Currently, common additive manufacturing technologies primarily utilize powder metallurgy, which uses electron beams, lasers, or plasma beams as heat sources to locally melt and deposit metal powder layer by layer. This method enables the rapid fabrication of various complex parts; however, it also has many limitations. For example, the introduction of high-energy beams can easily generate thermal stress within the workpiece, thus affecting bonding strength; the manufacture of complex parts requires special molds, significantly increasing equipment costs; and the powder preparation process is complex and time-consuming, impacting processing efficiency. Therefore, current additive manufacturing technology urgently needs innovation.

[0003] In recent years, the application of dissimilar metal composite materials has begun to attract attention. Titanium-aluminum dissimilar metal laminated composite materials can achieve the complementary advantages of the two metal materials, realize the lightweight of structural materials, and at the same time ensure the high specific strength and corrosion resistance of the materials. They have great application value in aerospace, ground weapons, rail transportation and other fields.

[0004] To overcome the shortcomings of traditional forming and manufacturing processes for metal laminated composites (such as explosive forming, rolling composite, and brazing), ultrasonic metal additive manufacturing (UAM) technology has emerged in recent years, providing a more effective and faster solution for the design and preparation of metal matrix composites. This forming technology requires no external energy input; under the influence of ultrasonic energy and static pressure, metal atoms at the interface diffuse to achieve solid-state physical metallurgical bonding, thereby realizing solid-state connection and forming between metal foils. However, this method is currently mainly suitable for metal materials with good plasticity and low hardness. For metal materials with higher hardness, consolidation is often achieved by preheating the base plate and increasing the consolidation pressure. However, this method causes a series of problems, such as excessively long preheating and cooling times, significant influence of external environmental conditions on the processing technology, local residual stress caused by large temperature differences, slight consolidation cracks due to increased pressure, and foil adhesion damage. Summary of the Invention

[0005] This invention addresses the problems of long preheating and cooling times, significant influence of external environmental conditions on the processing, and residual local stress caused by temperature changes in traditional ultrasonic additive manufacturing processes. It also addresses shortcomings such as complex processing steps during consolidation, poor bonding of formed samples, slight consolidation cracks, foil adhesion damage, and limited plasticizing ability for high-strength metal materials, making it difficult to rapidly form higher-strength and thicker metal laminates. This invention provides a device and method for manufacturing metal laminate composite materials using current-assisted bidirectional ultrasonic additive manufacturing. The invention utilizes two ultrasonic pressure heads working simultaneously to generate high-frequency ultrasonic vibrations in two directions, combined with the electro-softening and resistance-thermal softening effects of current-assisted preheating. This improves the plastic deformation of the metal foil, softening it and promoting bonding.

[0006] The present invention adopts the following technical solution:

[0007] An apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials includes a current-assisted heat source, a substrate, and a chute. The two ends of the substrate along its length are located in the chute. A metal foil is provided on the substrate along its length. An electric push rod is provided at the bottom of the chute along the length of the substrate. The end of the electric push rod is connected to the substrate. The positive and negative electrodes of the current-assisted heat source are clamped at the two ends of the metal foil and the substrate. An upper ultrasonic pressure head that vibrates axially and a lower ultrasonic pressure head that vibrates normally are respectively provided at the top of the metal foil and the bottom of the substrate. The upper and lower ultrasonic pressure heads are in contact with the metal foil and the substrate, respectively. The width of the metal foil is smaller than the width of the upper ultrasonic pressure head.

[0008] Furthermore, the current-assisted heat source is a hot-wire argon arc welding machine.

[0009] Furthermore, the metal foil is located at the center of the substrate.

[0010] Furthermore, the upper ultrasonic pressure head is located directly above the metal foil, and the lower ultrasonic pressure head is located directly below the substrate.

[0011] Furthermore, the electric linear actuator includes a controller, a motor, and a linear actuator. The controller is electrically connected to the motor, the output end of the motor is connected to the linear actuator, and the end of the linear actuator is connected to the base plate via a connecting block.

[0012] Furthermore, there are two electric push rods, located at the bottom of the slide grooves at both ends, and arranged symmetrically with respect to the axis of the substrate.

[0013] A method for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials includes the following steps:

[0014] The first step is to prepare the metal foil required for solidification, clean the surface oil with ultrasonic cleaner and dry it for later use, clean the oxide film of the substrate by mechanical polishing, and wipe it with acetone and alcohol. Then lay the metal foil on the substrate as required.

[0015] The second step involves clamping the positive and negative electrodes of the externally applied current-assisted heat source to both ends of the metal foil and the substrate, respectively, to form a closed circuit between the metal foil and the substrate for preheating.

[0016] In the third step, the lower ultrasonic pressure head located directly below the metal foil and the substrate, and the upper ultrasonic pressure head in contact with the metal foil, work simultaneously to generate ultrasonic vibrations along the normal and axial directions on the metal foil. At the same time, the substrate connected to the end of the push rod and the fixed metal foil slide along the groove under the drive of the push rod. Under the high-frequency vibration of the fixed upper and lower ultrasonic pressure heads, the metal foil consolidation work is completed.

[0017] Furthermore, the metal foil includes titanium foil and pure aluminum foil.

[0018] Furthermore, the upper ultrasonic indenter has an ultrasonic amplitude of 25~30μm and a consolidation pressure of 2.0~2.5KN, the lower ultrasonic indenter has an ultrasonic amplitude of 32~36μm and a substrate sliding speed of 20mm / s, a closed-loop current of 10~30A, and a preheating temperature of 160℃.

[0019] This invention clamps the positive and negative electrodes of an externally applied current-assisted heat source at both ends of a metal foil and a substrate, forming a closed loop between the metal foil and the substrate. This utilizes resistance heating to achieve an externally assisted heating effect. During the consolidation process, the pressure head of the ultrasonic vibration device located directly below the metal foil and substrate, and the pressure head in contact with the foil, work simultaneously. This generates ultrasonic vibrations along the normal direction and along the axial direction of the pressure head on the foil. Under the action of high-frequency ultrasonic vibration along the axial direction and static pressure, the upper pressure head causes the layers of the metal foil to undergo plastic deformation through mutual compression and friction, leading to the interdiffusion of metal atoms and the formation of interlayer metallurgical bonding. The lower pressure head, utilizing high-frequency ultrasonic vibration along the normal direction of the metal foil and the action of counter-pressure, generates heat through elastic vibration energy, causing the material to undergo intense plastic deformation in the normal direction. This promotes the infinite approach, bonding, and diffusion of metal atoms at the interlayer interfaces.

[0020] Simultaneously, the substrate connected to the end of the push rod and the fixed metal foil slide along the groove at a certain speed under the drive of the push rod. Under the high-frequency vibration of the fixed upper and lower pressure heads, the single-layer or multi-layer titanium-aluminum foil is solidified.

[0021] The beneficial effects of this invention are as follows:

[0022] 1. Conventional base plate heating methods have significant drawbacks. Heat is generated from the base plate and transferred to the solidification interface via thermal conduction. As the height and number of layers of the solidification material increase, the heat transfer path becomes increasingly longer. Furthermore, the poor thermal conductivity of titanium further hinders heat transfer to the interface, resulting in insufficient metal softening, minimal plastic deformation and atomic diffusion, making it difficult to form an effective bond. In contrast, the device of this invention, with its current-assisted heating, exhibits a more pronounced heating effect as the current increases. At currents of 25A to 30A, it can achieve temperature rises of 135°C to 165°C within a short time, approaching or exceeding the optimal base plate preheating temperature of 160°C. This demonstrates that the current-assisted heating method has a significant efficiency advantage over the base plate preheating method.

[0023] 2. In the usual consolidation process, the processing steps are relatively complex, the plasticizing ability of high-strength metal materials is generally limited, and the bonding effect of the formed samples is poor. If the consolidation pressure is increased indiscriminately, slight consolidation cracks and foil adhesion damage may occur, making it difficult to quickly form metal laminates with higher strength and thickness. This device uses two ultrasonic consolidation devices with different powers. The two ultrasonic pressure heads simultaneously provide ultrasonic high-frequency vibrations in two different directions (axial and normal) to the metal foil. This not only effectively enhances the plastic deformation ability of the metal foil, but the ultrasonic system in the normal direction is also conducive to promoting the bonding between the two metal foils. Moreover, it can be used for single-pass multi-layer rapid forming of high-strength metal laminate composite materials.

[0024] 3. By using the apparatus and method of the present invention to prepare metal laminated composite materials, no gas protection or vacuum device is required, and the processing can be carried out in the atmosphere. The energy consumption is low, the process is simple, and the manufacturing cost is low.

[0025] 4. This invention can prepare metal laminated composite materials with any number of layers, and can be combined with a CNC system and corresponding subtractive manufacturing processes to achieve the manufacturing of components of a certain shape. By changing the thickness of each foil layer, it is also possible to prepare metal laminated composite materials of arbitrary thickness with a certain number of layers.

[0026] 5. This invention can be used to rapidly prepare metal laminated composite materials with a consolidation speed of not less than 20 mm / s. Furthermore, the substrate adopts a controlled sliding operation, which has a high degree of automation and greatly saves time and labor costs.

[0027] 6. Current-assisted bidirectional ultrasonic consolidation can increase the diffusion distance of titanium and aluminum atoms at the interface of titanium-aluminum laminated composite materials to a greater distance than that of samples obtained by traditional consolidation methods. Through optimization of process parameters, the interface bonding rate is higher and the metallurgical bonding performance is better. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the device of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the electric actuator of the present invention;

[0030] Figure 3 This is a schematic diagram showing the connection between the electric actuator and the substrate of the present invention;

[0031] Wherein: 1-current-assisted heat source; 2-substrate; 3-slide groove; 4-metal foil; 5-upper ultrasonic pressure head; 6-lower ultrasonic pressure head; 7-controller; 8-motor; 9-push rod; 10-connecting block. Detailed Implementation

[0032] This invention provides a novel apparatus and method for rapidly preparing metal laminated composite materials at room temperature, addressing the shortcomings of traditional ultrasonic additive manufacturing processes, such as long preheating and cooling times, significant influence of environmental conditions on the processing, localized residual stress generation due to temperature changes, complex processing steps during consolidation, poor bonding of formed samples, slight consolidation cracks, foil adhesion damage, and limited plasticizing ability for high-strength metal materials, making it difficult to rapidly form metal laminated materials with higher strength and thickness. To enhance the processing capabilities of ultrasonic consolidation manufacturing technology and broaden its application scope to the consolidation forming of high-strength and thick metal foils, this invention proposes a new apparatus and method for preparing metal laminated composite materials using current-assisted synchronous coupling bidirectional ultrasonic consolidation, based on current processing forming theory and automatic control theory. This method utilizes two ultrasonic indenters working simultaneously to generate high-frequency ultrasonic vibrations in two directions. Combined with the electro-softening and resistive thermal softening effects brought about by current assistance, it promotes metal atom diffusion and dislocation movement, reduces metal deformation resistance, and improves metal plastic deformation capacity. Furthermore, by fixing the indenters and controlling the sliding operation of the substrate, it achieves rapid ultrasonic solidification and additive manufacturing of high-strength, thick metal foils at room temperature.

[0033] The technical solution of this invention is: a method for preparing multilayer composite materials by current-assisted bidirectional ultrasonic consolidation and synchronous coupling, the specific method including the following steps:

[0034] 1. First, prepare the metal foil required for consolidation. Clean the surface oil with ultrasonic cleaner and dry it for later use. The metal foil can be pure aluminum foil or TC4 titanium foil. The width of the foil is smaller than the width of the ultrasonic indenter. The thickness of TC4 titanium foil and pure aluminum foil can be 0.1~0.3mm. The substrate is generally made of aluminum and the size is 150 mm × 80 mm × 5 mm. Before consolidation, the oxide film of the substrate is cleaned by mechanical polishing and the sample is wiped with acetone and alcohol.

[0035] 2. Next, the positive and negative electrodes of the external current-assisted heat source are clamped at both ends of the metal foil and the substrate, forming a closed loop between the metal foil and the substrate. External heating is achieved using resistance heating. The current-assisted heat source is a hot-wire argon arc welding machine. During the consolidation process, the pressure head of the ultrasonic vibration device located directly below the metal foil and the substrate, and the pressure head in contact with the foil, work simultaneously to generate ultrasonic vibrations along the normal direction and along the axial direction of the pressure head. Simultaneously, the substrate connected to the end of the push rod and the fixed metal foil slide along the groove at a certain speed under the drive of the push rod. Under the high-frequency vibration of the fixed upper and lower pressure heads, the consolidation of single or multiple layers of titanium-aluminum foil is completed.

[0036] 3. Using a single-layer or double-layer metal foil as a consolidation unit, select appropriate process parameters for current-assisted ultrasonic consolidation. The main parameters are: upper ultrasonic indenter amplitude 25~30μm, consolidation pressure 2.0~2.5KN, lower ultrasonic indenter amplitude 32~36μm, consolidation speed (substrate sliding speed) 20mm / s, current 10~30A, and preheating temperature reaching 160℃.

[0037] 4. Repeat the above consolidation operation using the same consolidation unit laying method, and alternately consolidate several layers of titanium and aluminum metal foils on the substrate to obtain a current-assisted bidirectional ultrasonically consolidated titanium-aluminum laminated composite material.

[0038] The technical solution of the present invention will be described in detail below through specific embodiments:

[0039] TC4 foil and pure aluminum foil, both with a width smaller than the ultrasonic indenter width and a thickness of 0.1~0.3mm, were used. Surface oil stains were cleaned with an ultrasonic cleaner, and the metal foil was then wiped with acetone and alcohol to further remove surface dirt and grease, and dried for later use. Samples containing several consolidation units were prepared, with the Ti foil on top and the Al foil on the bottom, arranged in a "Ti foil-Al foil" configuration.

[0040] In the preparation of current-assisted bidirectional ultrasonic consolidation of titanium-aluminum laminated composite materials, the process parameters are as follows: upper indenter ultrasonic amplitude of 25~30μm, consolidation pressure of 2.0~2.5KN, lower indenter ultrasonic amplitude of 32~36μm, consolidation speed of 20mm / s, current of 10~30A, and preheating temperature of 160℃. A schematic diagram of the system apparatus is attached. Figure 1 .

[0041] like Figure 1The apparatus shown first uses clamping devices to apply clamping force to the metal foil to fix its position on the sliding substrate, maintaining the stability of the foil during the consolidation process. The positive and negative terminals of an external current-assisted heat source are connected to the clamping devices at both ends of the metal foil and the sliding substrate, respectively, forming a closed loop between the metal foil and the sliding substrate. The current is adjusted to preheat the sliding substrate to 160°C, and the temperature is kept constant, achieving the external heating assistance effect through current and resistance heating. The system begins the consolidation process. The consolidation parameters are set, and the lower ultrasonic indenter located directly below the metal foil and the sliding substrate, and the upper ultrasonic indenter in contact with the metal foil, work simultaneously to generate ultrasonic vibrations along the normal direction of the foil and along the axial direction of the upper ultrasonic indenter. Simultaneously, the substrate connected to the end of the push rod and the fixed metal foil slide along the groove at a certain speed under the drive of the push rod. Under the high-frequency vibration of the fixed upper and lower indenters, the consolidation of single or multiple layers of titanium-aluminum foil is completed.

[0042] The first foil unit was solidified using the above parameters, and this process was repeated to prepare several layers of titanium-aluminum laminated composite material.

Claims

1. An apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminate composites, characterized by: The system includes a current-assisted heat source (1), a substrate (2), and a chute (3). The two ends of the substrate (2) along the length direction are located in the chute (3). A metal foil (4) is provided on the substrate (2) along the length direction. An electric push rod is provided at the bottom of the chute (3) along the length direction of the substrate (2). The end of the electric push rod is connected to the substrate (2). The positive and negative poles of the current-assisted heat source (1) are clamped at the two ends of the metal foil (4) and the substrate (2). The top of the metal foil (4) and the bottom of the substrate (2) are respectively provided with an upper ultrasonic pressure head (5) that vibrates along the axial direction and a lower ultrasonic pressure head (6) that vibrates along the normal direction. The upper ultrasonic pressure head (5) and the lower ultrasonic pressure head (6) are in contact with the metal foil (4) and the substrate (2) respectively. The width of the metal foil (4) is smaller than the width of the upper ultrasonic pressure head (5). The current-assisted heat source (1) is a hot wire argon arc welding machine; The electric push rod includes a controller (7), a motor (8) and a push rod (9). The controller (7) is electrically connected to the motor (8), the output end of the motor (8) is connected to the push rod (9), and the end of the push rod (9) is connected to the base plate (2) through a connecting block (10). The upper ultrasonic indenter (5) is located directly above the metal foil (4), and the lower ultrasonic indenter (6) is located directly below the substrate (2).

2. The apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composites of claim 1, wherein: The metal foil (4) is located at the center of the substrate.

3. The apparatus for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials according to claim 1, characterized in that: The number of electric push rods is two, located at the bottom of the slide grooves (3) at both ends, and symmetrically arranged relative to the axis of the base plate (2).

4. A method for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials using the apparatus according to any one of claims 1 to 3, characterized in that: Includes the following steps: The first step is to prepare the metal foil required for solidification, clean the surface oil with ultrasonic cleaner and dry it for later use, clean the oxide film of the substrate by mechanical polishing, and wipe it with acetone and alcohol. Then lay the metal foil on the substrate as required. The second step involves clamping the positive and negative electrodes of the externally applied current-assisted heat source to both ends of the metal foil and the substrate, respectively, to form a closed circuit between the metal foil and the substrate for preheating. In the third step, the lower ultrasonic pressure head located directly below the metal foil and the substrate, and the upper ultrasonic pressure head in contact with the metal foil, work simultaneously to generate ultrasonic vibrations along the normal and axial directions on the metal foil. At the same time, the substrate connected to the end of the push rod and the fixed metal foil slide along the groove under the drive of the push rod. Under the high-frequency vibration of the fixed upper and lower ultrasonic pressure heads, the metal foil consolidation work is completed.

5. The method for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials according to claim 4, characterized in that: The metal foil includes titanium foil and pure aluminum foil.

6. The method for current-assisted bidirectional ultrasonic additive manufacturing of metal laminated composite materials according to claim 4, characterized in that: The upper ultrasonic indenter has an ultrasonic amplitude of 25~30μm and a consolidation pressure of 2.0~2.5KN, the lower ultrasonic indenter has an ultrasonic amplitude of 32~36μm and a substrate sliding speed of 20mm / s, a closed-loop current of 10~30A, and a preheating temperature of 160℃.

Images