Friction stir welding additive manufacturing method and system based on aluminum alloy extrusion

Abstract

The invention discloses a friction stir welding additive manufacturing method and system based on aluminum alloy extrusion, and belongs to the field of metal additive manufacturing. According to the method, aluminum alloy extrusion forming and friction stir welding are combined, and semi-solid aluminum ingots are continuously and stably provided as additive raw materials through an extrusion device; the material is driven to flow downwards through the relative rotation movement of the stirring needle and the shaft shoulder, and solid metallurgical bonding between the material and a substrate / deposition layer is achieved under the action of friction heat and pressure; a computer controls the shaft shoulder to move in a plane according to a set path and lift layer by layer, and layered deposition of the three-dimensional component is completed. According to the method, the limitation that traditional friction stir welding has no automatic feeding capacity is broken through, continuous and automatic material adding is achieved, the defects of air holes and cracks of melting type material adding are avoided, and the forming efficiency and quality of large-size complex aluminum alloy components are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and in particular relates to a stir friction welding additive manufacturing method and system based on aluminum alloy extrusion. Background Art

[0002] Metal additive manufacturing technology forms solid components by accumulating materials layer by layer. Compared with traditional casting and forging processes, it has advantages such as high material utilization, greater design freedom, and shorter production cycles. It is particularly suitable for the manufacture of complex geometric structures and lightweight products. Current mainstream metal additive technologies (such as laser selective melting and arc fuse additive manufacturing) rely on high-energy heat sources to melt materials, but have significant drawbacks when applied to aluminum alloys: Metallurgical defects: During the rapid cooling and solidification process, molten aluminum alloy is prone to produce pores (due to difficulty in gas escape), thermal cracks (due to shrinkage stress) and element segregation, resulting in a decrease in the density of the formed part; Deterioration of structural properties: Coarse grain structure makes it difficult for mechanical properties (such as strength and toughness) to meet the requirements of high-performance components; Expansion of the heat-affected zone: High heat input introduced by high-energy heat sources can easily cause tissue overheating, expand the heat-affected zone, and affect dimensional accuracy.

[0003] Friction stir additive manufacturing (FSAM), as a solid-state forming technology, uses a rotating stirrer to pressurize the material to cause thermoplastic flow and achieve metallurgical bonding between layers. This technology has obvious advantages: Avoid melting-solidification defects, the formed parts have extremely low porosity and no element segregation; Significant grain refinement effect and excellent mechanical properties; Low heat input, narrow heat-affected zone and controllable deformation.

[0004] However, its inherent limitations restrict its industrial application: Friction stir welding itself does not have the ability to supply materials and needs to rely on external feeding devices (such as robotic arm wire feeding), which leads to process interruptions and poor interlayer bonding stability, making it difficult to achieve continuous and efficient manufacturing of large-scale components.

[0005] Aluminum alloy extrusion technology applies strong axial pressure to aluminum ingots through a die, causing them to undergo directional plastic deformation and continuous extrusion. This technology offers near-net-shape formation, minimal material loss, and a high degree of automation, making it suitable for mass production. However, this technology can only produce billets and cannot directly achieve dense interlayer connections in complex three-dimensional structures.

[0006] In summary, the existing technology has the following gaps: Traditional melting additive manufacturing is difficult to solve the metallurgical defects of aluminum alloys; Friction stir additive manufacturing lacks a continuous and stable material supply system; Extrusion molding technology cannot independently complete the additive manufacturing of complex structures.

[0007] Therefore, it is urgent to develop a new method for additive manufacturing of aluminum alloys that combines continuous feeding and solid-state forming to break through the above technical bottlenecks. Summary of the Invention

[0008] The purpose of the embodiments of the present invention is to provide a stir friction welding additive manufacturing method and system based on aluminum alloy extrusion. It innovatively integrates the metal extrusion process with the principle of molten deposition, proposes a deposition additive molding method using aluminum ingots as direct raw materials, and introduces the extrusion process into the molten deposition system for the first time, providing an industrially feasible path for high-melting-point metal additive manufacturing, thereby solving at least one technical problem involved in the background technology.

[0009] In order to solve the above-mentioned technical problems, the present invention is achieved as follows: An embodiment of the present invention provides a friction stir welding additive manufacturing method based on aluminum alloy extrusion, comprising the following steps: Step S1, preheating the substrate; Step S2, preheating the aluminum ingot into a semi-solid state, and then applying an axial force through an extrusion device to force the semi-solid aluminum ingot into a reaction chamber; Step S3, the semi-solid aluminum ingot is continuously extruded by the extrusion device, while the stirring pin and the shaft shoulder are driven by the second servo motor to perform rotation, lifting and translation motions; Step S4: The computer controls the shoulder to move along a preset path, and the extruded semi-solid aluminum ingot generates heat by friction with the substrate and the shoulder to form a semi-solid plastic aluminum material, and then a single layer of the semi-solid plastic aluminum material is deposited on the substrate; In step S5, after completing the single-layer deposition, the shoulder moves up one layer, and step S4 is repeated to perform secondary deposition on the previous layer of deposition material. The stirring head then extends into the front and rear layers of deposition material, and stirs the softened two layers of deposition material while rotating and moving, so that the two layers of deposition material are fully mixed until a three-dimensional component is formed.

[0010] Optionally, in step S2, the extrusion device includes a first servo motor, an extrusion rod driven by the first servo motor, an extrusion pad installed at the bottom end of the extrusion rod, and an extrusion cylinder cooperating with the extrusion pad, and the extrusion pressure range is 50-500 MPa.

[0011] Optionally, the reaction crucible and sleeve in step S2 are equipped with a heating device.

[0012] Optionally, in step S3, the rotation speeds of the stirring needle and the shaft shoulder are independently controllable, and the rotation speed range is 200-2000 rpm.

[0013] Optionally, in step S4, the frictional heat generates so that the material temperature reaches the plasticizing temperature range of the aluminum alloy, specifically 60%-90% of the melting point of the material.

[0014] Optionally, in step S5, the height of the shoulder upward movement is 1.0-1.2 times the thickness of the single layer deposition, and the thickness of the single layer is 2-10 mm.

[0015] The present invention also provides an aluminum alloy extrusion-based friction stir welding additive manufacturing system for implementing the method, comprising: A substrate preheating module, used for preheating the substrate; An extrusion device comprises a first servo motor, an extrusion rod driven by the first servo motor, an extrusion pad mounted on the bottom end of the extrusion rod, and an extrusion cylinder matched with the extrusion pad; A reaction chamber comprising a reaction crucible and a sleeve with a heating device; The friction stir welding head includes a counter-rotating stirring pin and a shaft shoulder, and the side wall of the stirring pin is provided with a thread; The three-dimensional motion platform is controlled by a computer to realize the plane motion of the friction stir welding head; Layer height control module, used to raise the friction stir welding head layer by layer.

[0016] Optionally, the stirring needle and the shaft shoulder are driven by an independent first servo motor and rotate in opposite directions.

[0017] Optionally, the heating device is an induction heater or a resistance heater with a temperature control accuracy of ±10°C.

[0018] The present invention also provides a large complex aluminum alloy component manufactured by the method, wherein the internal grain size of the component is ≤20 μm, the porosity is ≤0.5%, and the tensile strength is ≥300 MPa.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention innovatively combines aluminum alloy extrusion molding with stir friction welding additive manufacturing. Continuous and stable feeding of aluminum ingots is achieved through the extrusion device, which completely solves the technical bottleneck of traditional stir friction welding, which cannot independently complete additive manufacturing due to its lack of independent feeding capability, and significantly expands the application scope of stir friction welding in the field of additive manufacturing.

[0020] 2. The present invention utilizes the solid-state plasticization connection characteristics of stir friction welding to achieve interlayer metallurgical bonding under the action of thermal-mechanical coupling, effectively avoiding defects such as pores, cracks, element segregation and grain coarsening caused by the melting-solidification process in traditional fusion welding additive manufacturing (such as laser / arc melting), and obtains aluminum alloy components with dense structure, refined grains and excellent mechanical properties.

[0021] 3. The extrusion process of the present invention provides a large flow of material input, supports the rapid forming of large-sized and complex structural parts, and significantly improves manufacturing efficiency; directly uses aluminum ingots as raw materials, eliminating the wire preparation process and reducing raw material costs. At the same time, the extrusion process itself has the advantages of near-net forming and low material loss, and the material utilization rate is significantly higher than that of traditional additive processes.

[0022] 4. The high fluidity of the extrusion feeding of the present invention and the high density of stir friction welding work synergistically to suppress deformation and structural coarsening during the forming process; the second servo motor precisely controls the synchronous movement (rotation, lifting, and translation) of the extrusion rod and the stirring needle, combined with computer path planning, to achieve automated continuous production, providing a reliable technical foundation for the batch manufacturing of large structural parts.

[0023] 5. The present invention is suitable for the one-piece forming of large aluminum alloy components in the fields of aerospace, rail transportation, etc., reducing the need for subsequent machining; it has unique advantages in repair, remanufacturing and connection of dissimilar materials, reducing maintenance costs; the process is green and low-carbon, without welding fume pollution, and is in line with the trend of sustainable manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which: Figure 1 A schematic structural diagram of a friction stir welding additive manufacturing system based on aluminum alloy extrusion provided by an embodiment of the present invention; Figure 2 Flowchart of a friction stir welding additive manufacturing method based on aluminum alloy extrusion provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] The terms "first," "second," and the like in the specification and claims of the present invention are used to distinguish similar objects, and are not used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present invention can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," and the like are generally of the same type, and do not limit the number of objects. For example, the first object can be one or more. In addition, the term "and / or" in the specification and claims refers to at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship.

[0027] See Figure 1 As shown, the present invention provides a stir friction welding additive manufacturing system based on aluminum alloy extrusion, including a substrate preheating module, an extrusion device, a reaction chamber, a stir friction welding head, a three-dimensional motion platform and a layer height control module.

[0028] The substrate preheating module is used to preheat the substrate 1, which can improve the interface bonding.

[0029] The extrusion device includes a first servo motor 2 , an extrusion rod 3 driven by the first servo motor 2 , an extrusion pad 4 installed at the bottom end of the extrusion rod 3 , and an extrusion cylinder 5 matched with the extrusion pad 4 .

[0030] The reaction chamber includes a reaction crucible 7 with a heating device 6 and a sleeve 8 , wherein the sleeve 8 is connected to the bottom opening of the reaction crucible 7 .

[0031] Specifically, the heating device 6 is an induction heater or a resistance heater, and the temperature control accuracy is ±10°C.

[0032] The friction stir welding head includes a stirring needle 9 and a shaft shoulder 10 that can rotate in opposite directions. The side wall of the stirring needle 9 is provided with a thread 91.

[0033] In a specific embodiment, the stirring needle 9 and the shaft shoulder 10 are driven by an independent first servo motor and rotate in opposite directions.

[0034] The friction stir welding head further includes a stirring head 92 located at the bottom end of the stirring needle 9 .

[0035] The three-dimensional motion platform is controlled by the computer 11 to realize the planar motion of the friction stir welding head.

[0036] The layer height control module is used to lift the friction stir welding head layer by layer.

[0037] Recombination Figure 2 As shown, the present invention also provides a stir friction welding additive manufacturing method based on aluminum alloy extrusion, comprising the following steps: Step S1, preheating the substrate 1; Step S2, preheating the aluminum ingot 12 into a semi-solid state, and then applying an axial force through an extrusion device to force the semi-solid aluminum ingot 13 into a reaction chamber; Step S3, the semi-solid aluminum ingot 13 is continuously extruded by the extrusion device, while the stirring pin 9 and the shaft shoulder 10 are driven by a second servo motor (not shown) to perform rotation, lifting and translation movements; Step S4: The computer controls the shoulder 10 to move in a plane along a preset path. The extruded semi-solid aluminum ingot 13 generates heat by friction with the substrate 1 and the shoulder 10 to form a semi-solid plastic aluminum material. The semi-solid plastic aluminum material is then deposited as a single layer on the substrate 1. In step S5, after completing the single-layer deposition, the shoulder moves up one layer, and step S4 is repeated to perform secondary deposition on the previous layer of deposition material 14. The stirring head then extends into the front and rear layers of deposition material 14, and stirs the softened two layers of deposition material 14 while rotating and moving, so that the two layers of deposition material 14 are fully mixed, the oxide film is destroyed, and the quality of the additive part is improved until a three-dimensional component is formed.

[0038] In step S2, the extrusion device includes a first servo motor 2, an extrusion rod 3 driven by the first servo motor 2, an extrusion pad 4 installed at the bottom end of the extrusion rod 3, and an extrusion cylinder 5 matched with the extrusion pad 4, and the extrusion pressure range is 50-500MPa.

[0039] The reaction chamber includes a reaction crucible 7 with a heating device 6 and a sleeve 8.

[0040] In step S3, the rotation speed of the stirring needle 9 and the shaft shoulder 10 is controlled by a second servo motor, and the speed range is 200-2000 rpm.

[0041] In step S4, the frictional heat generates so that the material temperature reaches the plasticizing temperature range of the aluminum alloy, specifically 60%-90% of the melting point of the material.

[0042] It should be further explained that in step S4 , the shoulder 10 starts to move in a planar manner to perform single-layer deposition only after the semi-solid plastic aluminum material fills the preset gap between the shoulder 10 and the substrate 1 .

[0043] In step S5, the shoulder 10 is moved upward to a height of 1.0-1.2 times the thickness of the single layer deposition, and the thickness of the single layer is 2-10 mm.

[0044] The present invention also provides a large complex aluminum alloy component manufactured by the method, wherein the internal grain size of the component is ≤20 μm, the porosity is ≤0.5%, and the tensile strength is ≥300 MPa.

[0045] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0046] Furthermore, it should be noted that the scope of the methods and systems of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in reverse order, depending on the functions involved. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to certain examples may be combined in other examples.

[0047] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A friction stir welding additive manufacturing method based on aluminum alloy extrusion, characterized in that: The steps include: Step S1, preheating the substrate; Step S2, preheating the aluminum ingot into a semi-solid state, and then applying an axial force through an extrusion device to force the semi-solid aluminum ingot into a reaction chamber; Step S3, the semi-solid aluminum ingot is continuously extruded by the extrusion device, while the stirring pin and the shaft shoulder are driven by the second servo motor to perform rotation, lifting and translation motions; Step S4: The computer controls the shoulder to move along a preset path, and the extruded semi-solid aluminum ingot generates heat by friction with the substrate and the shoulder to form a semi-solid plastic aluminum material, and then a single layer of the semi-solid plastic aluminum material is deposited on the substrate; In step S5, after completing the single-layer deposition, the shoulder moves up one layer, and step S4 is repeated to perform secondary deposition on the previous layer of deposition material. The stirring head then extends into the front and rear layers of deposition material, and stirs the softened two layers of deposition material while rotating and moving, so that the two layers of deposition material are fully mixed until a three-dimensional component is formed.

2. The method according to claim 1, characterized in that In step S2, the extrusion device includes a first servo motor, an extrusion rod driven by the first servo motor, an extrusion pad installed at the bottom end of the extrusion rod, and an extrusion cylinder matched with the extrusion pad, and the extrusion pressure range is 50-500 MPa.

3. The method according to claim 1 or 2, characterized in that In step S2, a reaction crucible and a sleeve are provided with a heating device.

4. The method according to claim 1, wherein In step S3, the rotation speeds of the stirring needle and the shaft shoulder are independently controllable, and the rotation speed range is 200-2000 rpm.

5. The method according to claim 1, wherein In step S4, the frictional heat generates so that the material temperature reaches the plasticizing temperature range of the aluminum alloy, specifically 60%-90% of the melting point of the material.

6. The method according to claim 1, wherein In step S5, the height of the shoulder upward movement is 1.0-1.2 times the thickness of the single layer deposition, and the thickness of the single layer is 2-10 mm.

7. A friction stir welding additive manufacturing system based on aluminum alloy extrusion for implementing the method according to any one of claims 1 to 6, characterized in that: include: A substrate preheating module, used for preheating the substrate; An extrusion device comprises a first servo motor, an extrusion rod driven by the first servo motor, an extrusion pad mounted on the bottom end of the extrusion rod, and an extrusion cylinder matched with the extrusion pad; A reaction chamber comprising a reaction crucible and a sleeve with a heating device; The friction stir welding head includes a counter-rotating stirring pin and a shaft shoulder, and the side wall of the stirring pin is provided with a thread; The three-dimensional motion platform is controlled by a computer to realize the plane motion of the friction stir welding head; Layer height control module, used to raise the friction stir welding head layer by layer.

8. The system according to claim 7, characterized in that The stirring needle and the shaft shoulder are driven by an independent first servo motor and rotate in opposite directions.

9. The system according to claim 7, wherein: The heating device is an induction heater or a resistance heater, and the temperature control accuracy is ±10°C.

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