A self-supporting friction stir additive device integrating additive and subtractive functions

Abstract

A follow-up self-supporting stir friction additive device for integrated additive and subtractive materials. In order to solve the incompatibility problem in the process of integrated stir friction additive and subtractive materials using traditional magnesium alloys, aluminum alloys, and aluminum-based composite materials, the present invention includes a rotating component, a fixed component, a self-supporting structure, and a thrust bearing. The rotating component is rotatably connected to the fixed component, and the self-supporting structure and the thrust bearing are sequentially mounted on the lower part of the fixed component from top to bottom. The present invention has a wide range of applications and can be applied to a variety of lightweight metals and metal-based composite materials, including but not limited to magnesium, aluminum alloys, and aluminum-based composite materials. During the additive process, the metal wire raw material is processed from a solid state through crushing, extrusion, and transmission to a thermoplastic state without forming a liquid phase, which effectively suppresses the generation of defects such as pores, oxidation, and cracks. The metal matrix raw material wire and the reinforcing phase powder can be fed uninterruptedly, and the integrated continuous and stable preparation of large and complex structures can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-phase additive manufacturing, and in particular to a follow-up self-supporting stir friction additive device that integrates additive and subtractive processes. Background Art

[0002] my country's multiple launch vehicles will successively undertake major aerospace missions, placing increasingly stringent demands on vehicle performance. Efficient and reliable manufacturing of large, variable-section, curved, thin-walled components, such as launch vehicle propellant tanks, is crucial for achieving high-volume launch missions. Manufacturing lightweight, high-strength, and tough load-bearing structural components made of magnesium alloys, aluminum alloys, and aluminum-based composites is a key technological approach to reducing vehicle weight and increasing payload capacity and flight speed. This demand necessitates the development of materials for aerospace components that are higher in strength and lower in density, structures that are more integrated and thin-walled, and processing methods that are more efficient, cost-effective, and environmentally friendly. This places even higher demands on aerospace metal component manufacturing technologies. Direct plastic forming and melt additive manufacturing of complex structures face significant challenges due to the inherent characteristics of magnesium alloys, such as their high-temperature oxidation susceptibility and poor low-temperature toughness, as well as the difficulty of deformation and precision control in metal-based composites. Furthermore, traditional additive-then-subtractive processes for structural components suffer from long cycle times and low efficiency. There is an urgent need to achieve breakthroughs in new processes and methods for the integrated additive and subtractive manufacturing of high-strength and toughness magnesium alloys, aluminum alloys and metal matrix composite materials.

[0003] Friction stir additive-subtractive manufacturing (FSAM) technology consists of both additive and subtractive components. The additive component is characterized by low temperatures and high plastic deformation. The material remains solid throughout the entire process, avoiding melting and solidification. The high-strain-rate "forging" action of the additive tooling creates a fine-grained structure. This structure exhibits no solidification defects, a uniform structure, and low residual stresses, offering significant advantages in the additive manufacturing of high-performance aluminum-based composite components. The subtractive component utilizes a robotic arm to coordinate the fabrication of the structural component during the additive process. However, FSM AM still faces certain technical hurdles. First, the intense forging pressure of FSM requires sufficient backing support. The FSM process, however, requires simultaneous milling of the inner and outer walls of the additive component to remove excess material. This excess material is insufficient to support the additive process, leading to material collapse and hindering the process, necessitating the use of a support structure. However, for large, complex, and special-shaped structures, the existence and movement of the supporting structure have a significant impact on the degree of integration, which seriously restricts the application of the additive and subtractive integrated friction stir additive manufacturing method in lightweight structural parts. Summary of the Invention

[0004] The present invention aims to solve the problem that the strong forging effect in the stir friction additive manufacturing process can achieve the optimization of structure and performance, but requires a large back support force. The milling of the formed part in the process of additive and subtractive material integration will lead to insufficient support force required for additive manufacturing and cause material collapse, which seriously affects the additive process. In order to improve the degree of integration and realize the efficient preparation of complex special-shaped components, a follow-up self-supporting stir friction additive device and method with additive and subtractive material integration are proposed.

[0005] The technical solution adopted by the present invention to solve the above problems is:

[0006] The present invention includes a solid-phase additive manufacturing mechanism and a follow-up self-supporting mechanism. The solid-phase additive manufacturing mechanism includes a rotating part and a fixed part, and the rotating part is rotatably connected to the fixed part; the follow-up self-supporting mechanism includes a self-supporting structure and a thrust bearing, and the self-supporting structure and the thrust bearing are sequentially mounted on the lower part of the fixed part from top to bottom.

[0007] Furthermore, the rotating component includes a first clamping portion, a transition portion and a screw groove portion, and the first clamping portion, the transition portion and the screw groove portion are connected in sequence from top to bottom.

[0008] Furthermore, the side wall of the first clamping portion is provided with a milling plane; the side wall of the transition portion is provided with a disassembly groove; the side wall of the screw groove portion is provided with a feeding groove, and the bottom of the screw groove portion is provided with a stirring pin.

[0009] Furthermore, the fixing component includes a second clamping portion, a conveying portion and a shoulder portion, and the second clamping portion, the conveying portion and the shoulder portion are connected in sequence from top to bottom.

[0010] Furthermore, the upper surface of the second clamping part is provided with a plurality of first positioning holes evenly distributed along the circumferential direction; the side wall of the conveying part is provided with a wire feeding hole, and the bottom of the conveying part is provided with a limiting plane; positioning planes are provided on both sides of the shoulder part, second positioning holes are provided on the positioning plane, and a shoulder plane is provided at the bottom of the shoulder part.

[0011] Furthermore, the self-supporting structure includes a driven part, a supporting part and a driving part, wherein the lower surface of the driven part is connected to the supporting part, and the upper surface is connected to the driving part.

[0012] Furthermore, the support portion includes two columns and two support wheels, the inner ends of the two columns are provided with an assembly plane, and the lower part of the assembly plane is provided with a support wheel.

[0013] Furthermore, the thrust bearing includes an upper ring, a lower ring, balls and a retaining frame. The balls are installed between the upper ring and the lower ring through the retaining frame. Two ear plates are relatively provided at the lower end of the lower ring, and each ear plate is provided with a screw hole for installing a fixing component.

[0014] Furthermore, the diameter of the wire feeding hole is 1-4 mm.

[0015] Furthermore, the stirring needle is truncated cone-shaped, and the number of stirring needles is 2-4; the length of the stirring needle is 1.0-2.0 mm.

[0016] The beneficial effects of the present invention are:

[0017] 1. The present invention adopts the design of a follow-up self-supporting stir friction additive manufacturing mechanism that integrates additive and subtractive materials, adapts to the process requirements of additive and subtractive materials integration, and improves the production efficiency of additive components;

[0018] 2. The present invention transforms sliding friction into rolling friction by introducing a support wheel structure, thereby reducing the motion resistance under load and solving the problem of insufficient back support force in the integrated process of friction stir additive and subtractive material processing. While milling additive structural parts on demand, it ensures the stability of the additive process and realizes the one-step forming of high-performance complex and special-shaped structural parts.

[0019] 3. The present invention realizes the follow-up adjustment of the self-supporting mechanism through the cooperation of the driving part and the driven part of the follow-up self-supporting structure, adapts to the complex path requirements of special-shaped components, and enables the integrated augmentation and subtraction device to achieve a smooth transition of the self-supporting structure at the turning point;

[0020] 4. The present invention connects the self-supporting component of the follower self-supporting structure with the friction stir additive manufacturing device through a thrust bearing, thereby avoiding wear, improving displacement speed and sensitivity, and enabling real-time adjustment of the position of the self-supporting component to meet complex additive path requirements, thereby improving the forming quality and efficiency of the additive structure.

[0021] 5. The present invention has a wide range of applications and can be applied to a variety of lightweight metals and metal-based composites, including but not limited to magnesium, aluminum alloys, and aluminum-based composites. During the additive process, the metal wire feedstock undergoes a process from a solid state through crushing, extrusion, and conveying to a thermoplastic state without forming a liquid phase, effectively suppressing the formation of defects such as porosity, oxidation, and cracks. The metal matrix feedstock wire and reinforcement powder can be fed continuously, enabling the integrated, continuous, and stable fabrication of large, complex structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the rotating component of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the fixing component of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the self-supporting component of the present invention;

[0026] Figure 5 It is a structural schematic diagram of the thrust bearing component of the present invention.

[0027] In the figure: 1-rotating component, 101-clamping part, 10101-side milling plane, 102-transition part, 10201-disassembly groove, 103-screw groove part, 10301-feeding trough, 10302-stirring needle;

[0028] 2-fixed part, 201-clamping part, 20101-positioning through hole, 202-transport part, 20201-wire feeding hole, 20202-limiting plane, 203-shoulder part, 20301-positioning plane, 20302-positioning hole, 20303-shoulder plane

[0029] 3-metal wire raw materials;

[0030] 4- self-supporting component, 401- driven part, 40101- transmission gear, 40102- limiting plane, 402- supporting part, 40201- assembly plane, 40202- supporting wheel, 403- driving part;

[0031] 5-thrust bearing, 501-upper ring, 50101-ball guide rail, 502-middle, 50201-cage, 50202-ball, 503-lower ring, 50301-positioning plane, 50302-ball guide rail, 50303-fixing screw hole;

[0032] 6-Increase and reduce material integrated structural parts;

[0033] 7-Double-sided end mill;

[0034] 8-Substrate. DETAILED DESCRIPTION

[0035] Specific implementation method 1: Combination Figure 1 This embodiment describes a follow-up self-supporting stir friction additive device with integrated additive and subtractive functions, comprising a solid-phase additive manufacturing mechanism and a follow-up self-supporting mechanism. The solid-phase additive manufacturing mechanism comprises a rotating component 1 and a fixed component 2, wherein the rotating component 1 is rotatably connected to the fixed component 2. The follow-up self-supporting mechanism comprises a self-supporting structure 4 and a thrust bearing 5, which are sequentially mounted on the lower portion of the fixed component 2 from top to bottom. The rotating component 1 is used to connect to the rotating spindle rotor portion of the machining equipment; the fixed component 2 is used to connect to the non-rotating portion of the spindle of the machining equipment, and the orientation of the fixed component 2 does not change. The self-supporting component 4 is located above the thrust bearing 5 to avoid rigid grinding under stress.

[0036] Specific implementation method 2: Combination Figure 2To describe this embodiment, the rotating component 1 in this embodiment includes a first clamping portion 101 , a transition portion 102 and a screw groove portion 103 , and the first clamping portion 101 , the transition portion 102 and the screw groove portion 103 are sequentially connected from top to bottom. The first clamping part 101 is used to connect with the rotating spindle rotor part of the machining equipment. The side wall of the first clamping part 101 is provided with a milling plane 10101 for side clamping; the transition section 102 is used to connect the first clamping part 101 and the screw groove part 103 and realize the clamping and positioning of the rotating part 1. The side wall of the transition part 102 is provided with a disassembly groove 10201 for installation and disassembly. The screw groove part 103 is inserted in the fixed part 2. The screw groove part 103 is provided with a feeding groove 10301, which is used to feed and extrude the additive metal wire raw material 3 fed from the wire feeding hole 20201 of the fixed part 2 toward the stirring needle 10302, and in the process, the additive metal wire raw material 3 is broken and thermoplasticized, and then densely formed under the large plastic deformation of the stirring needle 10302. A truncated cone-shaped stirring needle 10302 is provided at the bottom of the screw groove portion 103, which is used to achieve excellent bonding between the additive layers and solve the anisotropy problem commonly found in existing additive processes. At the same time, it can achieve uniform dispersion of the reinforcing phase in the metal matrix through large plastic deformation, thereby improving the comprehensive mechanical properties of the additive structural part 6.

[0037] Preferably, the screw groove portion 103 in the rotating component 1 uses but is not limited to single, double internal screw grooves and external screw structures.

[0038] Preferably, a frustum-shaped stirring pin 10302 is provided at the bottom of the screw groove portion 103, and the number thereof is generally 2 to 4. The length of the stirring pin is selected according to the set thickness of the additive layer, and is generally 1.0 to 2.0 mm.

[0039] The other components and connection relationships of this embodiment are the same as those of the first embodiment.

[0040] Specific implementation method three: Combination Figure 3 In this embodiment, the fixing member 2 includes a second clamping portion 201, a conveying portion 202, and a shoulder portion 203, which are connected in sequence from top to bottom. The upper surface of the second clamping portion 201 is provided with a plurality of first positioning holes 20101 evenly distributed along the circumference; the second clamping portion 201 is used to connect to the non-rotating portion of the main shaft of the processing equipment.

[0041] A wire feeding hole 20201 is provided on the side wall of the conveying part 202, and the metal wire raw material 3 is fed into the internal cavity through the wire feeding hole 20201 on the side of the conveying part 202. The wire feeding hole 20201 obliquely penetrates the side wall of the fixed part 2 downward, and the internal hole height is lower than the starting end of the screw groove of the rotating part 1, ensuring the smooth crushing and conveying of the wire; a limiting plane 20202 is provided at the bottom of the conveying part 202 to avoid interference between the support structure 4 and the wire raw material 3; a positioning plane 20301 is provided on the shoulder part 203 to limit the circumferential rotation of the lower ring 503 of the thrust bearing 5, and a second positioning hole 20302 is provided on the positioning plane 20301. The positioning plane 20301 and the positioning hole 20302 are used to position and fix the thrust bearing 5 in the self-supporting mechanism; a shoulder plane 20303 is provided at the bottom of the shoulder part 203 to compact and smooth the thermoplasticized additive raw material in the stirring needle 10302 of the rotating part 1.

[0042] Preferably, the diameter of the wire feeding hole 20201 of the conveying portion 202 is 1-4 mm, so as to be suitable for metal wire raw materials 3 of different sizes and powder core wires containing a reinforcement phase;

[0043] Preferably, the shaft shoulder portion 203 of the fixed component 2 is flush with the end surface of the screw groove portion 103 of the rotating component 1 .

[0044] The other components and connection relationships of this embodiment are the same as those of the first or second embodiment.

[0045] Specific implementation method four: Combination Figure 4 To illustrate this embodiment, the self-supporting structure 4 described in this embodiment includes a driven part 401, a supporting part 402 and a driving part 403. The lower surface of the driven part 401 is connected to the supporting part 402, and is displaced during the process of adding or subtracting material to achieve self-support for complex special-shaped structures. The upper surface of the driven part 401 is connected to the driving part 403.

[0046] The driving part 403 is a driving gear, fixedly connected to the output shaft of the motor. The motor is fixed to the fixed component 2 and drives the driven part 401 to change position by rotating forward or reverse at a specific speed.

[0047] The driven portion 401 comprises a circular ring and a driven gear 40101. The upper surface of the circular ring is provided with the driven gear 40101, which meshes with the driving gear. The inner side of the driven gear 40101 defines a limiting surface 40102. The lower surface of the circular ring is connected to the upper ends of the two columns of the support portion 402. The support portion 402 comprises two columns and two support wheels 40202. The inner ends of each column are provided with an assembly surface 40201. Support wheels 40202 are located below the assembly surface 40201. These two support wheels 40202 convert sliding friction into rolling friction to reduce resistance during the additive process.

[0048] The support wheel 40202 is height-adjustable and can be opened to both sides to avoid interference between the starting pass and the substrate. At the same time, the height can be set according to the needs of additive and subtractive material integration to provide sufficient back support force; the support wheel 40202 structure changes sliding friction into rolling friction, reducing the movement resistance under the action of load, solving the problem of insufficient back support force in the process of stir friction additive and subtractive material integration, and ensuring the stability of the additive process while milling additive structural parts on demand, realizing the one-time forming of high-performance complex special-shaped structural parts.

[0049] Preferably, the driving part 403 and the driven part 401 adopt a transmission including but not limited to a helical gear transmission and a spur gear transmission to achieve a smooth transmission process under a certain load;

[0050] Preferably, the support wheel 40202 is made of materials including but not limited to steel and cemented carbide, and measures such as coating the surface of the support wheel 40202 with graphite or molybdenum disulfide powder are taken to avoid adhesion with the additive layer and reduce friction.

[0051] The other components and connection relationships of this embodiment are the same as those of the first, second or third embodiment.

[0052] Specific implementation method five: Combination Figure 5 To explain this embodiment, the thrust bearing 5 comprises an upper ring 501, a lower ring 503, balls 50202, and a retainer 50201. The balls 50202 are mounted between the upper and lower rings 501, 503, via the retainer 50201. The lower ring 503 has two lugs on its inner ends, each with a screw hole 50303 for connection to the fixed component 2 in the additive mechanism. The upper ring 501 of the thrust bearing 5 contacts and supports the driven component 401, ensuring smooth displacement and minimizing wear. The balls 50202 roll between the upper and lower rings 501, 503, bearing axial loads and reducing friction. The retainer 50201 separates the balls 50202, ensuring even distribution and preventing collisions.

[0053] The other components and connection relationships of this embodiment are the same as those of the first, second, third, fourth or fifth embodiment.

[0054] Specific implementation method six: combination Figures 1 to 5 To illustrate this embodiment, the self-supporting friction stir additive device integrating additive and subtractive processes is implemented by the following steps:

[0055] Step 1: Feed the metal wire material 3 into the cavity between the fixed component 2 and the rotating component 1 through the wire feeding hole 20201. Then, it is sheared and broken into metal segments under the high-speed rotation of the screw groove portion 103 of the rotating component 1, and finally transported downward along the screw groove under the action of gravity;

[0056] Step 2: The crushed metal segments accumulate continuously inside the screw groove 10301 and are further rubbed and deformed by the extrusion of the screw groove portion 103 of the rotating component 1, generating heat and thermoplasticizing. The thermoplasticized material is deposited and formed by the forging action of the shaft shoulder 203 of the fixed component 2 and cooling by external airflow. Simultaneously, the high-speed rotation of the stirring pin 10302 of the rotating component 1 ensures sufficient material flow and reliable interlayer bonding.

[0057] Step 3: When the material is added to a certain height, the subtraction operation is started according to the requirements of the structural part 6. Milling cutters 7 are set on both sides of the integrated structure 6 for adding and subtracting materials. The milling cutter 7 is controlled by a robotic arm to mill the required wall thickness toward the center. During the subtraction process, the back support force provided by the additive part decreases due to the thinning of the wall thickness. The follow-up self-supporting mechanism 4 is lowered to achieve self-support and avoid the collapse of the deposited material. The height of the support wheel 40202 is adjusted according to the degree of material reduction, and the support wheel 40202 is used to reduce the resistance to the additive movement;

[0058] Step 4: When the additive device reaches the turning point, the driving part 403 of the follower self-supporting mechanism 4 is started, driving the driven part 401 to rotate in the additive direction, realizing the conversion of the support direction, avoiding interference and improving production efficiency.

[0059] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A self-supporting friction stir additive device integrating additive and subtractive processes, characterized by: The device comprises a solid-phase additive manufacturing mechanism and a follow-up self-supporting mechanism, wherein the solid-phase additive manufacturing mechanism comprises a rotating component (1) and a fixed component (2), wherein the rotating component (1) is rotatably connected to the fixed component (2); and the follow-up self-supporting mechanism comprises a self-supporting structure (4) and a thrust bearing (5), wherein the self-supporting structure (4) and the thrust bearing (5) are sequentially mounted on the lower part of the fixed component (2) from top to bottom.

2. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 1, characterized in that: The rotating component (1) comprises a first clamping portion (101), a transition portion (102) and a screw groove portion (103), and the first clamping portion (101), the transition portion (102) and the screw groove portion (103) are connected in sequence from top to bottom.

3. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 2, characterized in that: The side wall of the first clamping portion (101) is provided with a milling plane (10101); the side wall of the transition portion (102) is provided with a disassembly groove (10201); the side wall of the screw groove portion (103) is provided with a feeding groove (10301), and the bottom of the screw groove portion (103) is provided with a stirring needle (10302).

4. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 1, characterized in that: The fixing component (2) comprises a second clamping portion (201), a conveying portion (202) and a shoulder portion (203), and the second clamping portion (201), the conveying portion (202) and the shoulder portion (203) are connected in sequence from top to bottom.

5. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 4, characterized in that: The upper surface of the second clamping portion (201) is uniformly provided with a plurality of first positioning holes (20101) along the circumferential direction; the side wall of the conveying portion (202) is provided with a wire feeding hole (20201), and the bottom of the conveying portion (202) is provided with a limiting plane (20202); positioning planes (20301) are provided on both sides of the shoulder portion (203), second positioning holes (20302) are provided on the positioning plane (20301), and the bottom of the shoulder portion (203) is provided with a shoulder plane (20303).

6. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 1, characterized in that: The self-supporting structure (4) comprises a driven part (401), a supporting part (402) and a driving part (403); the lower surface of the driven part (401) is connected to the supporting part (402), and the upper surface is connected to the driving part (403).

7. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 6, characterized in that: The support portion (402) comprises two columns and two support wheels (40202), the inner ends of the two columns are provided with an assembly plane (40201), and the lower part of the assembly plane (40201) is provided with a support wheel (40202).

8. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 1, characterized in that: The thrust bearing (5) comprises an upper ring (501), a lower ring (503), a ball (50202) and a retaining frame (50201), wherein the ball (50202) is mounted between the upper ring (501) and the lower ring (503) via the retaining frame (50201), and two lugs are provided at the lower end of the lower ring (503), each of which is provided with a screw hole (50303) for mounting a fixing component (2).

9. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 5, characterized in that: The diameter of the wire feeding hole (20201) is 1-4mm.

10. The self-supporting friction stir additive device with integrated additive and subtractive functions according to claim 3, characterized in that: The stirring needle (10302) is in the shape of a truncated cone, and the number of the stirring needles (10302) is 2-4; the length of the stirring needle (10302) is 1.0-2.0 mm.

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