Ultrasonic friction stir solid-phase additive manufacturing apparatus and method with inner wall of annular structure

Abstract

The application relates to the field of additive manufacturing technology and discloses an ultrasonic stirring friction solid-phase additive manufacturing device and method for an inner wall of a ring structure. An ultrasonic tool head is in contact with the side of a rotating stirring head through bearings at the end of the tool head, and ultrasonic vibration is vertically transmitted into the rotating stirring head. Wire is sent to the upper screw rod section of the stirring head through a wire feeding hole on a sleeve, the upper screw rod section shears the wire, the broken material is sent to the stirring needle part, the material is plasticized through friction between the stirring needle, the inner shaft shoulder and the material, and the plasticized material is gradually deposited on the inner wall of the ring structure under the wrapping of the static sleeve, so that layer-by-layer accumulation is realized. The application realizes high-quality and low-heat-input solid-phase additive manufacturing, can effectively inhibit the growth of intermetallic compounds at the interface of dissimilar metals, reduce workpiece deformation and residual stress, is suitable for the repair / strengthening of the same metal and the preparation of a dissimilar metal transition layer, and has low modification cost and is easy to popularize.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to an ultrasonic stirring friction solid-phase additive manufacturing apparatus and method for the inner wall of an annular structure. Background Technology

[0002] Wheel hub manufacturing primarily employs casting or forging processes. With lightweighting becoming a trend, "replacing steel with aluminum and aluminum with magnesium" has become a development direction. Some applications require dissimilar metal composite structures in wheel hubs; for example, using high-strength alloys for the annular bead seat to ensure reliable bonding with the tire, while replacing the spokes with low-strength alloys to meet lightweight requirements. However, traditional casting and forging methods have limitations in multi-material composite manufacturing.

[0003] The method of first casting / forging a high-strength alloy bead seat and then welding a low-strength alloy wheel spoke to the bead seat presents significant challenges. For fusion welding, the molten pool metal is difficult to stably form on the sidewalls and top under gravity, and is prone to flowing and collapsing; high heat input can easily lead to deformation of the thin-walled substrate and may damage the original heat treatment properties of the substrate material; for dissimilar metal welding, high heat input will promote the growth of hard and brittle intermetallic compounds (IMCs), severely impairing the mechanical properties of the joint.

[0004] Given the extreme difficulty of directly welding low-strength alloy wheel spokes to high-strength alloy bead seats, it would be more feasible to pre-prepare a low-strength alloy transition layer on the inner wall of the high-strength alloy bead seat before welding the spokes. If the method of first fabricating dissimilar metal composite plates and then rolling them into rings is adopted, it will generate extremely high internal stress. This not only makes it difficult to ensure the concentricity of the components, but the internal stress generated during plate rolling may also damage the microstructure of the composite interface, for example, causing cracks in the IMCs layer between the two metals in the composite plate, thereby drastically reducing the fatigue life of the components.

[0005] Patent application number 201811369000.3 discloses a hot isostatic pressing diffusion bonding method for bimetallic cylindrical components. This method involves nesting two metal cylinders, filling the gap between them with a powdered intermediate bonding material, and then placing them in a hot isostatic pressing apparatus for diffusion bonding under specific pressure and temperature. While this method partially solves the problem of excessively thick IMCs by adding an intermediate layer, it undoubtedly suffers from poor flexibility and low material utilization for scenarios where only a localized area of ​​the annular structure is needed. Furthermore, because the process requires prolonged high-temperature and high-pressure treatment of the entire workpiece, this can lead to changes in the microstructure and properties of the already heat-treated matrix material.

[0006] Therefore, there is an urgent need for an additive manufacturing device that can perform high-quality, low-heat-input, and locally formed additive manufacturing on the inner wall of a ring structure, and can be applied to both the repair / reinforcement of the same metal and the preparation of a transition layer of dissimilar metals. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an ultrasonic stirring friction solid-phase additive manufacturing apparatus and method for the inner wall of annular structures. This method enables high-quality, low-heat-input solid-phase additive manufacturing and is applicable not only to the additive manufacturing of a transition layer of another metal (such as a low-strength alloy) on the inner wall of a dissimilar metal annular matrix (such as a high-strength alloy) to solve the subsequent dissimilar metal welding problem, but also to the local repair, dimensional restoration, or performance enhancement of the inner wall of a homogeneous metal annular component.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, an ultrasonic stirring friction solid-phase additive manufacturing apparatus for an annular structure inner wall includes: A rotary table is used to clamp the ring-shaped structure to be added and drive the ring-shaped structure to rotate. The stirring head is fixedly connected to the main shaft and includes an upper screw section. The bottom end of the upper screw section is connected to a stirring needle. The filament is cut in the upper screw section and sent to the stirring needle. The filament is broken by friction and shearing through the stirring needle. The sleeve is fixedly connected to the main shaft housing and is fitted onto the stirring head. The sleeve is provided with a wire feeding hole, through which the wire is fed to the upper screw section. The bottom of the sleeve has an opening on one side, allowing the stirring needle to be exposed. An ultrasonic tool head, the front end of which contacts the stirring head via a bearing to transmit ultrasonic vibrations.

[0009] As a further implementation, the stirring head also includes a smooth rod section, with an upper screw section connected to the bottom end of the smooth rod section and fixedly connected to the main shaft through the smooth rod section; The outer diameter of the stirring pin is smaller than the outer diameter of the upper screw section, so as to form an inner shoulder at the bottom end of the upper screw section. The radius difference between the stirring pin and the upper screw section is adapted to the thickness of the single-layer additive layer.

[0010] As a further implementation, the sleeve is connected to the wire feeding system through a wire feeding hole, the position of which corresponds to the top end of the upper screw section; The stirring head rotates clockwise, and the thread on the upper screw section is a left-hand thread.

[0011] As a further implementation, the height of the opening is adapted to the height of the stirring needle, and an upper shoulder is formed at the top of the opening, and a lower shoulder is formed at the bottom of the sleeve. The lower surface of the upper shoulder is designed to be flush with the upper surface of the annular structure or the single-layer additive layer, such that the outer wall of the lower shoulder is tangent to the inner wall of the annular structure or the single-layer additive layer.

[0012] As a further implementation, the surface of the stirring pin is provided with cross-threaded grooves, or... The surface of the stirring needle is threaded, and the direction of the thread is opposite to that of the thread on the upper screw section.

[0013] As a further implementation, the height of the opening is adapted to the height of the stirring needle, and an upper shoulder is formed at the top of the opening through the opening. The bottom end of the sleeve is open, and the surface of the stirring needle is provided with a cross-threaded groove. The bottom end of the stirring needle is connected to the lower screw section, the outer diameter of the lower screw section is the same as the outer diameter of the upper screw section, and a shoulder of the lower screw section is formed at the top of the lower screw section, the shoulder of the lower screw section corresponds to the position of the bottom end of the sleeve.

[0014] As a further implementation, the lower surface of the upper shoulder is used to be flush with the upper surface of the annular structure or the single-layer additive layer, so that the outer wall of the lower screw section shoulder is tangent to the inner wall of the annular structure or the single-layer additive layer. The threads on the lower screw section and the threads on the upper screw section have opposite directions of rotation.

[0015] As a further implementation, the ultrasonic tool head is positioned perpendicular to the stirring head; The ultrasonic tool head is mounted on the spindle housing via a bracket and can move horizontally. The main body of the ultrasonic tool head is an amplitude transformer, and the front end of the amplitude transformer is provided with at least two sets of cylindrical roller bearings, which are in tangential contact with the smooth rod section of the stirring head.

[0016] As a further implementation, the rotary table is mounted on a workbench, and the rotary table is equipped with a radially adjustable centering chuck for clamping the annular structure. Secondly, an ultrasonic stirring friction solid-phase additive manufacturing method for the inner wall of an annular structure, employing any of the additive manufacturing apparatuses described above, includes the following steps: Fix the ring structure on the worktable, then move the worktable so that the inner wall of the ring structure is close to the exposed part of the stirring head; Move the spindle so that the lower surface of the upper shoulder of the sleeve is flush with the upper surface of the annular structure, ensuring that the outer wall of the lower shoulder of the sleeve is tangent to the inner wall of the annular structure. The stirring head rotates clockwise, and the two bearings at the front end of the ultrasonic tool head contact the side of the stirring head; Start the ultrasonic generator, and the ultrasonic vibration is vertically introduced into the stirring head through the ultrasonic tool head. Start the wire feeder to feed the wire into the wire feeding hole. The filament reaches the upper screw section through the filament feeding hole. The filament is cut by the left-hand thread. With the cooperation of the thread direction and the rotation direction of the stirring head, the broken filament is fed into the stirring needle. The stirring needle frictionally shears the broken filament, and plastic flow occurs together with the material on the inner wall of the annular structure. It is deposited under the rotation of the stirring head. Under the constraint of the shoulder on the sleeve and the wall of the stirring needle, the plasticized material is compacted and forms a dense single-layer additive layer. After completing a full circle of single-layer additive manufacturing, the worktable is moved horizontally and the above process is repeated to deposit multiple layers of additive manufacturing on the already deposited layer.

[0017] The beneficial effects of the present invention are as follows: 1. This invention, by incorporating a stirring head, an ultrasonic tool head, and a sleeve, allows the plasticized material to gradually deposit on the inner wall of the ring structure as it rotates within the stationary sleeve, achieving layer-by-layer deposition and ultimately forming a multi-layer additive layer. Introducing ultrasonic vibration perpendicular to the stirring head significantly promotes the plastic flow and filling of the material, resulting in a denser and more uniform additive layer structure and improved forming quality. Simultaneously, ultrasound further refines the grains and breaks down IMCs, enhancing both formability and the overall mechanical properties of the additive interface.

[0018] 2. This invention employs a solid-state additive manufacturing method, whose low heat input effectively reduces the overall deformation and residual stress of the ring structure during the additive manufacturing process. Especially in the fabrication of dissimilar metal transition layers, the low heat input can suppress the growth of IMCs, thereby ensuring the mechanical properties of the additive interface.

[0019] 3. This invention can be achieved by modularizing existing gantry-type friction stir welding equipment, without the need to develop entirely new equipment. Specifically, it only requires adding a rotary table to the workbench for fixing the ring-shaped workpiece, integrating an ultrasonic system on the main shaft, and adding a wire feeder. The modification cost is low and the cycle is short, which is very conducive to the rapid promotion and application of this technology in the industrial field.

[0020] 4. This invention uses filament as raw material, offering high flexibility in material design and processing. By selecting filaments with different compositions, the alloy composition of the additive layer can be flexibly controlled. This not only enables dimensional repair and performance enhancement of the same metal but also facilitates the preparation of transition layers between dissimilar metals, and even provides a feasible technical path for the future development of multi-material hybrid additive manufacturing. Furthermore, increasing the number of wire feeding holes and filaments can significantly improve additive manufacturing efficiency. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the ultrasonic stirring friction solid-phase additive manufacturing apparatus in an embodiment of the present invention; Figure 2 This is a top view of the ultrasonic stirring friction solid-phase additive manufacturing apparatus in an embodiment of the present invention; Figure 3 yes Figure 2 Sectional view of section AA; Figure 4 This is a process flow diagram of the additive manufacturing method in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the ultrasonic tool head in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the sleeve and stirring head in an embodiment of the present invention; Figure 7 This is a schematic diagram of the sleeve and stirring head in another example of the present invention; Figure 8 This is a schematic diagram of the sleeve and stirring head in another example of the present invention.

[0023] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0024] Among them: 1. Worktable, 2. Rotary table, 3. Ring structure, 4. Ultrasonic tool head, 4-1. Amplitude rod, 4-2. Bearing, 5. Wire, 6. Sleeve, 6-1. Wire feeding hole, 6-2. Upper shoulder, 6-3. Lower shoulder, 7. Stirring head, 7-1. Upper screw section, 7-2. Inner shoulder, 7-3. Stirring needle, 7-4. Lower screw section shoulder, 7-5. Lower screw section, 8. Single-layer additive layer, 9. Multi-layer additive layer. Detailed Implementation

[0025] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] Example 1 In a typical embodiment of the present invention, reference is made to Figures 1-6 As shown, an ultrasonic friction stir solid-phase additive manufacturing apparatus with an annular inner wall includes a worktable 1, a rotary table 2, an ultrasonic tool head 4, a sleeve 6, a stirring head 7, and a wire feeding system. This apparatus is modified from a gantry-type friction stir welding machine. The worktable 1 of the welding machine can move horizontally left and right, and its displacement accuracy is precisely controlled by a lead screw drive.

[0027] The stirring head 7 is fixedly connected to the spindle and includes an upper screw section 7-1. A stirring needle 7-3 is connected to the bottom end of the upper screw section 7-1. The wire 5 is cut at the upper screw section 7-1 and fed to the stirring needle 7-3, where it is sheared and broken by friction. A sleeve is fixedly connected to the spindle housing and fits onto the stirring head. The sleeve has a wire feeding hole through which the wire is fed to the upper screw section. An opening on one side of the bottom end of the sleeve exposes the stirring needle. The front end of the ultrasonic tool head contacts the stirring head via a bearing to transmit ultrasonic vibrations.

[0028] like Figure 1 As shown, the rotary table 2 is used to clamp the annular structure 3 to be added and drive the annular structure 3 to rotate. It is fixed to the upper surface of the worktable 1 by bolts. The rotary table 2 is equipped with a radially adjustable centering chuck. Six guide rails are evenly distributed along the circumference on the centering chuck. Each guide rail is equipped with a positioning block. By synchronously adjusting the position of all positioning blocks, annular structures 3 of different diameters can be clamped and their centers can be strictly coincided with the rotation center of the rotary table 2.

[0029] In this embodiment, the annular structure 3 is a machined ring with an outer diameter of 450 mm, an inner diameter of 350 mm, and a height of 100 mm.

[0030] like Figure 3 and Figure 6 As shown, the stirring head 7 is made of tool steel and includes, from top to bottom, a smooth rod section, an upper screw section 7-1, an inner shoulder 7-2, and a stirring needle 7-3 connected in sequence. The stirring head 7 is fixedly connected to the main shaft through the smooth rod section, so that the main shaft can drive the stirring head 7 to rotate.

[0031] In an optional example, the spindle drives the stirring head 7 to rotate clockwise, and the thread on the upper screw section 7-1 is a left-hand thread. The thread direction of the upper screw section 7-1 needs to match the rotation direction of the stirring head 7. When the upper screw section 7-1 is a right-hand thread, the stirring head rotates counterclockwise. The rotation direction of the stirring head 7 needs to be the same as the rotation direction of the rotating table 2.

[0032] like Figure 6 As shown, the outer diameter of the stirring pin 7-3 is smaller than the outer diameter of the upper screw section 7-1, thus forming a stepped structure at the bottom end of the upper screw section 7-1, called the inner shoulder 7-2. The radius difference between the stirring pin 7-3 and the upper screw section 7-1 is matched with the thickness of the single-layer additive layer 8, allowing the filament to be deposited on the outside of the exposed part of the stirring pin.

[0033] The left-hand thread of the upper screw section 7-1 has a threaded groove structure. In one optional example, the cross-section of the threaded groove is an isosceles trapezoid. This shape is easy to machine and, due to the greater thickness at the tooth root, it is less likely to break when pushing material. The height of the trapezoid is 6mm, the base of the trapezoid near the tooth root is 8mm, and the base away from the tooth root is 12mm. In other examples, the cross-section can also be rectangular.

[0034] The outer diameter of the upper screw section 7-1 is the same as the outer diameter of the inner shoulder 7-2, which is 40mm. It is used to cut the filament 5 and convey it downward to the stirring needle 7-3. The bottom surface of the inner shoulder 7-2 restricts the filament 5 at the stirring needle 7-3, which facilitates the deposition of the filament 5.

[0035] Understandably, the main body of the stirring needle 7-3 is cylindrical with an outer diameter of 36 mm and a length of 40 mm. Its surface is machined with cross-threaded grooves, which enhance the ability to crush and convey wire.

[0036] The cross-threaded groove is formed by multiple left-handed threads and multiple right-handed threads crossing each other. In an optional example, the depth of the cross-threaded groove is 0.5 mm, and the axial spacing between parallel threads of the same direction is 10 mm.

[0037] like Figure 3 and Figure 6 As shown, the sleeve 6 is also made of tool steel. The sleeve 6 is used to fit onto the stirring head 7, and the internal space of the sleeve 6 is adapted to the outer diameter of the stirring head 7. During operation, the sleeve 6 is fixedly connected to the main shaft housing and remains stationary, while the stirring head 7 can rotate inside the sleeve 6.

[0038] The top of the sleeve 6 is open so that it can be fitted onto the stirring head 7 from bottom to top. The bottom of the sleeve 6 is closed by the base plate. However, in order to allow the wire 5 to be piled up inside the annular structure 3, an opening needs to be provided on one side of the bottom of the sleeve so that the side of the stirring needle can be exposed. During the processing, the exposed part of the stirring needle 7-3 needs to be close to the inside of the annular structure 3.

[0039] The sleeve 6 has an opening on one side at the bottom end, that is, a notch is made on the side wall of the sleeve 6. The projection shape of the notch is rectangular, and the bottom end of the notch extends to the bottom plate of the sleeve. The sleeve 6 forms an upper shoulder 6-2 at the top of the opening through the opening, and a lower shoulder 6-3 is formed at the edge of the bottom plate of the sleeve.

[0040] like Figure 3 As shown, the height of the opening of the sleeve 6 is adapted to the height of the stirring needle 7-3, while the height of the upper shoulder 6-2 corresponds to the height of the inner shoulder 7-2, so that the entire stirring needle 7-3 is exposed on the side near the opening.

[0041] The sleeve 6 is also provided with a wire feeding hole 6-1. The position of the wire feeding hole 6-1 corresponds to the top position of the upper screw section 7-1. The sleeve 6 is connected to the wire feeding system through the wire feeding hole 6-1. The wire feeding system feeds the wire 5 into the wire feeding hole 6-1 so that the wire 5 reaches the top position of the upper screw section 7-1.

[0042] In an optional example, a 4 mm diameter wire 5 is used, and the wire feed hole 6-1 has a 5 mm diameter.

[0043] It is understandable that there may be one or more wire feeding holes 6-1, and similarly, the wire may be one or more.

[0044] In one optional example, the outer diameter of the upper shoulder 6-2 is 50 mm, and the outer diameter of the lower shoulder 6-3 is 40 mm. The outer diameter of the lower shoulder 6-3 is the same as the outer diameter of the upper screw section 7-1. The inner diameter of the upper shoulder 6-2 is adapted to the outer diameter of the upper screw section 7-1.

[0045] Understandably, the difference between the radius of the lower shoulder 6-3 and the radius of the stirring needle 7-3 is 2 mm, and this difference is designed to be equal to the thickness of the single-layer additive layer 8. For example... Figure 3 As shown, during processing, the lower surface of the upper shoulder 6-2 is flush with the upper surface of the annular structure or the single-layer additive layer, so that the outer wall of the lower shoulder 6-3 is tangent to the inner wall of the annular structure or the single-layer additive layer 8. At this time, the minimum distance from the outer side of the stirring needle 7-3 to the inner side of the annular structure or the inner side of the single-layer additive layer is 2mm, which is equal to the thickness of the single-layer additive layer 8, making it easier for the filament to accumulate on the exposed part of the stirring needle 7-3.

[0046] like Figure 5 The diagram shows the structure of the ultrasonic tool head 4. During processing, the ultrasonic tool head 4 is mounted on the spindle housing via a bracket. Specifically, the ultrasonic tool head 4 is mounted on a horizontal guide rail on the bracket. The bracket is also equipped with a pneumatic drive unit. The ultrasonic tool head 4 is connected to the output end of the pneumatic drive unit, which can drive the ultrasonic tool head 4 to move horizontally.

[0047] The main body of the ultrasonic tool head 4 is an amplitude transformer 4-1. At least two sets of freely rotatable bearings 4-2 are provided at the front end of the amplitude transformer 4-1. The bearings 4-2 are cylindrical roller bearings (two sets in this embodiment). The ultrasonic tool head 4 should be set perpendicular to the stirring head 7 and make tangential contact with the smooth rod section of the stirring head 7 through the bearings 4-2.

[0048] Bearing 4-2 serves as a vibration transmission and support component. Bearing 4-2 has a diameter of 15 mm and a height of 10 mm. During additive manufacturing, the pneumatic drive unit applies pressure to the end of the ultrasonic tool head 4, pushing it to move horizontally along the guide rail. Using the pneumatic drive unit to control the feed of the ultrasonic tool head 4 ensures that the outer rings of the two bearings 4-2 maintain tangential contact with the side of the rotating stirring head 7, and maintains a constant contact pressure between the bearings 4-2 and the side of the stirring head 7. This allows ultrasound to be transmitted vertically to the stirring head 7 without significantly hindering its rotation.

[0049] The preferred ultrasonic vibration frequency is 20-30 kHz, the preferred amplitude is 5-50 μm, and the preferred contact force is around 300 N.

[0050] In this embodiment, by setting up a stirring head 7, an ultrasonic tool head 4, and a sleeve 6, the plasticizing material can be gradually deposited on the inner wall of the ring structure 3 as the ring structure rotates, achieving layer-by-layer deposition and finally forming a multi-layer additive layer 9.

[0051] Example 2 This embodiment discloses an ultrasonic stirring friction solid-phase additive manufacturing method for the inner wall of an annular structure. The device size is the same as in Embodiment 1, except that this device is used to deposit an aluminum alloy additive layer of the same composition on the inner wall of a 6061 aluminum alloy annular structure, such as... Figure 4 As shown, the main steps include: Step 1: Install the 6061 aluminum alloy ring structure 3 onto the rotary table 2, and clean and polish the inner wall to remove oil and oxide film.

[0052] Step 2: Install the stirring head 7 on the main shaft, put the sleeve 6 around the stirring head 7, and fix the sleeve 6 on the main shaft housing so that the sleeve 6 does not rotate with the main shaft during the additive manufacturing process.

[0053] Step 3: Adjust the equipment. Move the worktable 1 horizontally so that the inner wall of the annular structure 3 is close to the stirring head 7. Move the main shaft vertically so that the lower surface of the upper shoulder 6-2 of the sleeve 6 is flush with the upper surface of the annular structure 3, while ensuring that the outer wall of the lower shoulder 6-3 of the sleeve 6 is tangent to the inner wall of the annular structure 3.

[0054] Step 4: Start the spindle and rotate the stirring head 7 clockwise at 1000 rpm. Then move the ultrasonic tool head 4 horizontally so that the two bearings 4-2 at its front end contact the side of the stirring head 7 and maintain a contact force of about 300 N. Under the action of friction, the bearings 4-2 rotate synchronously with the stirring head 7, maintaining the same linear velocity as the side of the stirring head 7 at the tangent point.

[0055] Step 5: Start the ultrasonic generator. The ultrasonic vibration is vertically introduced into the stirring head 7 through the amplitude transformer 4-1 and bearing 4-2. The ultrasonic frequency used is 20 kHz, and the output amplitude is 20 μm. At the same time, start the wire feeder to feed the Al-Mg-Si aluminum alloy wire 5 into the wire feeding hole 6-1 of the sleeve 6 at a speed of 5 m / min. Since the wire feeding volume per unit time must be equal to the deposition volume per unit time, the rotation speed of the rotary table 2 driving the annular structure 3 to rotate synchronously is calculated to be 0.71 rpm. In order to ensure that the additive layer is dense enough, the rotation speed of the rotary table 2 needs to be slightly reduced to ensure sufficient feeding. Therefore, the final rotation speed of the rotary table 2 is set to 0.7 rpm.

[0056] Step 6: After the filament 5 enters the upper screw section 7-1 of the stirring head 7 through the filament feeding hole 6-1, the left-hand thread above it cuts the filament 5. With the cooperation of the thread direction and the rotation direction of the stirring head 7, the broken filament 5 is fed into the stirring needle 7-3. Under the frictional shearing action of the cross-threaded grooves on the surface of the stirring needle 7-3, it undergoes plastic flow together with the surface material of the inner wall of the annular structure 3, and begins to deposit under the rotation of the stirring head 7. Under the constraint of the inner shoulder 7-2, the outer surface of the stirring needle 7-3, the sleeve 6, and the lower shoulder 6-3, the plasticized material is compacted and forms a dense single-layer additive layer 8.

[0057] Step 7: After completing one full rotation of single-layer additive manufacturing, the stirring head 7 and ultrasonic tool head 4 remain in the same position and with the same parameters. The worktable 1 is precisely moved 2 mm (i.e., the thickness of the single-layer additive layer 8) horizontally away from the stirring head 7. The above wire feeding, rotation, and ultrasonic application process is repeated to deposit multiple layers of additive layers 9 on the already deposited layer. As the number of additive layers increases, the volume of each layer gradually decreases due to the reduction in the radius of the additive layers. It is necessary to gradually increase the rotation speed of the rotary table 2 to match the constant wire feeding speed or decrease the wire feeding speed to match the constant rotation speed of the rotary table 2.

[0058] Example 3 This embodiment discloses an ultrasonic stirring friction solid-phase additive manufacturing method for preparing an aluminum alloy transition layer on the inner wall of a steel ring structure. The device dimensions are the same as in Embodiment 1, except that the ring structure 3 is made of 42CrMo high-strength alloy steel, and the aluminum alloy wire composition is Al-Mg. The stirring head 7 is made of tungsten-rhenium alloy to withstand the high temperatures that may be generated by friction near the steel substrate, and the sleeve 6 is made of tool steel. The implementation steps are basically the same as in Embodiment 2, with the following differences: To avoid excessively thick IMCs on the interface due to high heat input, the stirring head 7 speed is set to 600 rpm to reduce heat input.

[0059] To overcome the difficulty of achieving metallurgical bonding between dissimilar metals in solid-state additive manufacturing, the inner wall of the annular structure 3 needs to be strictly sandblasted before additive manufacturing to thoroughly remove oxide scale and increase surface roughness, thereby promoting the interfacial mechanical interlocking and plastic flow bonding of aluminum / steel dissimilar materials.

[0060] Example 4 This embodiment discloses an ultrasonic stirring friction solid-phase additive manufacturing method for repairing the worn area of ​​the inner wall of a steel ring structure 3. The device size is the same as that in Embodiment 1. The difference is that the ring structure 3 is made of GCr15 bearing steel, and the wire material is also made of GCr15 to ensure metallurgical bonding with the steel matrix. The stirring head 7 is made of polycrystalline cubic boron nitride (PCBN), and the sleeve 6 is made of tungsten rhenium alloy 6 to withstand the high temperature generated during steel additive manufacturing.

[0061] The implementation steps are basically the same as in Example 2, except that: A rotation speed of 600 rpm is used to reduce heat input and avoid degradation of the mechanical properties of the stirring head 7 due to high temperature.

[0062] During the additive repair process, liquid nitrogen needs to be continuously sprayed onto the additive layer behind the stirring head 7 for cooling, in order to prevent the PCBN stirring head from overheating and failing, and to reduce the width of the heat-affected zone caused by solid-phase additive manufacturing.

[0063] After additive manufacturing is completed, the mixing head 7 needs to be replaced with a milling cutter to perform precision milling on the additive area to remove excess additive material and ensure that the inner diameter of the component meets the final dimensional accuracy and surface finish requirements of the design.

[0064] Example 5 This embodiment discloses an ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure. For example... Figure 7 As shown, the structure of the stirring head 7 in this embodiment is different from that in embodiment 1, but the other structures are the same.

[0065] The difference between the stirring head 7 in this embodiment and that in embodiment 1 is that the cross-threaded groove structure on the surface of the stirring pin 7-3 is replaced with a thread that has the opposite direction of the thread on the upper screw section 7-1, i.e., a right-hand thread.

[0066] As the stirring head 7 rotates clockwise, the left-hand thread of the upper screw section 7-1 exerts a downward force on the material, causing it to move downwards and enter the stirring pin 7-3 section. Because the stirring pin 7-3 has a right-hand thread, the material experiences an upward force within this section. However, since the upward driving force provided by the threads of the stirring pin 7-3 is limited, the material eventually accumulates at the intersection of the stirring pin 7-3 and the upper screw section 7-1, specifically below the inner shoulder 7-2, and is deposited from top to bottom. This structure helps increase the density of the final deposited material.

[0067] Example 6 This embodiment discloses an ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure. For example... Figure 8 As shown, unlike Example 1, the bottom end of the stirring needle 7-3 is connected to the lower screw section 7-5. The shape and size of the lower screw section 7-5 are completely the same as those of the upper screw section 7-1, but its thread direction is right-handed, and a lower screw section shoulder 7-4 is formed at the top of the lower screw section.

[0068] Furthermore, to accommodate the lower screw section 7-5, the bottom end of the sleeve 6 is open, meaning the sleeve 6 does not have a bottom plate and does not contain a lower shoulder 7-3. Because the stirring head 7 rotates clockwise, the right-hand thread of the lower screw section 7-5 exerts an upward force on the material, causing it to move upwards. Therefore, the material is confined at the stirring pin 7-3 by the upper shoulder 7-2 and the lower screw section shoulder 7-4. When the material at the stirring pin 7-3 exceeds the maximum volume that can be accommodated by the side wall of the stirring pin 7-3, the inner wall of the sleeve 6, the inner wall of the annular structure 3, or the inner surface of the additive layer 8, the confinement of the material by the lower screw section 7-5 is weaker than that of the sleeve 6 containing the lower shoulder 6-3, thus allowing the material to overflow downwards. This structure helps prevent material blockage during deposition.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ultrasonic stirring friction solid-phase additive manufacturing apparatus for an annular inner wall, characterized in that, include: A rotary table is used to hold the ring-shaped structure to be added and to drive the ring-shaped structure to rotate. The stirring head is fixedly connected to the main shaft and includes an upper screw section. The bottom end of the upper screw section is connected to a stirring needle. The filament is cut in the upper screw section and sent to the stirring needle. The filament is broken by friction and shearing through the stirring needle. The sleeve is fixedly connected to the main shaft housing and is fitted onto the stirring head. The sleeve is provided with a wire feeding hole, through which the wire is fed to the upper screw section. The bottom of the sleeve has an opening on one side, allowing the stirring needle to be exposed. An ultrasonic tool head, the front end of which contacts the stirring head via a bearing to transmit ultrasonic vibrations.

2. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 1, characterized in that, The stirring head also includes a smooth rod section, and an upper screw section is connected to the bottom end of the smooth rod section and is fixedly connected to the main shaft through the smooth rod section; The outer diameter of the stirring pin is smaller than the outer diameter of the upper screw section, so as to form an inner shoulder at the bottom end of the upper screw section. The radius difference between the stirring pin and the upper screw section is adapted to the thickness of the single-layer additive layer.

3. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 2, characterized in that, The sleeve is connected to the wire feeding system through a wire feeding hole, the position of which corresponds to the top end of the upper screw section. The stirring head rotates clockwise, and the thread on the upper screw section is a left-hand thread.

4. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 3, characterized in that, The height of the opening is adapted to the height of the stirring needle, and an upper shoulder is formed at the top of the opening, while a lower shoulder is formed at the bottom of the sleeve. The lower surface of the upper shoulder is designed to be flush with the upper surface of the annular structure or the single-layer additive layer, such that the outer wall of the lower shoulder is tangent to the inner wall of the annular structure or the single-layer additive layer.

5. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 4, characterized in that, The surface of the stirring pin is provided with cross-threaded grooves, or... The surface of the stirring needle is threaded, and the direction of the thread is opposite to that of the thread on the upper screw section.

6. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 3, characterized in that, The height of the opening is adapted to the height of the stirring needle, and an upper shoulder is formed at the top of the opening through the opening. The bottom end of the sleeve is open, and the surface of the stirring needle is provided with a cross-threaded groove. The bottom end of the stirring needle is connected to the lower screw section, the outer diameter of the lower screw section is the same as the outer diameter of the upper screw section, and a shoulder of the lower screw section is formed at the top of the lower screw section, the shoulder of the lower screw section corresponds to the position of the bottom end of the sleeve.

7. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 6, characterized in that, The lower surface of the upper shoulder is used to be flush with the upper surface of the annular structure or the single-layer additive layer, so that the outer wall of the lower screw section shoulder is tangent to the inner wall of the annular structure or the single-layer additive layer. The threads on the lower screw section and the threads on the upper screw section have opposite directions of rotation.

8. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 2, characterized in that, The ultrasonic tool head is positioned perpendicularly to the stirring head; The ultrasonic tool head is mounted on the spindle housing via a bracket and can move horizontally. The main body of the ultrasonic tool head is an amplitude transformer, and the front end of the amplitude transformer is provided with at least two sets of cylindrical roller bearings, which are in tangential contact with the smooth rod section of the stirring head.

9. The ultrasonic stirring friction solid-phase additive manufacturing apparatus for the inner wall of an annular structure according to claim 1, characterized in that, The rotary table is mounted on the workbench, and the rotary table is equipped with a radially adjustable centering chuck for clamping the annular structure.

10. A method for ultrasonic stirring friction solid-phase additive manufacturing of the inner wall of an annular structure, characterized in that, The additive manufacturing apparatus as described in any one of claims 1-9 includes the following steps: Fix the ring structure on the worktable, then move the worktable so that the inner wall of the ring structure is close to the exposed part of the stirring head; Move the spindle so that the lower surface of the upper shoulder of the sleeve is flush with the upper surface of the annular structure, ensuring that the outer wall of the lower shoulder of the sleeve is tangent to the inner wall of the annular structure. The stirring head rotates clockwise, and the two bearings at the front end of the ultrasonic tool head contact the side of the stirring head; Start the ultrasonic generator, and the ultrasonic vibration is vertically introduced into the stirring head through the ultrasonic tool head. Start the wire feeder to feed the wire into the wire feeding hole. The filament reaches the upper screw section through the filament feeding hole. The filament is cut by the left-hand thread. With the cooperation of the thread direction and the rotation direction of the stirring head, the broken filament is fed into the stirring needle. The stirring needle frictionally shears the broken filament, and plastic flow occurs together with the material on the inner wall of the annular structure. It is deposited under the rotation of the stirring head. Under the constraint of the shoulder on the sleeve and the wall of the stirring needle, the plasticized material is compacted and forms a dense single-layer additive layer. After completing a full circle of single-layer additive manufacturing, the worktable is moved horizontally and the above process is repeated to deposit multiple layers of additive manufacturing on the already deposited layer.

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