Friction stir deposition method and friction rolling deposition forming device

Abstract

The invention discloses a friction stir deposition method and a friction rolling deposition forming device. The friction stir deposition method comprises the step of rolling a deposition layer formed by friction stir deposition. The friction rolling deposition forming device comprises friction stir deposition equipment and rolling equipment, the rolling equipment comprises a rolling wheel, and after a deposition layer is formed through friction stir deposition, the rolling wheel can roll the deposition layer. Through rolling, the deposition layer generates severe plastic deformation and induces dynamic recrystallization, the grain refining effect is achieved, meanwhile, replastic flowing at the interface of the deposition layer and the substrate is promoted, and the interface bonding strength of the deposition layer and the substrate is remarkably improved; the friction contact between the tool head and the deposited workpiece can be weakened, the tool head is prevented from being abraded, and the service life of the tool is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a stirring friction deposition method and a friction roller deposition forming apparatus. Background Technology

[0002] Aluminum alloys possess advantages such as high specific strength and good corrosion resistance, making them widely used in the rail transportation field. However, under actual service conditions, aluminum alloy components are prone to wear due to insufficient wear resistance, which can severely affect the operational stability and safety of the components. Therefore, preparing wear-resistant coatings on the surface of aluminum alloys is of great significance for improving the service life of aluminum alloy components.

[0003] Preparing a wear-resistant layer containing ceramic particles on the surface of aluminum alloys can maintain the toughness of the aluminum alloy substrate while improving the surface wear resistance. Existing surface coating preparation technologies include cold spraying and laser cladding. Among them, cold spraying is difficult to achieve a strong metallurgical bond between the coating and the substrate, resulting in low interfacial bonding strength; although melting processing methods such as laser cladding can achieve a metallurgical bond between the coating and the substrate, the high processing temperature and large heat input will significantly increase the temperature gradient between the coating and the substrate, easily generating large residual stress and cracking tendency.

[0004] High-quality wear-resistant composites can also be fabricated on aluminum alloy substrates using friction stir deposition (FSD). The forming principle involves a composite metal rod passing through a hollow stirring head under extrusion pressure, rubbing against the substrate. The high-speed rotation of the stirring head provides downward pressure and shearing action, causing the composite metal rod to flow in a plasticized state and form a deposited layer. However, poor bonding quality may exist between the wear-resistant deposited layer and the aluminum alloy substrate, leading to reduced shear strength of the component and easy peeling of the wear-resistant layer during service. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a stirring friction deposition method.

[0006] Another object of the present invention is to provide a friction roll deposition forming apparatus for implementing the above-described friction stir deposition method.

[0007] Another object of the present invention is to provide the use of the above-described friction stir deposition method in improving shear strength or plasticity in friction stir deposition.

[0008] Another object of the present invention is to provide the use of the above-described friction roll deposition forming apparatus for improving shear strength or plasticity in friction stir deposition.

[0009] The objective of this invention is achieved through the following technical solutions.

[0010] A method for friction stirring deposition includes: rolling the deposited layer formed by friction stirring deposition.

[0011] In the above technical solution, the rolling is performed within 8 to 12 seconds after the deposition layer is formed.

[0012] In the above technical solution, the pressure for rolling the deposited layer is 60-100kN.

[0013] A friction roller deposition forming apparatus for realizing the friction stir deposition method includes: a friction stir deposition device and a roller pressing device. The roller pressing device is located on one side of the friction stir deposition device. Both the roller pressing device and the friction stir deposition device are fixed on a mounting base. With the travel direction of the friction stir deposition device as the front, the roller pressing device is located behind the friction stir deposition device. The roller pressing device includes: a rod and a roller pressing wheel. The rod is vertically arranged, and the roller pressing wheel is rotatably installed at the bottom end of the rod.

[0014] In the above technical solution, a bearing is installed between the roller and the rod.

[0015] In the above technical solution, the rod can move along its length.

[0016] In the above technical solution, the roller pressing equipment further includes a linear motion mechanism for driving the rod to move along its length direction.

[0017] In the above technical solution, the linear motion mechanism includes: a hydraulic cylinder, a ball screw, or a rack.

[0018] In the above technical solution, when the linear motion mechanism includes a ball screw, the rolling equipment further includes: a motor for driving the ball screw to move, the nut of the ball screw being fixedly mounted to the mounting base, the screw of the ball screw being vertically arranged, the screw being fixedly mounted to the rod body for driving the rod body to move, or the bottom of the screw serving as the rod body.

[0019] In the above technical solution, the motor directly or indirectly drives the ball screw. When the motor directly drives the ball screw, the motor output shaft is fixed to the screw. When the motor indirectly drives the ball screw, the motor output shaft and the screw are transmitted through a synchronous belt pulley set.

[0020] In the above technical solution, the synchronous pulley assembly includes: a driving synchronous pulley, a driven synchronous pulley, and a synchronous belt. The motor drives the driving synchronous pulley to rotate, the driven synchronous pulley is fixedly mounted to the screw, and the synchronous belt is sleeved on the driving synchronous pulley and the driven synchronous pulley.

[0021] In the above technical solution, the roller is made of cemented carbide and the diameter of the roller is 40-100 mm.

[0022] In the above technical solution, the friction roller deposition forming device further includes: a force sensor, used to detect in real time the pressure applied by the roller to the deposition layer.

[0023] The above-mentioned friction stir deposition method is used to improve shear strength or plasticity in friction stir deposition.

[0024] The above-mentioned friction roller deposition forming apparatus is used to improve shear strength or plasticity in stirred friction deposition.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The friction roller deposition forming apparatus of the present invention is equipped with a roller pressing device, which provides pressure through the roller pressing wheel to cause the deposition layer to undergo severe plastic deformation, thereby inducing dynamic recrystallization and achieving the effect of refining the grains;

[0027] 2. During the rolling process, the replastic flow at the interface between the deposited layer and the substrate enhances the mechanical and metallurgical bond between the substrate and the deposited layer, significantly improving the interfacial bonding strength between the deposited layer and the substrate.

[0028] 3. In this invention, when using roller pressing for strengthening, the deposition rate and feeding rate of the friction stir deposition equipment can be increased. The main function of the tool head is no longer to provide friction and downward pressure, but rather to provide a discharge port. The forging pressure is mainly provided by the roller pressing roller. The roller pressing process can reduce the frictional contact between the tool head and the deposited workpiece, avoid tool head wear, and extend tool life. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the friction roller deposition forming apparatus in Embodiment 3 of the present invention;

[0030] Figure 2 This is a cross-sectional view of the agitation and friction deposition apparatus in Embodiment 3 of the present invention;

[0031] Figure 3 (a) shows the interface bonding state of the stir-friction deposition method of Example 5 of the present invention, and (b) shows the interface bonding state of the stir-friction deposition method of Comparative Example 1 of the present invention.

[0032] Figure 4 (a) is a comparison diagram of shear stress-strain of the deposited parts in Example 5 and Comparative Example 1 of the present invention, and (b) is a comparison diagram of macroscopic and microscopic shear fracture surfaces of the deposited parts in Example 5 and Comparative Example 1 of the present invention.

[0033] Wherein, 1: mounting base, 2: substrate, 3: friction stir deposition equipment, 3-1: rotating shaft, 3-2: push rod, 3-3: tool holder, 3-4: shoulder, 3-5: bar stock, 3-6: housing, 4: rolling equipment, 4-1-1: screw, 4-1-2: nut, 4-2: rolling roller, 4-3: motor, 4-4: reducer, 4-5: synchronous belt pulley set, 5: deposition layer. Detailed Implementation

[0034] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] A method for friction stirring deposition includes: rolling a deposition layer 5 formed by friction stirring deposition, wherein the rolling is performed within 8 to 12 seconds after the deposition layer 5 is formed, and the pressure for rolling the deposition layer is 60 to 100 kN.

[0037] In this embodiment, rolling causes severe plastic deformation of the deposited layer 5, inducing dynamic recrystallization and refining the microstructure of the deposited layer 5. Simultaneously, during rolling, the replastic flow at the interface between the deposited layer 5 and the substrate 2 enhances the mechanometallic bond between the substrate 2 and the deposited layer 5, significantly improving the shear bond strength between the deposited layer 5 and the substrate 2. When using rolling for strengthening, the deposition rate and feed rate of the friction stir deposition apparatus 3 can be increased. The primary function of the tool head is no longer to provide friction and downward pressure, but rather to provide a discharge port. The forging pressure is mainly provided by the rolling rollers 4-2. The rolling process reduces the frictional contact between the tool head and the deposited workpiece, preventing tool head wear and extending tool life.

[0038] Example 2

[0039] A friction roller deposition forming apparatus for implementing the friction stir deposition method in Embodiment 1 includes: a friction stir deposition device 3 and a roller pressing device 4. The roller pressing device 4 is located on one side of the friction stir deposition device 3. Both the roller pressing device 4 and the friction stir deposition device 3 are fixedly mounted on a mounting base 1. With the travel direction of the friction stir deposition device 3 as the front, the roller pressing device 4 is located behind the friction stir deposition device 3. The roller pressing device 4 includes: a rod and a roller pressing wheel 4-2. The rod is vertically arranged, and the roller pressing wheel 4-2 is rotatably mounted on the bottom end of the rod. A bearing is installed between the roller pressing wheel 4-2 and the rod, and the rod can move along its length.

[0040] The working process of the above-mentioned friction roller deposition forming apparatus includes: performing friction stirring deposition (FSD) on the substrate 2 using the friction stirring deposition equipment 3 to form a deposition layer 5; moving the rod downwards so that the roller 4-2 can press onto the deposition layer 5; as the friction stirring deposition equipment 3 moves forward, the roller 4-2 passes over the newly formed deposition layer 5, applying pressure to the deposition layer 5 as it passes. The pressure applied by the roller 4-2 to the deposition layer 5 can be adjusted by the moving distance of the rod; that is, the greater the downward movement of the rod, the greater the pressure. The pressure fluctuation range applied by the roller 4-2 to the deposition layer 5 is controlled within ±3% to ensure the consistency of the rolled products.

[0041] Example 3

[0042] A friction roll deposition forming apparatus, based on embodiment 2, further includes a linear motion mechanism for driving the rod to move along its length. The linear motion mechanism needs to be selected with high load-bearing capacity, sufficient rigidity, and high stability; for example, a hydraulic cylinder, ball screw, or rack (the rack is driven by a gear meshing with it) can be selected.

[0043] When the linear motion mechanism includes a ball screw, such as Figure 1 As shown, the roller pressing equipment 4 also includes: a motor 4-3 for driving the ball screw, a nut 4-1-2 for the ball screw fixed to the mounting base 1, a vertically arranged screw 4-1-1 for driving the rod body, or the bottom of the screw 4-1-1 serving as the rod body. Figure 1 As shown, the bottom of screw 4-1-1 serves as the rod body.

[0044] Motor 4-3 directly or indirectly drives the ball screw. When motor 4-3 directly drives the ball screw, the output shaft of motor 4-3 is fixedly connected to screw 4-1-1; when motor 4-3 indirectly drives the ball screw, the output shaft of motor 4-3 and screw 4-1-1 are transmitted through synchronous pulley set 4-5. Figure 1 As shown, motor 4-3 indirectly drives the ball screw.

[0045] The synchronous pulley set 4-5 includes: a driving synchronous pulley, a driven synchronous pulley, and a synchronous belt. The motor 4-3 drives the driving synchronous pulley to rotate. The driven synchronous pulley is fixed to the top of the screw 4-1-1. The synchronous belt is sleeved on the driving synchronous pulley and the driven synchronous pulley.

[0046] Preferably, the device also includes a reducer 4-4, whose input shaft is connected to the output shaft of the motor 4-3 via a coupling, and whose output shaft is fixed to the drive synchronous pulley to provide power input to the ball screw.

[0047] The friction roller deposition apparatus also includes a force sensor for real-time detection of the pressure applied by the rollers 4-2 to the deposition layer 5. The installation location of the force sensor is not limited, as long as it fulfills its function.

[0048] The stirred friction deposition apparatus 3 is not limited here, as long as it can perform stirred friction deposition, for example, the following existing technologies can be used:

[0049] [1]Yiming Huang*, Qi Liu, Kaiyue Zhang, Mingyu Li, Tianhao Yang, Lijun Yang, Lei Cui*. Investigation of three-dimensional forces during additive friction stir deposition—How could force signals reveal thedeposition quality?. International Journal of Machine Tools and Manufacture, 2025, 204: 104234.);

[0050] [2] A method for detecting defects in triboelectric deposition forming based on three-dimensional force time-frequency domain characteristics. Application No.: 202510597037.5.

[0051] Example 4

[0052] A friction roller deposition forming apparatus, based on Example 3, such as... Figure 1 and Figure 2As shown, the friction stir deposition apparatus 3 includes: a rotating shaft 3-1, a tool holder 3-3, a housing 3-6, and a shoulder 3-4. The tool holder 3-3 is fixedly mounted to the bottom of the rotating shaft 3-1, and the shoulder 3-4 is fixedly mounted to the bottom of the tool holder 3-3. The housing 3-6 is fitted over the rotating shaft 3-1, and a bearing is installed between the housing 3-6 and the rotating shaft 3-1. The rotating shaft 3-1 can rotate within the housing 3-6. The housing 3-6 is fixedly mounted to the mounting base 1. A first channel is formed at the centerline inside the rotating shaft 3-1, and a first channel is formed at the centerline inside the tool holder 3-3. A second channel is formed at the first point, and a third channel is formed at the center line inside the shoulder 3-4 (the third channel has an outlet hole at the bottom of the shoulder 3-4). The center lines of the first, second, and third channels are collinear, forming a conveying channel. A bar stock 3-5 is installed within the conveying channel. A push rod 3-2 is located above the bar stock 3-5 within the conveying channel and is used to push the bar stock 3-5 downward within the conveying channel. A guide cone is formed at the bottom of the shoulder 3-4 to guide the plasticized bar stock 3-5 to spread evenly onto the substrate 2. The outlet hole is located at the center of the guide cone.

[0053] Example 5

[0054] In the friction roller deposition forming apparatus of Example 4, the gap between the rod 3-5 and the inner wall of the conveying channel is 0.1 mm, and the distance between the bottom surface of the rod 3-5 and the surface of the substrate 2 is 4 mm.

[0055] The friction stir deposition apparatus 3 moves at a constant speed along a preset deposition path (traveling speed of 450 mm / min), the feed speed of the bar stock 3-5 is 300 mm / min, and the rotation speed of the shaft 3-1 is 700 rpm. The pressure applied to the deposited layer 5 by the roller 4-2 is 60 kN. The roller 4-2 is made of cemented carbide, has a diameter of 50 mm, and its surface is polished to reduce adhesion.

[0056] Substrate 2 is a 26061-T6 aluminum alloy plate with a thickness of 12mm. Substrate 2 requires pretreatment before friction stir deposition. The pretreatment includes: ultrasonically cleaning the surface of substrate 2 to be deposited with acetone for 10 minutes, followed by air drying to remove oil and oxide film; after drying, lightly polishing the surface to be deposited with 800#~1000# sandpaper to improve the surface roughness to Ra0.8~1.2. This facilitates frictional heat generation and mechanical engagement.

[0057] The material of bar 3-5 is SiCp / Al metal, and the cross-section of bar 3-5 is square with a side length of 15mm. The length of bar 3-5 is 120mm, and the bottom end of bar 3-5 is chamfered at 45° to facilitate the smooth entry of bar 3-5 into the conveying channel.

[0058] Comparative Example 1

[0059] A stirring friction deposition method is basically the same as the stirring friction deposition method in Example 5, except that the roller pressing equipment 4 is removed.

[0060] Stir-friction deposition was performed using the methods described in Example 5 and Comparative Example 1, respectively. After deposition, deposited parts (substrate 2 covered with deposited layer 5) were formed. The deposited parts were allowed to cool naturally to room temperature and then cut using an electrical discharge wire cutter to obtain samples. The samples were then sequentially polished with 240# to 2000# sandpaper, and then passed through a grinding wheel with a particle size of [missing information]. The deposited layer 5 was mechanically polished with diamond polishing paste, followed by etching with Keller's reagent for 10–15 s. The interface bonding state between the deposited layer 5 and the substrate 2 was observed using an optical microscope (ZEISS AX10). The results are as follows: Figure 3 As shown, where, Figure 3 (a) shows the interfacial bonding state of the stir-friction deposition method in Example 5. Figure 3 (b) shows the interfacial bonding state of the stir-friction deposition method in Comparative Example 1, which is composed of... Figure 3 It is known that rolling will cause severe plastic deformation of the deposited layer 5, thereby inducing dynamic recrystallization and refining the structure of the deposited layer 5.

[0061] The bonding strength between the deposited layer 5 and the substrate 2 in the deposited part was determined by single shear test, and the results are as follows: Figure 4 As shown in (a), it can be seen that the peak shear stress of the deposited part obtained by the friction stir deposition method in Comparative Example 1 is only about 20 MPa, and fracture occurs after 1% deformation, exhibiting brittle fracture characteristics. The shear stress of the deposited part obtained by the friction stir deposition method in Example 5 continuously increases with strain, and the peak shear stress exceeds 140 MPa, with the fracture strain approaching 10%, indicating that the friction stir deposition method of the present invention significantly improves the shear strength and plasticity of the material through roll pressing strengthening.

[0062] like Figure 4 As shown in (b), from both macroscopic and microscopic fracture perspectives, the fracture surface of the deposit obtained by the stir-friction deposition method in Comparative Example 1 is smooth and without obvious deformation, exhibiting intergranular fracture characteristics of brittle fracture; the fracture surface of the deposit obtained by the stir-friction deposition method in Example 5 shows obvious traces of plastic deformation, with numerous dimples at the fracture surface. This demonstrates that the roll-strengthened friction-deposited part has excellent plasticity and toughness, and the tendency of the wear-resistant layer (deposited layer 5) to peel off is significantly reduced.

[0063] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A friction stir welding method characterized by, The method comprises: Rolling the deposited layer (5) formed by the friction stir deposition, wherein the rolling is performed within 8-12 seconds after the formation of the deposited layer (5).

2. The friction stir deposition method of claim 1, wherein, The pressure for the rolling of the deposited layer (5) is 60-100 kN.

3. A friction roll press forming apparatus for carrying out the friction stir deposition method according to claim 1 or 2, wherein The method comprises: The friction stir deposition device (3) and the rolling device (4) are arranged on one side of the friction stir deposition device (3), and are both fixed on the mounting base (1). In the advancing direction of the friction stir deposition device (3), the rolling device (4) is located behind the friction stir deposition device (3). The rolling device (4) comprises a rod body and a rolling wheel (4-2). The rod body is vertically arranged, and the rolling wheel (4-2) is rotatably arranged at the bottom end of the rod body.

4. The friction roll press forming apparatus according to claim 3, wherein The rod body is movable along the length direction thereof.

5. The friction roll press forming apparatus according to claim 4, wherein The rolling device (4) further comprises a linear motion mechanism for driving the rod body to move along the length direction thereof.

6. The friction roll press forming apparatus according to claim 5, wherein The linear motion mechanism comprises a hydraulic cylinder, a ball screw or a rack.

7. The friction roll press forming apparatus according to claim 6, wherein When the linear motion mechanism comprises the ball screw, the rolling device (4) further comprises a motor (4-3) for driving the ball screw to move. The nut (4-1-2) of the ball screw is fixed on the mounting base (1), the screw rod (4-1-1) of the ball screw is vertically arranged, the screw rod (4-1-1) is fixed on the rod body for driving the rod body to move, or the bottom of the screw rod (4-1-1) is used as the rod body. The motor (4-3) directly or indirectly drives the ball screw to move. When the motor (4-3) directly drives the ball screw to move, the output shaft of the motor (4-3) is fixed on the screw rod (4-1-1). When the motor (4-3) indirectly drives the ball screw to move, the output shaft of the motor (4-3) is driven by the synchronous pulley set (4-5).

8. The friction roll press forming apparatus according to claim 7, wherein The friction rolling deposition forming device further comprises a force sensor for detecting the pressure applied by the rolling wheel (4-2) to the deposited layer (5) in real time.

9. Use of the friction stir deposition method according to claim 1 or 2 for improving the shear strength or plasticity in the friction stir deposition.

10. Use of the friction rolling deposition forming device according to any one of claims 3-8 for improving the shear strength or plasticity in the friction stir deposition.

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