A helical path stirred solid phase additive method

Abstract

The embodiment of the application discloses a spiral-path stirring solid-phase additive manufacturing method, comprising the following steps: fixing a workpiece to be added; driving a stirring head to make spiral ascending motion on the surface of the workpiece to be added; when the additive thickness of the workpiece to be added reaches a target thickness, stopping driving the stirring head, and obtaining a target additive workpiece. The stirring head is driven to ascend along a spiral path, so that the additive material is uniformly distributed, stress concentration and deformation caused by linear lifting of a tool are avoided, and the quality uniformity and manufacturing precision of an additive layer are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and more particularly to a stirring solid-phase additive manufacturing method with a helical path. Background Technology

[0002] Friction stir solid-state additive manufacturing (FSB) is a solid-state additive manufacturing technology based on the principle of friction stir. It utilizes a high-speed rotating stirring head to generate heat through friction with the matrix material, causing intense plastic flow and achieving metallurgical bonding between layers. Compared to traditional cladding additive manufacturing, this technology offers advantages such as low heat input, fine microstructure, low residual stress, and absence of pores and cracks, making it a promising candidate for high-performance additive manufacturing of lightweight alloy components such as aluminum and magnesium alloys.

[0003] Currently, linear upward-lifting processing paths are commonly used in friction stir solid-state additive manufacturing. This means that after completing one layer of additive manufacturing, the stirring head is lifted in a straight line to the starting point of the next layer, and then the next layer is added along the same straight path. While this path planning method is relatively simple, the following problems have been found in practical applications: First, the linear lifting position is prone to localized stress concentration, especially in the manufacturing of large parts, where the accumulated stress from multiple lifting operations can lead to workpiece deformation or even cracking. Second, the material flow at the lifting position is poor, easily forming bonding defects or uneven microstructure areas, affecting the overall performance consistency of the additive layers. Third, the linear path results in planar interfaces between additive layers, leading to uneven distribution of interlayer bonding strength, which limits the application of this technology under complex load conditions.

[0004] There is currently no effective solution to the above problems in existing technologies. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a helical path stirring solid-phase additive manufacturing method. By driving a stirring head to move along a helical path on the workpiece surface and rising layer by layer during the movement, the additive material is uniformly distributed under the action of the stirring head, thereby reducing stress concentration and deformation and improving the quality uniformity of the additive layer.

[0006] To achieve the above objectives, the present invention provides a helical path stirring solid-phase additive manufacturing method, comprising: fixing a workpiece to be additively manufactured; driving a stirring head to perform a helical upward motion on the surface of the workpiece to be additively manufactured; and stopping the stirring head when the additive thickness of the workpiece to be additively manufactured reaches a target thickness, thereby obtaining the target additively manufactured workpiece.

[0007] Optionally, the driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, including: real-time monitoring of the temperature of the stirring head; and adjusting the temperature to within the preset temperature range by a temperature control system when the temperature exceeds the preset temperature range.

[0008] Further optionally, before driving the stirring head to perform a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: driving the stirring head to perform additive manufacturing on the simulated test plate at an initial moving speed; gradually increasing the initial moving speed by a first preset adjustment amount and recording the additive mass corresponding to each speed increase; selecting the moving speed range corresponding to when the additive mass meets the first preset condition, and using the median value of the moving speed range as the actual moving speed of the stirring head.

[0009] Further optionally, before driving the stirring head to perform a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: driving the stirring head to perform additive manufacturing on the simulated test plate at an initial pitch; gradually adjusting the initial pitch according to a second preset adjustment amount, and recording the additive mass corresponding to each pitch adjustment; and selecting the pitch corresponding to the highest additive mass as the actual pitch of the stirring head.

[0010] Further optionally, before driving the stirring head to make a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: driving the stirring head to rotate at an initial rotational speed under no-load conditions; gradually adjusting the initial rotational speed according to a third preset adjustment amount, and recording the operating characteristic value of the stirring head each time the speed is increased; selecting the rotational speed range corresponding to the characteristic value satisfying a second preset condition, and taking the median value of the rotational speed range as the actual rotational speed of the stirring head.

[0011] Further optional features include: during the additive manufacturing process, whenever the additive thickness increases by a preset layer thickness value, pausing the driving of the stirring head and performing surface treatment on the current additive layer; after the surface treatment is completed, continuing to drive the stirring head to perform the additive operation.

[0012] Further optionally, after obtaining the target additive workpiece, the process includes performing at least one of heat treatment, machining, and surface treatment on the target additive workpiece.

[0013] Further optionally, the heat treatment includes: solution treatment of the target additive workpiece; water quenching of the solution-treated target additive workpiece; and artificial aging treatment of the water-quenched target additive workpiece.

[0014] Further optionally, the machining includes: cutting the target additive workpiece to a preset size to obtain a shaped workpiece.

[0015] Further optionally, the surface treatment includes: anodizing the target additive workpiece.

[0016] The above technical solution has the following beneficial effects: by moving the stirring head along a spiral path and rising layer by layer on the surface of the workpiece to be additively manufactured, the local stress accumulation at the linear tool lifting position is avoided, achieving a uniform distribution of residual stress in the additive layer and reducing workpiece deformation; the spiral path allows the additive material to be continuously and uniformly spread under the action of the stirring head, improving the thickness consistency and microstructure uniformity of the additive layer; by monitoring the temperature of the stirring head in real time and adjusting it to a preset range, the steady-state operation of the additive process is ensured, improving the batch stability of the additive layer performance; by automatically controlling the spiral upward movement of the stirring head and the process parameters, continuous solid-phase additive manufacturing of large parts is realized, improving production efficiency and quality consistency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the helical path stirring solid-phase additive manufacturing method provided in the embodiments of the present invention; Figure 2 This is a flowchart of the temperature control method provided in an embodiment of the present invention; Figure 3 This is a flowchart of the method for determining movement speed provided in an embodiment of the present invention; Figure 4 This is a flowchart of the pitch determination method provided in the embodiments of the present invention; Figure 5 This is a flowchart of the rotation speed determination method provided in the embodiments of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To address the problems of uneven additive layer quality and stress concentration and deformation at the tool lifting position in existing additive manufacturing processes, this invention provides a helical path stirring solid-phase additive manufacturing method. Figure 1 This is a flowchart of the helical path stirring solid-phase additive manufacturing method provided in an embodiment of the present invention, as follows: Figure 1 As shown, it includes: S1. Fix the workpiece to be added.

[0021] The workpiece to be added is selected according to actual needs. For example, 6061 aluminum alloy sheet with dimensions of 300 mm × 300 mm × 15 mm can be used.

[0022] Before fixing, the workpiece surface is pretreated: mechanical grinding is used to remove surface oil and oxide scale, so that the surface roughness of the workpiece reaches Ra 1.6μm, and then it is cleaned with anhydrous ethanol and dried.

[0023] The processed workpiece is placed on the worktable of the friction stir solid-phase additive manufacturing equipment. Preferably, the worktable surface has T-slots, and a clamping plate and bolt assembly are used to evenly press the four corners of the workpiece to ensure that the workpiece does not undergo horizontal displacement or warping during the additive manufacturing process. The clamping force is controlled between 500 N and 1000 N. A water-cooling circulation system is provided under the worktable to control the substrate temperature during the additive manufacturing process, with the initial cooling water temperature set at 20℃±2℃. Alternatively, the workpiece can be fixed in place using clamping heads.

[0024] After the workpiece is fixed, the flatness of the upper surface is measured with a dial indicator to ensure that the overall flatness error does not exceed 0.05 mm. If there is unevenness in some areas, shims are used for fine adjustment to ensure that the initial layer thickness of the subsequent spiral path additive manufacturing is uniform.

[0025] S2. Drive the stirring head to make a spiral upward motion on the surface of the workpiece to be added.

[0026] The spiral upward motion refers to a composite motion in which the stirring head moves continuously along an Archimedean spiral (or an equidistant spiral) in the horizontal plane, while simultaneously rising layer by layer in the vertical direction (Z-axis) with a preset pitch. Specifically, the shoulder of the stirring head maintains a constant contact pressure with the workpiece surface. While generating heat through rotational friction, its horizontal projection trajectory is a spiral line continuously expanding outward (or inward) from the center. Each complete spiral rotation causes the stirring head to rise by a preset layer thickness in the Z-axis direction, allowing the additive material to accumulate layer by layer under the crushing action of the stirring head and form a metallurgical bond until the target additive thickness is reached. This motion eliminates the start-stop reversal and interlayer lifting actions in traditional linear tool lifting paths, achieving continuity in the additive process and smoothing of interlayer transitions.

[0027] Start the friction stir solid additive manufacturing equipment. The stirring head is made of high-strength tool steel. The stirring needle is preferably 8 mm in diameter and 6 mm in length. The shoulder diameter of the stirring head is 20 mm. The surface is coated with a wear-resistant and thermally conductive coating.

[0028] The control system sets the rotational speed, moving speed, and pitch of the spiral path of the stirring head. The stirring head first descends until its shoulder makes slight contact with the workpiece surface, then starts rotating and begins to move along the preset spiral path.

[0029] The stirring head employs a spiral-ascending solid-phase additive manufacturing method, meaning it rises in a helical path during the additive process, gradually increasing the thickness of the additive layer. This method allows for a more uniform material distribution within the additive layer under the action of the stirring head, reducing stress concentration and deformation. The spiral upward motion of the stirring head is achieved through a ball screw and linear guide, driven by a servo motor to complete the additive operation.

[0030] Simultaneously with additive manufacturing, a welding wire identical to the workpiece to be additively manufactured is continuously fed into the area in front of the shoulder of the stirring head via a wire feeding device. In an optional embodiment, for 6061 aluminum alloy plates, a 2mm diameter 6061 aluminum alloy welding wire is used. The welding wire must be cleaned and dried before use to ensure that the surface of the welding wire is clean and free of impurities. The friction between the stirring head, the workpiece, and the welding wire generates heat, causing the aluminum alloy material to undergo intense plastic flow, forming a dense additive layer under the rolling action of the stirring head. With each additional layer, the thickness of the additive layer increases by approximately 0.5 mm to 1.0 mm (depending on the pitch and material flow characteristics).

[0031] In one alternative embodiment, the forging force of the stirring head is controlled between 5000N and 8000N, and adjusted according to the thickness of the additive layer and the fluidity of the material.

[0032] As an optional implementation, the entire additive manufacturing process is carried out in an argon protective atmosphere to prevent high-temperature oxidation of the aluminum alloy.

[0033] S3. When the additive thickness of the workpiece reaches the target thickness, stop driving the stirring head to obtain the target additive workpiece.

[0034] During the additive manufacturing process, the control system records the total vertical displacement of the stirring head in real time, and the cumulative value of this displacement is the total thickness of the additive layer. For example, if the target additive thickness is set to 10 mm, the corresponding total distance the stirring head rises from the starting position (workpiece surface) is 10 mm.

[0035] When the control system detects that the cumulative upward displacement of the stirring head along the Z-axis has reached the target thickness, it determines that the additive thickness has met the target requirements. At this point, the control system first stops the wire feeding device, then allows the stirring head to continue rotating for 3–5 seconds to eliminate material accumulation at the tail end. Subsequently, the rotation speed is gradually reduced to 0 rpm, while the stirring head is smoothly lifted about 5 mm above the workpiece surface.

[0036] Turn off the equipment drive power and wait until the stirring head has completely stopped rotating before removing the workpiece along with the worktable from the equipment. Disassemble the pressure plate assembly from the worktable and remove the additively processed workpiece. Visually inspect the workpiece surface to confirm that there are no obvious macroscopic cracks, holes, or delamination defects. Mark it as the target additively processed workpiece and transfer it to the post-processing stage.

[0037] To ensure the quality and performance of the additive layer, it is necessary to inspect and control the quality of the helical upward spiral path stirring solid-phase additive manufacturing method. Quality inspection can be carried out using non-destructive testing techniques, such as ultrasonic phased array flaw detection and X-ray inspection, to detect internal defects and quality of the additive layer.

[0038] Quality control can be achieved by real-time monitoring of various parameters in the additive manufacturing process, such as stirring head rotation speed, moving speed, and upsetting force, as well as by detecting and providing feedback on the quality of the additive layer.

[0039] As an optional implementation method, Figure 2 This is a flowchart of the temperature control method provided in an embodiment of the present invention, such as... Figure 2 As shown, the driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, including: S201. Real-time monitoring of the temperature of the stirring head.

[0040] A temperature sensor is installed on the mixing head to continuously monitor the temperature of the mixing head body during the additive manufacturing process. The temperature sensor transmits the detected signal to the control system, which reads the temperature value at a preset sampling frequency and displays or stores it in real time. Real-time monitoring allows for the acquisition of a temperature change curve of the mixing head during the spiral upward additive manufacturing process, providing data for subsequent temperature adjustment. The installation location of the temperature sensor includes, but is not limited to, the shoulder of the mixing head, the root of the mixing needle, or the clamping part of the mixing head.

[0041] In one specific embodiment, a blind hole is formed on the shoulder of the stirring head near the base of the stirring needle. A thermocouple with a response time ≤0.1 seconds is embedded in the hole. The gap between the thermocouple and the inner wall of the blind hole is filled with high thermal conductivity silicone grease, and the thermocouple is fixed and sealed with high-temperature resistant ceramic adhesive to ensure good contact between the thermocouple and the stirring head body and prevent loosening.

[0042] The thermocouple's compensating leads are led out through an axial through-hole inside the stirring head and connected to the temperature acquisition module of the control system. The temperature acquisition frequency of the control system is set to 10 Hz, meaning it records 10 temperature data points per second. The acquired temperature values ​​are displayed in real time on the human-machine interface and simultaneously stored in the process log file.

[0043] During the additive manufacturing process, based on the characteristics of the friction stir solid-state additive manufacturing process for aluminum alloys, this embodiment sets the preset normal temperature range to 200℃~300℃. When the displayed temperature value is below 200℃, it indicates that the stirring head is not generating enough heat; when the displayed temperature value is above 300℃, it indicates that the stirring head is overheating. The control system displays blue and red backgrounds on the interface to alert the operator and triggers corresponding temperature adjustment actions.

[0044] To improve the reliability of temperature measurement, in another embodiment, a dual thermocouple redundancy scheme can be adopted: two identical thermocouples are installed at 180° intervals around the shoulder of the stirring head, and the control system takes the average temperature of the two thermocouples as the actual monitored temperature. If the readings of the two thermocouples deviate by more than 20°C, an alarm message is issued, prompting a check of the sensor status.

[0045] S202. When the temperature exceeds the preset temperature range, the temperature is adjusted to the preset temperature range through the temperature control system.

[0046] The control system compares the real-time monitored temperature of the stirring head with a preset temperature range. When the temperature is below the lower limit of the preset range, it indicates insufficient heat generation. The control system increases the frictional heat input by increasing the rotation speed of the stirring head, decreasing the moving speed, or increasing the upsetting force, causing the temperature to rise back to the normal range. When the temperature is above the upper limit of the preset range, it indicates overheating. The control system reduces the temperature by activating the cooling system (e.g., spraying cooling gas / liquid onto the stirring head or workpiece), decreasing the rotation speed, increasing the moving speed, or decreasing the upsetting force. The temperature control system can be an independent cooling device or a functional module that adjusts the stirring head's process parameters to regulate the temperature.

[0047] As a specific implementation method, when the monitored temperature is below 200°C for three consecutive samplings (i.e., within 0.3 seconds), the control system determines that the temperature is too low. At this time, the control system performs the following heating operation: Gradually increase the rotational speed of the stirring head from its current value. For example, if the current value is 1500 rpm, increase it by 50 rpm each time, with a maximum increase of 2500 rpm, until the temperature rises above 200°C. If the temperature is still below 200°C after the rotational speed has been increased to 2500 rpm, simultaneously gradually decrease the moving speed of the stirring head from 60 mm / min, decreasing it by 5 mm / min each time, with a minimum decrease of 20 mm / min, to increase the frictional heat input per unit path.

[0048] When the monitored temperature exceeds 300℃ for three consecutive samples, the control system determines that the temperature is too high. At this time, the control system executes the following cooling operation: First, activate the cooling system. The cooling system uses nozzles located above the stirring head to spray compressed air onto the shoulder of the stirring head. The compressed air pressure should be 0.3 MPa, and the flow rate 50 L / min. Simultaneously, gradually reduce the rotational speed of the stirring head, for example, by 50 rpm each time, with a lower limit of 1200 rpm. If the temperature remains above 300°C after activating cooling and reducing the speed, further increase the stirring head's movement speed, for example, by 10 mm / min each time, with an upper limit not exceeding 150 mm / min, to reduce heat accumulation per unit path.

[0049] If the temperature exceeds the threshold by too much, such as 350°C, the control system will immediately stop the movement and rotation of the stirring head and issue an audible and visual alarm. Additive manufacturing will resume once the temperature drops below 250°C.

[0050] As an optional implementation, before driving the stirring head to make a spiral upward motion on the surface of the workpiece to be additively manufactured, Figure 3 This is a flowchart of the method for determining movement speed provided in an embodiment of the present invention, such as... Figure 3 As shown, it includes: S4. Drive the stirring head to perform additive manufacturing on the simulated test plate at the initial moving speed.

[0051] S5. Gradually increase the initial moving speed according to the first preset adjustment amount, and record the additive mass corresponding to each speed increase.

[0052] S6. Select the range of moving speeds corresponding to when the additive mass meets the first preset condition, and take the middle value of the moving speed range as the actual moving speed of the stirring head.

[0053] Before the actual additive manufacturing process, the moving speed is adjusted using a simulated test plate. Starting with an initial moving speed as a baseline, the speed is gradually increased under the same conditions. After each increase, the surface quality, thickness uniformity, and internal defects of the additive layer are observed and recorded. This determines a range of moving speeds that yields good additive quality, and the midpoint of this range is taken as the actual moving speed during additive manufacturing. This moving speed can be adjusted in real time during the additive manufacturing process according to actual conditions.

[0054] In one specific embodiment, the simulation test plate uses the same 6061 aluminum alloy sheet as the workpiece to be additively processed, with dimensions of 200 mm × 200 mm × 15 mm, and the surface is pretreated to Ra 1.6 μm. The initial moving speed is set to 10 mm / min, the stirring head rotation speed is fixed at 1500 rpm, the forging force is fixed at 6000 N, and the pitch is fixed at 8 mm. Single-layer additive processing is performed on the simulation test plate at speeds of 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, and 150 mm / min, with an additive length of 100 mm at each speed. After each additive processing cycle, the surface ripples, edge flash, and surface roughness of the additive layer are observed, and a cross-section is cut to measure the thickness uniformity. The results were as follows: When the moving speed was 10–30 mm / min, the additive layer surface was rough and there was excessive material buildup; when the speed was 40–80 mm / min, the surface was smooth and the thickness uniformity was optimal (range ≤ 0.1 mm); when the speed was 90–150 mm / min, surface grooves and incomplete filling defects appeared. Therefore, the moving speed range that satisfies the first preset condition (smooth surface, thickness range ≤ 0.1 mm) was determined to be 40–80 mm / min, and the midpoint of 60 mm / min was taken as the actual moving speed of the stirring head. Through the above adjustments, additive layer quality defects caused by improper moving speed can be avoided, ensuring the stability of the spiral upward additive process.

[0055] As an optional implementation, before driving the stirring head to make a spiral upward motion on the surface of the workpiece to be additively manufactured, Figure 4 This is a flowchart of the pitch determination method provided in the embodiments of the present invention, such as... Figure 4 As shown, it includes: S7. Drive the stirring head to perform additive manufacturing on the simulated test plate according to the initial pitch.

[0056] S8. Gradually adjust the initial pitch according to the second preset adjustment amount, and record the additive mass corresponding to each pitch adjustment.

[0057] S9. Select the pitch corresponding to the highest additive quality as the actual pitch of the mixing head.

[0058] Before the actual additive manufacturing process, the pitch of the spiral path is adjusted using a simulated test plate. Using an initial pitch as a reference, the pitch is gradually increased or decreased under the same conditions by a preset adjustment amount. After each adjustment, additive manufacturing quality indicators such as the uniformity of the additive layer thickness, surface flatness, and interlayer bonding quality are observed and recorded. This process determines a pitch value that yields the optimal additive manufacturing quality, which is then used as the pitch for the actual additive manufacturing process. This pitch can be adjusted in real time during the additive manufacturing process according to actual conditions.

[0059] In one optional implementation, the simulated test plate is made of 6061 aluminum alloy sheet with dimensions of 200 mm × 200 mm × 15 mm, and the surface is pretreated to Ra 1.6 μm. The stirring head rotation speed is fixed at 1500 rpm, the moving speed is fixed at 60 mm / min, and the forging force is fixed at 6000 N. The initial pitch is set to 10 mm, and the second preset adjustment is a decrease of 1 mm each time. Single-layer additive manufacturing is performed on the simulated test plate with pitches of 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, and 5 mm, respectively, with an additive length of 150 mm at each pitch. After each additive manufacturing operation, the thickness uniformity of the additive layer is measured (thickness is measured at 5 points along the path, and the range is calculated), and the surface quality is observed. The results are as follows: With a pitch of 10 mm, the thickness variation is 0.25 mm, and the surface has obvious ripples; with a pitch of 9 mm, the thickness variation is 0.18 mm, and the ripples are reduced; with a pitch of 8 mm, the thickness variation is 0.08 mm, and the surface is smooth and flat; with a pitch of 7 mm, the thickness variation is 0.10 mm, and the surface has slight burrs; with a pitch of 6 mm, the thickness variation is 0.12 mm, and localized material accumulation occurs; with a pitch of 5 mm, the thickness variation is 0.20 mm, and the surface is rough. The pitch corresponding to the highest additive manufacturing quality (combined thickness uniformity and surface flatness) is 8 mm. Therefore, 8 mm is selected as the actual pitch of the stirring head. Through the above adjustments, it can be ensured that the pitch of the spiral path matches the process parameters, making the thickness of each additive layer uniform and consistent.

[0060] As an optional implementation, before driving the stirring head to make a spiral upward motion on the surface of the workpiece to be additively manufactured, Figure 5 This is a flowchart of the rotation speed determination method provided in an embodiment of the present invention, such as... Figure 5 As shown, it includes: S10. Under no-load conditions, drive the stirring head to rotate at the initial rotation speed.

[0061] S11. Gradually adjust the initial rotation speed according to the third preset adjustment amount, and record the operating characteristic value of the stirring head each time the speed is increased.

[0062] S12. Select the rotational speed range corresponding to the feature value satisfying the second preset condition, and take the middle value of the rotational speed range as the actual rotational speed of the stirring head.

[0063] Before the actual additive manufacturing process, the stirring head is rotated under no-load conditions (without contact with any workpiece or test plate). Using an initial rotational speed as a reference, the rotational speed is gradually increased by a preset adjustment amount. After each increase, the operating characteristics of the stirring head are observed and recorded, including but not limited to operational stability (such as vibration amplitude and rotational smoothness) and noise level. When the operating characteristics meet a second preset condition (such as vibration amplitude below a threshold and no abnormal noise), the corresponding rotational speed range is considered the reasonable rotational speed range. The midpoint of this range is taken as the actual rotational speed during additive manufacturing. This rotational speed can be adjusted in real time during the additive manufacturing process according to actual conditions.

[0064] In one specific embodiment, the stirring head is mounted on the drive spindle, and the device is started under no-load conditions. The initial rotational speed is set to 500 rpm, with a third preset adjustment increment of 100 rpm, operating sequentially at 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, and 2500 rpm, each speed for 30 seconds. Operating characteristics include the vibration amplitude of the stirring head spindle housing measured by an accelerometer (in m / s). 2 The noise level (in dB) was measured at a distance of 1 m from the stirring head using a sound level meter. The results were recorded as follows: vibration amplitude ≤ 0.5 m / s at rotational speeds of 500–1100 rpm. 2 Noise level ≤70 dB, stable operation; vibration amplitude ≤0.8 m / s at speeds of 1200–1800 rpm. 2 Noise level ≤75 dB, no abnormal noise; vibration amplitude ≥1.5 m / s at speeds of 1900–2500 rpm. 2 The noise level is ≥85 dB, with noticeable high-frequency vibrations and sharp noise. The second preset condition is set as follows: vibration amplitude ≤1.0 m / s. 2 Furthermore, the noise level should be ≤80 dB. The rotational speed range to meet this condition is 1200–1800 rpm, with the midpoint of 1500 rpm taken as the actual rotational speed of the mixing head. Through no-load testing, instability of the mixing head or excessive wear of the equipment during additive manufacturing can be avoided due to improper rotational speed, thus providing a prerequisite for obtaining stable additive manufacturing quality.

[0065] As an optional implementation, the method further includes: during the additive manufacturing process, whenever the additive thickness increases by a preset layer thickness value, pausing the driving of the stirring head and performing surface treatment on the current additive layer; after the surface treatment is completed, continuing to drive the stirring head to perform the additive operation.

[0066] During the spiral additive manufacturing process, when the cumulative additive thickness reaches a preset layer thickness increment, the control system pauses the rotation and movement of the stirring head. Operators or automated equipment then clean the surface of the currently formed additive layer, removing burrs, flash, and surface impurities generated by plastic flow. After surface treatment, the stirring head is restarted, and the next layer of additive manufacturing continues along the spiral path from its stopped position. This process can be repeated multiple times until the total additive thickness reaches the target value. Layered surface treatment prevents impurities and burrs from being drawn into subsequent layers, improving the interlayer bonding quality.

[0067] In one specific embodiment, the preset layer thickness is set to 2 mm. The workpiece to be additively processed is 6061 aluminum alloy, and the target additive thickness is 10 mm. During the additive processing, the control system records the Z-axis upward displacement of the stirring head (i.e., the current total additive thickness) in real time. When the cumulative additive thickness reaches 2 mm, the control system performs the following operations: first, it stops wire feeding; then, it reduces the stirring head rotation speed to 500 rpm and pauses movement; next, it slowly lifts the stirring head about 3 mm above the workpiece surface; finally, it stops rotating completely. The operator uses a stainless steel brush or a compressed air gun (pressure 0.2 MPa) to clean the surface of the current additive layer, removing edge flash, surface burrs, and oxide debris. After cleaning, the surface is visually inspected for any residual impurities. Subsequently, the control system restarts the stirring head, lowering it to the height before the pause at a speed of 1500 rpm and a moving speed of 60 mm / min, and continues additive processing along the spiral path for the next layer. When the cumulative additive thickness reaches 4 mm, 6 mm, and 8 mm, the above pause, surface cleaning, and continued additive processing steps are repeated. When the final thickness reaches 10 mm, the pause and cleaning process is no longer performed. By performing surface treatment every 2 mm, surface burrs and impurities generated after each layer of additive manufacturing are effectively eliminated, interlayer inclusion defects are avoided, and the final 10 mm thick additive workpiece has a dense internal structure and good interlayer bonding.

[0068] As an optional implementation, after obtaining the target additive workpiece, the process includes performing at least one of heat treatment, machining, and surface treatment on the target additive workpiece.

[0069] After additive manufacturing is completed, the target additive workpiece undergoes post-processing according to the performance requirements and dimensional accuracy requirements of the workpiece. Heat treatment is used to eliminate residual stress generated during additive manufacturing and improve mechanical properties; machining is used to remove excess material, improve dimensional accuracy and surface smoothness; surface treatment is used to enhance corrosion resistance and appearance quality.

[0070] As an optional implementation, the heat treatment includes: solution treatment of the target additive workpiece; water quenching of the solution-treated target additive workpiece; and artificial aging treatment of the water-quenched target additive workpiece.

[0071] Solution treatment is performed on the target additive workpiece, which involves heating the workpiece to a specific temperature and holding it at that temperature for a certain period of time to allow the soluble phase in the alloy to fully dissolve and form a supersaturated solid solution. Subsequently, a rapid water quenching treatment is performed to quickly cool the high-temperature solid solution to room temperature, maintaining the supersaturated state. Finally, artificial aging treatment is performed, which involves heating the water-quenched workpiece to a lower temperature and holding it at that temperature to allow the supersaturated solid solution to precipitate fine and dispersed strengthening phases, thereby significantly improving the strength, hardness, and microstructure stability of the workpiece.

[0072] In one specific implementation, the additively manufactured workpiece is placed in a heat treatment furnace for solution treatment at a temperature of 530°C for 2 hours, followed by rapid water quenching. Then, artificial aging treatment is performed at 175°C for 8 hours.

[0073] As an optional implementation, machining includes: cutting the target additive workpiece to a preset size to obtain a shaped workpiece.

[0074] After additive manufacturing and heat treatment, the workpiece surface typically has burrs, flash, and dimensional allowances. Excess material needs to be removed through machining to ensure the workpiece meets the final dimensions, shape accuracy, and surface quality requirements of the design drawings. Machining accuracy is controlled within ±0.05mm.

[0075] As an optional implementation, the surface treatment includes anodizing the target additive workpiece.

[0076] Anodizing the workpiece improves its corrosion resistance and aesthetics. The oxide film thickness is controlled between 10μm and 20μm.

[0077] The above technical solution has the following beneficial effects: by moving the stirring head along a spiral path and rising layer by layer on the surface of the workpiece to be additively manufactured, the local stress accumulation at the linear tool lifting position is avoided, achieving a uniform distribution of residual stress in the additive layer and reducing workpiece deformation; the spiral path allows the additive material to be continuously and uniformly spread under the action of the stirring head, improving the thickness consistency and microstructure uniformity of the additive layer; by monitoring the temperature of the stirring head in real time and adjusting it to a preset range, the steady-state operation of the additive process is ensured, improving the batch stability of the additive layer performance; by automatically controlling the spiral upward movement of the stirring head and the process parameters, continuous solid-phase additive manufacturing of large parts is realized, improving production efficiency and quality consistency.

[0078] The above-described specific embodiments of the invention further illustrate the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above content is only for specific embodiments of the invention and is not intended to limit the scope of protection of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for stirring solid-phase additive manufacturing along a spiral path, characterized in that, include: Fix the workpiece to be added; The stirring head is driven to make a spiral upward motion on the surface of the workpiece to be added; When the additive thickness of the workpiece to be additively manufactured reaches the target thickness, the stirring head is stopped, and the target additively manufactured workpiece is obtained.

2. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, The driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, including: Real-time monitoring of the temperature of the stirring head; When the temperature exceeds the preset temperature range, the temperature is adjusted back to the preset temperature range by the temperature control system.

3. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, Before the driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: The stirring head is driven to perform additive manufacturing on the simulated test plate at the initial moving speed; The initial moving speed is gradually increased according to the first preset adjustment amount, and the additive mass corresponding to each increase in speed is recorded; Select the range of moving speeds corresponding to when the additive quality meets the first preset condition, and take the middle value of the moving speed range as the actual moving speed of the stirring head.

4. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, Before the driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: The stirring head is driven to perform additive manufacturing on the simulated test plate according to the initial pitch; The initial pitch is gradually adjusted according to the second preset adjustment amount, and the additive mass corresponding to each pitch adjustment is recorded. The pitch corresponding to the highest additive quality is selected as the actual pitch of the mixing head.

5. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, Before the driving stirring head performs a spiral upward motion on the surface of the workpiece to be additively manufactured, the process includes: Under no-load conditions, the stirring head is driven to rotate at the initial rotational speed; The initial rotation speed is gradually adjusted according to the third preset adjustment amount, and the operating characteristic value of the stirring head is recorded each time the speed is increased; Select the rotational speed range corresponding to the feature value satisfying the second preset condition, and take the median value of the rotational speed range as the actual rotational speed of the stirring head.

6. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, Also includes: During the additive manufacturing process, whenever the additive thickness increases by a preset layer thickness value, the driving of the stirring head is paused, and the current additive layer is surface treated. After the surface treatment is completed, continue to drive the stirring head to perform additive manufacturing.

7. The helical path stirring solid-phase additive manufacturing method according to claim 1, characterized in that, After obtaining the target additive workpiece, the following are included: The target additive workpiece is subjected to at least one of heat treatment, machining, and surface treatment.

8. The method for stirring solid-phase additive manufacturing along a spiral path according to claim 7, characterized in that, The heat treatment includes: The target additive workpiece is subjected to solution treatment; The target additive workpiece after solution treatment is then subjected to water quenching. The target additive workpiece after water quenching is then subjected to artificial aging treatment.

9. The helical path stirring solid-phase additive manufacturing method according to claim 7, characterized in that, The machining process includes: The target additive workpiece is machined according to a preset size to obtain a shaped workpiece.

10. The method for stirring solid-phase additive manufacturing along a spiral path according to claim 7, characterized in that, The surface treatment includes: The target additive workpiece is subjected to anodizing treatment.

Images