A Precision Cooling and Temperature Control Device and Method for Friction Stir Additive Manufacturing of Complex Components

Abstract

This invention discloses a precise cooling and temperature control device and method for complex component friction stir additive manufacturing. The device comprises an additive manufacturing system, a temperature acquisition system, a cooling system, and a control system. The device and method utilize a combination of metal steel balls and coolant to overcome the lower thermal conductivity of pure coolant compared to pure metal, thereby increasing the supercooling of the component structure during cooling. This allows for faster heat dissipation during the layer-by-layer additive manufacturing process, significantly improving forming speed and microstructure uniformity. The temperature acquisition steel balls collect temperatures above and below the coolant surface, enabling precise characterization of the temperature gradient in the additive component. Combined with a time-sensitive factor and a control system, precise cooling and temperature control are achieved.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for metallic materials, specifically relating to a precise cooling and temperature control device and method for friction stir additive manufacturing of complex components. Background Technology

[0002] Friction stir additive manufacturing (FSAM) has become one of the most promising solid-state additive manufacturing technologies for manufacturing metal components. This technology utilizes frictional heat and plastic deformation generated by a stirring head (consumable or non-consumable) to deposit the metal to be added onto the already added metal, repeating this process layer by layer to form the material according to design requirements. Compared to melt-based additive manufacturing, since there is no melting and solidification of the material during the additive process, thermal stress defects such as cracks and pores are avoided. Furthermore, the intense plastic deformation provides a uniform and dense equiaxed microstructure, significantly improving the overall mechanical properties of the component. However, this technology also has some problems. During the layer-by-layer additive manufacturing of metal components, subsequent additive passes have a thermal effect on the microstructure of previous passes. With multiple additive passes, the microstructure of the first-pass additive undergoes frequent thermal cycling, which can lead to grain growth at the bottom of the additive layer and coarsening of the second-phase microstructure in the alloy. Ultimately, this results in the formed component exhibiting microstructure inhomogeneity and anisotropy of mechanical properties along the additive thickness direction, affecting the component quality.

[0003] For the reasons mentioned above, there is an urgent need to propose a new method to solve the problem of heat accumulation during the manufacturing of complex components by friction stir additive manufacturing, and to effectively achieve precise cooling and temperature control. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to solve the problem of heat accumulation during the manufacturing of complex components by friction stir additive manufacturing, and to provide a precise cooling and temperature control device and method.

[0005] To achieve the above-mentioned objectives, the technical solution of this invention is as follows:

[0006] A precision cooling and temperature control device for friction stir additive manufacturing of complex components includes: an additive manufacturing system, a temperature acquisition system, a cooling system, and a control system;

[0007] The additive manufacturing system includes a friction stir additive manufacturing spindle tool head, a fixture, and a substrate. The friction stir additive manufacturing spindle tool head can be mounted on external processing equipment such as CNC machine tools and parallel robotic arms. The substrate is fixed to the base of the processing cylinder by the fixture.

[0008] The temperature acquisition system includes temperature acquisition steel balls equipped with thermocouples. Multiple temperature acquisition steel balls are arranged at equal intervals among ordinary steel balls around the additive component, responsible for collecting real-time temperatures of different parts of the additive component. They are connected to a data acquisition card via high-temperature resistant data cables. As the height of the additive component increases, multiple layers of parallel temperature acquisition steel balls are arranged around the additive component. Simultaneously, with the injection of coolant, a layer of temperature acquisition steel balls is formed above the liquid surface and a layer below the liquid surface.

[0009] The cooling system includes a machining cylinder, ordinary steel balls, coolant, an injection valve, an output valve, a flow guide, and a wire mesh. The coolant is injected into the machining cylinder through the injection valve and flows out of the machining cylinder through the output valve. The flow guide is connected to the threaded outlet hole at the bottom of the machining cylinder through a screw hole. The height of the flow guide is set according to the additive manufacturing height, which can deliver the coolant from bottom to top to the closed, corner, or other parts of the complex component where the liquid flow is not smooth. The wire mesh is laid on the bottom surface of the machining cylinder to prevent the ordinary steel balls from blocking the outlet hole at the bottom surface of the machining cylinder.

[0010] Preferably, the processing cylinder consists of modular special side plates and bottom plates, as well as a base.

[0011] Preferably, the modular special side plates and bottom plates can be arbitrarily assembled and connected by means of dovetail grooves, slide rails, etc.

[0012] Preferably, the bottom plate has a through flow channel inside, and the two ends of the flow channel can be sealed as needed. The flow channel is connected to the inside of the processing cylinder through a threaded liquid outlet hole. The bottom plate surface inside the processing cylinder has a fixing hole, and the diameter of the liquid outlet hole is 5mm to 10mm.

[0013] Preferably, the base consists of support legs and a base plate. The support legs are connected to the bottom surface of the processing cylinder by bolts and fixing holes. The height of the support legs is generally between 50mm and 200mm. The base plate has rectangular, trapezoidal, triangular, rhomboid, and other shapes, and can be arranged and combined in any way to form the support base required for complex components.

[0014] Preferably, the diameter of the ordinary steel ball is 1.2mm to 10mm, and the material can be stainless steel, bearing steel, carbon steel, etc.

[0015] Preferably, the coolant can be a fluid with a high melting point and high thermal conductivity, such as water, propylene glycol, or alumina nanofluid.

[0016] Preferably, both the injection valve and the output valve are solenoid valves with liquid flow control modules, which can control the liquid flow rate per unit time. The injection valve and the output valve are connected to both ends of the flow channel through pipes respectively.

[0017] Preferably, the flow guide is a hollow tube with openings at both ends, one end of which has external threads and can be connected to the threaded liquid outlet hole on the bottom surface of the processing cylinder.

[0018] Preferably, the mesh size of the metal wire mesh is smaller than the diameter of the steel ball to prevent ordinary steel balls from blocking the liquid outlet holes on the inner wall of the processing cylinder.

[0019] The control system includes a data acquisition card and a computer control system. The thermocouple, solenoid valve, and communication terminal of the stirring friction amplification spindle tool head are connected to the data acquisition card. The data acquisition card communicates with the computer control system via a USB interface. The data acquisition card is responsible for converting input and output signals, while the computer control system is responsible for signal processing.

[0020] To achieve the above-mentioned objectives, the present invention also provides a method for precise cooling and temperature control in friction stir additive manufacturing of complex components, employing the aforementioned apparatus and comprising the following steps:

[0021] Step 1: Based on the shape characteristics of the complex component to be additively formed, select a suitable base plate combination and install it as a base in the processing cylinder. Fix the surface-polished substrate (thickness d) onto the base using a fixture. Then, according to the planar position of the closed and corner areas of the complex component, connect one end of the flow guide to the bottom plate of the processing cylinder. The flow guide can deliver coolant from bottom to top to the closed and corner areas of the complex component where the liquid flow is obstructed. Then, lay the wire mesh on the bottom surface of the processing cylinder, start the computer control system and the friction stirring additive system, and complete the program initialization. Lay ordinary steel balls into the processing cylinder until the height of the ordinary steel ball layer reaches the height of the top surface of the base. At the same time, lay temperature-collecting steel balls equipped with thermocouples at equal intervals on the back of the base plate according to the forming path. Open the injection solenoid valve, and the coolant is injected into the processing cylinder through the flow channel of the bottom plate of the processing cylinder until the coolant height reaches the height of the top surface of the base, then close the injection solenoid valve. Then, move the spindle tool head of the additive system above the initial additive point of the substrate, and start rotating the spindle at a speed of ω0.

[0022] Step 2: The spindle tool head of the additive manufacturing system contacts the substrate and performs additive manufacturing layer by layer according to the preset path. The temperature acquisition steel ball obtains the peak temperature T of the base bottom surface in real time and converts this parameter into a voltage signal, which is transmitted to the computer control system through the data acquisition card. The control system compares the peak temperature T of the base bottom surface with the initial preset temperature T0. When T = T0, it displays or outputs a control signal and lays additional metal steel balls with a height of Δh1 into the processing cylinder. Then, temperature acquisition steel balls are laid at intervals around the additive layer. During this process, the stirring friction additive manufacturing does not stop.

[0023] Step 3: The control system continuously obtains and intercepts the average temperatures T2 and T1 (T2>T1) of the two closest temperature acquisition steel balls above and below the liquid level during the stable cooling stage in real time, calculates the difference ΔT between T2 and T1, and calculates the ratio of ΔT to Δt. Δt is a preset time sensitivity factor, and the time sensitivity factor is related to the time intervals of different additive manufacturing stages. When (ΔT / Δt)<a, an output control signal is sent to open the injection solenoid valve to inject coolant with a height of Δh1 into the processing cylinder, and at the same time, metal steel balls with a height of Δh1 are laid. (Note: Since in Step 2, metal steel balls with a height of Δh1 were laid first, so every time Step 3 is experienced, the height of the steel balls is always Δh1 higher than that of the coolant.) At the same time, temperature acquisition steel balls are laid at intervals along the periphery of the additive layer. When (ΔT / Δt)≥a, an output control signal is sent to close the injection solenoid valve, and a is a preset value. When T1>T * , an output control signal is sent to open the injection valve and the output valve simultaneously to partially or completely replace the coolant until T1≤T * ; then, the injection valve and the output valve are closed, and T * is a preset reference temperature.

[0024] Step 4: Whenever the height of the coolant in the processing cylinder differs from the total length of the flow deflector by one flow deflector length, a new flow deflector is connected to the end of the original flow deflector.

[0025] Step 5: The spindle tool head of the additive manufacturing system continues to perform layer-by-layer additive manufacturing according to the preset path, and Steps 3 and 4 are repeated until the forming of the complex component is completed.

[0026] Step 6: After the forming of the complex component is completed, the computer control system outputs a control signal to open the output valve to drain the coolant in the processing cylinder. After the coolant is completely drained, the ordinary steel balls and the temperature acquisition steel balls are taken out, the output valve is closed, the fixture is loosened, and the complex component is taken out.

[0027] Preferably: The diameter of the temperature acquisition steel balls described in Step 1 is the same as that of the ordinary steel balls, and the laying of the steel balls can be manual laying or laying by an additional automatic ball feeding mechanism.

[0028] Preferably: The other liquid injection holes of the bottom plate connected to the flow deflector described in Step 1 are tightened and sealed with bolts, and the liquid injection holes of the bottom plate not connected to the flow deflector are not treated.

[0029] Preferably: The number n of metal steel balls with an additional height of Δh1 laid each time described in Steps 2 and 3 can be determined by n=(1.414×(S - S0)×Δh1) / d0 3 where S is the bottom area of the processing cylinder, S0 is the single-layer additive manufacturing area of the component, and d0 is the diameter of the steel ball.

[0030] Preferably, the temperature acquisition steel balls in steps two and three are always positioned at the middle surface of the additional ordinary steel ball layer.

[0031] Preferably, the coolant injected at an additional height of Δh1 in step three can be controlled by the flow rate V of the injection valve. In this step, the total flow rate V injected into the injection valve can be determined by V = 0.26 × (S - S0) × Δh1, where S is the bottom area of ​​the machining cylinder and S0 is the area of ​​the single-layer additive manufacturing area of ​​the component.

[0032] Preferably, the level of the additional coolant injected in step three is always lower than the additional metal steel ball layer, which can prevent debris or flash from falling directly into the coolant during the additive manufacturing process.

[0033] Preferably, the stable cooling stage in step three refers to the temperature drop stage after the spindle tool head passes through the temperature acquisition steel balls, wherein the temperature acquisition steel balls are laid at intervals around the additive layer and placed close to the additive layer.

[0034] The precision cooling and temperature control device and method for complex component friction stir additive manufacturing designed in this invention have the following advantages:

[0035] (1) By combining metal steel balls and coolant, the disadvantage of the low thermal conductivity of pure coolant compared with pure metal is compensated, and the supercooling of the component structure during the cooling process is improved, so that the heat accumulation of metal components during the layer-by-layer additive process can be discharged more quickly, which can greatly improve the forming speed and the uniformity of the structure.

[0036] (2) Temperature acquisition steel balls were used to collect the temperature above and below the coolant surface, which enabled accurate characterization of the temperature gradient of the additive component. Combined with time-sensitive factors and control system, the purpose of precise cooling and temperature control was achieved.

[0037] (3) By using the base and the flow guide, local cooling of components with complex features such as enclosed and corners can be achieved, which solves the problem of cooling and temperature control in the process of friction stir additive manufacturing of complex components. It is simple to operate, has low hardware cost, and can be extended to a variety of complex structural parts. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a precision cooling and temperature control device for friction stir additive manufacturing of circular components, provided in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the bottom plate structure of the machining cylinder of the present invention.

[0040] Figure 3 This is a schematic diagram of the flow guide structure of the present invention.

[0041] Figure 4The following are schematic diagrams of the base structure of the present invention (a) and examples of several optional shapes of the base plate (b): 31A trapezoid, 31B arc, 31C polygon, and 31D triangle.

[0042] Figure 5 yes Figure 1 Cross-sectional view of the device (AA);

[0043] Explanation of reference numerals in the attached figures:

[0044] 1-Machining cylinder side plate; 2-Machining cylinder bottom plate; 3-Base (including: 31-Base plate; 32-Base support leg); 4-Complex component; 5-Additive system spindle tool head; 7-Coolant; 8-Metal mesh; 9-Base plate; 10-Injection valve; 11-Output valve; 12-Flow guide (121-Flow guide external thread; 122-Flow guide internal thread); 13-Control system; 21-Base plate flow channel; 22-Threaded outlet hole; 23-Fixing hole; 61-Ordinary steel ball; 62-Temperature acquisition steel ball; Detailed Implementation

[0045] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0046] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the attached figures). If the specific posture changes, the directional indication will also change accordingly. Unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0047] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Example 1

[0049] like Figure 1-4As shown, this embodiment provides a precision cooling and temperature control device for complex component friction stir additive manufacturing, which is particularly suitable for multi-layer friction stir additive manufacturing of complex components. It adopts a mixed cooling method of coolant and metal steel balls to improve the supercooling of the additive component, inhibit the growth of grains in the structure during friction stir additive manufacturing, and maintain an equiaxed, fine and dense additive structure. At the same time, through the suspended base 3 and the flow guide 12, the heat accumulation at the closed corners of the complex component is reduced, realizing uniform cooling of all parts of the complex component and improving the forming quality of the component. The precision cooling and temperature control device provided in this embodiment includes four parts: additive system, temperature acquisition system, cooling system, and control system.

[0050] The additive manufacturing system includes a friction stir additive spindle tool head 5, a fixture, and a substrate 9. The friction stir additive spindle tool head 5 is mounted on a parallel robotic arm and can extend into the processing cylinder for additive manufacturing. The substrate 9 is fixed to the base 3 of the processing cylinder by the fixture.

[0051] The temperature acquisition system includes temperature acquisition steel balls 62 equipped with thermocouples. The temperature acquisition steel balls 62 are arranged at equal intervals among ordinary steel balls 61 around the additive component. They are responsible for collecting the real-time temperature of different parts of the additive component and are connected to the data acquisition card through a high-temperature resistant data cable.

[0052] The cooling system includes a machining cylinder, ordinary steel balls 61, coolant 7, injection valve 10, output valve 11, flow guide 12, and wire mesh 8. Coolant 7 is injected into the machining cylinder through injection valve 10 and flows out of the machining cylinder through output valve 11. Flow guide 12 is connected to the inlet hole at the bottom of the machining cylinder via a screw hole and supplies coolant from bottom to top to areas with poor liquid flow, such as enclosed sections and corners of complex components. Wire mesh 8 is laid on the bottom surface of the machining cylinder to prevent the ordinary steel balls 61 from blocking the outlet hole at the bottom surface of the machining cylinder. The container is a cuboid with dimensions of 600mm×500mm×500mm. The side plate 1 and bottom plate 2 of the processing cylinder are assembled by a dovetail groove with a sealing gasket. The height of the base support leg inside the processing cylinder is 50mm. The diameter of the threaded liquid outlet hole of the bottom plate 2 is 8mm. The ordinary steel ball 61 is made of stainless steel and has a diameter of 5mm. The coolant 7 is propylene glycol. The injection valve 10 and the output valve 11 are solenoid valves with a liquid flow control module. The length of the guide 12 is 50mm. The size of the metal wire mesh 8 is 3mm.

[0053] The control system 13 includes a data acquisition card and a computer control system. The thermocouple, solenoid valve, and communication terminals of the stirring friction amplification spindle tool head 5 of the temperature acquisition steel ball 62 are respectively connected to the data acquisition card. The data acquisition card communicates with the computer control system through a USB interface. The data acquisition card is responsible for converting input and output signals, and the computer control system is responsible for signal processing.

[0054] Example 2

[0055] This embodiment provides a precise cooling and temperature control method for complex component friction stir additive manufacturing. It includes using the precise cooling and temperature control device provided in Embodiment 1 for cooling, and additive forming of TC4 titanium alloy ring component 4. The ring component 4 has an outer diameter of 140mm, an inner diameter of 60mm, and a height of 300mm. Due to the low thermal conductivity of titanium alloy and the narrow inner diameter area of ​​the ring component 4, which is closed, heat accumulation is relatively serious during the cooling process, requiring additional cooling measures.

[0056] Specifically, the precise cooling and temperature control method provided in this embodiment includes the following steps:

[0057] Step 1: Select several base plates 31A with trapezoidal surfaces, and connect them end-to-end to form an approximately circular base 3, as shown below. Figure 5 As shown, the base support leg 32 is installed to the bottom surface of the processing cylinder by bolt connection. Then, a 10mm thick annular substrate 9 with inner and outer diameters of 50mm and 150mm respectively is fixed to the base 3 using a clamp. The TC4 titanium alloy annular component 4 can be added layer by layer on the annular substrate 9. Then, nine sections of guide vanes 12 are installed on the bottom surface of the processing cylinder in a 3×3 even arrangement within the center of the annular substrate 9. Next, a metal wire mesh 8 is laid on the bottom surface of the processing cylinder. The computer control system and the stirring friction additive manufacturing system are started, and the program initialization is completed. Ordinary steel balls 61 are automatically laid into the processing cylinder by an external ball feeder until the height of the ordinary steel ball layer 61 reaches the top surface of the base 3. When the ordinary steel ball layer 61 is about to reach the top surface of the base 3, four temperature-sensing steel balls 62 equipped with thermocouples are laid equidistantly along a circumference with a radius of 100mm on the back of the base 3. The specific positions of the four temperature-sensing steel balls 62 equipped with thermocouples in this step are shown below. Figure 5 As shown. Open the injection solenoid valve, and coolant 7 is injected into the machining cylinder through the flow channel of the machining cylinder bottom plate 2 and the guide 12 until the coolant 7 reaches the top surface of the base 3. Then close the injection solenoid valve (at this time, the four temperature acquisition steel balls 62 equipped with thermocouples on the back of the base 3 are already below the liquid surface). Then move the additive manufacturing system spindle tool head 5 above the initial additive point of the substrate 9, and the spindle starts to rotate at a speed of 350 rpm.

[0058] Step 2: The spindle tool head 5 of the additive manufacturing system contacts the substrate 9, and additive manufacturing is performed layer by layer according to a preset path. The temperature acquisition steel ball 62 continuously obtains the peak temperature T on the back surface of the base 3 in real time, and converts this parameter into a voltage signal and transmits it into the computer control system through a data acquisition card. The control system 13 compares the peak temperature T on the back surface of the base 3 with the initial preset temperature of 180 °C. When T = 180 °C, it displays or outputs a control signal to additionally lay metal steel balls with a height of 30 mm in the processing cylinder, approximately 2,800 metal steel balls. Then, two circles of temperature acquisition steel balls 62 are laid equidistantly along the inner and outer diameters of the additive manufacturing layer parallel to the temperature acquisition steel balls in Step 1 (4 for each circle, a total of 8 for the inner and outer circles, all above the liquid level). The temperature acquisition steel balls are placed closely against the additive manufacturing layer, and the previously laid temperature acquisition steel balls are retained, and friction stir additive manufacturing does not stop during this process.

[0059] Step 3: The control system 13 continuously obtains the average temperatures T2 and T1 of the two closest circles of temperature acquisition steel balls above and below the liquid level (a row of temperature acquisition steel balls above the liquid level, 4 near the inner and outer diameters respectively, a total of 8, whose average temperature is T2. Similarly, the average temperature of a row of temperature acquisition steel balls below the liquid level is T1, T2 > T1; Note: The row of temperature acquisition steel balls below the liquid level when Step 3 is first executed is the layer of temperature acquisition steel balls laid in Step 1. When Step 3 is executed for the second time after one execution of Step 3, the temperature acquisition steel balls below the liquid level become the layer of temperature acquisition steel balls laid in Step 2, and so on). The specific positions of the temperature acquisition steel balls in this step are as Figure 1 shown. And calculate the ratio of the difference ΔT between T2 and T1 to Δt, where Δt is a preset time sensitivity factor, and in this embodiment, Δt = 31.4; when (ΔT / Δt) < a, output a control signal to open the injection solenoid valve to additionally inject coolant 7 with a height of 30 mm into the processing cylinder, that is, inject 2.152 L of coolant 7 through the injection valve 10, and additionally lay metal steel balls with a height of 30 mm. Then, two circles of 4 temperature acquisition steel balls 62 are laid equidistantly along the inner and outer diameters of the additive manufacturing layer (4 for each circle, a total of 8 for the inner and outer circles, all above the liquid level). The temperature acquisition steel balls are placed closely against the additive manufacturing layer, and the previously laid temperature acquisition steel balls are retained, and friction stir additive manufacturing does not stop during this process. When (ΔT / Δt) ≥ a, output a control signal to close the injection solenoid valve, where a is a preset value, and in this embodiment, a = 0.4777; when T1 > T*, output a control signal to simultaneously open the injection valve 10 and the output valve 11 to partially or completely replace the coolant 7 (to prevent the coolant temperature from being too high) until T1 ≤ T*, then close the injection valve 10 and the output valve 11, where T* is a preset reference temperature, and in this embodiment, T* = 50 °C.

[0060] Step 4: Whenever the total height of the coolant 7 in the processing cylinder differs from the total length of the guide tube by the length of one guide tube 12, a new guide tube is connected to the end of the original guide tube.

[0061] Step 5: The spindle tool head 5 of the additive manufacturing system continues to add material layer by layer according to the preset path, repeating steps 3 and 4 until the complex component 4 is formed.

[0062] Step Six: After the complex component 4 is formed, the computer control system outputs a control signal, the output valve 11 opens, and the coolant 7 in the processing cylinder is discharged. After the coolant 7 is completely drained, the ordinary steel ball 61 and the temperature acquisition steel ball 62 are taken out, the output valve 11 is closed, the clamp is released, and the TC4 titanium alloy ring component 4 is taken out.

[0063] The above embodiments, by combining metal steel balls and coolant, overcome the disadvantage of the low thermal conductivity of pure coolant compared to pure metal, thereby improving the supercooling of the TC4 titanium alloy ring component during the cooling process. This allows for faster heat dissipation during the layer-by-layer additive manufacturing process, significantly increasing forming speed and microstructure uniformity. Furthermore, the use of temperature-sensing steel balls to collect temperatures above and below the coolant surface enables precise characterization of the temperature gradient in the additive component. Combined with a time-sensitive factor and control system, precise cooling and temperature control are achieved. Additionally, the elevated base and several flow guides allow the coolant to enter the closed ring region from the bottom up through the flow guides, significantly improving localized heat accumulation. The above device and method solve the problem of cooling and temperature control in the friction stir additive manufacturing process of complex components. It is simple to operate, has low hardware costs, and can be extended to various complex structural parts.

[0064] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for friction stir additive manufacturing based on a precise cooling temperature control device for complex component friction stir additive manufacturing, characterized in that, The complex component friction stir additive manufacturing precision cooling temperature control device comprises an additive system, a temperature acquisition system, a cooling system and a control system. The additive system comprises an additive system spindle tool head, a clamp and a base plate, and the base plate is fixed on the base of the processing cylinder through the clamp. The temperature acquisition system comprises temperature acquisition steel balls equipped with thermocouples, and a plurality of temperature acquisition steel balls are arranged at equal intervals in the ordinary steel balls around the additive component to collect the real-time temperature of different parts of the additive component and are connected to the data acquisition card through high-temperature resistant data lines. The cooling system comprises a processing cylinder, ordinary steel balls, cooling liquid, an injection valve, an output valve, a flow guide and a metal wire mesh. The method comprises the following steps: Step one: according to the shape characteristics of the complex component to be additive shaped, select the appropriate base plate combination, and install into the base in the processing cylinder, the surface of the base plate with the thickness of d is fixed on the base by clamp, then according to the plane position of the closed corner of the complex component, connect one end of the flow guide to the bottom plate of the processing cylinder, the flow guide can send the cooling liquid from bottom to top to the part where the liquid flow is not smooth in the closed corner of the complex component, then lay the metal wire mesh on the bottom surface of the processing cylinder, start the computer control system and the friction stir additive system, complete the program initialization; put the ordinary steel ball into the processing cylinder until the height of the ordinary steel ball layer reaches the height of the top surface of the base, at the same time, lay the temperature collection steel ball equipped with thermocouple equidistantly on the back surface of the base plate according to the forming path, open the injection valve, the cooling liquid is injected into the processing cylinder through the flow channel of the bottom plate of the processing cylinder, close the injection valve after the cooling liquid height reaches the height of the top surface of the base; then move the main shaft tool head of the additive system above the initial additive point of the base plate, start rotating the main shaft at the speed of 0 ω 0 rpm; Step two: the additive system spindle tool head contacts the base plate, and additive manufacturing is performed layer by layer along the preset path, the temperature acquisition steel balls acquire the peak temperature T of the base plate bottom surface in real time, and the parameter is converted into a voltage signal and transmitted to the computer control system through the data acquisition card, the control system compares the peak temperature T of the base plate bottom surface with the initial preset temperature T0, and when T = T0, a control signal is displayed or output, and metal steel balls with an additional height of Δh1 are additionally laid in the processing cylinder, and temperature acquisition steel balls are laid along the periphery of the additive layer at intervals, and the friction stir additive manufacturing process is not stopped in this process. Step three: the control system acquires and intercepts the average temperature T2, T1 (T2>T1) of the temperature collection steel balls of the most similar two circles of the liquid surface in the stable cooling stage in real time, calculates the difference AT between T2 and T1, and calculates the size of the ratio of AT and At, At is a pre-set time sensitive factor, the time sensitive factor is related to the time interval of different additive stages; when (AT / At) <a, output the control signal to open the injection valve, inject the cooling liquid with a height of Ah1 into the processing cylinder, and at the same time, lay the metal steel balls with a height of Ah1, and at the same time, lay the temperature collection steel balls along the periphery of the additive layer; when (AT / At) ≥a, output the control signal to close the injection valve, a is a pre-set value; when T1>T * , output the control signal to open the injection valve and the output valve at the same time, and replace part or all of the cooling liquid until T1≤T * , close the injection valve and the output valve, T * is a pre-set reference temperature; Step four: when the height of the cooling liquid in the processing cylinder is different from the total length of the flow guide by one flow guide length, a new flow guide is connected to the end of the original flow guide. Step five: the additive system spindle tool head continues to perform additive manufacturing layer by layer along the preset path, and steps three and four are repeated until the complex component is formed. Step six: after the complex component is formed, the computer control system outputs a control signal, the output valve is opened, the cooling liquid in the processing cylinder is discharged, the ordinary steel balls and the temperature acquisition steel balls are taken out after the cooling liquid is completely emptied, the output valve is closed, the clamp is loosened, and the complex component is taken out.

2. The method of claim 1, wherein, In step one, the diameter of the temperature acquisition steel ball is the same as that of the ordinary steel ball, and the steel balls are laid manually or by an additional automatic ball feeding mechanism.

3. The method of claim 1, wherein, The number n of metal steel balls with an additional laying height of Ah1 in each of the second and third steps is n = (1.414 x (S-S0) x Ah1) / d0 3 determined, where S is the processed cylinder bottom area, S0 is the component single layer additive area, and d0 is the steel ball diameter.

4. The method of claim 1, wherein, In step three, the injection of the cooling liquid with an additional height of Δh1 can be controlled by the flow rate V of the injection valve, and the total injection flow rate V of the injection valve in this step can be determined by V = 0.26 × (S-S0) × Δh1, wherein S is the bottom area of the processing cylinder and S0 is the single-layer additive area of the component.

5. The method of claim 1, wherein: The processing cylinder is composed of a modular special side plate, a bottom plate and a base.

6. The method of claim 5, wherein: The modular special side plate and bottom plate can be assembled and connected by dovetail groove or sliding rail.

7. The method of claim 5, wherein: The bottom plate has a through flow channel, both ends of which can be sealed according to requirements, the flow channel is communicated with the inside of the processing cylinder through a threaded liquid outlet hole, and the surface of the bottom plate in the processing cylinder has a fixing hole, and the diameter of the liquid outlet hole is 5-10 mm.

8. The method of claim 1, wherein: The base is composed of support legs and a base plate, the support legs are connected with the bottom surface of the processing cylinder through bolts and fixing holes, the height of the support legs is 50-200 mm, and the base plate is in the shape of a rectangle, a trapezoid, a triangle or a rhombus, and can be arranged and combined to form a support base required by a complex component.

9. The method of claim 1, wherein: The ordinary steel ball has a diameter of 1.2-10 mm and is made of stainless steel, bearing steel or carbon steel.

10. The method of claim 1, wherein: The flow guide is a hollow pipe with open ends, one end of which is provided with external threads and can be connected with the threaded liquid outlet hole on the bottom surface of the processing cylinder.

11. The method of claim 1, wherein: The mesh of the metal wire is smaller than the diameter of the steel ball, preventing the ordinary steel ball from blocking the liquid outlet hole on the inner wall of the processing cylinder.

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