A control method for a friction stir welding device

Abstract

The present invention provides a control method for a friction stir welding device. By precisely controlling the temperature distribution in each area during the welding process, the problem that it is difficult to precisely adjust the cooling rate by the traditional water cooling method is overcome. The method includes a welding table, a positioning fixture, a welding part, and a temperature reduction mechanism. The temperature reduction mechanism performs gradient cooling on the weld and the areas on both sides of the plate through multiple temperature reduction channels in a box body connected to the welding part. Multiple injectors and fans are connected to the temperature reduction channels to precisely adjust the injection amount of the coolant and the flow rate of the air flow. Moreover, the controller calculates the target temperature reduction amplitude of the weld and the heat dissipation areas on both sides thereof according to the environmental parameters, the target parameters of the plate, and the control parameters of the stirring head, and controls the injection amount of the coolant and the flow rate of the air flow in each channel based on this, so as to avoid too large a temperature difference between the weld and the areas on both sides thereof, prevent welding defects such as microcracks and deformation caused by uneven thermal stress during the welding process, and significantly improve the welding quality and joint strength.

Description

Technical Field

[0001] The present invention relates to a friction stir welding device, and in particular to a control method for a friction stir welding device. Background Art

[0002] Welding technology is widely used in the processing and manufacturing of metal materials. Especially in industries such as automobiles, aerospace, ships, and electronic devices, welding technology plays a crucial role. In these industries, welded components usually need to withstand complex working environments such as high temperature and stress. Therefore, the quality of the welded joint is of utmost importance. With the continuous development of welding processes, friction stir welding (FSW), as a new type of solid-state welding technology, has been increasingly applied to the welding of light alloys and high-strength steels due to its advantages such as low deformation, low residual stress, and no melting. To ensure welding quality, it is crucial to control the temperature distribution during the welding process.

[0003] In traditional welding technologies, a water cooling system is usually widely used as a temperature control means. The coolant flows through the preset cooling pipes to the welding area, thereby taking away the heat from the welding area. The coolant of the water cooling system usually covers the surface of the welding area in a relatively uniform manner, and the temperature is reduced by overall immersion of the plate to ensure that the temperature is stable within a certain range.

[0004] However, during the friction stir welding process, the heat source is concentrated at the welding site, and the temperature of the weld area is much higher than that of the surrounding area. This results in an obvious thermal gradient during the welding process. The cooling rate of the areas on both sides of the weld is usually relatively fast, which is likely to cause a large temperature difference between the weld and the areas on both sides. When the areas on both sides of the weld contract during the cooling process, this temperature difference is likely to generate a large tensile stress on the weld. Excessive temperature difference and stress unevenness may lead to the formation of microcracks, deformation of the welded joint, and even affect the overall welding quality and the strength of the structure. Therefore, it is urgent to propose a control method for a friction stir welding device to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a control method for a friction stir welding device that realizes precise temperature reduction control of the welding area and its surrounding areas by controlling the injection amount of the coolant, the air flow rate, and the layout of the cooling channels, thereby achieving gradient cooling of the weld and its surrounding areas. And this control method ensures the balance of the cooling process by calculating the continuous cooling duration, thereby effectively avoiding problems such as cold cracks and excessive thermal stress caused by excessive temperature difference.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows: A control method for a friction stir welding device is used to weld the seams of two plate members. The friction stir welding device includes a welding part controlled to operate and a cooling mechanism that moves with the welding part. The cooling mechanism includes a box body, a number of controlled injectors, and a number of controlled air blowers. One side of the box body is provided with a fitting plane that fits against the side of the plate member when the cooling mechanism is in the working state, and a number of cooling channels are constructed at the fitting plane. The cooling channel in the middle is arranged opposite to the weld of the plate member, and the remaining cooling channels are evenly distributed on both sides of the weld of the plate member. Moreover, a number of injectors and a number of air blowers are in one-to-one correspondence and communication with a number of cooling channels respectively to inject coolant and introduce air flow into each cooling channel respectively.

[0007] The control method includes:

[0008] Obtain the environmental parameters and the target parameters of the plate member, and determine the target parameters and control parameters of the stirring head according to the target parameters of the plate member.

[0009] Determine the target cooling amplitude of the weld of the plate member and each heat dissipation area on both sides of the weld according to the environmental parameters, the target parameters of the plate member, the target parameters of the stirring head, and the control parameters of the stirring head. And each heat dissipation area corresponds to each cooling channel one by one.

[0010] Determine the continuous cooling duration of a single position of the weld according to the control parameters of the stirring head and the box body size parameters.

[0011] Determine the target injection volume of the coolant and the target flow rate of the air flow in each cooling channel according to the continuous cooling duration and the target cooling amplitude of the weld of the plate member and each heat dissipation area on both sides of the weld.

[0012] Control the operation of the friction stir welding device according to the control parameters of the stirring head, the size parameters of each cooling channel, the continuous cooling duration, the target injection volume of the coolant in each cooling channel, and the target flow rate of the air flow.

[0013] Preferably, the welding part further includes a stirring head that rotates controllably.

[0014] A number of liquid inlets, a number of air inlets, a number of air outlets, and a number of liquid inlets that are in one-to-one correspondence and communication with a number of cooling channels are provided on the surface of the box body. A number of liquid inlets are connected to a number of injectors one by one, and a number of air inlets are connected to a number of air blowers one by one.

[0015] The friction stir welding device further includes:

[0016] A thermometer for detecting the environmental temperature.

[0017] A welding table including a material supporting plane for placing the plate member.

[0018] A positioning fixture, connected to the soldering station, and the positioning fixture controllably fixes the plate placed on the material supporting plane on the material supporting plane.

[0019] A controller, connected to each injector, each blower, the thermometer and the welding part, to control the operation of each injector, each blower and the welding part.

[0020] Preferably, obtain the environmental parameters and the target parameters of the plate, and determine the target parameters of the stirring head and the control parameters of the stirring head according to the target parameters of the plate, including:

[0021] Obtain the environmental temperature, the material of the plate and the thickness of the plate.

[0022] Determine the material of the stirring head according to the material of the plate.

[0023] Determine the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate according to the material and thickness of the plate.

[0024] Preferably, determine the target temperature reduction amplitude of the weld of the plate and each heat dissipation area on both sides of the weld according to the environmental parameters, the target parameters of the plate, the target parameters of the stirring head and the control parameters of the stirring head, and each heat dissipation area corresponds to each cooling channel one by one, including:

[0025] Determine the welding temperature of the weld of the plate and each heat dissipation area on both sides of the weld according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate, and each heat dissipation area corresponds to each cooling channel one by one.

[0026] Determine the corresponding target temperature reduction amplitude of the weld of the plate and each heat dissipation area on both sides of the weld according to the welding temperature of the weld of the plate and each heat dissipation area on both sides of the weld and the environmental temperature.

[0027] Preferably, determine the welding temperature of the weld of the plate and each heat dissipation area on both sides of the weld according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate, and each heat dissipation area corresponds to each cooling channel one by one, including:

[0028] Determine the weld temperature of the plate during welding according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate.

[0029] Determine the influence range of the weld temperature on both sides of the weld of the plate according to the weld temperature and the material of the plate.

[0030] Divide the range of the weld of the plate and the areas on both sides of the weld affected by the weld temperature into several heat dissipation areas, and determine the welding temperature of each heat dissipation area, and each heat dissipation area corresponds to each cooling channel one by one when the cooling mechanism is in the working state.

[0031] Preferably, determining the duration of continuous temperature drop at a position of a weld seam according to the control parameters of the stirring head and the size parameters of the box body includes:

[0032] Obtaining the corresponding length of the cooling channel in the extending direction of the plate weld seam when the cooling mechanism is in the working state.

[0033] Determining the duration of continuous temperature drop at a single position of the weld seam according to the length of the cooling channel in the extending direction of the plate weld seam and the moving speed of the stirring head along the direction of the plate weld seam.

[0034] Preferably, determining the target injection amount of the coolant and the target flow rate of the air flow in each cooling channel according to the duration of continuous temperature drop, the target temperature drop amplitude of the plate weld seam and each heat dissipation area on both sides of the weld seam includes:

[0035] Obtaining the heat exchange area of the orthographic projection contour of each cooling channel on the side of the plate away from the welding table when the cooling mechanism is in the working state.

[0036] Determining the target injection amount of the coolant and the target flow rate of the air flow in each cooling channel according to the heat exchange area of each cooling channel and the duration of continuous temperature drop.

[0037] Preferably, controlling the operation of the friction stir welding device according to the control parameters of the stirring head, the size parameters of each cooling channel, the target injection amount of the coolant and the target flow rate of the air flow in each cooling channel. This step includes:

[0038] Controlling the operation of the friction stir welding device according to the control parameters of the stirring head, the size parameters of each cooling channel, the target injection amount of the coolant and the target flow rate of the air flow in each cooling channel, including:

[0039] Determining the total injection height of the coolant in the cooling channel according to the target injection amount of the coolant in the cooling channel and the heat exchange area of the corresponding cooling channel.

[0040] Determining the single injection amount, the interval duration and the total injection times of the coolant in the cooling channel according to the total injection height of the coolant in the cooling channel, the duration of continuous temperature drop and the target flow rate of the air flow in the cooling channel.

[0041] Controlling the operation of each injector according to the single injection amount, the interval duration and the total injection times of the coolant, and controlling the operation of each blower according to the target flow rate of the air flow and the interval duration.

[0042] Preferably, the friction stir welding device further includes:

[0043] A plurality of nozzles, which are arranged inside each cooling channel in a one-to-one correspondence, and the plurality of nozzles are connected to the liquid inlets of the plurality of cooling channels. The nozzles are configured to evenly lay the coolant injected into the cooling channel on the surface of the plate when the injector injects the coolant into the corresponding cooling channel.

[0044] Advantages of the embodiments in the present invention:

[0045] Due to the adoption of the control method of the friction stir welding device, the injection amount of the coolant and the flow rate of the air flow can be accurately adjusted according to the temperature distribution during the welding process and the thermal gradient on both sides of the weld, avoiding the problem that the traditional water cooling method cannot accurately control the cooling rate, and then effectively solving the problem of excessive temperature difference during the welding process, reducing the risk of defects such as microcracks and deformation in the welded joint, and improving the welding quality and the strength of the joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic top view showing the alignment state of the cooling mechanism and the weld during the operation of the welding part according to an embodiment of the present invention.

[0047] Figure 2 A schematic front view showing the alignment state of the cooling mechanism and the weld during the operation of the welding part according to an embodiment of the present invention.

[0048] Figure 3 A schematic rear view showing the alignment state of the cooling mechanism and the weld during the operation of the welding part according to an embodiment of the present invention.

[0049] Figure 4 A schematic structural diagram showing the cooling mechanism according to an embodiment of the present invention.

[0050] Figure 5 A schematic front sectional view showing the cooling mechanism according to an embodiment of the present invention.

[0051] Figure 6 A schematic rear sectional view showing the cooling mechanism according to an embodiment of the present invention.

[0052] Figure 7 A schematic flow chart showing the control method for the friction stir welding device according to an embodiment of the present invention.

[0053] Figure 8 Showing the present invention Figure 7 A schematic flow chart showing the method for determining the rotational speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate in step S100 shown in the present invention.

[0054] Figure 9 Showing the present invention Figure 7 A schematic flow chart showing the method for determining the target temperature reduction amplitude of each heat dissipation area on both sides of the weld and the weld in step S200 shown in the present invention.

[0055] Figure 10 Showing the present invention Figure 9Schematic flowchart of the method for determining the welding temperature at each heat dissipation area in step S210 shown therein.

[0056] Figure 11 Shows the present invention Figure 7 Schematic flowchart of the method for determining the duration of continuous temperature reduction in step S300 shown therein.

[0057] Figure 12 Shows the present invention Figure 7 Schematic flowchart of the method for determining the target injection volume of the coolant and the target flow rate of the air flow in step S400 shown therein.

[0058] Figure 13 Shows the present invention Figure 7 Schematic flowchart of the method for controlling the injector and the fan in step S500 shown therein.

[0059] Figure 14 Is a schematic structural diagram of a friction stir welding device showing an embodiment of the present invention.

[0060] Wherein: 10, welding table; 110, material supporting plane; 20, positioning fixture; 30, welding part; 310, stirring head; 40, temperature reduction mechanism; 410, box body; 411, fitting plane; 412, temperature reduction flow channel; 413, liquid inlet; 414, air inlet; 415, air outlet; 50, plate; 510, weld seam. Detailed implementation manners

[0061] The following combines the drawings and embodiments to further describe in detail the specific implementation manners of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0062] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as limiting the protection scope of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0063] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0064] As Figures 1 to 6 and Figure 14 shown, in a preferred embodiment of the present application, a friction stir welding device is provided for welding the seams of two plates 50. The friction stir welding device includes a welding table 10, a positioning fixture 20, a welding part 30, and a cooling mechanism 40. Among them, the welding table 10 includes a material-bearing plane 110. The positioning fixture 20 is connected to the welding table 10 to fix the plate 50 at the material-bearing plane 110 during the welding process. The welding part 30 moves under control. The welding part 30 includes a stirring head 310 that rotates under control.

[0065] Among them, after the welding table 10 is installed, the material-bearing plane 110 is parallel to the horizontal plane to prevent the plate 50 placed on the material-bearing plane 110 from slipping. The positioning fixture 20 generally includes a clamping part and a driver, etc. The clamping part is configured to be adapted to the plate 50. The clamping part is movably installed on the welding table 10, and the clamping part can rotate and / or move relative to the welding table 10, so that the abutting surface of the clamping part can abut against the plate 50, and the plate 50 on the material-bearing plane 110 is limited and fixed with the cooperation of a plurality of clamping assemblies or other limiting members fixed on the material-bearing plane 110. The driver can be selected from a cylinder or an electric push cylinder, etc. The welding mechanism is composed of a displacement mechanism and the welding part 30. The displacement mechanism can be selected from a displacement module composed of several electric sliders and guide rails, or a robotic arm, etc., which should be determined according to the actual use requirements. The welding part 30 is arranged at the moving end of the displacement mechanism to achieve flexible position transformation. The welding part 30 at least includes a motor, a coupling, a rotating shaft, and a fixture for clamping the stirring head 310. The rotating shaft is connected to the output shaft of the motor through the coupling. The fixture is installed on the rotating shaft to rotate synchronously with the rotating shaft, and the fixture is usually detachable to facilitate the replacement of the stirring head 310.

[0066] To improve the quality of the weld 510 and ensure that the temperature in the weld 510 area can drop to the target temperature synchronously with the surrounding area, thus avoiding stress concentration and microcrack problems caused by excessive temperature difference, the friction stir welding device further includes a cooling mechanism 40. The cooling mechanism 40 is connected to the welding part 30 to move along with the welding part 30. The cooling mechanism 40 includes a box body 410. One side of the box body 410 is a fitting plane 411. When the cooling mechanism 40 is working, the fitting plane 411 fits with the side of the plate 50 facing away from the welding table 10 and fixed on the material-bearing plane 110 through the positioning mechanism, so as to cooperate with the subsequent coolant and air flow to cool the plate 50. A plurality of cooling channels 412 are formed on the side of the box body 410 where the fitting surface is located. A plurality of liquid inlets 413, a plurality of air inlets 414 and a plurality of air outlets 415 are also formed on the surface of the box body 410. Each liquid inlet 413 is in one-to-one correspondence and communication with each cooling channel 412, and the same is true for each air inlet 414 and each air outlet 415, which are in one-to-one correspondence and communication with each cooling channel 412. Moreover, when the cooling mechanism 40 is in the working state, one of the cooling channels 412 in each cooling channel 412 is aligned with the weld 510 when the fitting plane 411 fits with the side of the plate 50 facing away from the welding table 10, and the remaining cooling channels 412 are evenly divided into two groups and symmetrically arranged on both sides of the weld 510 of the plate 50.

[0067] Specifically, the box body 410 is embodied as a shell approximately in the shape of a cuboid in a specific manner. One side of the box body 410 is a plane, which is the abutting plane. The cooling channels 412 formed on this side are recessed towards the inside of the box body 410 to form a number of flat cuboid spaces inside the box body 410, and the cooling channels 412 will leave openings at the abutting plane. The cooling channels 412 are arranged parallel to each other, and the cooling channels 412 are perpendicular to the abutting plane and parallel to one side of the box body 410. When the cooling mechanism 40 is in the working state, each cooling channel 412 is perpendicular to the side of the plate 50 facing away from the welding table 10. The channel aligned with the weld 510 is defined as the first channel, and the remaining cooling channels 412 are defined as the second channels. Moreover, the intervals between the cooling channels 412 should be as narrow as possible to avoid the area corresponding to the interval on the fitting plane 411 being too large and affecting heat dissipation and cooling. And each cooling channel 412 has a separate liquid inlet 413, a separate air inlet 414 and a separate air outlet 415 corresponding to it. The air outlets 415 in each cooling channel 412 are all formed on the side of the box body 410 in the forward direction when the cooling mechanism 40 is in the working state, while the air inlets 414 are formed on the side of the box body 410 facing away from the forward direction. The liquid inlets 413 can be formed on the side of the box body 410 facing away from the plate 50, that is, the top of the box body 410.

[0068] To control the injection volume of the coolant and the flow rate of the air flow, the cooling mechanism 40 further includes a plurality of injectors (not shown in the figure), a plurality of fans (not shown in the figure), a thermometer, and a controller. Each injector is connected to each liquid inlet 413 in a one-to-one correspondence, and each injector is connected to the controller to achieve quantitative injection. Each fan is connected to each air inlet 414 in a one-to-one correspondence, and each fan is also connected to the controller to introduce an air flow with a specific flow rate into each cooling channel 412. The thermometer is connected to the controller to transmit the ambient temperature collected by the thermometer to the controller. Moreover, the controller is also connected to the displacement module or the robotic arm to control the moving speed (welding speed) of the welding part 30 and the rotating speed of the stirring head 310.

[0069] However, although the above-mentioned friction stir welding device can cool the weld 510 and the two sides of the weld 510 respectively, how to ensure that the weld 510 and the areas on both sides of the weld 510 can be sufficiently cooled at the welding speed so that the weld 510 and the areas on both sides of the weld 510 can reach the target temperature after the box body 410 passes by the weld 510, a control method applicable to the above-mentioned friction stir welding device needs to be further proposed, such as Figure 7 shown, to meet the gradient cooling requirements of the weld 510 and the areas on both sides. The specific control method is as follows:

[0070] S100: Obtain the ambient parameters and the target parameters of the plate 50, and determine the target parameters and control parameters of the stirring head 310 according to the target parameters of the plate 50.

[0071] S200: Determine the target cooling amplitude of each heat dissipation area on the weld 510 and the two sides of the weld 510 of the plate 50 according to the ambient parameters, the target parameters of the plate 50, the target parameters of the stirring head 310, and the control parameters of the stirring head 310, and each heat dissipation area corresponds to each cooling channel 412 in a one-to-one correspondence.

[0072] S300: Determine the continuous cooling duration at a position of the weld 510 according to the control parameters of the stirring head 310 and the size parameters of the box body 410.

[0073] S400: Determine the target injection volume of the coolant and the target flow rate of the air flow in each cooling channel 412 according to the continuous cooling duration and the target cooling amplitude of each heat dissipation area on the weld 510 and the two sides of the weld 510 of the plate 50.

[0074] S500: Control the operation of the friction stir welding device according to the control parameters of the stirring head 310, the size parameters of each cooling channel 412, the continuous cooling duration, the target injection volume of the coolant in each cooling channel 412, and the target flow rate of the air flow.

[0075] Among them, the step of "S100: Obtain the environmental parameters and the target parameters of the plate 50, and determine the target parameters and control parameters of the stirring head 310 according to the target parameters of the plate 50" is as Figure 8 shown, and includes:

[0076] S110: Obtain the environmental temperature, the material of the plate 50, and the thickness of the plate 50.

[0077] S120: Determine the material of the stirring head 310 according to the material of the plate 50.

[0078] S130: Determine the rotation speed of the stirring head 310 and the moving speed of the stirring head 310 along the weld 510 direction of the plate 50 according to the material and thickness of the plate 50.

[0079] Among them, the environmental parameter is the environmental temperature, which can be obtained through a thermometer or a temperature sensor.

[0080] The target parameters of the plate 50 are the material of the plate 50 and the thickness of the plate 50, which can be specifically obtained from the supplier or through detection, and will not be elaborated here. The material and thickness of the plate 50 are both related to the welding temperature during welding of the weld 510. Moreover, the material of the plate 50 is also related to the selection of the material of the stirring head 310.

[0081] Specifically:

[0082] Determine the material category of the plate 50, and clarify the base metal type of the plate 50 (such as aluminum, copper, titanium) and its alloy characteristics.

[0083] Analyze the thermal conductivity of the plate 50, and judge the heat transfer efficiency during the welding process according to the thermal conductivity of the metal. For high thermal conductivity materials (such as aluminum alloy), it is necessary to select a stirring head 310 material with good heat resistance to prevent the temperature of the weld 510 from being insufficient due to rapid heat dissipation. For low thermal conductivity materials (such as titanium alloy), the stirring head 310 material needs to have higher hardness and wear resistance. Moreover, it is also necessary to evaluate the melting point and welding temperature range of the material to ensure that the melting point of the stirring head 310 material is higher than the welding temperature to avoid deformation or melting of the stirring head 310 during the high-temperature welding process.

[0084] After determining the material of the stirring head 310 according to the above conditions, it is also necessary to verify it through experiments. The data in actual applications can be referred to, such as the performance of the stirring head 310 when welding different materials, or confirm the stability and applicability of the selected stirring head 310 material during the actual welding process through tests.

[0085] Therefore, through the above steps, the appropriate material of the stirring head 310 can be accurately selected according to the material of the plate 50. For example, tool steel can be selected as the material of the stirring head 310 when welding aluminum alloy, and superhard alloy can be selected as the material of the stirring head 310 when welding titanium alloy.

[0086] After the material of the plate 50, the thickness of the plate 50, and the material of the stirring head 310 are determined, in order to ensure good quality of the weld 510, the optimal rotation speed range of the stirring head 310 and the optimal moving speed range of the stirring head 310 along the weld 510 direction of the plate 50 (optimal welding speed range) can be determined by means such as looking up tables or conducting tests.

[0087] Specifically:

[0088] According to the determined thickness of the plate 50 (such as the plate thickness is less than 5 mm, the plate thickness is between 5 mm and 10 mm, and the plate thickness is greater than 10 mm).

[0089] Evaluate the heat input requirements. The heat input required for welding should be analyzed according to the thickness of the plate 50 and the material of the plate 50 (the heat input is determined by the combined action of the rotation speed of the stirring head 310 and the welding moving speed). Specifically, the heat required for welding of various common plate materials in various common plate thicknesses can be determined through repeated tests with a single variable controlled (the range of the rotation speed of the stirring head 310 and the range of the welding speed). The following are the specific test designs and specific implementation steps:

[0090] The purpose of this test is to find the optimal welding parameters (rotation speed of the stirring head 310 and welding speed) for plates 50 with different materials and thicknesses by adjusting the rotation speed of the stirring head 310 and the welding speed, so as to ensure the maximization of welding quality.

[0091] The welding materials can be various common metal plate materials, such as: aluminum alloy (such as 6061), titanium alloy (such as Ti-6Al-4V), and stainless steel (such as 304 stainless steel), etc.

[0092] The thickness of the plate 50 starts from the minimum thickness and gradually increases. For example, 2 mm, 5 mm, 10 mm.

[0093] The friction stir welding equipment includes a stirring head 310, a welding table 10, a motor, a welding positioning fixture 20, etc.

[0094] The measuring tools include a thermometer (to ensure stable ambient temperature), a microscope (for microscopic structure inspection), and mechanical testing equipment (for testing the strength of the weld 510).

[0095] The test steps include:

[0096] Step 1: Determine the material and thickness of the plate 50.

[0097] First, select a material (such as aluminum alloy, titanium alloy, or stainless steel). Only one material is selected for testing in this experiment, but materials can be changed in subsequent steps for comparison.

[0098] The thickness of the plate 50 should start from the minimum plate thickness (such as 2 mm), and then gradually increase the thickness of the plate 50 (such as 5 mm, 10 mm). Ensure that the same material and thickness are used for testing in each experiment, and record the specific dimensions of each plate 50.

[0099] Step 2: Adjust the rotation speed of the stirring head 310.

[0100] Before starting to adjust the rotation speed of the stirring head 310, ensure that the material and thickness of the plate 50 are fixed, and the welding speed is also temporarily kept unchanged.

[0101] Set the rotation speed of the stirring head 310 to the minimum value (such as 300 r / min). Starting from the minimum speed, gradually increase the rotation speed of the stirring head 310 by 50 r / min or 100 r / min each time, and observe the change in the quality of the weld 510.

[0102] After that, each time the speed is increased, observe the appearance of the weld 510 (whether it is flat, whether there are defects such as pores and cracks), and at the same time use a microscope to analyze the microstructure of the weld 510. If the quality of the weld 510 deteriorates (such as cracks, pores, or other defects appear), stop increasing the speed, and record the rotation speed of the stirring head 310 at this time as the optimal rotation speed of the stirring head 310. At this time, the welding quality reaches the best state, and the speed should not be increased further.

[0103] Step 3: Adjust the welding speed.

[0104] After determining the optimal rotation speed of the stirring head 310 in Step 2, fix this speed value.

[0105] Then, set the welding speed to the minimum value (such as 50 mm / min), and gradually increase the welding speed, increasing by 25 mm / min or 50 mm / min in each test.

[0106] After each increase in the welding speed, observe the changes in the appearance and microstructure of the weld 510. If the quality of the weld 510 improves (the weld 510 becomes more flat and the defects decrease), continue to increase the welding speed; if the quality deteriorates (such as tearing or weld beads appear), stop increasing the welding speed, and record the welding speed at this time as the optimal welding speed.

[0107] Step 4: Repeat the test for different plate 50 thicknesses.

[0108] Keep the material unchanged and gradually increase the thickness of the plate 50 (for example, from 2 mm to 5 mm, and then to 10 mm).

[0109] Repeat steps 2 and 3. For the plate 50 of each thickness, repeat the above steps of adjusting the rotational speed of the stirring head 310 and the welding speed.

[0110] The optimal rotational speed of the stirring head 310 and the optimal welding speed at each thickness should be recorded separately.

[0111] Step 5: Test the welding parameters of different materials.

[0112] Finally, change the material of the plate 50 (for example, change from aluminum alloy to titanium alloy or stainless steel).

[0113] Then, repeat steps 2, 3, and 4. For each new material at different thicknesses, repeat adjusting the rotational speed of the stirring head 310 and the welding speed, and record the optimal welding parameters (optimal rotational speed of the stirring head 310 and optimal welding speed) of each material at different thicknesses.

[0114] Step 6: Data analysis and summary.

[0115] Organize the optimal rotational speed of the stirring head 310 and the optimal welding speed of each material and at each thickness into a table (not shown) of the weld 510 quality - corresponding to the optimal rotational speed of the stirring head 310 and the optimal welding speed, so as to facilitate the operator to quickly determine the appropriate optimal rotational speed of the stirring head 310 and the optimal welding speed according to the material and thickness of the plate 50, and realize the control of the welding quality.

[0116] Compared with the traditional combined experimental method, the above experimental method reduces the complex parameter combination tests, focusing on the two key variables of the rotational speed of the stirring head 310 and the welding speed. This not only saves time but also reduces the complexity of the experiment. Secondly, each experiment can be adjusted according to the actual situation to meet the requirements of different materials and thicknesses. Moreover, by observing the change of the weld 510 quality, the parameters can be adjusted in real time to ensure the reliability of the experimental results. Further, by gradually increasing the thickness of the plate 50 and changing the material, various actual application scenarios can be covered, with strong universality and operability. Moreover, each test strictly controls a single variable, avoiding the interference of multiple variables on the results, and the experimental data is more accurate and stable. Finally, the optimal rotational speed range of the stirring head 310 and the corresponding optimal welding speed range for each material at each plate thickness are obtained.

[0117] The step of "S200: Determine the target temperature reduction amplitude of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510 according to the environmental parameters, the target parameters of the plate 50, the target parameters of the stirring head 310, and the control parameters of the stirring head 310, and each heat dissipation area corresponds to each cooling channel 412" in the above proposed control method for controlling the friction stir welding device, as Figure 9 shown, includes the following two steps:

[0118] S210: Determine the welding temperature of the weld 510 of the plate member 50 and each heat dissipation area on both sides of the weld 510 according to the material of the plate member 50, the thickness of the plate member 50, the material of the stirring head 310, the rotation speed of the stirring head 310, and the moving rate of the stirring head 310 along the direction of the weld 510 of the plate member 50, and each heat dissipation area corresponds one-to-one with each cooling channel 412.

[0119] S220: Determine the target temperature reduction amplitude of the weld 510 of the plate member 50 and each heat dissipation area on both sides of the weld 510 according to the welding temperature of the weld 510 of the plate member 50 and each heat dissipation area on both sides of the weld 510 and the ambient temperature.

[0120] Among them, the step of "S210: Determine the welding temperature of the weld 510 of the plate member 50 and each heat dissipation area on both sides of the weld 510 according to the material of the plate member 50, the thickness of the plate member 50, the material of the stirring head 310, the rotation speed of the stirring head 310, and the moving rate of the stirring head 310 along the direction of the weld 510 of the plate member 50, and each heat dissipation area corresponds one-to-one with each cooling channel 412" includes the following three steps as Figure 10 shown:

[0121] S211: Determine the temperature of the weld 510 of the plate member 50 during welding according to the material of the plate member 50, the thickness of the plate member 50, the material of the stirring head 310, the rotation speed of the stirring head 310, and the moving rate of the stirring head 310 along the direction of the weld 510 of the plate member 50.

[0122] S212: Determine the influence range of the weld 510 temperature on both sides of the weld 510 of the plate member 50 according to the temperature of the weld 510 of the plate member 50 during welding and the material of the plate member 50.

[0123] S213: Divide the range affected by the weld 510 temperature of the plate member 50 and on both sides of the weld 510 into several heat dissipation areas, and determine the welding temperature of each heat dissipation area, and each heat dissipation area corresponds one-to-one with each cooling channel 412 when the cooling mechanism 40 is in the working state.

[0124] In the above three steps of S211, S212, and S213, the temperature of the weld 510 of the plate member 50 during welding, the influence range of the weld 510 temperature on both sides of the weld 510 of the plate member 50, and the welding temperature at each heat dissipation area can also be obtained by looking up tables or through experiments. The specific methods are as follows:

[0125] In step S100 (S110, S120, and S130), the optimal rotational speed of the stirring head 310 and the optimal welding speed for each material plate 50 at different thicknesses are determined through experiments. Because, in order to determine the temperature at the weld 510 of the plate 50, the temperature of the weld 510 and the influence range of the weld 510 temperature on both sides of the weld 510 can be measured simultaneously during the above-mentioned experiments to determine the optimal rotational speed of the stirring head 310 and the optimal welding speed for each material at different thicknesses, so as to provide a basis for heat dissipation area division and gradient cooling control. The specific data collection and experimental process are as follows:

[0126] The test objective is to determine the temperature at the weld 510, the influence range of the weld 510 temperature on both sides of the weld 510, and the welding temperature within the range affected by the weld 510 temperature on both sides of the weld 510 for the plate 50 of various materials at different thicknesses under the optimal rotational speed of the stirring head 310 and the optimal welding speed. Among them, the temperature at the edge of the influence range of the weld 510 temperature on both sides of the weld 510 should be the same as the ambient temperature.

[0127] When determining the experiments of the optimal rotational speed of the stirring head 310 and the optimal welding speed for the plate 50 of various materials at different thicknesses in step S100, a number of temperature sensors (thermocouples or infrared thermometers) can also be installed on both sides of the weld 510 of the plate 50 of various materials and different thicknesses. Specifically, the temperature sensors are arranged on the weld 510 and its two sides, and the distance from the center of the weld 510 gradually increases. And the real-time temperature changes during the welding process are recorded by high-frequency sampling.

[0128] Experimental steps:

[0129] During the above process of the plate 50 of various materials and different plate thicknesses under the optimal rotational speed of the stirring head 310 and the optimal welding speed, measure the temperature distribution of the weld 510 and its two sides, and record the temperature data when welding is completed.

[0130] Through repeated experiments, ensure the stability and accuracy of the data.

[0131] After analyzing the results, establish the corresponding relationship between the weld 510 temperature and the welding parameters (material, plate thickness, rotational speed, speed). And record the weld 510 temperature and its influence range on both sides of the area.

[0132] When querying the database, a hierarchical and queryable weld 510 quality database needs to be constructed, specifically as follows:

[0133] Material layer: Classify and store materials such as aluminum alloy, titanium alloy, and stainless steel.

[0134] Plate thickness layer: Subdivide different plate thicknesses for each material.

[0135] Parameter layer: Store the optimal rotational speed of the stirring head 310, the optimal welding speed, the temperature of the weld 510, and the temperature distribution range on both sides of the weld 510 for each plate thickness.

[0136] Heat dissipation area layer: Record the target temperature and the temperature reduction amplitude of the heat dissipation area according to the influence range of the temperature of the weld 510.

[0137] When querying the optimal parameters, input the material and thickness of the plate 50 to obtain the corresponding material of the stirring head 310, the optimal rotational speed range of the stirring head 310, and the optimal welding speed range.

[0138] To query the temperature distribution of the weld 510 and the areas on both sides, input the material of the plate 50, the thickness of the plate 50, the optimal rotational speed of the stirring head 310, and the optimal welding speed to determine the temperature distribution of the weld 510 and the areas on both sides thereof (the influence range of the temperature of the weld 510 on both sides of the weld 510 of the plate 50 and the approximate average welding temperature of each heat dissipation area).

[0139] In summary, with the support of the above database, the temperature of the weld 510, the influence range of the temperature of the weld 510 on both sides of the weld 510 of the plate 50, and the welding temperature at each heat dissipation area can be obtained, providing data support for the subsequent step S400.

[0140] In S213, the influence range of the temperature of the weld 510 on both sides of the weld 510 of the plate 50 is divided into several heat dissipation areas. These heat dissipation areas are arranged in a direction gradually away from the weld 510, and follow the rule that the closer to the weld 510, the higher the temperature, and vice versa, the lower the temperature. Moreover, these heat dissipation areas are usually equally divided. The width of each heat dissipation area (perpendicular to the extension direction of the weld 510) should be divided according to the temperature distribution on both sides of the weld 510. For example, if the temperature difference between the temperature of the weld 510 and the temperature at the edge of both sides of the weld 510 affected by the temperature of the weld 510 is 200 degrees, along the direction from the weld 510 to the edge of the side of the weld 510 affected by the temperature of the weld 510, it is divided according to the temperature reduction interval. The selection of each temperature reduction interval needs to ensure the smoothness of the temperature reduction curve on both sides of the weld 510. Specifically, during the welding process, the temperature of the weld 510 will gradually spread from the center of the weld 510 to both sides, and the temperature distribution shows a gradient decrease. Therefore, the range of the areas on both sides of the weld 510 affected by the temperature of the weld 510 is determined based on the diffusion characteristics of the temperature of the weld 510. The specific steps are as follows:

[0141] During the welding process, use temperature sensors (such as thermocouples or infrared thermometers) to monitor the temperature at the center of the weld 510 and on both sides thereof in real time. Record the temperature distribution of the weld 510 when welding is completed, and determine the attenuation trend of the temperature, that is, the change rate when the temperature spreads from the center of the weld 510 to the outside.

[0142] The temperature - affected regions on both sides of the weld 510 are usually delimited according to the temperature change. Generally speaking, after a certain distance from the center of the weld 510, the temperature decays to near the ambient temperature or a lower value, and it no longer affects the welding quality of the area around the weld 510.

[0143] The regions on both sides of the weld 510 affected by temperature are divided into multiple heat - dissipation regions to more precisely control the cooling process. The division principle is usually based on the change of temperature gradient and the cooling requirement. The specific steps are as follows:

[0144] According to the temperature decay curves on both sides of the weld 510, the temperature - affected regions are gradually divided into multiple heat - dissipation regions according to the temperature gradient. Each heat - dissipation region usually represents a specific temperature range. For example, the heat - dissipation regions can be divided according to different intervals of temperature decrease. The region closer to the weld 510 has a higher temperature, and the region farther from the weld 510 has a lower temperature.

[0145] To ensure a smooth temperature distribution, the division of the heat - dissipation regions is usually equidistant, that is, the width of each region is equal or divided at a predetermined interval. This division method helps to control the consistency of cooling, avoiding too fast or too slow cooling in local areas, so as to ensure that the temperatures of the weld 510 and the surrounding regions drop to the target temperature synchronously.

[0146] For example, assuming that the temperature range of the weld 510 from 800 °C to 50 °C has a span of 15 cm to 20 cm, this section of the region can be equally divided into multiple small regions, such as each 1 cm as a heat - dissipation region. This helps the cooling fluid to act more precisely on different temperature ranges, thus achieving gradient cooling.

[0147] Furthermore, in practical applications, the width of the heat - dissipation regions can be adjusted according to the temperature distribution on both sides of the weld 510. For example, in the region where the temperature change is relatively gentle, wider heat - dissipation regions may be selected, while in the region where the temperature change is relatively fast, narrower heat - dissipation regions are chosen. The purpose of this is to optimize the cooling efficiency and make the cooling effect of each region more uniform.

[0148] Moreover, the target cooling amplitude of each heat - dissipation region is set according to the difference between the temperature of the weld 510 and the ambient temperature. The target cooling amplitude should be determined according to the required cooling time and the set temperature difference. Each heat - dissipation region corresponds one - to - one with the cooling flow channel 412, ensuring that each region can receive effective cooling treatment. Each cooling flow channel 412 will adjust the injection volume of the coolant and the flow rate of the air flow according to the target cooling amplitude of the corresponding heat - dissipation region. This can ensure that during the welding process, the temperatures of the weld 510 and its two sides can be evenly and effectively reduced to the target temperature range.

[0149] In summary, the areas on both sides of the weld 510 affected by the temperature of the weld 510 are determined by measuring the temperature and attenuation trend of the weld 510, and then divided into multiple heat dissipation areas by equal spacing or temperature gradient method, ensuring that the temperature change in each area meets the requirements, and finally realizing the gradient cooling of the weld 510 and the areas on both sides thereof.

[0150] It should be noted that the width of the cooling channels 412 on the box body 410 in the cooling mechanism 40 should also be adapted to the width of the heat dissipation area to meet the cooling requirements of each heat dissipation area when the friction stir welding device is in the working state. When the friction stir welding device is in the working state, the abutting plane of the box body 410 is attached to the side of the plate 50 facing away from the welding table 10. The cooling channel 412 at the middle of each cooling channel 412 covers the weld 510 of the plate 50, and the other two groups of cooling channels 412 are symmetrically arranged on both sides of this cooling channel 412, and each cooling channel 412 in the two groups of cooling channels 412 covers each heat dissipation area in a one-to-one correspondence manner, cooperating with the independently controlled injector and fan to realize the independent cooling of the weld 510 and each cooling channel 412.

[0151] In step “S220: Determine the target cooling amplitude of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510 according to the welding temperature and ambient temperature of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510”, according to the query of the aforementioned database, the difference between the welding temperature and the ambient temperature of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510 can be known, and this difference is the target cooling amplitude at the weld 510 and each heat dissipation area.

[0152] It should be noted that reducing the temperature of the weld 510 and the areas on both sides to the ambient temperature only exists in the ideal state. Usually, after the weld 510 and the areas on both sides are cooled by the cooling mechanism 40, their temperatures will be slightly higher than the ambient temperature, but the influence of the temperature at this time on the quality of the weld 510 is extremely small and can be ignored. Therefore, the ambient temperature can be regarded as the target temperature.

[0153] Step “S300: Determine the continuous cooling duration at a single position of the weld 510 according to the control parameters of the stirring head 310 and the dimensional parameters of the box body 410” is as Figure 11 , including the following two steps:

[0154] S310: Obtain the corresponding length of the cooling channel 412 in the extending direction of the weld 510 of the plate 50 when the cooling mechanism 40 is in the working state.

[0155] S320: Determine the continuous cooling duration at a single position of the weld 510 according to the length of the box body 410 in the extending direction of the weld 510 of the plate 50 and the welding speed.

[0156] Among them, the corresponding length of the cooling channel 412 in S310 in the extension direction of the weld 510 of the plate 50 when the cooling mechanism 40 is in the working state can be approximately equal to the length of the box body 410 in the extension direction of the weld 510 when the stir friction welding device is in the working state. According to the optimal welding speed determined by looking up the table above, the length of time (continuous cooling time) that the box body 410 (cooling channel 412) at a single position on the weld 510 continuously covers the box body 410 (cooling channel 412) during the movement of the box body 410 along the weld 510 can be obtained.

[0157] It should be noted that at the starting point and the end point of the weld 510 of the plate 50, because the cooling mechanism 40 moves with the welding part 30, the box body 410 always lags behind the position where the stirring head 310 lags behind. The cooling mechanism 40 in the present application flows the coolant into the cooling channel 412 in conjunction with the air flow for heat dissipation. When the box body 410 is at the starting point and the end point of the weld 510, the part of the fitting plane 411 where the box body 410 and the plate 50 are fitted together will be suspended outside the plane of the plate 50. This results in the coolant in each cooling channel 412 being unable to be retained, which will affect the heat dissipation effect at the starting point and the end point of the weld 510, thereby affecting the quality of the weld 510. Therefore, in some embodiments, a detachable pad (not shown in the figure) can be further provided at the starting point and the end point of the weld 510 of the plate 50, the thickness of the pad being the same as the thickness of the plate 50 to be welded, the side of the pad facing the plate 50 is tightly fitted with the side of the plate 50, and a pad layer can be filled between the gap between the two to prevent the coolant from leaking from the gap, and the length of the pad should meet the length requirement of the box body 410 in the extension direction of the weld 510, so that when the box body 410 is at the starting point and the end point of the weld 510, the openings of each cooling channel 412 on the fitting plane 411 of the box body 410 can be sealed.

[0158] In the step of “S400: determining the target injection amount of the coolant in each cooling channel 412 and the target flow rate of the airflow according to the continuous cooling time and the target cooling range of the weld 510 of the plate 50 and the heat dissipation areas on both sides of the weld 510”, as shown in FIG. Figure 12 As shown, the following steps are included:

[0159] S410: Obtain the heat exchange area of ​​the positive projection contour of each cooling channel 412 on the side of the plate 50 away from the soldering station 10 when the cooling mechanism 40 is in the working state.

[0160] S420: Determine a target injection amount of the coolant and a target flow rate of the airflow in each cooling channel 412 according to the heat exchange area of ​​each cooling channel 412 and the continuous cooling time.

[0161] Among them, in step S410, the cooling efficiency of the heat dissipation area is related to the heat exchange area of ​​the cooling channel 412 corresponding to the heat dissipation area, and the heat exchange area of ​​the cooling channel 412 is the positive projection area of ​​the cooling channel 412 on the side of the plate 50 after the bonding plane 411 of the box body 410 is bonded to the side of the plate 50 away from the welding platform 10. In addition, except that the cooling channel 412 corresponding to the weld 510 of the plate 50 has a larger space, the other cooling channels 412 have the same shape and size, and are all smaller than the volume of the cooling channel 412 corresponding to the weld 510 of the plate 50. This is because in the process of the area on both sides of the weld 510 being synchronously reduced to the target temperature (ambient temperature) with the weld 510, the target cooling rate of the heat dissipation area on both sides of the weld 510 should be smaller than the target cooling rate of the weld 510 area, so that the cooling channel 412 with a larger space corresponding to the weld 510 can achieve faster cooling. In step S420, the target injection amount of the coolant and the target flow rate of the airflow in each cooling channel 412 are specifically determined, and the combined cooling effect of the coolant and the airflow must be considered. In the process of the coolant being injected into the cooling channel 412 and the airflow flowing rapidly in the cooling channel 412 to accelerate the evaporation of the coolant, the interaction between the coolant and the airflow plays a crucial role in the cooling efficiency.

[0162] Specifically, the following is a detailed and reproducible test method for determining the target injection amount range of the coolant and the target flow rate range of the airflow. This method can determine the target injection amount range of the coolant and the target flow rate range of the airflow through multiple experiments, so that under a given heat exchange area and continuous cooling time, the temperature of the cooling channel 412 can be reduced to ambient temperature (or below) within the target time.

[0163] The test device includes a temperature sensor, an injector (which can controllably inject a fixed amount of coolant), a fan (which can control the gas flow rate into the cooling channel 412) and a cooling channel 412 model (the shape and size are the same as the cooling channel 412 in the box body 410). Among them, the temperature sensor is used to monitor the temperature change of each cooling channel 412 in real time, with an accuracy of at least ±0.1°C, and the injector can adjust the injection amount (such as a flow meter or pump control system), and can accurately adjust the coolant flow within a predetermined range. The fan can adjust the airflow rate (such as a fan or air compressor) to ensure that the gas flow rate into the channel is within the target range. The cooling channel 412 model is a real or simulated cooling channel 412, which has the same heat exchange area as the real cooling channel 412 to ensure that the actual heat dissipation process can be simulated.

[0164] The preliminary preparations for the experiment include:

[0165] The cooling channel 412 in the experimental device is heated to a set initial temperature (for example, the temperature of the simulation plate 50 can be set to 200-500° C., depending on actual needs).

[0166] Ensure that the temperature of the experimental environment is stable, usually set at room temperature (e.g., 20 - 25 °C).

[0167] Set the continuous cooling time as the duration of continuous cooling, which is determined by the aforementioned step S320.

[0168] The determination of experimental variables includes:

[0169] According to the equipment specifications and actual situation, set multiple ranges of coolant flow rates (e.g., 0.5 L / min, 1.0 L / min, 1.5 L / min, 2.0 L / min, etc.).

[0170] Set multiple ranges of air flow velocities (e.g., 1 m / s, 2 m / s, 3 m / s, 4 m / s, etc.).

[0171] The implementation of the experiment includes:

[0172] Experimental group design. Based on the set ranges of coolant injection volume and air flow velocity, design multiple experimental groups to ensure wide coverage of combinations. For example, an experimental matrix including all combinations of both coolant injection volume and air flow velocity can be set. Specific examples: the coolant flow rate can be 0.5 L / min, 1.0 L / min, 1.5 L / min, 2.0 L / min. The air flow velocity can be 1 m / s, 2 m / s, 3 m / s, 4 m / s. Conduct multiple experiments for each combination to ensure the statistical reliability of the data.

[0173] Experimental steps include:

[0174] Initialize the experimental equipment to ensure that the coolant system and air flow regulation system are ready.

[0175] Start the experiment at the set initial temperature and record the start time.

[0176] Set the selected coolant injection volume and air flow velocity and continuously observe the temperature change.

[0177] Record the temperature change in the cooling channel 412 at regular intervals (e.g., every 10 seconds), especially the temperature after the duration of continuous cooling, until the target temperature range reaches the ambient temperature or below within the duration of continuous cooling. After completing the experiment, record the cooling process, required time, and final temperature for each experiment.

[0178] The recording and analysis of data include:

[0179] When recording data, ensure that data such as temperature, coolant flow rate, air flow velocity, and experimental time for each experimental combination are recorded in detail.

[0180] When processing the experimental data, draw a temperature change curve based on the experimental results to visualize the effects of different coolant injection amounts and air flow velocities on the temperature change.

[0181] Analyze the cooling rate in each group of experiments for the processed experimental data to find the coolant injection amount and air flow velocity corresponding to the best cooling effect.

[0182] It should be noted that during the experiment, it is necessary to ensure the uniform temperature in the cooling channel 412 to avoid local overheating or overcooling. The temperature uniformity can be checked by reasonably designing the channel structure or adding auxiliary temperature sensors. At the same time, the injection amount and flow rate should be adjusted step by step. Do not adjust the coolant injection amount or air flow velocity too quickly at one time. Adjust step by step and observe its influence on the temperature change to avoid excessive temperature changes. And the experiment needs to be repeated multiple times. Each experimental group should conduct at least three experiments to ensure the reliability and reproducibility of the experimental data.

[0183] Finally, based on the experimental results, it may be possible to obtain an empirical formula between the coolant injection amount and air flow velocity and the cooling rate or temperature change, but this requires the support of a large amount of data. However, it can be guaranteed that through the above experiments, the best combination of coolant injection amount and air flow velocity can be preliminarily determined under different parameter conditions, that is, the target injection amount range of the coolant and the target flow velocity range of the air flow, to ensure that the expected cooling effect can be achieved in actual operation.

[0184] The step of "S500 controls the operation of the friction stir welding device according to the control parameters of the stirring head 310, the size parameters of each cooling channel 412, the continuous cooling duration, the target injection amount of the coolant in each cooling channel 412, and the target flow velocity of the air flow" in the foregoing control method, as Figure 13 shown, includes:

[0185] S510: Determine the total injection height of the coolant in the cooling channel 412 according to the target injection amount of the coolant in the cooling channel 412 and the heat exchange area of the corresponding cooling channel 412.

[0186] S520: Determine the single injection amount, interval duration, and total injection times of the coolant in the cooling channel 412 according to the total injection height of the coolant in the cooling channel 412, the continuous cooling duration, and the target flow velocity of the air flow in the cooling channel 412.

[0187] S530: Control the operation of each injector corresponding to each cooling channel 412 according to the single injection amount, interval duration, and total injection times of the coolant, and control the operation of each fan corresponding to each cooling channel 412 according to the target flow velocity of the air flow and the interval duration.

[0188] Among them, in step S510, the parameter of the total injection height of the coolant in the cooling channel 412 can be obtained by determining the heat exchange area of the cooling channel 412 in the aforementioned step S410 and the target injection volume of the coolant in each cooling channel 412 in S420. And in step S520, the "single injection volume of the coolant in the cooling channel 412" should satisfy that after the coolant is injected into the cooling channel 412 and falls on the weld 510 or the heat dissipation areas on both sides of the weld 510, it can quickly evaporate under the action of the welding temperature and the airflow with the target flow rate. Moreover, the shorter the evaporation time, the better it can meet the cooling requirements, because the shorter the evaporation time means the more times it can be repeated during the continuous cooling duration, and the better the cooling effect. The interval duration can be obtained by comprehensively considering the evaporation time of the single coolant injection volume and how much heat needs to be absorbed for the heat dissipation area corresponding to the cooling channel 412 to drop from the initial temperature (welding temperature) to the target temperature (ambient temperature).

[0189] Furthermore, in order to ensure that the coolant can be evenly laid on the surface of the corresponding heat dissipation area of the plate 50 after being injected into the cooling channel 412, the friction stir welding device further includes a plurality of nozzles (not shown in the figure). The plurality of nozzles are arranged inside each cooling channel 412 in a one-to-one correspondence, and the plurality of nozzles are connected to the liquid inlet 413 of the plurality of cooling channels 412, as Figures 4 to 6 shown. The nozzle is configured to evenly lay the coolant injected into the cooling channel 412 on the surface of the plate 50 when the injector injects the coolant into the corresponding cooling channel 412. The nozzle can be embodied as an atomizing nozzle in a specific manner. And it should be noted that in order to make the coolant falling on the heat dissipation area of the plate 50 as even as possible, multiple nozzles can be arranged in one cooling channel 412. Similarly, in order to adapt to multiple nozzles, a flow dividing pipe (not shown in the figure) needs to be added between the nozzle and the liquid inlet 413. The flow dividing pipe includes a main pipe and a plurality of branch pipes. The main pipe is connected to the liquid inlet 413, and each branch pipe is connected to each nozzle in a one-to-one correspondence, so as to evenly spray the coolant with a single injection volume on the surface of the heat dissipation area of the plate 50.

[0190] In step S530, both the single injection volume and the interval duration of the coolant can be determined simultaneously when determining the target flow rate of the air flow in step S420. This is because under the action of the air flow at the target flow rate, the single injection volume of the coolant forms a uniform coolant layer in the cooling channel 412, and the layer thickness should satisfy rapid evaporation under the action of the air flow at the target flow rate. The evaporation duration is the interval duration. It should be noted that the interval duration should satisfy: the quotient obtained by dividing the continuous cooling duration by the sum of the single injection duration and the interval duration of the coolant, and then multiplying the product by the temperature drop of the cooling channel 412 after the complete evaporation of the single injection volume of the coolant (the total temperature drop of the heat dissipation area during the continuous cooling duration) should be greater than the difference between the welding temperature of the heat dissipation area (the welding temperature of the weld 510 transferred to the heat dissipation area during welding) and the target temperature (ambient temperature). After the interval duration meets this condition, the total number of injections can be obtained by simply dividing the continuous cooling duration by the sum of the interval duration and the injection duration of the coolant.

[0191] Specifically, by controlling the single injection volume of the coolant, the accumulation thickness of the coolant in the cooling channel 412 is controlled. Therefore, determining the single injection volume and the interval duration of the coolant in step 520 are both continuations of step S420. After determining the target injection volume of the coolant and the target flow rate of the air flow in step S420, it is possible to continue to measure the accumulation thickness of the coolant in the cooling channel 412 at which the best evaporation rate can be achieved in combination with the target flow rate of the air flow. Multiple repeated experiments are required to determine the evaporation rate of the coolant at each accumulation thickness (such as 5mm, 10mm, 15mm, etc.).

[0192] Furthermore, the target flow rate of the air flow can also be adjusted according to requirements to re-determine the optimal target flow rate range of the air flow. As long as the product of the number of single injections of the coolant and the single injection volume of the coolant within the overall continuous cooling duration is greater than or equal to the target injection volume, and the product of the sum of the single injection duration and the interval duration of the coolant and the number of single injections of the coolant is less than or equal to the continuous cooling time. The specific determination method is as follows:

[0193] First, for the determination of the single injection volume of the coolant, it can be experimentally determined how the coolant is evenly distributed on the surface of the heat dissipation area of the plate 50 after being injected into the cooling channel 412. This requires adjusting the injection volume according to the properties of the coolant (such as viscosity, thermal conductivity, etc.) and the target air flow rate. In step S420, the target injection volume of the coolant and the target flow rate of the air flow have been determined. Next, a series of experiments are carried out with different injection volumes (such as 5mm, 10mm, 15mm, etc.) as test variables to observe the distribution effect of the coolant in the cooling channel 412, especially its evaporation rate and cooling efficiency. Through experiments, the evaporation rate corresponding to each injection volume can be obtained, and the best injection volume can be found. This injection volume enables the coolant to evaporate rapidly under the action of the air flow, thereby achieving the best cooling effect.

[0194] Secondly, combined with the experimental results, determine the single injection duration and the interval duration of the coolant. The injection duration of the coolant needs to ensure that the coolant can be fully distributed and combined with the air flow for evaporation. At the same time, the interval duration after injection should be long enough to ensure that the evaporated coolant can be completely cooled within the temperature control of the welding area to reach the ideal temperature range.

[0195] The selection of the interval duration needs to consider the evaporation duration of the coolant, the heat dissipation effect of the cooling channel 412, and the required cooling rate. Generally, the interval duration can be repeatedly adjusted through experiments to determine whether it can make the temperature of the welding area drop to the required temperature within the specified continuous cooling duration.

[0196] Then, after determining the single injection volume and injection duration of the coolant, the total number of injections required can be calculated according to the total duration of continuous cooling. The number of injections should satisfy: single injection volume of coolant × number of injections ≥ target injection volume.

[0197] At the same time, it is also necessary to ensure that the total injection time does not exceed the continuous cooling time. The calculation method is to divide the continuous cooling duration by the sum of the single injection duration and the interval duration to obtain the total number of injections.

[0198] It should be noted that the product of the cooling value of the target heat dissipation area after a single injection of the coolant and the total number of injections should be greater than the difference between the welding temperature of the heat dissipation area and the target temperature (ambient temperature), so that the total number of injections meets the overall cooling requirements. And this calculation of the total number of injections can be carried out through repeated experiments and optimization to ensure that the final cooling effect meets the expectations.

[0199] Furthermore, during the experiment, according to the accumulation thickness and evaporation rate of the coolant, the target flow rate of the air flow can be appropriately adjusted to optimize the evaporation process of the coolant. By changing the air flow rate, the evaporation rate of the coolant can be adjusted, thereby affecting the heat dissipation efficiency. Through multiple experiments, the optimal air flow rate range can be found, and the single injection volume and interval duration of the coolant can be adjusted according to this range, so that the entire cooling process is more efficient.

[0200] In summary, this control method adopts a differential cooling strategy for different heat dissipation areas, precisely controls the temperature gradient of the weld 510 and the areas on both sides thereof, thereby avoiding excessive cooling of the areas on both sides of the weld 510, resulting in large tensile stresses or cracks between the weld 510 and the areas on both sides of the weld 510. Compared with the traditional water cooling method, this method can effectively adjust the coolant flow rate, air flow, and flow channel design, achieve a uniform decrease in temperature during the welding process, avoid the accumulation of thermal stress caused by uneven local cooling, significantly improve the welding quality, and optimize the mechanical properties of the joint.

[0201] The above content described in this specification is only an example of the present invention. Those skilled in the art to which the present invention pertains can make various modifications, supplements, or use similar means of substitution to the specific embodiments described, as long as they do not deviate from the content of this specification of the present invention or exceed the scope defined by this claims, they shall fall within the protection scope of the present invention.

Claims

1. A control method for a friction stir welding device for welding the seam of two plate members. The friction stir welding device includes a controlled welding part and a cooling mechanism that moves with the welding part. The cooling mechanism includes a box body, a number of controlled injectors, and a number of controlled fans. One side of the box body is provided with a fitting plane that fits against the side of the plate member when the cooling mechanism is in the working state, and a number of cooling channels are constructed at the fitting plane. The cooling channel in the middle is arranged opposite to the weld of the plate member, and the remaining cooling channels are evenly distributed on both sides of the weld of the plate member. A number of injectors and a number of fans are respectively and correspondingly connected to a number of cooling channels to inject coolant and introduce air flow into each cooling channel respectively; Characterized in that, The control method includes: Obtaining environmental parameters and target parameters of the plate member, and determining the target parameters of the stirring head and the control parameters of the stirring head according to the target parameters of the plate member; wherein, the environmental parameter is the environmental temperature, the target parameter of the plate member is the material and thickness of the plate member, the target parameter of the stirring head is the material of the stirring head, and the control parameters of the stirring head are the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate member; Determining the target cooling amplitude of the weld of the plate member and each heat dissipation area on both sides of the weld according to the environmental parameters, the target parameters of the plate member, the target parameters of the stirring head, and the control parameters of the stirring head, and each heat dissipation area corresponds to each cooling channel one by one; Determining the continuous cooling duration of a single position of the weld according to the control parameters of the stirring head and the box body size parameters; Determining the target injection amount of the coolant and the target air flow rate in each cooling channel according to the continuous cooling duration and the target cooling amplitude of the weld of the plate member and each heat dissipation area on both sides of the weld; Controlling the operation of the friction stir welding device according to the control parameters of the stirring head, the size parameters of each cooling channel, the continuous cooling duration, the target injection amount of the coolant in each cooling channel, and the target air flow rate.

2. The control method for a friction stir welding device according to claim 1, characterized in that: The welding part further includes a stirring head that rotates controllably; A number of liquid inlets, a number of air inlets, a number of air outlets, and a number of liquid inlets that are respectively and correspondingly connected to a number of cooling channels are provided on the surface of the box body. A number of liquid inlets are respectively connected to a number of injectors, and a number of air inlets are respectively connected to a number of fans; The friction stir welding device further includes: A thermometer for detecting the environmental temperature; A welding table including a material supporting plane for placing the plate member; A positioning fixture connected to the welding table, and the positioning fixture controllably fixes the plate member placed on the material supporting plane on the material supporting plane; A controller connected to each injector, each fan, the thermometer, and the welding part to control the operation of each injector, each fan, and the welding part.

3. The control method of a friction stir welding device according to claim 1, characterized in that Obtaining environmental parameters and target parameters of the plate member, and determining the target parameters of the stirring head and the control parameters of the stirring head, includes: Obtaining the environmental temperature, the material of the plate member, and the thickness of the plate member; Determining the material of the stirring head according to the material of the plate member; Determining the rotation speed of the stirring head and the moving rate of the stirring head along the weld direction of the plate member according to the material and thickness of the plate member.

4. The control method of a friction stir welding device according to claim 3, characterized in that, The target temperature reduction range of the plate weld and each heat dissipation area on both sides of the weld is determined according to the environmental parameters, the target parameters of the plate, the target parameters of the mixing head and the control parameters of the mixing head, and each heat dissipation area corresponds to each cooling flow channel one by one, including: The welding temperature of the plate weld and each heat dissipation area on both sides of the weld is determined according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving speed of the stirring head along the plate weld direction, and each heat dissipation area corresponds to each cooling flow channel one by one; The target temperature reduction range corresponding to the plate weld and the heat dissipation areas on both sides of the weld is determined according to the welding temperature and the ambient temperature of the plate weld and the heat dissipation areas on both sides of the weld.

5. The control method of a friction stir welding device according to claim 4, characterized in that, The welding temperature of the plate weld and each heat dissipation area on both sides of the weld is determined according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving speed of the stirring head along the plate weld direction, and each heat dissipation area corresponds to each cooling flow channel one by one, including: The weld temperature of the plate during welding is determined according to the material of the plate, the thickness of the plate, the material of the stirring head, the rotation speed of the stirring head and the moving speed of the stirring head along the weld direction of the plate; Determine the influence range of the weld temperature on both sides of the plate weld according to the weld temperature and the material of the plate; The plate weld and the range on both sides of the weld affected by the weld temperature are divided into several heat dissipation areas, and the welding temperature of each heat dissipation area is determined, and each heat dissipation area corresponds to each cooling flow channel one by one when the cooling mechanism is in working state.

6. The control method of a friction stir welding device according to claim 3 or 4 or 5, characterized in that, The continuous cooling time at a position of the weld is determined according to the control parameters of the stirring head and the size parameters of the box body, including: Obtaining the corresponding length of the cooling channel in the extension direction of the plate weld when the cooling mechanism is in the working state; The continuous cooling time of a single position of the weld is determined according to the length of the cooling channel in the extension direction of the plate weld and the moving speed of the stirring head along the direction of the plate weld.

7. The control method of a friction stir welding device according to claim 6, wherein, The target injection amount of coolant in each cooling channel and the target flow rate of air flow are determined according to the continuous cooling time and the target cooling range of the plate weld and each heat dissipation area on both sides of the weld, including: Obtain the heat exchange area of ​​the orthographic projection contour of each cooling channel on the side of the plate away from the soldering station when the cooling mechanism is in a working state; The target injection amount of the coolant and the target flow rate of the airflow in each cooling channel are determined according to the heat exchange area of ​​each cooling channel and the continuous cooling time.

8. The control method of a friction stir welding device according to claim 7, characterized in that, The operation of the friction stir welding device is controlled according to the control parameters of the stirring head, the size parameters of each cooling channel, the target injection amount of the coolant in each cooling channel and the target flow rate of the air flow, including: Determine the total injection height of the coolant in the cooling channel according to the target injection amount of the coolant in the cooling channel and the heat exchange area of ​​the corresponding cooling channel; Determine a single injection amount, interval duration, and total injection times of the coolant in the cooling flow channel according to the total injection height of the coolant in the cooling flow channel, the continuous cooling time, and the target flow rate of the airflow in the cooling flow channel; The operation of each injector is controlled according to the single injection amount, interval time and total injection times of the coolant, and the operation of each fan is controlled according to the target flow rate and interval time of the airflow.

9. The control method of a friction stir welding device according to claim 8, characterized in that, The friction stir welding device also includes: A number of spray nozzles are arranged inside each cooling channel in a one-to-one correspondence, and the number of spray nozzles is connected to the liquid inlets of the number of cooling channels. The spray nozzles are configured to evenly lay the coolant injected into the cooling channel on the surface of the plate when the injector injects the coolant into the corresponding cooling channel.

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