Control method of friction stir welding device

Abstract

The invention provides a control method of a friction stir welding device, which overcomes the problem that the cooling rate is difficult to adjust accurately in the traditional water cooling mode by accurately controlling the temperature distribution of each area in the welding process, and comprises a welding table, a positioning clamp, a welding part and a cooling mechanism, according to the cooling mechanism, gradient cooling is conducted on welding seams and areas on the two sides of the plate through a plurality of cooling flow channels in a box body connected with the welding part, a plurality of injectors and fans are connected with the cooling flow channels, and the injection amount of cooling liquid and the flow speed of airflow are accurately adjusted; the controller calculates the target cooling amplitude of the welding seam and the heat dissipation areas on the two sides according to the environment parameters, the plate target parameters and the stirring head control parameters, and controls the injection amount of cooling liquid and the airflow velocity in all the flow channels according to the target cooling amplitude, so that the situation that the temperature difference between the welding seam and the areas on the two sides is too large is avoided; welding defects such as microcracks and deformation caused by non-uniform thermal stress in the welding process are prevented, and the welding quality and the joint strength are remarkably improved.

Description

Technical Field

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

[0002] Welding technology is widely used in the processing and manufacturing of metal materials, especially in the automotive, aerospace, shipbuilding, electronic equipment and other industries, where welding technology plays a vital role. In these industries, welded parts usually need to withstand complex working environments such as high temperature and stress, so the quality of welded joints is crucial. With the continuous development of welding technology, friction stir welding (FSW), as a new solid-state welding technology, is increasingly used in the welding of light alloys and high-strength steels due to its advantages such as low deformation, low residual stress and no melting. In order to ensure the quality of welding, it is crucial to control the temperature distribution during the welding process.

[0003] In traditional welding technology, water cooling systems are often widely used as a means of temperature control. The coolant flows through the welding area through a preset cooling pipe, thereby removing heat from the welding area. The coolant in the water cooling system usually covers the surface of the welding area in a relatively uniform manner, and the temperature is lowered by immersing the entire 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 in the welding area, and the temperature of the weld area is much higher than that of the surrounding area, which results in a significant thermal gradient during the welding process. The cooling rate of the areas on both sides of the weld is usually faster, which easily leads to a large temperature difference between the weld and the areas on both sides. This temperature difference causes the areas on both sides of the weld to shrink during the cooling process, which easily generates a large tensile stress on the weld. Excessive temperature difference and uneven stress may lead to the formation of microcracks, deformation of the weld joint, and even affect the overall welding quality and 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 object of the present invention is to provide a control method for a friction stir welding device which realizes precise cooling control of a welding area and its surrounding areas by controlling the injection amount of coolant, the flow rate of air flow and the layout of cooling channels, thereby achieving gradient cooling of the weld and the surrounding areas. The control method ensures the balance of the cooling process by calculating the continuous cooling time, thereby effectively avoiding the problems of cold cracks and excessive thermal stress caused by excessive temperature difference.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problem is: a control method for a stir friction welding device, which is used to weld the joints of two plates, the 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 plurality of controlled injectors and a plurality of controlled fans, one side of the box body is set as a fitting plane that fits with the side of the plate when the cooling mechanism is in a working state, and a plurality of cooling channels are constructed at the fitting plane, the cooling channel in the middle is arranged opposite to the plate weld, and the remaining cooling channels are evenly distributed on both sides of the plate weld, and the plurality of injectors and the plurality of fans are connected to the plurality of cooling channels one by one, so as to inject coolant and introduce air flow into each cooling channel respectively.

[0007] Control methods include: The environmental parameters and the target parameters of the plate are obtained, and the target parameters of the stirring head and the control parameters of the stirring head are determined according to the target parameters of the plate.

[0008] 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 stirring head and the control parameters of the stirring head, and each heat dissipation area corresponds to each cooling flow channel one by one.

[0009] The continuous cooling time at a single position of the weld is determined according to the control parameters of the stirring head and the box size parameters.

[0010] The target injection amount of coolant in each cooling channel and the target flow rate of the airflow are determined according to the continuous cooling time and the target cooling amplitude of the plate weld and each heat dissipation area on both sides of the weld.

[0011] The operation of the stir friction welding device is controlled according to the control parameters of the stirring head, the size parameters of each cooling channel, the continuous cooling time, the target injection amount of the coolant in each cooling channel and the target flow rate of the airflow.

[0012] Preferably, the welding part further comprises a stirring head, and the stirring head rotates in a controlled manner.

[0013] The surface of the box body is provided with a plurality of liquid inlets, a plurality of air inlets, a plurality of air outlets and a plurality of liquid inlets which are connected one-to-one with a plurality of cooling channels; the plurality of liquid inlets are connected one-to-one with a plurality of injectors; and the plurality of air inlets are connected one-to-one with a plurality of fans.

[0014] The friction stir welding device also includes: Thermometer to detect ambient temperature.

[0015] The welding table includes a receiving surface for placing the panel.

[0016] The positioning fixture is connected to the welding platform, and the positioning fixture can controllably fix the plate placed on the material-bearing plane on the material-bearing plane.

[0017] The controller is connected with each injector, each fan, the temperature meter and the welding part to control the operation of each injector, each fan and the welding part.

[0018] Preferably, obtaining the environmental parameters and the target parameters of the plate, 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, includes: Get the ambient temperature, the material of the panel, and the thickness of the panel.

[0019] The material of the stirring head is determined according to the material of the plate.

[0020] The rotation speed of the stirring head and the moving speed of the stirring head along the weld direction of the plate are determined according to the material and thickness of the plate.

[0021] Preferably, the target temperature reduction amplitude 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 stirring head and the control parameters of the stirring 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 movement rate of the stirring head along the weld direction of the plate, and each heat dissipation area corresponds to each cooling flow channel one by one.

[0022] 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.

[0023] Preferably, 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 weld direction of the plate, 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.

[0024] Determine the influence range of the weld temperature on both sides of the plate weld based on the weld temperature and the material of the plate.

[0025] 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.

[0026] Preferably, 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: Obtain the corresponding length of the cooling channel in the extension direction of the plate weld when the cooling mechanism is in the working state.

[0027] 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.

[0028] Preferably, the target injection amount of the coolant in each cooling channel and the target flow rate of the airflow are determined according to the continuous cooling time and the target cooling amplitude of the plate weld and each heat dissipation area on both sides of the weld, including: The heat exchange area of ​​each cooling channel is obtained from the positive projection contour of the side of the plate facing away from the soldering station when the cooling mechanism is in the working state.

[0029] 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.

[0030] Preferably, 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 airflow, and this step includes: 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: The total injection height of the coolant in the cooling flow channel is determined according to the target injection amount of the coolant in the cooling flow channel and the heat exchange area of ​​the corresponding cooling flow channel.

[0031] The single injection amount, interval duration and total injection times of the coolant in the cooling channel are determined according to the total injection height of the coolant in the cooling channel, the continuous cooling time and the target flow rate of the airflow in the cooling channel.

[0032] 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.

[0033] Preferably, the friction stir welding device further comprises: A plurality of nozzles 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 so that when the injector injects coolant into the corresponding cooling channel, the coolant injected into the cooling channel is evenly spread on the surface of the plate.

[0034] The beneficial effects of the embodiments of the present invention are as follows: Due to the control method of the stir friction welding device, the injection amount of coolant and the flow rate of the airflow can be accurately adjusted according to the temperature distribution during welding and the thermal gradient on both sides of the weld, avoiding the problem of the traditional water cooling method being unable to accurately control the cooling rate, and thus effectively solving the problem of excessive temperature difference during welding, reducing the risk of defects such as microcracks and deformation in the welded joints, and improving the welding quality and joint strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic top view of a welding portion according to an embodiment of the present invention is shown in which a cooling mechanism is aligned with a welding seam when the welding portion is working.

[0036] Figure 2 A schematic front view of a welding portion according to an embodiment of the present invention is shown in which a cooling mechanism is aligned with a welding seam when the welding portion is working.

[0037] Figure 3 A schematic rear view of a welding portion according to an embodiment of the present invention is shown in which a cooling mechanism is aligned with a welding seam when the welding portion is working.

[0038] Figure 4 A schematic structural diagram of a cooling mechanism according to an embodiment of the present invention is shown.

[0039] Figure 5 A schematic main cross-sectional view of a temperature reduction mechanism according to an embodiment of the present invention is shown.

[0040] Figure 6 A schematic rear cross-sectional view of a temperature reduction mechanism according to an embodiment of the present invention is shown.

[0041] Figure 7 A schematic flow chart of a control method for a friction stir welding device according to an embodiment of the present invention is shown.

[0042] Figure 8 The present invention is shown Figure 7 , which is a schematic flow chart of a method for determining the rotation speed of the stirring head and the moving speed of the stirring head along the weld direction of the plate in step S100.

[0043] Fig. 9 The present invention is shown Figure 7 , which is a schematic flowchart of a method for determining a target temperature reduction range of a weld and heat dissipation areas on both sides of the weld in step S200.

[0044] Fig.10 The present invention is shown Fig. 9 , which is a schematic flow chart of a method for determining the soldering temperature at each heat dissipation area in step S210 .

[0045] Fig.11The present invention is shown Figure 7 A schematic flow chart of a method for determining the continuous cooling time in step S300 is shown in FIG.

[0046] Fig.12 The present invention is shown Figure 7 FIG. 4 is a schematic flow chart of a method for determining a target injection amount of coolant and a target flow rate of airflow in step S400 .

[0047] Fig.13 The present invention is shown Figure 7 A schematic flow chart of the injector and fan control method in step S500 is shown in FIG.

[0048] Fig.14 1 is a schematic structural diagram showing a friction stir welding device according to an embodiment of the present invention.

[0049] Among them: 10, welding table; 110, material receiving plane; 20, positioning fixture; 30, welding part; 310, stirring head; 40, cooling mechanism; 410, box body; 411, fitting plane; 412, cooling flow channel; 413, liquid inlet; 414, air inlet; 415, air outlet; 50, plate; 510, weld. DETAILED DESCRIPTION

[0050] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0051] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 therefore cannot be understood as limiting the scope of protection 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 technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description created by the present application, unless otherwise specified, "multiple" means two or more.

[0052] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0053] like Figures 1 to 6 and Fig.14 As shown, a preferred embodiment of the present application provides a stir friction welding device for welding the joints of two plates 50, and the stir friction welding device includes a welding table 10, a positioning fixture 20, a welding part 30 and a cooling mechanism 40, wherein the welding table 10 includes a material receiving plane 110, the positioning fixture 20 is connected to the welding table 10 to fix the plate 50 on the material receiving plane 110 during the welding process, the welding part 30 moves in a controlled manner, and the welding part 30 includes a controlled rotating stirring head 310.

[0054] Among them, after the welding table 10 is installed, the material receiving plane 110 is parallel to the horizontal plane to prevent the plate 50 placed on the material receiving plane 110 from slipping. The positioning fixture 20 generally includes a clamping member and a driver, etc. The clamping member is constructed to be compatible with the plate 50. The clamping member is installed on the welding table 10 in a movable manner, and the clamping member can be rotated and / or moved relative to the welding table 10 so that the abutting surface of the clamping member can abut against the plate 50, and the plate 50 on the material receiving plane 110 is limited and fixed with the cooperation of multiple clamping components or other limiting members fixed on the material receiving plane 110. The driver can select a pneumatic cylinder or an electric push cylinder, etc. The welding mechanism is composed of a displacement mechanism and a welding part 30. The displacement mechanism can select a displacement module composed of a number of electric slides and guide rails, or a robotic arm, etc., and the specific method should be determined according to the use requirements. The welding part 30 is arranged at the moving end of the displacement mechanism to achieve flexible position change. The welding part 30 at least includes a motor, a coupling, a rotating shaft and a clamp for clamping the stirring head 310. The rotating shaft is connected to the output shaft of the motor through a coupling. The clamp is installed on the rotating shaft to rotate synchronously with the rotating shaft, and the clamp is usually detachable to facilitate the replacement of the stirring head 310.

[0055] In order to improve the quality of the weld 510 and ensure that the weld 510 area and the surrounding area can be synchronously reduced to the target temperature to avoid stress concentration and microcracks caused by excessive temperature difference, the stir friction welding device also includes a cooling mechanism 40, and the cooling mechanism 40 is connected to the welding part 30 to move with the welding part 30. The cooling mechanism 40 includes a box body 410, and 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 fixed on the material receiving plane 110 by the positioning mechanism away from the welding table 10, so as to cooperate with the coolant and airflow described later to cool the plate 50. The bonding surface of the box body 410 is provided with a plurality of cooling channels 412. The surface of the box body 410 is also provided with a plurality of liquid inlets 413, a plurality of air inlets 414 and a plurality of air outlets 415. Each liquid inlet 413 is connected to each cooling channel 412 in a one-to-one correspondence. The same is true for each air inlet 414 and each air outlet 415, which are connected to each cooling channel 412 in a one-to-one correspondence. Moreover, when the cooling mechanism 40 is in a working state, one of the cooling channels 412 is aligned with the weld 510 when the bonding plane 411 is bonded to the side of the plate 50 away from the welding platform 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.

[0056] Specifically, the box body 410 is embodied as a shell body approximately in a rectangular parallelepiped in a specific manner, one side of the box body 410 is a plane, which is the abutting plane, and the cooling channel 412 opened on the side is recessed toward the inside of the box body 410 to form a plurality of flat rectangular parallelepiped spaces inside the box body 410, and the cooling channel 412 will leave an opening at the abutting plane. The cooling channels 412 are arranged in parallel with 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 a working state, each cooling channel 412 is perpendicular to the side of the plate 50 away from the welding platform 10, wherein the channel aligned with the weld 510 is defined as the first channel, and the remaining cooling channels 412 are defined as the second channel, and the interval between the cooling channels 412 should be as narrow as possible to avoid the area corresponding to the fitting plane 411 and the interval being too large to affect heat dissipation and cooling. In addition, 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 outlet 415 in each cooling channel 412 is opened on the side of the box body 410 in the forward direction when the cooling mechanism 40 is in the working state, and the air inlet 414 is opened on the side of the box body 410 away from the forward direction. The liquid inlet 413 can be opened on the side of the box body 410 away from the plate 50, that is, the top of the box body 410.

[0057] In order to control the injection amount of the coolant and the flow rate of the airflow, the cooling mechanism 40 also includes a number of injectors (not shown in the figure), a number 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 achieve the flow of air 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. In addition, the controller is also connected to the displacement module or the robot arm to control the moving speed (welding speed) of the welding part 30 and the rotation speed of the stirring head 310.

[0058] However, although the above-mentioned friction stir welding device can cool down the weld 510 and the two sides of the weld 510 respectively, how to ensure that the weld 510 and the two sides of the weld 510 can be sufficiently cooled down at the welding speed so that the weld 510 and the two sides of the weld 510 can reach the target temperature after the box body 410 moves through the weld 510, it is necessary to further propose a control method suitable for the above-mentioned friction stir welding device, such as Figure 7 As shown, in order to meet the gradient cooling requirements of the weld 510 and the areas on both sides, the specific control method is as follows: S100 : Acquire environmental parameters and target parameters of the plate 50 , and determine target parameters of the stirring head 310 and control parameters of the stirring head 310 according to the target parameters of the plate 50 .

[0059] S200: 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 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 one by one.

[0060] S300: Determine the duration of continuous cooling 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 .

[0061] S400: Determine 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 amplitude of the weld 510 of the plate 50 and the heat dissipation areas on both sides of the weld 510.

[0062] S500: Controlling 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 time, the target injection amount of the coolant in each cooling channel 412 and the target flow rate of the airflow.

[0063] Among them, the step of “S100: obtaining environmental parameters and target parameters of the plate 50, and determining target parameters of the stirring head 310 and control parameters of the stirring head 310 according to the target parameters of the plate 50” is as follows: Figure 8 As shown, including: S110 : Acquire the ambient temperature, the material of the plate 50 , and the thickness of the plate 50 .

[0064] S120 : Determine the material of the stirring head 310 according to the material of the plate 50 .

[0065] S130: Determine the rotation speed of the stirring head 310 and the moving speed of the stirring head 310 along the direction of the weld 510 of the plate 50 according to the material and thickness of the plate 50 .

[0066] The environmental parameter is the ambient temperature, which can be obtained by a thermometer or a temperature sensor.

[0067] The target parameters of the plate 50 are the material of the plate 50 and the thickness of the plate 50 , which can be obtained from the supplier or through testing. No further details will be given here. The material and thickness of the plate 50 are related to the welding temperature of the weld 510 during welding, and the material of the plate 50 is also related to the selection of the material of the stirring head 310 .

[0068] Specific: Determine the material category of the plate 50 and clarify the basic metal type (such as aluminum, copper, titanium) and alloy characteristics of the plate 50.

[0069] Analyze the thermal conductivity of the plate 50, and determine the heat transfer efficiency during the welding process based on the thermal conductivity of the metal. For high thermal conductivity materials (such as aluminum alloys), it is necessary to select a stirring head 310 material with good heat resistance to prevent rapid heat dissipation from causing insufficient temperature of the weld 510. For low thermal conductivity materials (such as titanium alloys), the stirring head 310 material needs to have higher hardness and wear resistance. In addition, 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 high-temperature welding.

[0070] After determining the material of the stirring head 310 according to the above conditions, it is necessary to verify it in combination with experiments. You can refer to data from actual applications, such as the performance of the stirring head 310 when welding different materials, or confirm through experiments the stability and applicability of the selected stirring head 310 material in the actual welding process.

[0071] 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.

[0072] 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 the good quality of the weld 510, the optimal rotation speed range of the stirring head 310 and the optimal movement rate range of the stirring head 310 along the direction of the weld 510 of the plate 50 (optimal welding speed range) can be determined by looking up a table or conducting experiments.

[0073] Specific: According to the clear thickness of the plate 50 (such as plate thickness less than 5mm, plate thickness between 5mm and 10mm, and plate thickness greater than 10mm).

[0074] To evaluate the heat input requirement, 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 effect of the rotation speed of the stirring head 310 and the welding moving speed). Specifically, the heat input required for various common plate materials when welding and splicing in various common specifications and plate thicknesses can be determined by controlling a single variable repeatability test (the range of the rotation speed of the stirring head 310 and the range of the welding speed). The following are the specific test design and specific implementation steps: The purpose of this experiment is to find the optimal welding parameters (rotation speed of the stirring head 310 and welding speed) of the plates 50 of different materials and thicknesses by adjusting the rotation speed of the stirring head 310 and the welding speed to ensure maximum welding quality.

[0075] The welding material may be selected from various common metal plate 50 materials, such as aluminum alloy (such as 6061), titanium alloy (such as Ti-6Al-4V) and stainless steel (such as 304 stainless steel).

[0076] The thickness of the plate 50 starts from the minimum thickness and gradually increases, for example, 2 mm, 5 mm, and 10 mm.

[0077] The friction stir welding equipment includes a stirring head 310 , a welding table 10 , a motor, a welding positioning fixture 20 , and the like.

[0078] The measuring tools include a thermometer (to ensure that the ambient temperature is stable), a microscope (for microstructural inspection), and a mechanical testing device (for testing the strength of the weld 510).

[0079] The test steps include: Step 1: Determine the material and thickness of the plate 50.

[0080] First, select a material (such as aluminum alloy, titanium alloy, or stainless steel). In this experiment, only one material is selected for testing, but you can change the material for comparison in subsequent steps.

[0081] The thickness of the plate 50 should start from the minimum plate thickness (such as 2mm), and then gradually increase the thickness of the plate 50 (such as 5mm, 10mm). Make sure that the same material and thickness are used for each experiment, and record the specific dimensions of each plate 50.

[0082] Step 2: Adjust the rotation speed of the stirring head 310.

[0083] 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 temporarily kept unchanged.

[0084] Set the speed of the stirring head 310 to a minimum value (eg, 300 r / min). Starting from the minimum speed, gradually increase the speed of the stirring head 310 by 50 r / min or 100 r / min each time, and observe changes in the quality of the weld 510.

[0085] After that, after each increase in the rotation speed, observe the appearance of the weld 510 (whether it is flat, whether there are defects such as pores and cracks), and 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), stop increasing the rotation speed, and record the stirring head 310 rotation speed at this time as the optimal stirring head 310 rotation speed. At this time, the welding quality reaches the best state, and the rotation speed should not be increased further.

[0086] Step 3: Adjust the welding speed.

[0087] After the optimum rotation speed of the stirring head 310 is determined in step 2, the rotation speed value is fixed.

[0088] Then, set the welding speed to the minimum value (such as 50mm / min) and gradually increase the welding speed by 25mm / min or 50mm / min each time.

[0089] After each increase in welding speed, observe the appearance and microstructural changes of weld 510. If the quality of weld 510 improves (weld 510 becomes smoother and has fewer defects), continue to increase welding speed; if the quality deteriorates (such as cracks and weld nodules), stop increasing welding speed and record the welding speed at this time as the optimal welding speed.

[0090] Step 4: Repeat the test with different panel 50 thicknesses.

[0091] The material remains unchanged and the thickness of the plate 50 is gradually increased (for example, from 2 mm to 5 mm, and then to 10 mm).

[0092] Repeat steps 2 and 3, and for each thickness of the plate 50, repeat the above steps of adjusting the rotation speed of the stirring head 310 and the welding speed.

[0093] The optimum stir head 310 speed and optimum welding speed for each thickness shall be recorded separately.

[0094] Step 5: Test welding parameters for different materials.

[0095] Finally, the material of the plate 50 is changed (eg, from aluminum alloy to titanium alloy or stainless steel).

[0096] Then, repeat steps 2, 3, and 4, repeatedly adjust the rotation speed of the stirring head 310 and the welding speed for each new material at different thicknesses, and record the optimal welding parameters (optimal rotation speed of the stirring head 310 and optimal welding speed) for each material at different thicknesses.

[0097] Step 6: Data analysis and summary.

[0098] The optimal stirring head 310 rotation speed and the optimal welding speed for each material and each thickness are organized into a table (not shown) corresponding to the weld 510 quality-optimal stirring head 310 rotation speed and the optimal welding speed, so that the operator can quickly determine the appropriate optimal stirring head 310 rotation speed and the optimal welding speed according to the material and thickness of the plate 50, thereby realizing the control of welding quality.

[0099] Compared with the traditional combination experimental method, the above-mentioned test method reduces the complex parameter combination test and focuses on the two key variables of the rotation 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 needs of different materials and thicknesses. Moreover, by observing the changes in the quality of the weld 510, the parameters can be adjusted in real time to ensure that the experimental results are reliable. Furthermore, by gradually increasing the thickness of the plate 50 and replacing the material, a variety of practical application scenarios can be covered, with strong universality and operability. Moreover, each test strictly controls a single variable to avoid multiple variables interfering with the results, and the experimental data is more accurate and stable. Finally, the optimal rotation speed range of the stirring head 310 for each material at each plate thickness and the corresponding optimal welding speed range were obtained.

[0100] In the control method for controlling the friction stir welding device proposed above, the step "S200: determining 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 one by one", such as Fig. 9 As shown, it includes the following two steps: S210: Determine the welding temperature of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510 according to the material of the plate 50, the thickness of the plate 50, the material of the stirring head 310, the rotation speed of the stirring head 310 and the moving speed of the stirring head 310 along the direction of the weld 510 of the plate 50, and each heat dissipation area corresponds one by one to each cooling channel 412.

[0101] S220: Determine the target temperature reduction range of the weld 510 of the plate 50 and the heat dissipation areas on both sides of the weld 510 according to the welding temperature of the weld 510 of the plate 50 and the heat dissipation areas on both sides of the weld 510 and the ambient temperature.

[0102] Among them, the step of “S210: determining the welding temperature of the weld 510 of the plate 50 and each heat dissipation area on both sides of the weld 510 according to the material of the plate 50, the thickness of the plate 50, the material of the stirring head 310, the rotation speed of the stirring head 310 and the moving speed of the stirring head 310 along the weld 510 of the plate 50, and each heat dissipation area corresponds to each cooling channel 412 one by one”, such as Fig.10 As shown, it includes the following three steps: S211: Determine the temperature of the weld 510 of the plate 50 during welding according to the material of the plate 50, the thickness of the plate 50, the material of the stirring head 310, the rotation speed of the stirring head 310 and the moving speed of the stirring head 310 along the direction of the weld 510 of the plate 50.

[0103] S212 : Determine the influence range of the temperature of the weld 510 on both sides of the weld 510 of the plate 50 according to the temperature of the weld 510 during welding of the plate 50 and the material of the plate 50 .

[0104] S213: Divide the weld 510 of the plate 50 and the range on both sides of the weld 510 affected by the temperature of the weld 510 into a plurality of heat dissipation areas, and determine the welding temperature of each heat dissipation area, and each heat dissipation area corresponds one-to-one to each cooling channel 412 when the cooling mechanism 40 is in working state.

[0105] In the above three steps S211, S212 and S213, the temperature of the weld 510 of the plate 50 during welding, the influence range of the weld 510 temperature on both sides of the weld 510 of the plate 50, and the welding temperature at each heat dissipation area can also be obtained by looking up a table or testing, and the specific method is as follows: In step S100 (S110, S120 and S130), the optimal stirring head 310 rotation speed and the optimal welding speed of 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 weld 510 temperature and the influence range of the weld 510 temperature on both sides of the weld 510 can be simultaneously determined during the aforementioned test process of determining the optimal stirring head 310 rotation speed and the optimal welding speed of each material at different thicknesses, thereby providing a basis for heat dissipation area division and gradient cooling control. The specific data collection and experimental process is as follows: The test objectives are 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 on both sides of the weld 510 within the range affected by the weld 510 temperature for plates 50 of various materials with different thicknesses at the optimal stirring head 310 rotation speed 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.

[0106] When determining the test of the optimal stirring head 310 rotation speed and the optimal welding speed for the plates 50 of various materials and different thicknesses in step S100, a plurality of temperature sensors (thermocouples or infrared thermometers) may be installed on both sides of the weld 510 of the plates 50 of various materials and different thicknesses. Specifically, the temperature sensors are arranged on the weld 510 and on both sides thereof, and the distance from the center of the weld 510 gradually increases. The real-time temperature changes during the welding process are recorded by high-frequency sampling.

[0107] Experimental steps: In the above-mentioned process, the plate 50 is subjected to various materials and different plate thickness conditions, and the temperature distribution of the weld 510 and its two sides is measured at the optimal stirring head 310 rotation speed and the optimal welding speed for top removal, and the temperature data when welding is completed is recorded.

[0108] By repeating the experiments, the stability and accuracy of the data were ensured.

[0109] After analyzing the results, the corresponding relationship between the temperature of the weld 510 and the welding parameters (material, plate thickness, rotation speed, speed) is constructed, and the temperature of the weld 510 and its influence range on the two side areas are recorded.

[0110] When designing the query database, a hierarchical and queryable weld 510 quality database needs to be constructed, as follows: Material layer: Classified storage of aluminum alloy, titanium alloy, stainless steel and other materials.

[0111] Plate thickness layer: Each material is subdivided into different plate thicknesses.

[0112] Parameter layer: for each plate thickness, the optimal stirring head 310 rotation speed, the optimal welding speed, the weld 510 temperature, and the temperature distribution range on both sides of the weld 510 are stored.

[0113] Heat dissipation area layer: according to the influence range of the temperature of the weld 510, the target temperature and the temperature reduction range of the heat dissipation area are recorded.

[0114] When searching for the best parameters, the material and thickness of the plate 50 are input, and the corresponding material of the stirring head 310, the best stirring head 310 rotation speed range and the best welding speed range are found.

[0115] To query the temperature of the weld 510 and the temperature distribution of the areas on both sides, input the material of the plate 50, the thickness of the plate 50, the optimal rotation speed of the stirring head 310 and the optimal welding speed to determine the temperature of the weld 510 and the temperature distribution of the areas on both sides (the influence range of the weld 510 temperature on both sides of the weld 510 of the plate 50 and the approximate average welding temperature of each heat dissipation area).

[0116] 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.

[0117] In S213, the temperature influence range of the weld 510 on both sides of the weld 510 of the plate 50 is divided into a plurality of heat dissipation areas, and 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. In addition, these heat dissipation areas are usually divided at equal intervals, and 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, the temperature difference between the weld 510 temperature and the edge of the weld 510 on both sides affected by the temperature of the weld 510 is 200 degrees, and the direction from the weld 510 to the edge of the side of the weld 510 affected by the temperature of the weld 510 is divided according to the temperature reduction interval, and 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, the temperature of the weld 510 will gradually diffuse from the center of the weld 510 to both sides during the welding process, and the temperature distribution will decrease in a gradient. Therefore, the range of the area 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: The temperature of the center and both sides of the weld 510 is monitored in real time by using a temperature sensor (such as a thermocouple or an infrared thermometer) during the welding process. The distribution of the temperature of the weld 510 when the welding is completed is recorded, and the temperature decay trend, that is, the rate of change of the temperature when it diffuses from the center of the weld 510 to the outside, is determined.

[0118] The temperature affected areas on both sides of the weld 510 are usually defined according to the temperature change. Generally speaking, after a certain distance from the center of the weld 510, the temperature decays to a value close to the ambient temperature or a lower value, and no longer affects the welding quality of the area around the weld 510.

[0119] The temperature-affected areas on both sides of the weld 510 are divided into multiple heat dissipation areas in order to more accurately control the cooling process. The division principle is usually based on the change of temperature gradient and cooling requirements, and the specific steps are as follows: According to the temperature attenuation curves on both sides of the weld 510, the temperature-affected area is gradually divided into multiple heat dissipation areas according to the temperature gradient. Each heat dissipation area usually represents a specific temperature segment. For example, the heat dissipation area can be divided according to different intervals of temperature reduction, and the temperature of the area closer to the weld 510 is higher, and the temperature of the area farther from the weld 510 is lower.

[0120] In order to ensure smooth temperature distribution, the heat dissipation areas are usually divided at equal intervals, that is, the width of each area is equal or divided at predetermined intervals. This division method helps to control the consistency of cooling and avoid the local area cooling too fast or too slow, thereby ensuring that the temperature of the weld 510 and the surrounding area is synchronously reduced to the target temperature.

[0121] For example, assuming that the area where the temperature of the weld 510 drops from 800°C to 50°C spans 15 cm to 20 cm, this area can be equally divided into multiple small areas, such as a heat dissipation area of ​​1 cm each. This helps the cooling fluid to act more accurately on different temperature sections, thereby achieving gradient cooling.

[0122] Furthermore, in practical applications, the width of the heat dissipation area can be adjusted according to the temperature distribution on both sides of the weld 510. For example, in an area where the temperature changes more slowly, a wider heat dissipation area may be selected, while in an area where the temperature changes more rapidly, a narrower heat dissipation area may be selected. The purpose of this is to optimize the cooling efficiency and make the cooling effect of each area more uniform.

[0123] In addition, the target temperature reduction range of each heat dissipation area is set according to the difference between the temperature of the weld 510 and the ambient temperature. The target temperature reduction range should be determined according to the required cooling time and the set temperature difference. Each heat dissipation area corresponds to the cooling channel 412 one by one to ensure that each area can be effectively cooled. Each cooling channel 412 will adjust the injection amount of the coolant and the flow rate of the airflow according to the target temperature reduction range of the corresponding heat dissipation area. This ensures that during the welding process, the temperature of the weld 510 and both sides thereof can be evenly and effectively reduced to the target temperature range.

[0124] 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, and ensuring that the temperature change of each area meets the requirements, and finally achieving gradient cooling of the weld 510 and the areas on both sides of it.

[0125] It should be noted that the width of the cooling channel 412 on the box body 410 in the cooling mechanism 40 must also be adapted to the width of the heat dissipation area to meet the cooling requirements of each heat dissipation area when the stir friction welding device is in working condition. When the stir friction welding device is in working condition, the abutting plane of the box body 410 is in contact with the side of the plate 50 facing away from the welding table 10, and the cooling channel 412 located in the middle of each cooling channel 412 is covered at the weld 510 of the plate 50, and the remaining two groups of cooling channels 412 are symmetrically arranged on both sides of the cooling channel 412, and each cooling channel 412 in the two groups of cooling channels 412 is covered on each heat dissipation area in a one-to-one corresponding manner, and cooperates with independently controlled injectors and fans to achieve independent cooling of the weld 510 and each cooling channel 412.

[0126] In step "S220: determine the target temperature reduction amplitude of the weld 510 of the panel 50 and the heat dissipation areas on both sides of the weld 510 according to the welding temperature of the weld 510 of the panel 50 and the heat dissipation areas on both sides of the weld 510 and the ambient temperature", according to the aforementioned database query, it can be known that the difference between the welding temperature of the weld 510 of the panel 50 and the heat dissipation areas on both sides of the weld 510 and the ambient temperature, and the difference is the target temperature reduction amplitude at the weld 510 and each heat dissipation area.

[0127] It should be noted that lowering the temperature of the weld 510 and the areas on both sides to the ambient temperature only exists in an ideal state. Usually, after the weld 510 and the areas on both sides are cooled by the cooling mechanism 40, their temperature will be slightly higher than the ambient temperature. However, the temperature at this time has little effect on the quality of the weld 510 and can be ignored. Therefore, the ambient temperature can be regarded as the target temperature.

[0128] Step "S300: Determine the continuous cooling time at a single position of the weld 510 according to the control parameters of the stirring head 310 and the size parameters of the box body 410" Fig.11 , including the following two steps: S310: Obtaining the corresponding length of the cooling channel 412 in the extending direction of the welding seam 510 of the plate 50 when the cooling mechanism 40 is in the working state.

[0129] S320: Determine the continuous cooling time 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.

[0130] 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.

[0131] 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.

[0132] 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. Fig.12 As shown, the following steps are included: 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] The preliminary preparations for the experiment include: 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).

[0138] Ensure that the experimental environment temperature is stable, usually set to room temperature (such as 20-25°C).

[0139] The continuous cooling time is set to the continuous cooling duration, which is determined by the aforementioned step S320.

[0140] The determination of experimental variables includes: According to equipment specifications and actual conditions, set multiple ranges of coolant flow rate (for example, 0.5L / min, 1.0L / min, 1.5L / min, 2.0L / min, etc.).

[0141] Set multiple ranges of air flow velocity (e.g., 1m / s, 2m / s, 3m / s, 4m / s, etc.).

[0142] The implementation of the experiment included: Experimental group design, based on the set coolant injection amount and air flow rate range, designs multiple experimental groups to ensure a wide range of combinations. For example, you can set an experimental matrix that contains all combinations of coolant injection amount and air flow rate. For example, the coolant flow rate can be: 0.5L / min, 1.0L / min, 1.5L / min, 2.0L / min. The air flow rate can be: 1m / s, 2m / s, 3m / s, 4m / s. Conduct multiple experiments for each combination to ensure the statistical reliability of the data.

[0143] Experimental steps include: Initialize the experimental equipment and ensure that the coolant system and air flow regulation system are ready.

[0144] Start the experiment at the set initial temperature and record the start time.

[0145] Set the selected coolant injection amount and air flow rate and continuously observe the temperature changes.

[0146] The temperature change in the cooling channel 412 is recorded at regular intervals (e.g., every 10 seconds), especially the temperature after the continuous cooling time, until the target temperature range reaches the ambient temperature or below within the continuous cooling time. After the experiment is completed, the cooling process, required time, and final temperature of each experiment are recorded.

[0147] Data recording and analysis include: When recording data, it is necessary to ensure that the temperature, coolant flow, air flow rate, experimental time and other data of each experimental combination are recorded in detail.

[0148] When processing the experimental data, a temperature change curve is drawn according to the experimental results to visualize the effects of different coolant injection amounts and air flow rates on temperature changes.

[0149] The processed experimental data are analyzed including the cooling rate in each group of experiments to find out the coolant injection amount and air flow rate corresponding to the best cooling effect.

[0150] It should be noted that during the experiment, it is necessary to ensure that the temperature in the cooling channel 412 is uniform to avoid local overheating or overcooling. The temperature uniformity can be checked by reasonably designing the channel structure or adding an auxiliary temperature sensor. At the same time, the injection amount and flow rate should be gradually adjusted. Do not adjust the coolant injection amount or air flow rate too quickly at one time. Adjust them gradually and observe the impact on temperature changes to avoid excessive temperature changes. In addition, the experiment needs to be repeated many times, and each experimental group should conduct at least three experiments to ensure the reliability and reproducibility of the experimental data.

[0151] Finally, based on the experimental results, it may be possible to derive an empirical formula between the amount of coolant injected and the airflow velocity and the cooling rate or temperature change, but this requires the support of a large amount of data. However, it is guaranteed that after the above experiments, the best combination of coolant injection amount and airflow velocity under different parameter conditions can be preliminarily determined, that is, the target injection amount range of the coolant and the target velocity range of the airflow, to ensure that the expected cooling effect can be achieved in actual operation.

[0152] In the aforementioned control method, the step “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 time, the target injection amount of the coolant in each cooling channel 412 and the target flow rate of the air flow” is as follows: Fig.13 As shown, including: S510 : determining a total injection height of the coolant in the cooling channel 412 according to a target injection amount of the coolant in the cooling channel 412 and a heat exchange area corresponding to the cooling channel 412 .

[0153] S520: Determine a 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 time, and the target flow rate of the airflow in the cooling channel 412.

[0154] S530: Control the operation of each injector corresponding to each cooling channel 412 according to the single injection amount of the coolant, the interval time and the total number of injections, and control the operation of each fan corresponding to each cooling channel 412 according to the target flow rate and interval time of the airflow.

[0155] Among them, the parameter of the total injection height of the coolant in the cooling channel 412 in step S510 can be obtained by determining the heat exchange area of ​​the cooling channel 412 in the aforementioned step S410 and determining the target injection amount of the coolant in each cooling channel 412 in step S420. In step S520, the "single injection amount 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 welding seam 510 or the heat dissipation area on both sides of the welding seam 510, it evaporates quickly under the action of the airflow of the welding temperature and the target flow rate, and the shorter the evaporation time, the more it can meet the cooling demand, because the shorter the evaporation time means that the more times it can be repeated within the continuous cooling time, the better the cooling effect. The interval time can be obtained by comprehensively considering the evaporation time of the single coolant injection amount and the amount of heat that needs to be absorbed by the heat dissipation area corresponding to the cooling channel 412 from the initial temperature (welding temperature) to the target temperature (ambient temperature).

[0156] Further, in order to ensure that the coolant can be evenly spread 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), which are arranged in a one-to-one correspondence inside each cooling channel 412, and the plurality of nozzles are connected to the liquid inlets 413 of the cooling channel 412, such as Figures 4 to 6 As shown, the nozzle is configured to make the coolant injected into the cooling channel 412 evenly spread 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 uniform as possible, a plurality of nozzles can be arranged in a cooling channel 412. Similarly, in order to adapt to the plurality of nozzles, a shunt pipe (not shown in the figure) needs to be added between the nozzle and the liquid inlet 413. The shunt 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 that the coolant injected in a single time is evenly sprayed on the surface of the heat dissipation area of ​​the plate 50.

[0157] The single injection amount and interval duration of the coolant in step S530 can be determined at the same time as the target flow rate of the airflow is determined in step S420. This is because under the action of the airflow at the target flow rate, the single injection amount of the coolant forms a uniform coolant layer in the cooling channel 412, and the layer thickness should be sufficient to evaporate quickly under the action of the airflow at the target flow rate. The evaporation time is the interval duration. It should be noted that the interval duration should meet the following conditions: the quotient obtained by dividing the continuous cooling time by the sum of the single injection time of the coolant and the interval duration, and then multiplying the product obtained by the temperature reduction of the cooling channel 412 after the single injection amount of coolant is completely evaporated (the total temperature reduced in the heat dissipation area during the continuous cooling time) should be greater than the difference between the welding temperature of the heat dissipation area (the welding temperature of the weld 510 temperature transferred to the heat dissipation area during welding) and the target temperature (ambient temperature). When the interval duration meets this condition, the total number of injections can be obtained by simply dividing the continuous cooling time by the sum of the interval duration and the injection time of the coolant.

[0158] Specifically, the accumulation thickness of the coolant in the cooling channel 412 is controlled by controlling the single injection amount of the coolant. Therefore, the single injection amount and interval duration of the coolant determined in step 520 are both continuations of step S420. After the target injection amount of the coolant and the target flow rate of the airflow are determined in step S420, the accumulation thickness of the coolant in the cooling channel 412 can be further determined to achieve the best evaporation rate in combination with the target flow rate of the airflow. The test needs to be repeated many times to determine the coolant evaporation rate at each accumulation thickness (for example, 5 mm, 10 mm, 15 mm, etc.).

[0159] Furthermore, the target flow rate of the airflow can also be adjusted according to demand to re-determine the optimal target flow rate range of the airflow, as long as the product of the number of single injections of coolant and the single injection amount of coolant within the overall continuous cooling time is greater than or equal to the target injection amount, and the product of the sum of the single injection time of coolant and the interval time and the number of single injections of coolant is less than or equal to the continuous cooling time. The specific determination method is as follows: First, the single injection amount of the coolant can be determined by experimentally determining 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 amount according to the properties of the coolant (such as viscosity, thermal conductivity, etc.) and the target airflow rate. In step S420, the target injection amount of the coolant and the target flow rate of the airflow have been determined. Next, a series of experiments are carried out with different injection amounts (such as 5mm, 10mm, 15mm, etc.) as experimental 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 amount can be obtained, and the optimal injection amount can be found. This injection amount allows the coolant to evaporate quickly under the action of the airflow, thereby achieving the best cooling effect.

[0160] Secondly, combined with the experimental results, the single injection time and interval time of the coolant are determined. The injection time of the coolant needs to ensure that the coolant can be fully distributed and evaporated in combination with the airflow. At the same time, the interval time after injection should be long enough to ensure that the evaporated coolant can be completely cooled within the temperature control of the welding area and reach the ideal temperature range.

[0161] The selection of the interval time needs to consider the cooling liquid evaporation time, the heat dissipation effect of the cooling channel 412 and the required cooling rate. Generally, the interval time can be repeatedly adjusted through experiments to determine whether it can reduce the temperature of the welding area to the required temperature within the specified continuous cooling time.

[0162] Then, after determining the single injection volume and injection duration of the coolant, the total number of injections required can be calculated based on the total duration of continuous cooling. The number of injections should satisfy: single injection volume of coolant × number of injections ≥ target injection volume.

[0163] 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 time by the sum of the single injection time and the interval time to obtain the total number of injections.

[0164] It should be noted that the product of the temperature drop value of the target heat dissipation area after a single injection of 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 can meet the overall cooling requirements. The calculation of the total number of injections can be performed through repeated experiments and optimization to ensure that the final cooling effect meets expectations.

[0165] Furthermore, during the experiment, the target flow rate of the airflow can be adjusted appropriately according to the accumulation thickness and evaporation rate of the coolant to optimize the evaporation process of the coolant. By changing the airflow rate, the evaporation rate of the coolant can be adjusted, thereby affecting the heat dissipation efficiency. Through multiple experiments, the optimal airflow velocity range can be found, and the single injection amount and interval length of the coolant can be adjusted according to this range, making the entire cooling process more efficient.

[0166] In summary, the control method adopts differentiated cooling strategies for different heat dissipation areas to accurately control 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, which would result in large tensile stress or cracks between the weld 510 and the two sides of the weld 510. Compared with the traditional water cooling method, this method can effectively adjust the coolant flow rate, airflow and flow channel design, achieve uniform temperature drop during welding, avoid thermal stress accumulation caused by uneven local cooling, significantly improve welding quality, and optimize the mechanical properties of the joint.

[0167] The above contents described in this specification are merely examples of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, as long as they do not deviate from the contents of the present specification or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A control method for a friction stir welding device, used for welding the seams of two plates, the friction stir welding device comprising a controlled welding part and a cooling mechanism moving with the welding part, the cooling mechanism comprising a box body, a plurality of controlled injectors and a plurality of controlled fans, one side of the box body is set as a fitting plane that fits with the side of the plate when the cooling mechanism is in a working state, and a plurality of cooling channels are constructed at the fitting plane, the cooling channel in the middle is arranged opposite to the plate weld, and the remaining cooling channels are evenly distributed on both sides of the plate weld, and the plurality of injectors and the plurality of fans are connected to the plurality of cooling channels one by one, so as to inject cooling liquid and introduce air flow into each cooling channel respectively; It is characterized in that Control methods include: Acquire environmental parameters and target parameters of the plate, and determine target parameters of the mixing head and control parameters of the mixing head according to the target parameters of the plate; 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 stirring head and the control parameters of the stirring head, and each heat dissipation area corresponds to each cooling flow channel one by one; Determine the continuous cooling time of a single position of the weld according to the control parameters of the stirring head and the size parameters of the box body; Determine the target injection amount of the coolant in each cooling channel and the target flow rate of the airflow 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; The operation of the stir friction welding device is controlled according to the control parameters of the stirring head, the size parameters of each cooling channel, the continuous cooling time, the target injection amount of the coolant in each cooling channel and the target flow rate of the airflow.

2. The control method of a friction stir welding device according to claim 1, characterized in that: The welding part also includes a stirring head, which rotates in a controlled manner; The surface of the box body is provided with a plurality of liquid inlets, a plurality of air inlets, a plurality of air outlets and a plurality of liquid inlets which are connected one-to-one with a plurality of cooling channels, the plurality of liquid inlets are connected one-to-one with a plurality of injectors, and the plurality of air inlets are connected one-to-one with a plurality of fans; The friction stir welding device also includes: Thermometer to detect ambient temperature; A welding table, including a receiving surface for placing the plate; A positioning fixture is connected to the welding table, and the positioning fixture controls the plate placed on the material-bearing plane to be fixed on the material-bearing plane; The controller is connected with each injector, each fan, the temperature meter 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: Obtain environmental parameters and target parameters of the panel, and determine target parameters of the mixing head and control parameters of the mixing head according to the target parameters of the panel, including: Get the ambient temperature, the material of the panel and the thickness of the panel; Determine the material of the mixing head according to the material of the plate; The rotation speed of the stirring head and the moving speed of the stirring head along the weld direction of the plate are determined according to the material and thickness of the plate.

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. A control method for a friction stir welding device according to claim 3, 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, characterized in that: 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 plurality of nozzles 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 so that when the injector injects coolant into the corresponding cooling channel, the coolant injected into the cooling channel is evenly spread on the surface of the plate.

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