Automatic pressure control device, system and method for friction stir welding

Abstract

The invention discloses a friction stir welding automatic pressure control device, system and method, and particularly relates to the technical field of friction stir welding, the friction stir welding automatic pressure control device comprises a cylinder body, an oil cavity is formed in the inner side of the cylinder body, an adjusting sleeve is slidably connected to the inner side of the cylinder body, and a piston piece slidably connected in the oil cavity is fixedly connected to the outer side of the adjusting sleeve. Through a hydraulic actuating mechanism composed of the cylinder body, the oil cavity, the piston piece and the adjusting sleeve, rapid adjustment of the axial pressure of the stirring head is achieved, the transmission shaft is installed in the adjusting sleeve through the radial bearing, it is ensured that power transmission for driving the stirring head to rotate and axial pressurizing motion driven by the adjusting sleeve are completely decoupled and do not interfere with each other, and meanwhile the stirring head can be driven to rotate. The supporting piece is matched with the plane bearing, axial counter-acting force in the welding process is reliably borne, it is guaranteed that when pressure is dynamically adjusted, the rotating stability of the stirring head is not affected, and a stable, reliable and rapid-response pressure applying platform is provided for the welding process.

Description

Technical Field

[0001] This invention relates to the field of friction stir welding technology, and more specifically, to an automatic pressure control device, system, and method for friction stir welding. Background Technology

[0002] Friction stir welding, as an advanced solid-state welding technology, has been widely used in high-end manufacturing fields such as aerospace, rail transportation, and new energy vehicles due to its core advantages of no melting during the welding process, high joint quality, environmental friendliness, and compatibility with various metal materials such as aluminum alloys, titanium alloys, and high-strength steel. Its weld quality and joint mechanical properties are highly dependent on the precise control of welding pressure; the stability of pressure parameters directly affects weld formation, grain refinement, and joint strength consistency.

[0003] However, in the friction stir welding process, existing pressure control technologies mainly rely on preset pressure curves or single parameters, which cannot adapt to changes in weld temperature, differences in plasticity between dissimilar materials, and pressure requirements of thin / thick plates in real time. This leads to problems such as incomplete penetration, weld collapse, and uneven strength during welding. Especially during the initial welding, steady state, and special working conditions, the lack of linkage control between torque and temperature dynamic changes makes it difficult to achieve rapid and accurate pressure adjustment, affecting welding quality and efficiency.

[0004] This invention provides an automatic pressure control device, system, and method for friction stir welding, aiming to solve the problems of existing friction stir welding pressure control technology relying on preset curves or single parameters, which cannot be linked to real-time changes in torque and temperature, resulting in unstable welding quality, low efficiency, and difficulty in adapting to complex working conditions such as welding dissimilar materials and high-speed welding. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic pressure control device, system and method for friction stir welding, in order to solve the problems mentioned in the background art. The existing friction stir welding pressure control technology relies on preset curves or single parameters, and cannot be linked to adjust according to real-time changes in torque and temperature, resulting in unstable welding quality, low efficiency and difficulty in adapting to complex working conditions such as dissimilar materials and high-speed welding.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an automatic pressure control device for friction stir welding, comprising: The cylinder block has a sealed oil chamber inside; The pressure regulating mechanism includes an adjusting sleeve slidably connected to the cylinder body and a piston fixedly connected to the outside of the adjusting sleeve and sealingly sliding in the oil chamber. The pressure regulating mechanism is used to adjust the pressure applied to the workpiece by the stirring head mounted thereon by hydraulically driving the adjusting sleeve to move along its axial direction. A rotary transmission mechanism includes a transmission shaft rotatably connected inside the adjusting sleeve via a radial bearing, the transmission shaft being used to transmit the rotational power of an external drive device to the stirring head; An axial force bearing mechanism includes a support member disposed on the outer periphery of the stirring head and a plane bearing installed between the support member and the adjusting sleeve. The axial force bearing mechanism is used to withstand the axial reaction force generated by welding and maintain the rotational stability of the stirring head during the axial movement of the adjusting sleeve and the rotation of the stirring head.

[0007] Preferably, the oil chamber is provided with an oil inlet and an oil outlet, and hydraulic oil flows into or out of the oil chamber through the oil inlet and the oil outlet to drive the piston and the adjusting sleeve to move axially in both directions.

[0008] An automatic pressure control system for friction stir welding includes the aforementioned automatic pressure control device for friction stir welding, and: The acquisition unit includes a torque sensor, a pressure sensor, and a temperature sensor, used to acquire torque signals, actual pressure signals, and temperature signals in real time during the welding process; The control unit is used to receive and analyze torque signals, temperature signals and actual pressure signals, identify working conditions based on the linkage logic of torque and temperature and generate pressure regulation commands. The execution unit includes an external oil supply device for receiving pressure regulation commands and driving the regulating sleeve to move to change the pressure of the stirring head by adjusting the flow direction and flow rate of hydraulic oil in the oil chamber. The acquisition unit, control unit, and execution unit form a closed-loop control link to achieve real-time adaptive adjustment of welding pressure.

[0009] Preferably, the torque sensor is disposed inside the adjusting sleeve and is used to connect the drive shaft and the external drive device to collect torque signals that reflect the degree of plasticity of the material; The pressure sensor is disposed between the adjusting sleeve and the plane bearing, and is used to detect the actual pressure signal applied to the workpiece by the stirring head; The temperature sensor is mounted on the outside of the cylinder with its detection end facing the stirring head via a bracket, and is used to collect temperature signals that reflect the welding heat input status in a non-contact manner. Both the oil inlet and the oil outlet are connected to the external oil supply device to achieve bidirectional flow control of hydraulic oil within the oil chamber.

[0010] An automatic pressure control method for friction stir welding, applied to the aforementioned automatic pressure control system for friction stir welding, includes the following steps: Real-time signal acquisition: The acquisition unit acquires torque signals, temperature signals, and actual pressure signals during the welding process in real time. Linkage analysis and decision-making: The torque signal and temperature signal are transmitted to the control unit, which performs linkage analysis on the two according to preset logic rules and generates a preliminary pressure adjustment command; Pressure closed-loop execution: The execution unit executes the initial pressure regulation command, and drives the regulating sleeve to move by adjusting the hydraulic oil in the oil chamber to change the pressure of the stirring head; Pressure verification and compensation: The control unit determines whether the latest actual pressure signal fed back by the pressure sensor falls within the target pressure preset range that matches the current welding conditions. If the pressure does not fall within the target range, a compensation adjustment command is generated and sent to the execution unit for pressure fine-tuning until the actual pressure signal stabilizes within the target pressure preset range.

[0011] Preferably, in the linkage analysis and decision-making steps, the preset logical rules include: If the torque signal is higher than the set reference range and the temperature signal is lower than the set reference range, a command to increase the pressure is generated. If the torque signal is below the set reference range and the temperature signal is above the set reference range, a command to reduce the pressure is generated. If both the torque and temperature signals are within the steady-state reference range, a command to maintain or fine-tune the pressure is generated.

[0012] Preferably, in the linkage analysis and decision-making step, the control unit identifies the current welding stage or working condition based on the temporal variation characteristics of the torque signal and temperature signal, and executes a differentiated pressure regulation strategy based on the identification result. The identification and regulation strategies include: When the torque signal is detected to rise rapidly from its initial value to its peak value and the temperature signal is detected to rise from room temperature but not to a steady state, it is determined to be the welding start-up stage, and a rapid pressurization command is generated. When the torque and temperature signals are both detected to be stable within the set range, it is determined to be in the steady-state welding stage, and a command is generated to maintain the pressure or to slowly adjust it based on minor fluctuations. When a sudden and drastic change in the torque signal is detected while the temperature signal does not change significantly in sync, it is determined that a special working condition of encountering a hard point is encountered, and a rapid decompression command is generated.

[0013] Preferably, in the pressure closed-loop execution step, by controlling the hydraulic oil to enter and exit the oil chamber through the oil inlet and outlet, the piston and adjusting sleeve are driven to move axially, thereby changing the pressure of the stirring head on the workpiece, and the actual pressure signal is returned to the control unit through the continuous feedback of the pressure sensor.

[0014] Preferably, the pressure calibration and compensation steps specifically include: After each pressure closed-loop execution step is completed, the control unit immediately reads the latest actual pressure signal collected by the pressure sensor; Compare the latest actual pressure signal with the target pressure range preset for the current welding stage or working condition; If the latest actual pressure signal does not fall within the target pressure range, a compensation adjustment command is generated based on the magnitude and direction of the deviation, and the process returns to the pressure closed-loop execution step to perform fine-tuning. Repeat the above comparison and compensation process until the actual pressure signal stabilizes within the target pressure range.

[0015] Preferably, in the pressure verification and compensation step, an internal loop of execution, verification and compensation is formed, constituting a complete closed-loop control to ensure that the actual pressure value is accurately tracked and stabilized within the target pressure preset range.

[0016] The technical effects and advantages of this invention are as follows: 1. This invention utilizes a hydraulic actuator consisting of a cylinder, oil chamber, piston, and adjusting sleeve to achieve rapid adjustment of the axial pressure of the stirring head. The transmission shaft is mounted inside the adjusting sleeve via a radial bearing, ensuring complete decoupling between the power transmission driving the rotation of the stirring head and the axial pressurization motion driven by the adjusting sleeve, preventing interference between them. Simultaneously, the cooperation between the support component and the plane bearing reliably withstands the axial reaction force during the welding process, ensuring that the rotational stability of the stirring head remains unaffected during dynamic pressure adjustment, thus providing a stable, reliable, and responsive pressure application platform for the welding process. 2. This invention forms a closed-loop control link through a data acquisition unit, a control unit, and an execution unit. The system uses a torque sensor to sense the torque signal reflecting the degree of material plasticity in real time, a temperature sensor to sense the temperature signal reflecting the heat input state in real time, and a pressure sensor to provide actual pressure feedback. After the control unit performs linkage analysis and working condition identification on the torque and temperature signals, it dynamically generates instructions to drive the execution unit to adjust the flow direction and flow rate of hydraulic oil in the oil chamber, thereby accurately controlling the pressure of the stirring head. This system effectively overcomes the limitations of relying on preset curves or single parameters, and realizes adaptive pressure adjustment for special working conditions such as welding of dissimilar materials, transition of the welding steady-state stage, and hard points, significantly improving the stability of the welding process and the consistency of joint quality. 3. This invention uses a control unit to make a comprehensive judgment based on the coupling relationship between torque and temperature signals, and identifies special working conditions such as the welding initiation stage, steady-state stage, or hard spots. Different pressure adjustment strategies are triggered for different working conditions, and the actual pressure is ensured to be tracked and maintained within the target value range in real time through the pressure verification and compensation process. This method deeply integrates the dynamic changes of the dual parameters of torque and temperature into the control logic, and strengthens the verification and correction of the final execution effect. It achieves precise matching between welding pressure and real-time material status, effectively preventing defects such as incomplete penetration, weld collapse, and abnormal wear of the stirring head, and greatly enhances process adaptability and reliability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the automatic pressure control device of the present invention.

[0018] Figure 2 This is a cross-sectional view of the internal structure of the automatic pressure control device of the present invention.

[0019] Figure 3 This is a schematic diagram of the automatic pressure control system of the present invention.

[0020] Figure 4 This is a flowchart of the automatic pressure control method of the present invention.

[0021] Figure 5 This is a flowchart illustrating the linkage analysis and decision-making logic of the automatic pressure control method of the present invention.

[0022] Figure 6 This is a flowchart of the pressure closed-loop and compensation process of the automatic pressure control method of the present invention.

[0023] The attached figures are labeled as follows: 1. Cylinder block; 12. Oil chamber; 13. Piston; 14. Oil inlet; 15. Oil outlet; 2. Adjusting sleeve; 3. Stirring head; 21. Radial bearing; 22. Drive shaft; 23. Support; 24. Planar bearing; 25. Bracket; 4. Torque sensor; 5. Pressure sensor; 6. Temperature sensor. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0025] refer to Figure 1 and Figure 2An automatic pressure control device for friction stir welding according to an embodiment of the present invention includes a cylinder body 1, an oil chamber 12 is provided on the inner side of the cylinder body 1, an adjusting sleeve 2 is slidably connected to the inner side of the cylinder body 1, a piston 13 is fixedly connected to the outer side of the adjusting sleeve 2 and slidably connected in the oil chamber 12, and an oil inlet 14 and an oil outlet 15 are respectively provided at both ends of the oil chamber 12.

[0026] refer to Figure 2 The inside of the adjusting sleeve 2 is rotatably connected to the drive shaft 22 via the radial bearing 21. One end of the drive shaft 22 extends out of the adjusting sleeve 2 and is fixedly connected to the stirring head 3. The other end of the drive shaft 22 is connected to an external drive device, which can be a motor. The drive shaft 22 can be a telescopic rod structure, used to cooperate with the axial movement of the adjusting sleeve 2.

[0027] refer to Figure 2 A support member 23 is fixedly connected to the outer periphery of the stirring head 3. A plane bearing 24 is installed on the side of the support member 23 near the adjusting sleeve 2. The plane bearing 24 is sleeved on the outer periphery of the stirring head 3.

[0028] In actual use, when welding begins, the external drive device drives the transmission shaft 22 to rotate, which in turn drives the stirring head 3 to rub against the workpiece.

[0029] When pressure needs to be increased, oil is supplied to the inlet 14 and oil is drawn from the outlet 15. The hydraulic oil enters the oil chamber 12 and pushes the piston 13 and the adjusting sleeve 2 fixed thereto to move towards the workpiece. During the process of the adjusting sleeve 2 moving towards the workpiece, it drives the stirring head 3 to press down, thereby increasing the pressure.

[0030] When pressure needs to be reduced, oil is introduced from the oil outlet 15 and drawn from the oil inlet 14. The hydraulic oil enters the oil chamber 12 and pushes the piston 13 and the adjusting sleeve 2 fixed thereto to move away from the workpiece. During the process of the adjusting sleeve 2 moving away from the workpiece, it drives the stirring head 3 to move upward, thereby reducing the pressure.

[0031] The adjusting sleeve 2 is connected to the transmission shaft 22 via the radial bearing 21. The flat bearing 24 bears the axial force without affecting the rotation of the stirring head 3, ensuring that the rotation and axial movement of the stirring head 3 do not interfere with each other during the pressure adjustment process, thus ensuring the stability of the welding process.

[0032] In summary, the hydraulic actuator, consisting of cylinder 1, oil chamber 12, piston 13, and adjusting sleeve 2, enables rapid adjustment of the axial pressure of the stirring head 3. The transmission shaft 22 is mounted inside the adjusting sleeve 2 via radial bearing 21, ensuring complete decoupling between the power transmission driving the rotation of the stirring head 3 and the axial pressurization motion driven by the adjusting sleeve 2, preventing interference between them. Simultaneously, the cooperation between the support member 23 and the plane bearing 24 reliably withstands the axial reaction force during the welding process, ensuring that the rotational stability of the stirring head 3 remains unaffected during dynamic pressure adjustment, thus providing a stable, reliable, and responsive pressure application platform for the welding process. Example

[0033] refer to Figures 1 to 3 An automatic pressure control system for friction stir welding includes a data acquisition unit, a control unit, and an execution unit, which form a closed-loop control link to achieve real-time adaptive adjustment of welding pressure.

[0034] The acquisition unit includes a torque sensor 4, a pressure sensor 5, and a temperature sensor 6, which are used to acquire torque signals, temperature signals, and actual pressure signals in real time during the welding process, providing data support for the control unit.

[0035] refer to Figure 1 and Figure 2 The torque sensor 4 is installed inside the adjusting sleeve 2. One end of the torque sensor 4 is connected to the drive shaft 22, and the other end is connected to the external drive device. The torque sensor 4 can be a dynamic torque sensor. The torque sensor 4 is used to collect the torque change signal of the drive shaft 22 in real time. This signal directly reflects the degree of plasticity of the material in the welding area. Pressure sensor 5 is set between adjusting sleeve 2 and plane bearing 24. Pressure sensor 5 can be a strain gauge pressure sensor. Pressure sensor 5 is used to detect the actual pressure signal applied to the workpiece by stirring head 3, and provides feedback basis for pressure closed-loop regulation. Temperature sensor 6 is fixedly connected to the outside of oil cavity 12 via bracket 25. The detection end of temperature sensor 6 faces stirring head 3. Temperature sensor 6 can be an infrared temperature sensor. Temperature sensor 6 is used to collect the weld temperature signal in the contact area between stirring head 3 and workpiece in a non-contact manner. This signal directly reflects the heat input state of the welding process.

[0036] The control unit receives and analyzes the signals transmitted by the acquisition unit, performs analysis and judgment based on the linkage logic of torque and temperature, and generates pressure adjustment commands. After the execution unit completes each pressure adjustment action, the control unit immediately reads the latest feedback value of the pressure sensor 5 and compares it with the target pressure preset range calculated based on the current identified working conditions. If the actual pressure does not fall into the range, the control unit will generate corresponding compensation adjustment commands according to the magnitude and direction of the deviation and send them to the execution unit for precise correction until the actual pressure stabilizes within the preset range.

[0037] The execution unit includes an external oil supply device, which is used to receive and execute pressure regulation commands issued by the control unit, and realize axial pressure regulation of the stirring head 3 through hydraulic drive; Both the oil inlet 14 and the oil outlet 15 are connected to an external oil supply device to achieve bidirectional flow control of hydraulic oil in the oil chamber 12. The external oil supply device can be an oil pump.

[0038] In actual operation, the torque signal, temperature signal and actual pressure signal collected by the acquisition unit are synchronously transmitted to the control unit.

[0039] The control unit automatically identifies the current welding stage and whether there are any special working conditions based on torque and temperature signals and in combination with preset judgment logic. Specifically, the change trend of torque signal is used to judge the fluctuation of material plasticity, and the change trend of temperature signal is used to judge the fluctuation of heat input state. The two work together to achieve accurate identification of working conditions. Based on the identified working conditions and material welding adaptation requirements, the control unit calculates the target pressure value in conjunction with the actual pressure signal fed back by the pressure sensor 5. If there is a deviation between the actual pressure and the target pressure, a corresponding pressure adjustment command is generated.

[0040] When the execution unit receives the pressurization command from the control unit, the external oil supply device delivers hydraulic oil into the oil chamber 12 through the oil inlet 14, and at the same time draws hydraulic oil from the oil outlet 15. The hydraulic oil pushes the piston 13 to move the adjusting sleeve 2 toward the workpiece, thereby driving the stirring head 3 to press down and increase the pressure. When the pressure reduction command is received from the control unit, the external oil supply device delivers hydraulic oil to the oil chamber 12 through the oil outlet 15, and at the same time draws hydraulic oil from the oil inlet 14. The hydraulic oil pushes the piston 13 to move the adjusting sleeve 2 away from the workpiece, thereby driving the stirring head 3 to move upward, thereby reducing the pressure.

[0041] After the pressure regulation action is executed, the control unit collects the signal from the pressure sensor 5 again to verify whether the actual pressure has reached the target pressure preset range. If it has not reached the target pressure preset range, the above instruction generation and execution process is repeated to perform dynamic compensation adjustment.

[0042] Then, the control unit continuously receives real-time signals from the acquisition unit and dynamically corrects the pressure adjustment command to ensure that the pressure adjustment matches the changes in working conditions in real time, thus avoiding welding defects caused by adjustment lag.

[0043] In summary, a closed-loop control link is formed by the acquisition unit, control unit, and execution unit. The system uses torque sensor 4 to sense the torque signal reflecting the degree of material plasticity in real time, temperature sensor 6 to sense the temperature signal reflecting the thermal input state in real time, and pressure sensor 5 to provide actual pressure feedback. After the control unit performs linkage analysis and working condition identification on the torque and temperature signals, it dynamically generates commands to drive the execution unit to adjust the hydraulic oil flow direction and flow rate in the oil chamber 12, thereby accurately controlling the pressure of the stirring head 3. The control accuracy is ensured by the adjusted pressure verification mechanism. This system effectively overcomes the limitations of relying on preset curves or single parameters, and realizes adaptive pressure adjustment for special working conditions such as welding of dissimilar materials, transition of the welding steady-state stage, and hard spots, which significantly improves the stability of the welding process and the consistency of joint quality. Example

[0044] refer to Figures 1 to 6 An automatic pressure control method for friction stir welding includes the following steps: S1: Real-time signal acquisition During the welding process, the torque signal of the stirring head 3 is collected in real time by the torque sensor 4, the temperature signal of the welding zone is collected in real time by the temperature sensor 6, and the actual pressure signal acting on the workpiece is collected in real time by the pressure sensor 5.

[0045] S2: Linkage Analysis and Decision Making The acquired real-time torque and temperature signals are transmitted to the control unit, which then makes a comprehensive judgment based on the following logic rules: If the torque is higher than the set reference range and the temperature is lower than the set reference range, it is determined that the material is not sufficiently plasticized, and an instruction to increase the pressure is generated. If the torque is lower than the set reference range and the temperature is higher than the set reference range, it is determined that the material is too soft, and a command to reduce the pressure is generated. If both torque and temperature are within the steady-state reference range, a command is generated to maintain or fine-tune the pressure to keep the system stable.

[0046] S3: Adaptive Adjustment The control unit identifies the current welding stage or operating condition based on the temporal variation characteristics of torque and temperature signals, and performs precise pressure regulation. When the torque is detected to rise rapidly from the initial value to the peak value, and the temperature starts to rise from room temperature but has not yet reached the steady state range, it is determined that the welding stage has begun. In this stage, the control unit will issue a command to drive the adjusting sleeve 2 to press down rapidly through the external oil supply device of the actuator to implement rapid pressurization, so as to assist the initial plasticization of the material and prevent incomplete welding. When the torque is detected to decrease from its peak and stabilize within the set range, and the temperature is detected to rise and stabilize within the plasticizing temperature range, the steady-state welding stage is determined to be entered. In this stage, the control unit will instruct the execution unit to slowly adjust the pressure or keep it stable based on the small fluctuations in torque and temperature, in order to optimize weld formation and prevent collapse. When a sudden and drastic change in the torque signal is detected, such as a sharp increase, while the temperature signal does not change significantly in sync, it is determined that a special working condition such as encountering a hard point has been encountered. At this time, the control unit immediately triggers a fast response strategy, instructing the execution unit to quickly and slightly reduce the pressure within milliseconds to protect the stirring head 3 from abnormal load impact. After the torque signal recovers, the pressure is automatically adjusted to an appropriate value.

[0047] S4: Pressure Closed-Loop Execution and Feedback The control unit sends the pressure adjustment command generated in steps S2 and S3 to the execution unit. The execution unit controls the hydraulic oil to enter and exit the oil chamber 12, drives the piston 13 and the adjusting sleeve 2 to move, thereby changing the pressure of the stirring head 3 on the workpiece. Subsequently, the control unit reads the latest actual pressure value fed back by the pressure sensor 5 and determines whether it falls within the target pressure preset range determined according to the current working conditions.

[0048] S5: Pressure Verification and Compensation If the actual pressure value is determined to be outside the target preset range in step S4, the control unit will generate a compensation adjustment command based on the deviation calculation and send it to the execution unit for fine-tuning. After fine-tuning, return to step S4 for verification, forming an inner loop of "execution-verification-compensation" until the actual pressure value stabilizes within the target preset range.

[0049] During this process, pressure sensor 5 continuously feeds back the actual pressure signal to the control unit, forming a complete closed-loop control to ensure that the actual pressure value is accurately tracked and stabilized within the target pressure preset range. In summary, by using the control unit to make comprehensive judgments based on the coupling relationship between torque and temperature signals, and identifying special working conditions such as the initial welding stage, steady-state stage, or hard spots, and triggering differentiated pressure adjustment strategies for different working conditions, and through the pressure verification and compensation process after adjustment, the actual pressure is ensured to be tracked and maintained within the target value range in real time and accurately. This method deeply integrates the dynamic changes of the dual parameters of torque and temperature into the control logic, and strengthens the verification and correction of the final execution effect. It achieves precise matching between welding pressure and real-time material status, effectively preventing defects such as incomplete penetration, weld collapse, and abnormal wear of the stirring head 3, and greatly enhancing process adaptability and reliability.

[0050] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic pressure control device for friction stir welding, characterized in that, include: The cylinder block has a sealed oil chamber inside; The pressure regulating mechanism includes an adjusting sleeve slidably connected to the cylinder body and a piston fixedly connected to the outside of the adjusting sleeve and sealingly sliding in the oil chamber. The pressure regulating mechanism is used to adjust the pressure applied to the workpiece by the stirring head mounted thereon by hydraulically driving the adjusting sleeve to move along its axial direction. A rotary transmission mechanism includes a transmission shaft rotatably connected inside the adjusting sleeve via a radial bearing, the transmission shaft being used to transmit the rotational power of an external drive device to the stirring head; An axial force bearing mechanism includes a support member disposed on the outer periphery of the stirring head and a plane bearing installed between the support member and the adjusting sleeve. The axial force bearing mechanism is used to withstand the axial reaction force generated by welding and maintain the rotational stability of the stirring head during the axial movement of the adjusting sleeve and the rotation of the stirring head.

2. The automatic pressure control device for friction stir welding according to claim 1, characterized in that, The oil chamber is provided with an oil inlet and an oil outlet. Hydraulic oil flows into or out of the oil chamber through the oil inlet and the oil outlet to drive the piston and the adjusting sleeve to move axially in both directions.

3. An automatic pressure control system for friction stir welding, characterized in that, Includes the automatic pressure control device for friction stir welding as described in any one of claims 1-2, and: The acquisition unit includes a torque sensor, a pressure sensor, and a temperature sensor, used to acquire torque signals, actual pressure signals, and temperature signals in real time during the welding process; The control unit is used to receive and analyze torque signals, temperature signals and actual pressure signals, identify working conditions based on the linkage logic of torque and temperature and generate pressure regulation commands. The execution unit includes an external oil supply device for receiving pressure regulation commands and driving the regulating sleeve to move to change the pressure of the stirring head by adjusting the flow direction and flow rate of hydraulic oil in the oil chamber. The acquisition unit, control unit, and execution unit form a closed-loop control link to achieve real-time adaptive adjustment of welding pressure.

4. The automatic pressure control system for friction stir welding according to claim 3, characterized in that, The torque sensor is installed inside the adjusting sleeve and is used to connect the drive shaft and the external drive device to collect torque signals that reflect the degree of material plasticity. The pressure sensor is disposed between the adjusting sleeve and the plane bearing, and is used to detect the actual pressure signal applied to the workpiece by the stirring head; The temperature sensor is mounted on the outside of the cylinder with its detection end facing the stirring head via a bracket, and is used to collect temperature signals that reflect the welding heat input status in a non-contact manner. Both the oil inlet and the oil outlet are connected to the external oil supply device to achieve bidirectional flow control of hydraulic oil within the oil chamber.

5. An automatic pressure control method for friction stir welding, applied to the automatic pressure control system for friction stir welding as described in any one of claims 3-4, characterized in that, Includes the following steps: Real-time signal acquisition: The acquisition unit acquires torque signals, temperature signals, and actual pressure signals during the welding process in real time. Linkage analysis and decision-making: The torque signal and temperature signal are transmitted to the control unit, which performs linkage analysis on the two according to preset logic rules and generates a preliminary pressure adjustment command; Pressure closed-loop execution: The execution unit executes the initial pressure regulation command, and drives the regulating sleeve to move by adjusting the hydraulic oil in the oil chamber to change the pressure of the stirring head; Pressure verification and compensation: The control unit determines whether the latest actual pressure signal fed back by the pressure sensor falls within the target pressure preset range that matches the current welding conditions. If the pressure does not fall within the target range, a compensation adjustment command is generated and sent to the execution unit for pressure fine-tuning until the actual pressure signal stabilizes within the target pressure preset range.

6. The automatic pressure control method for friction stir welding according to claim 5, characterized in that, In the linkage analysis and decision-making process, the preset logical rules include: If the torque signal is higher than the set reference range and the temperature signal is lower than the set reference range, a command to increase the pressure is generated. If the torque signal is below the set reference range and the temperature signal is above the set reference range, a command to reduce the pressure is generated. If both the torque and temperature signals are within the steady-state reference range, a command to maintain or fine-tune the pressure is generated.

7. The automatic pressure control method for friction stir welding according to claim 5, characterized in that, In the linkage analysis and decision-making process, the control unit identifies the current welding stage or working condition based on the temporal variation characteristics of the torque signal and temperature signal, and executes a differentiated pressure regulation strategy based on the identification results. The identification and regulation strategies include: When the torque signal is detected to rise rapidly from its initial value to its peak value and the temperature signal is detected to rise from room temperature but not to a steady state, it is determined to be the welding start-up stage, and a rapid pressurization command is generated. When the torque and temperature signals are both detected to be stable within the set range, it is determined to be in the steady-state welding stage, and a command is generated to maintain the pressure or to slowly adjust it based on minor fluctuations. When a sudden and drastic change in the torque signal is detected while the temperature signal does not change significantly in sync, it is determined that a special working condition of encountering a hard point is encountered, and a rapid decompression command is generated.

8. The automatic pressure control method for friction stir welding according to claim 5, characterized in that, In the pressure closed-loop execution step, by controlling the hydraulic oil to enter and exit the oil chamber through the oil inlet and outlet, the piston and adjusting sleeve are driven to move axially, thereby changing the pressure of the stirring head on the workpiece, and the actual pressure signal is returned to the control unit through the continuous feedback of the pressure sensor.

9. The automatic pressure control method for friction stir welding according to claim 5, characterized in that, The pressure calibration and compensation steps specifically include: After each pressure closed-loop execution step is completed, the control unit immediately reads the latest actual pressure signal collected by the pressure sensor; Compare the latest actual pressure signal with the target pressure range preset for the current welding stage or working condition; If the latest actual pressure signal does not fall within the target pressure range, a compensation adjustment command is generated based on the magnitude and direction of the deviation, and the process returns to the pressure closed-loop execution step to perform fine-tuning. Repeat the above comparison and compensation process until the actual pressure signal stabilizes within the target pressure range.

10. The automatic pressure control method for friction stir welding according to claim 5, characterized in that, The pressure verification and compensation steps form an internal loop of execution, verification, and compensation, constituting a complete closed-loop control that ensures the actual pressure value is accurately tracked and stabilized within the target pressure preset range.

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