Adjustable pressure workpiece clamping device for friction stir welding and control system

Abstract

The application discloses a workpiece pressing equipment with adjustable pressure for friction stir welding and a control system, relates to the technical field of friction stir welding, and comprises a welding platform, a welding mechanism and a control system, wherein the control system comprises a pressure acquisition unit, a balance analysis unit, a pressure balance unit and a control unit; the workpiece positioning mechanism and the side pressing mechanism are matched with each other to fix the workpiece to be welded, then the film pressure sensor arranged in the pressure sensing cavity is used to acquire pressure data one, the air pressure sensor arranged in the expansion capsule is used to acquire pressure data two, the pressure fluctuation curve is established according to a time axis, the pressure fluctuation coefficients are respectively calculated to judge the pressure abnormal state, the pressure balance signal is obtained, the pressure imbalance point is determined according to the pressure balance signal source, the pressure balance object is determined according to the position coordinates of the pressure imbalance point, and the parameter is adjusted to ensure the fixing stability of the workpiece in the friction stir welding process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of friction stir welding, in particular to a workpiece pressing equipment with adjustable pressure for friction stir welding and a control system. BACKGROUND

[0002] As an advanced solid-phase connection technology, friction stir welding has significant advantages in the welding of light metals such as aluminum alloy and magnesium alloy. It has low heat input, excellent microstructure and performance, wide material applicability, environmental protection and efficiency advantages, and excellent joint mechanical properties. Therefore, it is widely used in battery box welding processing. However, due to its principle of rotating and advancing while welding, it often appears to be stirred when encountering uneven surfaces, especially for large boxes.

[0003] Therefore, the prior art has the following problems:

[0004] I. Welding forming defects: when the welded joint passes through the protruding part of the surface, the flash is generated, which affects the welding quality and appearance, and the incomplete penetration easily leads to uneven workpiece surface, which causes the gap between the upper and lower lap joints, resulting in tunnel holes during welding, affecting the welding strength and sealing performance.

[0005] II. High scrap rate: when the welding flatness exceeds a certain range, the stirring head will directly cause the entire battery box to be scrapped when the protruding surface is scraped.

[0006] In view of the above technical defects, the present application provides a solution. SUMMARY

[0007] The purpose of the present application is to fix the workpiece to be welded by the cooperation of the workpiece positioning mechanism and the side pressing mechanism, and then obtain pressure data one by the thin film pressure sensor arranged inside the pressure sensing cavity and pressure data two by the gas pressure sensor arranged inside the expansion capsule, and establish a pressure fluctuation curve according to the time axis, calculate the pressure fluctuation coefficient respectively to judge the pressure abnormal state, obtain the pressure balance signal, determine the pressure imbalance point according to the source of the pressure balance signal, and select the pressure balance object according to the position coordinates of the pressure imbalance point, and adjust the parameters to ensure the stability of the workpiece during the friction stir welding process.

[0008] In order to achieve the above purpose, the present application adopts the following technical scheme: a workpiece pressing equipment with adjustable pressure for friction stir welding, comprising a welding platform and a welding mechanism, the outer surface of the welding platform is movably installed with a gantry support, the welding mechanism is fixedly arranged on the bottom surface of the gantry support, the top surface of the welding platform is provided with a weld joint positioning mark, the top surface of the welding platform is provided with two groups of corresponding workpiece positioning mechanisms, the top surface of the welding platform is provided with an embedded groove, and the inner wall of the embedded groove is fixedly provided with a side pressing mechanism.

[0009] The side pressing mechanism comprises a driving assembly and a pressing assembly, a plurality of groups of the driving assembly is fixedly arranged on the inner wall of the embedding groove, the top surface of the plurality of groups of the driving assembly is connected with a pushing plate, a plurality of the pressing assemblies are uniformly distributed on the top surface of the pushing plate, the pressing assembly comprises a side pressing plate and a pressing block, the inside of the pushing plate is provided with a lifting groove, the inner wall of the lifting groove is movably connected with a lifting sleeve, the inner wall of the lifting sleeve and the inner wall of the lifting groove are jointly connected with a top pressing spring, the side pressing plate is fixedly arranged on the top surface of the lifting sleeve, the pressing block is fixedly arranged on one side surface of the side pressing plate, the bottom end surface of the pressing block is in contact with the top end surface of the workpiece, the inside of the pressing block is fixedly arranged with a pneumatic pressure regulating assembly, the top end surface of the pressing block is fixedly arranged with a magnet filling block, the inside of the welding platform is fixedly arranged with a plurality of parallel arranged electromagnets.

[0010] Further, the welding mechanism comprises a welding head and a vertical pressing assembly, the gantry support is connected to the outer side surface of the welding platform through an electric guide rail, the bottom end surface of the gantry support is fixedly arranged with a welding power source, the welding head is fixedly arranged on the output end outer side surface of the welding power source, and the vertical pressing assembly is fixedly arranged on the bottom end surface of the gantry support.

[0011] Further, the vertical pressing assembly comprises a vertical support and a hydraulic shaft, the vertical support is fixedly arranged on the bottom end surface of the gantry support, the hydraulic shaft is fixedly arranged on the bottom end surface of the vertical support, the output end outer side surface of the hydraulic shaft is connected with a vertical pressing block, the bottom end surface of the vertical pressing block is in close contact with the surface of the workpiece, and the inside of the vertical pressing block is fixedly arranged with a pressure sensing assembly.

[0012] Further, the pressure sensing assembly comprises a pressure sensing block and a thin film pressure sensor, the bottom end surface of the vertical pressing block is provided with a pressure sensing cavity, the inner wall of the pressure sensing cavity is fixedly arranged with an elastic filling block, the pressure sensing block is fixedly arranged on the bottom end surface of the elastic filling block, the bottom end surface of the pressure sensing block is flush with the bottom end surface of the vertical pressing block, and a plurality of the thin film pressure sensors are uniformly distributed on the top end surface of the elastic filling block.

[0013] Further, the workpiece positioning mechanism comprises a hydraulic pump and a hydraulic push rod, the hydraulic pump is fixedly arranged on the top end surface of the welding platform, the hydraulic push rod is connected to the output end outer side surface of the hydraulic pump, and the terminal surface of the hydraulic push rod is connected with a positioning push plate.

[0014] Further, the driving assembly comprises a linear rail and a servo motor, the linear rail is fixedly arranged on the inner wall of the embedding groove, the servo motor is fixedly arranged on the inner wall of the linear rail, the output end outer side surface of the servo motor is fixedly arranged with a ball screw, the outer side surface of the ball screw is sleeved with a sliding table, and the pushing plate is fixedly arranged on the bottom end surface of the sliding table.

[0015] Further, the pneumatic pressure regulating assembly comprises an expansion capsule and a suction pump, a regulating cavity is arranged on the bottom end surface of the pressure block, the expansion capsule is fixedly arranged on the inner wall of the regulating cavity, a pressure bottom plate is fixedly arranged on the bottom end surface of the expansion capsule, the suction pump is fixedly arranged on the top end surface of the pressure block, a communication pipeline is connected between the output end of the suction pump and the expansion capsule, an air pressure sensor is fixedly arranged in the expansion capsule, an extension plug plate is connected to the outer surface of the pressure bottom plate, an extension groove corresponding to the extension plug plate is arranged in the pressure block, a limiting protrusion is fixedly arranged on the inner wall of the extension groove, and the top end surface of the limiting protrusion is in movable contact with the top end surface of the extension plug plate.

[0016] The application also provides a control system of the adjustable workpiece pressing equipment for friction stir welding, comprising a pressure acquisition unit, a balance analysis unit, a pressure balance unit and a control unit.

[0017] The pressure acquisition unit is used to acquire pressure data one through the thin film pressure sensor arranged in the pressure sensing cavity and pressure data two through the air pressure sensor arranged in the expansion capsule, and to establish a pressure fluctuation curve according to a time axis, and to integrate the pressure fluctuation graph and send it to the balance analysis unit.

[0018] The balance analysis unit comprises a modeling positioning module and a balance analysis module, the modeling positioning module is used to acquire image data of the workpiece to be processed through a camera, to acquire edge feature points in the image data through feature extraction, to establish a space coordinate system based on the size data of the welding platform and the gantry, and to mark the edge feature points one by one in the space coordinate system, and to connect the edge feature points with a smooth curve to obtain an edge feature curve.

[0019] The balance analysis module is used to acquire and process the pressure fluctuation graph, to extract pressure fluctuation curve one and pressure fluctuation curve two according to the pressure fluctuation graph, to calculate the pressure fluctuation coefficients respectively, to determine the pressure abnormal state according to the preset pressure fluctuation threshold, and to generate a pressure balance signal and send it to the pressure balance unit.

[0020] The pressure balance unit is used to acquire and process the pressure balance signal, to determine the pressure imbalance point according to the source of the pressure balance signal, to acquire the position coordinates of the pressure imbalance point in the space coordinate system, to determine the pressure balance object according to the position coordinates of the pressure imbalance point, and to generate a corresponding control instruction and send it to the control unit.

[0021] The control unit is used to control the corresponding pressure balance object to adjust parameters according to the control instruction, so as to ensure the fixing stability of the workpiece in the friction stir welding process.

[0022] Further, the specific process of generating the pressure balance signal is as follows:

[0023] S1, acquire a pressure fluctuation graph, the pressure fluctuation graph comprising a two-dimensional coordinate system with a time axis as an abscissa and a pressure unit as an ordinate, and a pressure fluctuation curve one and a pressure fluctuation curve two;

[0024] S2, sequentially select the pressure fluctuation curve one and the pressure fluctuation curve two, and define a pressure stable section on the pressure fluctuation curve one and the pressure fluctuation curve two respectively according to a preset positioning stable period, acquire pressure nodes Fi in the pressure stable section according to the time axis, and correspondingly acquire position coordinates at the pressure nodes;

[0025] S3, calculate a pressure fluctuation slope Ki in the pressure stable section according to the following formula: wherein Fi1(xi1, yi1) and Fi2(xi2, yi2) are two adjacent pressure nodes, i=1, 2, 3, …, n, and n is the total number of pressure nodes, and the pressure fluctuation slope Ki in the pressure stable section is taken as a preset pressure fluctuation threshold value;

[0026] S4, select pressure detection nodes on the pressure fluctuation curve one and the pressure fluctuation curve two according to a preset calculation frequency, and calculate a pressure fluctuation coefficient Kp one by one according to the following formula: wherein a is a preset proportional coefficient, N is the total number of pressure detection nodes, Fj1(xj1, yj1) and Fj2(xj2, yj2) are two adjacent pressure detection nodes, and the pressure fluctuation coefficient is used to reflect the pressure fluctuation situation of the edge line and the weld of the workpiece;

[0027] S5, if the pressure fluctuation coefficient is greater than the pressure fluctuation threshold value, a pressure balance signal is generated.

[0028] As described above, due to the adoption of the above technical scheme, the present application has the following beneficial effects:

[0029] The workpiece pressing equipment with adjustable pressure for friction stir welding and the control system, through the cooperation of the workpiece positioning mechanism and the side pressing mechanism, the workpiece to be welded is fixed, and then the pressure data one is acquired by the thin film pressure sensor arranged in the pressure sensing cavity and the pressure data two is acquired by the air pressure sensor arranged in the expansion capsule, and the pressure fluctuation curve is established according to the time axis, the pressure fluctuation coefficient is calculated respectively to judge the pressure abnormal state, the pressure balance signal is obtained, the pressure imbalance point is determined according to the source of the pressure balance signal, the pressure balance object is selected according to the position coordinates of the pressure imbalance point, and the fixing stability of the workpiece in the friction stir welding process is ensured after parameter adjustment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The overall external structure schematic diagram of the present application is shown;

[0031] Figure 2 Another angle overall external structure schematic diagram of the present application is shown;

[0032] Figure 3 A side pressing mechanism internal structure schematic diagram of the present application is shown;

[0033] Figure 4 Another angle side pressing mechanism internal structure schematic diagram of the present application is shown;

[0034] Figure 5 A pressing block internal structure schematic diagram of the present application is shown;

[0035] Figure 6 A vertical pressing block internal structure schematic diagram of the present application is shown;

[0036] Figure 7 A control system structure schematic diagram of the present application is shown;

[0037] Legend: 1, welding platform; 2, gantry support; 3, weld positioning mark; 4, embedded groove; 5, pushing plate; 6, lifting groove; 7, lifting sleeve; 8, top pressing spring; 9, pressing block; 10, welding power source; 11, welding head; 12, vertical support; 13, hydraulic shaft; 14, vertical pressing block; 15, pressure sensing cavity; 16, elastic filling block; 17, pressure sensing block; 18, thin film pressure sensor; 19, hydraulic pump; 20, hydraulic push rod; 21, positioning push plate; 22, straight rail; 23, servo motor; 24, ball screw; 25, sliding table; 26, adjusting cavity; 27, expansion capsule; 28, suction pump; 29, communication pipeline; 30, air pressure sensor; 31, extension plugboard; 32, extension groove; 33, limit protrusion; 34, magnet filling block; 35, electromagnet; 36, side pressing plate; 37, pressing bottom plate. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0039] Embodiment 1:

[0040] As Figures 1-6As shown, an adjustable pressure workpiece pressing device for friction stir welding includes a welding platform 1 and a welding mechanism, the outer surface of the welding platform 1 is movably provided with a gantry support 2, the welding mechanism is fixedly arranged on the bottom end surface of the gantry support 2, the top end surface of the welding platform 1 is provided with a weld joint positioning mark 3, the top end surface of the welding platform 1 is provided with two groups of corresponding workpiece positioning mechanisms, the top end surface of the welding platform 1 is provided with an embedded groove 4, and the inner wall of the embedded groove 4 is fixedly provided with a side pressing mechanism.

[0041] The side pressing mechanism includes a driving assembly and a pressing assembly, a plurality of driving assemblies are fixedly arranged on the inner wall of the embedded groove 4, the top end surface of the plurality of driving assemblies is commonly connected with a push plate 5, a plurality of pressing assemblies are uniformly distributed on the top end surface of the push plate 5, the pressing assembly includes a side pressing plate 36 and a pressure block 9, the inside of the push plate 5 is provided with a lifting groove 6, the inner wall of the lifting groove 6 is movably connected with a lifting sleeve 7, the inner wall of the lifting sleeve 7 and the inner wall of the lifting groove 6 are commonly connected with a top pressing spring 8, the side pressing plate 36 is fixedly arranged on the top end surface of the lifting sleeve 7, the pressure block 9 is fixedly arranged on one side surface of the side pressing plate 36, the bottom end surface of the pressure block 9 is in contact with the top end surface of the workpiece, the inside of the pressure block 9 is fixedly provided with a pneumatic pressure regulating assembly, the top end surface of the pressure block 9 is fixedly provided with a magnet filling block 34, and the inside of the welding platform 1 is fixedly provided with a plurality of parallel arranged electromagnets 35.

[0042] The welding mechanism includes a welding head 11 and a vertical pressing assembly, the gantry support 2 is connected to the outer surface of the welding platform 1 through an electric guide rail, the bottom end surface of the gantry support 2 is fixedly provided with a welding power source 10, the welding head 11 is fixedly arranged on the output end outer surface of the welding power source 10, and the vertical pressing assembly is fixedly arranged on the bottom end surface of the gantry support 2.

[0043] The vertical pressing assembly includes a vertical support 12 and a hydraulic shaft 13, the vertical support 12 is fixedly arranged on the bottom end surface of the gantry support 2, the hydraulic shaft 13 is fixedly arranged on the bottom end surface of the vertical support 12, the output end outer surface of the hydraulic shaft 13 is connected with a vertical pressing block 14, the bottom end surface of the vertical pressing block 14 is in close contact with the surface of the workpiece, and the inside of the vertical pressing block 14 is fixedly provided with a pressure sensing assembly.

[0044] The pressure sensing assembly includes a pressure sensing block 17 and a thin film pressure sensor 18, the bottom end surface of the vertical pressing block 14 is provided with a pressure sensing cavity 15, the inner wall of the pressure sensing cavity 15 is fixedly provided with an elastic filling block 16, the pressure sensing block 17 is fixedly arranged on the bottom end surface of the elastic filling block 16, the bottom end surface of the pressure sensing block 17 is flush with the bottom end surface of the vertical pressing block 14, and a plurality of thin film pressure sensors 18 are uniformly distributed on the top end surface of the elastic filling block 16.

[0045] The workpiece positioning mechanism comprises a hydraulic pump 19 and a hydraulic push rod 20, the hydraulic pump 19 is fixedly arranged on the top surface of the welding platform 1, the hydraulic push rod 20 is connected to the outer side surface of the output end of the hydraulic pump 19, and the end surface of the hydraulic push rod 20 is connected with a positioning push plate 21.

[0046] The driving assembly comprises a linear rail 22 and a servo motor 23, the linear rail 22 is fixedly arranged on the inner wall of the embedding groove 4, the servo motor 23 is fixedly arranged on the inner wall of the linear rail 22, the output end outer side surface of the servo motor 23 is fixedly provided with a ball screw 24, the outer side surface of the ball screw 24 is sleeved with a sliding table 25, and the advancing plate 5 is fixedly arranged on the bottom end surface of the sliding table 25.

[0047] The pneumatic pressure regulating assembly comprises an expansion capsule 27 and a suction pump 28, the bottom end surface of the pressure block 9 is provided with an adjusting cavity 26, the expansion capsule 27 is fixedly arranged on the inner wall of the adjusting cavity 26, the bottom end surface of the expansion capsule 27 is fixedly provided with a pressure bottom plate 37, the suction pump 28 is fixedly arranged on the top end surface of the pressure block 9, the output end of the suction pump 28 and the expansion capsule 27 are jointly connected with a communication pipeline 29, the inside of the expansion capsule 27 is fixedly provided with an air pressure sensor 30, the outer side surface of the pressure bottom plate 37 is connected with an extension plug plate 31, the inside of the pressure block 9 is provided with an extension groove 32 corresponding to the extension plug plate 31, the inner wall of the extension groove 32 is fixedly provided with a limiting protrusion 33, and the top end surface of the limiting protrusion 33 is in movable contact with the top end surface of the extension plug plate 31.

[0048] In use, the workpieces to be processed are placed on the welding platform 1 in sequence, the edges to be welded are placed along the welding seam positioning mark 3, the workpieces to be processed are placed in a stack at the welding seam positioning mark 3, the coincident parts are coincident with each other, the hydraulic pump 19 is controlled by the control system to drive the hydraulic push rod 20, and then the positioning push plate 21 is driven to move close to the edges of the workpieces, the workpieces are clamped from the horizontal direction by the two positioning push plates 21 that move relative to each other, and the reference positions of the workpieces on two sides are fixed;

[0049] The servo motor 23 is controlled by the control system to drive the ball screw 24 to rotate, the sliding table 25 is driven to move along the linear rail 22, the advancing plate 5 is driven to move close to the other two edges of the workpiece, until the lateral pressing plate is in contact with the edges of the workpiece, the electromagnet 35 is electrified at this time, the magnetism of the corresponding surface of the electromagnet 35 and the magnet filling block 34 is opposite, the pressure block 9 is driven to move downward along the lifting groove 6 under the action of magnetic attraction, the pressure block 9 is in contact with the top end surface of the workpiece, the workpiece is pressed from the vertical direction, and the pressure is balanced by the plurality of pressure blocks 9 that are uniformly distributed, so that the pressure points are uniformly distributed, and the pressing effect is guaranteed;

[0050] The movable gantry 2 is driven to move horizontally along the welding platform 1 by the electric guide rail, the welding head 11 is driven to move along the weld positioning mark 3 by the welding power source 10, and the workpiece is welded, and in the welding process, the vertical pressing block 14 is driven to move downward by the hydraulic shaft 13, the coincident part of the workpiece is vertically pressed, and the welding is assisted;

[0051] In the welding process, the pressure data one is obtained by the thin film pressure sensor 18, the pressure data one is used for feedback pressure balance condition of the welding position of the workpiece, and the pressure data two in the inflatable capsule 27 is obtained by the air pressure sensor 30, the pressure data two is used for feedback pressure balance condition in the state of pressing the side of the workpiece, when the pressure data one is unbalanced, the output parameter of the hydraulic shaft 13 is adjusted, the downward pressure of the vertical pressing block 14 is increased, and the accurate welding site is ensured;

[0052] When the pressure data two is unbalanced, the output parameter of the suction pump 28 is controlled, the inflatable capsule 27 is inflated by the suction pump 28, the inflatable capsule 27 is inflated to press the pressurizing bottom plate 37, the contact between the pressurizing bottom plate 37 and the workpiece is more close, the pressure on the side of the workpiece is increased, and the accurate positioning is ensured.

[0053] Embodiment 2:

[0054] As shown in Figure 7 ,

[0055] The application also provides a control system of the workpiece pressing equipment with adjustable pressure for friction stir welding, which comprises a pressure acquisition unit, a balance analysis unit, a pressure balance unit and a control unit.

[0056] The pressure acquisition unit is used for acquiring the pressure data one by the thin film pressure sensor 18 arranged in the pressure sensing cavity 15 and acquiring the pressure data two by the air pressure sensor 30 arranged in the inflatable capsule 27, and a pressure fluctuation curve is established according to a time axis, and a pressure fluctuation graph is integrated and sent to the balance analysis unit.

[0057] The balance analysis unit comprises a modeling positioning module and a balance analysis module, the modeling positioning module is used for acquiring image data of a workpiece to be processed by a camera, acquiring edge feature points in the image data through feature extraction, establishing a space coordinate system based on size data of the welding platform 1 and the movable gantry, and marking the edge feature points one by one in the space coordinate system, and connecting the edge feature points by a smooth curve to obtain an edge feature curve.

[0058] The balance analysis module is used for acquiring and processing the pressure fluctuation graph, extracting a pressure fluctuation curve one and a pressure fluctuation curve two according to the pressure fluctuation graph, respectively calculating pressure fluctuation coefficients, judging a pressure abnormal state according to a preset pressure fluctuation threshold, and generating a pressure balance signal and sending the pressure balance signal to the pressure balance unit.

[0059] The specific process of generating the pressure balance signal is as follows:

[0060] S1, acquire a pressure fluctuation graph, the pressure fluctuation graph comprising a two-dimensional coordinate system with a time axis as the abscissa and a pressure unit as the ordinate, and a pressure fluctuation curve one and a pressure fluctuation curve two;

[0061] S2, sequentially select the pressure fluctuation curve one and the pressure fluctuation curve two, and define a pressure stable section on the pressure fluctuation curve one and the pressure fluctuation curve two respectively with a preset positioning stable period, acquire a plurality of pressure nodes Fi in the pressure stable section according to the time axis, and correspondingly acquire the position coordinates of the pressure nodes;

[0062] S3, calculate the pressure fluctuation slope Ki in the pressure stable section according to the following formula: wherein Fi1(xi1, yi1) and Fi2(xi2, yi2) are two adjacent pressure nodes, i = 1, 2, 3, …, n, n is the total number of pressure nodes, and the pressure fluctuation slope Ki in the pressure stable section is taken as a preset pressure fluctuation threshold;

[0063] S4, select pressure detection nodes on the pressure fluctuation curve one and the pressure fluctuation curve two according to a preset calculation frequency, and calculate the pressure fluctuation coefficient Kp one by one according to the following formula: wherein α is a preset proportion coefficient, N is the total number of pressure detection nodes, Fj1(xj1, yj1) and Fj2(xj2, yj2) are two adjacent pressure detection nodes, and the pressure fluctuation coefficient is used to reflect the pressure fluctuation at the edge line and the weld of the workpiece;

[0064] S5, if the pressure fluctuation coefficient is greater than the pressure fluctuation threshold, a pressure balance signal is generated.

[0065] The pressure balance unit is used for acquiring and processing the pressure balance signal, determining the pressure imbalance point according to the source of the pressure balance signal, acquiring the position coordinates of the pressure imbalance point in the spatial coordinate system, selecting a pressure balance object according to the position coordinates of the pressure imbalance point, and generating a corresponding control instruction according to the pressure balance object and sending the control instruction to the control unit;

[0066] The control unit is used for controlling the corresponding pressure balance object to adjust parameters according to the control instruction, so as to ensure the fixing stability of the workpiece in the friction stir welding process.

[0067] The present application obtains pressure data one through the thin film pressure sensor 18 arranged in the pressure sensing cavity 15 and obtains pressure data two through the air pressure sensor 30 arranged in the inflation balloon 27, and establishes a pressure fluctuation curve according to a time axis, extracts pressure fluctuation curve one and pressure fluctuation curve two according to the pressure fluctuation graph, respectively calculates the pressure fluctuation coefficient, judges the pressure abnormal state according to the preset pressure fluctuation threshold, generates the pressure balance signal, determines the pressure imbalance point according to the source of the pressure balance signal, and obtains the position coordinates of the pressure imbalance point in the spatial coordinate system, selects the pressure balance object according to the position coordinates of the pressure imbalance point, controls the corresponding pressure balance object to perform parameter adjustment, and ensures the fixing stability of the workpiece in the friction stir welding process.

[0068] The size of the threshold is set for easy comparison. The size of the threshold depends on the amount of sample data and the base number set by the person skilled in the art for each group of sample data; as long as it does not affect the proportional relationship between the parameters and the quantized values.

[0069] The above formulas are dimensionless values calculated, the formula is obtained by collecting a large amount of data to simulate the most real situation, and the preset parameters in the formula are set by the person skilled in the art according to the actual situation;

[0070] In the two embodiments provided in the present application, it should be understood that the disclosed device and system can be implemented in other ways; for example, the device embodiments described above are only schematic, for example, the division of the modules is only a logical function division, and actual implementation can have another division manner, for example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed; in addition, the coupling or direct coupling or communication connection between the displayed or discussed ones can be indirect coupling or communication connection through some interfaces, devices or modules, which can be electrical, mechanical or other forms;

[0071] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A workpiece hold-down apparatus for friction stir welding having an adjustable pressure, characterized by, Including welding platform (1) and welding mechanism, the outer surface of the welding platform (1) is movably installed with gantry bracket (2), the welding mechanism is fixed on the bottom end surface of gantry bracket (2), the top end surface of the welding platform (1) is provided with weld positioning mark (3), the top end surface of the welding platform (1) is provided with two groups of corresponding workpiece positioning mechanism, the top end surface of the welding platform (1) is provided with embedded groove (4), the inner wall of the embedded groove (4) is fixed with side pressing mechanism; The welding mechanism includes welding head (11) and vertical pressing assembly, the gantry bracket (2) is connected to the outer surface of the welding platform (1) through the electric guide rail, the bottom end surface of the gantry bracket (2) is fixed with welding power source (10), the welding head (11) is fixed on the output end outer surface of the welding power source (10), and the vertical pressing assembly is fixed on the bottom end surface of the gantry bracket (2); The vertical pressing assembly includes vertical support (12) and hydraulic shaft (13), the vertical support (12) is fixed on the bottom end surface of the gantry bracket (2), the hydraulic shaft (13) is fixed on the bottom end surface of the vertical support (12), the output end outer surface of the hydraulic shaft (13) is connected with vertical pressing block (14), the bottom end surface of the vertical pressing block (14) is in close contact with the surface of the workpiece, and the vertical pressing block (14) is internally provided with pressure sensing assembly; The pressure sensing assembly includes pressure sensing block (17) and film pressure sensor (18), the bottom end surface of the vertical pressing block (14) is provided with pressure sensing cavity (15), the inner wall of the pressure sensing cavity (15) is fixed with elastic filling block (16), the pressure sensing block (17) is fixed on the bottom end surface of the elastic filling block (16), the bottom end surface of the pressure sensing block (17) is flush with the bottom end surface of the vertical pressing block (14), and a plurality of film pressure sensors (18) are uniformly distributed on the top end surface of the elastic filling block (16); The side pressing mechanism comprises driving assemblies and pressing assemblies, the top surfaces of the driving assemblies are connected with a pushing plate (5), the pressing assemblies are evenly distributed on the top surface of the pushing plate (5), the pressing assembly comprises a side pressing plate (36) and a pressing block (9), the inside of the pushing plate (5) is provided with a lifting groove (6), the inner wall of the lifting groove (6) is movably connected with a lifting sleeve (7), the inner wall of the lifting sleeve (7) and the inner wall of the lifting groove (6) are movably connected with a top pressing spring (8), the side pressing plate (36) is fixedly arranged on the top surface of the lifting sleeve (7), the pressing block (9) is fixedly arranged on one side surface of the side pressing plate (36), the bottom end surface of the pressing block (9) is in contact with the top end surface of the workpiece, the inside of the pressing block (9) is fixedly arranged with a pneumatic pressure regulating assembly, the top end surface of the pressing block (9) is fixedly arranged with a magnet filling block (34), the inside of the welding platform (1) is fixedly arranged with a plurality of parallel arranged electromagnets (35); The pneumatic pressure regulating assembly comprises an expansion capsule (27) and a suction pump (28), the bottom end surface of the pressing block (9) is provided with an adjusting cavity (26), the expansion capsule (27) is fixedly arranged on the inner wall of the adjusting cavity (26), the bottom end surface of the expansion capsule (27) is fixedly arranged with a pressing bottom plate (37), the suction pump (28) is fixedly arranged on the top end surface of the pressing block (9), the output end of the suction pump (28) and the expansion capsule (27) are movably connected with a communication pipeline (29), the inside of the expansion capsule (27) is fixedly arranged with a gas pressure sensor (30), the outside surface of the pressing bottom plate (37) is connected with an extension plug plate (31), the inside of the pressing block (9) is provided with an extension groove (32) corresponding to the extension plug plate (31), the inner wall of the extension groove (32) is fixedly arranged with a limiting protrusion (33), the top end surface of the limiting protrusion (33) is movably in contact with the top end surface of the extension plug plate (31).

2. The adjustable pressure workpiece hold-down apparatus for friction stir welding of claim 1, wherein, The workpiece positioning mechanism comprises a hydraulic pump (19) and a hydraulic push rod (20), the hydraulic pump (19) is fixedly arranged on the top end surface of the welding platform (1), the hydraulic push rod (20) is connected to the output end outside surface of the hydraulic pump (19), the terminal surface of the hydraulic push rod (20) is connected with a positioning push plate (21).

3. The adjustable pressure workpiece hold-down apparatus of claim 1, wherein: The driving assembly comprises a linear rail (22) and a servo motor (23), the linear rail (22) is fixedly arranged on the inner wall of the embedding groove (4), the servo motor (23) is fixedly arranged on the inner wall of the linear rail (22), the output end outside surface of the servo motor (23) is fixedly arranged with a ball screw (24), the outside surface of the ball screw (24) is sleeved with a sliding table (25), the pushing plate (5) is fixedly arranged on the bottom end surface of the sliding table (25).

4. A control system for a variable pressure workpiece hold-down apparatus for friction stir welding, applied to the variable pressure workpiece hold-down apparatus for friction stir welding according to claim 1, characterized by, The pressure acquisition unit, the balance analysis unit, the pressure balancing unit and the control unit are included. The pressure acquisition unit is configured to acquire pressure data one by a thin film pressure sensor (18) arranged inside a pressure sensing cavity (15) and acquire pressure data two by a gas pressure sensor (30) arranged inside the inflatable balloon (27), and establish a pressure fluctuation curve according to a time axis, and integrate the pressure fluctuation curve to obtain a pressure fluctuation graph and send the pressure fluctuation graph to the balance analysis unit; The balance analysis unit includes a modeling positioning module and a balance analysis module. The modeling positioning module is configured to acquire image data of the workpiece to be processed by a camera, extract edge feature points in the image data, establish a spatial coordinate system based on size data of the welding platform (1) and the gantry, and mark the edge feature points one by one in the spatial coordinate system, and connect the edge feature points with a smooth curve to obtain an edge feature curve. The balance analysis module is configured to acquire and process the pressure fluctuation graph, extract pressure fluctuation curve one and pressure fluctuation curve two from the pressure fluctuation graph, calculate the pressure fluctuation coefficients, determine the pressure abnormal state according to the preset pressure fluctuation threshold, and generate a pressure balance signal and send the pressure balance signal to the pressure balance unit. The pressure balance unit is configured to acquire and process the pressure balance signal, determine the pressure imbalance point according to the source of the pressure balance signal, acquire the position coordinates of the pressure imbalance point in the spatial coordinate system, select the pressure balance object according to the position coordinates of the pressure imbalance point, and generate a corresponding control instruction according to the pressure balance object and send the control instruction to the control unit. The control unit is configured to control the corresponding pressure balance object to adjust parameters according to the control instruction, and ensure the stability of the workpiece during the friction stir welding process.

5. The control system of the adjustable workpiece clamping apparatus for friction stir welding according to claim 4, wherein The specific process of generating the pressure balance signal is as follows: S1, acquire the pressure fluctuation graph, the pressure fluctuation graph includes a two-dimensional coordinate system with time axis as horizontal coordinate and pressure unit as vertical coordinate, and pressure fluctuation curve one and pressure fluctuation curve two; S2, select pressure fluctuation curve one and pressure fluctuation curve two in turn, and define pressure stable sections on pressure fluctuation curve one and pressure fluctuation curve two respectively according to the preset positioning stable period, acquire pressure nodes Fi in the pressure stable sections according to the time axis, and correspondingly acquire the position coordinates of the pressure nodes; S3, calculate the pressure fluctuation slope Ki in the pressure stable section according to the following formula: Wherein Fi1(xi1, yi1) and Fi2(xi2, yi2) are two adjacent pressure nodes, i = 1, 2, 3, …, n, n is the total number of pressure nodes, and the pressure fluctuation slope Ki in the pressure stable section is taken as a preset pressure fluctuation threshold. S4、According to the preset calculation frequency, the pressure detection nodes are selected on the pressure fluctuation curve one and the pressure fluctuation curve two, and the pressure fluctuation coefficients Kp are calculated according to the following formula one by one: Wherein, α is a preset proportional coefficient, N is the total number of pressure detection nodes, Fj1(xj1, yj1) and Fj2(xj2, yj2) are two adjacent pressure detection nodes, and the pressure fluctuation coefficient is used to reflect the pressure fluctuation at the edge line and the weld of the workpiece. S5, if the pressure fluctuation coefficient is greater than the pressure fluctuation threshold, a pressure balance signal is generated.

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