CN117773310B - Aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system - Google Patents
Aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system Download PDFInfo
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Abstract
The invention provides a space curve friction stir welding track tracking control system for an aluminum alloy ribbed wallboard, and belongs to the technical field of friction stir welding. The system comprises a laser vision sensor and a bracket, wherein the laser vision sensor is used for fixing the laser vision sensor on a numerical control machine; an actual weld position determining module is mounted on the laser vision sensor, and a weld correction control algorithm is mounted on the numerical control machine tool. The invention solves the problems of complex structure, incapability of directly tracking welding lines and poor stability of the conventional friction stir welding track tracking control system, and has the advantages of higher reliability and relatively simple system structure.
Description
Technical Field
The invention relates to the technical field of friction stir welding, in particular to a tracking control system for a space curve friction stir welding track of an aluminum alloy ribbed wallboard.
Background
Friction stir welding (Friction STIR WELDING, FSW) is a solid phase welding method proposed by the Institute for welding (THE WELDING Institute, TWI) in 1991, and is widely used in structures such as curved panels of foreign aircraft, warehouse floors, rocket fuel tanks, train bodies, and the like, because of its low stress, high strength, green and pollution-free properties. In the friction stir welding process, the distance of the axis of the stirring pin shifting from the center of the welding line can obviously influence the comprehensive performance of the joint. Therefore, aerospace industry standards dictate that the offset of the stirring head should be less than 0.1 times the plate thickness. In actual production, the linear welding seam generally adopts a method of welding spot/welding spot collection for pre-tool setting and offline programming of a preset track for the curved welding seam to reduce the deviation of the welding track. However, in the actual welding process, when the welding line track deviates from a preset path due to local deformation caused by uneven heating of the thin-wall workpiece or local buckling of the thin plate caused by unstable clamping, the stirring head cannot realize adaptive adjustment, and the quality of the joint may be adversely affected. Therefore, the welding seam position is tracked online in the welding process, the relative position of the axis of the stirring head is adjusted in real time, and the welding seam position tracking device has important engineering application value for manufacturing the thin-wall ribbed wallboard structure with high quality and high performance.
The patent publication No. CN111496370A provides an automatic sensing and controlling method for friction stir welding track suitable for angle joint. Firstly, the data measurement module calculates welding seam data in real time, the data processing module calculates stirring head adjusting data according to the measured data, and finally, the mechanical control module executes an adjusting instruction of the stirring head, so that the process of welding the angle joint does not need manual adjustment, and the position of the stirring head can be automatically adjusted to the straight right-angle welding seam or the arc right-angle welding seam to finish welding. In the scheme of the patent, the addition of the combined laser receiver ensures that the reflected laser beam is received by the range finder. The combined laser consists of a laser infrared range finder and six laser receivers. When the laser device works, the 6 laser receivers need to work simultaneously to prevent signal omission, so that the signal acquisition amount and the overall power consumption of the device are greatly increased.
The patent with publication number CN114905137A discloses a device based on a friction stir welding process of a side wall plate of a motor train unit, which comprises a FSW assembly welding tool of the side wall plate of the motor train unit and a welding assembly; the FSW assembly welding tool for the side wall plates of the motor train unit is provided with a plurality of supporting beams which are in contact with the side wall plates of the motor train unit and support the side wall plates of the motor train unit, and the upper surfaces of the supporting beams are processed into arc-surface structures matched with the radians of the corresponding positions of the side wall plates of the motor train unit; the welding assembly is provided with a weld tracker, a stirring head and a pressing wheel; the weld tracker is arranged on the side surface of the stirring head and moves synchronously with the stirring head. The above patent solutions adopt a solution in which a weld tracker is arranged on the side of the stirring head and moves in parallel with the stirring head in synchronization. The weld tracker moves along the track of the weld side tracking line during welding. The scheme needs to track the weld line and has higher parallelism and is aimed at the weld line with continuous variable curvature, so that the adaptability of the scheme is lower.
The patent with publication number CN116038089A proposes an adsorption friction stir welding method based on a sheet aluminum alloy. The method is realized by a welding trolley and comprises a trolley body and a main machine part inside the trolley body. The vehicle body comprises an inner sucker group, an outer sucker group, an x-axis motor and a y-axis motor; the main machine part comprises an electric spindle frame, an electric spindle for friction stir welding, a stirring head, a z-axis motor and a transverse motor. The electric spindle is connected with a visual recognition camera and an infrared visual sensor for collecting welding line position signals and is used for tracking welding lines in real time during friction stir welding. The above patent solutions do not give details of embodiments of visual recognition cameras and infrared vision sensors for real-time tracking of welds during friction stir welding.
The patent with publication number CN115805358A proposes an information integration system based on fuzzy control, which comprises a friction welding system integration module, a welding seam deviation calculation and detection module and a friction welding seam tracking module. The friction welding system integration module is used for integrating a robot, a hydraulic spindle and a parameter detection and self-adaptive control subsystem in the friction welding system through the central control unit; the welding seam deviation calculation and detection module is used for extracting and calculating welding seam deviation information through the internal calibration of the sensor of the self-adaptive control subsystem and the calibration of the robot; the friction weld tracking module is used for realizing dynamic compensation of the robot and simultaneously realizing automatic tracking and automatic control of weld forming quality for debugging the weld of the self-adaptive control subsystem. The welding seam deviation calculation and detection module comprises a coordinate system creation module, a coordinate solving module, a calibration module and a welding seam deviation calculation module. The system performs measurement, solving, calibration and deviation calculation based on the three-dimensional coordinates corresponding to the laser sensor, and aims at one-dimensional flat welding and two-dimensional curved product welding, and the system is complex in structure and high in stable operation risk.
In summary, the conventional friction stir welding track tracking control system has the problems of complex structure, incapability of directly tracking welding lines and poor stability, and cannot realize accurate welding of space curves of aluminum alloy thin-wall ribbed wallboard.
Disclosure of Invention
The invention solves the technical problems that: the existing friction stir welding track tracking control system has the defects of complex structure, incapability of directly tracking welding lines and poor stability.
In order to solve the problems, the technical scheme of the invention is as follows:
the laser vision sensor is used for fixing the laser vision sensor on a bracket on the numerical control machine tool;
An actual weld position determining module carried on the laser vision sensor,
The welding seam deviation correcting control module, the simulation module and the proportional-derivative control module are carried on the numerical control machine tool;
The actual welding seam position obtained by the actual welding seam position determining module is obtained through the welding seam deviation correcting control module, the actual welding seam position is brought into the simulation module, the deviation distance between the actual welding seam position and the theoretical welding seam position is obtained, whether deviation correction is needed or not is judged, the deviation correcting needed deviation direction and the deviation distance are calculated through the proportional-differential control module under the condition that deviation correction is needed, and the numerical control machine tool is controlled to adjust the actual welding seam position according to the deviation correcting needed deviation direction and the deviation distance.
As one aspect of the present invention, a stent includes: the support plate is fixedly connected with a main shaft mounting frame of the numerical control machine tool, the support plate is vertically and rotatably connected with a rotating shaft through a nut, a rotating block is slidably connected on the rotating shaft, a rotating groove is fixedly connected on the outer side of the rotating block, the rotating groove is rotatably connected with a laser vision sensor through an adapter plate, and the laser vision sensor is electrically connected with the numerical control machine tool through a sensor cable.
Description: the bracket can enable the laser beam position to be as close to the front edge of the shaft shoulder of the stirring head as possible, so that the front distance of the laser vision sensor is reduced to the minimum, and the deviation caused by the change of the slope of the welding line can be reduced as much as possible when the welding line structure is suddenly changed.
As an aspect of the present invention, the laser vision sensor is further provided with a guide head, a control box, and a control hand box.
Description: the arrangement of the guide head, the control box and the control hand box is beneficial to realizing the stable identification of the welding seam by the laser vision sensor and teaching the central position of the welding seam; the guiding head has a laser detection function and guides the advancing direction of the stirring head; the control box receives the photoelectric signals measured by the guide head for calculation and analysis and outputs voltage analog signals to the machine tool; the control hand box is used for adjusting parameters such as laser power, laser beam grating length and the like.
As one aspect of the invention, the actual weld position determining module performs weld tracking based on the laser vision sensor, converts the deviation amount of the weld position into a voltage analog signal and transmits the voltage analog signal to the numerical control machine tool.
Description: the voltage analog quantity signal obtained by the laser vision sensor can be further converted into a digital signal which can be recognized by a numerical control system in the numerical control machine tool through the internal self-contained module, and the practical scheme is convenient to realize.
As one aspect of the invention, the voltage analog signal has a voltage range of [ -10V, 10V ], an output value of 0V when the weld joint has no deviation, and an output signal of-10V when the deviation reaches the maximum in the negative direction, and 10V on the contrary.
Description: from the above, the invention directly makes the stirring head perpendicular to the surface of the welding line in the plane through off-line programming, so the data acquisition amount, the total calculation amount and the response speed are all higher than those of the prior art.
As one aspect of the present invention, the obtaining the actual weld position obtained by the actual weld position determining module is: the numerical control machine receives the voltage analog quantity signal output by the laser vision sensor, and converts the voltage analog quantity signal into a digital signal through digital-to-analog conversion.
Description: the voltage analog quantity signal obtained by the laser vision sensor can be further converted into a digital signal which can be recognized by a numerical control system in the numerical control machine tool through the internal self-contained module, and the practical scheme is convenient to realize.
As one aspect of the present invention, the offset distance between the actual weld position and the theoretical weld position is obtained, and whether deviation correction is required is determined as follows: converting the digital signal into an offset distance through an offset distance conversion equation, comparing the offset distance with a critical value, and judging that deviation correction is required if the offset distance is greater than or equal to the critical value; wherein, the critical value is 0.1 times of the thickness of the aluminum alloy thin-wall ribbed wallboard.
Description: by setting the critical value, the offset distance between the actual welding seam position and the theoretical welding seam position is ensured not to influence the final welding effect.
As one aspect of the present invention, the offset distance is obtained by an offset distance conversion equation, which is:
y=0.0025×u-0.8928, where Y is the offset distance and U is the voltage of the digital signal.
Description: offset distance conversion can more closely translate digital signals into offset distances.
As one aspect of the invention, the theoretical weld locations are: and before welding, setting a welding line track of the laser vision sensor by using image processing software.
Description: the welding seam is designed before welding, so that the welding seam can be used as a basis for judging the welding position in the welding process, and the welding effect is ensured.
As one aspect of the invention, the actual weld position determination module has a duty cycle of 20 ms.
Description: the working period of the actual welding seam position determining module can meet the welding seam tracking control requirements under different welding seam offset degrees, so that the automatic adjustment of the deviation correcting speed of the machine tool at different deviation distances is realized, and overshoot is reduced as much as possible.
As one aspect of the invention, the duty cycle of the weld error correction control algorithm is 20 ms.
Description: the working period of the welding seam deviation correction control algorithm can meet the welding seam tracking control requirements under different welding seam deviation degrees, so that the automatic adjustment of the deviation correction speed of the machine tool at different deviation distances is realized, and the overshoot is reduced as much as possible.
The beneficial effects of the invention are as follows:
(1) Aiming at the problems that the prior art is complex in structure, can not directly track welding lines and is poor in system operation stability, the welding line measurement positioning is realized through single line laser, the curve welding deviation is reduced by enabling a laser beam grating to be close to the shaft shoulder of a stirring head through an autonomously designed bracket, the quantitative relation between the deviation amount and the voltage analog amount is constructed, and finally the stirring friction butt joint of the aluminum alloy ribbed wallboard or the automatic tracking control of the lap joint welding line is realized;
(2) The invention adopts the laser vision sensor, and adopts the decomposition type adjustment method to construct the weld tracking control system by designing the laser vision sensor, so that the reliability of the established weld tracking control system is higher and the system structure is relatively simple;
(3) The invention can be popularized and applied in the automatic production and manufacture of the aluminum alloy and magnesium alloy plate ribbed wallboard structure in the fields of aerospace, ships, automobiles and the like, and realizes the high-quality and high-efficiency welding of the light high-strength alloy.
Drawings
FIG. 1 is a block diagram of a stent in an embodiment of the present invention;
FIG. 2 is a diagram of a rack-mounted state in an embodiment of the present invention;
FIG. 3 is a graph of the relationship between the actual welding track and the actual weld joint position when the prepositive distance is large;
FIG. 4 is a graph of actual weld trajectory versus actual weld position for smaller lead distances;
FIG. 5 is a weld tracking teaching and test image;
FIG. 6 is a graph showing the linear relationship between the offset and the digital signal according to the embodiment of the present invention;
FIG. 7 is a logic diagram of weld trajectory correction in an embodiment of the present invention;
FIG. 8 is a graph of curved weld travel trajectories at different weld speeds;
the device comprises a 1-laser vision sensor, a 2-sensor cable, a 3-adapter plate, a 4-rotating groove, a 5-rotating block, a 6-rotating shaft, a 7-nut, an 8-support plate, a 9-spindle mounting frame, a 10-spindle, an 11-cutter handle, a 12-stirring head, a 13-laser beam grating and a 14-welding seam.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, the "plurality" generally includes at least two.
The friction stir welding is used as a low-stress, high-strength, green and pollution-free solid-phase welding method, and in the actual welding process, when a welding line track deviates from a preset path due to local deformation caused by uneven heating of a thin-wall workpiece or local buckling of a thin plate caused by clamping instability, the stirring head cannot realize adaptive adjustment, and the quality of a joint can be adversely affected.
In order to solve the above problems, this embodiment describes a space curve friction stir welding track tracking control system for an aluminum alloy ribbed wallboard, including:
the laser vision sensor 1 is used for fixing the laser vision sensor 1 on a bracket of the numerical control machine tool;
an actual weld position determining module mounted on the laser vision sensor 1,
The welding seam deviation correcting control module, the simulation module and the proportional-derivative control module are carried on the numerical control machine tool;
Because the weld joint structure is complex, when the weld joint structure is suddenly changed in the actual welding travelling process, the sensor generates deviation due to the existence of a front distance (the horizontal distance from the laser beam grating to the stirring head), as shown in fig. 3 and 4; the theoretical welding path of the butt-joint plate is A-B, but the actual welding path is A-C-D due to factors such as local deformation and warping caused by larger internal stress of the plate and insufficient clamping, larger machining tolerance of the plate and the like; when the horizontal distance from the laser beam grating to the stirring head is larger and the stirring head moves to a position E, the deviation between the position of the welding line measured by the laser beam grating and the theoretical path reaches a critical value, a deviation correction control algorithm program outputs a signal instruction to control the welding head to deviate towards the negative direction of the Y axis, the deviation measured subsequently is continuously increased, the welding head continuously deviates towards the negative direction of the Y axis, and the welding line from E1 to F1 is actually formed finally; at the moment, the position offset of the butt welding seam between the actual welding track and the actual plate is larger, and meanwhile, the E1 section to the D section are not welded, as shown in fig. 3; when the horizontal distance from the laser beam grating to the stirring head is smaller, and the offset measured by the laser beam grating reaches the critical value, the E2 point basically reaches the C point, the actual welding track is basically coincident with the actual welding seam position, the offset is within an acceptable range, and the joint can be effectively connected;
In order to reduce the front distance as much as possible, the laser vision sensor 1 and the bracket are designed in this embodiment, as shown in fig. 1, the bracket includes: the support plate 8 is fixedly connected with a main shaft mounting frame 9 of the numerical control machine tool, the support plate 8 is vertically and rotatably connected with a rotating shaft 6 through a nut 7, a rotating block 5 is slidably connected on the rotating shaft 6, a rotating groove 4 is fixedly connected to the outer side of the rotating block 5, the rotating groove 4 is rotatably connected with the laser vision sensor 1 through an adapter plate 3, and the laser vision sensor 1 is electrically connected with the numerical control machine tool through a sensor cable 2;
It can be understood that the bottom of the spindle mounting rack 9 is longitudinally fixed with a spindle 10, the bottom of the spindle 10 is fixed with a tool shank 11, the bottom of the tool shank 11 is fixed with a stirring head 12, as shown in fig. 2, the bottom of the stirring head 12 is provided with a laser beam grating 13, and the laser beam grating 13 is intersected with a welding line 14;
Specifically, the laser vision sensor 1 is mounted on the adapter plate 3 through a screw, and the adapter plate 3 is mounted on the rotary groove 4 through a screw; the lower part of the rotary groove 4 is connected and fastened with the rotary block through a screw, and a milling groove at the upper part of the rotary groove 4 can rotate in a vertical plane by taking the lower screw as a center to adjust the angle of the laser vision sensor 1; the rotating block 5 is sleeved on the rotating shaft 6 and can move up and down freely along the rotating shaft 6 to adjust the height of the laser vision sensor, and the laser vision sensor 1 is fastened by a screw after reaching a proper height; the rotating shaft 6 is arranged on the support plate 8 through a nut 7, and the support plate 8 is connected with the end face of the main shaft mounting frame 9 through a screw to root, so that an acting point is provided for the whole set of laser ranging system; the bracket can enable the laser beam position to be as close to the front edge of the shaft shoulder of the stirring head as possible (as shown in figure 2), so that the front distance of the laser vision sensor is reduced to the minimum, and the deviation caused by the change of the slope of the welding line can be reduced as much as possible when the welding line structure is suddenly changed;
It can be understood that in this embodiment, the laser vision sensor 1 is further provided with a guide head, a control box and a control hand box; the guiding head has a laser detection function and guides the advancing direction of the stirring head; the control box receives the photoelectric signals measured by the guide head for calculation and analysis and outputs voltage analog signals to the machine tool; the control hand box is used for adjusting parameters such as laser power, laser beam grating length and the like;
From the above, teaching of the initial position of the weld joint can be realized through the guide head, the control box and the control hand box; before welding, performing system and weld joint form setting on the sensor through image processing software (the image processing software adopted in the embodiment is Unigraphics NX) so as to realize stable identification of the sensor on the weld joint and teach the center position of the weld joint, as shown in a figure 5; in the display window, two horizontal gray solid lines represent laser beam gratings, a dashed frame body between the two line segments is the center of a welding line, a black cross mark inside the dashed frame body is the center position of the actual welding line, after teaching, the center of the welding line coincides with the center position of the actual welding line, the purpose of calibration is achieved, and the offset is 0mm at the moment.
As shown in fig. 7, the actual weld position obtained by the actual weld position determining module is obtained through the weld deviation correcting control module, the actual weld position is brought into the simulation module, the deviation distance between the actual weld position and the theoretical weld position is obtained, whether deviation correction is needed or not is judged, the deviation correcting needed deviation direction and the deviation distance are calculated through the proportional-differential control module under the condition that deviation correction is needed, and the numerical control machine is controlled to adjust the actual weld position according to the deviation correcting needed deviation direction and the deviation distance;
Optionally, in this embodiment, the simulation module is: compiling a weld deviation correction control algorithm simulation module into a TMC format file which can be identified by TwinCat software through a Build model function in Simulink software, and importing the TMC format file into TwinCat software to realize;
It can be understood that the actual weld position determining module performs weld tracking based on the laser vision sensor 1, converts the deviation amount of the weld position into a voltage analog signal and transmits the voltage analog signal to the numerical control machine tool; wherein, the voltage range of the voltage analog quantity signal is [ -10V, 10V ], when the welding line has no deviation, the output value is 0V, when the deviation reaches the maximum in the negative direction, the output signal is-10V, and on the contrary, is 10V;
it will be appreciated that, as shown in fig. 2, the left side of the stirring head is in a negative direction and the right side is in a positive direction along the advancing direction of the stirring head; secondly, the embodiment only considers Y-direction deviation and does not consider X-direction deviation;
Specifically, before welding, a theoretical welding track is obtained through UG software under-line programming, then a control hand box of a laser vision sensor is used for adjusting a laser beam grating to align with a welding starting point, and the starting point is defined as a welding seam origin; starting a welding program and a laser tracking deviation correction control program, starting welding and correcting the deviation according to the actual welding seam position; the total width of the laser beam grating is 50mm, the positive direction measuring range is 25mm, and the corresponding voltage measuring range is 10V; when the positive offset is detected to be 0.02mm, the output voltage value is 0.008V;
Wherein UG (Unigraphics NX) is a product engineering solution available from SIEMENS PLM Software company, which provides a digital modeling and verification means for the product design and processing process of users; unigraphics NX provides a practically verified solution for the requirements of virtual product design and process design of users and meeting various industrial requirements;
It can be understood that the actual weld position obtained by the actual weld position determining module is: the numerical control machine receives the voltage analog quantity signal output by the laser vision sensor 1, and converts the voltage analog quantity signal into a digital signal through digital-to-analog conversion;
It can be understood that the offset distance between the actual weld position and the theoretical weld position is obtained, and whether deviation correction is needed is judged as follows: converting the digital signal into an offset distance through an offset distance conversion equation, comparing the offset distance with a critical value, and judging that deviation correction is required if the offset distance is greater than or equal to the critical value; wherein, the critical value is 0.1 times of the thickness of the aluminum alloy thin-wall ribbed wallboard;
From the above, when the offset is smaller than the critical value, the Y direction is not corrected, and the stirring head continues to weld; when the offset is greater than or equal to a critical value, correcting the Y direction, calculating a digital signal generating an offset direction and an offset distance through a proportion-derivative (PD) control module carried by the numerical control machine, correcting the motion of each axis of the machine according to the digital signal, welding the stirring head forwards along the X direction, continuously acquiring the offset distance by the laser vision sensor 1, and judging whether to continue correcting the offset; when the weld offset is greater than the grating range of the laser, the proportional-derivative (PD) control module can also calculate the subsequent output offset direction and offset speed through the acquired data;
Wherein, the proportional-derivative (PD) control module belongs to a self-carried program of a numerical control machine tool, belongs to the prior art, and is not repeated here;
Correspondingly, in the welding seam deviation calculation and detection module in the patent CN 115805358A, a sensor coordinate system and a robot tool coordinate system are constructed, a space vector EF and a peak coordinate point C in the advancing direction of a stirring head of the robot and a foot coordinate point D of the vector EF are measured and calculated, and the length of a CD is used as the deviation; the method needs to measure the space coordinates of C, D, E, F four points;
In the embodiment, the stirring head is vertical to the surface of the welding line in the plane directly through off-line programming, so that the data acquisition amount, the total calculation amount and the response speed of the embodiment are all higher than those of the prior art;
It can be appreciated that the theoretical weld locations are: before welding, performing weld track setting on the laser vision sensor 1 by using image processing software (Unigraphics NX);
it can be appreciated that the offset distance is obtained by an offset distance conversion equation, which is:
y=0.0025×u-0.8928, where Y is the offset distance and U is the voltage of the digital signal; the relationship between the digital signal and the offset distance is shown in fig. 6; the offset distance refers to the distance between the actual position of the welding seam and the theoretical position of the welding seam set by off-line programming of the workpiece;
It will be appreciated that the above formula may also convert the digital signal into a distance value, namely: u=400×y+357.12; optionally, in this embodiment, in order to adapt to the weld seam tracking control requirements under different weld seam offset degrees, the automatic adjustment and deviation correction speeds of different deviation distances of the machine tool are realized, and overshoot is reduced as much as possible, and the working period of the actual weld seam position determining module is 20 ms; the working period of the welding seam deviation correction control algorithm is 20 ms;
In specific application, due to the structural characteristics of a curve welding line, the welding is performed in a welding line tracking and guiding mode, so that a grating of a laser vision sensor loses the welding line at an inflection point, and guiding welding is invalid; therefore, the welding seam of the structure is welded in a deviation rectifying manner, namely, a numerical control machine (NC) welding program is written according to a tool path track obtained through digital-analog offline processing of the welding seam, a workpiece to be welded is deliberately clamped and deviated from a correct position, deviation of workpiece clamping is rectified and welded on an existing motion track, as shown in fig. 8, black is realized as a motion track of a stirring head when the welding seam tracking control is not adopted, other curves are motion tracks of the welding seam tracking control under different welding speeds, the deviation of the two tracks is about 4.5 mm to the maximum, meanwhile, the superposition of the tracks of different welding speeds under the deviation rectifying condition can be seen, and the adaptability of the welding seam tracking system to the different welding speeds is good.
The offset in the process of weld joint tracking control under different welding speeds is integrally distributed in the intervals of [ -0.1 mm and 0.1 mm ], and the tracking precision is 0.00021 mm at the highest when the welding speed is 200 mm/min; the final joint has higher surface quality, is even and smooth, and can locally observe the ripple generated by the action of the shaft shoulder of the stirring head during the deviation correcting motion.
Claims (6)
1. The utility model provides an aluminum alloy area muscle wallboard space curve friction stir welding orbit tracking control system which characterized in that includes:
the laser vision sensor (1) is used for fixing the laser vision sensor (1) on a bracket of the numerical control machine tool;
an actual weld position determining module carried on the laser vision sensor (1),
The welding seam deviation rectifying control module, the simulation module and the proportional-derivative control module are carried on the numerical control machine tool;
acquiring an actual welding seam position obtained by the actual welding seam position determining module through the welding seam deviation correcting control module, bringing the actual welding seam position into the simulation module, acquiring the deviation distance between the actual welding seam position and the theoretical welding seam position, judging whether deviation correction is needed, calculating the deviation direction and the deviation distance needed by deviation correction through the proportional-differential control module under the condition that the deviation correction is needed, and controlling the numerical control machine tool to adjust the actual welding seam position according to the deviation direction and the deviation distance needed by deviation correction;
the actual weld joint position determining module performs weld joint tracking based on the laser vision sensor (1), converts deviation of the weld joint position into a voltage analog signal and transmits the voltage analog signal to the numerical control machine tool;
the actual welding seam position obtained by the actual welding seam position obtaining module is as follows: the numerical control machine receives the voltage analog quantity signal output by the laser vision sensor (1), and converts the voltage analog quantity signal into a digital signal through digital-to-analog conversion;
The offset distance between the actual welding seam position and the theoretical welding seam position is obtained, and whether deviation correction is needed or not is judged as follows: converting the digital signal into an offset distance through an offset distance conversion equation, comparing the offset distance with a critical value, and judging that deviation correction is required if the offset distance is greater than or equal to the critical value; wherein, the critical value is 0.1 times of the thickness of the aluminum alloy thin-wall ribbed wallboard;
The offset distance is obtained through an offset distance conversion equation, and the offset distance conversion equation is as follows:
Y=0.0025×U-0.8928，
In the above formula, Y is an offset distance in mm, and U is the voltage of the digital signal in V.
2. The aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system of claim 1, wherein the bracket comprises: the support plate (8) is fixedly connected with a main shaft mounting frame (9) of the numerical control machine tool, the support plate (8) is vertically connected with a rotating shaft (6) through a nut (7), a rotating block (5) is connected to the rotating shaft (6) in a sliding mode, a rotating groove (4) is fixedly connected to the outer side of the rotating block (5), the rotating groove (4) is rotationally connected with the laser vision sensor (1) through an adapter plate (3), and the laser vision sensor (1) is electrically connected with the numerical control machine tool through a sensor cable (2).
3. The aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system according to claim 1, wherein the laser vision sensor (1) is further provided with a guide head, a control box and a control hand box.
4. The aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system according to claim 1, wherein the theoretical welding seam position is obtained by setting a welding seam track of a laser vision sensor (1) through image processing software.
5. The aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system of claim 1, wherein the actual weld position determination module has a duty cycle of 20 ms.
6. The aluminum alloy ribbed wallboard space curve friction stir welding track tracking control system of claim 1, wherein the weld correction control algorithm has a duty cycle of 20 ms.
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